Menu

6044712633046909955702945 MASTER THESIS In Order to Obtain the RESEARCH MASTER In Immunology Presented and defended by

0 Comment

6044712633046909955702945
MASTER THESIS
In Order to Obtain the
RESEARCH MASTER
In
Immunology
Presented and defended by:
Santia Khoury DiabOn Day 00 September, 2018
Title
Effect of Pitavastatin in carbon tetrachloride – induced liver fibrosis in mice
Supervisor
Dr. Eva HamadeDr. Aida HabibReviewers
Dr.
Dr.
Lebanese University-Faculty of sciences

Acknowledgment
Table of Contents TOC o “1-3” h z u Acknowledgment PAGEREF _Toc523299588 h 2Table of Contents PAGEREF _Toc523299589 h 3List of Abbreviations PAGEREF _Toc523299590 h 5List of Figures PAGEREF _Toc523299591 h 6List of Tables PAGEREF _Toc523299592 h 6Abstract PAGEREF _Toc523299593 h 7Résumé PAGEREF _Toc523299594 h 8Chapter I: Introduction PAGEREF _Toc523299595 h 91. Hepatic fibrosis PAGEREF _Toc523299596 h 92. Architecture of the normal liver PAGEREF _Toc523299597 h 102.1. Anatomy PAGEREF _Toc523299598 h 102.2. Function PAGEREF _Toc523299599 h 112.3. Cells within the liver PAGEREF _Toc523299600 h 112.4. The liver in health and disease PAGEREF _Toc523299601 h 143. Pathway of liver fibrosis PAGEREF _Toc523299602 h 143.1. Composition and remodeling of ECM PAGEREF _Toc523299603 h 153.2. Immune response PAGEREF _Toc523299604 h 153.3. Profibrotic mediators PAGEREF _Toc523299605 h 154. Regression of fibrosis PAGEREF _Toc523299606 h 154.1 Extracellular matrix degradation PAGEREF _Toc523299607 h 15HSCs apoptosis PAGEREF _Toc523299608 h 155. Effect of Statins on hepatic fibrosis PAGEREF _Toc523299609 h 16Aim of the Project PAGEREF _Toc523299610 h 18Chapter II: Materials and methods PAGEREF _Toc523299611 h 191. Animals PAGEREF _Toc523299612 h 192. Experimental Design PAGEREF _Toc523299613 h 192.1 Carbon tetrachloride- (CCL4-) induced liver injury PAGEREF _Toc523299614 h 192.2 Antifibrotic effect of Pitavastatin on liver fibrosis. PAGEREF _Toc523299615 h 192.3 Regression effect of Pitavastatin on liver fibrosis PAGEREF _Toc523299616 h 193. Pico Sirius Red staining. PAGEREF _Toc523299617 h 204. Immunohistochemistry staining of hepatic ?SMA. PAGEREF _Toc523299618 h 205. ALT and AST detection PAGEREF _Toc523299619 h 216. RNA Extraction PAGEREF _Toc523299620 h 217. Reverse transcription-PCR PAGEREF _Toc523299621 h 228. Real-Time PCR PAGEREF _Toc523299622 h 229. Statistical analysis PAGEREF _Toc523299623 h 23Chapter III: Results PAGEREF _Toc523299624 h 241. Experimental liver fibrosis model PAGEREF _Toc523299625 h 241.1 Serum ALT AST PAGEREF _Toc523299626 h 24Chapter IV: Discussion and Conclusion PAGEREF _Toc523299627 h 25Chapter V: Future perspectives PAGEREF _Toc523299628 h 26References PAGEREF _Toc523299629 h 27

We Will Write a Custom Essay Specifically
For You For Only $13.90/page!


order now

List of AbbreviationsList of Figures TOC h z c “Figure” Figure 1: Structure of the healthy liver 5. PAGEREF _Toc523254739 h 10Figure 2: Cellular modifications in the sinusoid during liver injury 19. PAGEREF _Toc523254740 h 14Figure 3: PAGEREF _Toc523254741 h 15Figure 4:  schematic summary of the signaling pathway by which statins decrease portal pressure and reduce hepatic fibrosis 30. PAGEREF _Toc523254742 h 17Figure 5: Schematic representation of the liver fibrosis model in male C57BL/6J mice. PAGEREF _Toc523254743 h 19
List of Tables TOC h z c “Table” Table 1: List of primer sequences used for RT-PCR analysis. PAGEREF _Toc523254702 h 21

Abstract
Résumé
Chapter I: IntroductionLiver disease is a major cause of morbidity and mortality worldwide, and the sequent loss of liver function is a critical clinical challenge. There are many different types of liver disease, which can be broadly grouped into three categories: chronic liver disease caused by metabolic dysfunction, acute liver failure that does not damage normal tissue structure, however is related to direct injury and rapid deterioration of hepatic function. Also, chronic liver failure that is associated with widespread tissue damage and scar-based remodeling, which can eventually lead to end-stage cirrhosis and hepatocellular carcinoma ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”7YU8AqlW”,”properties”:{“formattedCitation”:”1″,”plainCitation”:”1″,”noteIndex”:0},”citationItems”:{“id”:66,”uris”:”http://zotero.org/users/local/dX36zxw6/items/A29872Z6″,”uri”:”http://zotero.org/users/local/dX36zxw6/items/A29872Z6″,”itemData”:{“id”:66,”type”:”article-journal”,”title”:”Cell and Tissue Engineering for Liver Disease”,”container-title”:”Science translational medicine”,”page”:”245sr2″,”volume”:”6″,”issue”:”245″,”source”:”PubMed Central”,”abstract”:”Despite the tremendous hurdles presented by the complexity of the liver’s structure and function, advances in liver physiology, stem cell biology and reprogramming, and the engineering of tissues and devices are accelerating the development of cell-based therapies for treating liver disease and liver failure. This State of the Art Review discusses both the near and long-term prospects for such cell-based therapies and the unique challenges for clinical translation.”,”DOI”:”10.1126/scitranslmed.3005975″,”ISSN”:”1946-6234″,”note”:”PMID: 25031271
PMCID: PMC4374645″,”journalAbbreviation”:”Sci Transl Med”,”author”:{“family”:”Bhatia”,”given”:”Sangeeta N.”},{“family”:”Underhill”,”given”:”Gregory H.”},{“family”:”Zaret”,”given”:”Kenneth S.”},{“family”:”Fox”,”given”:”Ira J.”},”issued”:{“date-parts”:”2014″,7,16}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 1.

Hepatic damage can be induced by several factors including viral infection (hepatitis B and C), alcohol abuse, autoimmune hepatitis and chronic cholangiopathies. Also accelerated liver injury due to nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) is associated with obesity rates. This situation can cause chronic hepatic inflammation and deregulated wound healing process in the liver, which, if prolonged, can lead to fibrosis ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”nEZrFrAA”,”properties”:{“formattedCitation”:”2″,”plainCitation”:”2″,”noteIndex”:0},”citationItems”:{“id”:61,”uris”:”http://zotero.org/users/local/dX36zxw6/items/2ZDMS72K”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/2ZDMS72K”,”itemData”:{“id”:61,”type”:”article-journal”,”title”:”Management strategies for liver fibrosis”,”container-title”:”Annals of Hepatology”,”page”:”48-56″,”volume”:”16″,”issue”:”1″,”source”:”PubMed”,”abstract”:”Liver fibrosis resulting from chronic liver injury are major causes of morbidity and mortality worldwide. Among causes of hepatic fibrosis, viral infection is most common (hepatitis B and C). In addition, obesity rates worldwide have accelerated the risk of liver injury due to nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH). Also liver fibrosis is associated with the consumption of alcohol, or autoimmune hepatitis and chronic cholangiophaties. The response of hepatocytes to inflammation plays a decisive role in the physiopathology of hepatic fibrosis, which involves the recruitment of both pro- and anti-inflammatory cells such as monocytes and macrophages. As well as the production of other cytokines and chemokines, which increase the stimulus of hepatic stellate cells by activating proinflammatory cells. The aim of this review is to identify the therapeutic options available for the treatment of the liver fibrosis, enabling the prevention of progression when is detected in time.”,”DOI”:”10.5604/16652681.1226814″,”ISSN”:”1665-2681″,”note”:”PMID: 28051792″,”journalAbbreviation”:”Ann Hepatol”,”language”:”eng”,”author”:{“family”:”Altamirano-Barrera”,”given”:”Alejandra”},{“family”:”Barranco-Fragoso”,”given”:”Beatriz”},{“family”:”Méndez-Sánchez”,”given”:”Nahum”},”issued”:{“date-parts”:”2017″,2}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 2.

1. Hepatic fibrosisHepatic fibrosis is the main complication of chronic liver failure and characterized by the excessive accumulation of an altered extracellular matrix, that is extremely rich in type I and III collagens. Deposition of scar tissue results from a wound healing response that occurs to maintain liver integrity after several insults from various biochemical metabolites ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”PR8G59F5″,”properties”:{“formattedCitation”:”3″,”plainCitation”:”3″,”noteIndex”:0},”citationItems”:{“id”:78,”uris”:”http://zotero.org/users/local/dX36zxw6/items/6PR3LU25″,”uri”:”http://zotero.org/users/local/dX36zxw6/items/6PR3LU25″,”itemData”:{“id”:78,”type”:”article-journal”,”title”:”Cellular mechanisms of tissue fibrosis. 5. Novel insights into liver fibrosis”,”container-title”:”American Journal of Physiology. Cell Physiology”,”page”:”C789-799″,”volume”:”305″,”issue”:”8″,”source”:”PubMed”,”abstract”:”Liver fibrosis is the common scarring reaction associated with chronic liver injury that results from prolonged parenchymal cell injury and/or inflammation. The fibrogenic response is characterized by progressive accumulation of extracellular matrix components enriched in fibrillar collagens and a failure of matrix turnover. This process is driven by a heterogeneous population of hepatic myofibroblasts, which mainly derive from hepatic stellate cells and portal fibroblasts. Regression of fibrosis can be achieved by the successful control of chronic liver injury, owing to termination of the fibrogenic reaction following clearance of hepatic myofibroblasts and restoration of fibrolytic pathways. Understanding of the complex network underlying liver fibrogenesis has allowed the identification of a large number of antifibrotic targets, but no antifibrotic drug has as yet been approved. This review will highlight recent advances regarding the mechanisms that regulate liver fibrogenesis and fibrosis regression, with special focus on novel signaling pathways and the role of inflammatory cells. Translation of these findings to therapies will require continued efforts to develop multitarget therapeutic approaches that will improve the grim prognosis of liver cirrhosis.”,”DOI”:”10.1152/ajpcell.00230.2013″,”ISSN”:”1522-1563″,”note”:”PMID: 23903700″,”journalAbbreviation”:”Am. J. Physiol., Cell Physiol.”,”language”:”eng”,”author”:{“family”:”Mallat”,”given”:”Ariane”},{“family”:”Lotersztajn”,”given”:”Sophie”},”issued”:{“date-parts”:”2013″,10,15}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 3. However, the continuous unbalanced synthesis of matrix protein and degradation leads to an incomplete matrix remodeling and irreversible cirrhosis ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”PSctsZ2D”,”properties”:{“formattedCitation”:”4″,”plainCitation”:”4″,”noteIndex”:0},”citationItems”:{“id”:76,”uris”:”http://zotero.org/users/local/dX36zxw6/items/EINLTY6N”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/EINLTY6N”,”itemData”:{“id”:76,”type”:”article-journal”,”title”:”Remodeling and homeostasis of the extracellular matrix: implications for fibrotic diseases and cancer”,”container-title”:”Disease Models ; Mechanisms”,”page”:”165-178″,”volume”:”4″,”issue”:”2″,”source”:”PubMed Central”,”abstract”:”Dynamic remodeling of the extracellular matrix (ECM) is essential for development, wound healing and normal organ homeostasis. Life-threatening pathological conditions arise when ECM remodeling becomes excessive or uncontrolled. In this Perspective, we focus on how ECM remodeling contributes to fibrotic diseases and cancer, which both present challenging obstacles with respect to clinical treatment, to illustrate the importance and complexity of cell-ECM interactions in the pathogenesis of these conditions. Fibrotic diseases, which include pulmonary fibrosis, systemic sclerosis, liver cirrhosis and cardiovascular disease, account for over 45% of deaths in the developed world. ECM remodeling is also crucial for tumor malignancy and metastatic progression, which ultimately cause over 90% of deaths from cancer. Here, we discuss current methodologies and models for understanding and quantifying the impact of environmental cues provided by the ECM on disease progression, and how improving our understanding of ECM remodeling in these pathological conditions is crucial for uncovering novel therapeutic targets and treatment strategies. This can only be achieved through the use of appropriate in vitro and in vivo models to mimic disease, and with technologies that enable accurate monitoring, imaging and quantification of the ECM.”,”DOI”:”10.1242/dmm.004077″,”ISSN”:”1754-8403″,”note”:”PMID: 21324931
PMCID: PMC3046088″,”shortTitle”:”Remodeling and homeostasis of the extracellular matrix”,”journalAbbreviation”:”Dis Model Mech”,”author”:{“family”:”Cox”,”given”:”Thomas R.”},{“family”:”Erler”,”given”:”Janine T.”},”issued”:{“date-parts”:”2011″,3}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 4.

Cirrhosis is a late stage condition in which the architecture of the liver becomes abnormal, the function of hepatocytes is reduced, and the hepatic blood ?ow is altered due to vascularized ?brotic septa surrounding regenerating nodules. Liver cirrhosis results in multiple complications such as coagulation defect and portal hypertension, including ascites, variceal bleeding, renal failure, hepatic encephalopathy, bacterial peritonitis and finally hepatocellular carcinoma ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”d9qH8zwQ”,”properties”:{“formattedCitation”:”3″,”plainCitation”:”3″,”noteIndex”:0},”citationItems”:{“id”:78,”uris”:”http://zotero.org/users/local/dX36zxw6/items/6PR3LU25″,”uri”:”http://zotero.org/users/local/dX36zxw6/items/6PR3LU25″,”itemData”:{“id”:78,”type”:”article-journal”,”title”:”Cellular mechanisms of tissue fibrosis. 5. Novel insights into liver fibrosis”,”container-title”:”American Journal of Physiology. Cell Physiology”,”page”:”C789-799″,”volume”:”305″,”issue”:”8″,”source”:”PubMed”,”abstract”:”Liver fibrosis is the common scarring reaction associated with chronic liver injury that results from prolonged parenchymal cell injury and/or inflammation. The fibrogenic response is characterized by progressive accumulation of extracellular matrix components enriched in fibrillar collagens and a failure of matrix turnover. This process is driven by a heterogeneous population of hepatic myofibroblasts, which mainly derive from hepatic stellate cells and portal fibroblasts. Regression of fibrosis can be achieved by the successful control of chronic liver injury, owing to termination of the fibrogenic reaction following clearance of hepatic myofibroblasts and restoration of fibrolytic pathways. Understanding of the complex network underlying liver fibrogenesis has allowed the identification of a large number of antifibrotic targets, but no antifibrotic drug has as yet been approved. This review will highlight recent advances regarding the mechanisms that regulate liver fibrogenesis and fibrosis regression, with special focus on novel signaling pathways and the role of inflammatory cells. Translation of these findings to therapies will require continued efforts to develop multitarget therapeutic approaches that will improve the grim prognosis of liver cirrhosis.”,”DOI”:”10.1152/ajpcell.00230.2013″,”ISSN”:”1522-1563″,”note”:”PMID: 23903700″,”journalAbbreviation”:”Am. J. Physiol., Cell Physiol.”,”language”:”eng”,”author”:{“family”:”Mallat”,”given”:”Ariane”},{“family”:”Lotersztajn”,”given”:”Sophie”},”issued”:{“date-parts”:”2013″,10,15}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 3.

2. Architecture of the normal liver2.1. Anatomy
The liver is the heaviest visceral organ in the body, expressing 2–5% of body weight and exhibits an iterative, multicellular architecture. The organ is divided into four lobes; yet, the liver lobule represents its functional units.

Each lobule is composed of hexagonal cords of hepatocytes arranged around a central vein that drain into the large hepatic vein. The corners of the hexagon constitute the portal triad consisting of a portal vein, hepatic artery and biliary duct ( REF _Ref522294612 h * MERGEFORMAT Figure 1-A). Within a lobule, two afferent vessels supply hepatic blood: the hepatic artery and the portal vein, and flows in specialized sinusoidal vessels towards the central vein ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”ALq4Badn”,”properties”:{“formattedCitation”:”1″,”plainCitation”:”1″,”noteIndex”:0},”citationItems”:{“id”:66,”uris”:”http://zotero.org/users/local/dX36zxw6/items/A29872Z6″,”uri”:”http://zotero.org/users/local/dX36zxw6/items/A29872Z6″,”itemData”:{“id”:66,”type”:”article-journal”,”title”:”Cell and Tissue Engineering for Liver Disease”,”container-title”:”Science translational medicine”,”page”:”245sr2″,”volume”:”6″,”issue”:”245″,”source”:”PubMed Central”,”abstract”:”Despite the tremendous hurdles presented by the complexity of the liver’s structure and function, advances in liver physiology, stem cell biology and reprogramming, and the engineering of tissues and devices are accelerating the development of cell-based therapies for treating liver disease and liver failure. This State of the Art Review discusses both the near and long-term prospects for such cell-based therapies and the unique challenges for clinical translation.”,”DOI”:”10.1126/scitranslmed.3005975″,”ISSN”:”1946-6234″,”note”:”PMID: 25031271
PMCID: PMC4374645″,”journalAbbreviation”:”Sci Transl Med”,”author”:{“family”:”Bhatia”,”given”:”Sangeeta N.”},{“family”:”Underhill”,”given”:”Gregory H.”},{“family”:”Zaret”,”given”:”Kenneth S.”},{“family”:”Fox”,”given”:”Ira J.”},”issued”:{“date-parts”:”2014″,7,16}},”label”:”page”},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 1.

The hepatic sinusoid is a complex vascular channel built from specialized fenestrated endothelial cells of the liver also it is the residence of the hepatic macrophages named Kupffer cells. Stellate cells are located in the sub-endothelial space known as the space of Disse that separates the hepatocyte cords from the blood and the sinusoids (Figure 1-B). Bile, that is produced and excreted by hepatocytes into the bile canaliculi, flows in the opposite direction to sinusoidal blood flow towards the intrahepatic bile duct, which is lined by epithelial cells called cholangiocytes ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”74bJOJza”,”properties”:{“formattedCitation”:”5″,”plainCitation”:”5″,”noteIndex”:0},”citationItems”:{“id”:63,”uris”:”http://zotero.org/users/local/dX36zxw6/items/8VD79RWL”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/8VD79RWL”,”itemData”:{“id”:63,”type”:”article-journal”,”title”:”Orchestrating liver development”,”container-title”:”Development (Cambridge, England)”,”page”:”2094-2108″,”volume”:”142″,”issue”:”12″,”source”:”PubMed Central”,”abstract”:”The liver is a central regulator of metabolism, and liver failure thus constitutes a major health burden. Understanding how this complex organ develops during embryogenesis will yield insights into how liver regeneration can be promoted and how functional liver replacement tissue can be engineered. Recent studies of animal models have identified key signaling pathways and complex tissue interactions that progressively generate liver progenitor cells, differentiated lineages and functional tissues. In addition, progress in understanding how these cells interact, and how transcriptional and signaling programs precisely coordinate liver development, has begun to elucidate the molecular mechanisms underlying this complexity. Here, we review the lineage relationships, signaling pathways and transcriptional programs that orchestrate hepatogenesis., Summary: This review summarises the complex interplay between cellular lineages, signalling pathways, and transcriptional programs necessary to form a vertebrate liver.”,”DOI”:”10.1242/dev.114215″,”ISSN”:”0950-1991″,”note”:”PMID: 26081571
PMCID: PMC4483763″,”journalAbbreviation”:”Development”,”author”:{“family”:”Gordillo”,”given”:”Miriam”},{“family”:”Evans”,”given”:”Todd”},{“family”:”Gouon-Evans”,”given”:”Valerie”},”issued”:{“date-parts”:”2015″,6,15}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 5.

Figure 1: Structure of the healthy liver ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”zxQ3C0uJ”,”properties”:{“formattedCitation”:”5″,”plainCitation”:”5″,”noteIndex”:0},”citationItems”:{“id”:63,”uris”:”http://zotero.org/users/local/dX36zxw6/items/8VD79RWL”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/8VD79RWL”,”itemData”:{“id”:63,”type”:”article-journal”,”title”:”Orchestrating liver development”,”container-title”:”Development (Cambridge, England)”,”page”:”2094-2108″,”volume”:”142″,”issue”:”12″,”source”:”PubMed Central”,”abstract”:”The liver is a central regulator of metabolism, and liver failure thus constitutes a major health burden. Understanding how this complex organ develops during embryogenesis will yield insights into how liver regeneration can be promoted and how functional liver replacement tissue can be engineered. Recent studies of animal models have identified key signaling pathways and complex tissue interactions that progressively generate liver progenitor cells, differentiated lineages and functional tissues. In addition, progress in understanding how these cells interact, and how transcriptional and signaling programs precisely coordinate liver development, has begun to elucidate the molecular mechanisms underlying this complexity. Here, we review the lineage relationships, signaling pathways and transcriptional programs that orchestrate hepatogenesis., Summary: This review summarises the complex interplay between cellular lineages, signalling pathways, and transcriptional programs necessary to form a vertebrate liver.”,”DOI”:”10.1242/dev.114215″,”ISSN”:”0950-1991″,”note”:”PMID: 26081571
PMCID: PMC4483763″,”journalAbbreviation”:”Development”,”author”:{“family”:”Gordillo”,”given”:”Miriam”},{“family”:”Evans”,”given”:”Todd”},{“family”:”Gouon-Evans”,”given”:”Valerie”},”issued”:{“date-parts”:”2015″,6,15}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 5.(A) Geometric organization of the hepatic lobule, the functional unit of the liver. (B) A schematic representation of a sinusoid within the liver and the corresponding location of different hepatic cells.
2.2. FunctionThe liver exhibits many functions in the body, including filtration of the blood, endocrine control of growth signaling pathways and biliary excretion (bile salts and bicarbonate) that facilitates digestion of fats and lipids ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”UW5CgcX4″,”properties”:{“formattedCitation”:”1″,”plainCitation”:”1″,”noteIndex”:0},”citationItems”:{“id”:66,”uris”:”http://zotero.org/users/local/dX36zxw6/items/A29872Z6″,”uri”:”http://zotero.org/users/local/dX36zxw6/items/A29872Z6″,”itemData”:{“id”:66,”type”:”article-journal”,”title”:”Cell and Tissue Engineering for Liver Disease”,”container-title”:”Science translational medicine”,”page”:”245sr2″,”volume”:”6″,”issue”:”245″,”source”:”PubMed Central”,”abstract”:”Despite the tremendous hurdles presented by the complexity of the liver’s structure and function, advances in liver physiology, stem cell biology and reprogramming, and the engineering of tissues and devices are accelerating the development of cell-based therapies for treating liver disease and liver failure. This State of the Art Review discusses both the near and long-term prospects for such cell-based therapies and the unique challenges for clinical translation.”,”DOI”:”10.1126/scitranslmed.3005975″,”ISSN”:”1946-6234″,”note”:”PMID: 25031271
PMCID: PMC4374645″,”journalAbbreviation”:”Sci Transl Med”,”author”:{“family”:”Bhatia”,”given”:”Sangeeta N.”},{“family”:”Underhill”,”given”:”Gregory H.”},{“family”:”Zaret”,”given”:”Kenneth S.”},{“family”:”Fox”,”given”:”Ira J.”},”issued”:{“date-parts”:”2014″,7,16}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 1. The liver also provides immune system support, detoxifies chemicals such as xenobiotics, and metabolizes drugs and macronutrient supplying the body with the needed energy.

Carbohydrate storage as glycogen and glucose manufacture via the gluconeogenic pathway is the most critical liver function, in addition to cholesterol homeostasis, lipids oxidation, and storage of excess lipid in other tissues, such as adipose. Finally, the liver is a major producer of the proteins secreted in the blood, their conversion into amino acids, and removal of nitrogen in the form of urea metabolism ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”DLiHW4RK”,”properties”:{“formattedCitation”:”6″,”plainCitation”:”6″,”noteIndex”:0},”citationItems”:{“id”:86,”uris”:”http://zotero.org/users/local/dX36zxw6/items/7LMTCX9Y”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/7LMTCX9Y”,”itemData”:{“id”:86,”type”:”article-journal”,”title”:”The liver”,”container-title”:”Current Biology”,”page”:”R1147-R1151″,”volume”:”27″,”issue”:”21″,”source”:”ScienceDirect”,”abstract”:”Summary
The liver is a critical hub for numerous physiological processes. These include macronutrient metabolism, blood volume regulation, immune system support, endocrine control of growth signaling pathways, lipid and cholesterol homeostasis, and the breakdown of xenobiotic compounds, including many current drugs. Processing, partitioning, and metabolism of macronutrients provide the energy needed to drive the aforementioned processes and are therefore among the liver’s most critical functions. Moreover, the liver’s capacities to store glucose in the form of glycogen, with feeding, and assemble glucose via the gluconeogenic pathway, in response to fasting, are critical. The liver oxidizes lipids, but can also package excess lipid for secretion to and storage in other tissues, such as adipose. Finally, the liver is a major handler of protein and amino acid metabolism as it is responsible for the majority of proteins secreted in the blood (whether based on mass or range of unique proteins), the processing of amino acids for energy, and disposal of nitrogenous waste from protein degradation in the form of urea metabolism. Over the course of evolution this array of hepatic functions has been consolidated in a single organ, the liver, which is conserved in all vertebrates. Developmentally, this organ arises as a result of a complex differentiation program that is initiated by exogenous signal gradients, cellular localization cues, and an intricate hierarchy of transcription factors. These processes that are fully developed in the mature liver are imperative for life. Liver failure from any number of sources (e.g. viral infection, overnutrition, or oncologic burden) is a global health problem. The goal of this primer is to concisely summarize hepatic functions with respect to macronutrient metabolism. Introducing concepts critical to liver development, organization, and physiology sets the stage for these functions and serves to orient the reader. It is important to emphasize that insight into hepatic pathologies and potential therapeutic avenues to treat these conditions requires an understanding of the development and physiology of specialized hepatic functions.”,”DOI”:”10.1016/j.cub.2017.09.019″,”ISSN”:”0960-9822″,”journalAbbreviation”:”Current Biology”,”author”:{“family”:”Trefts”,”given”:”Elijah”},{“family”:”Gannon”,”given”:”Maureen”},{“family”:”Wasserman”,”given”:”David H.”},”issued”:{“date-parts”:”2017″,11,6}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 6.
2.3. Cells within the liverThere are four major cell types that play different roles in order to allow the proper functioning of the liver.

2.3.1. HepatocytesHepatocytes are parenchymal cells, consisting 70% of the liver population ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”AlbKoxvs”,”properties”:{“formattedCitation”:”7″,”plainCitation”:”7″,”noteIndex”:0},”citationItems”:{“id”:93,”uris”:”http://zotero.org/users/local/dX36zxw6/items/54SKS8B3″,”uri”:”http://zotero.org/users/local/dX36zxw6/items/54SKS8B3″,”itemData”:{“id”:93,”type”:”article-journal”,”title”:”A Cell-type-resolved Liver Proteome”,”container-title”:”Molecular ; Cellular Proteomics : MCP”,”page”:”3190-3202″,”volume”:”15″,”issue”:”10″,”source”:”PubMed Central”,”abstract”:”Parenchymatous organs consist of multiple cell types, primarily defined as parenchymal cells (PCs) and nonparenchymal cells (NPCs). The cellular characteristics of these organs are not well understood. Proteomic studies facilitate the resolution of the molecular details of different cell types in organs. These studies have significantly extended our knowledge about organogenesis and organ cellular composition. Here, we present an atlas of the cell-type-resolved liver proteome. In-depth proteomics identified 6000 to 8000 gene products (GPs) for each cell type and a total of 10,075 GPs for four cell types. This data set revealed features of the cellular composition of the liver: (1) hepatocytes (PCs) express the least GPs, have a unique but highly homogenous proteome pattern, and execute fundamental liver functions; (2) the division of labor among PCs and NPCs follows a model in which PCs make the main components of pathways, but NPCs trigger the pathways; and (3) crosstalk among NPCs and PCs maintains the PC phenotype. This study presents the liver proteome at cell resolution, serving as a research model for dissecting the cell type constitution and organ features at the molecular level.”,”DOI”:”10.1074/mcp.M116.060145″,”ISSN”:”1535-9476″,”note”:”PMID: 27562671
PMCID: PMC5054343″,”journalAbbreviation”:”Mol Cell Proteomics”,”author”:{“family”:”Ding”,”given”:”Chen”},{“family”:”Li”,”given”:”Yanyan”},{“family”:”Guo”,”given”:”Feifei”},{“family”:”Jiang”,”given”:”Ying”},{“family”:”Ying”,”given”:”Wantao”},{“family”:”Li”,”given”:”Dong”},{“family”:”Yang”,”given”:”Dong”},{“family”:”Xia”,”given”:”Xia”},{“family”:”Liu”,”given”:”Wanlin”},{“family”:”Zhao”,”given”:”Yan”},{“family”:”He”,”given”:”Yangzhige”},{“family”:”Li”,”given”:”Xianyu”},{“family”:”Sun”,”given”:”Wei”},{“family”:”Liu”,”given”:”Qiongming”},{“family”:”Song”,”given”:”Lei”},{“family”:”Zhen”,”given”:”Bei”},{“family”:”Zhang”,”given”:”Pumin”},{“family”:”Qian”,”given”:”Xiaohong”},{“family”:”Qin”,”given”:”Jun”},{“family”:”He”,”given”:”Fuchu”},”issued”:{“date-parts”:”2016″,10}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 7, with an average life expectancy of 5 to 6 months. They are characterized by round nuclei with dispersed chromatin and prominent nucleoli. The cytoplasm comprises numerous mitochondria, rough ER and free ribosomes. Hepatocytes, regulated by the NPCs released factor, have a main role in the basic functions of the liver, and in the metabolic activities mentioned before ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”aOLjQYeW”,”properties”:{“formattedCitation”:”8″,”plainCitation”:”8″,”noteIndex”:0},”citationItems”:{“id”:129,”uris”:”http://zotero.org/users/local/dX36zxw6/items/S8CBJNXP”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/S8CBJNXP”,”itemData”:{“id”:129,”type”:”chapter”,”title”:”Chapter?61 – Liver”,”container-title”:”Canine and Feline Gastroenterology”,”publisher”:”W.B. Saunders”,”publisher-place”:”Saint Louis”,”page”:”849-957″,”source”:”ScienceDirect”,”event-place”:”Saint Louis”,”URL”:”http://www.sciencedirect.com/science/article/pii/B9781416036616000614″,”ISBN”:”978-1-4160-3661-6″,”note”:”DOI: 10.1016/B978-1-4160-3661-6.00061-4″,”editor”:{“family”:”Washabau”,”given”:”Robert J.”},{“family”:”Day”,”given”:”Michael J.”},”issued”:{“date-parts”:”2013″,1,1},”accessed”:{“date-parts”:”2018″,8,21}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 8. NPCs also stimulate the hepatocyte capacity to replicate mentioning that hepatocyte only secrete TGF a as an autocrine growth factor ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”bjtDQe4u”,”properties”:{“formattedCitation”:”9″,”plainCitation”:”9″,”noteIndex”:0},”citationItems”:{“id”:98,”uris”:”http://zotero.org/users/local/dX36zxw6/items/8UNAJQKK”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/8UNAJQKK”,”itemData”:{“id”:98,”type”:”article-journal”,”title”:”The role of hepatocytes and oval cells in liver regeneration and repopulation”,”container-title”:”Mechanisms of Development”,”page”:”117-130″,”volume”:”120″,”issue”:”1″,”source”:”ScienceDirect”,”abstract”:”The liver has the unique capacity to regulate its growth and mass. In rodents and humans, it grows rapidly after resection of more than 50% of its mass. This growth process, as well as that following acute chemical injury is known as liver regeneration, although growth takes place by compensatory hyperplasia rather than true regeneration. In addition to hepatocytes and non-parenchymal cells, the liver contains intra-hepatic “stem” cells which can generate a transit compartment of precursors named oval cells. Liver regeneration after partial hepatectomy does not involve intra or extra-hepatic (hemopoietic) stem cells but depends on the proliferation of hepatocytes. Transplantation and repopulation experiments have demonstrated that hepatocytes, which are highly differentiated and long-lived cells, have a remarkable capacity for multiple rounds of replication. In this article, we review some aspects of the regulation of hepatocyte proliferation as well as the interrelationships between hepatocytes and oval cells in different liver growth processes. We conclude that in the liver, normally quiescent differentiated cells replicate rapidly after tissue resection, while intra-hepatic precursor cells (oval cells) proliferate and generate lineage only in situations in which hepatocyte proliferation is blocked or delayed. Although bone marrow stem cells can generate oval cells and hepatocytes, transdifferentiation is very rare and inefficient.”,”DOI”:”10.1016/S0925-4773(02)00338-6″,”ISSN”:”0925-4773″,”journalAbbreviation”:”Mechanisms of Development”,”author”:{“family”:”Fausto”,”given”:”Nelson”},{“family”:”Campbell”,”given”:”Jean S.”},”issued”:{“date-parts”:”2003″,1,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 9. Regeneration is not the only property that specialize the hepatocyte, 50% of the population possess more than two paired sets of chromosomes, a condition known as Anisokaryosis ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”SSusgKsq”,”properties”:{“formattedCitation”:”8″,”plainCitation”:”8″,”noteIndex”:0},”citationItems”:{“id”:129,”uris”:”http://zotero.org/users/local/dX36zxw6/items/S8CBJNXP”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/S8CBJNXP”,”itemData”:{“id”:129,”type”:”chapter”,”title”:”Chapter?61 – Liver”,”container-title”:”Canine and Feline Gastroenterology”,”publisher”:”W.B. Saunders”,”publisher-place”:”Saint Louis”,”page”:”849-957″,”source”:”ScienceDirect”,”event-place”:”Saint Louis”,”URL”:”http://www.sciencedirect.com/science/article/pii/B9781416036616000614″,”ISBN”:”978-1-4160-3661-6″,”note”:”DOI: 10.1016/B978-1-4160-3661-6.00061-4″,”editor”:{“family”:”Washabau”,”given”:”Robert J.”},{“family”:”Day”,”given”:”Michael J.”},”issued”:{“date-parts”:”2013″,1,1},”accessed”:{“date-parts”:”2018″,8,21}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 8.2.3.2. Kuppfer cells
Kupffer cells are non-parenchymal, resident macrophages which are different from in?ltrating macrophages. They are positioned through the sinusoidal endothelial cells and represent 15% of the total hepatic cells. Kupffer cells are important phagocytes in the liver; they help the innate immune response by scavenging microorganisms that reach the sinusoidal vessels, regulating of inflammatory processes, and finally by removing immune complexes, blood debris and toxic substances. Moreover, kupffer cells regulate iron, bilirubin and cholesterol metabolism.

Furthermore, to be activated, these cells express several receptors; for instance receptor-mediated endocytosis, Fc receptor and Toll-like receptor 4 (TLR4). They also express CD14 and CD68 as surface markers, yet they are negative for CX3CR1. Activation by LPS, DAMPs or complement component leads kypffer cells to release cytokines and chemokines such as CCL2, CCL5, TNF-?, IL-1, IL-6, and reactive oxygen species, promoting the recruitment and activation of other pro-inflammatory cells. In addition, kupffer cells stimulate anti-inflammatory cells by secreting IL-10 specially at the acute phase of liver damage ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”qOG5t765″,”properties”:{“formattedCitation”:”10, 11″,”plainCitation”:”10, 11″,”noteIndex”:0},”citationItems”:{“id”:106,”uris”:”http://zotero.org/users/local/dX36zxw6/items/JT3XLU9U”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/JT3XLU9U”,”itemData”:{“id”:106,”type”:”article-journal”,”title”:”Liver macrophages in tissue homeostasis and disease”,”container-title”:”Nature Reviews Immunology”,”page”:”306-321″,”volume”:”17″,”issue”:”5″,”source”:”www.nature.com”,”abstract”:”Macrophages represent a key cellular component of the liver, and are essential for maintaining tissue homeostasis and ensuring rapid responses to hepatic injury. Our understanding of liver macrophages has been revolutionized by the delineation of heterogeneous subsets of these cells. Kupffer cells are a self-sustaining, liver-resident population of macrophages and can be distinguished from the monocyte-derived macrophages that rapidly accumulate in the injured liver. Specific environmental signals further determine the polarization and function of hepatic macrophages. These cells promote the restoration of tissue integrity following liver injury or infection, but they can also contribute to the progression of liver diseases, including hepatitis, fibrosis and cancer. In this Review, we highlight novel findings regarding the origin, classification and function of hepatic macrophages, and we discuss their divergent roles in the healthy and diseased liver.”,”DOI”:”10.1038/nri.2017.11″,”ISSN”:”1474-1741″,”language”:”en”,”author”:{“family”:”Krenkel”,”given”:”Oliver”},{“family”:”Tacke”,”given”:”Frank”},”issued”:{“date-parts”:”2017″,5}},”label”:”page”},{“id”:110,”uris”:”http://zotero.org/users/local/dX36zxw6/items/AYWRY4PP”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/AYWRY4PP”,”itemData”:{“id”:110,”type”:”article-journal”,”title”:”Understanding the Mechanism of Hepatic Fibrosis and Potential Therapeutic Approaches”,”container-title”:”Saudi Journal of Gastroenterology : Official Journal of the Saudi Gastroenterology Association”,”page”:”155-167″,”volume”:”18″,”issue”:”3″,”source”:”PubMed Central”,”abstract”:”Hepatic fibrosis (HF) is a progressive condition with serious clinical complications arising from abnormal proliferation and amassing of tough fibrous scar tissue. This defiance of collagen fibers becomes fatal due to ultimate failure of liver functions. Participation of various cell types, interlinked cellular events, and large number of mediator molecules make the fibrotic process enormously complex and dynamic. However, with better appreciation of underlying cellular and molecular mechanisms of fibrosis, the assumption that HF cannot be cured is gradually changing. Recent findings have underlined the therapeutic potential of a number of synthetic compounds as well as plant derivatives for cessation or even the reversal of the processes that transforms the liver into fibrotic tissue. It is expected that future inputs will provide a conceptual framework to develop more specific strategies that would facilitate the assessment of risk factors, shortlist early diagnosis biomarkers, and eventually guide development of effective therapeutic alternatives.”,”DOI”:”10.4103/1319-3767.96445″,”ISSN”:”1319-3767″,”note”:”PMID: 22626794
PMCID: PMC3371417″,”journalAbbreviation”:”Saudi J Gastroenterol”,”author”:{“family”:”Ahmad”,”given”:”Areeba”},{“family”:”Ahmad”,”given”:”Riaz”},”issued”:{“date-parts”:”2012″}},”label”:”page”},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 10, 11.
2.3.3. Sinusoidal endothelial cells (SEC)
Liver sinusoidal endothelial cells (LSECs) form the wall of liver sinusoid that separate hepatocytes from the blood. These cells have the highest percentage of the non-parenshymal hepatic cells; comprising about 15% of liver cells and 3% of hepatic volume. Upon their differentiation into adult LSECs, they gain markers such as CD4, CD32 and ICAM-1. Yet, some of these markers are similar to other cells including endothelial and hematopoietic cells but none of them is specific for LSECs ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”md3xeUip”,”properties”:{“formattedCitation”:”12″,”plainCitation”:”12″,”noteIndex”:0},”citationItems”:{“id”:121,”uris”:”http://zotero.org/users/local/dX36zxw6/items/YCZHRX2M”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/YCZHRX2M”,”itemData”:{“id”:121,”type”:”article-journal”,”title”:”Liver sinusoidal endothelial cells: Physiology and role in liver diseases”,”container-title”:”Journal of Hepatology”,”page”:”212-227″,”volume”:”66″,”issue”:”1″,”source”:”www.journal-of-hepatology.eu”,”DOI”:”10.1016/j.jhep.2016.07.009″,”ISSN”:”0168-8278, 1600-0641″,”note”:”PMID: 27423426″,”shortTitle”:”Liver sinusoidal endothelial cells”,”journalAbbreviation”:”Journal of Hepatology”,”language”:”English”,”author”:{“family”:”Poisson”,”given”:”Johanne”},{“family”:”Lemoinne”,”given”:”Sara”},{“family”:”Boulanger”,”given”:”Chantal”},{“family”:”Durand”,”given”:”François”},{“family”:”Moreau”,”given”:”Richard”},{“family”:”Valla”,”given”:”Dominique”},{“family”:”Rautou”,”given”:”Pierre-Emmanuel”},”issued”:{“date-parts”:”2017″,1,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 12.

LSECs represent a permeable barrier which displays distinctive structural features that make them different from other endothelial cells. In fact, not having a basal membrane neither a diaphragm yet possessing of fenestrae make these cells the most permeable cells with the highest endocytosis capacity of any cell in the body ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”tPG3AZsk”,”properties”:{“formattedCitation”:”13″,”plainCitation”:”13″,”noteIndex”:0},”citationItems”:{“id”:126,”uris”:”http://zotero.org/users/local/dX36zxw6/items/S6NVGWQJ”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/S6NVGWQJ”,”itemData”:{“id”:126,”type”:”article-journal”,”title”:”Pathological process of liver sinusoidal endothelial cells in liver diseases”,”container-title”:”World Journal of Gastroenterology”,”page”:”7666-7677″,”volume”:”23″,”issue”:”43″,”source”:”www.wjgnet.com”,”abstract”:”Pathological process of liver sinusoidal endothelial cells in liver diseases”,”DOI”:”10.3748/wjg.v23.i43.7666″,”language”:”en”,”author”:{“family”:”Ni”,”given”:”Yao”},{“family”:”Li”,”given”:”Juan-Mei”},{“family”:”Liu”,”given”:”Ming-Kun”},{“family”:”Zhang”,”given”:”Ting-Ting”},{“family”:”Wang”,”given”:”Dong-Ping”},{“family”:”Zhou”,”given”:”Wen-Hui”},{“family”:”Hu”,”given”:”Ling-Zi”},{“family”:”Lv”,”given”:”Wen-Liang”},”issued”:{“date-parts”:”2017″,11,21}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 13. Also, filtration, recruitment of lymphocytes and antigen presentation are main physiological, scavenger and immunological functions of LSECs. Intrahepatic vasoconstriction and fibrosis progression are inhibited by the LSECs, since they prevent the activation of hepatic stellate cells. Add to the mentioned above, LESCs have their role in liver regeneration following partial hepatectomy and liver injury. However, in case of pathology, they can boost angiogenesis and vasoconstriction by becoming capillarized and dropping their protective features. Thus, the immune homeostasis within the liver is maintained ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”JFyjktYf”,”properties”:{“formattedCitation”:”14″,”plainCitation”:”14″,”noteIndex”:0},”citationItems”:{“id”:119,”uris”:”http://zotero.org/users/local/dX36zxw6/items/Q93PX23L”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/Q93PX23L”,”itemData”:{“id”:119,”type”:”article-journal”,”title”:”Liver sinusoidal endothelial cells — gatekeepers of hepatic immunity”,”container-title”:”Nature Reviews Gastroenterology ; Hepatology”,”page”:”1″,”source”:”www.nature.com”,”abstract”:”Liver sinusoidal endothelial cells (LSECs) represent the most abundant non-parenchymal hepatic cell population. In this Review, the authors explore the key roles that LSECs have in regulating hepatic immunity and their contribution to immune-mediated disease, liver fibrosis and carcinogenesis.”,”DOI”:”10.1038/s41575-018-0020-y”,”ISSN”:”1759-5053″,”language”:”en”,”author”:{“family”:”Shetty”,”given”:”Shishir”},{“family”:”Lalor”,”given”:”Patricia F.”},{“family”:”Adams”,”given”:”David H.”},”issued”:{“date-parts”:”2018″,5,29}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 14
2.3.4. Hepatic Stellate Cells (HSCs)
Hepatic stellate cells, also called fat-storing cells or perisinusoidal lipocytes are considered the main source of ECM during hepatic disease. Having a star-like shape, they originate from mesenshymal lineage and represent 10% of all resident liver cells. HSCs display two distinctive phenotypes; in the normal liver they express a quiescent phenotype to be activated in case of injury ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”Yx8HuwXv”,”properties”:{“formattedCitation”:”3″,”plainCitation”:”3″,”noteIndex”:0},”citationItems”:{“id”:78,”uris”:”http://zotero.org/users/local/dX36zxw6/items/6PR3LU25″,”uri”:”http://zotero.org/users/local/dX36zxw6/items/6PR3LU25″,”itemData”:{“id”:78,”type”:”article-journal”,”title”:”Cellular mechanisms of tissue fibrosis. 5. Novel insights into liver fibrosis”,”container-title”:”American Journal of Physiology. Cell Physiology”,”page”:”C789-799″,”volume”:”305″,”issue”:”8″,”source”:”PubMed”,”abstract”:”Liver fibrosis is the common scarring reaction associated with chronic liver injury that results from prolonged parenchymal cell injury and/or inflammation. The fibrogenic response is characterized by progressive accumulation of extracellular matrix components enriched in fibrillar collagens and a failure of matrix turnover. This process is driven by a heterogeneous population of hepatic myofibroblasts, which mainly derive from hepatic stellate cells and portal fibroblasts. Regression of fibrosis can be achieved by the successful control of chronic liver injury, owing to termination of the fibrogenic reaction following clearance of hepatic myofibroblasts and restoration of fibrolytic pathways. Understanding of the complex network underlying liver fibrogenesis has allowed the identification of a large number of antifibrotic targets, but no antifibrotic drug has as yet been approved. This review will highlight recent advances regarding the mechanisms that regulate liver fibrogenesis and fibrosis regression, with special focus on novel signaling pathways and the role of inflammatory cells. Translation of these findings to therapies will require continued efforts to develop multitarget therapeutic approaches that will improve the grim prognosis of liver cirrhosis.”,”DOI”:”10.1152/ajpcell.00230.2013″,”ISSN”:”1522-1563″,”note”:”PMID: 23903700″,”journalAbbreviation”:”Am. J. Physiol., Cell Physiol.”,”language”:”eng”,”author”:{“family”:”Mallat”,”given”:”Ariane”},{“family”:”Lotersztajn”,”given”:”Sophie”},”issued”:{“date-parts”:”2013″,10,15}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 3.
Having in their cytoplasm plentiful lipid droplets, containing retinoid, triglyceride, cholesterol, and free fatty acids is the most typical feature of these cells. Furthermore, HSCs present a microfilament cluster of actin and cytoskeletal proteins such as the desmin, vimentin, and synemin. The expression of hepatocyte growth factor (HGF), TGF-b, insulin-like growth factor-I (IGF-I) is also regulated by these cells.

Quiescent HSCs are characterized by myofibroblastic and neurondocrine markers such as PDGFR?, LRAT, GFAP, NGF, NT-3, NCAM and BDNF. They also express synaptophysin, Lhx2 to maintain quiescent and PPAR-g; a transcriptional regulator for adipogenesis and transcriptional inhibitor of type I collagen. Yet, the phenotype misses the expression of fatty acid synthase (FAS) andreceptor CD95.

Following liver injury, activated HSCs become the major source of ECM deposition, by trans-differentiating from vitamin-A storing cells to myofibroblasts, causing increased production of ?SMA (?-smooth muscle actin). Activated HSCs express markers such reelin, the protease P100, cytoglobin, -2 macroglobin. This phenotype’s gene expression is controlled by several transcription factors such as FoxO, ILK and PPAR-?. They are characterized by the loss of retinoids and lipid droplets, increased ability to proliferate, changing the expression of L-type type voltage-operated Ca2+ channels resulting cellular contraction. Finally, HSCs stimulate the chemotactic and inflammatory process within the liver ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”5YEuZFoz”,”properties”:{“formattedCitation”:”11, 15\uc0\u8211{}17″,”plainCitation”:”11, 15–17″,”noteIndex”:0},”citationItems”:{“id”:110,”uris”:”http://zotero.org/users/local/dX36zxw6/items/AYWRY4PP”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/AYWRY4PP”,”itemData”:{“id”:110,”type”:”article-journal”,”title”:”Understanding the Mechanism of Hepatic Fibrosis and Potential Therapeutic Approaches”,”container-title”:”Saudi Journal of Gastroenterology : Official Journal of the Saudi Gastroenterology Association”,”page”:”155-167″,”volume”:”18″,”issue”:”3″,”source”:”PubMed Central”,”abstract”:”Hepatic fibrosis (HF) is a progressive condition with serious clinical complications arising from abnormal proliferation and amassing of tough fibrous scar tissue. This defiance of collagen fibers becomes fatal due to ultimate failure of liver functions. Participation of various cell types, interlinked cellular events, and large number of mediator molecules make the fibrotic process enormously complex and dynamic. However, with better appreciation of underlying cellular and molecular mechanisms of fibrosis, the assumption that HF cannot be cured is gradually changing. Recent findings have underlined the therapeutic potential of a number of synthetic compounds as well as plant derivatives for cessation or even the reversal of the processes that transforms the liver into fibrotic tissue. It is expected that future inputs will provide a conceptual framework to develop more specific strategies that would facilitate the assessment of risk factors, shortlist early diagnosis biomarkers, and eventually guide development of effective therapeutic alternatives.”,”DOI”:”10.4103/1319-3767.96445″,”ISSN”:”1319-3767″,”note”:”PMID: 22626794
PMCID: PMC3371417″,”journalAbbreviation”:”Saudi J Gastroenterol”,”author”:{“family”:”Ahmad”,”given”:”Areeba”},{“family”:”Ahmad”,”given”:”Riaz”},”issued”:{“date-parts”:”2012″}},”label”:”page”},{“id”:143,”uris”:”http://zotero.org/users/local/dX36zxw6/items/QZYLFC8M”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/QZYLFC8M”,”itemData”:{“id”:143,”type”:”article-journal”,”title”:”Origins and functions of liver myofibroblasts”,”container-title”:”Biochimica et Biophysica Acta (BBA) – Molecular Basis of Disease”,”collection-title”:”Fibrosis: Translation of basic research to human disease”,”page”:”948-954″,”volume”:”1832″,”issue”:”7″,”source”:”ScienceDirect”,”abstract”:”Myofibroblasts combine the matrix-producing functions of fibroblasts and the contractile properties of smooth muscle cells. They are the main effectors of fibrosis in all tissues and make a major contribution to other aspects of the wound healing response, including regeneration and angiogenesis. They display the de novo expression of ?-smooth muscle actin. Myofibroblasts, which are absent from the normal liver, are derived from two major sources: hepatic stellate cells (HSCs) and portal mesenchymal cells in the injured liver. Reliable markers for distinguishing between the two subpopulations at the myofibroblast stage are currently lacking, but there is evidence to suggest that both myofibroblast cell types, each exposed to a particular microenvironment (e.g. hypoxia for HSC-MFs, ductular reaction for portal mesenchymal cell-derived myofibroblasts (PMFs)), expand and exert specialist functions, in scarring and inflammation for PMFs, and in vasoregulation and hepatocellular healing for HSC-MFs. Angiogenesis is a major mechanism by which myofibroblasts contribute to the progression of fibrosis in liver disease. It has been clearly demonstrated that liver fibrosis can regress, and this process involves a deactivation of myofibroblasts, although probably not to a fully quiescent phenotype. This article is part of a Special Issue entitled: Fibrosis: Translation of basic research to human disease.”,”DOI”:”10.1016/j.bbadis.2013.02.019″,”ISSN”:”0925-4439″,”journalAbbreviation”:”Biochimica et Biophysica Acta (BBA) – Molecular Basis of Disease”,”author”:{“family”:”Lemoinne”,”given”:”Sara”},{“family”:”Cadoret”,”given”:”Axelle”},{“family”:”El Mourabit”,”given”:”Haquima”},{“family”:”Thabut”,”given”:”Dominique”},{“family”:”Housset”,”given”:”Chantal”},”issued”:{“date-parts”:”2013″,7,1}},”label”:”page”},{“id”:138,”uris”:”http://zotero.org/users/local/dX36zxw6/items/HYWMKRKV”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/HYWMKRKV”,”itemData”:{“id”:138,”type”:”article-journal”,”title”:”Morphological characterisation of portal myofibroblasts and hepatic stellate cells in the normal dog liver”,”container-title”:”Comparative Hepatology”,”page”:”7″,”volume”:”5″,”issue”:”1″,”source”:”BioMed Central”,”abstract”:”Hepatic fibrosis is a common outcome of hepatic injury in both man and dog. Activated fibroblasts which develop myofibroblastic characteristics play an essential role in hepatic fibrogenesis, and are comprised of three subpopulations: 1) portal or septal myofibroblasts, 2) interface myofibroblasts and 3) the perisinusoidally located hepatic stellate cells (HSC). The present study was performed to investigate the immunohistochemical characteristics of canine portal myofibroblasts (MF) and HSC in the normal unaffected liver as a basis for further studies on fibrogenesis in canine liver disease.”,”DOI”:”10.1186/1476-5926-5-7″,”ISSN”:”1476-5926″,”journalAbbreviation”:”Comparative Hepatology”,”author”:{“family”:”IJzer”,”given”:”Jooske”},{“family”:”Roskams”,”given”:”Tania”},{“family”:”Molenbeek”,”given”:”Ronald F.”},{“family”:”Ultee”,”given”:”Ton”},{“family”:”Penning”,”given”:”Louis C.”},{“family”:”Rothuizen”,”given”:”Jan”},{“family”:”Ingh”,”given”:”Ted SGAM”,”non-dropping-particle”:”van den”},”issued”:{“date-parts”:”2006″,11,16}},”label”:”page”},{“id”:131,”uris”:”http://zotero.org/users/local/dX36zxw6/items/WWG4JJ5Y”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/WWG4JJ5Y”,”itemData”:{“id”:131,”type”:”article-journal”,”title”:”Mechanisms of hepatic stellate cell activation”,”container-title”:”Nature Reviews. Gastroenterology ; Hepatology”,”page”:”397-411″,”volume”:”14″,”issue”:”7″,”source”:”PubMed”,”abstract”:”Hepatic fibrosis is a dynamic process characterized by the net accumulation of extracellular matrix resulting from chronic liver injury of any aetiology, including viral infection, alcoholic liver disease and NASH. Activation of hepatic stellate cells (HSCs) – transdifferentiation of quiescent, vitamin-A-storing cells into proliferative, fibrogenic myo?broblasts – is now well established as a central driver of fibrosis in experimental and human liver injury. Yet, the continued discovery of novel pathways and mediators, including autophagy, endoplasmic reticulum stress, oxidative stress, retinol and cholesterol metabolism, epigenetics and receptor-mediated signals, reveals the complexity of HSC activation. Extracellular signals from resident and inflammatory cells including macrophages, hepatocytes, liver sinusoidal endothelial cells, natural killer cells, natural killer T cells, platelets and B cells further modulate HSC activation. Finally, pathways of HSC clearance have been greatly clarified, and include apoptosis, senescence and reversion to an inactivated state. Collectively, these findings reinforce the remarkable complexity and plasticity of HSC activation, and underscore the value of clarifying its regulation in hopes of advancing the development of novel diagnostics and therapies for liver disease.”,”DOI”:”10.1038/nrgastro.2017.38″,”ISSN”:”1759-5053″,”note”:”PMID: 28487545″,”journalAbbreviation”:”Nat Rev Gastroenterol Hepatol”,”language”:”eng”,”author”:{“family”:”Tsuchida”,”given”:”Takuma”},{“family”:”Friedman”,”given”:”Scott L.”},”issued”:{“date-parts”:”2017″,7}},”label”:”page”},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 11, 15–17.

Besides HSCs, portal fibroblastes (PFs) have also a mesenshymal origin. PFs multiply around bile ducts during fibrosis through biliary and cholestatic liver diseases and appear in portal areas and in newly formed fibrous septa. Both cell types show common characteristics in terms of fibrogenic functions also they express similar markers however, there is specific markers that could distinguish between HSCs and PFs. yet, proteomic analysis confirm that cytoglobin is the best over expressed marker in HSCs that differentiate these cells. In addition, PFs have elevated resistance to apoptosis and importante proliferative capacity ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”yFLruYe0″,”properties”:{“formattedCitation”:”18″,”plainCitation”:”18″,”noteIndex”:0},”citationItems”:{“id”:177,”uris”:”http://zotero.org/users/local/dX36zxw6/items/PLDNUXFL”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/PLDNUXFL”,”itemData”:{“id”:177,”type”:”article-journal”,”title”:”Distinct proteomic features of two fibrogenic liver cell populations: hepatic stellate cells and portal myofibroblasts”,”container-title”:”Proteomics”,”page”:”1017-1028″,”volume”:”10″,”issue”:”5″,”source”:”PubMed”,”abstract”:”In chronic liver diseases, the accumulation of extracellular matrix leading to fibrosis is caused by myofibroblasts, the origins of which are debatable. We performed a comparative proteomic study to identify markers and gain insight into distinct functions of myofibroblasts derived either from hepatic stellate cells (HSCs) or from portal mesenchymal cells. After isolation from normal liver and culture in similar conditions, myofibroblastic HSCs (MF-HSCs) presented enlarged cytoplasms whereas portal myofibroblasts (PMFs) were more proliferative, and formed more stress fibers. The two cell types were subjected to comparative analyses by 2-D MS/MS. Six proteins were overexpressed in PMFs, with myofibroblast-related typical functions. Among them, cofilin-1 showed the greatest difference in expression and a lower pI than expected. Immunoblot demonstrated higher levels of phosphorylation, a modification of the protein implicated in stress fiber formation. Eleven proteins, mostly involved in stress response, were overexpressed in MF-HSCs. Cytoglobin had the highest level of overexpression, as confirmed by reverse transcription quantitative real-time PCR, immunoblot and immunocytochemical analyses. These results identify cytoglobin as the best marker for distinguishing MF-HSCs from PMFs and suggest different functions for the two cell populations in the liver wound healing response, with a prominent role for PMFs in scar formation.”,”DOI”:”10.1002/pmic.200900257″,”ISSN”:”1615-9861″,”note”:”PMID: 20049859″,”shortTitle”:”Distinct proteomic features of two fibrogenic liver cell populations”,”journalAbbreviation”:”Proteomics”,”language”:”eng”,”author”:{“family”:”Bosselut”,”given”:”Nelly”},{“family”:”Housset”,”given”:”Chantal”},{“family”:”Marcelo”,”given”:”Paulo”},{“family”:”Rey”,”given”:”Colette”},{“family”:”Burmester”,”given”:”Thorsten”},{“family”:”Vinh”,”given”:”Jöelle”},{“family”:”Vaubourdolle”,”given”:”Michel”},{“family”:”Cadoret”,”given”:”Axelle”},{“family”:”Baudin”,”given”:”Bruno”},”issued”:{“date-parts”:”2010″,3}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 18.

2.4. The liver in health and diseaseGenerally, disturbance of liver’s morphology and function initiate with the injured hepatocytes, once they stimulate the pro-inflammatory pathway. Activated kupffer cells release pro-fibrotic mediators that change the phenotype of HSCs from quiescent to activated cells, resulting in scar formation. The accumulation of extracellular matrix proteins is responsible for the disappearance of endothelial fenestrae and the loss of hepatocytes microvilli (Figure 2) ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”0jm5zeRM”,”properties”:{“formattedCitation”:”19″,”plainCitation”:”19″,”noteIndex”:0},”citationItems”:{“id”:88,”uris”:”http://zotero.org/users/local/dX36zxw6/items/X79E99UB”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/X79E99UB”,”itemData”:{“id”:88,”type”:”article-journal”,”title”:”Models of liver fibrosis: exploring the dynamic nature of inflammation and repair in a solid organ”,”container-title”:”Journal of Clinical Investigation”,”page”:”539-548″,”volume”:”117″,”issue”:”3″,”source”:”PubMed Central”,”abstract”:”Models of liver fibrosis, which include cell culture models, explanted and biopsied human material, and experimental animal models, have demonstrated that liver fibrosis is a highly dynamic example of solid organ wound healing. Recent work in human and animal models has shown that liver fibrosis is potentially reversible and, in specific circumstances, demonstrates resolution with a restoration of near normal architecture. This Review highlights the manner in which studies of models of liver fibrosis have contributed to the paradigm of dynamic wound healing in this solid organ.”,”DOI”:”10.1172/JCI30542″,”ISSN”:”0021-9738″,”note”:”PMID: 17332881
PMCID: PMC1804370″,”shortTitle”:”Models of liver fibrosis”,”journalAbbreviation”:”J Clin Invest”,”author”:{“family”:”Iredale”,”given”:”John P.”},”issued”:{“date-parts”:”2007″,3,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 19.

Figure 2: Cellular modifications in the sinusoid during liver injury ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”gNeeDt48″,”properties”:{“formattedCitation”:”19″,”plainCitation”:”19″,”noteIndex”:0},”citationItems”:{“id”:88,”uris”:”http://zotero.org/users/local/dX36zxw6/items/X79E99UB”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/X79E99UB”,”itemData”:{“id”:88,”type”:”article-journal”,”title”:”Models of liver fibrosis: exploring the dynamic nature of inflammation and repair in a solid organ”,”container-title”:”Journal of Clinical Investigation”,”page”:”539-548″,”volume”:”117″,”issue”:”3″,”source”:”PubMed Central”,”abstract”:”Models of liver fibrosis, which include cell culture models, explanted and biopsied human material, and experimental animal models, have demonstrated that liver fibrosis is a highly dynamic example of solid organ wound healing. Recent work in human and animal models has shown that liver fibrosis is potentially reversible and, in specific circumstances, demonstrates resolution with a restoration of near normal architecture. This Review highlights the manner in which studies of models of liver fibrosis have contributed to the paradigm of dynamic wound healing in this solid organ.”,”DOI”:”10.1172/JCI30542″,”ISSN”:”0021-9738″,”note”:”PMID: 17332881
PMCID: PMC1804370″,”shortTitle”:”Models of liver fibrosis”,”journalAbbreviation”:”J Clin Invest”,”author”:{“family”:”Iredale”,”given”:”John P.”},”issued”:{“date-parts”:”2007″,3,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 19.3. Pathway of liver fibrosis
Figure 3:3.1. Composition and remodeling of ECM3.2. Immune response3.2.1 Activation of HSC
3.2.2 Hepatocytes apoptosis
3.3. Profibrotic mediators4. Regression of fibrosisLiver fibrosis was thought to be irreversible. However, it was proven wrong. In fact, after the cause of injury is removed, regression of hepatic fibrosis happens ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”VaRoqiNw”,”properties”:{“formattedCitation”:”20″,”plainCitation”:”20″,”noteIndex”:0},”citationItems”:{“id”:179,”uris”:”http://zotero.org/users/local/dX36zxw6/items/3ZB5C4FE”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/3ZB5C4FE”,”itemData”:{“id”:179,”type”:”article-journal”,”title”:”Liver fibrosis: Which mechanisms matter?”,”container-title”:”Clinical Liver Disease”,”page”:”94-99″,”volume”:”8″,”issue”:”4″,”source”:”Wiley Online Library”,”abstract”:”Watch a video presentation of this article Watch the interview with the author”,”DOI”:”10.1002/cld.581″,”ISSN”:”2046-2484″,”shortTitle”:”Liver fibrosis”,”language”:”en”,”author”:{“family”:”Weiskirchen”,”given”:”Ralf”},{“family”:”Tacke”,”given”:”Frank”},”issued”:{“date-parts”:”2016″,10,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 20. Liver can revert to a normal architecture although fibrogenesis is not fully reversible in patients with cirrhosis ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”Jun9Tkg2″,”properties”:{“formattedCitation”:”21″,”plainCitation”:”21″,”noteIndex”:0},”citationItems”:{“id”:182,”uris”:”http://zotero.org/users/local/dX36zxw6/items/F5Q2NIFU”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/F5Q2NIFU”,”itemData”:{“id”:182,”type”:”article-journal”,”title”:”Liver fibrosis and repair: immune regulation of wound healing in a solid organ”,”container-title”:”Nature Reviews Immunology”,”page”:”181-194″,”volume”:”14″,”issue”:”3″,”source”:”www.nature.com”,”abstract”:”Fibrosis is a highly conserved and co-ordinated protective response to tissue injury. The interaction of multiple pathways, molecules and systems determines whether fibrosis is self-limiting and homeostatic, or whether it is uncontrolled and excessive. Immune cells have been identified as key players in this fibrotic cascade, with the capacity to exert either injury-inducing or repair-promoting effects. A multi-organ approach was recently suggested to identify the core and regulatory pathways in fibrosis, with the aim of integrating the wealth of information emerging from basic fibrosis research. In this Review, we focus on recent advances in liver fibrosis research as a paradigm for wound healing in solid organs and the role of the immune system in regulating and balancing this response.”,”DOI”:”10.1038/nri3623″,”ISSN”:”1474-1741″,”shortTitle”:”Liver fibrosis and repair”,”language”:”en”,”author”:{“family”:”Pellicoro”,”given”:”Antonella”},{“family”:”Ramachandran”,”given”:”Prakash”},{“family”:”Iredale”,”given”:”John P.”},{“family”:”Fallowfield”,”given”:”Jonathan A.”},”issued”:{“date-parts”:”2014″,3}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 21. Fibrosis regression occurs if activated HSCs undergo apoptosis, senescence and inactivation and finally if the extracellular matrix is degraded.

4.1 Extracellular matrix degradationThe fundamentally step for attaining resolution of fibrosis is the degradation of the extracellular matrix. Yet, this mechanism depends on the activity of ECM degrading MMPs, however, continued and prolonged expression of TIMPs inhibits MMPs function. During liver regression the balance of MMP-TIMP is altered resulting an increased MMP activity, reduced TIMP level and simultaneously degradation of extracellular matrix ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”eQeJYHxm”,”properties”:{“formattedCitation”:”22″,”plainCitation”:”22″,”noteIndex”:0},”citationItems”:{“id”:112,”uris”:”http://zotero.org/users/local/dX36zxw6/items/6J88KX2A”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/6J88KX2A”,”itemData”:{“id”:112,”type”:”article-journal”,”title”:”Regression of Liver Fibrosis”,”container-title”:”Seminars in Liver Disease”,”page”:”1-10″,”volume”:”37″,”issue”:”1″,”source”:”PubMed”,”abstract”:”Liver fibrosis is the final common pathway of chronic or iterative liver damage. Advanced chronic fibrosis is described as cirrhosis with a loss of architecture and attendant functional failure and the development of life-threatening complications. However, compelling evidence from rodent models and human studies indicates that if the injury is removed liver fibrosis is reversible. Hepatocytes, activated hepatic stellate cells, endothelial and immune cells, particularly macrophages, cooperate in the establishment and resolution of liver fibrosis. Here the authors provide a short overview of the mechanisms regulating the profibrotic and proresolution response, with the aim of highlighting potential new therapeutic targets. Liver disease is a major unmet medical need; currently, the sole approaches are the withdrawal of the injurious stimulus and liver transplantation. The authors conclude with a brief review of the feasibility of macrophage-based cell therapy for liver fibrosis.”,”DOI”:”10.1055/s-0036-1597816″,”ISSN”:”1098-8971″,”note”:”PMID: 28201843″,”journalAbbreviation”:”Semin. Liver Dis.”,”language”:”eng”,”author”:{“family”:”Campana”,”given”:”Lara”},{“family”:”Iredale”,”given”:”John P.”},”issued”:{“date-parts”:”2017″}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 22. In vivo studies of the reversibility of hepatic fibrosis in rats, demonstrated that levels of TIMP1 is reduced after the cause of injury was removed. This decrease comes along with an increase of hepatic collagenase activity. This turnover indicates that the liver has significant permanent protease activity ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”6QZlpmEM”,”properties”:{“formattedCitation”:”21″,”plainCitation”:”21″,”noteIndex”:0},”citationItems”:{“id”:182,”uris”:”http://zotero.org/users/local/dX36zxw6/items/F5Q2NIFU”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/F5Q2NIFU”,”itemData”:{“id”:182,”type”:”article-journal”,”title”:”Liver fibrosis and repair: immune regulation of wound healing in a solid organ”,”container-title”:”Nature Reviews Immunology”,”page”:”181-194″,”volume”:”14″,”issue”:”3″,”source”:”www.nature.com”,”abstract”:”Fibrosis is a highly conserved and co-ordinated protective response to tissue injury. The interaction of multiple pathways, molecules and systems determines whether fibrosis is self-limiting and homeostatic, or whether it is uncontrolled and excessive. Immune cells have been identified as key players in this fibrotic cascade, with the capacity to exert either injury-inducing or repair-promoting effects. A multi-organ approach was recently suggested to identify the core and regulatory pathways in fibrosis, with the aim of integrating the wealth of information emerging from basic fibrosis research. In this Review, we focus on recent advances in liver fibrosis research as a paradigm for wound healing in solid organs and the role of the immune system in regulating and balancing this response.”,”DOI”:”10.1038/nri3623″,”ISSN”:”1474-1741″,”shortTitle”:”Liver fibrosis and repair”,”language”:”en”,”author”:{“family”:”Pellicoro”,”given”:”Antonella”},{“family”:”Ramachandran”,”given”:”Prakash”},{“family”:”Iredale”,”given”:”John P.”},{“family”:”Fallowfield”,”given”:”Jonathan A.”},”issued”:{“date-parts”:”2014″,3}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 21. However, resistance to matrix degradation during advanced fibrosis may be caused by collagen cross-linking preventing proteolytic cleavage of collagens, and by deposition of elastin ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”x65e1Mqe”,”properties”:{“formattedCitation”:”23″,”plainCitation”:”23″,”noteIndex”:0},”citationItems”:{“id”:194,”uris”:”http://zotero.org/users/local/dX36zxw6/items/IF8Q3TR9″,”uri”:”http://zotero.org/users/local/dX36zxw6/items/IF8Q3TR9″,”itemData”:{“id”:194,”type”:”article-journal”,”title”:”Mechanisms of liver fibrosis resolution”,”container-title”:”Journal of Hepatology”,”page”:”1038-1039″,”volume”:”63″,”issue”:”4″,”source”:”PubMed”,”DOI”:”10.1016/j.jhep.2015.03.039″,”ISSN”:”1600-0641″,”note”:”PMID: 26232376″,”journalAbbreviation”:”J. Hepatol.”,”language”:”eng”,”author”:{“family”:”Tacke”,”given”:”Frank”},{“family”:”Trautwein”,”given”:”Christian”},”issued”:{“date-parts”:”2015″,10}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 23.

4.2 HSCs apoptosisApoptosis of hepatic stellate cells is mediated by either death receptors-mediated pathway or by pro-apoptotic proteins increased expression, while the expression of pro-survival proteins is decreased ( REF _Ref523382813 h Figure 4). Indeed, HSCs express several death receptors such as FAS, TNFR1, P75 and TRAIL as well as their ligands; FASL, TNF, NGF (nerve growth factor) and TRAIL respectively. Death receptors induce apoptosis by classical caspase activation. Furthermore, caspase-9-mediated programmed cell death results from significant expression of pro-apoptotic proteins such as Bcl, Bax and p53. Immune cells also contribute to the HSCs removal. Natural killer (NK) cells and ?? T (NKT) are involved in the restoration of hepatic fibrosis by killing HSCs when activated by interferon-? (IFN-?). Finally, deprevation of fibrogenic and anti-apoptotic factors is a key mechanism in fibrosis resolution. In fact, Resistance to apoptosis is an important feature of activated HSCs which may due to the survival signals expressed by protein kinases and NF-?B cascade, in addition to anti-apoptotic cytokines such as TIMP1 and TGF? ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”IYMnC8DA”,”properties”:{“formattedCitation”:”21, 24″,”plainCitation”:”21, 24″,”noteIndex”:0},”citationItems”:{“id”:182,”uris”:”http://zotero.org/users/local/dX36zxw6/items/F5Q2NIFU”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/F5Q2NIFU”,”itemData”:{“id”:182,”type”:”article-journal”,”title”:”Liver fibrosis and repair: immune regulation of wound healing in a solid organ”,”container-title”:”Nature Reviews Immunology”,”page”:”181-194″,”volume”:”14″,”issue”:”3″,”source”:”www.nature.com”,”abstract”:”Fibrosis is a highly conserved and co-ordinated protective response to tissue injury. The interaction of multiple pathways, molecules and systems determines whether fibrosis is self-limiting and homeostatic, or whether it is uncontrolled and excessive. Immune cells have been identified as key players in this fibrotic cascade, with the capacity to exert either injury-inducing or repair-promoting effects. A multi-organ approach was recently suggested to identify the core and regulatory pathways in fibrosis, with the aim of integrating the wealth of information emerging from basic fibrosis research. In this Review, we focus on recent advances in liver fibrosis research as a paradigm for wound healing in solid organs and the role of the immune system in regulating and balancing this response.”,”DOI”:”10.1038/nri3623″,”ISSN”:”1474-1741″,”shortTitle”:”Liver fibrosis and repair”,”language”:”en”,”author”:{“family”:”Pellicoro”,”given”:”Antonella”},{“family”:”Ramachandran”,”given”:”Prakash”},{“family”:”Iredale”,”given”:”John P.”},{“family”:”Fallowfield”,”given”:”Jonathan A.”},”issued”:{“date-parts”:”2014″,3}},”label”:”page”},{“id”:198,”uris”:”http://zotero.org/users/local/dX36zxw6/items/MWMVM7LB”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/MWMVM7LB”,”itemData”:{“id”:198,”type”:”article-journal”,”title”:”Reversibility of Liver Fibrosis”,”container-title”:”Clinics and research in hepatology and gastroenterology”,”page”:”S60-S63″,”volume”:”39″,”issue”:”0 1″,”source”:”PubMed Central”,”abstract”:”Liver fibrosis is a serious health problem worldwide, which can be induced by a wide spectrum of chronic liver injuries. However, until today, there is no effective therapy available for liver fibrosis except the removal of underlying etiology or liver transplantation. Recent studies indicate that liver fibrosis is reversible when the causative agent (s) is removed. Understanding of mechanisms of liver fibrosis regression will lead to the identification of new therapeutic targets for liver fibrosis. This review summarizes recent research progress on mechanisms of reversibility of liver fibrosis., While most of the research has been focused on HSCs/myofibroblasts and inflammatory pathways, the crosstalk between different organs, various cell types and multiple signaling pathways should not be overlooked. Future studies that lead to fully understanding of the crosstalk between different cell types and the molecular mechanism underlying the reversibility of liver fibrosis will definitely give rise to new therapeutic strategies to treat liver fibrosis.”,”DOI”:”10.1016/j.clinre.2015.06.015″,”ISSN”:”2210-7401″,”note”:”PMID: 26206574
PMCID: PMC4636085″,”journalAbbreviation”:”Clin Res Hepatol Gastroenterol”,”author”:{“family”:”Sun”,”given”:”Mengxi”},{“family”:”Kisseleva”,”given”:”Tatiana”},”issued”:{“date-parts”:”2015″,9}},”label”:”page”},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 21, 24.

4.3 HSCs senescence
Senescence is a phenotype associated with irreversible permanent cell-cycle arrest by which cells stop dividing without undergoing cell death,. Interestingly, studies have confirmed that some of activated HSCs in rodent and human hepatic ?brosis express senescence markers like p53.

P53 knockout mice had increased HSCs proliferations and worsened liver fibrosis in response to CCl4. In addition, cessation of CCl4 did not limit HSCs activation, preventing scar resolution. Suggesting that during hepatic fibrosis, senescence is essential in the removal of hepatic stellate cells. Also, in vitro study showed a decreased level of ECM components associated with an up regulation of MMPs expression and genes of immune surveillance, when HSCs access a senescent phenotype. Other studies indicate that senescent HSCs are deleted by NK cells ( REF _Ref523382813 h Figure 4) ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”Rc9AGrlT”,”properties”:{“formattedCitation”:”25″,”plainCitation”:”25″,”noteIndex”:0},”citationItems”:{“id”:202,”uris”:”http://zotero.org/users/local/dX36zxw6/items/QEDN64HU”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/QEDN64HU”,”itemData”:{“id”:202,”type”:”article-journal”,”title”:”Senescence of activated stellate cells limits liver fibrosis”,”container-title”:”Cell”,”page”:”657-667″,”volume”:”134″,”issue”:”4″,”source”:”PubMed Central”,”abstract”:”Cellular senescence acts as a potent mechanism of tumor suppression; however, its functional contribution to non-cancer pathologies has not been examined. Here we show that senescent cells accumulate in murine livers treated to produce fibrosis, a precursor pathology to cirrhosis. The senescent cells are derived primarily from activated hepatic stellate cells, which initially proliferate in response to liver damage and produce the extracellular matrix deposited in the fibrotic scar. In mice lacking key senescence regulators, stellate cells continue to proliferate, leading to excessive liver fibrosis. Furthermore, senescent activated stellate cells exhibit gene expression profile consistent with cell cycle exit, reduced secretion of extracellular matrix components, enhanced secretion of extracellular matrix degrading enzymes, and enhanced immune surveillance. Accordingly natural killer cells preferentially kill senescent activated stellate cells in vitro and in vivo, thereby facilitating the resolution of fibrosis. Therefore, the senescence program limits the fibrogenic response to acute tissue damage.”,”DOI”:”10.1016/j.cell.2008.06.049″,”ISSN”:”0092-8674″,”note”:”PMID: 18724938
PMCID: PMC3073300″,”journalAbbreviation”:”Cell”,”author”:{“family”:”Krizhanovsky”,”given”:”Valery”},{“family”:”Yon”,”given”:”Monica”},{“family”:”Dickins”,”given”:”Ross A.”},{“family”:”Hearn”,”given”:”Stephen”},{“family”:”Simon”,”given”:”Janelle”},{“family”:”Miething”,”given”:”Cornelius”},{“family”:”Yee”,”given”:”Herman”},{“family”:”Zender”,”given”:”Lars”},{“family”:”Lowe”,”given”:”Scott W.”},”issued”:{“date-parts”:”2008″,8,22}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 25.

4.4 HSCs inactivation

Figure 4: Schematic representation of the HSCs fate during liver regression ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”dLETsf2M”,”properties”:{“formattedCitation”:”26″,”plainCitation”:”26″,”noteIndex”:0},”citationItems”:{“id”:196,”uris”:”http://zotero.org/users/local/dX36zxw6/items/ZJJAMAPD”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/ZJJAMAPD”,”itemData”:{“id”:196,”type”:”article-journal”,”title”:”Resolution of Liver Fibrosis: Basic Mechanisms and Clinical Relevance”,”container-title”:”Seminars in Liver Disease”,”page”:”119-131″,”volume”:”35″,”issue”:”02″,”source”:”www.thieme-connect.com”,”abstract”:”;p;With evidence from a large number of animal models and clinical trials, it is now beyond debate that liver fibrosis and even cirrhosis are potentially reversible if the underlying cause can be successfully eliminated. However, in a significant proportion of patients cure of the underlying disease may not result in fibrosis regression or a significant reduction of the risk for hepatocellular carcinoma development. Understanding of the mechanistic pathways and regulatory factors that characterize matrix remodeling and architectural repair during fibrosis regression may provide therapeutic approaches to induce or accelerate regression as well as novel diagnostic tools. Recent seminal observations have determined that in resolving liver fibrosis a significant proportion of hepatic stellate cell-myofibroblasts (HSC-MFs) can revert to a near quiescent phenotype. Hepatic macrophages derived from inflammatory monocytes may contribute to fibrosis resolution through an in situ phenotypic switch mediated by phagocytosis. Emerging therapeutic approaches include deletion or inactivation of HSC-MFs, modulation of macrophage activity and autologous cell infusion therapies. Novel noninvasive diagnostic tests such as serum and imaging markers responsive to extracellular matrix degradation are being developed to evaluate the clinical efficacy of antifibrotic interventions.;/p;”,”DOI”:”10.1055/s-0035-1550057″,”ISSN”:”0272-8087, 1098-8971″,”shortTitle”:”Resolution of Liver Fibrosis”,”journalAbbreviation”:”Semin Liver Dis”,”language”:”en”,”author”:{“family”:”Ramachandran”,”given”:”Prakash”},{“family”:”Iredale”,”given”:”John P.”},{“family”:”Fallowfield”,”given”:”Jonathan A.”},”issued”:{“date-parts”:”2015″,5}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 26.

5. Effect of Statins on hepatic fibrosisStatins, also known as HMG-CoA reductase inhibitors, are potent cholesterol-lowering drug which inhibit the mevalonate pathway. The target of statins is the liver and more specifically the hepatocytes which are the only cells capable of transforming cholesterol to bile salts ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”g4Du1mx8″,”properties”:{“formattedCitation”:”27″,”plainCitation”:”27″,”noteIndex”:0},”citationItems”:{“id”:155,”uris”:”http://zotero.org/users/local/dX36zxw6/items/7UHERL4T”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/7UHERL4T”,”itemData”:{“id”:155,”type”:”article-journal”,”title”:”Pharmacodynamics and Pharmacokinetics of the HMG-CoA Reductase Inhibitors”,”container-title”:”Clinical Pharmacokinetics”,”page”:”403-425″,”volume”:”32″,”issue”:”5″,”source”:”Springer Link”,”abstract”:”SummaryHypercholesterolaemia plays a crucial role in the development of atherosclerotic diseases in general and coronary heart disease in particular. The risk of progression of the atherosclerotic process to coronary heart disease increases progressively with increasing levels of total serum cholesterol or low density lipoprotein (LDL) cholesterol at both the individual and the population level.The statins are reversible inhibitors of the microsomal enzyme HMG-CoA reductase, which converts HMG-CoAto mevalonate. This is an early rate-limiting step in cholesterol biosynthesis. Inhibition of HMG-CoA reductase by statins decreases intracellular cholesterol biosynthesis, which then leads to transcriptionally upregulated production of microsomal HMG-CoA reductase and cell surface LDL receptors. Subsequently, additional cholesterol is provided to the cell by de novo synthesis and by receptor-mediated uptake of LDL-cholesterol from the blood. This resets intracellular cholesterol homeostasis in extrahepatic tissues, but has little effect on the overall cholesterol balance.There are no simple methods to investigate the concentration-dependent inhibition of HMG-CoA reductase in human pharmacodynamic studies. The main clinical variable is plasma LDL-cholesterol, which takes 4 to 6 weeks to show a reduction after the start of statin treatment. Consequently, a dose-effect rather than a concentration-effect relationship is more appropriate to use in describing the pharmacodynamics. Fluvastatin, lovastatin, pravastatin and simvastatin have similar pharmacodynamic properties; all can reduce LDL-cholesterol by 20 to 35%, a reduction which has been shown to achieve decreases of 30 to 35% in major cardiovascular outcomes. Simvastatin has this effect at doses of about half those of the other 3 statins.The liver is the target organ for the statins, since it is the major site of cholesterol biosynthesis, lipoprotein production and LDLcatabolism. However, cholesterol biosynthesis in extrahepatic tissues is necessary for normal cell function. The adverse effects of HMG-reductase inhibitors during long term treatment may depend in part upon the degree to which they act in extrahepatic tissues. Therefore, pharmacokinetic factors such as hepatic extraction and systemic exposure to active compound(s) may be clinically important when comparing the statins.Different degrees of liver selectivity have been claimed for the HMG-CoA reductase inhibitors. However, the literature contains confusing data concerning the degree of liver versus tissue selectivity. Human pharmacokinetic data are poor and incomplete, especially for lovastatin and simvastatin, and it is clear that any conclusion on tissue selectivity is dependent upon the choice of experimental model. However, the drugs do differ in some important aspects concerning the degree of metabolism and the number of active and inactive metabolites. The rather extensive metabolism by different cytochrome P450 isoforms also makes it difficult to characterise these drugs regarding tissue selectivity unless all metabolites are well characterised.The effective elimination half-lives of the hydroxy acid forms of the 4 statins are 0.7 to 3.0 hours. Protein binding is similar (;90%) for fluvastatin, lovastatin and simvastatin, but it is only 50% for pravastatin. The best characterised statins from a clinical pharmacokinetic standpoint are fluvastatin and pravastatin. The major difference between these 2 compounds is the higher liver extraction of fluvastatin during the absorption phase compared with pravastatin (67 versus 45%, respectively, in the same dose range). Estimates of liver extraction in humans for lovastatin and simvastatin are poorly reported, which makes a direct comparison difficult.”,”DOI”:”10.2165/00003088-199732050-00005″,”ISSN”:”1179-1926″,”journalAbbreviation”:”Clin-Pharmacokinet”,”language”:”en”,”author”:{“family”:”Lennernäs”,”given”:”Hans”},{“family”:”Fager”,”given”:”Gunnar”},”issued”:{“date-parts”:”1997″,5,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 27.
The enzyme 3-hydroxy 3-methylglutaryl CoA (HMG-CoA) reductase, catalyze a rate-limiting step, the conversion of HMG-CoA to mevalonate, a central component of cholesterol biosynthesis. Blocking this pathway by statins has revolutionized the treatment of hypercholesterolemia ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”oTshVpF8″,”properties”:{“formattedCitation”:”28″,”plainCitation”:”28″,”noteIndex”:0},”citationItems”:{“id”:159,”uris”:”http://zotero.org/users/local/dX36zxw6/items/RHMFWPDJ”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/RHMFWPDJ”,”itemData”:{“id”:159,”type”:”article-journal”,”title”:”Statins in liver disease: a molehill, an iceberg, or neither?”,”container-title”:”Hepatology (Baltimore, Md.)”,”page”:”662-669″,”volume”:”48″,”issue”:”2″,”source”:”PubMed”,”abstract”:”A growing number of chronic liver disease patients, especially those with metabolic syndrome-associated nonalcoholic fatty liver disease or hepatitis C virus-associated dysmetabolic syndrome, will take statins to prevent cardiovascular disease. As a result, clinicians will weigh complex issues raised by the interaction of statins with liver metabolism in these disorders. In this article, we critically review data concerning statins and liver pathophysiology with an emphasis on nonalcoholic fatty liver disease and hepatitis C virus, while also touching on other chronic liver diseases. Basic research interests include statins’ mechanism of action and their effects on cholesterol-related cell signaling pathways and angiogenesis. From the clinical standpoint, many chronic liver diseases increase cardiovascular risk and would undeniably benefit from sustained statin use. The false alarms and security accompanying aminotransferase monitoring, however, are disturbing in light of the scarcity of data on statins’ long-term effects on liver histology. Although some actions of statins might eventually prove to be particularly useful in nonalcoholic steatohepatitis, hepatitis C virus, or hepatocellular carcinoma, others may prove harmful. The lack of definitive data makes a fully informed decision impossible. Research using histological endpoints is urgently needed to determine the indications and contraindications of this extraordinary class of agents in patients with chronic liver disease.”,”DOI”:”10.1002/hep.22402″,”ISSN”:”1527-3350″,”note”:”PMID: 18666246″,”shortTitle”:”Statins in liver disease”,”journalAbbreviation”:”Hepatology”,”language”:”eng”,”author”:{“family”:”Argo”,”given”:”Curtis K.”},{“family”:”Loria”,”given”:”Paola”},{“family”:”Caldwell”,”given”:”Stephen H.”},{“family”:”Lonardo”,”given”:”Amedeo”},”issued”:{“date-parts”:”2008″,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 28. In other way, statins do not only compete for the binding site of the substrate, but they also change the conformation of the enzyme thus, preventing the reach of a functional structure. However this binding is reversible ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”h1emAhu2″,”properties”:{“formattedCitation”:”29″,”plainCitation”:”29″,”noteIndex”:0},”citationItems”:{“id”:167,”uris”:”http://zotero.org/users/local/dX36zxw6/items/GT4U2KYM”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/GT4U2KYM”,”itemData”:{“id”:167,”type”:”article-journal”,”title”:”Statins: mechanism of action and effects”,”container-title”:”Journal of Cellular and Molecular Medicine”,”page”:”378-387″,”volume”:”5″,”issue”:”4″,”source”:”PubMed”,”abstract”:”The beneficial effects of statins are the result of their capacity to reduce cholesterol biosyntesis, mainly in the liver, where they are selectively distributed, as well as to the modulation of lipid metabolism, derived from their effect of inhibition upon HMG-CoA reductase. Statins have antiatherosclerotic effects, that positively correlate with the percent decrease in LDL cholesterol. In addition, they can exert antiatherosclerotic effects independently of their hypolipidemic action. Because the mevalonate metabolism generates a series of isoprenoids vital for different cellular functions, from cholesterol synthesis to the control of cell growth and differentiation, HMG-CoA reductase inhibition has beneficial pleiotropic effects. Consequently, statins reduce significantly the incidence of coronary events, both in primary and secondary prevention, being the most efficient hypolipidemic compounds that have reduced the rate of mortality in coronary patients. Independent of their hypolipidemic properties, statins interfere with events involved in bone formation and impede tumor cell growth.”,”ISSN”:”1582-1838″,”note”:”PMID: 12067471″,”shortTitle”:”Statins”,”journalAbbreviation”:”J. Cell. Mol. Med.”,”language”:”eng”,”author”:{“family”:”Stancu”,”given”:”C.”},{“family”:”Sima”,”given”:”A.”},”issued”:{“date-parts”:”2001″,12}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 29.

Reducing cholesterol level is not the only effect of statins, they are broadly known for their pleotropic effects on cardiovascular diseases and many more including,  anti-oxidative, immune modulatory, antibacterial, antithrombotic ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”eFNZD5I7″,”properties”:{“formattedCitation”:”30″,”plainCitation”:”30″,”noteIndex”:0},”citationItems”:{“id”:164,”uris”:”http://zotero.org/users/local/dX36zxw6/items/2DN52UNT”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/2DN52UNT”,”itemData”:{“id”:164,”type”:”article-journal”,”title”:”Statins in nonalcoholic fatty liver disease and steatohepatitis: updated review”,”container-title”:”Current Atherosclerosis Reports”,”page”:”305″,”volume”:”15″,”issue”:”3″,”source”:”PubMed”,”abstract”:”Non-alcoholic fatty liver disease (NAFLD) is a chronic liver disease that refers to the presence of hepatic steatosis without significant intake of alcohol. NAFLD is an asymptomatic disease that can progress to nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and hepatocellular carcinoma. The most common cause of mortality in patients with NAFLD or NASH is cardiovascular disease (CVD). Currently, the treatment of NAFLD focuses on gradual weight loss and life style modifications. However, multifactorial treatment of NAFLD or NASH risk factors may be needed to reduce the likelihood of these patients developing CVD. This review discusses the mechanisms that link hyperlipidemia and NAFLD. In addition, the review focuses on the safety and efficacy of statins in patients with NAFLD or NASH, and their effect on the extent of hepatic steatosis and fibrosis based on human studies.”,”DOI”:”10.1007/s11883-012-0305-5″,”ISSN”:”1534-6242″,”note”:”PMID: 23328905″,”shortTitle”:”Statins in nonalcoholic fatty liver disease and steatohepatitis”,”journalAbbreviation”:”Curr Atheroscler Rep”,”language”:”eng”,”author”:{“family”:”Nseir”,”given”:”William”},{“family”:”Mahamid”,”given”:”Mahmud”},”issued”:{“date-parts”:”2013″,3}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 30, anti-inflammatory, improvement or restoration of endothelial function as well as the stability of atherosclerotic plaques ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”t42YXcKJ”,”properties”:{“formattedCitation”:”31″,”plainCitation”:”31″,”noteIndex”:0},”citationItems”:{“id”:161,”uris”:”http://zotero.org/users/local/dX36zxw6/items/8GPHLEPV”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/8GPHLEPV”,”itemData”:{“id”:161,”type”:”article-journal”,”title”:”Pleiotropic effects of 3-hydroxy-3-methylglutaryl coenzyme a reductase inhibitors”,”container-title”:”Arteriosclerosis, Thrombosis, and Vascular Biology”,”page”:”1712-1719″,”volume”:”21″,”issue”:”11″,”source”:”PubMed”,”abstract”:”The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors or statins are potent inhibitors of cholesterol biosynthesis. Several large clinical trials have demonstrated the beneficial effects of statins in the primary and secondary prevention of coronary heart disease. However, the overall clinical benefits observed with statin therapy appear to be greater than what might be expected from changes in lipid profile alone, suggesting that the beneficial effects of statins may extend beyond their effects on serum cholesterol levels. Indeed, recent experimental and clinical evidence indicates that some of the cholesterol-independent or “pleiotropic” effects of statins involve improving or restoring endothelial function, enhancing the stability of atherosclerotic plaques, and decreasing oxidative stress and vascular inflammation. Many of these pleiotropic effects of statins are mediated by their ability to block the synthesis of important isoprenoid intermediates, which serve as lipid attachments for a variety of intracellular signaling molecules. In particular, the inhibition of small GTP-binding proteins, Rho, Ras, and Rac, whose proper membrane localization and function are dependent on isoprenylation, may play an important role in mediating the direct cellular effects of statins on the vascular wall.”,”ISSN”:”1524-4636″,”note”:”PMID: 11701455″,”journalAbbreviation”:”Arterioscler. Thromb. Vasc. Biol.”,”language”:”eng”,”author”:{“family”:”Takemoto”,”given”:”M.”},{“family”:”Liao”,”given”:”J. K.”},”issued”:{“date-parts”:”2001″,11}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 31. Furthermore, studies have shown that statins can control cell proliferation by reducing the DNA synthesis of normal and tumor cells in vitro, this is due to the reduction of mevalonate- derived metabolites synthesis such as isoprenoids ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”OqhtG4mT”,”properties”:{“formattedCitation”:”32″,”plainCitation”:”32″,”noteIndex”:0},”citationItems”:{“id”:170,”uris”:”http://zotero.org/users/local/dX36zxw6/items/2WKTZULH”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/2WKTZULH”,”itemData”:{“id”:170,”type”:”article-journal”,”title”:”Effect of simvastatin, an inhibitor of hydroxy-methylglutaryl coenzyme A reductase, on the growth of human Ito cells”,”container-title”:”Hepatology (Baltimore, Md.)”,”page”:”1589-1594″,”volume”:”20″,”issue”:”6″,”source”:”PubMed”,”abstract”:”During hepatic fibrogenesis, Ito cells proliferate, acquire a myofibroblastlike phenotype and synthesize increased amounts of extracellular matrix components. In this study, we have assessed the effects of simvastatin, an inhibitor of hydroxy-methylglutaryl-coenzyme A reductase, on the growth of human myofibroblastlike Ito cells. Cells were grown from explants of normal human liver and characterized by a positive staining for desmin and smooth muscle alpha-actin. Simvastatin (0.1 to 10 mumol/L) induced a marked dose-dependent decrease of 3Hthymidine incorporation in human Ito cells, whether stimulated by human serum or by purified growth factors. Simvastatin-induced inhibition of DNA synthesis was confirmed by nuclear autoradiography and was not explained by a cytotoxic effect. The growth inhibitory effect of simvastatin was specifically due to inhibition of hydroxy-methylglutaryl-coenzyme A reductase because it was overcome by addition of mevalonic acid, the product of the enzymatic reaction. The reduction in 3Hthymidine incorporation was not affected by supplementation of culture medium with purified cholesterol-low-density lipoprotein or isopentenyl adenine. It was partially reversed by addition of farnesol. These results show that simvastatin decreases the growth of human Ito cells, independently of its effect on cholesterol synthesis. This decrease may be due in part either to reduced farnesylation of proteins involved in growth factor signaling pathway or to inhibition of N-linked protein glycosylation. Whether this effect exists in vivo and could thus lead to a parallel decrease of fibrosis deposition within the liver requires further study.”,”ISSN”:”0270-9139″,”note”:”PMID: 7982659″,”journalAbbreviation”:”Hepatology”,”language”:”eng”,”author”:{“family”:”Mallat”,”given”:”A.”},{“family”:”Preaux”,”given”:”A. M.”},{“family”:”Blazejewski”,”given”:”S.”},{“family”:”Dhumeaux”,”given”:”D.”},{“family”:”Rosenbaum”,”given”:”J.”},{“family”:”Mavier”,”given”:”P.”},”issued”:{“date-parts”:”1994″,12}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 32. Isoprenoids are essential for the prenylation of proteins that facilitates their anchoring in the cell membrane, such as small GTPases families of Ras and Rho. Hence, intracellular signaling pathways are modified by statins ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”zLocVjGJ”,”properties”:{“formattedCitation”:”33″,”plainCitation”:”33″,”noteIndex”:0},”citationItems”:{“id”:173,”uris”:”http://zotero.org/users/local/dX36zxw6/items/U7ES9PNK”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/U7ES9PNK”,”itemData”:{“id”:173,”type”:”article-journal”,”title”:”Statins improve NASH via inhibition of RhoA and Ras”,”container-title”:”American Journal of Physiology. Gastrointestinal and Liver Physiology”,”page”:”G724-G733″,”volume”:”311″,”issue”:”4″,”source”:”PubMed”,”abstract”:”Nonalcoholic steatohepatitis (NASH), especially as part of the metabolic syndrome (MS), is an increasing burden in Western countries. Statins are already used in MS and seem to be beneficial in liver diseases. The aim of this study was to investigate the molecular mechanisms underlying pleiotropic effects on small GTPases of statins in NASH. NASH within MS was induced in 12-wk-old apoE-/- mice after 7 wk of Western diet (NASH mice). Small GTPases were inhibited by activated simvastatin (SMV), NSC23766 (NSC), or Clostridium sordellii lethal toxin (LT) by using subcutaneous osmotic minipumps. Hepatic steatosis, inflammation, and fibrosis were assessed by histology, Western blot, and RT-PCR measurements of cholesterol and hydroxyproline content. SMV treatment significantly decreased hepatic inflammation and fibrosis, but had no significant effect on steatosis and hepatic cholesterol content in NASH. SMV blunted fibrosis due to inhibition of both RhoA/Rho kinase and Ras/ERK pathways. Interestingly, inhibition of RAC1 and Ras (by LT) failed to decrease fibrosis to the same extent. Inhibition of RAC1 (by NSC) showed no significant effect at all. Inhibition of RhoA and Ras downstream signaling by statins is responsible for the beneficial hepatic effects in NASH.”,”DOI”:”10.1152/ajpgi.00063.2016″,”ISSN”:”1522-1547″,”note”:”PMID: 27634010″,”journalAbbreviation”:”Am. J. Physiol. Gastrointest. Liver Physiol.”,”language”:”eng”,”author”:{“family”:”Schierwagen”,”given”:”Robert”},{“family”:”Maybüchen”,”given”:”Lara”},{“family”:”Hittatiya”,”given”:”Kanishka”},{“family”:”Klein”,”given”:”Sabine”},{“family”:”Uschner”,”given”:”Frank E.”},{“family”:”Braga”,”given”:”Tarcio T.”},{“family”:”Franklin”,”given”:”Bernardo S.”},{“family”:”Nickenig”,”given”:”Georg”},{“family”:”Strassburg”,”given”:”Christian P.”},{“family”:”Plat”,”given”:”Jogchum”},{“family”:”Sauerbruch”,”given”:”Tilman”},{“family”:”Latz”,”given”:”Eicke”},{“family”:”Lütjohann”,”given”:”Dieter”},{“family”:”Zimmer”,”given”:”Sebastian”},{“family”:”Trebicka”,”given”:”Jonel”},”issued”:{“date-parts”:”2016″,10,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 33.

Regarding the effect of statins on hepatic fibrosis, many studies have demonstrated that this drug inhibits the activation and proliferation of HSCs as well as induces their apoptosis. Hence, decreases the production of ECM. Therefore, Statin can be an efficient anti?brotic agent in liver ?brosis ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”Zu9OqhIc”,”properties”:{“formattedCitation”:”34″,”plainCitation”:”34″,”noteIndex”:0},”citationItems”:{“id”:185,”uris”:”http://zotero.org/users/local/dX36zxw6/items/X3UUQ6UA”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/X3UUQ6UA”,”itemData”:{“id”:185,”type”:”article-journal”,”title”:”Synergistic antifibrotic efficacy of statin and protein kinase C inhibitor in hepatic fibrosis”,”container-title”:”American Journal of Physiology. Gastrointestinal and Liver Physiology”,”page”:”G126-132″,”volume”:”298″,”issue”:”1″,”source”:”PubMed”,”abstract”:”Statin has antifibrotic efficacy in human fibrosing diseases, such as pulmonary and renal fibrosis, and is therefore implicated in hepatic fibrosis. However, statin can also activate protein kinase C (PKC), which augments hepatic fibrogenesis and is thereby likely to reduce the antifibrotic efficacy of statin. This study was designed to explore the hypothesis that simultaneous treatment with statin and PKC inhibitor may synergistically enhance antifibrotic efficacy in hepatic fibrosis. Hepatic fibrosis models were established in BALB/c mice by intraperitoneal injection of carbon tetrachloride or thioacetamide for 6 wk. Pravastatin and enzastaurin (PKC inhibitor) were administered by gavage for 5 wk. Cellular apoptosis was explored using 4′,6-diamidino-2-phenylindole or terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate biotin nick end-labeling (TUNEL) staining and immunoblot analysis. Hepatic fibrosis and hepatic stellate cell (HSC) activation were assessed by morphometric analysis of histological findings and immunohistochemistry for alpha-smooth muscle actin. In vitro, the addition of PKC inhibitor significantly increased statin-induced LX-2 cell apoptosis by enhancing the activation of mitochondrial apoptotic signals. TUNEL-positive HSCs were significantly increased in mice treated with statin + PKC inhibitor compared with those in control or single compound-treated mice. The percentage of area occupied by activated HSCs and the extent of collagen deposition were significantly decreased in mice treated with statin + PKC inhibitor compared with those in control or statin-treated mice. In conclusion, simultaneous treatment with statin and PKC inhibitor synergistically enhanced the antifibrotic efficacy in both in vitro and in vivo models of hepatic fibrosis and may therefore have therapeutic implication for reducing hepatic fibrosis.”,”DOI”:”10.1152/ajpgi.00299.2009″,”ISSN”:”1522-1547″,”note”:”PMID: 19910526″,”journalAbbreviation”:”Am. J. Physiol. Gastrointest. Liver Physiol.”,”language”:”eng”,”author”:{“family”:”Yang”,”given”:”Jong In”},{“family”:”Yoon”,”given”:”Jung-Hwan”},{“family”:”Bang”,”given”:”Yung-Jue”},{“family”:”Lee”,”given”:”Sung-Hee”},{“family”:”Lee”,”given”:”Soo-Mi”},{“family”:”Byun”,”given”:”Hee Jin”},{“family”:”Myung”,”given”:”Sun-Jung”},{“family”:”Kim”,”given”:”Won”},{“family”:”Lee”,”given”:”Hyo-Suk”},”issued”:{“date-parts”:”2010″,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 34. For example a study on cirrhotic rats showed that atorvastatin inhibits HSCs activity and reduction of collagen deposition as well as decreases portal hypertension by inhibiting the RhoA/Rho kinase pathway ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”QXIBhfjh”,”properties”:{“formattedCitation”:”33″,”plainCitation”:”33″,”noteIndex”:0},”citationItems”:{“id”:173,”uris”:”http://zotero.org/users/local/dX36zxw6/items/U7ES9PNK”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/U7ES9PNK”,”itemData”:{“id”:173,”type”:”article-journal”,”title”:”Statins improve NASH via inhibition of RhoA and Ras”,”container-title”:”American Journal of Physiology. Gastrointestinal and Liver Physiology”,”page”:”G724-G733″,”volume”:”311″,”issue”:”4″,”source”:”PubMed”,”abstract”:”Nonalcoholic steatohepatitis (NASH), especially as part of the metabolic syndrome (MS), is an increasing burden in Western countries. Statins are already used in MS and seem to be beneficial in liver diseases. The aim of this study was to investigate the molecular mechanisms underlying pleiotropic effects on small GTPases of statins in NASH. NASH within MS was induced in 12-wk-old apoE-/- mice after 7 wk of Western diet (NASH mice). Small GTPases were inhibited by activated simvastatin (SMV), NSC23766 (NSC), or Clostridium sordellii lethal toxin (LT) by using subcutaneous osmotic minipumps. Hepatic steatosis, inflammation, and fibrosis were assessed by histology, Western blot, and RT-PCR measurements of cholesterol and hydroxyproline content. SMV treatment significantly decreased hepatic inflammation and fibrosis, but had no significant effect on steatosis and hepatic cholesterol content in NASH. SMV blunted fibrosis due to inhibition of both RhoA/Rho kinase and Ras/ERK pathways. Interestingly, inhibition of RAC1 and Ras (by LT) failed to decrease fibrosis to the same extent. Inhibition of RAC1 (by NSC) showed no significant effect at all. Inhibition of RhoA and Ras downstream signaling by statins is responsible for the beneficial hepatic effects in NASH.”,”DOI”:”10.1152/ajpgi.00063.2016″,”ISSN”:”1522-1547″,”note”:”PMID: 27634010″,”journalAbbreviation”:”Am. J. Physiol. Gastrointest. Liver Physiol.”,”language”:”eng”,”author”:{“family”:”Schierwagen”,”given”:”Robert”},{“family”:”Maybüchen”,”given”:”Lara”},{“family”:”Hittatiya”,”given”:”Kanishka”},{“family”:”Klein”,”given”:”Sabine”},{“family”:”Uschner”,”given”:”Frank E.”},{“family”:”Braga”,”given”:”Tarcio T.”},{“family”:”Franklin”,”given”:”Bernardo S.”},{“family”:”Nickenig”,”given”:”Georg”},{“family”:”Strassburg”,”given”:”Christian P.”},{“family”:”Plat”,”given”:”Jogchum”},{“family”:”Sauerbruch”,”given”:”Tilman”},{“family”:”Latz”,”given”:”Eicke”},{“family”:”Lütjohann”,”given”:”Dieter”},{“family”:”Zimmer”,”given”:”Sebastian”},{“family”:”Trebicka”,”given”:”Jonel”},”issued”:{“date-parts”:”2016″,10,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 33. In fact, geranylgeranyl pyrophosphate reduction alters RhoA activity and its downstream effector Rho-kinase in activated hepatic stellate cells. Furthermore, portal pressure reduction and intrahepatic resistance in vivo were proven to be mediated by the upregulation of endothelial NO synthase (eNOS). Thus enhancing NO synthesis ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”oohaB6np”,”properties”:{“formattedCitation”:”35″,”plainCitation”:”35″,”noteIndex”:0},”citationItems”:{“id”:”7RJD1lbr/J5j0EtEK”,”uris”:”http://zotero.org/users/local/dX36zxw6/items/AZ9536SH”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/AZ9536SH”,”itemData”:{“id”:175,”type”:”article-journal”,”title”:”Statins, Rho GTPases and KLF2: new mechanistic insight into liver fibrosis and portal hypertension”,”container-title”:”Gut”,”page”:”1349-1350″,”volume”:”64″,”issue”:”9″,”source”:”PubMed”,”DOI”:”10.1136/gutjnl-2014-308800″,”ISSN”:”1468-3288″,”note”:”PMID: 25596180″,”shortTitle”:”Statins, Rho GTPases and KLF2″,”journalAbbreviation”:”Gut”,”language”:”eng”,”author”:{“family”:”Trebicka”,”given”:”Jonel”},{“family”:”Schierwagen”,”given”:”Robert”},”issued”:{“date-parts”:”2015″,9}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 35. Indeed, NO is normally produced by LSECs mediated by eNOS and applies exerts paracrine effects on HSCs. However, NO produced by inducible NO synthase (iNOS), contributes to tissue damage in case of inflammation. In vivo study confirmed that simvastatin ameliorate hepatic fibrosis by mediating the expression eNOS of and inhibiting iNOS expression ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”TVr4Tnmp”,”properties”:{“formattedCitation”:”36″,”plainCitation”:”36″,”noteIndex”:0},”citationItems”:{“id”:190,”uris”:”http://zotero.org/users/local/dX36zxw6/items/UC3ZEA42″,”uri”:”http://zotero.org/users/local/dX36zxw6/items/UC3ZEA42″,”itemData”:{“id”:190,”type”:”article-journal”,”title”:”Simvastatin Ameliorates Liver Fibrosis via Mediating Nitric Oxide Synthase in Rats with Non-Alcoholic Steatohepatitis-Related Liver Fibrosis”,”container-title”:”PLOS ONE”,”page”:”e76538″,”volume”:”8″,”issue”:”10″,”source”:”PLoS Journals”,”abstract”:”BackgroundSimvastatin exerts pleiotropic effects on cardiovascular system. However, its effect on non-alcoholic fatty liver disease, especially the liver fibrosis, remains obscure. We aimed to clarify the relationship between simvastatin and liver fibrosis both in vivo and in vitro. MethodsA High-fat diet was given to establish rat models with non-alcoholic steatohepatitis (NASH)-related liver fibrosis and simvastatin (4mg·kg-1·d-1) was administrated intragastrically until hepatic histological findings confirmed the appearance of fibrosis. Human hepatic stellate cell (HSC) line lx-2 cells were cultured in an adipogenic differentiating mixture (ADM) and then were treated with transforming growth factor?1 (TGF-?1), served as a positive control, simvastatin, TGF-?1 plus simvastatin, N?-nitro-L-arginine methyl ester hydrochloride (L-NAME, a inhibitor of nitric oxide synthase), and L-NAME plus simvastatin, respectively. The expressions of endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS), and Collagen ? as well as cellular ?-smooth muscle actin (?-SMA) were measured by real-time reverse transcriptase-polymerase chain reaction (qRT-PCR) and Western blot in liver tissue and HSC. ResultsWith the progress of NASH-related fibrosis, hepatic mRNA and protein expressions of iNOS, ?-SMA, and Collagen ? were increased while those of eNOS were decreased. Compared with model rats in 24th week group, rats in simvastatin group had less expressions of iNOS, ?-SMA, and Collagen ? and more expressions of eNOS. In vitro, LX-2 cells acquired quiescent phenotype when cultured in ADM, and TGF-?1 could activate the quiescent HSC. Simvastatin inhibited LX-2 cells activation due to TGF-?1 or L-NAME by increasing the expression of eNOS and decreasing the expression of iNOS. ConclusionsSimvastatin improves the prognosis of NASH-related fibrosis by increasing the expression of eNOS, decreasing the expression of iNOS, and inhibiting the activation of HSC.”,”DOI”:”10.1371/journal.pone.0076538″,”ISSN”:”1932-6203″,”journalAbbreviation”:”PLOS ONE”,”language”:”en”,”author”:{“family”:”Wang”,”given”:”Wei”},{“family”:”Zhao”,”given”:”Caiyan”},{“family”:”Zhou”,”given”:”Junying”},{“family”:”Zhen”,”given”:”Zhen”},{“family”:”Wang”,”given”:”Yadong”},{“family”:”Shen”,”given”:”Chuan”},”issued”:{“date-parts”:”2013″,10,2}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 36. Other in vivo and in vitro studies demonstrated that decreasing and increasing level of collagen production as well as activation and contraction of HSCs is dependent on the nuclear receptor KLF2 a downstream effector of RhoA ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”iOX3p5HL”,”properties”:{“formattedCitation”:”35″,”plainCitation”:”35″,”noteIndex”:0},”citationItems”:{“id”:”7RJD1lbr/J5j0EtEK”,”uris”:”http://zotero.org/users/local/dX36zxw6/items/AZ9536SH”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/AZ9536SH”,”itemData”:{“id”:175,”type”:”article-journal”,”title”:”Statins, Rho GTPases and KLF2: new mechanistic insight into liver fibrosis and portal hypertension”,”container-title”:”Gut”,”page”:”1349-1350″,”volume”:”64″,”issue”:”9″,”source”:”PubMed”,”DOI”:”10.1136/gutjnl-2014-308800″,”ISSN”:”1468-3288″,”note”:”PMID: 25596180″,”shortTitle”:”Statins, Rho GTPases and KLF2″,”journalAbbreviation”:”Gut”,”language”:”eng”,”author”:{“family”:”Trebicka”,”given”:”Jonel”},{“family”:”Schierwagen”,”given”:”Robert”},”issued”:{“date-parts”:”2015″,9}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 35. Statins play a major role in up-regulating KLF2; this will not only improve the phenotype of HSCs but also inhibit the paracrine interaction with LSECs and finally decrease fibrosis levels ( Figure 5) ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”uZovLtGf”,”properties”:{“formattedCitation”:”37″,”plainCitation”:”37″,”noteIndex”:0},”citationItems”:{“id”:192,”uris”:”http://zotero.org/users/local/dX36zxw6/items/AWDHIYW9″,”uri”:”http://zotero.org/users/local/dX36zxw6/items/AWDHIYW9″,”itemData”:{“id”:192,”type”:”article-journal”,”title”:”Statins in cirrhosis-Ready for prime time”,”container-title”:”Hepatology (Baltimore, Md.)”,”page”:”697-699″,”volume”:”66″,”issue”:”3″,”source”:”PubMed”,”DOI”:”10.1002/hep.29277″,”ISSN”:”1527-3350″,”note”:”PMID: 28543643″,”journalAbbreviation”:”Hepatology”,”language”:”eng”,”author”:{“family”:”Tsochatzis”,”given”:”Emmanuel A.”},{“family”:”Bosch”,”given”:”Jaime”},”issued”:{“date-parts”:”2017″}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 37.

Figure 5:  schematic summary of the signaling pathway by which statins decrease portal pressure and reduce hepatic fibrosis ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”1TrzO21K”,”properties”:{“formattedCitation”:”35″,”plainCitation”:”35″,”noteIndex”:0},”citationItems”:{“id”:”7RJD1lbr/J5j0EtEK”,”uris”:”http://zotero.org/users/local/dX36zxw6/items/AZ9536SH”,”uri”:”http://zotero.org/users/local/dX36zxw6/items/AZ9536SH”,”itemData”:{“id”:175,”type”:”article-journal”,”title”:”Statins, Rho GTPases and KLF2: new mechanistic insight into liver fibrosis and portal hypertension”,”container-title”:”Gut”,”page”:”1349-1350″,”volume”:”64″,”issue”:”9″,”source”:”PubMed”,”DOI”:”10.1136/gutjnl-2014-308800″,”ISSN”:”1468-3288″,”note”:”PMID: 25596180″,”shortTitle”:”Statins, Rho GTPases and KLF2″,”journalAbbreviation”:”Gut”,”language”:”eng”,”author”:{“family”:”Trebicka”,”given”:”Jonel”},{“family”:”Schierwagen”,”given”:”Robert”},”issued”:{“date-parts”:”2015″,9}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 35.Aim of the Project
Chapter II: Materials and methods1. Animals
Eleven-week-old male C57BL/6J mice weighing 20-30 g were purchased from *** Laboratories and housed in a pathogen-free environment. All experiments were performed in accordance with the Institutional Animal Care and Use Committee (IACUC) of the American University of Beirut (AUB) following the ‘Guide for the care and use of laboratory animals’ and the “US Government Principles for the Utilization and Care of Vertebrate Animals used in Testing, Research and Training”.
2. Experimental Design2.1 Carbon tetrachloride- (CCL4-) induced liver injuryEach mouse was given two intraperitoneal injections of 0.6ml/kg CCl4 (**) mixed with mineral oil (**) at the ratio of 1:10, for 6 consecutive weeks. Mice were sacrificed at one and four days after the last injection. The control group was injected with mineral oil (Figure 6-A). REF _Ref523214811 h * MERGEFORMAT
2.2 Antifibrotic effect of Pitavastatin on liver fibrosis.Liver fibrosis model was generated as mentioned before. Mice were injected by CCl4. Starting from the third week, the mice were divided into two groups and beside CCl4 injection, they were injected daily by either 10mg/kg of Pitavastatin (**) or by the same volume of DMSO (***) as a vehicle for 13 or 15 days until their sacrifice at 1 or 3 days after the last injection of CCl4 (Figure 6–B).

2.3 Regression effect of Pitavastatin on liver fibrosisAs mentioned previously, fibrosis induction was done by injecting for 6 weeks in a row, 0.6 ml/kg CCl4. After the last injection of CCl4, the mice were divided into two groups and daily treated by either 10mg/kg of Pitavastatin or DMSO until their sacrifice at 1, 2, 3 or 4 days post treatment (Figure 6-C).

weeks1264530.6 ml/kg CCl441weeks1264530.6 ml/kg CCl431weeks1264530.6 ml/kg CCl41234ACB: Last injection of CCl4 : Injection of 10 mg/kg Pitavastatin: Sacrifice days
Figure 6: Schematic representation of the liver fibrosis model in male C57BL/6J mice.(A) Liver fibrosis was developed by injecting 0.6 ml/kg CCl4 intraperitonealy twice a week for 6 weeks. sacrifice occurred at day 1 and 4 post-treatment. (B) Antifibrotic model was induced after the third week of CCl4 administration by daily injection of 10mg/kg Pitavastatin. Mice were sacrificed after day 1 and 3 post-treatment (C) Liver regression was induced by injecting 10mg/kg pitavastatin after 6 weeks injection of CCl4 followed by harvest at serial time points after the final injection.

3. Pico Sirius Red staining.Liver fragments were fixed in 10% buffered formaldehyde for at least ***days. Four micrometers sections were cut and stained with Pico Sirius red (reference).

4. Immunohistochemistry staining of hepatic ?SMA.Liver tissue was deparaffined into 100% xylene followed by a hydration with 100%, 90% and 80% ethanol for 5min each. Sections were rinsed by tape water for 10 minutes and were hydrated in 1x TBS buffer for 30 min at RT. In order to break down the molecular cross links formed by formalin fixation, sections were heated twice in a boiling antigen retrieval buffer in the microwaver for 5 min. After cooling down, the slides were washed by TBS pH=7.6 for 10 minutes then blocked in a normal serum (4% serum, 0.1% TX100) (Serotec Biorad cat #) for 30 min at RT. 3% H2O2 was then used to Block endogenous peroxidase activity. the endogenous unspecific avidin biotin was blocked by Avidin-Biotin blocking kit (Vector Lab, SP-2001) according to the instructions received from the vendor. The sections were then washed twice in 1x TBS. Next, the slides were incubated working solution of MOM mouse Ig blocking reagent (from M.O.M kit (Vector, BMK-2202, 4°C)) for 1h , washed twice by 1x TBS pH=7.6 for 2 min and then incubated by working solution of MOM diluents (from M.O.M kit (Vector, BMK-2202, 4°C)) for 5 min at RT. Mouse monoclonal anti ?SMA antibody diluted 1:10000 was used as primary antibody (Sigma, A2547, clone 1A4). The sections were incubated overnight. Next day, slides were incubated by secondary antibody; MOM biotinylated goat-anti-mouse antibody (from M.O.M kit) diluted 1:500 for 30 min. after several washes tissues were incubated first with working solution of Vectastain ABC reagent (**) for 30 min, then with DAB solution (Dako) and finally counterstained with hematoxyline (Novacastra Leica Biosystem Ref RE7107 Lot 6055893) and mounted by Shandon Immu-mount (Thermo scientific, Ref 9990412). Negative control was performed using MOM diliuent solution instead of the primary antibody which demonstrated no reaction.

5. ALT and AST detectionBlood samples were collected on the day of sacrifice.  The samples were centrifuged at 2 xg for 15 minutes at 4 ºC. Serum ALT and AST levels were detected using *** kit (***) by ***
6. RNA ExtractionRNA was isolated from frozen liver tissue. The tissue were disrupted and homogenized with 1 ml QIAzol Lysis Reagent (QIAGEN,79306) and 5mm stainless steel beads (QIAGEN, Ref 69989) using the TissueLyser Qiagen (QIAGEN, II) adjusted to a frequency of 20 Hz for 2 minutes twice. Following homogenization, the lysates were transferred to 1.5 ml eppendorf tubes. 200 ?l chloroform was added to each sample, and shacked vigorously for 15 seconds by inversion. Mixtures were incubated at room temperature for three minutes before being centrifuged at 12,000xg for 15 minutes at 4°C.

After centrifugation, the sample separates into 3 phases: an upper, colorless, aqueous phase containing RNA; a white interphase; and a lower, red, organic phase. The upper aqueous phase of RNA was collected and transferred to the gDNA Removal Column and centrifuged for 30s at 11000 xg. After removing genomic DNA, 100?l of binding solution were added to 350?l lysate, mixed well, transferred to the RNA plus column and centrifuged for 15s at 11000xg. Now the RNA was binding the silica gel membrane, three washes were done in order to removes any remaining impurities from the membrane. First one by adding 200 µl WB1 wash buffer, the second with 600 µl WB2 and the third with 250 µl WB2. Samples were centrifuged after each wash as mentioned before. Finally, in order to eluate the RNA in a new eppendorf tube, 30 µl RNase-free H2O were added to the column then centrifuged for 1 min at 11000 xg. This step was repeated using the remainder of the sample. Total RNA was extracted using the RNeasy Kit MN Nucleospin RNA plus (***, cat # 740984.50).

The resulting RNA was quantified using Nanodrop (Thermo Fisher Scientific) by measuring the absorbance at 260 nm (A260). The ratio of the readings at 260 nm and 280 nm (A260/A280) provides an estimate of the purity of RNA regarding contaminants that absorb in the UV, such as protein. Pure RNA has an A260/A280 ratio of 1.8 to 2.0.

7. Reverse transcription-PCRReverse transcription was performed on 1µg of total RNA in a final 20 µl volume using the *** kit () this included creating a negative RT control without reverse transcriptase. The cycle begins at 25°C for 10 min, 37°C for 2 hours, 85°C for 5 min, and ends at 4°C, using the RT-PCR machine (Bio-Rad Laboratories, California, USA). The cDNA samples were stored at -20°C.

8. Real-Time PCRReal-time PCR reactions were performed using CFX384 system (Bio-Rad Laboratories, California, USA) with iTaq™ Universal SYBR® Green supermix (Bio-Rad Laboratories, California, USA). The plate was run for 56 cycles. The first cycle was run at 94°C for 15 min followed by 55 cycles each at 94°C for 15 seconds, 56°C for 20 seconds, and finally 72°C for 30 seconds. Melting curves were evaluated to check for primer specificity for the PCR product and the results were quantified and analyzed using the Delta-Delta CT method. The primer sequences are listed in Table 1.The housekeeping gene 18S rRNA was used for normalization.

Table 1: List of primer sequences used for RT-PCR analysis.Target genes Forward primer Reverse primer
18S 5′-AAC TTT CGA TGG TAG TCG CCG T-3′ 5′-TCC TTG GAT GTG GTA GCC GTT T-3′
TGF-? 5′-TGC GCT TGC AGA GAT TAA AA-3′ 5′-CTG CCG TAC AAC TCC AGT GA-3′
ACATA2 5′-AAC AGC ATC ATG AAG TGT GAT ATT GAC-3′ 5′-GCT GAT CCA CAT CTG CTG GAA GG-3′
CTGF 5′-AAT GTC AGT GCG CAG CCG AAG CA-3′ 5′-AGG GGT CAC GCT CCG TAC ACA G-3′
MMP2 5′-AGA TGC AGA AGT TCT TTG GGC TGC-3′ 5′-AGT TGT AGT TGG CCA CAT CTG GGT-3′
MMP9 5′-ACC ACA GCC AAC TAT GAC CAG GAT-3′ 5′-AAG AGT ACT GCT TGC CCA CCA AGA-3′
MMP13 5′- 5′-
TIMP-1 5′-TGG ATA TGC CCA CAA GTC CCA GAA-3′ 5′-TCC GTC CAC AAA CAG TGA GTG TCA-3′
PDGFR? 5′- 5′-
9. Statistical analysisAnimals were randomly selected for the control and treatment group. All results were expressed as the means ± SEM. Differences between groups were analyzed by the Mann-Whitney test, using “GraphPad Prism” software. The p values for p<0.05 and p<0.01, (*, ** respectively) deemed to be indicative of significance.

Chapter III: Results1. Experimental liver fibrosis model1.1 Serum ALT AST
Chapter IV: Discussion and Conclusion
Chapter V: Future perspectivess
References ADDIN ZOTERO_BIBL {“uncited”:,”omitted”:,”custom”:} CSL_BIBLIOGRAPHY 1S. N. Bhatia, G. H. Underhill, K. S. Zaret, and I. J. Fox, “Cell and Tissue Engineering for Liver Disease,” Sci. Transl. Med., vol. 6, no. 245, p. 245sr2, Jul. 2014.

2A. Altamirano-Barrera, B. Barranco-Fragoso, and N. Méndez-Sánchez, “Management strategies for liver fibrosis,” Ann. Hepatol., vol. 16, no. 1, pp. 48–56, Feb. 2017.3A. Mallat and S. Lotersztajn, “Cellular mechanisms of tissue fibrosis. 5. Novel insights into liver fibrosis,” Am. J. Physiol. Cell Physiol., vol. 305, no. 8, pp. C789-799, Oct. 2013.4T. R. Cox and J. T. Erler, “Remodeling and homeostasis of the extracellular matrix: implications for fibrotic diseases and cancer,” Dis. Model. Mech., vol. 4, no. 2, pp. 165–178, Mar. 2011.

5M. Gordillo, T. Evans, and V. Gouon-Evans, “Orchestrating liver development,” Dev. Camb. Engl., vol. 142, no. 12, pp. 2094–2108, Jun. 2015.

6E. Trefts, M. Gannon, and D. H. Wasserman, “The liver,” Curr. Biol., vol. 27, no. 21, pp. R1147–R1151, Nov. 2017.

7C. Ding et al., “A Cell-type-resolved Liver Proteome,” Mol. Cell. Proteomics MCP, vol. 15, no. 10, pp. 3190–3202, Oct. 2016.

8R. J. Washabau and M. J. Day, Eds., “Chapter?61 – Liver,” in Canine and Feline Gastroenterology, Saint Louis: W.B. Saunders, 2013, pp. 849–957.

9N. Fausto and J. S. Campbell, “The role of hepatocytes and oval cells in liver regeneration and repopulation,” Mech. Dev., vol. 120, no. 1, pp. 117–130, Jan. 2003.10O. Krenkel and F. Tacke, “Liver macrophages in tissue homeostasis and disease,” Nat. Rev. Immunol., vol. 17, no. 5, pp. 306–321, May 2017.11A. Ahmad and R. Ahmad, “Understanding the Mechanism of Hepatic Fibrosis and Potential Therapeutic Approaches,” Saudi J. Gastroenterol. Off. J. Saudi Gastroenterol. Assoc., vol. 18, no. 3, pp. 155–167, 2012.12J. Poisson et al., “Liver sinusoidal endothelial cells: Physiology and role in liver diseases,” J. Hepatol., vol. 66, no. 1, pp. 212–227, Jan. 2017.

13Y. Ni et al., “Pathological process of liver sinusoidal endothelial cells in liver diseases,” World J. Gastroenterol., vol. 23, no. 43, pp. 7666–7677, Nov. 2017.

14S. Shetty, P. F. Lalor, and D. H. Adams, “Liver sinusoidal endothelial cells — gatekeepers of hepatic immunity,” Nat. Rev. Gastroenterol. Hepatol., p. 1, May 2018.

15S. Lemoinne, A. Cadoret, H. El Mourabit, D. Thabut, and C. Housset, “Origins and functions of liver myofibroblasts,” Biochim. Biophys. Acta BBA – Mol. Basis Dis., vol. 1832, no. 7, pp. 948–954, Jul. 2013.

16J. IJzer et al., “Morphological characterisation of portal myofibroblasts and hepatic stellate cells in the normal dog liver,” Comp. Hepatol., vol. 5, no. 1, p. 7, Nov. 2006.17T. Tsuchida and S. L. Friedman, “Mechanisms of hepatic stellate cell activation,” Nat. Rev. Gastroenterol. Hepatol., vol. 14, no. 7, pp. 397–411, Jul. 2017.

18N. Bosselut et al., “Distinct proteomic features of two fibrogenic liver cell populations: hepatic stellate cells and portal myofibroblasts,” Proteomics, vol. 10, no. 5, pp. 1017–1028, Mar. 2010.

19J. P. Iredale, “Models of liver fibrosis: exploring the dynamic nature of inflammation and repair in a solid organ,” J. Clin. Invest., vol. 117, no. 3, pp. 539–548, Mar. 2007.

20R. Weiskirchen and F. Tacke, “Liver fibrosis: Which mechanisms matter?,” Clin. Liver Dis., vol. 8, no. 4, pp. 94–99, Oct. 2016.

21A. Pellicoro, P. Ramachandran, J. P. Iredale, and J. A. Fallowfield, “Liver fibrosis and repair: immune regulation of wound healing in a solid organ,” Nat. Rev. Immunol., vol. 14, no. 3, pp. 181–194, Mar. 2014.

22L. Campana and J. P. Iredale, “Regression of Liver Fibrosis,” Semin. Liver Dis., vol. 37, no. 1, pp. 1–10, 2017.23F. Tacke and C. Trautwein, “Mechanisms of liver fibrosis resolution,” J. Hepatol., vol. 63, no. 4, pp. 1038–1039, Oct. 2015.24M. Sun and T. Kisseleva, “Reversibility of Liver Fibrosis,” Clin. Res. Hepatol. Gastroenterol., vol. 39, no. 0 1, pp. S60–S63, Sep. 2015.

25V. Krizhanovsky et al., “Senescence of activated stellate cells limits liver fibrosis,” Cell, vol. 134, no. 4, pp. 657–667, Aug. 2008.

26P. Ramachandran, J. P. Iredale, and J. A. Fallowfield, “Resolution of Liver Fibrosis: Basic Mechanisms and Clinical Relevance,” Semin. Liver Dis., vol. 35, no. 02, pp. 119–131, May 2015.

27H. Lennernäs and G. Fager, “Pharmacodynamics and Pharmacokinetics of the HMG-CoA Reductase Inhibitors,” Clin. Pharmacokinet., vol. 32, no. 5, pp. 403–425, May 1997.

28C. K. Argo, P. Loria, S. H. Caldwell, and A. Lonardo, “Statins in liver disease: a molehill, an iceberg, or neither?,” Hepatol. Baltim. Md, vol. 48, no. 2, pp. 662–669, Aug. 2008.

29C. Stancu and A. Sima, “Statins: mechanism of action and effects,” J. Cell. Mol. Med., vol. 5, no. 4, pp. 378–387, Dec. 2001.

30W. Nseir and M. Mahamid, “Statins in nonalcoholic fatty liver disease and steatohepatitis: updated review,” Curr. Atheroscler. Rep., vol. 15, no. 3, p. 305, Mar. 2013.

31M. Takemoto and J. K. Liao, “Pleiotropic effects of 3-hydroxy-3-methylglutaryl coenzyme a reductase inhibitors,” Arterioscler. Thromb. Vasc. Biol., vol. 21, no. 11, pp. 1712–1719, Nov. 2001.

32A. Mallat, A. M. Preaux, S. Blazejewski, D. Dhumeaux, J. Rosenbaum, and P. Mavier, “Effect of simvastatin, an inhibitor of hydroxy-methylglutaryl coenzyme A reductase, on the growth of human Ito cells,” Hepatol. Baltim. Md, vol. 20, no. 6, pp. 1589–1594, Dec. 1994.

33R. Schierwagen et al., “Statins improve NASH via inhibition of RhoA and Ras,” Am. J. Physiol. Gastrointest. Liver Physiol., vol. 311, no. 4, pp. G724–G733, Oct. 2016.

34J. I. Yang et al., “Synergistic antifibrotic efficacy of statin and protein kinase C inhibitor in hepatic fibrosis,” Am. J. Physiol. Gastrointest. Liver Physiol., vol. 298, no. 1, pp. G126-132, Jan. 2010.

35J. Trebicka and R. Schierwagen, “Statins, Rho GTPases and KLF2: new mechanistic insight into liver fibrosis and portal hypertension,” Gut, vol. 64, no. 9, pp. 1349–1350, Sep. 2015.

36W. Wang, C. Zhao, J. Zhou, Z. Zhen, Y. Wang, and C. Shen, “Simvastatin Ameliorates Liver Fibrosis via Mediating Nitric Oxide Synthase in Rats with Non-Alcoholic Steatohepatitis-Related Liver Fibrosis,” PLOS ONE, vol. 8, no. 10, p. e76538, Oct. 2013.

37E. A. Tsochatzis and J. Bosch, “Statins in cirrhosis-Ready for prime time,” Hepatol. Baltim. Md, vol. 66, no. 3, pp. 697–699, 2017.

x

Hi!
I'm Kim!

Would you like to get a custom essay? How about receiving a customized one?

Check it out