New approaches for fibrosis regression in alcoholic cirrhosis

CD73-Adenosine A1R Axis Regulates the Activation and Apoptosis of Hepatic Stellate Cells Through the PLC-IP3-Ca2+/DAG-PKC Signaling Pathway

Alcohol-related liver fibrosis (ALF) is a form of alcohol-related liver disease (ALD) that generally occurs in response to heavy long-term drinking. Ecto-5'-nucleotidase (NT5E), also known as CD73, is a cytomembrane protein linked to the cell membrane via a GPI anchor that regulates the conversion of extracellular ATP to adenosine. Adenosine and its receptors are important regulators of the cellular response. Previous studies showed that CD73 and adenosine A1 receptor (A1R) were important in alcohol-related liver disease, however the exact mechanism is unclear. The aim of this study was to elucidate the role and mechanism of the CD73-A1R axis in both a murine model of alcohol and carbon tetrachloride (CCl4) induced ALF and in an in vitro model of fibrosis induced by acetaldehyde. The degree of liver injury was determined by measuring serum AST and ALT levels, H & E staining, and Masson's trichrome staining. The expression levels of fibrosis indicators and PLC-IP3-Ca2+/DAG-PKC signaling pathway were detected by quantitative real-time PCR, western blotting, ELISA, and calcium assay. Hepatic stellate cell (HSC) apoptosis was detected using the Annexin V-FITC/PI cell apoptosis detection kit. Knockdown of CD73 significantly attenuated the accumulation of α-SMA and COL1a1 damaged the histological architecture of the mouse liver induced by alcohol and CCl4. In vitro, CD73 inhibition attenuated acetaldehyde-induced fibrosis and downregulated A1R expression in HSC-T6 cells. Inhibition of CD73/A1R downregulated the expression of the PLC-IP3-Ca2+/DAG-PKC signaling pathway. In addition, silencing of CD73/A1R promoted apoptosis in HSC-T6 cells. In conclusion, the CD73-A1R axis can regulate the activation and apoptosis of HSCs through the PLC-IP3-Ca2+/DAG-PKC signaling pathway.

Alcoholic and Non-Alcoholic Liver Diseases: Promising Molecular Drug Targets and their Clinical Development

Alcoholic and non-alcoholic fatty liver diseases have become a serious concern worldwide. Both these liver diseases have an identical pathology, starting from simple steatosis to cirrhosis and, ultimately to hepatocellular carcinoma. Treatment options for alcoholic liver disease (ALD) are still the same as they were 50 years ago which include corticosteroids, pentoxifylline, antioxidants, nutritional support and abstinence; and for non-alcoholic fatty liver disease (NAFLD), weight loss, insulin sensitizers, lipid-lowering agents and anti-oxidants are the only treatment options. Despite broad research in understanding the disease pathophysiology, limited treatments are available for clinical use. Some therapeutic strategies based on targeting a specific molecule have been developed to lessen the consequences of disease and are under clinical investigation. Therefore, focus on multiple molecular targets will help develop an efficient therapeutic strategy. This review comprises a brief overview of the pathogenesis of ALD and NAFLD; recent molecular drug targets explored for ALD and NAFLD that may prove to be effective for multiple therapeutic regimens and also the clinical status of these promising drug targets for liver diseases.

Collagen type IV remodelling gender-specifically predicts mortality in decompensated cirrhosis

BACKGROUND & AIMS

Remodelling of extracellular matrix is crucial in progressive liver fibrosis. Collagen type III desposition has been shown in acute decompensation. Extratracellular matrix is compiled of deposition of various components. The role of basement membrane collagen type IV in advanced cirrhosis and acute decompensation is unclear and investigated in this study.

METHODS

Patients with decompensated cirrhosis from the prospective NEPTUN cohort (ClinicalTrials.gov Identifier: NCT03628807), who underwent transjugular intrahepatic portosystemic shunt procedure were included. Clinical and laboratory parameters, PRO-C4 and C4M levels were measured in blood samples from portal and hepatic veins just before transjugular intrahepatic portosystemic shunt placement.

RESULTS

Levels of C4M and PRO-C4 are significantly lower in patients with massive ascites and impaired renal sodium excretion. C4M and PRO-C4 show gender-specific profiles with significantly lower levels in females compared to males. Females with higher C4M levels show higher mortality. By contrast, males with higher C4M levels show lower mortality. In multivariate Cox regression analysis, C4M is an independent predictor of survival in female patients.

CONCLUSION

This study shows that markers of collagen type IV remodelling do not accumulate in severe renal dysfunction. Although collagen type IV degradation markers derive from the liver, portal venous C4M levels are relevant for survival. Moreover, it demonstrates that circulating C4M shows gender-specific profiles, which can independently predict survival in female patients with decompensated cirrhosis.

Acute decompensation boosts hepatic collagen type III deposition and deteriorates experimental and human cirrhosis

Patients with end-stage liver disease develop acute decompensation (AD) episodes, which become more frequent and might develop into acute-on-chronic liver failure (ACLF). However, it remains unknown how AD induces acceleration of liver disease. We hypothesized that remodeling of collagen type III plays a role in the acceleration of liver cirrhosis after AD and analyzed its formation (Pro-C3) and degradation (matrix metalloproteinase-degraded type III collagen [C3M]) markers in animal models and human disease. Bile duct ligation induced different stages of liver fibrosis in rats. Fibrosis development (hydroxyprolin content, sirius red staining, α-smooth muscle actin immunohistochemistry, messenger RNA of profibrotic cytokines), necroinflammation (aminotransferases levels), fibrolysis (matrix metalloproteinase 2 expression and activity, C1M, C4M), and Pro-C3 and C3M were analyzed 2, 3, 4, 5, and 6 weeks after bile duct ligation (n = 5 each group). In 110 patients with decompensated liver cirrhosis who underwent a transjugular intrahepatic portosystemic shunt procedure for AD, clinical and laboratory parameters as well as Pro-C3 and C3M were measured in blood samples from portal and hepatic veins and were collected just before the transjugular intrahepatic portosystemic shunt placement and 1-3 weeks later. Animal studies showed increased markers of collagen type III deposition with fibrosis, necroinflammation, and decompensation of liver cirrhosis, defined as ascites development. Higher Pro-C3 levels were associated with injury, disease severity scores (Model for End-Stage Liver Disease, Child-Pugh, chronic liver failure-C AD), ACLF development, and mortality. C3M decreased with AD and the chronic liver failure-C AD score. Collagen type III deposition ratio increased with the risk of ACLF development and mortality. Conclusion: We show for the first time that AD boosts collagen type III deposition in experimental and human cirrhosis, possibly contributing to the worsened outcome in patients with decompensated cirrhosis. (Hepatology Communications 2018;2:211-222).

Injury and defective regeneration of the epithelial basement membrane in corneal fibrosis: A paradigm for fibrosis in other organs?

Myofibroblast-mediated fibrosis is important in the pathophysiology of diseases in most organs. The cornea, the transparent anterior wall of the eye that functions to focus light on the retina, is commonly affected by fibrosis and provides an optimal model due to its simplicity and accessibility. Severe injuries to the cornea, including infection, surgery, and trauma, may trigger the development of myofibroblasts and fibrosis in the normally transparent connective tissue stroma. Ultrastructural studies have demonstrated that defective epithelial basement membrane (EBM) regeneration after injury underlies the development of myofibroblasts from both bone marrow- and keratocyte-derived precursor cells in the cornea. Defective EBM permits epithelium-derived transforming growth factor beta, platelet-derived growth factor, and likely other modulators, to penetrate the stroma at sustained levels necessary to drive the development of vimentin+ alpha-smooth muscle actin+ desmin+ (V+A+D+) mature myofibroblasts and promote their persistence. Defective versus normal EBM regeneration likely relates to the severity of the stromal injury and a resulting decrease in fibroblasts (keratocytes) and their contribution of EBM components, including laminin alpha-3 and nidogen-2. Corneal fibrosis may resolve over a period of months to years if the inciting injury is eliminated through keratocyte-facilitated regeneration of normal EBM, ensuing apoptosis of myofibroblasts, and reorganization of disordered extracellular matrix by repopulating keratocytes. We hypothesize the corneal model of fibrosis associated with defective BM regeneration and myofibroblast development after epithelial or parenchymal injury may be a paradigm for the development of fibrosis in other organs where chronic injury or defective BM underlies the pathophysiology of disease.