Expression of Bax, Bcl-xL and Bcl-2 proteins in relation to grade of inflammation and stage of fibrosis in chronic hepatitis C

Hepatic expression of miR-122, miR-126, miR-136 and miR-181a and their correlation to histopathological and clinical characteristics of patients with hepatitis C

It has been shown for hepatitis C virus (HCV) infection that host miRNAs contribute to the replication of the viral RNA genome. However, the clinical impact of these and many other cellular miRNAs on HCV in humans is still largely unclear. We therefore analysed the expression of miR-122, miR-126, miR-181a and miR-136 in HCV-infected patients. The study included liver biopsies of 65 patients infected with HCV of different genotypes (gt 1, gt 1a, gt 1b, gt 3 and gt 4) and nine noninfected individuals. Expression analysis of miRNAs was performed by qPCR, and they were analysed for differences between patient gender and age, genotypes, stage of fibrosis, grade of inflammation, serum level of liver enzymes, serum viral load, the presence of steatosis and mode of transmission. Different target prediction algorithms were used to search for targets of analyzed miRNAs. Statistical analysis revealed significant up-regulation of miR-136 and down-regulation of miR-126 and miR-181a in patients infected with HCV of different genotypes compared with noninfected individuals. The same expression pattern was observed in different stages and grades of liver disease. miR-122 was up-regulated in women relative to men and associated to portal inflammation, miR-122 and miR-126 correlated with serum HCV load and miR-136 and miR-122 correlated with the presence of steatosis. miR-126 and miR-136 were differentially expressed between different modes of HCV transmission. There were approximately 2000 different targets predicted for all four miRNAs and each of the analyzed miRNAs could be involved in more than a 100 different biochemical pathways. miR-122, miR-126, miR-136 and miR-181a have been shown to be involved in HCV infection with different genotypes. Their expression has been associated with the gender, stage and grade of liver disease, mode of transmission, serum HCV load and the presence of steatosis. Numerous target genes and biochemical pathways are predicted for each of the analyzed miRNAs. All these results suggest their role in HCV-infected liver disease.

Bcl-2 overexpression in hepatic stellate cell line CFSC-2G, induces a pro-fibrotic state

BACKGROUND AND AIM

Development of hepatic fibrosis is a complex process that involves oxidative stress (OS) and an altered balance between pro- and anti-apoptotic molecules. Since Bcl-2 overexpression preserves viability against OS, our objective was to address the effect of Bcl-2 overexpression in the hepatic stellate cells (HSC) cell-line CFSC-2G under acetaldehyde and H(2)O(2) challenge, and explore if it protects these cells against OS, induces replicative senescence and/or modify extracellular matrix (ECM) remodeling potential.

METHODS

To induce Bcl-2 overexpression, HSC cell line CFSC-2G was transfected by lipofection technique. Green fluorescent protein-only CFSC-2G cells were used as a control. Cell survival after H(2)O(2) treatment and total protein oxidation were assessed. To determine cell cycle arrest, proliferation-rate, DNA synthesis and senescence were assessed. Matrix metalloproteinases (MMP), tissue-inhibitor of MMP (TIMP), transglutaminases (TG) and smooth muscle a-actin (alpha-SMA) were evaluated by western blot in response to acetaldehyde treatment as markers of ECM remodeling capacity in addition to transforming growth factor-beta (TGF-beta) mRNA.

RESULTS

Cells overexpressing Bcl-2 survived approximately 20% more than control cells when exposed to H(2)O(2) and approximately 35% proteins were protected from oxidation, but Bcl-2 did not slow proliferation or induced senescence. Bcl-2 overexpression did not change alpha-SMA levels, but it increased TIMP-1 (55%), tissue transglutaminases (tTG) (25%) and TGF-beta mRNA (49%), when exposed to acetaldehyde, while MMP-13 content decreased (47%).

CONCLUSIONS

Bcl-2 overexpression protected HSC against oxidative stress but it did not induce replicative senescence. It increased TIMP-1, tTG and TGF-beta mRNA levels and decreased MMP-13 content, suggesting that Bcl-2 overexpression may play a key role in the progression of fibrosis in chronic liver diseases.

Expression of tumour necrosis factor-related apoptosis-inducing ligand and caspase-3 in relation to grade of inflammation and stage of fibrosis in chronic hepatitis C

AIM

To assess whether the distribution of the recently described proapoptotic ligand, tumour necrosis factor-related apoptosis-inducing ligand (TRAIL), and the apoptosis effector, caspase-3 alters with the degree of inflammation and fibrosis present in liver biopsy specimens from patients with chronic hepatitis C virus infection.

METHODS AND RESULTS

Expression of TRAIL and caspase-3 was assessed immunohistochemically in liver biopsy specimens obtained from 89 adults with chronic hepatitis C. Expression of TRAIL in hepatocytes correlated inversely with stage of fibrosis (P = 0.001), classified according to the Scheuer score; expression of caspase-3 in hepatocytes correlated with grade of inflammation (P = 0.012). Expression of TRAIL in hepatocytes was not correlated with grade of inflammation (P > 0.05); expression of caspase-3 was not correlated with stage of fibrosis (P > 0.05). Maximum expression of proapoptotic TRAIL protein was observed in cases with low grade inflammation (G0) and low stage fibrosis (S1). Maximum expression of caspase-3 in hepatocytes was observed in cases with high grade inflammation (G3-4) and high stage fibrosis (S3), but not with liver cirrhosis (S4).

CONCLUSIONS

There is a significant decrease in TRAIL expression with increasing grade of inflammation, whereas caspase-3 expression is significantly increased with advanced fibrosis, short of cirrhosis.