Interleukin-23 (IL-23) and its downstream factor IL-17 are the key cytokines involved in immune and inflammatory response in chronic liver diseases. This study aimed to investigate the role and molecular mechanisms of the IL-23/Th17 axis in chronic hepatitis C virus (HCV) infection, and the efficacy of IL-23/Th17 modulation in response to anti-HCV therapy. Sixty-six HCV-infected patients and 20 healthy controls were enrolled. The patients received PegIFNa-2a and ribavirin therapy for at least 48 weeks. The plasma level of IL-23 and the number of IL-17A-, IFN-γ-, and IL-21-producing peripheral blood mononuclear cells (PBMCs) at baseline and 12, 24, and 48 weeks following treatment were determined. The mRNA level of Th17 immune-associated molecules in PBMCs was evaluated by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) following treatment with IL-23 agonist or antagonist. Our data showed that, compared to healthy controls, HCV-infected patients had an increased plasma level of IL-23 and increased frequencies of IL-17A- and IFN-γ-producing PBMCs, whereas the HCV patients exhibited a reduced number of IL-21-producing PBMCs. However, the baseline frequencies of IL-21-producing PBMCs were markedly higher in HCV patients who achieved rapid virological response (RVR) than those without RVR. Additionally, the mRNA expressions of IL-21, IFN-γ, myxovirus resistance protein A (MxA), and suppressor of cytokine signaling 3 (SOCS3) were significantly upregulated in PBMCs, while FoxP3 expression was suppressed by IL-23 agonist. Thus, the IL-23/Th17 axis plays an important role in development of chronic HCV infection and antiviral response. IL-23 may enhance the antiviral activity of interferon-based therapy by modulating the expression of Th17 cells-associated molecules in HCV-infected patients.

To investigate the potential role of heme oxygenase-1 on preventing non-alcoholic steatohepatitis (NASH) in mice. Experimental models of NASH were established by feeding male C57BL/6J mice with choline-methionine deficient diet (MCD) for four weeks. Control animals were fed with choline-methionine supplemented diet. The treatment groups were fed with MCD diet combined with HO-1 inducer hemin or inhibitor zinc protoporphyrin IX (ZnPP-IX). Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were tested by enzymic method with automatic biochemistry analyzer. The degree of hepatic steatosis, inflammation and fibrosis were examined under HE staining. The hepatic mRNA and protein expressions of HO-1, TNFalpha and IL-6 were analyzed by RT-PCR and Western blot respectively. MCD fed mice showed increased serum ALT and AST levels and moderate to severe hepatic steatosis with inflammatory infiltration, hepatic spot or focal necrosis, light portal and sinus hepaticus fibrosis in the liver sections, which associated with enhanced expression of HO-1, TNFalpha and IL-6 mRNA and protein (1.13+/-0.11, 1.74+/-0.05; 0.20+/-0.01, 1.92+/-0.10; 0.58+/-0.02, 2.06+/-0.05 vs 0.43+/-0.02, 0.75+/-0.05; 0.08+/-0.00, 0.59+/-0.02; 0.22+/-0.01, 0.91+/-0.02). Administration of hemin significantly decreased serum ALT and AST levels and attenuated hepatic steatosis and necroinflammation which associated with up-regulation of antioxidative gene HO-1 and down-regulation of pro-inflammatory cytokines TNFalpha and IL-6 (P < 0.01). A contrary effect on serum aminotransferase levels and liver histopathology was observed in mice injected with ZnPP-IX (P < 0.01). The effect was associated with suppressed HO-1 expression and increased TNFaLPHA and IL-6 expression. The data provided a biochemical, morphological and molecular biological evidence for the protective role of HO-1 in ameliorating hepatic steatosis, necroinflammation in experimental nutritional steatohepatitis.