Inhibitory effect of miR-125b on hepatitis C virus core protein-induced TLR2/MyD88 signaling in THP-1 cells.

AIM: To investigate the role of miR-125b in regulating monocyte immune responses induced by hepatitis C virus (HCV) core protein. METHODS: Monocytic THP-1 cells were treated with various concentrations of recombinant HCV core protein, and cytokines and miR-125b expression in these cells were analyzed. The requirement of Toll-like receptor 2 (TLR2) or MyD88 gene for HCV core protein-induced immune responses was determined by the transfection of THP-1 cells with gene knockdown vectors expressing either TLR2 siRNA or MyD88 siRNA. The effect of miR-125b overexpression on TLR2/MyD88 signaling was examined by transfecting THP-1 cells with miR-125b mimic RNA oligos. RESULTS: In response to HCV core protein stimulation, cytokine production was up-regulated and miR-125b expression was down-regulated in THP-1 cells. The modulatory effect of HCV core protein on cellular events was dose-dependent and required functional TLR2 or MyD88 gene. Forced miR-125b expression abolished the HCV core protein-induced enhancement of tumor necrosis factor-α, interleukin (IL)-6, and IL-10 expression by 66%, 54%, and 66%, respectively (P < 0.001), by inhibiting MyD88-mediated signaling, including phosphorylation of NF-κBp65, ERK, and P38. CONCLUSION: The inverse correlation between miR-125b and cytokine expression after HCV core challenge suggests that miR-125b may negatively regulate HCV-induced immune responses by targeting TLR2/MyD88 signaling in monocytes.

Involvement of TLR2-MyD88 in abnormal expression of miR-146a in peripheral blood monocytes of patients with chronic hepatitis C.

miR-146a is an immunoregulatory microRNA closely associated with viral infection. This study investigated the expression changes of miR-146a in peripheral blood monocytes of HCV-infected patients and the mechanism by which the THP-1 cells were stimulated with HCV core protein in vitro. It was found that in the peripheral blood monocytes of HCV-infected patients, miR-146a expression was upregulated. After treated by interferon/ribavirin, miR-146a expression was decreased when HCV RNA became undetectable. HCV core could directly stimulate THP-1 cells to produce miR-146a. Silencing TLR2 and MyD88 could significantly inhibit the expression of miR-146a. It was concluded that the expression of miR-146a in peripheral blood monocytes of HCV-infected patients was abnormally increased. The TLR2-MyD88 signaling pathway may take part in the overexpression of miR-146a in monocytes stimulated with HCV core protein.

Effect of the protease inhibitor MG132 on the transforming growth factor-ß/Smad signaling pathway in HSC-T6 cells.

The activation of hepatic stellate cells (HSCs) and their transformation to myofibroblasts are the key steps in the pathological progress of liver fibrosis. The transforming growth factor-ß (TGFß)/Smad pathway is involved in the proliferation and collagen synthesis of HSCs. This study aimed to examine the effect of the protease inhibitor MG132 on the signaling pathway of TGFß/Smad in HSC-T6 cells and seek a novel therapeutic approach for liver fibrosis. The HSC-T6 cells were treated with MG132 at different concentrations (0-10 µmol/L). Cell proliferation was detected by MTT method. The mRNA and protein expression levels of TGFß1, Smad3 and Smad7 were determined in HSC-T6 cells by real-time PCR and Western blotting, respectively, after treatment with MG132 at different concentrations (1, 2, 3 µmol/L) or RPMI1640 alone (serving as control). The results showed that MG132 could inhibit the proliferation of HSC-T6 cells in a dose-dependent manner, and the IC(50) of MG132 was 6.84 µmol/L. After treatment with MG132 at 1, 2 or 3 µmol/L for 24 h, the mRNA expression levels of TGF-ß1 and Smad3 were significantly decreased (P<0.05), but the Smad7 mRNA expression had no significant change (P>0.05). There was also a significant decrease in the protein expression level of TGF-ß1 and Smad3 (P<0.05). However, the expression of Smad7 protein was substantially increased when compared with the control group (P<0.05). It was concluded that the inhibition of TGFß/Smad pathway in HSC-T6 cells by MG132 can reduce the production of profibrosis factors (TGFß1, Smad3) and promote the expression of anti-fibrosis factor (Smad7), suggesting that MG132 may become a potential therapeutic alternative for liver fibrosis.

[Study on the effect of heluoshugan capsule on liver fibrosis induced by Schistosoma japonicum infection in mice].

OBJECTIVE: To investigate the effect of Chinese traditional medicine heluoshugan capsule on liver fibrosis induced by Schistosoma japonicum infection in mice. METHODS: Liver fibrosis in mice was established by Schistosoma japonicum infection in 6 weeks. Suspension of heluoshugan prepared with normal saline was given orally to the mice, 2 capsules for 20 mice daily for 8 weeks. The level of vascular endothelial growth factor (VEGF), focal adhesion kinase (FAK) and type I, III collagen in liver tissue were detected by immuno-histochemistry. RESULTS: The results showed that heluoshugan improved the pathological change of the liver tissue, decreased the level of type I, III collagen, especially type III collagen (P < 0.01). The level of VEGF and FAK expression was inhibited after the administration of heluoshugan, though the level usually increased in liver fibrosis due to the infection. CONCLUSIONS: The result suggests that heluoshugan capsule might have therapeutic effect on liver fibrosis induced by the infection of Schistosoma japonicum in mice, by inhibiting the activation of hepatic stellate cells and the pathological change of liver blood vessel.