Immunopathogenesis of chronic hepatitis C virus infection

A 7-Amino Acid Peptide Mimic from Hepatitis C Virus Hypervariable Region 1 Inhibits Mouse Lung Th9 Cell Differentiation by Blocking CD81 Signaling during Allergic Lung Inflammation

T helper (Th) cells orchestrate allergic lung inflammation in asthma pathogenesis. Th9 is a novel Th cell subset that mainly produces IL-9, a potent proinflammatory cytokine in asthma. A 7-amino acid peptide (7P) of the hypervariable region 1 (HVR1) of hepatitis C virus has been identified as an important regulator in the type 2 cytokine (IL-4, IL-5, and IL-13) immune response. However, it is unknown whether 7P regulates Th9 cell differentiation during ovalbumin- (OVA-) induced allergic lung inflammation. To address this, we studied wild-type mice treated with 7P and a control peptide in an in vivo mouse model of OVA-induced allergic inflammation and an in vitro cell model of Th9 differentiation, using flow cytometry, cytokine assays, and quantitative PCR. The binding of 7P to CD81 on naïve CD4⁺ T cells during lung Th9 differentiation was determined using CD81 overexpression and siRNA knockdown analyses. Administration of 7P significantly reduced Th9 cell differentiation after OVA sensitization and exposure. 7P also inhibited Th9 cell differentiation from naïve and memory CD4⁺ T cells in vitro. Furthermore, 7P inhibited the differentiation of human Th9 cells with high CD81 expression from naïve CD4⁺ T cells by blocking CD81 signaling. CD81 siRNA significantly reduced Th9 cell differentiation from naïve CD4⁺ T cells in vitro. Interestingly, CD81 overexpression in human naïve CD4⁺ T cells also enhanced Th9 development in vitro. These data indicate that 7P may be a good candidate for reducing IL-9 production in asthma.

Long-term outcome of vertically acquired and post-transfusion hepatitis C infection in children

BACKGROUND AND AIM

To determine the natural history of perinatally acquired hepatitis C virus (HCV) infection, clinical and laboratory outcomes among 31 children with HCV infection were retrospectively reviewed. Fifteen children had acquired HCV by blood transfusion (BT) prior to 6 months of age and 16 had vertically acquired (VT) HCV.

METHODS

Demographic data, clinical symptoms and signs, liver biochemistry, HCV antibody, HCV-RNA and liver histology were evaluated.

RESULTS

Mean age at last visit was 13.0 years (range 9.0-16.8 years) in the BT group and 8.6 years (range 0.5-18.1 years) in the VT group. There were no abnormal clinical findings of chronic liver disease in either group. Estimated HCV-RNA clearance rate was 19%, with no significant difference between the groups. In HCV-RNA-negative children (n = 6), two lost anti-HCV antibody and two developed indeterminate anti-HCV antibody results, while all HCV-RNA-positive children (n = 25) remained both anti-HCV antibody positive and HCV-RNA positive throughout follow up. The alanine aminotransferase level was significantly higher in the VT group than in the BT group during the first 5 years of life. Liver biopsy, which was carried out in four children, revealed mild to moderate fibrosis and/or necroinflammatory activity, but no cirrhosis.

CONCLUSIONS

Outcomes among children with HCV acquired in infancy demonstrate asymptomatic and slowly progressive disease, at least for the initial decade of infection. Mode of acquisition appears to have a limited impact on outcomes, with similar viral clearance and anti-HCV antibody seroreversion rates in vertical and transfusion acquired infection.