Peripheral blood and hepatic Toll-like receptor 7 expression and interferon lambda 1 levels in chronic hepatitis C: Relation to virus replication and liver injury.

BACKGROUND AND AIM: Toll-like receptor 7 (TLR7) can recognize single-stranded RNA viruses like hepatitis C virus (HCV) with subsequent induction of different interferon (IFN) types including IFN lambda (IFNL), which activate an immediate anti-viral response. However, the role of TLR7 in inflammation and fibrosis, characteristics of HCV-induced liver injury, is still controversial. The present work was designed to investigate the potential role of TLR7 and IFNL1 in chronic hepatitis C (CHC) in relation to viral replication and liver injury. METHODS: Forty two treatment-naïve patients with CHC and 20 healthy subjects were enrolled in the study. TLR7 expression on peripheral blood CD14+ monocytes was studied by color flow cytometry and the frequency of TLR7+CD14+ cells was expressed as percentage of total monocyte count. Quantification of IFNL1 levels in serum was determined using enzyme-linked immunosorbant assay. Liver biopsies were examined for assessment of histological activity grade (A0-A3) and fibrosis stage (F0-F4) according to METAVIR scoring system as well as steatosis grade. Immunohistochemical staining was performed using human antibodies against TLR7 and IFNL1 and was scored semi-quantitatively (score 0-3). Hepatic expression of TLR7 and IFNL1 was further classified using a two-grade scale as low expression (score 0 or 1) and high expression (score 2 or 3). RESULTS: Percentages of circulating TLR7+CD14+ monocytes and serum IFNL1 levels were significantly higher in patients with CHC than in healthy controls (P = 0.025 and P < 0.001 respectively) and were positively correlated with corresponding hepatic TLR7 and IFNL1 expression (P < 0.001 and P = 0.010 respectively). Significantly lower peripheral blood and hepatic TLR7 expression and IFNL1 levels were found in patients with viral loads between 200,000-600,000 IU/ml and >600,000 IU/ml than in those with viral load <200,000 IU/ml (P < 0.05), in patients with severe necroinflammation than in those with mild-to-moderate necroinflammation (P < 0.05) and in patients with advanced fibrosis than in those with early fibrosis (P < 0.01). Also, changes in TLR7 expression and IFNL1 production in peripheral blood and the liver were inversely correlated with serum levels of aspartate and alanine aminotransferases (P < 0.05) and HCV RNA (P < 0.01), histological activity grade (P < 0.01) and fibrosis stage (P < 0.01). By plotting receiver operating characteristics (ROC) curve, serum IFNL1 showed higher sensitivity and specificity than percentages of circulating TLR7+CD14+ monocytes in discriminating patients with CHC according to the severity of hepatic necroinflammation (area under the curve (AUC) = 0.901 vs. 0.816 respectively) and fibrosis (AUC = 0.971 vs. 0.825 respectively) at a cut-off value of 44.75 pg/ml and 10.25% respectively. CONCLUSIONS: TLR7 activation and IFNL1 production in CHC may play an important role in controlling viral replication and limiting hepatic inflammation and fibrosis and their downregulation may result in viral persistence and disease progression. The immunoregulatory role of TLR7-IFNL1 pathway in the pathogenesis of chronic HCV infection should be further studied. Clinical trials with a large number of patients are needed to assess the usefulness of serum IFNL1 as a potential biomarker for severity of liver injury in chronic HCV infection and other liver diseases.

Circulating anti-HLA antibodies in patients with chronic hepatitis C: relation to disease activity.

The human leukocyte antigens (HLA) may influence host immune to infection. In the mean time chronic hepatitis C (CHC) results in the appearance of a variety of autoantibodies. We investigated the frequency of circulating anti-HLA antibodies and none organ specific autoantibodies in patients with chronic hepatitis C at different stages of disease activity. Sixty-seven untreated male patients with CHC (anti-HCV antibody and HCV RNA positive), in whom 38 had elevated serum alanine aminotransferase (ALT) levels and 29 persistently normal serum ALT values, and 23 age-matched normal male subjects were studied. None of them had a history of blood transfusion. Sera were analyzed for immunoglobulin G-anti-HLA class I and class II antibodies by enzyme-linked immunosorbant assay, and for non-organ-specific autoantibodies (antinuclear, anti-smooth muscle, anti-mitochondrial and anti-liver/kidney microsomes type 1 antibodies) using indirect immunofluorescence technique. Circulating anti-HLA class I and class II antibodies were detected in 15/67 (22.4 %) and 11/67 (16.4 %) respectively, while none of normal controls had detectable anti-HLA antibodies in the serum. The frequency of detecting anti-HLA antibodies was significantly higher in patients with elevated serum ALT than persistently normal serum ALT values (31.6 % vs 10.3 %; P = 0.039) and was associated with non-organ-specific serum autoantibodies in 11/15 (73.3 %) patients. Those with circulating anti-HLA antibodies had significantly higher levels of serum aminotransferases, gamma-glutamyl transpeptidase, viral load and necroinflammatory and fibrosis scores in liver biopsies than patients with negative anti-HLA antibody (P < 0.001). In conclusions, the presence of circulating antibodies against HLA class I and class II molecules in HCV antibodies may represent an autoimmune response to HLA antigens and may play a pathogenetic role in the induction of the HCV-related chronic liver disease.