The role of IDO, IL‐10, and TGF‐β in the HCV‐associated chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma

Indoleamine‐2,3‐dioxygenase (IDO) is an enzyme that catalyzes tryptophan to kynurenine and studies have revealed that IDO play a vital role in regulation of liver immunity and inflammation activities. This study investigated the association between plasma IDO and disease severity and the possible marker role of IDO in the inflammatory process of hepatitis C. In this study, 80 individuals with HCV infection were retrospectively selected. Plasma levels of IDO, IL‐10, and TGF‐β were assayed by ELISA. Clinical characteristics of patients, including the levels of ALT, AST, and total bilirubin (TBil) were collected from clinical databases. HCV‐related liver cirrhosis (HC‐Cirr) and HCV‐related Hepatocellular carcinoma (HCV‐HCC) had significantly high plasma levels of IDO compared to other patient groups and healthy controls. Plasma IL‐10 level were significantly greater in all chronic liver disease groups and with respect to TGF‐β, the level was high in all the selected patients with HCV infection compare with controls. Moreover, HCV‐HCC patients showed highest values for both IL‐10 and TGF‐β, with significant difference compared with other groups. In addition, plasma IDO was positively correlated with TGF‐β among all patients with HCV infection (r = 0.4509, P