Increased IL-23 and IL-17 expression by peripheral blood cells of patients with primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is a typical autoimmune disease for which the pathogenesis remains unclear. IL-23 and IL-17 are pro-inflammatory cytokines of the “IL-23/IL-17 axis,” which may play a key role in the pathogenesis of autoimmune diseases. In this study, we investigated the expression of IL-23 and IL-17 in the peripheral blood of patients with PBC and its clinical significance. We used quantitative PCR to determine mRNA expressions of IL-23, IL-23 receptor, and IL-17 in peripheral blood mononuclear cells (PBMC) from PBC patients. ELISA's were used to determine patients' serum levels of IL-23 and IL-17. IL-23- and IL-17-producing cells in liver biopsis were also analyzed. Compared to a healthy control group, the mRNA expression levels of IL-23 p19, its corresponding receptor, IL-23R, and IL-17 in PBMC's from PBC patients were significantly increased, and these levels were correlated with PBC disease stages. PBC patients' serum levels of IL-23 and IL-17 were higher than those in a post-hepatic cirrhosis group and a healthy group, and were significantly higher in the early PBC disease stages than in the advanced PBC stages. There were significantly more IL23+ and IL-17+ mononuclear cells in portal areas of liver tissues in advanced stages of this disease than in the early stages. The serum levels of IL-23 and IL-17 in PBC patients were positively correlated with serum GGT levels. Thus, IL-23 and IL-17 may play an important role in the pathogenesis of PBC by promoting inflammation. Because the IL-23 and IL-17 levels in the peripheral blood of PBC patients were increased and were correlated with clinical stages, they may be indices that could be used to clinically monitor PBC.