Large numbers of interleukins-22- and -17A-producing T helper cells in cholangiocarcinoma related to liver fluke infection

Abstract

Cholangiocarcinoma (CCA) associated with liver fluke infection involves inflammatory and immune processes; however, whether these involve the proinflammatory cytokine IL-17A and proliferative cytokine IL-22 remains unclear. Here, numbers of IL-22- and IL-17A-producing Th cells and cytokine concentrations in 30 patients with CCA and long-term liver fluke infection, 40 patients with liver-fluke infection but not CCA, and 16 healthy controls were compared. Analyses were performed using immunohistochemistry, flow cytometry, ELISA and RT-PCR. Immunohistochemical staining showed weaker expression of IL-22 and IL-17A in patients with CCA with than in those without liver fluke infection (P < 0.01). Flow cytometry revealed significantly greater median proportions of IL-22-producing T helper cells in patients with CCA (2.2%) than in those without it (0.69%) or controls (0.4%, P < 0.001). Similar results were obtained for IL-17A-producing T helper cells. ELISA revealed plasma concentrations of IL-22 were 1.3-fold higher in patients with CCA than in those without it and 4.6-fold higher than in controls (P < 0.001). Plasma concentrations of IL-17A were 2.5-fold higher in patients with CCA than in those without it, and 21-fold higher than in controls (P < 0.001). Amounts of IL-22 and IL-17A mRNAs in blood were significantly higher in patients with CCA than in the other two groups. Proportions of CD4⁺ CD45RO⁺ T cells producing IL-22 correlated with proportions producing IL-17A (r = 0.759; P < 0.001), and plasma concentrations of IL-22 correlated with those of IL-17A (r = 0.726; P < 0.001). These results suggest that both IL-17A and IL-22 affect development of CCA related to liver fluke infection.

Keywords: cholangiocarcinoma; interleukin-17A; interleukin-22; liver fluke.