Regulation of anti-inflammatory cytokines IL-10 and TGF-β in mouse dendritic cells through treatment with Clonorchis sinensis crude antigen

Dendritic cells (DCs), which are regarded as the most potent antigen-presenting cells, are involved in innate and adaptive immunity. Upon uptake of pathogens, DCs express cell surface markers and secrete cytokines. In this study, we analyzed production of cytokines and found that interleukin (IL)-10 and transforming growth factor (TGF)-β production significantly increased in bone marrow-derived DCs and a mouse DC line, DC2.4, after treatment with crude antigen (CA) from liver fluke, Clonorchis sinensis. However, expression patterns of several activation molecules did not change. In addition, following treatment of DC2.4 cells with antigen from the lung fluke, Paragonimus westermani, production of IL-10 and TGF-β significantly increased compared with groups treated with other parasite antigens, Spirometra erinacei plerocercoid CA and Echinococcus granulosus hydatid cystic fluid. We also found that treatment of DC2.4 cells with C. sinensis CA resulted in rapid and significant phosphorylation of extracellular signal-regulated kinase 1/2, a mitogen-activated protein kinase. Following treatment of DC2.4 cells with C. sinensis CA, treatment with an inhibitor specific to an extracellular signal-regulated kinase inhibited production of IL-10 and TGF-β. Our results suggest that CA from C. sinensis has a role in the anti-inflammatory function of DC cells by inducing IL-10 and TGF-β through activation of extracellular signal-regulated kinase 1/2.