Interleukin-13 is involved in the formation of liver fibrosis in Clonorchis sinensis -infected mice

Clonorchiasis is a chronic infection disease often accompanied by formation of liver fibrosis. Previous study has identified that Clonorchis sinensis ( C. sinensis , Cs ) infection and Cs RNASET2 (a member of Cs ESPs) immunization can drive Th2 immune response. IL-13, a multifunctional Th2 cytokine, has been widely confirmed to be profibrotic mediator. We want to determine whether IL-13 is involved in the generation of liver fibrosis during C. sinensis infection. A part of mice were infected with C. sinensis or immunized with Cs RNASET2, respectively. Another part of mice were intravenously injected with rIL-13. Liver tissues of C. sinensis -infected mice were stained with hematoxylin-eosin and Masson’s trichrome, respectively. The transcriptional levels of collagen-I, collagen-III, α-SMA, and TIMP-1 in the livers of infected mice and rIL-13-treated mice were measured by quantitative RT-PCR. Besides, splenocytes of C. sinensis -infected and Cs RNASET2-immunized mice were isolated, respectively. The levels of IL-13 in splenocytes were detected by ELISA. Our results displayed that the livers of C. sinensis -infected mice had serious chronic inflammation and collagen deposition. The transcriptional levels of collagen-I, collagen-III, α-SMA, and TIMP-1 in the livers of C. sinensis -infected mice were obviously increased. Splenocytes from both C. sinensis -infected and Cs RNASET2-immunized mice expressed high levels of IL-13. Moreover, rIL-13 treatment markedly promoted the transcriptional levels of collagen-I, collagen-III, α-SMA, and TIMP-1. These data implied that hepatic fibrosis was formed in the livers of C. sinensis -infected mice, and IL-13 induced by C. sinensis infection and Cs RNASET2 immunization might favor this progression.