The characteristics of CD4⁺T-helper cell subset differentiation in experimental Clonorchis sinensis-infected FVB mice

Immune responses are tightly regulated in the development of clonorchiasis. However, the adaptive immune regulatory pathway contributing to the pathological processes of clonorchis sinensis (C. sinensis) infection is still not clear. In this study, we assessed the dynamic changes of CD4⁺T cell subsets and the related cytokines as well as transcription factors during C. sinensis infection.

We used female FVB mice to establish the infection model. H&E and Masson's stain were performed in 2 or 8 weeks post-infection (PI) liver of C. sinensis. The percentages of splenic Th1, Th2, and Treg in CD4+T cells were detected by flow cytometry. The transcription factors T-bet, GATA3, Foxp3, and RORγt gene expression were detected by qPCR. The protein expression of IL-10, IL-17, IL-4, IL-2, and Tumor Necrosis Factor-α (TNF-α) were examined using ELISA.

The percentages of splenic Th1, Th2, and Treg in CD4⁺T cells were significantly increased in both 2 and 8 weeks PI of C. sinensis, while the ratio of Treg/Th17 as well as the percentage of Treg in serum was gradually increased during the development of infection. The expressions of T-bet, GATA3, Foxp3, and RORγt were increased in 8 weeks PI. Serum levels of IL-10, IL-17, IL-4, and IL-2 were profoundly increased in infected mice, while the concentrations of TNF-α increased to peak two weeks PI.

Our results suggested that the imbalance of CD4⁺T cell subsets may regulate and contribute to an appropriate compromise between pathology, tissue repair, and elimination in a susceptible murine host.