Research Note: Expression of T cell-related cytokines in chicken cecal and spleen tissues following Eimeria tenella infection in vivo.

The T cell-mediated immune response plays an important role in coccidiosis. To reveal the host T cell immune response following Eimeria tenella (E. tenella) infection in chickens, we performed quantitative real-time PCR to analyze the dynamic expression of the Th1-related cytokines IFN-γ, IL-2, and IL-12; the Th17-related cytokines IL-17A, IL-17F, and IL-22; and the Treg-related cytokines IL-10, TGF-β, and CTLA-4 in the cecum and spleen at 0, 2, 4, 6, 8, and 10 d postinfection (dpi). In the cecal tissue, the expression of the Th1-related cytokine IFN-γ was significantly higher at 6 and 8 dpi than at other time points (11.97-fold and 39.78-fold, respectively, compared with 0 dpi, P < 0.05). IL-2 and IL-12 expression was significantly higher at 6 and 8 dpi than at 0, 2 and 10 dpi (P < 0.05). The expression of the Th17-related cytokines IL-17A and IL-17F at 2 and 4 dpi and IL-22 expression at 4 dpi were significantly higher than those at 0, 6, 8 and 10 dpi (P < 0.05). The expression of the Treg-related cytokines IL-10, TGF-β and CTLA-4 was significantly higher at 6 and 8 dpi than at 0, 2 and 4 dpi (P < 0.05). In the spleen, IFN-γ and IL-12 expression peaked at 4 dpi, while IL-2 expression peaked at 10 dpi. IL-17A, IL-17F and IL-22 expression was significantly higher at 2 and 4 dpi than at 0, 6, 8 and 10 dpi (P < 0.05). Treg-related cytokine TGF-β expression was almost unchanged and significantly decreased at only 4 dpi (P < 0.05), while CTLA-4 expression showed an overall decreasing trend from 0 to 8 dpi but increased significantly at 10 dpi (P < 0.05). The expression patterns of three T cell subset-related cytokines were different in the cecum and spleen. Furthermore, Th1 and Treg cells participate in the immune response mainly in the latter stage of coccidia infection (6 and 8 dpi), while Th17 cells play a role mainly in the early stages of infection (2 and 4 dpi). Our data will help to deepen the understanding of the complex T cell immune response after coccidia infection.