Th17 cells influence intestinal muscle contraction during Trichinella spiralis infection

Trichinella spiralis infection in rodents is a well-known model of intestinal inflammation associated with hypermotility. The aim of the study was to use this experimental model to elucidate if Th17 cells are involved in the development of gastrointestinal hypermotility. Colonic smooth muscle contractility was investigated in response to acetylcholine. The levels of IL-17, IL-23 and TGF-β1 in colon were measured by Western blotting. Flow cytometric detection of intracellular IFN-γ/IL-4/IL-17 cytokine production was used to analyze the proportions of CD4+ T cells subsets in colon. Our results showed that colonic muscle contractility was increased 2 weeks post infection (PI) and stayed high 12 weeks PI when no discernible inflammation was present in the gut. The proportion of Th17 cells and the expression of IL-17 were up-regulated in colon 2 weeks PI and returned to normal 8 weeks PI. The content of IL-17 was correlated with the colonic smooth muscle hypercontracility 2 weeks PI. Meanwhile, TGF-β1 was increased 2 weeks PI, while IL-23 was normal. Our results suggest that Th17 cells affect the colonic muscle contractility in mice infected with Trichinella spiralis at intestine stage but not at muscle stage and the effect of Th17 cells on muscle contractility might be induced by TGF-β1. Other cytokines might be involved in the hypercontracility of colonic smooth muscle at muscle stage.