Regulation and function of adiponectin in the intestinal epithelial cells in response to Trichinella spiralis infection.

Besides metabolic homeostasis regulation, adipokines are recently emerged as important players in regulating immunity and inflammation. Helminth infection has known to modulate circulating adipokine secretion; however, the regulation and function of adipokines in response to helminth infection is still unclear. Here, we investigated the regulation and function of adiponectin during T. spiralis infection. While there was no change in circulating level of adiponectin, we found an increased adiponectin, but not leptin expression in the small intestine. Interestingly, the intestinal adiponectin expression was strongly associated with the expression of epithelial cell-derived cytokines IL-25, IL-33, and TSLP following infection. Indeed, mice deficiency of IL-25 receptor exhibited no intestinal adiponectin induction upon helminth infection. Interestingly, IL-25-induced adiponectin modulated intestinal epithelial cell responses by enhancing occludin and CCL17 expression. Using LPS-induced intestinal epithelial barrier dysfunctions in a Caco-2 cell monolayer model, adiponectin pretreatment enhanced a Transepithelial electrical resistance (TEER) and occludin expression. More importantly, adiponectin pretreatment of Caco2 cells prevented T. spiralis larval invasion in vitro and its administration during infection enhanced intestinal IL-13 secretion and worm expulsion in vivo. Altogether, our data suggest that intestinal adiponectin expression induced by helminth infection through the regulation of IL-25 promotes worm clearance and intestinal barrier function.