Effect Of Dendritic Cells From Intestinal Lamina Propria On Activation Of Cd4~+ T Cells In Post-infectious Visceral Hypersensitivity Mice

Background: More and more evidences indicate that T cell-mediated low-grade inflammation presents in intestinal mucosa of post-infectious irritable bowel syndrome (PI-IBS). Dendritic cells (DC) are the most important antigen presenting cells in intestinal mucosal immune system, however, its role in the initiation of PI-IBS is still uncertain.Aims To investigate the effect of DC from intestinal lamina propria on CD4~+ T cells in different phases of acute intestinal infection, and its role in sustained activation of intestinal mucosal immune system after recovery of intestinal infection.Methods Visceral hypersensitivity was induced by Trichinella spiralis infection in mice to mimic human PI-IBS. DC in intestinal lamina propria and CD4~+ T cells in spleen were isolated by MACS? MicroBeads and cocultured in vitro for 120 hours, the Th17, Th2 and Th1 related cytokines (IL-17, IL-4 and IFN-γ) and IL-23 in the supernatant were determined by ELISA.Results Compared with CD4~+ T cells cultured alone, the increment of IL-17 in supernatant of CD4~+ T cells cocultured with DC was significantly higher in 8-week PI group than that in control group ( P=0.001) and 2-week PI group (P=0.279); the increment of IL-4 was significantly higher in 2-week PI group than that in contral group (P=0.041) and 8-week PI group (P=0.204); no significant difference was found in the increment of IFN-γamong the three groups;In vitro dendritic cell culture, IL-23 secretion significantly increased in 8-week PI group compared with normal control group (P=0.043) or 2-week PI group (P=0.041).Conclusions DC from intestinal lamina propria in PI visceral hypersensitivity mice can effectively promote the activativation of Th17 cells, which might be the main mechanism of sustained activation of intestinal mucosal immune system after recovery of intestinal infection.