Roles Of Altered Expressions Of IFN-gama、IL-17、IL-10 And Heat Shock Protein 70 In PI-IBS

Objective The aim of this study was to establish post-infectious irritable bowel syndrome(PI-IBS) animal model, evaluate the symptoms,detect the expressions of IFN-γ、IL-17 、IL-10 and HSP70 in intestinal tissues and the expressions of these cytokines in peripheral blood, and further to investigate the roles of the altered expressions of cytokines and HSP70 in the underlying mechanism of PI-IBS.Methods Forty female C57BL\6 mice were randomly divided into the PI-IBS group(n=20) and control group(n=20). Mice of the PI-IBS group were infected by gavaging of 350 T.spiralis larvae in 0.2 ml of normal saline, while the control group received the same volume of saline solution.At week 2,4,8 post-infection, tissues of terminal ileum and proximate colon were collected for pathological examinations. At week 8 post-infection,visceral sensitivity of colorectal distention in mice was accessed by abdominal withdrawal reflex(AWR). The change of intestinal motility was accessed by intestinal transmission time(ITT) and water content percentages of feces per 2h.The expressions of IFN-γ、IL-17 and IL-10 in different intestinal segments(duodenum, jejunum, ileum, colon) andperipheral blood were quantified by the method of ELISA. The altered expression of HSP70 in terminal ileum and proximate colon was detected by the method of immunohistochemistry, PT-PCR and Western blot.Results At week 8 post-infection, the intestinal acute inflammation recovered to normal. At distention volumes of 0.35, 0.5ml, the AWR scores of PI-IBS groups were higher than that in the control groups(P<0.01), ITT of the PI? IBS mice was shorter and the water content percentages of feces per 2h were higher than those of the control mice, and the difference was statistically significant(P<0.01). Results of ELISA showed that compared to the control mice, the IFN-γ and IL-17 levels were up-regulated in duodenum, ileum and peripheral blood(P<0.05), while IL-10 levels were decreased in jejunum, ileum, colon and peripheral blood in PI-IBS group(P<0.05). Results of immunohistochemistry showed that more HSP70 positive signals in ileum and colon of PI-IBS mice was observed compared with the control mice, and results of PT-PCR and Western blot both showed that the expression of HSP70 was significantly increased in the ileum and colon of PI-IBS group(all P<0.05).Conclusions The expression of cytokines of different intestinal segments was difference in mice with post-infectious irritable bowel syndrome and the variation trend of cytokine levels in blood and part of the bowel tissue was synchronous, which may be related to visceral hypersensitivity and intestinal motility dysfunction. The alterations ofintestinal mucosal HSP70 of PI-IBS mice may be one of causes leading to the changes of the intestinal cytokines. The high level of intestinal HSP70 in PI-IBS may reflect the chronic intestinal inflammation.