The Effect Of Aryl Hydrocarbon Receptor On Th17Cells Activation In A Muirne Model With Irritable Bowel Syndrome

ObjectivesTo detect the dynamic Th1, Th2and Th17cells activation in a murine model ofirritable bowel syndrome (IBS) and to study the effect of aryl hydrocarbon receptor(Ahr) on Th17cells activation.MethodsThirty Balb/c male mice were randomly divided into three groups includingexperimental group, control group and Ahr antagonist group. A murine model of IBSwas established by perfusing trinitrobenzene sulfonic acid (TNBS) into the colon ofmice. Equal volume of saline was used to set up the control. The mice in Ahrantagonist group were intraperitoneally injected with10μg Ahr antagonist fourconsecutive days. All mice were evaluated for visceral hypersensitivity and colonicmucosal inflammation. Mesenteric lymph nodes(MLNs) and peripheral bloodmononuclear cells(PBMCs) were detected by flow cytometry through staining Th1,Th2and Th17cells. The distribution of Ahr and IL-17A in colon and the number ofTh17cells activated by Ahr (Ahr and IL-17A double positive) were detected by double immunofluorescence staining.Results①At the pressure of20mmHg、40mmHg、80mmHg in the colorectal distensionexperiment, the abdominal withdrawal reflex score were higher in the experimentalgroup and the Ahr antagonist group as compared with controls(P <0.05); whilecompared with the experimental group, the score in the Ahr antagonist groupdecreased significantly(P <0.05). Compared with the control group, there were nosignificantly gross and histological inflammation observed in murine colonic mucosaof the experimental group and the Ahr antagonist group.②In MLNs, the frequenciesof Th1、Th2and Th17cells increased significantly in both the experimental group andthe Ahr antagonist group as compared with controls (both P <0.05); and theproportion of Th17cells decreased significantly in the Ahr antagonist group ascompared with the experimental group (P <0.05) which was still higher in the Ahrantagonist group as compared with controls(P <0.05).③In peripheral blood samples,the frequencies of Th1and Th17cells increased significantly in both the experimentalgroup and the Ahr antagonist group as compared with controls (both P <0.05), whilethe frequency of Th2cells decreased significantly (P <0.05); and no difference couldbe observed in the proportion of Th17cells in the Ahr antagonist group and theexperimental group (P=0.642).④In colonic mucosa, compared with the controlgroup, Th17cells activated by Ahr (Ahr+IL-17A+) count increased significantly inboth the experimental group (10.0±1.58vs3.8±0.83, P <0.05) and the Ahr antagonistgroup (5.8±0.83vs3.8±0.83, P <0.05); however, Th17cells activated by Ahrdecreased significantly in the Ahr antagonist group as compared with theexperimental group (5.8±0.83vs10.0±1.58, P <0.05).ConclusionsTNBS induced a murine visceral hypersensitivity model with irritable bowelsyndrome. The proportion of Th1/Th2cells was out of banlance and the number ofactivated Th17cells was increased in MLNs and peripheral blood samples form micewith IBS, abnormal immune activation of intestinal mucosa could lead to low grademucosal inflammation. Ahr played an important role in intestinal Th17cellsactivation. However, the number of Ahr-activated Th17cells in intestinal mucosa and the proportion of Th17cells in MLNs could be down-regulated through blocking Ahr.