Immunopathological mechanism of TNBS-induced inflammatory bowel disease in mice / 中华微生物学和免疫学杂志

ABSTRACT

Objective To study the possible pathogenesis of TNBS (2,4,6-trinitrobenzenesulfonic acid)-induced inflammatory bowel disease (IBD) in a mouse model by analyzing histological changes in colon and the expression of cytokines and transcription factor RORγt related to T cell subsets in mesenteric lymph nodes.Methods Female BALB/c mice aged 6-8 weeks were randomly grouped into two groups IBD model and normal control groups.The mouse model of IBD was established by treating mice with 200 μl of 5％ TNBS/50％ ethanol solution (1∶1) through intestinal instillation, while the mice in the normal control group were instilled with PBS.Pathological changes in colon samples of mice were observed.Real-time PCR was performed to detect the dynamic expression of Th1 cytokines (IL-2, IFN-γ and IL-12p40), Th2 cytokine (IL-4), Treg-related cytokine (IL-10), Th17 cell-related cytokines (IL-17, IL-21 and IL-23) and transcription factor RORγt in mesenteric lymph nodes.Results The mice in the model group begun to show abnormal vital signs such as diarrhea, loss of weight and reduced activity, and mild hyperemia of intestinal mucosa and edema from the third day after modeling.Slight lesions were observed in histological slices of colon tissues stained with hematoxylin and eosin (HE).The expression of IL-21, IL-23 and IL-17 at mRNA level were significantly increased, while the expression of other cytokines showed no significant change.On the sixth day after modeling, many pathological symptoms and intestinal mucosal lesions were aggravated, and marked infiltration of inflammatory cells was observed in histological slices of colon tissues, which indicated that the IBD model was successfully induced by TNBS.Compared with the control group, the IBD model group showed significantly enhanced expression of IL-2, IL-12p40 and IL-10 in mesenteric lymph nodes at mRNA level on the sixth day after modeling.Although the expression of IL-21, IL-23, IL-17 and RORγt at mRNA level on the sixth day were down-regulated to different extent as compared with those on the third day, they were still significantly higher than those of the control group.Conclusion Th17 cell-related cytokines play an important role in the early stage of TNBS-induced IBD.With the progression of the disease, both Th1 and Th17 cells are involved in the immunopathological injury of colon tissues.