Study of the mechanism of acupuncture and moxibustion in protecting the intestinal mucosal barrier in DSS-induced UC rats based on the IL-9/IL-9R pathway

Objective: To observe the effects of acupuncture and moxibustion on interleukin (IL)-9/IL-9 receptor (IL-9R) in the colon tissue of rats with ulcerative colitis (UC) and investigate the protective mechanism of acupuncture and moxibustion on the intestinal mucosal barrier in UC rats. Methods: Male Sprague-Dawley rats were randomly divided into a normal control (NC) group and a modeling group. UC models were prepared by giving 4% dextran sulfate sodium (DSS) water for 7 d. After the successful construction of the UC rat model, the modeling group was randomly divided into a UC group, a herb-partitioned moxibustion (HM) group, and an electroacupuncture (EA) group. HM and EA interventions at bilateral Tianshu (ST25) were performed once a day for 7 d. Hematoxylin-eosin (HE) staining was used to observe the histopathological changes in the colon. The serum concentrations of IL-9, IL-6, IL-1 beta, and hemoglobin-H (HbH) were determined by enzyme-linked immunosorbent assay. The protein expression levels of IL-9, IL-9R, Claudin-2, zonula occludens-1 (ZO-1), and occludin in the colon tissue were measured by Western blotting or immunohistochemistry. Immunofluorescence was used to detect the co-expression of PU.1 and CD4 with the IL-9 protein. Results: Compared with the NC group, the colon tissue of UC rats was severely damaged and ulcerated with congestion and edema, and the colonic histopathological score increased significantly (P<0.01). The serum HbH concentration decreased significantly (P<0.01), while the serum concentrations of IL-9, IL-6, and IL-1 beta increased (P<0.01). The protein expression of colonic ZO-1 and occludin decreased significantly (P<0.01), while the protein expression of colonic IL-9 and IL-9R increased (P<0.05). The positive co-expression levels of IL-9/PU.1 and IL-9/CD4 increased in the colon tissue (P<0.05). Compared with the UC group, the colonic mucosal structures were gradually repaired in both HM group and EA group, and healed ulcers could be observed, the colonic histopathological score decreased significantly (P<0.05). The serum concentration of HbH increased (P<0.01), while the serum concentrations of IL-9, IL-6, and IL-1 beta decreased (P<0.05). The protein expression levels of ZO-1 and occludin increased (P<0.05), while the protein expression levels of IL-9 and IL-9R decreased (P<0.01). The positive co-expression levels of IL-9/PU.1 and IL-9/CD4 decreased in the colon tissue (P<0.05). Conclusion: Both HM and EA can inhibit the protein expression levels of IL-9 and IL-9R in the UC colon by regulating the transcription factor PU.1, promote the repair of intestinal mucosal barrier, and down-regulate protein contents of proinflammatory factors IL-9, IL-6, and IL-1 beta in the serum, which may be one of the key mechanisms of acupuncture and moxibustion in reducing the inflammation of UC colonic mucosa and protecting the intestinal mucosal barrier.