Moxibustion relieves colonic inflammation by up-regulating expression of miR-345-3p/miR-216a-5p and down-regulating NF-κB p65 in colonic tissue of rats with diarrhea-predominant irritable bowel syndrome

Abstract

To observe the effect of moxibustion on the expression of miR-345-3p, miR-216a-5p and nuclear factor-κB p65(NF-κB p65) in colonic tissue of rats with diarrhea-predominant irritable bowel syndrome (IBS-D), so as to explore its anti-inflammatory mechanism in relieving IBS-D. SD rats were randomly divided into normal control (n=12), model (n=12), moxibustion (n=12) and ammonium pyrrolidine dithiocarbamate (PDTC,n=12) groups. The IBS-D model was established by neonatal mother-child separation combined with acetic acid enema stimulation and chronic binding methods. The rats in the moxibustion group received moxibustion stimulation of "Tianshu"(ST25) and "Shangjuxu"(ST37) for 20 min, once a day, for 7 days, and those of the PDTC group received intraperitoneal injection of PDTC (50 mg·kg-1·d-1) once daily for 7 days. After the intervention, the body weight, loose stool rate and the minimum volume threshold of abdominal withdrawal reflex (AWR) were observed, and histopathological changes of colonic mucosa were observed by HE staining. The contents of interleukin-1β (IL-1β), interleukin-4 (IL-4), interleukin-6 (IL-6) and tumor necrosis factor α (TNF- α) in serum were measured by ELISA. The expression of miR-345-3p, miR-216a-5p and NF-κB p65 mRNA in the colon tissue were detected by quantitative real-time PCR, and the immunoactivities of IL-1β, IL-6, TNF-α and NF-κB p65 in the colon tissue were determined by immunofluorescence histochemistry. Compared with the normal control group, the loose stool rate, contents of IL-1β, IL-6 and TNF-α, experssion of NF-κB p65 mRNA and the immunoactivities of IL-1β, IL-6, TNF-α and NF-κB p65 were significantly increased (P<0.01), whereas the body weight, minimum volume threshold of AWR, content of IL-4, and the relative expression of miR-345-3p and miR-216a-5p were remarkably decreased in the model group (P<0.01). In comparison with the model group, the loose stool rate, contents of IL-1β, IL-6, TNF-α, expression of NF-κB p65 mRNA and the immunoactivities of IL-1β, IL-6, TNF-α and NF-κB p65 were considerably down-regulated (P<0.01), while the content of IL-4 and the relative expressions of miR-345-3p and miR-216a-5p were obviously up-regulated in both moxibustion and PDTC groups (P<0.01, P<0.05). The content of IL-6 in serum was significantly lower in the PDTC group than in the moxibustion group (P<0.01). Moxibustion can reduce the level of intestinal inflammation and visceral hypersensitivity in IBS-D rats, which may be related to its functions in increasing the expression levels of miR-345-3p and miR-216a-5p and in inhibiting the expression of NF-κB p65, thus reducing the levels of inflammatory factors.