Regulatory effects of moxibustion on ubiquitin and NLRP3 proteins in colon of ulcerative colitis rats

Objective To observe the effects of moxibustion on colonic inflammation, and the expressions of ubiquitin and nucleotide-binding oligomerization domain (Nod)-like receptor protein 3 (NLRP3) proteins in rats with ulcerative colitis (UC), and to explore the anti-inflammatory mechanism of moxibustion in the UC treatment. Methods Clean grade male Sprague-Dawley (SD) rats were randomly divided into a normal group (NG), a model group (MG), a moxa-stick moxibustion group (MSMG) and a Western medicine group (WMG). UC model was prepared by freely drinking 35 g/L dextran sulfate sodium (DSS) solution. Bilateral Tianshu (ST 25) were selected for mild moxibustion treatment in the MSMG; mesalazine solution was intragastrically administrated in the WMG. Rats in the NG and MG were only grasped and fixed as in the MSMG without any treatment. After treatment, hematoxylin-eosin (HE) staining was performed to observe and score the colonic pathological damage under light microscope; immunofluorescence method was used to determine the expression of colonic ubiquitin protein; immunohistochemical method was used to detect the expressions of colonic interleukin (IL)-1β and NLRP3 proteins. Results The colon tissue was severely injured, and the pathological score was significantly increased in the MG than in the NG ( P <0.01), and the protein expressions of ubiquitin, NLRP3 and IL-1β in the colon were significantly increased (all P <0.01). Compared with the MG, the colonic damage was repaired, the inflammation and pathological scores were reduced, and the ubiquitin, NLRP3 and IL-1β protein expressions were decreased in the MSMG and WMG (all P <0.01). Correlation analysis revealed that the ubiquitin protein expression was correlated with the colonic pathological score and the NLRP3 protein expression ( r =0.677, P <0.01; r =0.536, P <0.05). Conclusion Moxibustion can down-regulate the protein expressions of ubiquitin, NLRP3 and IL-1β in the colon of UC rats, which may be one of the mechanisms to promote the repair of colonic inflammatory lesions and exert anti-inflammatory effects.