Effects of electroacupuncture with "intestinal disease prescription" on NLRP3 inflammasome and intestinal mucosal barrier in rats with acute ulcerative colitis.

OBJECTIVES

To observe the effects of electroacupuncture (EA) with "intestinal disease prescription" on the intestinal mucosal barrier and NLRP3 inflammasome in rats with dextran sulfate sodium (DSS)-induced acute ulcerative colitis (UC), and explore the underlying mechanism of EA with "intestinal disease prescription" for the treatment of UC.

METHODS

Thirty-two healthy male SPF-grade SD rats were randomly divided into a blank group, a model group, a medication group, and an EA group, with 8 rats in each group. Except for the blank group, the UC model was established by administering 5% DSS solution for 7 days. After modeling, the rats in the medication group were treated with mesalazine suspension (200 mg/kg) by gavage, while the rats in the EA group were treated with acupuncture at bilateral "Tianshu" (ST 25), "Shangjuxu" (ST 37) and "Zhongwan" (CV 12), with the ipsilateral "Tianshu" (ST 25) and "Shangjuxu" (ST 37) connected to the electrodes of the EA instrument, using disperse-dense wave, with a frequency of 10 Hz/50 Hz, and each intervention lasted for 20 minutes. Both interventions were performed once daily for 3 days. The general conditions of rats were observed daily. After intervention, the disease activity index (DAI) score was calculated; colon tissue morphology was observed using HE staining; serum levels of pro-inflammatory cytokines (interleukin [IL]-18, IL-1β) were measured by ELISA; protein expression of NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC), and Caspase-1 in colon tissues was detected by Western blot; positive expression of zonula occludens-1 (ZO-1) and Occludin in colon tissues was examined by immunofluorescence.

RESULTS

Compared with the blank group, the rats in the model group exhibited poor general conditions, slow body weight gain, shortened colon length (<0.01), increased DAI score and spleen index (<0.01), elevated serum IL-18 and IL-1β levels, and increased protein expression of NLRP3, ASC, and Caspase-1 in colon tissues (<0.01), along with decreased positive expression of ZO-1 and Occludin in colon tissues (<0.01). Compared with the model group, the rats in the medication group and the EA group exhibited improved general conditions, accelerated body weight gain, increased colon length (<0.05), reduced DAI scores and spleen indexes (<0.05), decreased serum IL-18 and IL-1β levels, and lower protein expression of NLRP3, ASC and Caspase-1 in colon tissues (<0.05), as well as increased positive expression of ZO-1 and Occludin in colon tissues (<0.05). There were no significant differences in the above indexes between the medication group and the EA group (>0.05). Compared with the blank group, the rats in the model group exhibited disrupted colon mucosal morphology, disordered gland arrangement, and atrophy of crypts, along with significant inflammatory cell infiltration. Compared with the model group, the rats in both the medication group and the EA group showed relatively intact colon mucosal morphology, with restored and improved gland and crypt structures, and reduced inflammatory cell infiltration.

CONCLUSIONS

EA with "intestinal disease prescription" has a significant therapeutic effect on DSS-induced UC, possibly by regulating the expression of NLRP3 inflammasome and proteins related to the intestinal mucosal barrier, thereby alleviating symptoms of ulcerative colitis.