[Effects of moxibustion at "Tianshu"（ST25） and "Shangjuxu" （ST37） on colonic metabolites and inflammatory factors in rats with Crohn's disease].

Objective: To observe the effects of moxibustion at "Tianshu"（ST25） and "Shangjuxu"（ST37） on the colonic metabolites and inflammatory factors in rats with Crohn's disease（CD）, so as to explore the mechanisms of moxibustion in protecting colon of CD rats based on metabolomics.

Methods: Twelve rats were first randomly selected from 36 male SD rats as a normal group（NG）. The CD model was induced by 2, 4, 6 trinitrobenzene sulfonic acid（TNBS） enema on the rest 24 rats. After successful modeling, rats were randomly divided into model（TNBS） and moxibustion（TNBS+MOX） groups（n=10 rats/group）. Moxibustion was applied at bilateral ST25 and ST37 for 30 min, once daily for 7 consecutive days in the TNBS+MOX group, while rats in the NG and TNBS groups did not receive any interventions. Body weight of rats was recorded and disease activity index（DAI） was assessed during the experiment. After interventions, HE staining was performed to observe pathological damage of colon. Serum levels of inflammatory factors were measured by ELISA. NMR hydrogen spectroscopy was used to detect colonic metabolites of each group, and orthogonal partial least squares discriminant analysis（OPLS-DA） was used to screen differential colonic metabolites between groups, followed by pathway analysis using MetaboAnalyst 5.0 platform.

Results: After modeling, compared with the NG group, the body weight of the rats in the TNBS group was significantly decreased（P<0.05）, the DAI score was increased （P<0.05）, the colon had obvious inflammatory damage and the pathological injury index was increased（P<0.05）, and levels of serum tumor necrosis factor-α（TNF-α）, interleukin（IL）-1β and interferon-γ（IFN-γ） were significantly increased（P<0.05）. After moxibustion intervention, compared with the TNBS group, the body weight was significantly increased（P<0.05）, while the levels of serum TNF-α, IL-1β, IFN-γ, and DAI score of the rats in the TNBS+MOX group were significantly decreased（P<0.05）, with alleviated colonic inflammatory injury detected by HE staining. Compared with the NG group, the relative expressions of colonic hypoxanthine, betaine, creatine, inositol, taurine, uracil, and methanol of the TNBS group were decreased（P<0.05）, while the relative expressions of histidine, leucine, proline, lysine, isoleucine, phenylalanine, tyrosine, propionic acid, and valine were increased（P<0.05） in the TNBS group, among which, relative expressions of hypoxanthine, leucine, lysine, isoleucine, betaine, tyrosine, and taurine were reversed in the TNBS+MOX group relevant to the TNBS group, mainly involving phenylalanine, tyrosine and tryptophan biosynthesis, and taurine and subtaurine metabolism pathway.

Conclusion: The mechanism of moxibustion at ST25 and ST37 for CD may be related to improving colon metabolic disorder state by regulating multiple metabolic metabolites and metabolic pathways, and reducing the level of inflammatory factors, so as to maintain intestinal immune homeostasis.