Basic Study
Copyright ©The Author(s) 2019. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Aug 28, 2019; 25(32): 4696-4714
Published online Aug 28, 2019. doi: 10.3748/wjg.v25.i32.4696
Effect of mild moxibustion on intestinal microbiota and NLRP6 inflammasome signaling in rats with post-inflammatory irritable bowel syndrome
Chun-Hui Bao, Chun-Ye Wang, Guo-Na Li, Yi-Lu Yan, Di Wang, Xiao-Ming Jin, Lu-Yi Wu, Hui-Rong Liu, Xiao-Mei Wang, Zheng Shi, Huan-Gan Wu
Chun-Hui Bao, Chun-Ye Wang, Guo-Na Li, Yi-Lu Yan, Di Wang, Lu-Yi Wu, Hui-Rong Liu, Xiao-Mei Wang, Zheng Shi, Huan-Gan Wu, Key Laboratory of Acupuncture and Immunological Effects, Shanghai University of Traditional Chinese Medicine, Shanghai 200030, China
Xiao-Ming Jin, Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, United States
Author contributions: Bao CH and Wang CY contributed equally to this work; Wu HG and Bao CH conceived and designed this research; Bao CH and Wang CY wrote the manuscript; Li GN and Jin XM revised the manuscript; Bao CH, Wang CY, and Yan YL performed the experiments; Wu LY and Wang XM collected and analyzed the data; Li GN and Wang D prepared the figures and tables; Shi Z and Liu HR supervised the research; all authors approved the final version of this article.
Supported by the National Natural Science Foundation of China, No. 81503656; and the National Key Basic Research Program of China (973 Program), No. 2015CB554501 and No. 2009CB522900.
Institutional review board statement: The study was reviewed and approved by the standardizing laboratory animal ethical review of Shanghai University of Traditional Chinese Medicine.
Institutional animal care and use committee statement: All procedures involving animals were reviewed and approved by the standardizing laboratory animal ethical review of Shanghai University of Traditional Chinese Medicine (Ethical review code: SZY201711006).
Conflict-of-interest statement: The authors declare no conflict of interest related to this study.
Data sharing statement: No additional data are available.
ARRIVE guidelines statement: The ARRIVE guidelines have been adopted.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author: Huan-Gan Wu, PhD, Professor, Key Laboratory of Acupuncture and Immunological Effects, Shanghai University of Traditional Chinese Medicine, 650 South Wanping Road, Xuhui District, Shanghai 200030, China. wuhuangan@126.com
Telephone: +86-21-64644238 Fax: +86-21-64644238
Received: April 15, 2019
Peer-review started: April 15, 2019
First decision: June 16, 2019
Revised: June 27, 2019
Accepted: July 5, 2019
Article in press: July 5, 2019
Published online: August 28, 2019
Abstract
BACKGROUND

About one-third of refractory irritable bowel syndrome (IBS) cases are caused by gastrointestinal (GI) infection/inflammation, known as post-infectious/post-inflammatory IBS (PI-IBS). Although it is known that intestinal microbiota and host NOD-like receptor family pyrin domain containing 6 (NLRP6) inflammsome signaling are closely related to PI-IBS and moxibustion has a therapeutic effect on PI-IBS, whether moxibustion regulates the intestinal flora and host NLRP6 events in PI-IBS remains unclear.

AIM

To examine the regulatory effect of moxibustion on intestinal microbiota and host NLRP6 inflammatory signaling in PI-IBS.

METHODS

Sprague-Dawley rats were divided into a normal control group, a model control group, a mild moxibustion group, and a sham mild moxibustion group. PI-IBS rats in the mild moxibustion group were treated with moxibusiton at bilateral Tianshu (ST 25) and Zusanli (ST36) for 7 consecutive days for 10 min each time. The sham group rats were given the same treatment as the mild moxibustion group except the moxa stick was not ignited. Abdominal withdrawal reflex (AWR) score was measured to assess the visceral sensitivity, and colon histopathology and ultrastructure, colonic myeloperoxidase (MPO) activity, and serum C-reactive protein (CRP) level were measured to evaluate low-grade colonic inflammation in rats. The relative abundance of selected intestinal bacteria in rat feces was detected by 16S rDNA PCR and the NLRP6 inflammsome signaling in the colon was detected by immunofluorescence, qRT-PCR, and Western blot.

RESULTS

The AWR score was significantly decreased and the low-grade intestinal inflammation reflected by serum CRP and colonic MPO levels was inhibited in the mild moxibustion group compared with the sham group. Mild moxibustion remarkably increased the relative DNA abundances of Lactobacillus, Bifidobacterium, and Faecalibacterium prausnitzii but decreased that of Escherichia coli in the gut of PI-IBS rats. Additionally, mild moxibustion induced mRNA and protein expression of intestine lectin 1 but inhibited the expression of IL-1β, IL-18, and resistance-like molecule β by promoting the NLRP6 and reducing the mRNA and protein expression of apoptosis-associated speck-like protein containing CARD (ASC) and cysteinyl-aspartate-specific proteinase 1 (Caspase-1). The relative DNA abundances of Lactobacillus, Bifidobacteria, Faecalibacterium prausnitzii, and Escherichia coli in each group were correlated with the mRNA and protein expression of NLRP6, ASC, and Caspase-1 in the colon.

CONCLUSION

These findings indicated that mild moxibustion can relieve low-grade GI inflammation and alleviate visceral hypersensitivity in PI-IBS by regulating intestinal microbes and controlling NLRP6 inflammasome signaling.

Keywords: Moxibustion, Post-inflammation irritable bowel syndrome, Intestinal microbes, NLRP6 inflammasome, Intestinal inflammation, Visceral hypersensitivity, Traditional Chinese medicine

Core tip: Moxibustion has been shown to have a therapeutic effect on post-infectious/post-inflammatory irritable bowel syndrome (PI-IBS). However, it is unclear whether moxibustion achieves its therapeutic effect by regulating intestinal microbiota and inflammatory responses in PI-IBS. In this study, we found that visceral hypersensitivity and low-grade intestinal inflammation in PI-IBS rats were significantly inhibited by 7-d mild moxibustion treatment. This treatment effect of moxibustion may be related to regulating the relative abundances of selected gut microbes and controlling NLRP6 inflammasome signaling.