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
Processing time: 136 Days and 2.8 Hours
ARTICLE HIGHLIGHTS
Research background

Irritable bowel syndrome (IBS) is a common functional gastrointestinal (GI) disorder with associated symptoms of abdominal pain and distention, dysphoria, and/or changes of defecation shape. About one-third of refractory IBS cases are caused by GI infection/inflammation, known as post-infectious/post-inflammatory IBS (PI-IBS). Moxibustion has been shown to have a therapeutic effect on PI-IBS but whether moxibustion achieves its therapeutic effect by regulating the intestinal microbiota and host NLRP6 inflammatory signaling in PI-IBS remains unclear. Our previous study found that moxibustion decreased gut relative DNA abundances of Prevotella, Bacteroides, and Clostridium XI, increased the abundances of Lactobacillus and Clostridium XIVa, and improved the gut microbiota alpha diversity in a chronic visceral pain model of IBS in rats.

Research motivation

The hypothesis behind this study is that moxibustion could relieve the low-grade GI inflammation and alleviate visceral hypersensitivity of PI-IBS by regulating intestinal microbes and controlling NLRP6 inflammasome signaling.

Research objectives

The aim of this study was to investigate the possible events behind the therapeutic effect of moxibustion on PI-IBS rats via regulating gut microbiota and NLRP6 inflammasome signaling.

Research methods

Sixty 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 given 7 d of continuous moxibustion treatment. The sham group was given the same treatment as the mild moxibustion group except the moxa stick was not ignited. PI-IBS was induced with TNBS in rats. Moxibustion was applied to the bilateral Zusanli (ST36) and Tianshu (ST25). The abdominal withdrawal reflex (AWR) scores were assessed under the induction of balloon dilation for colorectal distension. Haematoxylin and eosin staining was assessed to evaluate the changes in the colonic histopathology. Serum C-reactive protein (CRP) levels and colonic myeloperoxidase (MPO) activities in colonic tissues of rats were measured by ELISA. 16S rDNA PCR was applied for testing the DNA relative abundance of selected intestinal bacteria. Western blot and qPCR were used to determine the protein and mRNA expression of NLRP6, ASC, Caspase-1, IL-1β, IL-18, ITLN1, and RELMβ.

Research results

Compared with the normal control group, the PI-IBS model control group had higher AWR scores, serum CRP levels, and colonic MPO activities. After treatment, the scores were decreased in the moxibustion group compared with the model control group. Mild moxibustion significantly increased the relative DNA abundances of intestinal Lactobacillus, Bifidobacterium, and Faecalibacterium prausnitzii but reduced the relative abundance of Escherichia coli in the gut of PI-IBS rats. Besides, mild moxibustion significantly enhanced the protein expression of NLRP6 and ITLN1 and inhibited the mRNA and protein expression of ASC, Caspase-1, IL-1β, IL-18, and RELMβ.

Research conclusions

This study revealed that mild moxibustion inhibits intestinal low-grade inflammation via regulating DNA abundances of gut microbes and NLRP6 inflammasome signaling, which may be an important mechanism of mild moxibustion in relieving visceral hypersensitivity in PI-IBS.

Research perspectives

Our findings may provide an experimental and scientific basis for the effective treatment of PI-IBS by mild moxibustion.