Case Control Study
Copyright ©The Author(s) 2022. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Clin Cases. Jul 6, 2022; 10(19): 6385-6398
Published online Jul 6, 2022. doi: 10.12998/wjcc.v10.i19.6385
Intestinal mucosal barrier in functional constipation: Dose it change?
Jun-Ke Wang, Wei Wei, Dong-Yan Zhao, Hui-Fen Wang, Yan-Li Zhang, Jie-Ping Lei, Shu-Kun Yao
Jun-Ke Wang, Dong-Yan Zhao, Shu-Kun Yao, Graduate School, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing 100730, China
Jun-Ke Wang, Dong-Yan Zhao, Hui-Fen Wang, Yan-Li Zhang, Shu-Kun Yao, Department of Gastroenterology, China-Japan Friendship Hospital, Beijing 100029, China
Wei Wei, Department of Clinical Nutrition and Department of Health Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing 100730, China
Jie-Ping Lei, Data and Project Management Unit, Institute of Clinical Medical Sciences, China-Japan Friendship Hospital, Beijing 100029, China
Author contributions: Wang JK designed and performed the study, analyzed the data, and drafted the manuscript; Wei W, Zhao DY, Wang HF, and Zhang YL collected the clinical data and samples from subjects; Lei JP contributed to the study design and data analysis; Yao SK designed the study, supervised the study performance, revised the manuscript, and obtained the funding; all authors read and approved the final manuscript.
Supported by the National Key Technology Support Program during “12th Five-Year Plan” Period of China, No. 2014BAI08B00; and the Project “The role of the gut microbiota and metabolites in the pathogenesis of diarrhea-predominant irritable bowel syndrome” of China-Japan Friendship Hospital, No. 2019-64-K44.
Institutional review board statement: The study was approved by the Ethics Committee of China-Japan Friendship Hospital (No. 2019-64-K44).
Informed consent statement: All study participants provided written informed consent prior to study enrollment.
Conflict-of-interest statement: All authors report no conflicts of interest.
Data sharing statement: No additional data are available.
STROBE statement: The authors have read the STROBE Statement-checklist of items, and the manuscript was prepared and revised according to the STROBE Statement-checklist of items.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (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: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Shu-Kun Yao, MD, PhD, Doctor, Professor, Graduate School, Peking Union Medical College and Chinese Academy of Medical Sciences; Department of Gastroenterology, China-Japan Friendship Hospital, No. 2 Yinghua East Road, Chaoyang District, Beijing 100029, China. shukunyao@126.com
Received: February 1, 2022
Peer-review started: February 1, 2022
First decision: March 15, 2022
Revised: March 21, 2022
Accepted: April 9, 2022
Article in press: April 9, 2022
Published online: July 6, 2022
Abstract
BACKGROUND

The intestinal mucosal barrier is the first line of defense against numerous harmful substances, and it contributes to the maintenance of intestinal homeostasis. Recent studies reported that structural and functional changes in the intestinal mucosal barrier were involved in the pathogenesis of several intestinal diseases. However, no study thoroughly evaluated this barrier in patients with functional constipation (FC).

AIM

To investigate the intestinal mucosal barrier in FC, including the mucus barrier, intercellular junctions, mucosal immunity and gut permeability.

METHODS

Forty FC patients who fulfilled the Rome IV criteria and 24 healthy controls were recruited in the Department of Gastroenterology of China-Japan Friendship Hospital. The colonic mucus barrier, intercellular junctions in the colonic epithelium, mucosal immune state and gut permeability in FC patients were comprehensively examined. Goblet cells were stained with Alcian Blue/Periodic acid Schiff (AB/PAS) and counted. The ultrastructure of intercellular junctional complexes was observed under an electron microscope. Occludin and zonula occludens-1 (ZO-1) in the colonic mucosa were located and quantified using immunohistochemistry and quantitative real-time polymerase chain reaction. Colonic CD3+ intraepithelial lymphocytes (IELs) and CD3+ lymphocytes in the lamina propria were identified and counted using immunofluorescence. The serum levels of D-lactic acid and zonulin were detected using enzyme-linked immunosorbent assay.

RESULTS

Compared to healthy controls, the staining of mucus secreted by goblet cells was darker in FC patients, and the number of goblet cells per upper crypt in the colonic mucosa was significantly increased in FC patients (control, 18.67 ± 2.99; FC, 22.42 ± 4.09; P = 0.001). The intercellular junctional complexes in the colonic epithelium were integral in FC patients. The distribution of mucosal occludin and ZO-1 was not altered in FC patients. No significant differences were found in occludin (control, 5.76E-2 ± 1.62E-2; FC, 5.17E-2 ± 1.80E-2; P = 0.240) and ZO-1 (control, 2.29E-2 ± 0.93E-2; FC, 2.68E-2 ± 1.60E-2; P = 0.333) protein expression between the two groups. The mRNA levels in occludin and ZO-1 were not modified in FC patients compared to healthy controls (P = 0.145, P = 0.451, respectively). No significant differences were observed in the number of CD3+ IELs per 100 epithelial cells (control, 5.62 ± 2.06; FC, 4.50 ± 2.16; P = 0.070) and CD3+ lamina propria lymphocytes (control, 19.69 ± 6.04/mm2; FC, 22.70 ± 11.38/mm2; P = 0.273). There were no significant differences in serum D-lactic acid [control, 5.21 (4.46, 5.49) mmol/L; FC, 4.63 (4.31, 5.42) mmol/L; P = 0.112] or zonulin [control, 1.36 (0.53, 2.15) ng/mL; FC, 0.94 (0.47, 1.56) ng/mL; P = 0.185] levels between FC patients and healthy controls.

CONCLUSION

The intestinal mucosal barrier in FC patients exhibits a compensatory increase in goblet cells and integral intercellular junctions without activation of mucosal immunity or increased gut permeability.

Keywords: Intestinal mucosal barrier, Functional constipation, Goblet cells, Intercellular junctions, Mucosal immunity, Gut permeability

Core Tip: The present study investigated the intestinal mucosal barrier in functional constipation (FC) patients for the first time, including the mucus barrier, the intestinal epithelial barrier, the mucosal immune state and gut permeability. FC patients exhibited a significant increase in goblet cells and integral intercellular junctional complexes. There were no significant alterations in the localization and expression of occludin and zonula occludens-1 in FC patients. No significant increase in CD3+ intraepithelial lymphocytes, CD3+ lamina propria lymphocytes, serum D-lactic acid or zonulin levels was found in FC patients, which indicated no mucosal immune activation or increased gut permeability.