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World J Gastroenterol. Aug 14, 2022; 28(30): 4053-4060
Published online Aug 14, 2022. doi: 10.3748/wjg.v28.i30.4053
Gut microbiota, inflammatory bowel disease and colorectal cancer
Ana Elisa Valencise Quaglio, Thais Gagno Grillo, Ellen Cristina Souza De Oliveira, Luiz Claudio Di Stasi, Ligia Yukie Sassaki
Ana Elisa Valencise Quaglio, Luiz Claudio Di Stasi, Departament of Biophysics and Pharmacology, São Paulo State University (Unesp), Institute of Biosciences, Botucatu 18618-689, São Paulo State, Brazil
Thais Gagno Grillo, Ellen Cristina Souza De Oliveira, Ligia Yukie Sassaki, Department of Internal Medicine, São Paulo State University (Unesp), Medical School, Botucatu 18618-686, São Paulo State, Brazil
Author contributions: Quaglio AEV, Grillo TG, and De Oliveira ECS performed the majority of the writing; Di Stasi LC and Sassaki LY designed the outline and coordinated the writing of the paper; all authors critically revised the manuscript for important intellectual content and approved the final version.
Conflict-of-interest statement: There are no conflicts of interest to report.
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 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: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Ligia Yukie Sassaki, MD, PhD, Assistant Professor, Ligia Yukie Sassaki, MD, PhD, Assistant Professor, Department of Internal Medicine, São Paulo State University (Unesp), Medical School, s/n. Bairro Rubião Junior, Botucatu 18618-686, São Paulo State, Brazil. ligia.sassaki@unesp.br
Received: January 18, 2022
Peer-review started: January 18, 2022
First decision: March 8, 2022
Revised: March 16, 2022
Accepted: July 18, 2022
Article in press: July 18, 2022
Published online: August 14, 2022
Abstract

The gut microbiota is a complex community of microorganisms that inhabit the digestive tracts of humans, living in symbiosis with the host. Dysbiosis, characterized by an imbalance between the beneficial and opportunistic gut microbiota, is associated with several gastrointestinal disorders, such as irritable bowel syndrome (IBS); inflammatory bowel disease (IBD), represented by ulcerative colitis and Crohn’s disease; and colorectal cancer (CRC). Dysbiosis can disrupt the mucosal barrier, resulting in perpetuation of inflammation and carcinogenesis. The increase in some specific groups of harmful bacteria, such as Escherichia coli (E. coli) and enterotoxigenic Bacteroides fragilis (ETBF), has been associated with chronic tissue inflammation and the release of pro-inflammatory and carcinogenic mediators, increasing the chance of developing CRC, following the inflammation-dysplasia-cancer sequence in IBD patients. Therefore, the aim of the present review was to analyze the correlation between changes in the gut microbiota and the development and maintenance of IBD, CRC, and IBD-associated CRC. Patients with IBD and CRC have shown reduced bacterial diversity and abundance compared to healthy individuals, with enrichment of Firmicute sand Bacteroidetes. Specific bacteria are also associated with the onset and progression of CRC, such as Fusobacterium nucleatum, E. coli, Enterococcus faecalis, Streptococcus gallolyticus, and ETBF. Future research can evaluate the advantages of modulating the gut microbiota as preventive measures in CRC high-risk patients, directly affecting the prognosis of the disease and the quality of life of patients.

Keywords: Gut microbiota, Dysbiosis, Ulcerative colitis, Crohn’s disease, Inflammatory bowel disease, Colorectal cancer

Core Tip: Dysbiosis is present in patients with inflammatory bowel disease (IBD) and colorectal cancer (CRC). Dysbiosis can lead to a disruption of the mucosal barrier of the digestive tract lining, resulting in the perpetuation of inflammation and carcinogenesis, thus increasing the risk of developing CRC in IBD patients. Therefore, the aim of this review was to analyze the correlation between changes in gut microbiota and the development of IBD, CRC, and IBD-associated CRC. Further studies should be carried out to identify bacterial species that cause imbalances in the gut microbiota, enabling the development of prevention strategies or treatment of IBD-associated CRC.