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Copyright ©The Author(s) 2022. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jul 7, 2022; 28(25): 2802-2822
Published online Jul 7, 2022. doi: 10.3748/wjg.v28.i25.2802
Altered gut microbiota patterns in COVID-19: Markers for inflammation and disease severity
Chiranjib Chakraborty, Ashish Ranjan Sharma, Manojit Bhattacharya, Kuldeep Dhama, Sang-Soo Lee
Chiranjib Chakraborty, School of Life Science and Biotechnology, Adamas University, Kolkata 700126, India
Ashish Ranjan Sharma, Institute for Skeletal Aging & Orthopaedic Surgery, Hallym University, Chuncheon-si 24252, South Korea
Manojit Bhattacharya, Department of Zoology, Fakir Mohan University, Balasore 756020, India
Kuldeep Dhama, Division of Pathology, Indian Council of Agricultural Research (ICAR)-Indian Veterinary Research Institute (IVRI), Bareilly 243122, Uttar Pradesh, India
Sang-Soo Lee, Institute for Skeletal Aging & Orthopedic Surgery, Hallym University, Chuncheon-si 24252, South Korea
Author contributions: Chakraborty C, Sharma AR, and Bhattacharya M contributed equally, Chakraborty C designed the research study and wrote the main manuscript draft; Sharma AR reviewed and edited the manuscript; Bhattacharya M developed the figures and tables; Dhama KD performed the English editing and validation; Lee SS did the funding acquisition; all authors have read and approved the final manuscript.
Supported by the Hallym University Research Fund and the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2020R1C1C1008694 & NRF-2020R1I1A3074575).
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: Sang-Soo Lee, MD, PhD, Full Professor, Institute for Skeletal Aging & Orthopedic Surgery, Hallym University, Chuncheon-si 24252, South Korea. 123sslee@gmail.com
Received: January 12, 2022
Peer-review started: January 12, 2022
First decision: March 10, 2022
Revised: March 19, 2022
Accepted: May 13, 2022
Article in press: May 13, 2022
Published online: July 7, 2022
Processing time: 173 Days and 6.2 Hours
Abstract

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection leads to a severe respiratory illness and alters the gut microbiota, which dynamically interacts with the human immune system. Microbiota alterations include decreased levels of beneficial bacteria and augmentation of opportunistic pathogens. Here, we describe critical factors affecting the microbiota in coronavirus disease 2019 (COVID-19) patients. These include, such as gut microbiota imbalance and gastrointestinal symptoms, the pattern of altered gut microbiota composition in COVID-19 patients, and crosstalk between the microbiome and the gut-lung axis/gut-brain-lung axis. Moreover, we have illustrated the hypoxia state in COVID-19 associated gut microbiota alteration. The role of ACE2 in the digestive system, and control of its expression using the gut microbiota is discussed, highlighting the interactions between the lungs, the gut, and the brain during COVID-19 infection. Similarly, we address the gut microbiota in elderly or co-morbid patients as well as gut microbiota dysbiosis of in severe COVID-19. Several clinical trials to understand the role of probiotics in COVID-19 patients are listed in this review. Augmented inflammation is one of the major driving forces for COVID-19 symptoms and gut microbiome disruption and is associated with disease severity. However, understanding the role of the gut microbiota in immune modulation during SARS-CoV-2 infection may help improve therapeutic strategies for COVID-19 treatment.

Keywords: COVID-19; Inflammation; Gut microbiota; Therapeutic

Core Tip: The gut microbiota of coronavirus disease 2019 (COVID-19) patients is altered compared to that of healthy individuals, with a reduction in the count of beneficial bacteria and an increase in the count of opportunistic fungi. In this review, we elucidate the components governing immune modulation. Additionally, we explore the effect of changes in the microbial ecosystem in COVID-19 patients, with an aim to help develop precise therapeutics and expand our knowledge regarding the pattern of changes in the gut microbiota of COVID-19 patients.