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World J Clin Cases. Jun 16, 2021; 9(17): 4133-4142
Published online Jun 16, 2021. doi: 10.12998/wjcc.v9.i17.4133
Nonalcoholic fatty liver disease and COVID-19: An epidemic that begets pandemic
Musaab Ahmed, Mohamed H Ahmed
Musaab Ahmed, College of Medicine, Ajman University, Ajman 346, United Arab Emirates
Mohamed H Ahmed, Department of Medicine and HIV Metabolic Clinic, Milton Keynes University Hospital NHS Foundation Trust, Milton Keynes MK5 6LD, United Kingdom
Author contributions: Ahmed M and Ahmed MH contributed equally to manuscript preparation and writing, and performance of the analysis with constructive discussions; Ahmed MH designed the outline of the review.
Conflict-of-interest statement: The authors declare no conflict of interest related to this manuscript.
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: http://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Mohamed H Ahmed, MBBS, PhD, Doctor, Department of Medicine and HIV Metabolic Clinic, Milton Keynes University Hospital NHS Foundation Trust, Eaglestone, Milton Keynes MK5 6LD, United Kingdom. mohamed.hassan-ahmed@mkuh.nhs.uk
Received: January 13, 2021
Peer-review started: January 13, 2021
First decision: February 10, 2021
Revised: February 24, 2021
Accepted: April 26, 2021
Article in press: April 26, 2021
Published online: June 16, 2021
Abstract

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a global pandemic, affecting all the individuals across the planet. COVID-19 has gained significant attention due to its high prevalence among individuals with diabetes, nonalcoholic fatty liver disease (NAFLD), and metabolic syndrome. NAFLD is the hepatic manifestation of metabolic syndrome and can be associated with a high risk of developing type 2 diabetes. The association of COVID-19 and NAFLD has also gained more attention because NAFLD is highly associated with the epidemic of obesity. NAFLD is a potential risk factor for SARS-CoV-2 infection and severe COVID-19, independent of metabolic syndrome. Importantly, it is not yet clear whether the epidemics of obesity and NAFLD have perpetuated the current pandemic of COVID-19. Further research is urgently needed to assess the following: (1) Whether NAFLD is a high risk factor for SARS-CoV-2 infection; (2) Whether NAFLD is associated with the severe form of COVID-19; and (3) Whether the presence of NAFLD can explain the racial variation in the morbidity and mortality associated with COVID-19. This review summarizes the interactions between COVID-19 and NAFLD, mechanism of liver injury by COVID-19, and effect of lockdown due to COVID- 19 on patients with NAFLD.

Keywords: Fatty liver, COVID-19, Diabetes, Obesity, Pandemic

Core Tip: Earlier studies suggested that individuals most vulnerable to severe acute respiratory syndrome coronavirus 2 infection suffer from pre-existing disease, including nonalcoholic fatty liver disease (NAFLD). There is an interwoven relationship between NAFLD and the associated high-risk factors for coronavirus disease 2019 (COVID-19). NAFLD can increase risk of infection, lung injury, cardiac impairment, and difficulty with respiratory ventilation, and can be associated with higher risk for COVID-19, especially in the presence of liver fibrosis. The association between high production of interleukin-6 in both NAFLD and COVID-19 merits further research to determine whether NAFLD is directly involved in the cytokine storms.