Copyright ©The Author(s) 2021. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. May 28, 2021; 27(20): 2576-2585
Published online May 28, 2021. doi: 10.3748/wjg.v27.i20.2576
COVID-19 in normal, diseased and transplanted liver
Alessandro Signorello, Ilaria Lenci, Martina Milana, Giuseppe Grassi, Leonardo Baiocchi
Alessandro Signorello, Ilaria Lenci, Martina Milana, Giuseppe Grassi, Leonardo Baiocchi, Hepatology Unit, Department of Medicine, University of Tor Vergata, Rome 00133, Italy
Author contributions: Signorello A performed acquisition of data, analysis and interpretation, drafting of manuscript, critical revision; Lenci I, Milana M, and Grassi G performed acquisition of data, critical revision; Baiocchi L performed proposal of study, study conception, correction of manuscript, critical revision.
Conflict-of-interest statement: No conflict of interest to disclose.
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:
Corresponding author: Leonardo Baiocchi, MD, PhD, Associate Professor, Hepatology Unit, Department of Medicine, University of Tor Vergata, Viale Oxford 81, Rome 00133, Italy.
Received: February 18, 2021
Peer-review started: February 18, 2021
First decision: March 12, 2021
Revised: March 18, 2021
Accepted: May 7, 2021
Article in press: May 7, 2021
Published online: May 28, 2021

Starting from December 2019 the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has extended in the entire world giving origin to a pandemic. Although the respiratory system is the main apparatus involved by the infection, several other organs may suffer coronavirus disease 2019 (COVID-19)-related injuries. The human tissues expressing angiotensin-converting enzyme 2 (ACE2) are all possible targets of viral damage. In fact myocarditis, meningo-encephalitis, acute kidney injury and other complications have been described with regard to SARS-CoV-2 infection. The liver has a central role in the body homeostasis contributing to detoxification, catabolism and also synthesis of important factor such as plasma proteins. ACE2 is significantly expressed just by cholangiocytes within the liver, however transaminases are increased in more than one third of COVID-19 patients, at hospital admission. The reasons for liver impairment in the course of this infection are not completely clear at present and multiple factors such as: Direct viral effect, release of cytokines, ischemic damage, use of hepatotoxic drugs, sepsis, and others, may contribute to damage. While COVID-19 seems to elicit just a transient alteration of liver function tests in subjects with normal hepatic function, of concern, more severe sequelae are frequently observed in patients with a reduced hepatic reserve. In this review we report data regarding SARS-CoV-2 infection in subjects with normal or diseased liver. In addition the risks of COVID-19 in immunosuppressed patients (either transplanted or suffering for autoimmune liver diseases) are also described.

Keywords: COVID-19, Liver, Non-alcoholic fatty-liver-disease, Cirrhosis, Liver transplant, Angiotensin-converting enzyme 2

Core Tip: Severe acute respiratory syndrome coronavirus 2 infection, starting from December 2019 in China, has now extended in the whole world. While the respiratory system is mainly involved in the infection other organs may be impaired by coronavirus disease 2019 (COVID-19). In this review we report the current finding regarding the liver during this infection. While mild liver effects occur in normal subjects with COVID-19, severe sequelae may be expected in individuals with a reduced hepatic reserve.