key: cord-1010772-vz3fwhbd
authors: Meijnikman, Abraham S.; Bruin, Sjoerd; Groen, Albert K.; Nieuwdorp, Max; Herrema, Hilde
title: Increased expression of key SARS-CoV-2 entry points in multiple tissues in individuals with NAFLD
date: 2020-12-16
journal: J Hepatol
DOI: 10.1016/j.jhep.2020.12.007
sha: f643bb0ca43983688a4fccb8cc7d3587012e86fe
doc_id: 1010772
cord_uid: vz3fwhbd

nan

Recently, Fondevila and colleagues [1] reported that individuals with Non-Alcoholic Steatohepatitis (NASH), one of the more severe manifestations of Non-Alcoholic Fatty Liver Disease (NAFLD), have increased hepatic expression of key entry points of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Increased hepatic expression of the SARS-CoV-2 entry points angiotensin converting enzyme 2 (ACE2) and transmembrane protease serine 2 (TMPRSS2) in individuals with NAFLD, possibly provides a mechanistic explanation for increased susceptibility to hepatic complications in this population. These findings are of relevance for the ongoing coronavirus disease 2019 (COVID-19) global health crisis, which affects in particular those with underlying health conditions including NAFLD [2] [3] [4] . Given the multifactorial and multiorgan nature of NAFLD, we here address multi-organ expression of SARS-CoV-2 entry points in tightly matched obese individuals with and without NAFLD.

To assess multi-organ expression of SARS-CoV-2-entry points in NAFLD, we included 56 women from our bariatric surgery cohort [5] of whom RNA transcriptomic data was available from liver, jejunum, visceral (VAT) and subcutaneous adipose tissue (SAT). Prior to surgery, every individual underwent a complete metabolic work-up (Supplemental Table 1 ) including a two-hour mixed meal tolerance test (MMT) to assess insulin resistance. In total, 23 individuals fulfilled the criteria for NAFLD (biopsy-proven) whereas 33 individuals did not.

NAFLD ranged from grade 1 to grade 2 steatosis. Of note, none of the included individuals had hepatocyte ballooning, a prerequisite for NASH diagnosis according to the Steatosis Activity and Fibrosis (SAF) criteria. From the extensive list of baseline characteristics, only alanine aminotransferase was significantly higher in individuals with NAFLD. Moreover, insulin and glucose excursions during the MMT did not differ between groups ( Figure 1A and 1B). We hence have a very homogenous study population that differ only in presence or absence of NAFLD. ACE2 expression was significantly higher in SAT, VAT and liver of individuals with NAFLD (Figure C-E) but did not reach significance in jejunal tissue ( Figure   1F ). Next, we addressed expression of the proteases, TMPRSS2, TMPRSS4 and Furin that assist ACE2-dependent cell entry of Sars-CoV-2. Although TMPRSS2 appeared higher in VAT and liver of individuals with NAFLD, expression levels did not reach significance J o u r n a l P r e -p r o o f ( Figure H,I) . In all tissues, TMPRSS2 and ACE2 correlated strong with each other. TMPRSS4

and Furin did not differ in the tissues analyzed (data not shown).

Since metabolic dysregulation has shown to be an independent predictor of death and morbidity in previous infectious epidemics [6] , we investigated the correlation between SARS-CoV-2-entry points and components of insulin resistance. Interestingly, liver ACE2 expression significantly correlated with insulin area under the curve (AUC) but not with glucose AUC determined during the MMT.

In conclusion, we report that ACE2 is upregulated in SAT, VAT and liver tissue of individuals with NAFLD. A presumably greater availability of ACE2 and the strong correlation with TMPRSS2 in these organs likely fosters viral penetration into cells. These results strengthen the link between NAFLD and severe COVID-19 independent of obesity.

Moreover, the strong correlation between insulin AUC and ACE2 in the liver might explain adverse clinical outcomes and laboratory results in SARS-CoV-2-infected individuals with T2D on insulin compared to those on metformin [7] . We thus presumably identified an additional mechanism that contributes to increased susceptibility for severe COVID-19 in individuals with NAFLD and individuals with insulin resistance or T2D. Last but not least, we underscore once more that "simple steatosis" is not as benign as sometimes assumed. Our results strengthen the need to develop accurate, non-invasive diagnostic methods for the early detection of NAFLD and subsequent COVID-19 risk identification.

J o u r n a l P r e -p r o o f 

Obese patients with NASH have increased hepatic expression of SARS-CoV-2 critical entry points

Non-alcoholic fatty liver diseases in patients with COVID-19: A retrospective study

Metabolicassociated fatty liver disease is associated with severity of COVID-19

Younger patients with MAFLD are at increased risk of severe COVID-19 illness: A multicenter preliminary analysis

A Systems Biology approach to understand gut microbiota and host metabolism in morbid obesity: design of the BARIA Longitudinal Cohort Study

COVID-19 in people with diabetes: understanding the reasons for worse outcomes

Clinical Characteristics and Outcomes of Patients with Diabetes and COVID-19 in Association with Glucose-Lowering Medication