774 THE PROGNOSTIC ROLE OF GENOTYPIC VARIANTS OF ACE2 AND TMPRSS2 POLYMORPHISMS IN SARS-COV2 / COVID-19 INFECTION
Authors: Fioretti Francesco , Praderio Angelica , Sammartino Antonio , De Angelis Maria Grazia , Ravasio Francesco , Inciardi Riccardo Maria , Nodari Savina 
Published: December 2022

Abstract

Background
to date, more than 243 million COVID-19 cases have been diagnosed globally, with 4.94 million deaths, 489.000 new cases and 8.474 deaths per day. In Italy there are currently 4.73 million cases and 132.000 deaths. It is well known that the entry of the SARS- CoV-2 virus into cells is mediated by the binding between the virus Spike-glycoprotein (S) and the membrane ACE2-receptor (ACE2-R). When SARS-CoV-2 binds to ACE2-R, with subsequent membrane fusion and virus entry into the cell, a down-regulation of these receptors occurs. ACE2 –R downregulation plays a crucial role in the pulmonary and systemic inflammatory response. A serious clinical course appears to be associated with some factors such as age, previous pathologies and comorbidities. However, also a dysregulation of the RAA system linked to a different expression of ACE-2 R and TMPRSS2 gene polymorphisms and different serum levels of soluble ACE2 (sACE2), could be associated with abnormal inflammatory and immune response to SARS-CoV-2 infection.

Aim of the Study
we aimed to verify whether there is an association between the clinical course of COVID-19 patients (pts) and the presence of more frequent ACE2 and TMPRSS2 single-nucleotide polymorphisms (SNPs) and if sACE2 levels are related to specific ACE2 and TMPRSS2 polymorphic variants.

Methods
we consecutively enrolled subjects with previous documented SARS-CoV-2 infection and divided our sample into three groups: pts with asymptomatic course; pts with symptomatic course but without the need for hospitalization for COVID-19; pts with severe symptomatic course requiring hospitalization in intensive care unit. Data about age, clinical course, comorbidities, and therapies were collected. Blood samples were taken for the genetic analysis of the most frequent SNPs of the ACE2-R and TMPRSS2 detected in Italian population, in particular genotypic variants TT and CC of ACE2 SNPs 1 and 5 (rate of 5% and 14% respectively) and genotypic variants TT and CC of TMPRSS2 SNPs 2 and 3 (rate of 50% and 30% respective).

Results
among 178 pts enrolled up to March 2022, we have so far analyzed the genetic polymorphisms of 74 pts.; 21 (28%) were hospitalized for COVID-19, 38 (51%) had symptomatic course without hospitalization and 15 (21%) were completely pauci-asymptomatics. Serum concentrations of sACE2 and distribution of polymorphic variants in the three groups are summarized in Table 1. We found that sACE2 levels were higher in genotypic variant CC of SNP 1 of TMPRSS2 gene (Table 2). Considering that a high concentration of sACE2 outlines a proinflammatory condition, it could be hypothesized that the CC genotype may be a predisposing condition to the cytokine storm of COVID-19.
Perspectives: Genetic analysis of ACE2 and TMPRSS2 SNPs will help to clarify the relationship between these polymorphic variant, sACE2 levels, risk of SARS-CoV2 infection and severity of clinical presentation of COVID-19 in patients with or without CV diseases.