Abstract MP62: Sars-cov-2 Spike Protein Regulation Of Angiotensin Converting Enzyme 2 And Tissue Renin-angiotensin Systems: Influence Of Biologic Sex

Abstract

Angiotensin converting enzyme 2 (ACE2), the SARS-CoV-2 receptor and an enzyme of the renin-angiotensin system (RAS), is on the X chromosome and stimulated by estrogen. Male sex is a risk factor for SARS-CoV-2 severity. Previous investigators demonstrated that the SARs-CoV-2 Spike (S) protein decreases tissue ACE2 by protein internalization or shedding. This study defined sex differences in tissue ACE2 expression and their impact on SARS-CoV-2 S protein regulation of ACE2 activity and AngII levels. Male and female intact or gonadectomized (GDX) low density lipoprotein receptor deficient ( Ldlr -/- ) mice, and Four Core Genotype (FCG) male (XY or XX) or female (XX or XY) mice were fed a Western diet for 4 months. In lung, ACE2 mRNA abundance was similar in male and female mice and reduced by GDX (Male XY intact: 1.04 ± 0.15; Female XX intact: 1.13 ± 0.13; Male XY GDX: 0.11 ± 0.03; Female XX GDX: 0.18 ± 0.04 ΔΔCt; P<0.05). Lungs from XX mice had higher ACE2 mRNA abundance than XY mice regardless of gonadal sex (P<0.05), and GDX reduced ACE2 mRNA abundance in lungs of XX, but not XY females (XX Female GDX: 0.18 ± 0.04; XY Female GDX: 0.38 ± 0.09; P<0.05). In adipose, XX females had higher ACE2 mRNA abundance than XY males (XX female: 5.4 ± 0.7; XY male: 1.0 ± 0.1; P<0.05), regardless of gonadal sex (XY females: 3.3 ± 0.7; XX males: 1.5 ± 0.3; P<0.05). Male XY and female XX Ldlr -/- mice were administered vehicle or SARS-CoV-2 S protein (2 nmol/kg, ip, 3 doses) with tissue harvest six hours later. In lung, AngII levels were increased by S protein in male, but not female mice (Male, vehicle: 12.3 ± 2.3; Male, S protein: 33.6 ± 7.1; Female, vehicle: 16.1 ± 2.0; Female, S protein: 20.2 ± 1.3 pg/μg protein; P<0.05). In adipose, ACE2 activity was reduced by S protein in male, but not female mice (Male, vehicle: 63.6 ± 13.9; Male, S protein: 26.1 ± 1.9; Female, vehicle: 32.5 ± 1.9; Female, S protein: 25.1 ± 1.3 RFU/hr/mg tissue; P<0.05). SARS-CoV-2 S protein (35 nM) decreased ACE2 activity in type II lung alveolar cells (Vehicle: 2.0 x 10 4 ; S protein: 1.2 x 10 4 RFU/10 6 cells) and 3T3-L1 adipocytes (Vehicle: 2.1 x 10 4 ± 0.3 x 10 4 ; S protein: 1.1 x 10 4 ± 0.8 x 10 3 RFU/10 5 cells; P<0.05). Biologic sex regulation of ACE2 may protect females from SARS-CoV-2 S protein-mediated ACE2 reductions and activation of the local RAS.