Myocyte Specific Upregulation of ACE2 in Cardiovascular Disease: Implications for SARS-CoV-2 mediated myocarditis

Nathan R Tucker; Mark Chaffin; Kenneth C Bedi; Irinna Papangeli; Amer-Denis Akkad; Alessandro Arduini; Sikander Hayat; Gökcen Eraslan; Christoph Muus; Roby Bhattacharyya; Christian M Stegmann; Kenneth B Margulies; Patrick T Ellinor

ACE2 expression in the heart is strongest in pericytes, which line the microvasculature, but is also appreciable in vascular smooth muscle cells, fibroblasts and cardiomyocytes (Fig. 1a) . We also evaluated the expression of the proteases encoded by TMPRSS2 and CTSL, which facilitate membrane fusion and viral uptake during SARS-CoV-2 infection. 1, 9 TMPRSS2 was minimally expressed across all cell types, while CTSL displayed low levels of expression in all cell types with strongest expression in fibroblasts (18.1% and 56.7% of cells in the two populations found in non-failing controls), macrophages (39.1%), adipocytes (41.5%), and cardiomyocytes (11.4%) (Supplementary Fig. 1) . These results are in concordance with recently released single nuclei data from Chen et al. 10 Analyses of previously generated bulk RNA-seq data from these individuals show no significant alterations in ACE2 expression in the context of dilated or hypertrophic cardiomyopathy compared to non-failing controls (Fig. 1b) . However, single nucleus RNA-seq highlighted a stark downregulation of ACE2 expression in fibroblasts, pericytes, and vascular smooth muscle. There was a concomitant upregulation in ACE2 expression in cardiomyocytes in DCM and HCM (Fig. 1c) . The complete cell subtype differential expression analysis of ACE2 in DCM and HCM compared to non-failing controls is provided in Supplementary Tables 2 and 3 , respectively. A sensitivity analysis comparing the expression of ACE2 in left ventricles samples from individuals with hypertrophic cardiomyopathy compared to non-failing controls after exclusion of individuals on ACE inhibitors or ARBs is provided in Supplementary Table 4 .