Single-cell RNA analysis on ACE2 expression provides insights into SARS-CoV-2 potential entry into the bloodstream and heart injury

Abstract

Coronavirus disease-2019 (COVID-19) is a global pandemic with high infectivity and pathogenicity, accounting for tens of thousands of deaths worldwide. Recent studies have found that the pathogen of COVID-19, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), shares the same cell receptor angiotensin converting enzyme II (ACE2) as SARS-CoV. The pathological investigation of COVID-19 deaths showed that the lungs had characteristics of pulmonary fibrosis. However, how SARS-CoV-2 spreads from the lungs to other organs has not yet been determined. Here, we performed an unbiased evaluation of cell-type-specific expression of ACE2 in healthy and fibrotic lungs, as well as in normal and failed adult human hearts, using published single-cell RNA-seq data. We found that ACE2 expression in fibrotic lungs mainly locates in arterial vascular cells, which might provide a route for bloodstream spreading of SARS-CoV-2. Failed human hearts have a higher percentage of ACE2-expressing cardiomyocytes, and SARS-CoV-2 might attack cardiomyocytes through the bloodstream in patients with heart failure. Moreover, ACE2 was highly expressed in cells infected by respiratory syncytial virus or Middle East respiratory syndrome coronavirus and in mice treated by lipopolysaccharide. Our findings indicate that patients with pulmonary fibrosis, heart failure, and virus infection have a higher risk and are more susceptible to SARS-CoV-2 infection. The SARS-CoV-2 might attack other organs by getting into the bloodstream. This study provides new insights into SARS-CoV-2 blood entry and heart injury and might propose a therapeutic strategy to prevent patients from developing severe complications.

Keywords: ACE2; COVID-19; SARS-CoV2; heart failure; pulmonary fibrosis.

Figure 1

Different distribution pattern of angiotensin converting enzyme II (ACE2)‐expressing cells in normal and fibrotic lungs. (a and b) Feature plot showing the distribution of ACE2, SFTPC, and GJA4 expression levels in normal lungs (a) and in fibrotic lungs (b). (c and d) Violin plot showing the distribution of ACE2, SFTPC, and GJA4 expression levels in normal lungs (c) and in fibrotic lungs (d)

Figure 2

Distribution of chemokine and proteases in normal and fibrotic lungs. (a,b) Feature plot showing the distribution of ACE2, CCL2, CXCL12, C1R, TMPRSS2, and FURIN expression levels in normal lungs (a) and in fibrotic lungs (b)

Figure 3

Different distribution of angiotensin converting enzyme II (ACE2)‐expressing cells in normal and failed hearts. (a,b) Feature plot showing the distribution of ACE2, GJA4, and MYH6 expression levels in normal hearts (a) and in failed hearts (b). (c) Immunofluorescence staining of ACE2 (red) expression and DAPI, 4',6‐diamidino‐2‐phenylindole (DAPI) (blue) in normal hearts, and in failed hearts. Scale bar = 20 μm (n = 4). Significance is determined with a two‐tailed unpaired Student's t test, **p < .01

Figure 4

Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analysis of artery vascular cells in normal hearts. (a) GO term (biological process) analysis of enriched Marker genes of cluster 7. (b) KEGG pathway analysis of enriched Marker genes of cluster 7. (c) Feature plot showing the distribution of expression levels of ACE2, CCL2, CXCL12, IGFBP7, ITGA7, ITGA1, FN1, and CD9 in normal hearts

Figure 5

Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analysis of artery vascular cells in failed hearts. (a) GO term (biological process) analysis of enriched Marker genes of cluster 5. (b) KEGG pathway analysis of enriched marker genes of cluster 5. (c) Feature plot showing the distribution of expression levels of ACE2, CD36, CD9, ITGA1, ITGA7, CCL2, CXCL12, SOX4, and MEF2C in failed hearts

Figure 6

Expression of angiotensin converting enzyme II (ACE2) under other infections. (a) Expression of ACE2 in H929 cells treated with mock virus or respiratory syncytial virus (RSV). (b) Expression of ACE2 in Calu‐3 cells treated with mock or Middle East respiratory syndrome coronavirus (MERS‐CoV) 6hpi and 24hpi. (n = 3). Significance is determined with one‐way analysis of variance (ANOVA) test, **p < .01. (c) Expression of Ace2 in lung endothelial cells 0 and 72 hr after lipopolysaccharide (LPS) injection in mice (n = 10 in 0 hr and n = 12 in 72 hr). Significance is determined with two‐tailed unpaired Student's t test, *p < .05. (d) Schematic review of ACE2 expression providing insights into severe acute respiratory syndrome coronavirus (SARS‐CoV‐2) blood entry and heart injury