SARS-CoV-2 Infects Endothelial Cells In Vivo and In Vitro

Abstract

SARS-CoV-2 infection can cause fatal inflammatory lung pathology, including thrombosis and increased pulmonary vascular permeability leading to edema and hemorrhage. In addition to the lung, cytokine storm-induced inflammatory cascade also affects other organs. SARS-CoV-2 infection-related vascular inflammation is characterized by endotheliopathy in the lung and other organs. Whether SARS-CoV-2 causes endotheliopathy by directly infecting endothelial cells is not known and is the focus of the present study. We observed 1) the co-localization of SARS-CoV-2 with the endothelial cell marker CD31 in the lungs of SARS-CoV-2-infected mice expressing hACE2 in the lung by intranasal delivery of adenovirus 5-hACE2 (Ad5-hACE2 mice) and non-human primates at both the protein and RNA levels, and 2) SARS-CoV-2 proteins in endothelial cells by immunogold labeling and electron microscopic analysis. We also detected the co-localization of SARS-CoV-2 with CD31 in autopsied lung tissue obtained from patients who died from severe COVID-19. Comparative analysis of RNA sequencing data of the lungs of infected Ad5-hACE2 and Ad5-empty (control) mice revealed upregulated KRAS signaling pathway, a well-known pathway for cellular activation and dysfunction. Further, we showed that SARS-CoV-2 directly infects mature mouse aortic endothelial cells (AoECs) that were activated by performing an aortic sprouting assay prior to exposure to SARS-CoV-2. This was demonstrated by co-localization of SARS-CoV-2 and CD34 by immunostaining and detection of viral particles in electron microscopic studies. Moreover, the activated AoECs became positive for ACE-2 but not quiescent AoECs. Together, our results indicate that in addition to pneumocytes, SARS-CoV-2 also directly infects mature vascular endothelial cells in vivo and ex vivo, which may contribute to cardiovascular complications in SARS-CoV-2 infection, including multipleorgan failure.

Pathogenic Basis of Thromboinflammation and Endothelial Injury in COVID-19: Current Findings and Therapeutic Implications

“…In addition, SARS-CoV-2 was detected in pulmonary endothelial cells by electron microscopy in critically ill patients with COVID-19 [ 119 ]. Furthermore, SARS-CoV-2 successfully infected engineered human blood vessel organoids and activated mature mouse aortic endothelial cells [ 120 , 121 ]. These findings support SARS-CoV-2 tropism for vascular endothelial cells.…”

Extracellular Vesicles and Thrombosis: Update on the Clinical and Experimental Evidence

“…Importantly, the presence of fragmented SARS-CoV-2 viral genome or proteins in platelets and endothelial cells, but possibly also other cell types involved in thrombosis and hemostasis, suggests that these cells also are direct targets of the virus and that the resulting cellular activation, dysfunction and death contributes to thrombosis in COVID-19 [214][215][216][217]. As in other forms of cellular activation, the release of procoagulant EVs also may play a significant role in the micro-and macrovascular thrombotic complications associated with COVID-19.…”

Well-Known and Novel Players in Endothelial Dysfunction: Updates on a Notch(ed) Landscape

“…Other histologic examinations of post-mortem lungs failed to show evidence of endothelial cell infection [72], and a pre-print study showed that aortic, microvascular, and blood outgrowth endothelial cells are resistant to in vitro infection with SARS-CoV-2 [73]. Strong evidence of infection and virus production in the endothelium of mice and non-human primates infected with SARS-CoV-2 have been recently obtained [74].…”