Influenza A Virus Modulates ACE2 Expression and SARS-CoV-2 Infectivity in Human Cardiomyocytes

Rationale: Influenza A virus (IAV) and SARS-CoV-2 are both acute respiratory viruses currently circulating in the human population. Prior IAV infection enhances SARS-CoV-2 infectivity and lung pathogenesis in mice; however, underlying mechanisms and the extent that co-infection leads to involvement of other organs in disease severity remains unknown. Objective: Herein, we investigated the impact of prior IAV infection on SARS-CoV-2 pathogenesis and cardiomyocyte function. Methods and Results: IAV infection in human primary lung epithelial cells, lung fibroblasts, macrophages, cardiac fibroblasts, and hiPSC-Cardiomyocytes enhances the expression of, the SARS-CoV-2 receptor ACE2. Also, we found that IAV infection enhances levels of ACE2 in the lungs of mice and humans. Interestingly, we detected poorly glycosylated ACE2 in A549 lung cells, primary lung epithelial cells, and cardiac fibroblasts. In contrast, expression of a heavily glycosylated form of ACE2 is induced by IAV infection in cardiomyocytes. In all cell types, IAV infection enhances SARS-CoV-2 spike protein binding and viral entry. However, efficient SARS-CoV-2 replication was uniquely inhibited in cardiomyocytes. Glycosylation of ACE2 correlated with enzymatic conversion of its substrate Ang II, induction of eNOS and nitric oxide production, providing a mechanistic underpinning for restricted viral replication in cardiomyocytes. Conclusions: Our results indicate that IAV-mediated induction of ACE2 is double-edged, providing increased risk for SARS-CoV-2 coinfection in human  lung epithelial cells and cardiac fibroblasts , while limiting SARS-CoV-2 replication in cardiomyocytes. We conclude that differential glycosylation of ACE2 may be a molecular determinant- not of SARS-CoV-2 infection, but of replication. Funding: The work was supported by NIH grants AI 146252 and AI 146690. Declaration of Interests: The authors declare that they have no conflict of interest. Ethics Approval Statement: All procedures were approved by the OSU IACUC.We have obtained ethics approval from the Ohio State University, The Institutional Animal Care and Use Committee (#2016A00000100-R1), Institutional Biosafety Committee (#2020R00000135) for animal work and Institutional Review Board (#2020H0222) for human subjects.