Abstract Th0026: Recombinant SARS-COV-2 Component Proteins Induce a Senescent Pulmonary Endothelial Cell Phenotype

Introduction: Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus (SARS-CoV-2), has both acute and chronic manifestations. Severe acute disease is associated with multiorgan failure and small vessel vasculopathy characterized by widespread microthrombi. Survivors, who have otherwise recovered from the acute disease, have an increased risk for cardiovascular complications including stroke and myocardial infarction (MI). Notably, this extended period of endothelial dysfunction is not only poorly understood, but specific diagnostic and therapeutic approaches are absent. We hypothesize that SARS-CoV-2-induced endothelial cell senescence contributes to pulmonary vascular microthrombi in acute disease and possibly increases the risk for later cardiovascular complications. Methods: Primary human pulmonary arterial endothelial cells (PAECs) were exposed to recombinant SARS-CoV-2 spike (S1) or nucleocapsid (N) protein, viral components that may circulate for weeks after acute COVID-19. The senescent cellular phenotype associated with S1 exposure was compared to three well-characterized inducers of senescence (etoposide, H 2 O 2 , and ionizing radiation). Senescence was assessed using a flow cytometric assay of SA-b-galactosidase activity, quantitative PCR determination of p21, Ki67, LAMB3, H2AX, and PURPL expression, and apoptosis resistance to serum withdraw as measured by caspase 3/7 activity. Results: SARS-CoV-2 S1 exposure, as well as all three known inducers of senescence, increased SA-b-galactosidase activity in PAECs. mRNA expression of p21, Ki67, LAMB3, H2AX, and PURPL was variable across the different inducers of senescence, with the effects of S1 protein being most similar to H 2 O 2 . Both S1 and N-protein exposure for 24h dose dependently resulted in significant apoptosis resistance. Conclusions: Our data support that SARS-CoV-2 protein-induced cellular senescence may contribute to COVID-19 vasculopathy and endothelial dysfunction during acute and convalescent illness. These findings suggest that therapeutically targeting endothelial senescence might mitigate early and late cardiovascular complications of COVID-19.