SARS-CoV-2 Structural Proteins Exposure Alter Thrombotic and Inflammatory Responses in Human Endothelial Cells

Abstract

Introduction We have experienced a pandemic induced by the interaction of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) structural proteins with innate structures. These interactions are especially prevalent for patients with underlying pathologies, such as cardiovascular diseases. However, there has been limited work to uncover the range of responses induced by SARS-CoV-2 structural proteins. Thus, our objective was to investigate how endothelial cell pro-thrombotic and pro-inflammatory responses are altered after exposure to SARS-CoV-2 spike, nucleocapsid, and membrane-envelope proteins. We hypothesized that after a short duration exposure, endothelial cells would have a heightened thrombotic and inflammatory potential. With longer exposures, this may lead to altered disease progression and the observed increased mortality and morbidity rates in patients with underlying vascular pathologies. Methods To test this hypothesis, human endothelial cells were exposed to SARS-CoV-2 structural proteins. After the exposure, the expression of thrombomodulin, PECAM-1, connexin-43, and gC1qR were assessed. In parallel, standard cell culture readouts were assessed to determine if these incubations altered cell growth and metabolism. Results and Conclusions We observed significant increases in thrombotic and inflammatory marker expression, with no change to the cell culture parameters (with the exception of a reduction in cell density in response to one SARS-CoV-2 structural protein). Importantly, these observations were dependent on the viral structural protein the cells were exposed to, suggesting that the interactions of SARS-CoV-2 with innate cells is complex and must be uncovered. Combined, this suggests that SARS-CoV-2 structural proteins can regulate inflammatory and thrombotic responses that underlie common pathologies observed during COVID-19.

Complement-mediated microvascular injury and thrombosis in the pathogenesis of severe COVID-19: A review

“…They reported a specific proteomic signature of strongly regulated proteins in both critically and non-critically ill patients, compared to healthy subjects, including proteins involved in the acute phase response (C-reactive protein [CRP], serum amyloid A, and ferritin), immune-response (C1R, C4A/C4B, MBL2 and SERPING1), and coagulation (proteins of the intrinsic and extrinsic coagulation cascade, Kininogen-1), and reported that the C1r complement subcomponent is highly associated with disease severity, with an AUC of 0.93 (sensitivity: 89%; specificity: 82%). Consistent with the above findings, Freda et al [ 83 ] observed significant increases in thrombotic and inflammatory marker expression (thrombomodulin, PECAM-1) in human endothelial cells exposed to SARS-CoV-2 structural proteins. Kaiser et al [ 84 ] analyzed the proteome of neutrophils in severe COVID-19 and reported a unique proteomic signature of increased IL-8 secretion associated with increased D-dimer and neutrophil extracellular trap (NET) production, elevated complement factors (C1R, C1S, C5, C6, C7, C8 and C9), and fibrinogen binding, further uncovering a procoagulant role of inflammation and complement pathways.…”

Effects of Drugs Formerly Proposed for COVID-19 Treatment on Connexin43 Hemichannels

“…At different levels in the pathogenesis of COVID-19, Cx43 hemichannels can be involved in the initiation and dissemination of inflammatory processes. Recently, it was reported that Cx43 expression levels in human epithelial cells are upregulated upon exposure to SARS-CoV-2 [51]. SARS-CoV-2 starts causing damage to the cells at the pulmonary level, where the virus infects alveolar type II cells and alveolar macrophages, resulting in pneumonia and acute respiratory distress syndrome [12,52,53].…”

Novel Strategies for the Treatment of COVID-19

“…Platelet adhesion, activation, and aggregation play a pivotal role in thrombosis, which is a hallmark of severe COVID-19 [ 14 , 22 , 61 ]. An essential component in the platelet activation process is the interaction of adenosine diphosphate with the platelet P2Y12 receptor [ 13 , 62 , 63 ].…”