SARS-CoV-2 Spike Proteins and Cell–Cell Communication Inhibits TFPI and Induces Thrombogenic Factors in Human Lung Microvascular Endothelial Cells and Neutrophils: Implications for COVID-19 Coagulopathy Pathogenesis

Abstract

In SARS-CoV-2-infected humans, disease progression is often associated with acute respiratory distress syndrome involving severe lung injury, coagulopathy, and thrombosis of the alveolar capillaries. The pathogenesis of these pulmonary complications in COVID-19 patients has not been elucidated. Autopsy study of these patients showed SARS-CoV-2 virions in pulmonary vessels and sequestrated leukocytes infiltrates associated with endotheliopathy and microvascular thrombosis. Since SARS-CoV-2 enters and infects target cells by binding its spike (S) protein to cellular angiotensin-converting enzyme 2 (ACE2), and there is evidence that vascular endothelial cells and neutrophils express ACE2, we investigated the effect of S-proteins and cell–cell communication on primary human lung microvascular endothelial cells (HLMEC) and neutrophils expression of thrombogenic factors and the potential mechanisms. Using S-proteins of two different SARS-CoV-2 variants (Wuhan and Delta), we demonstrate that exposure of HLMEC or neutrophils to S-proteins, co-culture of HLMEC exposed to S-proteins with non-exposed neutrophils, or co-culture of neutrophils exposed to S-proteins with non-exposed HLMEC induced transcriptional upregulation of tissue factor (TF), significantly increased the expression and secretion of factor (F)-V, thrombin, and fibrinogen and inhibited tissue factor pathway inhibitor (TFPI), the primary regulator of the extrinsic pathway of blood coagulation, in both cell types. Recombinant (r)TFPI and a thiol blocker (5,5′-dithio-bis-(2-nitrobenzoic acid)) prevented S-protein-induced expression and secretion of Factor-V, thrombin, and fibrinogen. Thrombomodulin blocked S-protein-induced expression and secretion of fibrinogen but had no effect on S-protein-induced expression of Factor-V or thrombin. These results suggests that following SARS-CoV-2 contact with the pulmonary endothelium or neutrophils and endothelial–neutrophil interactions, viral S-proteins induce coagulopathy via the TF pathway and mechanisms involving functional thiol groups. These findings suggest that using rTFPI and/or thiol-based drugs could be a viable therapeutic strategy against SARS-CoV-2-induced coagulopathy and thrombosis.

Plasma tissue factor pathway inhibitor levels in coronavirus disease 2019 patients: a systematic review and meta-analysis

“…As their in-vitro examination showed that plasma from patients with severe or moderate COVID-19 decreased the TFPI transcription or mRNA in these cells [24]. In agreement, Bhargavan and Kanmogne [45] found that exposure of primary human lung microvascular endothelial cells (HLMEC) or neutrophils to SARS-CoV-2 spike proteins induced transcription and expression of procoagulants (TF, F-V, F-II, and F-I) and inhibited transcription of TFPI in both cell types. In this regard, the study of FitzGerald et al [46] showed that despite the lack of increase in TFPI expression in SARSCoV-2-infected normal human bronchial epithelial cells (NHBEs), there was an increased TFPI expression in BAL fluid (BALF) from patients with COVID-19.…”

Extracellular Vesicle-Based SARS-CoV-2 Vaccine

“…However, there are some exceptions, such as cases with elevated D-dimer levels that are not seen in DIC, and with elevated D-dimer levels, even in mild cases without a cytokine storm. Combining these clinical findings and the fact that ACE2 is a novel SARS-CoV-2 infection receptor expressed in vascular endothelial cells, there are cases in which a virus that has directly entered the blood infects vascular endothelial cells and causes vascular injury, thereby inducing thrombus formation [ 67 , 68 ]. Furthermore, findings of SARS-CoV-2 infection in vascular endothelial cells and associated vasculitis have been reported.…”

The Novelty of mRNA Vaccines and Potential Harms: A Scoping Review

“…There is reason to believe that vaccines encoding the spike (S) protein of SARS-CoV-2 have additional mechanisms of harm, owing to the biological impacts of S protein specifically. There is a wide literature [150][151][152][153], and it is beyond the scope of this review to cover this in significant depth. However, the addition of spike protein adds another factor in assessing the complexity of RNA vaccines.…”