EPAC regulates von Willebrand factor secretion from endothelial cells in a PI3K/eNOS-dependent manner during inflammation

Abstract

Coagulopathy is associated with both inflammation and infection, including infection with the novel SARS-CoV-2 (COVID-19). Endothelial cells (ECs) fine tune hemostasis via cAMP-mediated secretion of von Willebrand factor (vWF), which promote the process of clot formation. The exchange protein directly activated by cAMP (EPAC) is a ubiquitously expressed intracellular cAMP receptor that plays a key role in stabilizing ECs and suppressing inflammation. To assess whether EPAC could regulate vWF release during inflammation, we utilized our EPAC1-null mouse model and revealed an increased secretion of vWF in endotoxemic mice in the absence of the EPAC1 gene. Pharmacological inhibition of EPAC1 in vitro mimicked the EPAC1-/- phenotype. EPAC1 regulated TNFα-triggered vWF secretion from human umbilical vein endothelial cells (HUVECs) in a phosphoinositide 3-kinases (PI3K)/endothelial nitric oxide synthase (eNOS)-dependent manner. Furthermore, EPAC1 activation reduced inflammation-triggered vWF release, both in vivo and in vitro. Our data delineate a novel regulatory role of EPAC1 in vWF secretion and shed light on potential development of new strategies to controlling thrombosis during inflammation.

Effect of SARS-CoV-2 proteins on vascular permeability

“…Recent observations suggest that these pathologies are mainly due to increased coagulation and vascular dysfunction ( Lee et al, 2021 ; Libby and Lüscher, 2020 ; Siddiqi et al, 2020 ). It is currently believed that in addition to being a respiratory disease, COVID-19 might also be a ‘vascular disease’ ( Lee et al, 2021 ), as it may result in a leaky vascular barrier and increased expression of von Willebrand factor (VWF) ( Siddiqi et al, 2020 ), responsible for increased coagulation, cytokine release, and inflammation ( Siddiqi et al, 2020 ; Teuwen et al, 2020 ; Aid et al, 2020 ; Potus et al, 2020 ; Wazny et al, 2020 ; Pum et al, 2021 ; Barbosa et al, 2021 ; Lin et al, 2020 ; Matarese et al, 2020 ; Xiao et al, 2020 ). Recent studies suggest that the main mechanism disrupting the endothelial barrier occurs in several stages: First, a direct effect on the endothelial cells that causes an immune response of the vascular endothelium (endotheliitis) and endothelial dysfunction.…”

“…Recent studies suggest that the main mechanism disrupting the endothelial barrier occurs in several stages: First, a direct effect on the endothelial cells that causes an immune response of the vascular endothelium (endotheliitis) and endothelial dysfunction. Second, lysis and death of the endothelial cells Teuwen et al, 2020 ; Xiao et al, 2020 followed by sequestering of human angiotensin I-converting enzyme 2 (hACE2) by viral spike proteins that activate the kallikrein–bradykinin and renin–angiotensin pathways, increasing vascular permeability ( Teuwen et al, 2020 ; Varga et al, 2020 ). Last, overreaction of the immune system, during which a combination of neutrophils and immune cells producing reactive oxygen species, inflammatory cytokines (e.g., interleukin [IL]-1β, IL-6, and tumor necrosis factor), and vasoactive molecules (e.g., thrombin, histamine, thromboxane A2, and vascular endothelial growth factor), and the deposition of hyaluronic acid lead to disruption of endothelial junctions, increased vascular permeability, and leakage and coagulation ( Libby and Lüscher, 2020 ; Teuwen et al, 2020 ; Varga et al, 2020 ).…”

Age-Associated Increase in Thrombogenicity and Its Correlation with von Willebrand Factor

“…Inflammation, endothelial injury, and dysregulated immune response instigate assembly of membrane attack complex (MAC) on endothelial cells, which increases endothelial cytosolic Ca 2+ concentration that stimulates VWF release from Weible-Palade bodies [ 162 ]. Inflammatory cytokine TNF-alpha can regulate VWF expression indirectly by decreasing NO synthesis through inhibition of eNOS expression in endothelial cells [ 163 , 164 ]. Consistent with this, significantly decreased NO levels has been reported as a result of CoV-2 infection [ 165 , 166 ].…”

Molecular Analysis of SARS-CoV-2 Spike Protein-Induced Endothelial Cell Permeability and vWF Secretion

“…It is currently believed that, in addition to being a respiratory disease, COVID-19 might also be a ‘vascular disease’ [ 13 , 14 , 15 ], as it may result in a leaky vascular barrier and increased expression of von Willebrand factor (vWF), which is responsible for increased coagulation, cytokine release, and inflammation [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ]. In addition, thrombotic events occur in COVID-19 patients, which is known as COVID-19-associated coagulopathy (CAC) and endothelial-derived vWF may play a significant role in it.…”