Antibody‐mediated procoagulant platelet formation in COVID‐19 is AKT dependent

Abstract

Background Thromboembolic events are frequently reported in patients infected with the SARS‐CoV‐2. Recently, we observed that platelets from patients with severe COVID‐19 infection express procoagulant phenotype. The molecular mechanisms that induce the generation of procoagulant platelets in COVID‐19 patients are not completely understood. Objectives In this study, we investigated the role of AKT (also known as Protein Kinase B), which is the major downstream effector of PI3K (phosphoinositid‐3‐kinase) (PI3K/AKT) signaling pathway in platelets from patients with COVID‐19. Patients and Methods Platelets, Sera and IgG from COVID‐19 patients who were admitted to the intensive care unit (ICU) were analyzed by flow cytometry as well as western blot and adhesion assays. Results Platelets from COVID‐19 patients showed significantly higher levels of phosphorylated AKT, which was correlated with CD62p expression and phosphatidylserine (PS) externalization. In addition, healthy platelets incubated with sera or IgGs from ICU COVID‐19 patients induced phosphorylation of PI3K and AKT and were dependent on Fc‐gamma‐RIIA (FcγRIIA). In contrast, ICU COVID‐19 sera mediated generation of procoagulant platelets was not dependent on GPIIb/IIIa. Interestingly, the inhibition of phosphorylation of both proteins AKT and PI3K prevented the generation of procoagulant platelets. Conclusions Our study shows that pAKT/AKT signaling pathway is associated with the formation of procoagulant platelets in severe COVID‐19 patients without integrin GPIIb/IIIa engagement. The inhibition of PI3K/AKT phosphorylation might represent a promising strategy to reduce the risk for thrombosis in patients with severe COVID‐19.

Longitudinal multiparametric characterization of platelet dysfunction in COVID-19: Effects of disease severity, anticoagulation therapy and inflammatory status

“…We presume that this can be caused by the fact that Hottz et al were considering percent of CD41/CD63 positive platelets [19] , while we were considering the platelet population in general. Pelzl et al have recently shown that incubation of healthy donor platelets with COVID-19 patients' serum cause procoagulant platelet formation in an Akt-dependent manner [57] . This observation seemingly contradicts our findings on incubation of healthy donor platelets with COVID-19 patient's plasma ( Fig.…”

Immune-Mediated Platelet Activation in COVID-19 and Vaccine-Induced Immune Thrombotic Thrombocytopenia

“…Sera from COVID-19 patients activate platelets in serotonin release assay and this effect was completely inhibited by blocking FcyRIIa with mAb IV.3 ( 8 ). Most importantly, it has been reported that sera and IgG fractions from these patients are able to induce a procoagulant phenotype in platelets from healthy donors ( 9 , 10 ) and are associated with phosphatidylserine externalization and P-selectin expression ( 11 ). On activated platelets, phosphatidylserine acts as a binding site for plasma coagulation factors and propagates actin and fibrin formation ( 43 – 45 ).…”

“…Taken together these results indicate that one factor in the serum activates the inside-out signaling cascade and promotes the translocation of negatively charged phospholipids to the outer membrane leaflet. Our group recently showed that IgGs from severe COVID‐19 patients induce platelet activation through the PI3K/AKT signaling pathway via FcγRIIA ( 10 ). In particular, inhibition of FcγRIIA blocked AKT and PI3K phosphorylation preventing antibody-mediated platelet adhesion and thrombus formation in severe COVID-19 patients ( 10 ).…”

“…Our group recently showed that IgGs from severe COVID‐19 patients induce platelet activation through the PI3K/AKT signaling pathway via FcγRIIA ( 10 ). In particular, inhibition of FcγRIIA blocked AKT and PI3K phosphorylation preventing antibody-mediated platelet adhesion and thrombus formation in severe COVID-19 patients ( 10 ). More importantly, the inhibition of AKT and PI3K phosphorylation, with BAY1125976 or BYL719, prevented the generation of procoagulant platelets ( 10 ), which could be a promising therapeutic target in COVID-19 patients.…”

“…However, it is not clear, how platelets are activated in COVID-19 patients. IgG from COVID-19 patients induces platelet activation in an Fcgamma-RIIA receptor (FcgRIIA) dependent manner (8)(9)(10)(11). SARS-CoV-2 can activate platelets and result in programmed cell death and extracellular vesicle release (12).…”