ABSTRACT
Background: COVID-19 convalescent plasma (CCP) has been suggested to be beneficial to prevent disease progression in COVID-19. However, concerns have been expressed whether plasma components in CCP can shift the already imbalanced coagulation system to a more hypercoagulable state. Aim(s): To investigate the effect of CCP on platelet phenotype and activation. Method(s): We investigated platelets from CCP donors who had a history of mild COVID-19 infection. Donors who did not have COVID-19 were used as controls (non-CCP donors). We analyzed phosphatidylserine (PS) externalization, CD62p expression, and GPVI shedding in healthy platelets after incubation with sera from CCP and non-CCP donors using flow cytometry. The study protocol was approved by the ethics committee of the University Hospital of Tubingen. (Figure Presented) Results: Forty-seven CCP donors [22 Male, 25 Female;and mean age (+/-SD) 41.4 +/- 13.7 years] with a history of mild COVID-19 infection were included. Median duration after acute COVID-19 infection was 97 days (range, 34-401). Compared to sera from non-CCP donors, sera from CCP donors did not induce higher PS externalization (Fold increase [FI] of PS positive platelets: 1.16% +/- 0.66 vs. 1.51% +/- 0.74, respectively, p = 0.11) or increased the rate of CD62p/PS double positive procoagulant phenotype (FI in CD62p/PS positive platelets: 1.86 +/- 0.87 vs. 1.37 +/- 0.63, respectively, p = 0.10) in platelets from healthy persons. Of note, CD62p expression in healthy platelets after incubation with sera from CCP plasma donors was significantly lower compared to sera from non-CCP donors (FI in CD62p: 2.09 +/- 1.36 vs. 1.16 +/- 0.45, p< 0.01). Sera-mediated GPVI shedding was similar between non-CCP and CCP donors (1.07 +/- 0.16 vs. 1.27 +/- 0.91, p = 0.52). Conclusion(s): Our findings support data from clinical studies, which indicate that transfusion of CCP to treat or prevent severe COVID-19 is not associated with increased risk of exacerbation of the coagulopathy in COVID-19.
ABSTRACT
Background: Accumulating evidence indicates an association between Sars-CoV-2 associated coagulopathy and increased platelet activation. The molecular mechanisms was investof thrombus formation in patients affected by COVID-19. Aims: To investigate the role of phosphoinositid-3-kinase/AKT (PI3K/AKT) signaling pathway in platelet activation in patients with COVID-19. Methods: The Activation status of platelets and PI3/AKT signaling in COVID-19 patients or after incubation of washed healthy platelets with patients' sera was analysed by flow cytometry and Western blot. The functionality was tested by platelets adhesion ability on fibrinogen with PI3K and AKT inhibitors was analysed in vitro. Results: Platelets from COVID-19 patients admitted to the intensive care unit (ICU) showed significantly higher expression of P-selectin (CD62). Western blot analysis showed that platelets from COVID-19 patients display increased phosphorylation of the PI3K as well as of the downstream target protein kinase B/AKT at Ser473 residue. More importantly, sera from these patients induced phosphorylation of PI3K and AKT in healthy donor platelets leading to enhanced activation, which was dependent on Fc-gamma-RIIA (FcγRIIA). The inhibition of AKT as well as PI3K prevented the enhanced activation, adhesion to fibrinogen as well as procoagulant platelet formation. Conclusions: Our study shows that pAKT/AKT signaling pathway is significantly associated with platelet activation in severe COVID-19 patients, which is mediated by FcγRIIA. The strong correlations between platelet activation and pAKT/AKT suggest that inhibiting PI3K/AKT phosphorylation might represent a promising strategy to prevent onset of thrombosis in patients with severe COVID-19.
ABSTRACT
Background : Coronavirus diesease-2019 (COVID-19) is associated with increased thromboembolic complications. COVID-19 related coagulotpathy (CAC) involves derangements in both cellular and plasma elements of the coagulation system. We found that COVID19 infection is accompanied with the development of procoagulant platelet phenotype and an increased resistance to clot lysis. As more people recover from COVID-19 infection but still develop thrombotic complications, discussion has begun over the possibility of persistent CAC even after the acute infection period. Aims : To investigate the platelet activation after remission of COVID-19 infection. Methods : We included plasma donors who had a PCR confirmed mild COVID-19 infection within the last 6 months (exCOVID-19 Group) in the study. A control group consisted of donors who did not have COVID-19. We collected citrate blood from study participant and investigated CD62p expression, Annexin V and GPIV shedding with flow cytometry. All participants gave informed consent and institutional ethics committee approved the study protocol. We compared the data with Mann-Whitney test using GraphPad Prism. Results : Twenty-four convalescent plasma donors (11 Male, 13 Female) with a history of COVID-19 infection were included. Mean age (SD) was 39 ± 13 years. Median duration (interquartile range) after acute COVID-19 infection was 82 days (73-106). Baseline GPIV shedding rate was higher in exCOVID-19 group (1 ± 0 vs. 1.13 ± 0.06). However, platelet response to collagen-related peptide (CRP) did not differ between both groups. Baseline CD62p expression and CD62p expression after activation with thrombin receptor associated protein (TRAP) was similar between exCOVID-19 group and control group. The percentage of CD62p and Annexin V double positive platelets was similar between groups. Conclusions : Our findings suggest that procoagulant platelet phenotype is not present after mild COVID-19. Further studies should investigate the alterations in plasma components of coagulation and fibrinolytic system after COVID-19.