COVID-19 induces a hyperactive phenotype in circulating platelets

Background

Coronavirus disease 2019 (COVID-19), caused by novel coronavirus SARS-CoV-2, has to date affected over 13.3 million globally. Although high rates of venous thromboembolism and evidence of COVID-19-induced endothelial dysfunction have been reported, the precise aetiology of the increased thrombotic risk associated with COVID-19 infection remains to be fully elucidated.

Objectives

Here, we assessed clinical platelet parameters and circulating platelet activity in patients with severe and non-severe COVID-19.

Methods

An assessment of clinical blood parameters in patients with severe COVID-19 disease (requiring intensive care), patients with non-severe disease (not requiring intensive care), general medical in-patients without COVID-19 and healthy donors was undertaken. Platelet function and activity were also assessed by secretion and specific marker analysis.

Results

We show that routine clinical blood parameters including increased MPV and decreased platelet:neutrophil ratio are associated with disease severity in COVID-19 upon hospitalisation and intensive care unit admission. Strikingly, agonist-induced ADP release was dramatically higher in COVID-19 patients compared with non-COVID-19 hospitalized patients and circulating levels of PF4, sP-selectin and TPO were also significantly elevated in COVID-19.

Conclusion

Distinct differences exist in routine full blood count and other clinical laboratory parameters between patients with severe and non-severe COVID-19. Moreover, we have determined that COVID-19 patients possess hyperactive circulating platelets. These data suggest that abnormal platelet reactivity may contribute to hypercoagulability in COVID-19. Further investigation of platelet function in COVID-19 may provide additional insights into the aetiology of thrombotic risk in this disease and may contribute to the optimisation of thrombosis prevention and treatment strategies.

Essentials

• Routine platelet-related clinical blood parameters (MPV, PNR) are associated with disease severity in COVID-19.

• Agonist-induced ADP release is dramatically higher in COVID-19 patients compared with non-COVID-19 hospitalized patients.

• Circulating levels of PF4, sP-selectin levels and TPO are significantly elevated in COVID-19.

• Identification of a hyperactive platelet phenotype may warrant re-evaluation of current thrombotic prevention strategies in COVID-19 treatment.