Platelets contribute to disease severity in COVID-19.

Area of Science:

• Hematology
• Virology
• Immunology

Background:

• COVID-19 is associated with inflammation, immune dysregulation, and thrombosis.
• Platelets play a crucial role in thrombosis, inflammation, and immunity.
• Understanding platelet involvement in COVID-19 pathogenesis is critical.

Purpose of the Study:

• To investigate the impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on platelet phenotype.
• To characterize platelet activation, aggregation, and transcriptomic changes in COVID-19 patients.

Main Methods:

• Analysis of platelet indices in 3915 hospitalized COVID-19 patients.
• Detection of SARS-CoV-2 in megakaryocytes and platelets from patient tissues and blood.
• Phenotypic and transcriptomic characterization of platelets from COVID-19 patients.
• In vitro mechanistic studies on SARS-CoV-2 interaction with megakaryocytes.

Main Results:

• Platelet count, size, and immaturity correlate with increased critical illness and mortality.
• SARS-CoV-2 virions were found within megakaryocytes and platelets.
• COVID-19 platelets exhibited hyperreactivity (increased aggregation, P-selectin, CD40 expression).
• Distinct prothrombotic platelet transcriptomic profiles were observed.

Conclusions:

• Platelet characteristics are linked to COVID-19 severity and mortality.
• SARS-CoV-2 directly affects megakaryocytes and platelets, altering their function and transcriptome.
• These platelet alterations contribute to COVID-19 pathogenesis.