Massive platelet activation and thrombotic events characterize severe COVID-19, highlighting their critical role in SARS-CoV-2-induced immunopathology. Since there is a well-described expansion of myeloid-derived suppressor cells (MDSC) in severe COVID-19, we evaluated their possible role in platelet activation during SARS-CoV-2 infection. During COVID-19, a lower plasmatic L-arginine level was observed compared to healthy donors, which correlated with MDSC frequency. Additionally, activated GPIIb/IIIa complex (PAC-1) expression was higher on platelets from severe COVID-19 patients compared to healthy controls and inversely correlated with L-arginine plasmatic concentration. Notably, MDSC were able to induce PAC-1 expression in vitro by reducing L-arginine concentration, indicating a direct role of PMN-MDSC in platelet activation. Accordingly, we found a positive correlation between ex vivo platelet PAC-1 expression and PMN-MDSC frequency. Overall, our data demonstrate the involvement of PMN-MDSC in triggering platelet activation during COVID-19, highlighting a novel role of MDSC in driving COVID-19 pathogenesis.
【저자키워드】 COVID-19, MDSC, Platelet, L-Arginine, 【초록키워드】 platelet activation, severe COVID-19, SARS-COV-2 infection, immunopathology, in vitro, COVID-19 pathogenesis, expression, Critical, Frequency, Concentration, Ex vivo, healthy donors, healthy control, complex, positive correlation, driving, massive, triggering, Cell, thrombotic event, evaluated, activated, reducing, correlated, induce, highlighting, PAC-1, severe COVID-19 patient, 【제목키워드】 SARS-CoV-2, expansion, myeloid, suppressor,