Circulating microclots are structurally associated with Neutrophil Extracellular Traps and their amounts are strongly elevated in long COVID patients

BACKGROUND: The persistence of vasculo-thrombotic complications has been put forward as a possible contributing factor in the long COVID (LC) syndrome. OBJECTIVES: Given the recently reported separate demonstration of the association of LC with elevated levels of fibrin amyloid microclots (FAM) and with those neutrophil extracellular traps (NETs), markers that are linked to thromboinflammation, this study considers the association of FAM with NETs. RESULTS: The results show that NETs markers are quantitatively and structurally associated with the size and number of FAM in patients with LC. These markers showed a strong diagnostic performance, both independently and when combined. CONCLUSIONS: Our study revealed that NETs may be a component of circulating FAM, We suggest that higher NETs formation promotes the stabilization of FAM in the circulation, leading to deleterious effects which contribute causally to the LC syndrome.