Patients with coronavirus disease 2019 (COVID-19) have elevated D-dimer levels. Early reports describe high venous thromboembolism (VTE) and disseminated intravascular coagulation (DIC) rates, but data are limited. This multicenter, retrospective study described the rate and severity of hemostatic and thrombotic complications of 400 hospital-admitted COVID-19 patients (144 critically ill) primarily receiving standard-dose prophylactic anticoagulation. Coagulation and inflammatory parameters were compared between patients with and without coagulation-associated complications. Multivariable logistic models examined the utility of these markers in predicting coagulation-associated complications, critical illness, and death. The radiographically-confirmed VTE rate was 4.8% (95% CI, 2.9-7.3%) and the overall thrombotic complication rate was 9.5% (6.8-12.8%). The overall and major bleeding rates were 4.8% (2.9-7.3%) and 2.3% (1.0-4.2%). In the critically ill, radiographically-confirmed VTE and major bleeding rates were 7.6% (3.9-13.3%) and 5.6% (2.4-10.7%). Elevated D-dimer at initial presentation was predictive of coagulation-associated complications during hospitalization [D-dimer >2,500 ng/mL, adjusted OR for thrombosis, 6.79 (2.39-19.30), adjusted OR for bleeding, 3.56 (1.01-12.66)], critical illness, and death. Additional markers at initial presentation predictive of thrombosis during hospitalization included platelet count >450×109/L [adjusted OR, 3.56 (1.27-9.97)], C-reactive protein (CRP) >100 mg/L [adjusted OR, 2.71 (1.26-5.86)], and erythrocyte sedimentation rate >40 mm/h [adjusted OR, 2.64 (1.07-6.51)]. ESR, CRP, fibrinogen, ferritin, and procalcitonin were higher in patients with thrombotic complications than those without. DIC, clinically-relevant thrombocytopenia, and reduced fibrinogen were rare and were associated with significant bleeding manifestations. Given the observed bleeding rates, randomized trials are needed to determine any potential benefit of intensified anticoagulant prophylaxis in COVID-19 patients.

No abstract

Protein disulfide isomerase (PDI) is an oxidoreductase essential for folding proteins in the endoplasmic reticulum. The domain structure of PDI is a–b–b′–x–a′, wherein the thioredoxin-like a and a′ domains mediate disulfide bond shuffling and b and b′ domains are substrate binding. The b′ and a′ domains are connected via the x-linker, a 19-amino-acid flexible peptide. Here we identify a class of compounds, termed bepristats, that target the substrate-binding pocket of b′. Bepristats reversibly block substrate binding and inhibit platelet aggregation and thrombus formation in vivo. Ligation of the substrate-binding pocket by bepristats paradoxically enhances catalytic activity of a and a′ by displacing the x-linker, which acts as an allosteric switch to augment reductase activity in the catalytic domains. This substrate-driven allosteric switch is also activated by peptides and proteins and is present in other thiol isomerases. Our results demonstrate a mechanism whereby binding of a substrate to thiol isomerases enhances catalytic activity of remote domains.