ABSTRACT
Background: A major complication of COVID19 is severe endothelial injury with micro-and macro-thrombotic disease in the lung and other organs. Several studies have identified high levels of inflammatory cytokines ( cytokine storm ), powerful activators of the endothelium, in plasma of severe COVID19 patients;indeed, COVID19 plasma was shown to activate endothelial cells (EC) in vitro. A consequence of EC activation is loss of anti-coagulant function, with release of pro-thrombotic Von Willebrand Factor (VWF). High levels of plasma VWF in severe COVID19 patients indicate systemic endothelial activation and increased risk of thrombosis. Aim(s): To identify drugs that decrease endothelial activation and VWF release, which may have a therapeutic impact in COVID19 patients. Method(s): We established an in vitro model of endothelial activation driven by 6 cytokines selected because of their high levels in COVID19 plasma. Cells were treated with the 6-cytokine cocktail for 24 hr;endothelial activation was confirmed by a panel of markers including ICAM1, measured by RT-qPCR and immunofluorescence (IF). Result(s): The treatment induced release of VWF and increased VWF-platelet string formation in a platelet flow-based assay. To identify drugs that blocked cytokine-induced VWF release, a high-throughput screening was carried out in human umbilical vein EC (HUVEC);VWF and ICAM1 expression were detected by IF;DAPI was used as nuclear stain. High content imaging screen of 3049 drugs from FDA/EMA-approved drug libraries identified drugs able to decrease VWF release following cytokine treatment. Top hits from several therapeutic classes including anti-inflammatory, anti-viral and hormones were taken forward for validation. Two hits were confirmed to inhibit cytokine-induced VWF release and VWF-platelet string formation. Selected findings were validated in lung microvascular EC. Conclusion(s): This study identified candidate drugs that reduce the enhanced VWF release caused by the cytokine storm typical of severe COVID19;these may be beneficial in the treatment of the pro-thrombotic risk in COVID19 patients.