Increased VWF and Decreased ADAMTS-13 in COVID-19: Creating a Milieu for (Micro)Thrombosis

Abstract von Willebrand factor (VWF) is a large adhesive multimeric protein involved in hemostasis. The larger the size (or number of VWF multimers), greater functionality protein. A deficiency or defect can lead to disease (VWD) and cause bleeding. Conversely, an increase may create environment that promotes thrombosis. ADAMS-13 (a disintegrin metalloproteinase with thrombospondin type 1 motif, member 13), sometimes called VWF-cleaving protease, primarily responsible for controlling VWF. most severe (<10% normal levels) ADAMTS-13 arises thrombotic thrombocytopenic purpura, condition characterized by presence ultralarge clinically resulting enhanced risk However, result from other pathological processes. Of relevance recent finding COVID-19 (coronavirus 2019) associated both increased levels activity as well generally decreased occasionally normal) ADAMTS-13. Thus, there alteration VWF/ADAMTS-13 axis, often described ratio reduced ADAMTS-13/VWF ratio). also high prothrombotic risk. imbalance be providing milieu (micro)thrombosis, clinical picture resembling secondary microangiopathy some patients. This review therefore assesses literature on VWF, ADAMTS-13, COVID-19. Whenever reported COVID-19, has always been identified raised (compared reference ranges control populations). Reports have included level (i.e., antigen) cases one more “activity” (e.g., collagen binding; platelet glycoprotein Ib [GPIb] binding, using ristocetin cofactor modern versions including VWF:GPIbR [recombinant] VWF:GPIbM [mutant]). reported, “normal” reduced; however, it should recognized still identify relative reduction individual cases. Some reports discuss ADAMTS-13/VWF) ratio, but very few provide actual numerical data.