Generation of Inhibitory Autoantibodies to ADAMTS13 in Coronavirus Disease 2019

ObjectivesIt has recently been shown that von Willebrand factor (vWf) multimers may be a key driver of immunothrombosis in Coronavirus disease 2019 (COVID-19). Since COVID-19 is associated with an increased risk of autoreactivity, the present study investigates, whether the generation of autoantibodies to ADAMTS13 contributes to this finding. DesignObservational prospective controlled multicenter study. SettingBlood samples and clinical data of patients with COVID-19 were collected regularly during hospitalization in the period from April to November 2020. Patients90 patients with confirmed COVID-19 of mild to critical severity and 30 healthy controls participated in this study. Measuerements and Main ResultsAntibodies to ADAMTS13 occurred in 31 (34.4%) patients with COVID-19. Generation of ADAMTS13 antibodies was associated with a significantly lower ADAMTS13 activity (56.5%, interquartile range (IQR) 21.25 vs. 71.5%, IQR 24.25, p=0.0041), increased disease severity (severe or critical disease in 90% vs. 62.3%, p=0.0189), and a trend to a higher mortality (35.5% vs. 18.6%, p=0.0773). Median time to antibody development was 11 days after first positive SARS-CoV-2-PCR specimen. ConclusionThe present study demonstrates for the first time, that generation of antibodies to ADAMTS13 is a frequent finding in COVID-19. Generation of these antibodies is associated with a lower ADAMTS13 activity and an increased risk of an adverse course of the disease suggesting an inhibitory effect on the protease. These findings provide a rationale to include ADAMTS13 antibodies in the diagnostic workup of SARS-CoV-2 infections.

COVID-19 is associated with relative ADAMTS13 deficiency and VWF multimer formation resembling TTP

BackgroundThrombotic microangiopathy (TMA) has been repeatedly described in COVID-19 and may contribute to SARS-CoV-2 associated hypercoagulability. The underlying mechanisms remain elusive. We hypothesized that endothelial damage may lead to substantially increased concentrations of Von Willebrand Factor (VWF) with subsequent relative deficiency of ADAMTS13. MethodsA prospective controlled trial was performed on 75 patients with COVID-19 of mild to critical severity and 10 healthy controls. VWF antigen (VWF:Ag), ADAMTS13 and VWF multimer formation were analyzed in a German hemostaseologic laboratory. ResultsVWF:Ag was 4.8 times higher in COVID-19 patients compared to healthy controls (p< 0.0001), whereas ADAMTS13 activities were not significantly different (p = 0.24). The ADAMTS13/VWF:Ag ratio was significantly lower in COVID-19 than in the control group (24.4{+/-}20.5 vs. 79.7{+/-}33.2, p< 0.0001). Fourteen patients (18.7%) undercut a critical ratio of 10 as described in thrombotic thrombocytopenic purpura (TTP). Gel analysis of multimers resembled the TTP constellation with loss of the largest multimers in 75% and a smeary triplet pattern in 39% of the patients. The ADAMTS13/VWF:Ag ratio decreased continuously from mild to critical disease (ANOVA p = 0.026). Moreover, it differed significantly between surviving patients and those who died from COVID-19 (p = 0.001) yielding an AUC of 0.232 in ROC curve analysis. ConclusionCOVID-19 is associated with a substantial increase in VWF levels, which can exceed the ADAMTS13 processing capacity resulting in the formation of large VWF multimers identical to TTP. The ADAMTS13/VWF:Ag ratio is an independent predictor of severity of disease and mortality. These findings render further support to perform studies on the use of plasma exchange in COVID-19 and to include VWF and ADAMTS13 in the diagnostic workup.

Estimation of platelet function under high shear conditions to assist a rapid diagnosis of Heyde Syndrome.

Loss of high molecular weight von Willebrand factor (VWF) multimers in patients suffering from aortic valve stenosis and gastrointestinal (GI) bleeding has been regarded as the missing link between aortic stenosis and bleeding. Electrophoretic analysis of VWF multimers is laborious and time-consuming. Further, determination of overall haemostatic competence rather than evaluation of restricted portions thereof may be advantageous. Accumulating evidence suggests that, recently developed in vitro and ex vivo platelet reactivity tests under high shear conditions mirror the in vivo situation. We report on a case of a 79-year-old man who presented with recurrent GI bleeding and severe aortic stenosis. Platelet function testing under high shear conditions using the commercially available cone and plate(let) analyser-Impact-R revealed significantly impaired shear dependent platelet function, suggesting VWD. This test offers an easy to use diagnostic tool to evaluate platelet function in suspected Heyde Syndrome thus leading to immediate tailored patient's management.