Associations between the von Willebrand Factor-ADAMTS13 Axis, Complement Activation, and COVID-19 Severity and Mortality.

ABSTRACT

BACKGROUND: Endothelial and complement activation were both associated with immunothrombosis, a key determinant of COVID-19 severity, but their interrelation has not yet been investigated. OBJECTIVES: We aimed to determine von Willebrand factor (VWF) antigen (VWFAg) concentration, VWF collagen binding activity (VWFCBA), a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13) activity (ADAMTS13Ac), and their ratios in hospitalized COVID-19 patients, and to investigate how these parameters and their constellation with complement activation relate to disease severity and in-hospital mortality in COVID-19. METHODS: Samples of 102 hospitalized patients with polymerase chain reaction-confirmed severe acute respiratory syndrome coronavirus 2 positivity were included in our observational cohort study. Patients were stratified according to the peak severity of COVID-19 disease in agreement with the World Health Organization ordinal scale. Twenty-six convalescent plasma donors with previous COVID-19 disease formed the control group. VWFAg concentration and VWFCBA were determined by enzyme-linked immunosorbent assay (ELISA); ADAMTS13Ac was determined by fluorescence resonance energy transfer. Complement C3 and C3a were measured by turbidimetry and ELISA, respectively. Clinical covariates and markers of inflammation were extracted from hospital records. RESULTS: VWFAg and VWFCBA were elevated in all groups of hospitalized COVID-19 patients and increased in parallel with disease severity. ADAMTS13Ac was decreased in patients with severe COVID-19, with the lowest values in nonsurvivors. High (> 300%) VWFAg concentrations or decreased (< 67%) ADAMTS13Ac were associated with higher risk of severe COVID-19 disease or in-hospital mortality. The concomitant presence of decreased ADAMTS13Ac and increased C3a/C3 ratio-indicating complement overactivation and consumption-was a strong independent predictor of in-hospital mortality. CONCLUSION: Our results suggest that an interaction between the VWF-ADAMTS13 axis and complement overactivation and consumption plays an important role in the pathogenesis of COVID-19.