Increased protease-activated receptor 1 autoantibodies are associated with severe COVID-19

Anti-protease-activated receptor 1 (PAR1) antibodies (abs) correlated with disease severity and survival. a) anti-PAR1 ab levels in serum samples from healthy controls (HC) (29 samples, 29 individuals) and patients with coronavirus disease 2019 (COVID-19), either hospitalised/non-intensive care unit (ICU) (59 samples, 45 individuals) or ICU treatment (52 samples, 29 individuals); linear mixed model (LMM) p=0.092 and 3.36×10⁻⁵, respectively; b) anti-PAR1 ab levels in serum samples from ICU-treated COVID-19 patients in the cohort (29 patients), stratified by the outcome thrombotic events and survival (LMM p=0.0062 and 0.0319, respectively); c) correlation analysis for anti-PAR1 abs in COVID-19 patients against D-dimers. The linear regression line with confidence interval is displayed; statistical analysis is based on LMM (p=0.0010); d) receiver operating characteristic (ROC) analysis of anti-PAR1 abs, D-dimers and combined (upper panels) as well as anti-PAR1 abs, interleukin (IL)-6 and combined (lower panels) for the clinical outcomes “thrombotic events” (left panels) and “survival” (right panels). Areas under the ROC curve (AUC) are indicated in the panels.