Aberrant glycosylation of anti-SARS-CoV-2 spike IgG is a prothrombotic stimulus for platelets

Abstract

A subset of patients with COVID-19 become critically ill, suffering from severe respiratory problems and also increased rates of thrombosis. The causes of thrombosis in severely ill COVID-19 patients are still emerging, but the coincidence of critical illness with the timing of the onset of adaptive immunity could implicate an excessive immune response. We hypothesised that platelets might be susceptible to activation by anti-SARS-CoV-2 antibodies and contribute to thrombosis. We found that immune complexes containing recombinant SARS-CoV-2 spike protein and anti-spike IgG enhanced platelet-mediated thrombosis on von Willebrand Factor in vitro, but only when the glycosylation state of the Fc domain was modified to correspond with the aberrant glycosylation previously identified in patients with severe COVID-19. Furthermore, we found that activation was dependent on FcγRIIA and we provide in vitro evidence that this pathogenic platelet activation can be counteracted by therapeutic small molecules R406 (fostamatinib) and ibrutinib that inhibit tyrosine kinases Syk and Btk respectively or by the P2Y12 antagonist cangrelor.

Longitudinal multiparametric characterization of platelet dysfunction in COVID-19: Effects of disease severity, anticoagulation therapy and inflammatory status

“…5 F, G), these findings further confirm that immunothrombosis contributes to the platelet dysfunction in COVID-19 [10] , [28] . In line with the work of Bye et al, SARS-CoV-2 IgG can cause platelet hyperactivity [59] , what supports our findings that recombinant COVID-19 plasma reduces positive impact of LMWH therapy ( Fig. 3 A–E).…”

Antibody glycosylation in COVID-19

“…In the studies of Larsen et al, Hoepel et al, Bye et al and Pongracz et al, a common, liquid chromatography – mass spectrometry (LC–MS)-based method was employed to characterize total, anti-S, and to a limited extent anti-SARS-CoV-2 nucleocapsid (N) IgG glycosylation following their affinity purification [ 15 , 26 , 27 , 31 ]. This approach builds on microtitration plate-based adsorption of antibodies to viral proteins using a modification of enzyme-linked immunosorbent assay (ELISA) antibody detection methods.…”

“…Bye et al reported on the association of anti-S IgG1 afucosylation with prothrombotic platelet activation using in vitro models and highlighted the role of a platelet-specific Fc receptor FcγRIIa [ 27 ]. This finding is remarkable, as the FcγRIIa is not known to prefer afucosylated IgGs [ 2 ], and molecular insights as to how afucosylation contributes to prothrombotic platelet activation are lacking.…”

“…Together, these findings consistently revealed a marked, proinflammatory fucosylation signature on plasma-derived anti-S IgG1 originating from severely ill, SARS-CoV-2 infected inpatients [ 15 , 26 , 28 , 31 , 35 ]. Most studies additionally provide convincing multi-angle in vitro functional evidence associating anti-S IgG1 afucosylation with enhanced immune cell activation [ 15 , 26 , 28 , 35 ] or blood clotting abnormalities [ 27 ]. Interestingly however, the observed low-fucosylation signatures in hospitalized patients did not show the same associations with cytokines, chemokines and acute phase proteins as shown in in vitro assays [ 31 ].…”

COVID-19 Convalescent Plasma Is More than Neutralizing Antibodies: A Narrative Review of Potential Beneficial and Detrimental Co-Factors

“…Accordingly, elevated frequencies of CD16a+ monocytes were another antecedent in patients with more severe outcomes [43]. Immune complexes contained recombinant SARS-CoV-2 spike protein and aberrantly glycosylated anti-spike IgG with enhanced platelet-mediated thrombosis on von Willebrand Factor in vitro [69]; • Autoantibodies: SARS-CoV-2 infection can trigger autoimmune diseases such as myocarditis, and many single cases have been reported in the literature. In this review, we focus on large case series that help assess the prevalence of autoantibodies.…”