Alterations in pathways of complement and platelet signalling are evident following proteome profiling of plasma from patients with Vaccine Induced Immune Thrombotic Thrombocytopenia (VITT).

Abstract

Background: VITT is a rare life-threatening complication associated with adenovirus vector-based COVID-19 vaccines, characterised by thrombosis, thrombocytopenia, elevated D-dimer and anti-platelet factor 4 antibodies. The signalling pathways involved in this profoundly immunothrombotic disease continues to be described. Objective(s): To investigate the proteomic changes in plasma from patients with VITT compared to vaccinated patients with VTE alone and healthy control groups using two different platforms. Method(s): Plasma from 10 VITT patients and 14 asymptomatic volunteers post-vaccination were analysed using targeted Proximity Extension Assay (PEA) technology (Inflammation and Cardiovascular III Target panels; Olink Proteomics) and unbiased (non-targeted) Mass Spectrometry (MS) proteo-mics. The MS analysis included an additional 7 VITT samples and 14 controls. 10 patients with thrombosis post-vaccination but without VITT (VTE-no VITT) were also subjected to PEA analysis. Differential protein abundance between the groups was also performed to identify any similarities between the two methods. Result(s): PEA and MS plasma proteomics provided complementary results. When evaluating each method independently, 47 proteins with a primary difference in the VITT group were identified using PEA (44 upregulated, 3 downregulated). MS identified 53 significant protein differences between VITT vs control. Trend-analyses of differentially abundant proteinsin MS highlighted significant reactomes in the complement cascade, platelet activation, signalling and platelet aggregation in VITT samples. Conclusion(s): VITT is characterised by both unique and shared proteomic changes compared to VTE-no VITT and control samples. Our preliminary analyses indicate that VITT is associated with changes in complement and platelet activation.