Hedvig Mildner

Objective To determine whether autoantibodies against interferons are present and play a role in disease modulation in idiopathic inflammatory myopathies (IIMs).Methods We screened for autoantibodies against a large number of interferons (IFNs) and other cytokines in a cross-sectional observational cohort of Swedish patients with anti-synthetase syndrome (n=51) and dermatomyositis (n=48), matched together with blood donors (n=100) from general population, using both planar and suspension-based multiplex assays. A single patient with autoimmune polyendocrine syndrome, type-1 (APS-1), known to harbour autoantibodies that neutralise type-I interferons, was included as a reference biological positive. The functional ability of autoantibodies to neutralise type-I interferons was tested in vitro, using an IFN-α/β responsive cell reporter assay.Result The initial screening of plasma samples indicated a repertoire of autoantibodies in IIM patients against a number of common myositis-specific and myositis-associated antigens. On screening for autoantibodies against type-I, II or III interferons, we did not find any evidence of anti-IFN autoantibodies being present in any of the IIM patient subgroups or the blood donors from general population. Additionally, none of the tested plasma samples, except the APS-1, exhibited neutralisation of physiological concentration IFN-α2, further confirming a complete lack of functional autoantibodies against IFN-α subtypes in this cohort.Conclusions We did not detect neutralising autoantibodies against IFN-α and autoantibodies against other types of IFNs in a Swedish cohort of IIM patients. These findings contrast with the presence of autoantibodies against type-I IFNs in other systemic autoimmune diseases, such as systemic lupus erythematosus, characterised by type-I IFN overactivation.

While Coronavirus disease 2019 (COVID-19) vaccines have proven to be both effective and generally safe, rare but severe adverse events following immunization (AEFIs) are described. Autoantibodies to platelet factor-4 are associated with catastrophic thrombotic AEFIs, but comprehensive investigations of other autoantibodies are lacking. We aimed to detect and describe autoantibodies targeting coagulation-related proteins in a population-wide cohort (SWEDEGENE) including AEFIs attributed to COVID-19 vaccines in Sweden. Subjects were recruited from December 2020 to October 2022 and were stratified based on diagnosis and COVID-19 exposure. Screening was carried out in two phases, with a multiplex bead-based assay in the first subset (until September 2021) and with targeted assays for the second (until October 2022). Positivity was defined based on absolute, relative, and biological/technical thresholds. Patients with coagulation-related AEFIs were older and the Vaxzevria vaccine was overrepresented in this group. Two cases had antiphospholipid antibodies but none had PF4 antibodies. We identified six positives for protein S autoantibodies. Protein S concentrations were negatively correlated with autoantibody response in patients with immunoreactivity and functional analysis revealed low protein S activity in three subjects. Our population-wide analysis reveals cases with autoantibodies against protein S which possibly underlie coagulopathic AEFIs.

Type I interferons act as gatekeepers against viral infection, and autoantibodies that neutralize these signaling molecules have been associated with COVID-19 severity and adverse reactions to the live-attenuated yellow fever vaccine. On this background, we sought to examine whether autoantibodies against type I interferons were associated with adverse events following COVID-19 vaccination. Our nationwide analysis suggests that type I interferon autoantibodies were not associated with adverse events after mRNA or viral-vector COVID-19 vaccines.