P156 Type I interferon is raised across connective tissue diseases and is associated with haematological abnormalities and specific autoantibody profiles

Abstract Background/Aims The overlapping clinical and serological features among connective tissue diseases (CTDs) suggest a shared molecular aetiology. A molecular taxonomy of CTDs offers new opportunities in clinical trial design, which can potentially be translated into targeted treatment. In a previous study of 164 patients, we identified a type I interferon (IFN) positive subgroup within an unselected CTD cohort associated with specific clinical and serological features. Here, we aim to investigate the relationship between type I IFN and the clinical and immunological phenotype in a larger CTD cohort and determine whether a distinct subpopulation of patients can be identified. Methods Adult patients with at least 1 CTD clinical feature and CTD-related autoantibody were recruited from five rheumatology centres in North West England into the Lupus Extended Autoimmune Phenotype (LEAP) cohort. A 24-gene interferon-stimulated gene (ISG) score was calculated using NanoString as described by Neasens et al. 2022. Results Most patients had lupus (36%). 160 of 344 (46.5%) patients had a positive ISG score across all CTDs with 64/125 (51%) of lupus patients (Fig.1). Patients with positive ISG score were younger and had longer disease duration (p 0.005 for both). There were no differences in mucocutaneous or internal organ involvement between the ISG subgroups. The ISG-positive group had significantly increased frequency of specific autoantibodies (anti-Smith, anti-Chromatin, anti-RNP, anti-Ro) and Rheumatoid Factor, and haematological abnormalities (lower haemoglobin, and lower total white cell and neutrophil counts) in an adjusted model including the CTD subtype. Conclusion In CTD patients, IFN type I positivity was identified across a subset of patients of all CTDs and is associated with specific autoantibodies and haematological parameters; these results support the findings of our previous smaller study. The identification of an IFN I-positive subgroup within an unselected CTD regardless of clinical diagnosis supports a molecular-based approach to treatment. Disclosure A. Madenidou: Grants/research support; Janssen and UCB. G.I. Rice: None. S. Dyball: Grants/research support; UCB, Novartis,Eli Lilly. B. Parker: Honoraria; Fresenius-Kabi and AbbVie. Member of speakers’ bureau; Eli Lilly and Roche. Grants/research support; Genzyme/Sanofi and GlaxoSmithKline. T.A. Briggs: Grants/research support; Janssen. I.N. Bruce: Consultancies; AstraZeneca, Eli Lilly, GlaxoSmithKline, Merck Serono and UCB. Member of speakers’ bureau; AstraZeneca, GlaxoSmithKline and UCB. Grants/research support; Genzyme/Sanofi, GlaxoSmithKline, Roche, Novartis, Janssen and UCB.