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Objectives: Systemic inflammatory autoimmune diseases (SIADs) such as systemic lupus erythematosus (SLE), primary Sjögren's syndrome (pSS) and idiopathic inflammatory myopathies (myositis) are complex conditions characterized by shared circulating autoantibodies and clinical manifestations, including skin rashes, among others. This study aimed at elucidating the genetics underlying these common features., Methods: We performed targeted DNA sequencing of coding and regulatory regions from ~1,900 immune-related genes in a large SIAD cohort of 2,292 well-characterized Scandinavian patients with SLE, pSS and myositis, as well as 1,252 controls. A gene-based functionally-weighted genetic score for aggregate testing of all genetic variants, including rare variants, was complemented by in-silico functional analyses and in-vitro reporter experiments., Results: Case-control association analysis detected known and potentially novel genetic loci in agreement with previous genetic and transcriptomics findings linked to the SIAD autoimmune background. Intriguingly, case-case comparisons between patient subgroups with and without specific autoantibodies revealed that the subgroups defined by ANA and anti-dsDNA antibodies have unique genetic profiles reflecting their heterogeneity. When focusing on clinical features, we overall showed that DUSP1 protective genetic variants lead to increased gene expression and potentially to anti-inflammatory effects on the SIAD-associated skin phenotype. This is consistent with recent genetic findings on eczema and with the previously reported downregulation of the MAPK signaling-related gene DUSP1 in other skin disorders., Conclusion: Together, this suggests common molecular mechanisms potentially underlying overlapping clinical manifestations shared among different disorders and informs clinical heterogeneity, which could be translated to improve disease diagnostic and treatment, also in more generalized disease frameworks., (This article is protected by copyright. All rights reserved.)

Objectives: Adverse pregnancy outcomes are more common in women with systemic lupus erythematosus (SLE) compared with healthy women, but we lack prognostic biomarkers. Plasma interferon alpha (IFNα) protein levels are elevated in a subgroup of pregnant women with SLE, but whether this is associated with pregnancy outcomes is unknown. We investigated the relationship between IFNα, adverse pregnancy outcomes and the presence of autoantibodies in SLE pregnancy., Methods: We followed 76 women with SLE prospectively. Protein levels of IFNα were quantified in plasma collected in the 2nd and 3rd trimester with single-molecule array. Positivity for antinuclear and antiphospholipid antibodies was assessed during late pregnancy with multiplexed bead assay. Clinical outcomes included the adverse pregnancy outcomes small for gestational age (SGA), preterm birth, and preeclampsia., Results: During SLE pregnancy, women with SGA infants compared with those without had higher levels of plasma IFNα protein, and IFNα positivity was associated with lower birth weight of the infant. Preterm birth was associated with autoantibodies against chromatin. IFNα protein levels associated positively with autoantibodies against chromatin, Smith/ribonucleoprotein (SmRNP) and RNP, but negatively with phospholipid antibodies., Conclusion: Elevated IFNα protein in plasma of women with SLE is a potential risk factor for lower birth weight of their infants. The association between IFNα and lower birth weight warrants further investigation regarding the pathophysiological role of IFNα during SLE pregnancy., (© The Author(s) 2024. Published by Oxford University Press on behalf of the British Society for Rheumatology.)

Objectives: Patients with SLE have an increased risk of comorbidities and impaired survival. We aimed to assess whether various thresholds of oral CS (OCS) can predict development of infections, comorbidities, malignancies and survival in SLE using data from national health registries in Sweden., Methods: All incident SLE cases, age >18 years, in Sweden (n = 5309) between 2005 and 2020 and matched population controls (n = 26 545) were included and followed until 2020, a total of 257 942 patient years. Data from national registers were retrieved including information from the National Prescribed Drug Register. Risk factors were analysed using time-dependent Cox regression models., Results: Compared with no OCS, >0 to <5.0 mg/day, 5.0-7.5 mg/day as well as >7.5 mg/day OCS predicted development of infections (pneumonia, influenza, herpes zoster and urinary tract infection), osteoporosis, osteonecrosis, gastroduodenal ulcers, cataracts, hypertension and mortality (all P < 0.05). OCS >0 to <5.0 mg/day was associated with lower hazard ratios for these comorbidities than higher doses of OCS. Fifteen years after diagnosis, 48% of patients were taking OCS at a median dose of 5.7 mg/day. A small reduction of OCS treatment 5 years after diagnosis in patients diagnosed with SLE 2006-10 compared with 2011-15 was observed, 49% vs 46% respectively (P = 0.039)., Conclusion: Results highlight the potential harm associated with even low OCS dose treatment in SLE and the need to judiciously use OCS at the lowest possible dose to maximize efficacy and minimize harm., (© The Author(s) 2023. Published by Oxford University Press on behalf of the British Society for Rheumatology.)