Yves Allenbach

Objective: Anti-Ku antibodies (Abs) are rare and detected in various autoimmune diseases (AIDs), presenting in various phenotypes, potentially affecting different organs including the lungs. This study aimed to describe the characteristics and evolution of interstitial lung disease (ILD) in anti-Ku-positive patients. Methods: An observational, multicentre, retrospective study was conducted across 10 French University Hospitals between January 2010 and June 2025, including patients with anti-Ku Abs with ILD. Clinical data and all pulmonary function tests and chest CT scans available were reviewed for this study. ILD progression was defined using criteria inspired by the American Thoracic Society/European Respiratory Society/Japenese Respiratory Society/Asociación Latinoamericana de Tórax Clinical Practice Guidelines, applied across the entire follow-up period rather than within the 12-month timeframe, to capture all clinically meaningful progression events. To account for event timing, time to ILD progression was analysed as a time-to-event outcome using Cox proportional hazards models. Results: Among 154 anti-Ku-positive patients (51 with idiopathic inflammatory myopathy, 46 with systemic lupus erythematosus, 30 with Sjögren’s disease, 27 with systemic sclerosis), 60 (39%) had ILD (68% women, median age 56 years). The predominant ILD pattern was fibrotic non-specific interstitial pneumonia (27%, n=16). ILD was already present at AID diagnosis in 48 patients (80%). Forty-five (75%) patients progressed after a median time of 4 (2–11) years. Male sex (adjusted HR (aHR) 2.7; 95% CI 1.4 to 5.2) was associated with ILD progression. When the 12-month cut-off was strictly applied, only six patients fulfilled the progressive fibrosing ILD definition. Baseline pulmonary fibrosis was present in 34 (57%) patients and was associated with a reduced survival when adjusting for age at ILD diagnosis and cardiac involvement (aHR 6.5, 95% CI 1.5 to 28.2). Conclusion: ILD occurred in 39% of anti-Ku-positive patients and progressed in 75% of them, underscoring the importance of systematic ILD screening and monitoring in these patients.

Objectives: Gastrointestinal (GI) involvement in myositis is a severe extra muscular manifestation with potentially life-threatening outcomes. However, it remains poorly characterized. We aimed to evaluate the prevalence of GI involvement in dermatomyositis (DM) and to describe its characteristics in anti-NXP2 DM. Methods: The prevalence of GI involvement across DM subgroups was assessed in a retrospective monocentric DM cohort (n = 119). It was further investigated in a retrospective multicentric cohort of anti-NXP2 DM (n = 48). GI involvement (defined as any symptomatic GI lesion, excluding isolated dysphagia) was considered severe when requiring surgery and/or intensive care unit admission. Results: In the monocentric DM cohort, severe GI involvement was observed in 18% of anti-NXP2 patients and 6% of anti-MDA5 patients. Severe GI involvement was significantly more frequent in anti-NXP2 patients compared with other DM subgroups (hazard ratio 8.85 [95% CI 1.62–48.35]). In the multicentric anti-NXP2 cohort, severe GI involvement (including four digestive perforations and three digestive haemorrhages) occurred in 12.5% of patients. Anti-NXP2 patients with severe GI involvement were significantly younger (median age 24.5 vs 42.5 years; p< 0.01) and more frequently presented with facial oedema at diagnosis (83% vs 33%; p= 0.03). At the time of GI involvement, 78% of anti-NXP2 patients had concomitant skin and/or muscle disease activity. No deaths were reported. Conclusion: Severe GI involvement represents a life-threatening complication in DM and is mainly associated with anti-NXP2 antibody. In anti-NXP2 DM, young age and facial oedema are associated with severe GI involvement.

Skeletal muscle regeneration is driven by muscle stem cells (MuSCs), which proliferate, differentiate and fuse to reform myofibers and restore muscle function. This myogenesis process is driven both by intrinsic MuSC properties and extrinsic cues. While coordinated inflammatory signals are necessary for healthy regeneration, chronic inflammation participates in various pathologies affecting the skeletal muscle. In the idiopathic inflammatory myopathy dermatomyositis (DM), MuSCs exhibit impaired myogenesis in vitro, indicating that they may have acquired intrinsic defects, contributing to the disease and providing a mechanism for sustained patient muscle weakness despite efficient anti-inflammatory treatments. Here, we investigated the transcriptomic regulation of DM-derived MuSCs, with a focus on the H3.3 histone variant which regulates myogenesis progression. DM-derived MuSCs were unable to effectively execute the myogenic transcriptional program during in vitro differentiation. They exhibited an activated canonical TNF-⍺ signaling. They also showed reduced expression of H3.3 and its chaperone genes, coupled with a decrease in H3.3 deposition across the entire genome, and particularly at myogenic regulatory factor loci. The loss of H3.3 combined with elevated TNF-⍺ signaling was associated with a failure of DM-derived MuSCs to achieve myogenesis, suggesting a mechanistic link between epigenetic dysregulation and defective muscle regeneration in humans.

Immune checkpoint inhibitor–induced myotoxicity (ICI-M) comprises myocarditis, myositis, and myasthenia gravis–like syndrome, demanding rapid recognition and therapy. Using immunophenotyping and transcriptomics analysis from blood and muscle, we identified distinct CD38 ^hi and KIR ⁺ CD8 T cells in ICI-M. Abatacept rescued patients and altered the composition and clonality of these cells. Dynamics of CD38 ^hi and KIR ⁺ CD8 T cells effectively supported therapeutic monitoring, offering personalized treatment in life-threatening irAEs.