Analysis of synovitis patterns in early RA supports the importance of joint-specific factors.

BACKGROUND: Rheumatoid arthritis (RA) is classically considered a systemic disorder, but the role of local factors in driving synovial inflammation is increasingly being recognized. These joint-specific factors may consequently modulate disease phenotype. OBJECTIVES: Our goal was to study the spatial distribution of swelling, tenderness and erosions in a large cohort of early RA (ERA) patients, to assess for patterns of simultaneously-involved joint clusters. We also aimed to investigate the link between arthritis localization and phenotypic features such as bone erosions and response to methotrexate therapy. METHODS: DMARD-naive patients from the ERA UCLouvain Brussels cohort were included. Forty-four joints were clinically assessed for swelling and tenderness before treatment, and 6 months later for methotrexate-treated patients. Clusters of joints were identified using Principal component analysis and Cramer's correlation coefficients. Frequency of bone erosions and joint-specific response to methotrexate were compared across different clusters. RESULTS: 452 ERA patients were included. Analysis of the spatial distribution of swelling and tenderness allowed for the identification of 3 joint clusters that showed significant simultaneous involvement: (i) MTP1-5 joints, (ii) hand joints (MCPs and PIPs), and (iii) larger joints. These clusters were associated with different susceptibility to bone erosions and distinct clinical features, but similar local response (joint swelling resolution) to methotrexate. CONCLUSION: This is the first study investigating the spatial distribution of arthritis in a large cohort of early RA using an unbiased approach. We identify clusters of simultaneously involved joints, supporting the importance of local factors in driving synovitis in RA.

Anti-TNF Induced Sarcoidosis-Like Disease in Rheumatoid Arthritis Patients: Review Cases from the RA UCLouvain Brussels Cohort.

INTRODUCTION: Drug-induced sarcoidosis-like disease is a rare side effect of anti-tumor necrosis factor (anti-TNF) agents in rheumatoid arthritis (RA) patients. The most commonly involved organs in such condition are the lungs, skin, and lymph nodes. The aim of this study is to report the number of cases and the clinical manifestations of sarcoidosis induced by anti-TNF in our RA UCLouvain Brussels cohort. METHODS: All case records of RA patients ever treated with a TNF inhibitor and presenting anti-TNF induced sarcoidosis in our rheumatology centers from 2000 to 2021 were retrospectively reviewed. RESULTS: Our RA UCLouvain Brussels cohort includes 2492 patients. Among them, 697 patients have been or are exposed to a TNF inhibitor. Only four patients with sarcoidosis induced by anti-TNF were identified and reviewed. Patient 1 was classified as incomplete Heerfordt syndrome. Patient 2 was a case of sarcoid-like granulomatosis manifesting as life-threatening hypercalcemia, acute kidney injury and atypical parenchymal pneumopathy. Patients 3 and 4 developed pulmonary sarcoidosis with hilar adenopathies. The TNF inhibitor was etanercept for the first three patients and infliximab for the last one. The time occurrence of sarcoidosis was highly variable after anti-TNF exposure. All patients recovered after glucocorticoid treatment and the discontinuation of the anti-TNF agent. CONCLUSIONS: This case highlights this rare paradoxical side effect and the variability of the clinical presentation. Further studies should analyze the immunopathology of such conditions.