POS0377 FIBROCYTES IN EARLY AND LONGSTANDING RHEUMATOID ARTHRITIS: A 6-MONTH TRIAL WITH REPEATED SYNOVIAL BIOPSY, IMAGING, AND LUNG FUNCTION TEST

Background: Fibrocytes are bone marrow-derived cells, that express both hematopoietic and stromal markers. In murine collagen-induced arthritis models circulating fibrocytes have been found to home inflamed joints enhance activity. The cell has, therefore, proposed be precursor cells for the fibroblast-like synoviocytes (FLS), which central in Rheumatoid Arthritis (RA) pathogenesis. levels further correlated with disease progression mortality interstitial lung (ILD) identified as a new treatment target. ILD is also an extra-articular manifestation of RA (RA-ILD), leading reduced diffusion capacity increased mortality. Objectives: To correlate level peripheral blood, synovial tissue, vitro culture changes activity, imaging, pulmonary function. Methods: Twenty patients early (ERA) 20 longstanding (LRA) were enrolled six months prospective study. Sixteen undergoing wrist arthroscopy healthy controls. underwent function tests, ultrasound, ultrasound-guided needle biopsy same wrist, at baseline months. Wrist magnetic resonance imaging was performed (all) (ERA). Circulating measured by flow cytometry, number monocytes differentiated fibrocytes, biopsies counting histological sections. Results: Fibrocyte did not decline during trial despite effective treatment. primarily located around vessels subintimal area synovium (Figure 1A 1B, marked arrows). ERA group, synovitis assessed ultrasound moderate strongly respectively increase fibrocyte levels. Increased MRI moderately numbers cultured fibrocytes. Absolute overall weakly negatively forced ventilatory 1C 1D). Conclusion: Our findings point key mediators pathogenesis, possible pathogenic link between process affection. Studies needed investigate if therapies targeting differentiation/migration could path forward RA/RA-ILD Disclosure Interests: None declared