PROLIFERATIVE SYNOVITIS, AN ULTRASOUND PATTERN ASSOCIATED WITH ACPA POSITIVE RHEUMATOID ARTHRITIS

Background:Seronegative (sero-) and seropositive (sero+) Rheumatoid Arthritis (RA) have different genetic, immunopathological and vascular morphology features, but no previous studies have analyzed if US characteristics differ between sero+ or sero- RA. Our preliminary studies suggest that sero+ RA is associated with an expansive synovitis pattern that we have called “proliferative synovitis” (PS)Objectives:To analyze potential differences between patients with RA according to their autoantibody status by using ultrasonography (US). We aimed to assess whether PS is associated with ACPA+ ptsMethods:We collected clinical, epidemiological data and bilateral carpal and hand US images of pts with RA. Synovial hypertrophy (SH), Power Doppler signal (PD) and total score (sum of scores of SH and PD) in wrist and hand (1-5 metacarpophalangeal) were assessed. We evaluated the presence of PS, defined as expansive synovial growth encompassing the concepts of synovial SH grade II and III. We performed synovial biopsies of a subgroup of pts using arthroscopy or US guided in order to see immunohistochemistry differences between “proliferative” and “flat” (non-proliferative) synovitis. Serum levels of angiogenic and inflammatory biomarkers were performedResults:Two hundred and five RA patients were collected. Overall, 173 (84.8%) pts were sero+ for RF (68.7%) or ACPA (74.6%), general characteristics are summarized in Table. No significant differences between sero+ and sero- pts in terms of disease activity or therapy were found. PS was present in 55.5% of sero+ pts (55.3% in RF+ and 58.2% in ACPA+ pts) and 16.1% of sero- pts (p=0.0001). Globally, 101 pts (49.2%) had PS. Ninety-six (95.0%) were RF or ACPA positive. Only 5 pts with sero- RA had PS (p=0.001). In the univariate analysis, significantly more pts with PS had erosive disease (72.3% vs 35.0% p=0.0001), higher US scores (p=0.0001) and more of them were taking conventional synthetic Disease-modifying anti-rheumatic drugs (csDMARD) (81.8% vs 69.6% p=0.05). No differences regarding disease activity were found.In the multivariate analysis erosions [OR 4.90 CI 95% (2.17-11.07) p=0.0001] and ACPA [OR 3.5 CI 95% (1.39-10.7) p=0.09] but not RF status [OR 0.74 CI 95% (0.31-1.71) p=0.483] were independently associated with the presence of PS.We immunostained synovial biopsies from 23 pts with PS (13 pts) or non-PS (10 pts). PS was significantly associated with higher density of vessels (p=0.042) and a strong trend to a higher density of B, T, Mast cells and macrophages (figure 1). Significantly higher serum levels of angiogenic (Activin A, bFGF, IL18, IL20, PIGF, SDF-1 and VEGF-D) and pro-inflammatory (IL23) cytokines were found in patients with PS (figure 2).Conclusion:The presence of “proliferative Synovitis” was significantly associated with ACPA and erosive disease in patients with RA. PS pattern also was associated with higher density of synovial vessels and higher serum levels of angiogenic and inflammatory mediatorsTable .Total US pattern p valueN=205Proliferative (N=101)Non proliferative (N=104)Female, n (%)162 (79.4)79 (78.2)83 (80.6)0.57Age, mean (SD) years57.1 (± 14,1)56.3 (± 12.0)58.0 (± 15.9)0.40Current Smoker, n (%)47 (26.9)22 (25.6)25 (28.1)0.73Disease duration, mean (SD) months113.3 (± 105.7)127.7 (± 111.1)99.3 (± 99.3)0.05Erosion, n (%)108 (53.7)73 (72.3)35 (35.0)0.00ACPA, n (%)153 (75.4)89 (89)64 (62.1)0.00RF, n (%)99 (68.3)78 (78)63 (61.2)0.01DAS 28–CRP, mean (SD)2.55 (±1.03)2.66 (±1.04)2.44 (±1.02)0.17GC, n (%)99 (49.3)45 (45.5)54 (52.9)0.32cDMARDs, n (%)152 (75.6)81 (81.8)71 (69.6)0.05bDMARD, n (%)69 (34.3)35 (35.4)34 (33.3)0.76Total US score14.9 (± 11.5)18.8 (± 11.8)11.1 (± 9.9)0.00*ACPA anti-citrullinated protein antibodies, RF rheumatoid factor, DAS28-CRP Disease Activity Score 28-joint count, CRP C-reactive protein, GC glucocorticoids, bDMARD biological disease-modifying antirheumatic drugsDisclosure of Interests:Ana Belén Azuaga-Piñango: None declared, Beatriz Frade-Sosa: None declared, Roberto Gumucio: None declared, Katherine Cajiao: None declared, Andrea Cuervo: None declared, Raquel Celis: None declared, Jose A. Gómez-Puerta Speakers bureau: Abbvie, BMS, GSK, Lilly, Pfizer, Roche, Raimón Sanmartí Speakers bureau: Abbvie, Eli Lilly, BMS, Roche and Pfizer, Juan de Dios Cañete: None declared, Julio Ramirez: None declared