Ab0247 the role of autoimmunity on the relation between erosions and bone mineral density in rheumatoid arthritis: a clinical research

BackgroundRheumatoid arthritis (RA) is the most frequent chronic inflammatory rheumatism. It is characterized by peripheral articular destruction and it is well known that erosions are correlated with the presence and titer of anti-citrullinated peptide antibodies (ACPA)(1). RA is also known to be an independent factor of osteoporosis(2) and it has already been demonstrated that ACPA is associated with bone mineral density (BMD) at the hip and spine(3). The physiopathology of erosion and bone loss in RA is related to osteoclast activation via RANK-L pathway stimulation, that can possibly be lead by ACPA(4).ObjectivesOur aim was to determine if there is an association between local and systemic bone damage in RA, represented respectively by erosion and BMD, and whether it may be driven by ACPA and/or other autoimmunity-related antibodies.MethodsPatients followed in the Department of Rheumatology between January 2008 and May 2019 satisfied the 1987 ACR or 2010 ACR-EULAR criteria. To be included, they had to undergo radiographs and biology at intervals of less than 2 years from DXA. Bone mineral density (BMD) was evaluated in g/cm2 and by T-score at the hip on DXA. Erosions were evaluated by the modified Sharp/van der Heidje erosion score (SHSe) on radiographs and the presence and titers of ACPA, rheumatoid factor (RF) and anti-nuclear antibodies (ANAs) were recorded.ResultsA total of 149 patients met the inclusion criteria, represented by 75.8% of women. They had a mean age of 62 (SD 9.61) and a long median disease duration of 132 [60; 240] months. A total of 61.1% patients were ACPA positive, 79.9% were erosive and 10.7% had a hip or spine T-score ≤-2.5. A higher erosion score was associated with a lower BMD (R2: 0.049 and value: -0.222; p=0.009) and T-score (R2: 0.158 and value -0.397; p<0.0001) at the hip. ACPA status, but not titer, was associated with a higher erosion score (63.0 (53.2) vs. 45.5 (44.1) for ACPA – (p= 0.04)). ACPA titers were associated with lower BMD at the hip (value -0.216; p=0.01) but not with T-score. In linear regression, erosion and bone mineral density were still associated but this association does not seem to be driven by ACPA status or titer. RF and ANA did not demonstrate any role in this association.Figure 1.SHSe total score and associated variables in linear regressionConclusionWe have shown that erosions were associated with lower BMD and T-score at hip but also at spine. Nevertheless that relation does not seem to be driven by ACPA or other autoimmunity-related antibodies. However, the presence of ACPA or erosion should lead to osteoporosis assessment.References[1]Maddali Bongi S, Manetti R, Melchiorre D, Turchini S, Boccaccini P, Vanni L, et al. Anti-cyclic Citrullinated Peptide Antibodies are Highly Associated with Severe Bone Lesions in Rheumatoid Arthritis Anti-CCP and Bone Damage in RA. Autoimmunity. sept 2004;37(6‑7):495‑501.[2]Adami G, Saag KG. Osteoporosis Pathophysiology, Epidemiology, and Screening in Rheumatoid Arthritis. Curr Rheumatol Rep. juill 2019;21(7):34.[3]Tomizawa T, Ito H, Murata K, Hashimoto M, Tanaka M, Murakami K, et al. Distinct biomarkers for different bones in osteoporosis with rheumatoid arthritis. Arthritis Res Ther. déc 2019;21(1):174.[4]Harre U, Georgess D, Bang H, Bozec A, Axmann R, Ossipova E, et al. Induction of osteoclastogenesis and bone loss by human autoantibodies against citrullinated vimentin. J Clin Invest. 1 mai 2012;122(5):1791‑802.Disclosure of InterestsNone declared