AB0087 AUTOANTIBODIES DIRECTED AGAINST HOMOCYSTEINYLATED ALPHA 1 ANTITRYPSIN AS A POTENTIAL NEW BIOMARKER FOR ARTHRITIS IN PATIENTS AFFECTED BY SYSTEMIC LUPUS ERYTHEMATOSUS
Authors: F. Natalucci, F. Ceccarelli, T. Colasanti, G. Olivieri, A. I. Celia, C. Barbati, M. Speziali, F. Ucci, C. Pirone, C. Ciancarella, F. R. Spinelli, C. Alessandri, F. Conti
Journal: Annals of the Rheumatic Diseases (2021)

Background: Joint involvement represents one of the most frequent features in patients affected by Systemic Lupus Erythematosus (SLE). This manifestation is characterized by a great heterogeneity in phenotype and severity: the application of more sensitive imaging techniques identified an erosive damage in about 25% of patients (1). This damage has been associated with autoantibodies, such as anti-citrullinated (ACPA) and anti-carbamylated proteins (antiCarP), previously identified in patients Rheumatoid Arthritis (RA) patients. Recently, homocysteinylated alpha 1 antitrypsin (Hcy-1A1AT) has been identified as a new antigenic target of autoantibodies in seronegative RA patients: in detail, anti-homocysteinylated alpha 1 antitrypsin (anti – HATA) antibodies have been identified in 75.7% of patients (2). Objectives: In the present study, we aimed at determining the prevalence of anti – HATA in a cohort of SLE patients. Methods: We evaluated patients affected by SLE according to the 1997 ACR criteria. Demographic, clinical, and laboratory data were collected in a standardized computerized electronically filled form. Each subject underwent peripheral blood sample collection. Hcy-A1AT was obtained by in vitro modification of native A1AT and used as antigens by ELISA to test the presence of anti–HATA in sera obtained from enrolled subjects. Finally, we investigated the presence of ACPA and Rheumatoid Factor (RF) commercial ELISA kits and of anti-CarP (home-made ELISA) by a home-made ELISA in SLE patients’ sera. As control, we enrolled 40 patients affected by Osteoarthritis (OA) and 41 healthy subjects (HS). Results: The present analysis included 88 SLE patients (M/F 6/82 median age 47 years (IQR 17), median disease duration 156 months (IQR 180). Joint involvement was observed in 75 SLE patients (85.2%): in detail, 65 patients referred arthritis and the remaining 10 inflammatory arthralgias. We identified the presence of anti–HATA IgG in 38 SLE patients (43.2%). This prevalence was significantly higher in comparison with OA and HS subjects [15.0% (p&lt;0.001) and 0% (p&lt;0.0001), respectively; Figure 1A]. Focusing on the SLE cohort, no differences were observed between patients with and without joint involvement in anti–HATA IgG prevalence (41.3% versus 34.7%, respectively; p=0.34). However considering SLE patients according to the presence of arthralgia and arthritis, the prevalence of anti-HATA was significantly higher in patients with arthritis in comparison with those patients with arthralgias (46.1% versus 11.1%, p=0.02; figure 1B). Finally, no significant association between anti-HATA and the other tested autoantibodies (RF, ACPA, anti-CarP) was found. Conclusion: We evaluated the prevalence of anti-HATA in a cohort of SLE patients. The prevalence of these autoantibodies was significantly higher in SLE patients than in OA patients and in HS. The association with arthritis suggests a possible role for anti-HATA as biomarkers of SLE-related joint involvement. References: [1]Ceccarelli F. Perricone C. Cipriano E. et al. Joint involvement in systemic lupus erythematosus: From pathogenesis to clinical assessment. Seminar in Arthritis and Rheumatism, 47(1), 53 – 64. [2]Colasanti T. Sabatinelli D. Mancone et al. Homocysteinylated alpha 1 antitrypsin as an antigenic target of autoantibodies in seronegative rheumatoid arthritis patients. Journal of Autoimmunity 2020 Sep;113:102470. Disclosure of Interests: None declared