THU0344 A PILOT STUDY ASSESSING THE EFFECT OF AIR POLLUTION ON EXTRACELLULAR VESICLES IN SYSTEMIC SCLEROSIS

Background Systemic sclerosis (SSc) is a severe autoimmune disease characterized by a progressive multi-organ fibrosis. The identification of specific diagnostic and prognostic biomarkers remains an unmet need. Over the past few years, it has been suggested that extracellular vescicles (EVs) and environmental toxicants, such as particulate matter (PM), may have an important role in the pathogenesis of autoimmune diseases. At present, no data are available on the impact of PM exposure on EVs from patients with SSc. Objectives Our aim was to evaluate the effects of PM with aerodynamic diameter ≤ 10 μm (PM10) and ≤ 2.5 μm (PM2.5) on EVs in SSc and osteoarthritis (OA) as control. Methods Plasma EVs were analyzed by Nanosight and flow cytometry after labeling with the following markers: CD14 (monocyte), CD61 (platelet), CD25 (T-reg), human endogenous retrovirus w (HERV-w), human leukocyte antigen G (HLA-G). Demographic and clinical data were collected for each patient. Plasma EV concentrations were measured in SSc and OA patients and were analyzed by generalized linear regression models. Daily PM concentrations, estimated by Regional Environmental Protection Agency at municipality resolution, were used to assign short-term exposure (mean of the 7 days preceding the evaluation) to each study subjects. Results 12 consecutive patients with limited cutaneous SSc (11 female, median age 66.8, median disease duration 12.3, 7 anti-centromere positive, median mRSS 3.5) and 12 patients with OA (median age 67.1, median disease duration 9.3, 8 female) were enrolled. The increase of PM2.5 led to a decrease of HERV-w+ microvesicles (MV) in both SSc (β=-0. 10; p=0. 01) and OA (β=-0. 09; p=0. 01) and of HLA-G+ (β=-0.11; p Conclusion In our study, limited cutaneous SSc showed different EVs concentrations from controls: SSc tends to have less exosomes and more MV than OA. Moreover, environmental stimuli (e.g. PM exposure) are confirmed to be able to influence HERV-w+ MV release both in SSc and controls. Finally, in SSc patients PM exposure could significantly alter the release of HLA-G+ MV that has been correlated to the process of self-tolerance maintenance. Further studies are required to fully unlock the role of PM and EVs in SSc. Disclosure of Interests None declared