P058 S100 proteins effectively discriminate systemic lupus erythematosus patients from healthy controls, but are not associated with measures of disease activity

Introduction The S100 proteins are important regulators of diverse calcium-dependent cellular processes including growth regulation, migration and apoptosis. Dysregulated expression of multiple members of S100 family is a common feature of cancer and several autoimmune diseases. Objectives The aim of this study was to examine whether circulating levels of S100A4, S100A8/9 and S100A12 proteins could be useful as diagnostic or activity specific markers in systemic lupus erythematosus (SLE). Methods S100 plasma levels were measured by ELISA in a cohort study of 44 patients with SLE, 8 patients with incomplete SLE (iSLE) and 43 healthy controls (HCs). Disease activity was assessed using SLEDAI-2 K. We examined cross sectional associations between concentrations of S100 proteins and SLE status, SLEDAI-2 K scores, and levels of conventional biomarkers. Results Plasma levels of all analysed S100 proteins (S100A4, S100A8/9 and S100A12) were significantly higher in SLE patients compared to HCs (p Conclusions We demonstrate increased S100 proteins expression in SLE patients. Although they were not strongly associated with disease activity, S100 proteins and namely S100A4 could be proposed as a diagnostic biomarker for SLE. Acknowledgements MHCR for conceptual development of research organisation 00023728 and SVV 260 373. Disclosure of interest None declared