Study of the Role of Soluble Forms of RAGE (sRAGE/esRAGE) as Diagnostic and Prognostic Biomarkers of Systemic Lupus Erythematosus.

Expected results : The investigators expect a correlation between serum sRAGE, esRAGE and activity of SLE and the presence of visceral involvement. Furthermore this study will allow us to analyze for the first time in a lupus population, the correlation between soluble forms of RAGE (esRAGE, sRAGE) and cytokines and molecules involved in lupus visceral involvement as IL-6, IL-1α, IFN-γ, sICAM-1 and sVCAM-1. Completion of our project, will allow better understanding of the role of RAGE and RAGE ligand in SLE activity and will provide rationale for prospective study. Future perspectives will include assessment of the risk-benefit for the use of anti-RAGE strategies or recombinant sRAGE/esRAGE molecules as adjuvant treatment for SLE. Study Design : the investigators designed an retrospective, analytic, transversal, mulitcentric study. the investigators would like to use the serum and the clinical information collected in "Lupus BioBanque du Rhin Supérieur" (LBBR UF 9882) to measure soluble forms of RAGE, RAGE-ligands, cytokines, and sICAM and sVCAM. The investigators would like to include 150 patients in this study. Aim 1: The main objective of this study is to investigate the association between Systemic Lupus Erythematosus (SLE) activity as measured by the SLEDAI score and serum concentrations of sRAGE and esRAGE. Aim 2 : The study of the correlation between the activity of other activity markers of SLE and soluble forms of RAGE : 1. the concentration of RAGE ligands (AGEs like CML, pentosidine and MG-H1) and soluble forms of RAGE (esRAGE, sRAGE) 2. the cytokine profile (IL-6, IL-1α, IFN-γ) and soluble forms of RAGE (esRAGE, sRAGE) 3. The concentrations of sICAM-1 and sVCAM-1 and soluble forms of RAGE (esRAGE, sRAGE) Methods : Inclusion criteria are : * the LBBR inclusion criteria * and Absence of immunomodulatory treatment, * and preserved renal function (MDRD\> 60ml/min). Exclusion criteria are : * renal failure defined by MDRD clearance \< 60 mL/min/m2, * or neoplasia, * or diabetes, * or other autoimmune disease, * or current immunosuppressive treatments. Data collection : About 500 μl of serum will be necessary for each patients to make all measurements. Mass spectrometry will be used for measurement of RAGE ligands (Advanced glycation end products such as CML, pentosidine and MG-H1). Commercially available ELISA kits will be used for measurement of sRAGE, esRAGE, sVCAM1. Flow Cytometry will be used for measurement of cytokines (IL-6, IL-1a, IFN-y) and sICAM1.