FRI0354 Urine metabolomic fingerprint as diagnostic biomarker for lupus nephritis

Background Lupus nephritis (LN) represents the main prognostic factor for worsening in systemic lupus erythematosus (LES).1 The relevant classes of LN –due to the need of treatment- are the proliferative (III, IV, III/IV+V) and membranous (V). Objectives The aim of the study was to find a urinary metabolomic fingerprint to diagnose proliferative and/or membranous LN. Methods Cross-sectional study. Inclusion criteria: lupus patients with and without clinical significant lupus nephritis (classes III, IV, V and mixed classes). Urine samples were screened for metabolites using gas chromatography mass spectrometry (coupled with electronic nose). Statistical analysis: principal component analysis (PCA), and for the selection of the metabolites we used Random Forest. Results We included 29 lupus patients, 11 with LN. The median SLEDAI score in LN patients was of 13 vs. 3 in those without NL (p The variance explained using the first two principal components was 80%. With random forest we selected, 2 nonanone, as the metabolite with the best diagnostic accuracy, (sensitivity of 0.87 and specificity of 0.93) of proliferative LN. Obtaining the ratio of 2-bromopropane/2-nonanone, the diagnostic accuracy improved, with a positive likelihood ratio (LR) of 14 and a negative LR of 0.1(AUC 90%). Metabolic pathways involved in LN were: methane, glycolysis, pyruvate and glycerophospholipid pathways. Conclusions We identified a urinary metabolomic fingerprint that involved several metabolic pathways; 2-nonanone and the ratio of 2- bromopropane/2- nonanone had the best diagnostic accuracy in our study. Reference [1] Mok CC, et al. Arthritis Rheum2013;5:2154–2160. Disclosure of Interest None declared