Urine proteome scans uncover total urinary protease PGDS SAP and SOD as potential markers of lupus nephritis

摘要

To identify potential biomarkers in immune-mediated nephritis, urine from mice subjected to an augmented passive model of anti-glomerular basement membrane-induced experimental nephritis was resolved using 2D-gels. The urinary proteome in these diseased mice was comprised of at least 71 different proteins. Using orthogonal assays, several of these molecules, including serum amyloid P, prostaglandin D synthase, superoxide dismutase, renin and total protease were validated to be elevated in the urine and kidneys of mice during anti-GBM disease, as well as in mice with spontaneously arising lupus nephritis. Among these, urinary protease was the only marker that appeared to be exclusively renal in origin, whereas the others were partly serum-derived. Longitudinal studies in murine lupus demonstrated that total urinary protease had better predictive value for histologically active nephritis (r = 0.78), compared to proteinuria (r = −0.04) or azotemia (r = 0.28), or the other markers examined, while urine SAP emerged as the single most predictive marker of histological GN. Collectively, these studies uncover total urinary protease, PGDS, SAP and SOD as novel biomarkers of anti-GBM disease and lupus nephritis, with stronger correlation to renal disease compared to currently employed biomarkers. These findings could have important diagnostic and prognostic ramifications in the management of these renal diatheses.