Urinary proteomics of lupus nephritis

Abstract

Lupus nephritis (LN) is one of the common causes of chronic kidney disease, especially in Asian ethnic. The kidney biopsy score is currently the most important diagnostic and severity-determined biomarker. Inevitably, the non-invasive biomarker is interesting for diagnosis and prognosis of LN due to the risk of post-renal biopsy complications. Urine proteomics are the current interesting tools to enhance discovery of protein urinary biomarkers. In this study, we used 2-dimensional gel electrophoresis (2-DE) and identified the spot difference by electrospray/ liquid chromatography/ mass spectrometry technique (ESI/LC/MS) between urine of active and inactive LN patients. Sixteen proteins were quantitatively different. Zn-alpha2-glycoprotein (ZA2G) and prostaglandin H2 D-isomerase (PGDS) were validated by enzyme-linked immunosorbent assay in a large patient sample set. Urinary ZA2G was increased in both active LN and other glomerular diseases whereas PGDS was increased specifically in active LN. Urinary PGDS might be a good diagnostic and prognostic biomarker for active LN. Moveover, we have studied in patient after treatment with immunosuppressive medicine. Seven proteins were differentially expressed between groups. CD59 and A1M play an immunoprotective role. Further validation in a larger sample size is needed.