OBJECTIVETo study and identify the protein markers in the urine of children with steroid-sensitive (SSNS) and steroid-resistant nephrotic syndrome(SRNS).

METHODSTotal urinary proteins were extracted from children with SSNS before and after steroid therapy, SRNS, and healthy children (n=5 in each group). Urinary proteins were separated by immobilized pH gradient based on two-dimensional gel electrophoresis (2-DE). The silver-stained 2-DE gels were scanned with digital Image Scanner and analyzed with Image Master 2-DE Elite 3.01 software. Peptide mass fingerprint (PMF) of differential protein spots was obtained with MALDI-TOF-MS. Proteins were identified by Mascot software based on NCBI protein database.

RESULTSThere were 66 spots with different expression of protein between SRNS children and SSNS children before steroid therapy, and 24 spots and 27 spots only occurred in SRNS children and SSNS children before steroid therapy, respectively. There were 75 spots with different expression of protein between SSNS children after steroid therapy and healthy controls, and 11 spots only occurred in SSNS children after steroid therapy. Eighteen protein spots with different expression (6 spots in each nephrotic group) were chose and analyzed by MALDI-TOF-MS, and 9 types of proteins were identified.

CONCLUSIONSNine types of urinary proteins with different expression (6 spots in each nephrotic group) were identified between SRNS and SSNS children, and they might be the biomarkers for SRNS or SSNS.