Application Of Urinary Proteome Analysis In Type 2 Diabetic Nephropathy

Objective To detect urinary proteomic profiling of patients with type 2 diabetes (T2DM) by using ProteinChip array technology, to search new potential biomarkers in patients with type 2 diabetic nephropathy (T2DN), to investigate the clinical value of ProteinChip array technology in early diagnosis of T2DN.Methods Early morning urine samples were obtained from T2DM with normoalbuminuria (Urinary albumin excretion rate:UAER<30mg/g Cr, DM group, n=30), microalbuminuria (30≤UAER≤300mg/g Cr, DN1 group, n=25), macroalbuminuria (UAER>300mg/g Cr, DN2 group, n=20) and sex-matched control group (n=20). Surface-enhanced laser desorption/ionization time of flight mass spectrometry (SELDI-TOF-MS) and H50 ProteinChip were used to detect the urinary proteomic patterns of the whole subjects. The protein peaks (m/z) of the experiment were analyzed by the Cancer Institute of ZheJiang University-Protein Chip Data Analysis System (ZUCI-PDAS, www.zlzx.net),which was designed by Yu Jiekai.Results Over 300 proteins or peptides from 1 to 80 kDa were obtained using ProteinChip. About 40 of them were differentiated between type 2 diabetic patients and control subjects. Then by analyzing the protein peaks according to albumin partition,16 proteins or peptides were significantly different, of which the m/z of 9 proteins or peptides decreased with increasing UAE, while 7 proteins/peptides increased including some known proteins such as al-microglobulin (M/Z:23413.44 Da),β2-microglobulin (M/Z:11745.96 Da), transferrin (M/Z:79176.55Da) and some unknowns, Four top-ranked peaks with m/z values of 2797.03,4545.77,4984.03 and 9083.71 Da were illustrated to be highly differentially expressed between DM and DN1 with a specificity of 96.7% and a sensitivity of 88%, as evaluated by leave-one-out cross-validation.Conclusions ProteinChip technology can be used to analyze urinary proteins in patients with type 2 diabetes and then further to effectively identify urine biomarkers. The urinary proteomic patterns are obviously differentially expressed between non-T2DN patients and early T2DN. The selected differentially-expressed low-molecular protein peaks may have clinical vaule in early warning, diagnosis and treatment of T2DN.