Comparative proteomic analysis of urine and laser microdissected glomeruli in IgA nephropathy

Abstract

The purpose of the present study was to identify the differential proteins that synchronously change in urine and glomeruli and could be used to monitor glomerular lesions of IgA nephropathy (IgAN). The proteomes of urine and glomeruli from four IgAN patients who were graded III/IV according to the grading system of Lee et al. were compared to the urine proteomes of four healthy volunteers and the glomeruli proteomes of adjacent normal tissue from four patients with renal tumors, respectively. Western blot, enzyme-linked immunosorbent assay and immunofluorescence assay were applied to verify the results of the proteomic analysis. In the proteomic analysis of urine from IgAN patients and healthy volunteers, 714 proteins were identified, with 246 proteins identified as differential proteins. In the proteomic analysis of glomeruli from renal biopsy tissue of IgAN patients and from adjacent normal tissue of patients with renal tumors, 161 proteins were identified altogether, and 20 proteins of these were recognized as differential proteins. After comparatively analyzing the differential proteins identified in the urine and glomeruli, five synchronously changed differential proteins were found: complement C9, Ig kappa chain C region and three cytoskeleton proteins. In summary, our findings indicate that certain immunological indices in urine appear to be associated with glomerular lesions of IgAN.

Proteomics of human glomerulonephritis by laser microdissection and liquid chromatography‐tandem mass spectrometry

“…Next, we examined adequate amounts of the samples required for LC‐MS/MS. In previous reports, a minimum of 4 to 100 glomeruli had to be dissected from 10‐μm‐thick sections. We think that this number depends on the purpose of the study, the amount of the targeted protein, and the sensitivity of mass spectrometer used.…”

“…Application of this novel technique to the diagnosis of glomerulonephritis has just begun. To date, IgA nephropathy (IgAN) has been analysed in a few studies, with a focus mainly on deposited immunoglobulin and complements . In our study, we analysed the glomerular proteomics of IgAN and membranous nephropathy (MN) by LMD and LC‐MS/MS and we compared our findings with those for normal glomeruli obtained at biopsies from kidney transplant donors.…”

“…To date, IgA nephropathy (IgAN) has been analysed in a few studies, with a focus mainly on deposited immunoglobulin and complements. 6,7 In our study, we analysed the glomerular proteomics of IgAN and membranous nephropathy (MN) by LMD and LC-MS/MS and we compared our findings with those for normal glomeruli obtained at biopsies from kidney transplant donors. Moreover, we investigated the significance of the detected molecules with regard to the diagnosis and pathogenesis of glomerular diseases.…”

Itraq-Based Comparative Proteomics Analysis Reveals Specific Urinary Biomarkers for Various Kidney Diseases

“…In the progression of DN, the decrease in some urinary proteins is presumably associated with impaired secretory function of other organs, such as a reduced excretion of pancreatic amylase and deoxyribonuclease I [31]. The DEPs identified in the IgAN group using iTRAQ appear to be involved in several molecular functions including responses to external stimuli and immune responses, as well as multiple signalling transduction pathways such as cytokine-cytokine receptor interaction and ubiquitin mediated proteolysis [32]. For the first time, we performed functional and KEGG pathway analysis of identified DEPs among patients with AKI, AKI + CKD, diabetic CKD and nondiabetic CKD with or without IgAN.…”

iTRAQ-based comparative proteomics analysis reveals specific urinary biomarkers for various kidney diseases

“…In the progression of DN, the decrease in some urinary proteins is presumably associated with impaired secretory function of other organs, such as a reduced excretion of pancreatic amylase and deoxyribonuclease I(28). The DEPs identified in the IgAN group using iTRAQ appear to be involved in several molecular functions including responses to external stimuli and immune responses, as well as multiple signalling transduction pathways such as cytokine-cytokine receptor interaction and ubiquitin mediated proteolysis(29). For the first time, we performed functional and KEGG pathway analysis of identified DEPs among patients with AKI, AKI+CKD, diabetic CKD, and non-diabetic CKD with or without IgAN.…”