Diagnostic Urinary Proteome Profile for Immunoglobulin A Nephropathy

Immunoglobulin A (IgA) nephropathy, the most common type of glomerulonephritis, is only diagnosed by invasive kidney biopsy. Urine proteome panel might help in noninvasive diagnosis and also better understanding of pathogenesis of IgA nephropathy. Second mid-stream urine samples of 13 patients with biopsy-proven IgA nephropathy and 8 healthy controls were investigated by means of nanoscale liquid chromatography tandem mass spectrometry. Multivariate analysis of quantified label-free proteins was performed by the principal component analysis and partial least squares models. A total number of 493 unique proteins were quantified by nanoscale liquid chromatography tandem mass spectrometry, of which 46 proteins were considered as putative biomarkers of IgA nephropathy, after multivariate analysis and additional filter criterion and comparing the patients and the controls. Some of the significant differentially expressed proteins were CD44, glycoprotein 2, vasorin, epidermal growth factor, CLM9, protocadherin, utreoglobin, dipeptidyl peptidase IV, NHL repeat-containing protein 3, and SLAM family member 5. These proteins were related to various involved pathogenic pathways of inflammatory response and complement system. This proteome profile could be utilized in the diagnosis of IgA nephropathy. In addition, providing a noninvasive diagnostic tool, it may shed light on the pathogenesis of IgA nephropathy.