title: Changes in urine proteome accompanying diabetic nephropathy progression.
abstract: BACKGROUND
  Owing to the prevalence of type 2 diabetes, diabetic kidney disease (DKD) becomes the major cause of end-stage renal disease. The current markers of diabetic nephropathy are based on albuminuria and clinical signs of retinopathy. Sensitive and specific noninvasive diagnostic tools, unbiased by the presence of comorbidities, are needed, especially to detect the early stages of diabetic complications.
  
  
  OBJECTIVE
  The aim of the study was to analyze changes in urinary protein excretion based on the stage of DKD using quantitative proteomics.
  
  
  METHODS
  A total of 27 healthy controls were age- and sex-matched to 72 diabetes patients classified into 3 groups: no signs of retinopathy or nephropathy (n = 33), retinopathy but no microalbuminuria (n = 15), and diabetic nephropathy (DN) based on overt albuminuria or microalbuminuria with retinopathy (n = 24). To assess the intergroup differences, samples were partially pooled, tagged using 8-plex iTRAQ reagents, and the resulting peptide mixture was resolved by isoelectrofocusing. The obtained fractions were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Data were analyzed using the MASCOT software and dedicated in-house proteomic data analysis programs.
  
  
  RESULTS
  The changes in the urine proteome following DKD progression involved some known protein markers of DN and several other proteins. Decreased levels of some proteins are presumably related to impaired secretory function of other organs affected by diabetes. In particular, a diminished excretion of pancreatic amylase and deoxyribonuclease I suggested exocrine pancreatic insufficiency (EPI), coexisting with type 2 diabetes.
  
  
  CONCLUSIONS
  A decrease in the urinary excretion of some pancreatic enzymes suggests EPI associated with diabetes. This hypothesis is yet to be verified; nevertheless, renal and extrarenal confounders must be considered when interpreting the results of quantitative urinary proteomics.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Lewandowicz
authors.forename: Magdalena
authors.initials: M
authors.lastname: Bakun
authors.forename: Rafał
authors.initials: R
authors.lastname: Kohutnicki
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Fabijańska
authors.forename: Michał
authors.initials: M
authors.lastname: Kistowski
authors.forename: Jacek
authors.initials: J
authors.lastname: Imiela
authors.forename: Michał
authors.initials: M
authors.lastname: Dadlez
mesh_terms: D000328:Adult; D000368:Aged; D000419:Albuminuria / Q000503:physiopathology / Q000652:urine; D015415:Biomarkers / Q000652:urine*; D003924:Diabetes Mellitus, Type 2 / Q000150:complications* / Q000652:urine; D003928:Diabetic Nephropathies / Q000209:etiology* / Q000503:physiopathology / Q000652:urine*; D003930:Diabetic Retinopathy / Q000503:physiopathology / Q000652:urine*; D018450:Disease Progression; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000209:etiology* / Q000503:physiopathology / Q000652:urine*; D008297:Male; D008875:Middle Aged; D020543:Proteome; D040901:Proteomics; D053719:Tandem Mass Spectrometry
chemical_list: D015415:Biomarkers; D020543:Proteome