Abstract: TH-PO685

Lysosomal Enzymes Dominate the Urinary Proteome of Adolescents with Early Type 1 Diabetes

Session Information

Category: Diabetes

  • 501 Diabetes Mellitus and Obesity: Basic - Experimental

Authors

  • Van, Julie Anh Dung, University of Toronto, Toronto, Ontario, Canada
  • Hauschild, Anne-Christin, Princes Margaret Cancer Center, Toronto, Ontario, Ontario, Canada
  • Batruch, Ihor, Mount Sinai Hospital, Toronto, Ontario, Canada
  • Diamandis, Eleftherios P., Mount Sinai Hospital and University Health Network, Toronto, Alberta, Canada
  • Scholey, James W., University of Toronto, Toronto, Ontario, Canada
  • Konvalinka, Ana, University Health Network, University of Toronto, Toronto, Ontario, Canada
Background

Diabetes is the leading cause of kidney disease worldwide. Microalbuminuria has been recognized as one of the earliest indicators of renal damage in diabetes. However, maladaptive changes have been described in the diabetic kidney long before the onset of microalbuminuria, in the form of renal hyperfiltration and hypertrophy. Our aim is to examine the urinary proteome of adolescents with early type 1 diabetes and to examine the biological processes and pathways underlying early changes in the diabetic kidney.

Methods

We collected second-morning, midstream urines from 15 cases with type 1 diabetes and 15 age- and sex-matched controls. Urine volumes normalized to creatinine were subjected to 10kDa ultrafiltration to isolate proteins. Proteins (200 ug) were digested with trypsin, fractionated, and analyzed on Q-Exactive mass spectrometer. MaxQuant software was used for peptide/protein identification and label-free quantification. Pathway Data Integration Portal (pathDIP), an annotated database of signaling cascades and core pathways, was used to examine the significantly altered pathways in early type 1 diabetes.

Results

A total of 576 proteins were consistently detected across all thirty urine samples, representing roughly 25% of our total urinary proteome (n = 2313). Of these, 34 were differentially excreted between groups (Benjamini-Hochberg FDR, q < 0.05): seven were decreased in diabetes (e.g., ACY1, TIMP1, FSTL1), and 27 were increased (e.g., LRG1, MAN2B1, NAGA). More than half of these differentially excreted proteins were lysosomal enzymes, and the dominant pathways and processes associated with these lysosomal enzymes include “hydrolase activity”, “glycosaminoglycan degradation”, and “spingolipid metabolism”.

Conclusion

Differences in the urinary proteome can be detected prior to the onset of microalbuminuria in adolescents with type 1 diabetes, compared to healthy controls. Enzymes from lysosomal compartment were overrepresented in diabetes, suggesting that lysosomal protease activity is an early response of the kidney to hyperglycemia.