THE UTILITY OF URINARY EXTRACELLULAR VESICLES IN DIAGNOSIS AND PROGNOSIS OF KIDNEY DISEASE

Abstract

Urinary extracellular vesicles (EVs) are an attractive resource for biomarker discovery.

In this thesis we hypothesize that unique urine EV protein signatures are useful in two contexts: (i) they may aid in the differentiation of immunologic from non-immunologic glomerular disease; and (ii) they may be functionally associated with rapidly declining kidney function in type 2 diabetic kidney disease (DKD) patients, and may serve as clinically useful biomarkers and reveal pathogenic pathways.

We found that ultracentrifugation was the most optimal method for EV isolation for purposes of downstream proteomic interrogation, whilst evaluating other comparable methods. Protein signatures in urine EVs related to carbohydrate metabolism, the transforming growth factor – beta (TGF-) pathway and integrin/epithelial-mesenchymal transition characterized the diagnostic group of pediatric IgAN in the context of the clinical conundrum of hematuria with proteinuria, while miRNA was not useful for differential diagnosis. Complement was upregulated in the urine EVs of diabetic nephropathy patients with rapid renal function decline, and corroborated with complement transcripts in their kidney biopsies, demonstrating the power of an integrative biology approach. We explored an algorithmic classifier approach which performed satisfactorily in assigning the correct decliner classes to DKD patients.