Urinary Exosomal mRNA of WT1 as Diagnostic and Prognostic Biomarker for Diabetic Nephropathy

Diabetic nephropathy (DN) is the major cause of end-stage renal failure and is associated with increased morbidity and mortality as compared to other causes of renal disease. Albuminuria is often the first clinical indicator of the presence of DN. However, albuminuria or proteinuria is a common symptom in patients with various renal disorders. Therefore, specific biomarkers for the diagnosis of DN are required. A primary hallmark of DN is the progressive damage and death of glomerular podocytes, resulting in the leaking of proteins into the urine. Urinary exosomes released by podocytes are microvesicles containing information of the originated cells. Podocyte-derived signal transduction factors (PDSTFs) are good candidates to assess podocyte injuries. The profile of PDSTFs in urinary exosomes from patients with DN is different from that from patients with minimal change nehrotic syndrome. In addition, PDSTFs molecules in exosomes were derived from primary murine podocytes under high glucose conditions. Among PDSTFs in urinary exosomes, Wilms tumor 1 (WT1) levels reflected damage of diabetic glomeruli in the patients. Urinary exosomal WT1 can predict the decline in eGFR for the following several years. In conclusion, urinary exosomal WT1 is a useful biomarker to improve risk stratification in patients with DN.