Urine miRNAs: Potential biomarkers for monitoring progression of early stages of diabetic nephropathy

With a steep increase in the incidence of type 1 and 2 diabetes globally, diabetic nephropathy (DN) has now become the leading cause of renal failure in the world. There are no suitable biomarkers for the diagnosis of early stages of DN. In recent years, tremendous efforts are being made worldwide to delineate the role of micro RNAs in the pathogenesis of DN. Circulating miRNAs in serum, plasma, urine and other body fluids, which reflect a response to various pathophysiological stresses, are being investigated in the context of diabetic nephropathy. Delineation of the changes in miRNA levels in patients with DN may lead to a better understanding of the progression of the disease. We present here an exhaustive survey of the miRNA literature, highlighting various studies performed over the last decade. The aim is to assess if changes in various miRNAs could correlate with the progression of diabetic nephropathy. Based on the survey, we found that miRNA-377, miRNA-192, miRNA-216/217 and miRNA-144 are increased in body fluids of patients with DN, while miRNA-21 and miRNA-375 are decreased. Overall, there are a very few miRNAs that are kidney specific, and although significant differences were observed in the urinary excretion of certain miRNAs, they were not correlative to their levels in the blood or plasma. Thus, it is completely plausible that urine-specific miRNAs could serve as novel biomarkers for the diagnosis of early stages of diabetic nephropathy.