MicroRNAs from urinary extracellular vesicles are non-invasive early biomarkers of diabetic nephropathy in type 2 diabetes patients with the 'Asian Indian phenotype'.

AIMS: MicroRNAs (miRNAs) from extracellular vesicles (EVs) have been proposed as promising biomarkers for a number of diseases. In this study, their potential as urine-based biomarkers of diabetic nephropathy (DN) was assessed. METHODS: MiRNAs were profiled in urinary EVs from 160 fasting subjects with normal glucose tolerance (NGT) and in T2DM patients with either microalbumininuria (MIC) or macroalbuminuria (MAC). RESULTS: A total of 73 miRNAs detected in urinary EVs (NGT) were predicted to target important functions for kidney homoeostasis, thereby validating their use as indicators of kidney dysfunction. Indeed, a urinary EV miRNA signature was found to comprise increased levels of let-7i-3p, miR-24-3p and miR-27b-3p, and decreased levels of miR-15b-5p, to identify patients with MIC. ROC curve analysis confirmed this ability to identify MIC in normo-albuminuria T2DM (T2DM-NA) patients and to differentiate between MAC and T2DM patients. These miRNAs were also predicted to target protein networks involved in the Wnt/ß-catenin signalling cascade, activin receptor signalling and cell differentiation/proliferation, and correlated with eGRF, HbA1c, serum creatinine, urea, albumin and blood pressure. Concentrations of miR-30a-5p were specifically modified in urinary EVs from patients with MAC, but not MIC, suggesting that miR-30a-5p could be related to severe kidney damage. CONCLUSION: Urinary EV miRNAs correlate with the degree of MIC. As they are also thought to regulate pathways that are targets of pharmacological agents to prevent DN (reticulum stress, activin receptors), they may also serve as non-invasive 'liquid biopsies' to stratify patients at risk of developing MAC and to monitor treatment efficacy.

High-fructose diet is as detrimental as high-fat diet in the induction of insulin resistance and diabetes mediated by hepatic/pancreatic endoplasmic reticulum (ER) stress.

In the context of high human consumption of fructose diets, there is an imperative need to understand how dietary fructose intake influence cellular and molecular mechanisms and thereby affect ß-cell dysfunction and insulin resistance. While evidence exists for a relationship between high-fat-induced insulin resistance and metabolic disorders, there is lack of studies in relation to high-fructose diet. Therefore, we attempted to study the effect of different diets viz., high-fat diet (HFD), high-fructose diet (HFS), and a combination (HFS + HFD) diet on glucose homeostasis and insulin sensitivity in male Wistar rats compared to control animals fed with normal pellet diet. Investigations include oral glucose tolerance test, insulin tolerance test, histopathology by H&E and Masson's trichrome staining, mRNA expression by real-time PCR, protein expression by Western blot, and caspase-3 activity by colorimetry. Rats subjected to high-fat/fructose diets became glucose intolerant, insulin-resistant, and dyslipidemic. Compared to control animals, rats subjected to different combination of fat/fructose diets showed increased mRNA and protein expression of a battery of ER stress markers both in pancreas and liver. Transcription factors of ß-cell function (INSIG1, SREBP1c and PDX1) as well as hepatic gluconeogenesis (FOXO1 and PEPCK) were adversely affected in diet-induced insulin-resistant rats. The convergence of chronic ER stress towards apoptosis in pancreas/liver was also indicated by increased levels of CHOP mRNA & increased activity of both JNK and Caspase-3 in rats subjected to high-fat/fructose diets. Our study exposes the experimental support in that high-fructose diet is equally detrimental in causing metabolic disorders.

Impaired miR-146a expression links subclinical inflammation and insulin resistance in Type 2 diabetes.

Type 2 diabetes patients exhibit subclinical inflammation but the regulatory mechanisms are poorly understood. We sought to evaluate the role of miR-146a expression along with its downstream proinflammatory signals in relation to glycemic control and insulin resistance. Study subjects (n = 20 each) comprised of clinically well characterized Type 2 diabetes patients and control non-diabetic subjects. miRNA and mRNA expression levels were probed in peripheral blood mononuclear cells (PBMC) by Real-time RT-PCR and plasma levels of TNFα and IL-6 were measured by ELISA. The miR-146a expression levels were significantly decreased in PBMCs from patients with Type 2 diabetes compared to control subjects. Among the target genes of miR-146a, TRAF-6 mRNA expression was significantly increased in patients with Type 2 diabetes while there was no significant difference in the mRNA levels of IRAK1 in the study groups. In contrast, there were significantly increased levels of NFκB expression in patients with Type 2 diabetes. There was an increased trend in the levels of TNFα and IL-6 mRNA in patients with type 2 diabetes. While SOCS-3 mRNA levels increased, plasma TNFα and IL-6 levels were also significantly higher in patients with type 2 diabetes. miR-146a expression was negatively correlated to glycated hemoglobin, insulin resistance, TRAF6, and NFκB mRNA levels and circulatory levels of TNFα and IL-6. Reduced miR-146a levels are associated with insulin resistance, poor glycemic control, and several proinflammatory cytokine genes and circulatory levels of TNFα and IL-6 in Asian Indian Type 2 diabetic patients.