Decreased expression of circulating microRNA-126 in patients with type 2 diabetic nephropathy: A potential blood-based biomarker

Abstract

Circulating microRNAs (miRNAs) have been proposed as promising biomarkers for multiple diseases. miR-126 is reported to be associated with type 2 diabetes mellitus (T2D), diabetic nephropathy (DN) and end stage renal disease. The aim of this study was to investigate the expression of circulating miR-126 and to assess its potential as a blood-based biomarker for DN in T2D patients. In 52 patients with T2D without history of DN (with noromoalbuminuria), 50 patients with T2D and DN (29 with microalbuminuria and 21 with macroalbuminuria), and 50 non-diabetic healthy controls, the expression of circulating miR-126 in peripheral whole blood was evaluated by quantitative polymerase chain reaction. The expression levels of circulating miR-126 were significantly decreased in T2D patients and further decreased in DN patients compared with those in the controls. Multivariate logistic regression analysis confirmed the independent association of lower miR-126 levels with T2D [adjusted odds ratio (OR), 0.797; 95% confidence interval (CI), 0.613-0.960] and DN (adjusted OR, 0.513; 95% CI, 0.371-0.708). miR-126 levels were associated with the degree of albuminuria and showed significantly low expression in DN patients with microalbuminuria (adjusted OR, 0.781; 95% CI; 0.698-0.952) and further lower expression in DN patients with macroalbuminuria (adjusted OR, 0.433; 95% CI, 0.299-0.701), respectively compared with T2D patients with normoalbuminuria. miR-126 levels negatively correlated with albuminuria positively with glomerular filtration rate (P<0.05), and in addition, negatively correlated with fasting glucose, glycated hemoglobin, triglyceride and LDL (P<0.05). Stepwise multiple regression analysis identified albuminuria as a significant predictor of miR-126 (P<0.001). miR-126 in peripheral blood yielded area under the receiver operating characteristic curves of 0.854 (95% CI, 0.779-0.929) and 0.959 (95% CI, 0.916-1.000) in the differentiation of DN patients from T2D patients and DN patients from non-diabetic controls respectively. These data suggest that decreased expression of circulating miR-126 is associated with the development of DN in T2D patients, and may be a promising blood-based biomarker for DN risk estimation.

Keywords: biomarker; circulating miRNAs; diabetic nephropathy; miR-126; type 2 diabetes mellitus.

Figure 1.

Expression of circulating miR-126 in T2D patients, DN patients and healthy controls. Expression levels of circulating miR-126 were quantified by quantitative polymerase chain reaction in the peripheral whole blood of T2D patients with normoalbuminuria (n=52), DN patients with microabuminuria or macroalbuminuria (n=50) and non-diabetic healthy control individuals (n=50). Relative expression levels of miR-126 normalized to those of RNU6B are expressed as the mean ± standard deviation (SD). *P<0.05 vs. the control group, ^†P<0.05 vs. the T2D group.

Figure 2.

Association of circulating miR-126 levels with the degree of albuminuria. The association of circulating miR-126 expression levels with the degree of albuminuria was determined in a sub-analysis in T2D patients with normoalbuminuria (n=52), DN patients with microalbuminuria (n=29) and DN patients with macroalbuminuria (n=21) to determine the association between circulating miR-126 expression levels and the development of DN. *P<0.05 vs. the normoalbuminuria group, ^†P<0.05 vs. the microalbuminuria group.

Figure 3.

Correlation between circulating miR-126 and renal function parameters and other clinical variables. Pearson's coefficient correlation analysis was undertaken in patients with DN to determine the correlation between circulating miR-126 levels and albuminuria, eGFR, FG, HbA1c, triglyceride and LDL. (A) Circulating miR-126 negatively correlated with albuminuria. (B) Circulating miR-126 positively correlated with eGFR. (C) Circulating miR-126 negatively correlated with FG. (D) Circulating miR-126 negatively correlated with HbA1c. (E) Circulating miR-126 negatively correlated with triglyceride. (F) Circulating miR-126 negatively correlated with LDL.

Figure 4.

Receiver operating characteristic (ROC) curves of circulating miR-126. The receiver operating characteristic (ROC) analysis was used to assess the biomarker potential of miR-126, and the area under the curve (AUC) was reported. (A) MiR-126 differentiated between DN patients and T2D patients (AUC 0.854; 95% CI 0.779–0.929). (B) MiR-126 differentiated between DN patients and healthy controls (AUC 0.959; 95% CI 0.916–1.000).