Expression Level of Circulating Cell Free miR-155 Gene in Serum of Patients with Diabetic Nephropathy

Background: Diabetic nephropathy (DN) is the leading cause of end-stage renal disease worldwide. Several factors are known to contribute to the development and progression of diabetic nephropathy. Different microRNAs have been shown to contribute in the pathogenesis of DN. This study, aimed to evaluate the expression level of circulating miR-155 in patients with diabetic nephropathy. Methods: In this case-control study, 83 diabetic patients and normal subjects were evaluated in four groups of normal healthy subjects without diabetes and nephropathy, diabetes without nephropathy, diabetes with microalbuminuria, and diabetes with macroalbuminuria. After RNA extraction from serum and cDNA synthesis, the expression of circulating miR-155 was evaluated by quantitative polymerase chain reaction (qPCR). Results: Expression level of cell-free miR-155 was significantly lower in diabetics compared to the normal healthy controls (p < 0.05). However, no significant difference was found in miR-155 expression level between different diabetes groups with different conditions of kidney function. Furthermore, we detected a significant negative correlation between cell-free miR-155 expression and GFR only in patients with microalbuminuria (r = -0.70, p = 0.001). Conclusions: It seems that miR-155 can discriminate diabetic and nondiabetic status, but is not an appropriate biomarker for tracking of macroalbuminuria.