Abstract 402: Increased Levels of Extracellular DNA in Plasma Are Associated With Diabetic Microangiopathy

Abstract

Introduction: Diabetic hyperglycemia leads to severe glycation of blood and vascular components. Glycation end products are toxic and linked to chronic inflammation and vascular dysfunction, particularly in the microcirculation. Hyperglycemia mediates endothelial apoptosis and the formation of neutrophil extracellular traps (NETs), with genomic DNA released into the blood stream. Circulating DNA (cirDNA) levels may thus testify for vascular injury in type 2 diabetes. Patients and methods: Blood from type 2 diabetic patients and healthy volunteers was collected after signed and informed consent (collection Diabelyse DC-2011-1480). All volunteers were more than four months away from acute cardiovascular events or infection, free from neoplasia, coagulopathy or hemoglobinopathy, and had not smoked, consumed alcohol or coffee within 24 hours. Platelet-free plasma (PFP) was prepared within 4 hours, frozen and only thawed once. We quantified total extracellular DNA in plasma by fluorimetry after labeling with the intercalating probe Sytox Green™. Results: 65 diabetic subjects were included (age= 62+/-14 yo; sex ratio= 0.86; BMI= 32.5+/-8.7; HbA1C levels= 8,4+/-1,9%). 58,1% of diabetic patients were treated with insulin. 28,6% patients presented macroangiopathy and 67,7% microangiopathy, including 57,6% with retinopathy (21,7% treated by laser) and 58,1% with nephropathy. 25,9% patients displayed microalbuminuria, 22,4% proteinuria and 35,4% renal insufficiency (creatinin clearance <60 ml/min/1,73m 2 ). 52 matched non-diabetic volunteers were included. Levels of cirDNA were significantly elevated in diabetic patients with microangiopathy (27,9+/-13,9 RFU) versus other patients (19,4+/-6,1 RFU; p=0,04), or healthy volunteers (15.6+/-5.2 ; p=3.10-7). We noted a 50% increase in cirDNA specific to retinopathy (p=0.026), and a trend associating elevated cirDNA with nephropathy (+40%, p=0.060), microalbuminuria or proteinuria (+45%, p=0.060). There was no change in cirDNA during renal insufficiency (p=0.63). Conclusion: CirDNA in plasma is particularly easy to quantify by simple and robust assays. Its measure could contribute to the early and specific diagnostic of microvascular injury in diabetic patients.