Study About Advanced Glycation End Products Involved In Endothelial To Mesenchymal Transdifferentiation

Background:Diabetes mellitus (DM) is a multifactorial disease and increased risk of micro and macro vascular complications which are the major causes of morbidity and mortality. The primary causal factor leading to the pathophysiologic alterations in the diabetic vasculature is chronic exposure to high blood glucose level. Under hyperglycemic conditions, glucose and other reducing sugars react non-enzymatically with free-amino group of proteins leading to formation of advanced glycation end products (AGEs) at an accelerated rate. There is an evidence show that production and accumulation of AGEs play an important role in the initiation and development of diabetic vascular complications. In addition, in the early stage of diabetic vascular complications, endothelium disfunction is an important characteristic of it. Endothelium disfunction will cause harmful effects of vasodilation dysfunction, increase blood vessel permeability, thrombosis and so on. The occurrence of endothelial to mesenchymal transdifferentiation (EnMT) could be observed at the atherosclerotic lesions of patients with diabetes. This transdiferentiation is a hallmark of EnMT, by which endothelial cells lose their endothelial marker(von Willebrand Factor,vWF) and acquire mesenchymal cells marker(α-Smooth Muscle Actin, α-SMA)). EnMT can induce vascular fibrosis, vascular elasticity decrease and all kinds of vascular diseases. However, There is no research confirms that whether AGEs are invovled in the occurrence of EnMT. Therefore, this study will investigate whether AGEs will be involved in the ccurrence of EnMT by two experiments, providing a new research direction for the pathogenesis of diabetic vascular complications.Objective:Part I To observe the levels of AGEs, transforming growth factor-β (TGF-β1), metal matrix protease(MMP)-9 and vascular endothelial growth factor(VEGF) in the serum of patients with type 2 diabetes mellitus, and the correlation between them; Part II To observe the expression of markers in human umbilical vein endothelial cells(HUVECs) which incubated with AGEs.Methods:Part I Selecting 40 type 2 diabetic patients and 40 healthy persons, and the levels of AGEs, TGF-β1, MMP-9, VEGF in the serum of 80 subjects were detected with enzyme linked immunosorbent assay(ELISA), then the results for statistical analysis; Part Ⅱ HUVECs were respectively incubated with AGE-BSA and BSA, and then the expression of α-SMA and vWF in HUVECs were detected with immunohistochemistry and Western Blotting(WB) method after 7 days. The results for statistical analysis.Results:PartⅠ(1) The levels of AGEs, TGF-β1, MMP-9, VEGF in the serum of type 2 diabetic patients are higher than the healthy persons (P<0.01, P<0.01, P<0.05, P<0.01);(2) Pearson analysis showed that the levels of AGEs in the serum of type 2 diabetic patients were positively correlated to the levels of VEGF(r=0.642, P=0.000)、MMP-9 (r=0.946, P=0.000) and TGF-p 1 (r=0.786, P=0.000);(3) Simple linear regression analysis showed that the levels of AGEs in the serum of type 2 diabetic patients were the independent factors affecting the levels of TGF-β 1, MMP-9 and VEGF. Part II Compared with the control group of BSA, the expression of a-SMA were increased and the expression of vWF were decreased after the HUVECs were incubated by AGE-BSA for 7 days(P<0.05).Conclution:Part I The levels of some factors which are associated with the occurrence of EnMT are higher than the healthy persons, and AGEs are closely correlated with these fators, the increase of AGEs can increase the level of these factors;Part Ⅱ Exposure to AGEs can change the expressioin of surface markers of HUVECs, this suggested that the transforming of HUVECs may be involved in the pathogenesis of diabetic vascular complications.