Activated Status and Altered Functions of Neutrophils in Poorly Controlled Diabetes

Abstract

Objectives. This study aimed to investigate the association of hyperglycemia and AGE on the phenotypes and biological functions of neutrophils to understand their roles in diabetes-related atherosclerosis. Methodology. Healthy subjects (HS) (n=5) and type 2 diabetic patients grouped according to glycemic control [good control, HbA1c 7% or less, n=6 (well controlled diabetic, WCD); poor control, HbA1c more than 9%, n=6 (poorly controlled diabetic, PCD)] were included in the study. Neutrophils were isolated from peripheral venous blood samples. To determine in vitro effects of high glucose and AGE, neutrophils derived from HS were exposed to 5 mM glucose, 25 mM glucose, 100 μg/mL BSA and AGE-BSA. We determined basal and PMA-stimulated production of ROS, expression of CD11b and CD66b, release of MPO, cell migration to IL-8 and adhesion to an endothelial cell layer. Results. In diabetic subjects, cells from WCD produced significantly higher basal and PMA-stimulated ROS ( p =0.014), while cells from PCD showed significantly increased expression of CD11b, CD66b and MPO production (p=0.021, 0.034, 0.05, respectively). The release of MPO was significantly increased after PMA stimulation in cells incubated in AGE-BSA, compared to those incubated in unmodified BSA. We observed significantly enhanced migration towards IL-8 and adherence to endothelial cells in neutrophils exposed to high glucose. Conclusions. Our findings indicate the activated status of neutrophils from diabetic patients. Neutrophils from healthy subjects exposed to conditions simulating hyperglycemia showed increased adhesive capacity. We made the novel finding of enhanced neutrophil migration toward IL-8 and adherence to endothelial cells upon exposure to high glucose conditions. These altered neutrophil functions may lead to the development and progression of atherosclerosis in diabetes.