Abstract
Purpose:
To assess the relationship between endothelial progenitor cells, inflammation, and retinopathy phenotype in type 2 diabetes.
Methods:
26 patients with type 2 diabetes and 30 healthy controls were included. Patients were classified according to retinopathy grade. Mononuclear cells were isolated from peripheral blood, and endothelial progenitor cells (EPCs) identified by flow cytometry. Monocyte profiles were also assessed.
Results:
The proportion of CD34+ EPCs co-expressing VEGFR2 was significantly greater in diabetes (5.77%±2.15) compared to healthy controls (2.14±2.00) (p=0.001). In diabetes, low levels of circulating CD34+ EPCs were also associated with monocytes co-expressing the monocyte activation marker CD163, and pro-angiogenic VEGFR2 (r=-0.53, p=0.04). On examination of monocyte subtypes- (1) pro-inflammatory monocytes (CD14+ CD16++) had a higher expression of CD163 (p=0.03) in patients with a body mass index of >30; (2) classical monocytes (CD14+ CD16-) had a higher expression of VEGFR2 and CD163 (p=0.03) in macular oedema; and (3) Intermediate monocytes (CD14+ CD16+) had a higher expression of VEGFR2 (p=0.05) in macular ischaemia.
Conclusions:
Evaluation of cellular participants of vascular repair and chronic inflammation may offer an explanation as to why different phenotypes of diabetic retinopathy manifest, provide new insights into mechanisms of visual loss, and provide potential avenues for novel therapeutic approaches in this disease.
Keywords: 499 diabetic retinopathy •
557 inflammation •
529 flow cytometry