Study on the Mechanism of Neutrophil Adhesion to Retinal Capillary Endothelial Cells under High Glucose Condition

Son, Seok Man; Lee, Young Sil; Lee, Chang Won; Yoo, Seok Dong; Kim, In Ju; Kim, Yong Ki

Abstract

BACKGROUND: Diabetic retinopathy is a leading cause of adult vision loss and blindness. Much of the retinal damage that characterizes the disease results from retinal vascular leakage and occlusion. Capillary occlusion is the result of microvascular thrombi in which erythrocytes, platelets and leukocytes each may play a major role. Thus, we investigated the pathogenesis of leukocyte stasis by exposing bovine retinal capillary endothelial cells (BRCECs) for high glucose concentration.
METHODS
We examined the adhesion of neutrophils to BRCECs incubated in media containing 5.5-30 mmol/L D-glucose for 24 hours. We also measured the expression of E-selectin on endothelial cells and the activation of NF(nuclear transcription factor)-kappaB in nuclear fractions of endothelial cells by using electrophoretic mobility shift assay.
RESULTS
We observed that 30 mmol/L D-glucose significantly increased the adhesion of neutrophils to BRCECs (12.5% vs. 3.0%, p<0.01) and migration of neutrophil across cultured BRCEC monolayers (41.0% vs. 21.0%, p<0.05) in respect to 5.5 mmol/L D-glucose. The expression of E-selectin was increased incubated with 30 mmol/L D-glucose compared with 5.5 mmol/L D-glucose (1.45 OD vs. 0.54 OD, p<0.01). Electrophoretic mobility shift assay of nuclear extracts of BRCECs exposed for 24 h to 30 mmol/L D-glucose revealed an intense NF-kappaB activation compared with cells cultured in 5.5 mmol/L D-glucose (8.72x104 countsxmm2 vs.1.88x104 countsxmm2, p<0.01).
CONCLUSION
These results suggest that high glucose concentration promote neutrophil adhesion to the BRCECs through upregulation of cell surface expression of E-selectin, possibly depending on NF-kappaB activation and may have implications for the induction of microvasculopathy of diabetic retinopathy.