Enhanced expression of intercellular adhesion molecule–1 of human retinal endothelial cells after insulin exposure

Abstract

Abstract: : Purpose: Acute intensive insulin therapy often causes a transient worsening of diabetic retinopathy. Recent studies suggested that leukocyte adhesion to the retinal vascular endothelial cells plays a key role in the pathogenesis of diabetic retinopathy. In the present study, we evaluated the effect of insulin on surface expression of endothelial adhesion molecules on human retinal endothelial cells (HRECs). Methods: HRECs were cultured for 48 h in insulin–rich medium. Control cells were cultured in CS–C medium. Cells were incubated with anti–adhesion molecules (ICAM–1, P–selectin, and E–selectin) antibody for 60 min, followed by incubation with horseradish peroxidase–conjugated goat anti–mouse IgG for 60 min. Surface expression of endothelial adhesion molecules were quantitatively studied with the use of an enzyme immunoassay. Results: Surface expression of ICAM–1 significantly increased when HRECs were exposed to 100µU/ml insulin for 48 h (0.242 ± 0.008) as compared with the control cells (0.198 ± 0.012, P<0.05). However, endothelial expression of P–selectin and E–selectin was not affected by insulin exposure. Conclusions: These results suggested that insulin enhances the expression of ICAM–1 on HRECs. Enhanced expression of ICAM–1 may participate in the pathogenesis of transient worsening of diabetic retinopathy after intensive insulin therapy.

Keywords: cell adhesions/cell junctions