Increased levels of alphaB-crystallin in vitreous fluid of patients with proliferative diabetic retinopathy and correlation with vascular endothelial growth factor

Background AlphaB-crystallin has been shown to have angiogenic properties. The purpose of this study was to determine the levels of alphaB-crystallin in the vitreous fluid of patients with proliferative diabetic retinopathy and to confirm the association between the expression level of alphaB-crystallin and vascular endothelial growth factor. Methods Vitreous samples were collected before vitrectomy from 46 eyes of 46 consecutive patients with proliferative diabetic retinopathy, and 19 patients without diabetes mellitus had vitrectomy for idiopathic macular hole. The concentrations of alphaB-crystallin and vascular endothelial growth factor were measured via enzyme-linked immunosorbent assay. Results The vitreous level (mean ± SD) of alphaB-crystallin was significantly higher in patients with proliferative diabetic retinopathy (317.3 ± 151.7 ng/mL) than in control patients (idiopathic macular hole, 8.3 ± 6.1 ng/mL) (P < 0.0001). The vitreous concentration of vascular endothelial growth factor was also significantly higher in patients with proliferative diabetic retinopathy (860.1 ± 566.4 pg/mL) than in control patients (9 pg/mL) (P < 0.0001). Meanwhile, both the expression levels of alphaB-crystallin and vascular endothelial growth factor were significantly higher in eyes with active proliferative diabetic retinopathy than in those with inactive proliferative diabetic retinopathy. Also, the vitreous concentration of alphaB-crystallin correlated significantly with that of vascular endothelial growth factor in vitreous fluid of proliferative diabetic retinopathy ([correlation coefficient], R = 0.78, P < 0.001). Conclusions These results suggest a significant increase of alphaB-crystallin in the vitreous fluid of patients with proliferative diabetic retinopathy and present a crucial association between alphaB-crystallin and vascular endothelial growth factor with angiogenic activity in proliferative diabetic retinopathy.