12-Lipoxygenase: A New Target for Therapeutic Intervention in Diabetic (Ischemic) Retinopathy
Abstract Number: 24-LB
Authors: RENE A. MUSSELL, MOHAMED ELADL, JULIAN NUSSBAUM, KENNETH V. HONN, KRISHNA R. MADDIPATI, VIJAY P. SARTHY, AMANY TAWFIK, MOHAMED A. AL-SHABRAWEY
Institutions: Augusta, GA, Detroit, MI, Chicago, IL
Results: Diabetic retinopathy (DR) is a vision threatening complication of diabetes. Vascular injury in diabetic retina involves leukostasis, and vascular leakage and growth. Disruption of the normal balance between the pro-and antiangiogenic factors vascular endothelial growth factor (VEGF) and pigment epithelium derived factor (PEDF) has been reported to be critical in DR. Arachidonic acid is metabolized by 12-lipoxygenase (12-LO) to 12- hydroxyeicosatetraenoic acid (12-HETE) which has been reported to beinvolved in angiogenesis, and promotes mitogenic and migration properties of microvascular endothelial cells. 12-HETE has also been shown to induce leukostasis. The goal of this study is to investigate the changes in 12-LO expression and activity and to correlate these changes with VEGF and PEDF balance and the vascular injury associated with DR.
The experiments have been performed on vitreous from diabetic and non-diabetic patients and retinas from eye donors, mouse model of diabetes and oxygen-induced retinopathy (OIR) treated with or without 12-LO inhibitor, baicalein (10mg/kg). Western blotting and ELISA were used to evaluate the changes in 12-LO, PEDF, ICAM-1 and VEGF expression. LC/MS was used to assess the activity of 12-LO. Vascular density determination on flat mount retinas from OIR labeled with Isolectin B4 was used to evaluate the effect of 12-LO inhibition on retinal neovascularization. We also tested the effect of 12-HETE (0.5-1mM) on Müller cell expression of VEGF and PEDF. Diabetes increased retinal 12-LO expression in human and mice; this was associated with a dramatic increase in the retinal level of ICAM-1. Both expression and activity of 12-LO were significantly increased in OIR and baicalein significantly decreased neovascularization, and restored the balance in VEGF and PEDF expression. 12-HETE significantly increased VEGF and decreased PEDF production by Müller cells. Analysis of patient vitreous confirmed the clear inverse relationship between 12-LO activity and PEDF expression. This indicates that 12-LO activity is key to the development of DR by disrupting the balance between PEDF and VEGF. Inhibition of 12-LO could be a new target to treat DR.