Localization of Human Copper Transporter 1 in the Eye and its Role in Eales Disease.

PURPOSE: Copper (Cu) is an essential trace element; however excess is toxic due to the pro-oxidant activity. Increased intracellular Cu levels in vitreous and monocyte were reported in Eales disease (ED) previously. Copper transporter1 (CTR1) maintains copper homeostasis and hence, we studied the presence of CTR1 in ocular tissues and its role in ED. METHODS: Real-time PCR, ELISA and Western blot experiments were performed in donor eyeballs tissues and PBMCs isolated from controls and ED. Immunostaining were performed for CTR1 from donor eyeballs and one ED case. RESULTS: CTR1 protein was expressed in all ocular tissues. PBMCs showed a three-fold increase in CTR1 protein in ED when compared with controls. Retinal sections from ED patients also revealed increased CTR1 protein expression in retinal tissues, compared with control. CONCLUSIONS: CTR1 was significantly increased in ED when compared with controls, indicating its considerable role in the ED pathology.

Tolerance of ARPE 19 cells to organophosphorus pesticide chlorpyrifos is limited to concentration and time of exposure.

Age related macular degeneration is a blinding disease common in elder adults. The prevalence of age related macular degeneration has been found to be 1.8% in the Indian population. Organophosphates are widely used insecticides with well documented neurological effects, and the persistent nature of these compounds in the body results in long term health effects. Farmers exposed to organophosphorus pesticides in USA had an earlier onset of age related macular degeneration when compared to unexposed controls. A recent study found significant levels of an organophosphate, termed chlorpyrifos, in the blood samples of Indian farmers. Therefore, in understanding the link between age related macular degeneration and chlorpyrifos, the need for investigation is important. Our data show that ARPE-19 (retinal pigment epithelial cells) exhibit a cytoprotective response to chlorpyrifos as measured by viability, mitochondrial membrane potential, superoxide dismutase activity, and increased levels of glutathione peroxidase and reduced glutathione, after 24 h exposure to chlorpyrifos. However, this cytoprotective response was absent in ARPE-19 cells exposed to the same range of concentrations of chlorpyrifos for 48 h. These results have physiological significance, since HPLC analysis showed that effects of chlorpyrifos were mediated through its entry into ARPE-19 cells. HPLC analysis also showed that chlorpyrifos remained stable, as we recovered up to 80% of the chlorpyrifos added to 6 different ocular tissues.

Homocysteine levels in the vitreous of proliferative diabetic retinopathy and rhegmatogenous retinal detachment: its modulating role on lysyl oxidase.

PURPOSE: Homocysteine (Hcys), a well-known inducer of vascular endothelial cell damage has been associated with extracellular matrix changes. Lysyl oxidase (LOX) is a copper-dependent amine oxidase that initiates the covalent cross-linking of collagen and elastin in the extracellular matrix (ECM). LOX contributes to the structural integrity of the ECM, and low LOX activity could promote ECM disorganization. Hydroxyproline levels are used to predict collagen turnover status, and most of the endogenous hydroxyproline present in biological fluids is derived from the degradation of various forms of collagen. As Hcys is known to regulate ECM turnover and also inhibit LOX activity, the purpose of this study was to estimate the vitreous levels of Hcys in eyes with proliferative diabetic retinopathy (PDR) and rhegmatogenous retinal detachment (RRD) and to correlate the effect of Hcys, if any on LOX activity. METHODS: Undiluted human vitreous specimens obtained during vitreoretinal surgeries for PDR (n = 18) and RRD (n = 17) were used. Vitreous specimens from donor eyeballs were used as control (n = 19). Hcys was estimated by HPLC using a fluorescent detector. Hydroxyproline was estimated spectrophotometrically. RESULTS: The total vitreous Hcys level was found to be increased significantly in PDR (P = 0.011) and in RRD (P = 0.001) compared with that in control samples. Hydroxyproline was significantly increased in PDR (P = 0.049) and RRD (P = 0.007) compared with the level in control samples. There was a significant negative correlation between the Hcys level and the specific activity of LOX in PDR (P = 0.040) and in RRD (P = 0.029) CONCLUSIONS: This report shows that increased vitreous Hcys in PDR and RRD is associated with a significant decrease in LOX-specific activity along with an increase in collagen turnover.