Low glucose under hypoxic conditions induces unfolded protein response and produces reactive oxygen species in lens epithelial cells

Aging is enhanced by hypoxia and oxidative stress. As the lens is located in the hypoglycemic environment under hypoxia, aging lens with diabetes might aggravate these stresses. This study was designed to examine whether low glucose under hypoxic conditions induces the unfolded protein response (UPR), and also if the UPR then generates the reactive oxygen species (ROS) in lens epithelial cells (LECs). The UPR was activated within 1 h by culturing the human LECs (HLECs) and rat LECs in <1.5 mM glucose under hypoxic conditions. These conditions also induced the Nrf2-dependent antioxidant-protective UPR, production of ROS, and apoptosis. The rat LECs located in the anterior center region were the least susceptible to the UPR, whereas the proliferating LECs in the germinative zone were the most susceptible. Because the cortical lens fiber cells are differentiated from the LECs after the onset of diabetes, we suggest that these newly formed cortical fibers have lower levels of Nrf2, and are then oxidized resulting in cortical cataracts. Thus, low glucose and oxygen conditions induce the UPR, generation of ROS, and expressed the Nrf2 and Nrf2-dependent antioxidant enzymes at normal levels. But these cells eventually lose reduced glutathione (GSH) and induce apoptosis. The results indicate a new link between hypoglycemia under hypoxia and impairment of HLEC functions

Cigarette Smoke-Related Hydroquinone Dysregulates MCP-1, VEGF and PEDF Expression in Retinal Pigment Epithelium in Vitro and in Vivo

Age-related macular degeneration (AMD) is the leading cause of legal blindness in the elderly population. Debris (termed drusen) below the retinal pigment epithelium (RPE) have been recognized as a risk factor for dry AMD and its progression to wet AMD, which is characterized by choroidal neovascularization (CNV). The underlying mechanism of how drusen might elicit CNV remains undefined. Cigarette smoking, oxidative damage to the RPE and inflammation are postulated to be involved in the pathophysiology of the disease. To better understand the cellular mechanism(s) linking oxidative stress and inflammation to AMD, we examined the expression of pro-inflammatory monocyte chemoattractant protein-1 (MCP-1), pro-angiogenic vascular endothelial growth factor (VEGF) and anti-angiogenic pigment epithelial derived factor (PEDF) in RPE from smoker patients with AMD. We also evaluated the effects of hydroquinone (HQ), a major pro-oxidant in cigarette smoke on MCP-1, VEGF and PEDF expression in cultured ARPE-19 cells and RPE/choroids from C57BL/6 mice.MCP-1, VEGF and PEDF expression was examined by real-time PCR, Western blot, and ELISA. Low levels of MCP-1 protein were detected in RPE from AMD smoker patients relative to controls. Both MCP-1 mRNA and protein were downregulated in ARPE-19 cells and RPE/choroids from C57BL/6 mice after 5 days and 3 weeks of exposure to HQ-induced oxidative injury. VEGF protein expression was increased and PEDF protein expression was decreased in RPE from smoker patients with AMD versus controls resulting in increased VEGF/PEDF ratio. Treatment with HQ for 5 days and 3 weeks increased the VEGF/PEDF ratio in vitro and in vivo.We propose that impaired RPE-derived MCP-1-mediated scavenging macrophages recruitment and phagocytosis might lead to incomplete clearance of proinflammatory debris and infiltration of proangiogenic macrophages which along with increased VEGF/PEDF ratio favoring angiogenesis might promote drusen accumulation and progression to CNV in smoker patients with dry AMD

Clinical utilization of anti-vascular endothelial growth-factor agents and patient monitoring in retinal vein occlusion and diabetic macular edema

Szil&aacute;rd Kiss,1 Ying Liu,2 Joseph Brown,3 Nancy M Holekamp,4,5 Arghavan Almony,6 Joanna Campbell,2 Jonathan W Kowalski2 1Weill Cornell Medical College, New York, NY; 2Allergan, Inc., Irvine, CA; 3IMS Health, Woodland Hills, CA; 4Pepose Vision Institute, Chesterfield, MO; 5Washington University School of Medicine, St Louis, MO; 6Carolina Eye Associates, Southern Pines, NC, USA Purpose: To examine the utilization of bevacizumab and ranibizumab and disease monitoring in patients with branch or central retinal vein occlusion (BRVO/CRVO) or diabetic macular edema (DME) in clinical practice.Patients and methods: This retrospective claims analysis included newly diagnosed patients with one or more bevacizumab or ranibizumab injections. Bevacizumab or ranibizumab utilization was assessed by year of first injection:&nbsp;2008&ndash;2010&nbsp;cohorts (12-month follow-up), January to June&nbsp;2011&nbsp;cohort (6-month follow-up). The main outcome measures were mean annual numbers of injections, ophthalmologist visits and optical coherence tomography examinations, and proportion of patients with additional laser or intravitreal triamcinolone (IVTA) use.Results: A total of&nbsp;885&nbsp;BRVO,&nbsp;611&nbsp;CRVO, and&nbsp;2,733&nbsp;DME patients treated with bevacizumab were included, with too few ranibizumab-treated patients for meaningful analysis. Across the&nbsp;2008,&nbsp;2009, and&nbsp;2010&nbsp;cohorts, mean annual numbers of bevacizumab injections increased, but remained low (BRVO&nbsp;2.5,&nbsp;3.1,&nbsp;3.3; CRVO&nbsp;3.1,&nbsp;3.1,&nbsp;3.5; and DME&nbsp;2.2,&nbsp;2.5,&nbsp;3.6, respectively); mean ophthalmologist visits ranged between&nbsp;4.4&nbsp;and&nbsp;6.5, and mean optical coherence tomography examinations ranged between&nbsp;3.1&nbsp;and&nbsp;3.9&nbsp;across all conditions. A total of&nbsp;42.0% of BRVO,&nbsp;16.5% of CRVO, and&nbsp;57.7% of DME patients received additional laser or IVTA therapy. The number of bevacizumab injections was positively associated with laser use in BRVO (3.3&nbsp;versus&nbsp;2.9, P&lt;0.03), and with laser or IVTA use in DME (laser,&nbsp;3.3&nbsp;versus&nbsp;2.7, P&lt;0.03; IVTA,&nbsp;3.3&nbsp;versus&nbsp;3.0, P&lt;0.05).Conclusion: During the study period (2008&ndash;2011), bevacizumab was the main anti-VEGF therapy used in clinical practice for BRVO, CRVO, and DME. Patients treated with bevacizumab were monitored less frequently and received fewer injections than patients in major clinical trials of ranibizumab. Keywords: anti-vascular endothelial growth factor, bevacizumab, ranibizumab, diabetic macular edema, retinal vein occlusion, intravitrea