Age Related Macular Degeneration (AMD) is a major blinding disease of the elderly in this country and, while VEGF inhibitors often stem the late, exudative stages of the disease, there is no effective therapy for the earlier, atrophic form of AMD. Oxidative damage to the retinal pigment epithelium (RPE) contributes to AMD by reducing the function of these cells and by stimulating an inflammatory cascade that leads to the pathologic hallmarks of the disease, localized atrophy of the retina and choroidal neovascularization. One source of the RPE- damaging reactive oxygen species (ROS) are the mitochondria of the RPE cells themselves. To determine whether mitochondria are an important source of ROS in the RPE in vivo, the SOD2 gene, encoding the protective enzyme MnSOD, will be deleted specifically in the RPE of mice, using a mouse line containing an allele of SOD2 flanked by loxP sites and RPE-specific expression of Cre recombinase. We plan 3 sets of experiments: (1) We will monitor the time course of retinal degeneration in real time in living mice using electrophysiology (ERG), high resolution structural analysis (SD-OCT) and behavioral analysis (Optomotry). In post mortem samples, we will examine morphological changes to the RPE, Bruch's membrane and the neural retina and to measure accumulation of lipofuscin in the RPE. We will induce the deletion of SOD2 both in neonatal and in adult mice to determine which approach better models human geographic atrophy. (2) We will increase mitochondrial oxidative stress by deletion of SOD2 in mice bearing a homozygous mutation in the gene for the transcription factor Nrl. These mice have a cone-only retina which may resemble the cone-rich human macula better than the normal mouse retina. By this means we hope to learn why the central retina is more sensitive to oxidative stress than the peripheral retina. (3) We will attempt to counteract mitochondrial oxidative stress by elevating a set of antioxidant enzymes, including heme oxygenase-1, glutathione transferases, and NAD(P)H:quinone oxidoreductase 1. These genes for these enzymes contain a common sequence component denoted """"""""ARE"""""""" for antioxidant sequence element. We will stimulate this antioxidant response in two ways-by viral delivery of a gene that stimulates the response and by oral delivery of a novel drug that activates this pathway. We hope that these approaches may lead to a therapy for the atrophic form of AMD.

Public Health Relevance

Age related macular degeneration (AMD) is the leading cause of blindness among the elderly in the United States. It is caused by degradation of the central retina, an area called the macula. There are two forms of the disease: atrophic or """"""""dry"""""""" AMD and exudative or """"""""wet"""""""" AMD. This project seeks to establish a mouse model of the pathology related to AMD and to use this model to test potential therapies for the atrophic form of the disease.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY020825-02
Application #
8233302
Study Section
Special Emphasis Panel (ZRG1-CB-G (90))
Program Officer
Shen, Grace L
Project Start
2011-03-01
Project End
2014-02-28
Budget Start
2012-03-01
Budget End
2013-02-28
Support Year
2
Fiscal Year
2012
Total Cost
$542,357
Indirect Cost
$169,574
Name
University of Florida
Department
Genetics
Type
Schools of Medicine
DUNS #
969663814
City
Gainesville
State
FL
Country
United States
Zip Code
32611
Biswal, Manas R; Han, Pingyang; Zhu, Ping et al. (2017) Timing of Antioxidant Gene Therapy: Implications for Treating Dry AMD. Invest Ophthalmol Vis Sci 58:1237-1245
Ildefonso, Cristhian J; Biswal, Manas R; Ahmed, Chulbul M et al. (2016) The NLRP3 Inflammasome and its Role in Age-Related Macular Degeneration. Adv Exp Med Biol 854:59-65
Berkowitz, Bruce A; Lewin, Alfred S; Biswal, Manas R et al. (2016) MRI of Retinal Free Radical Production With Laminar Resolution In Vivo. Invest Ophthalmol Vis Sci 57:577-85
Biswal, Manas R; Ildefonso, Cristhian J; Mao, Haoyu et al. (2016) Conditional Induction of Oxidative Stress in RPE: A Mouse Model of Progressive Retinal Degeneration. Adv Exp Med Biol 854:31-7
Ildefonso, Cristhian J; Jaime, Henrique; Biswal, Manas R et al. (2015) Gene therapy with the caspase activation and recruitment domain reduces the ocular inflammatory response. Mol Ther 23:875-884
Mitter, Sayak K; Song, Chunjuan; Qi, Xiaoping et al. (2014) Dysregulated autophagy in the RPE is associated with increased susceptibility to oxidative stress and AMD. Autophagy 10:1989-2005
Mao, Haoyu; Seo, Soo Jung; Biswal, Manas R et al. (2014) Mitochondrial oxidative stress in the retinal pigment epithelium leads to localized retinal degeneration. Invest Ophthalmol Vis Sci 55:4613-27
Wang, Rui; Paul, Valerie J; Luesch, Hendrik (2013) Seaweed extracts and unsaturated fatty acid constituents from the green alga Ulva lactuca as activators of the cytoprotective Nrf2-ARE pathway. Free Radic Biol Med 57:141-53
Wang, Rui; Mason, Daniel E; Choe, Keith P et al. (2013) In vitro and in vivo characterization of a tunable dual-reactivity probe of the Nrf2-ARE pathway. ACS Chem Biol 8:1764-74
Seo, Soo-jung; Krebs, Mark P; Mao, Haoyu et al. (2012) Pathological consequences of long-term mitochondrial oxidative stress in the mouse retinal pigment epithelium. Exp Eye Res 101:60-71