Unknown,Transcriptomics,Genomics,Proteomics

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Dry age-related macular degeneration like pathology in aged 5XFAD mice: Ultrastructure and microarray analysis

ABSTRACT: Age-related macular degeneration (AMD) is a leading cause of blindness in the elderly. There are two types of AMD: dry AMD and wet AMD. While laser-induced choroidal neovascularization has been used extensively in the studies of wet AMD by presenting the main features of human wet AMD, there was no established mouse model which fully recapitulates the cardinal features of human dry AMD. In this regard, lack of appropriate mouse model for dry AMD hampered the translational research on the pathogenesis and development of therapeutic agents. We recently suggested that 5XFAD mice could be a mouse model of dry AMD with regard to the amyloid beta (AÎ²) related pathology. In this study, using transmission electron microscope, we analyzed ultrastructure of retinal pigment epithelium (RPE) of 5XFAD mice. Of importance, aged 5XFAD mice had ultrastructural changes of RPE and Bruchâs membrane compatible with cardinal features of dry AMD, including loss of apical microvilli and basal infolding of RPE, increased thickness of Bruchâs membrane, basal laminar and linear deposits, and accumulation of lipofuscin granules and undigested photoreceptor outer segment-laiden phagosomes. Using a threshold of 1.2 fold difference, we found â564â differentially expressed genes of which â190â were up-regulated and â374â were down-regulated in the RPE complex of aged 5XFAD mice. These altered genes were implicated in the pathogenesis of AMD including inflammation and immune response-related genes and retinol metabolism-related genes. Taken together, we suggest that aged 5XFAD mice can be used for dry AMD mouse model. All 5XFAD mice used were heterozygotes with respect to the transgene, and non-transgenic wild-type littermate (WT) mice served as controls.

ORGANISM(S): Mus musculus

SUBMITTER: Sung Wook Park

PROVIDER: E-GEOD-85408 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Background: Different sources of retinal pigment epithelial cells (RPE) were transplanted to treat Age-related Macular Degeneration. But the mechanisms of therapeutic effect are unclear till now, and GMP level fetal RPE (fRPE) need further evaluation for treatment. Methods: Modified GMP fRPE primary culture system was founded. These RPE were tested on Mer-/- mice and sodium iodate induced retinopathy primate model for safety and feasibility. Five dry-AMD patients and one Stargardt’s Disease patient were enrolled, and received sub retinal transplantation of hfRPE with three dosage cohorts(1×105，2×105，5×105). ETDRS, optic coherent tomographic imaging (OCT), color fundus (CF), fluorescent angiography (FFA), autofluorescence, microperimetry examination were conducted before surgery, and during follow-up period. The studies are registered with ClinicalTrials.gov, numbers NCT02868424. Findings: GMP level fRPE from modified primary culture system has good proliferative capacity and full functions of RPE in vitro. Human fetal RPE can survive long period in sub-retinal space in mice and monkey models of RPE degeneration, and showed therapeutic effect on Mer-/- mice. During our nine-months follow-up of six clinical cases, no endophthalmitis, no vitreous hemorrhage, no proliferative vitreoretinopathy was observed, and epiretinal memrbrane was the only complication. Among the patients, four of them achieved increase in ETDRS visual acuity (VA), of which the greatest improvement was 18 letters, and one kept steady while the other had 9 letters decreased VA. Color fundus photos and OCT demonstrated the existence of the fRPE cells, and improved retinal sensitivity as well as the changes observed in auto fluorescence also can tell the situation of grafted cells to some extent. Interpretation: GMP level fRPE from modified culture system exhibited satisfactory results on in vitro and preclinical experiments. Preliminary clinical trial proved safety of the fRPE subretinal transplantation, and substantiated it a promising therapy for dry AMD including the converted from exudative AMD.

Project description:Background Age-related macular degeneration (AMD) is the leading cause of irreversible blindness in the elderly population worldwide. Recent studies have demonstrated strong genetic associations between AMD and single nucleotide polymorphisms (SNPs) within genes such as CFH and HTRA1. However, we have identified monozygotic twins discordant for AMD phenotypes (one with disease, the other without disease), suggesting that an epigenetic mechanism may also contribute to the pathogenesis of AMD. Methods We identified two twin pairs with phenotypic discordance of AMD. We obtained genomic DNA from their peripheral blood mononuclear cells (PBMCs) and subjected them to DNA methylation-chip analysis (MeDIP-chip) that profiled genome-wide DNA methylation patterns on promoters of all genes and microRNAs. We next utilized the Methyl-Profiler DNA methylation assays to detect the methylation status of selected promoters. Flow cytometry and quantitative real-time PCR were used to detect the expression of the selected gene in peripheral blood cells, as well as in retinal and choroidal tissues of AMD patients and non-AMD controls. Results Our MeDIP-chip analysis identified 256 genes with hypo-methylated promoters only in the twins with AMD and 744 genes with hyper-methylated promoters only in the twins with AMD. Importantly, the promoter region of IL17RC was associated with hypo-methylated CpG sites only in the twins with AMD but not in the twins without AMD. We also found the association of the hypo-methylated IL17RC promoter with AMD in 7 pairs of siblings with discordant AMD pathology (P=0.003), as well as an independent patient cohort (95 neovascular wet and 107 geographic atrophy dry AMD patients as well as 96 non-AMD controls (95% CI, 0.01-0.10, P=9.8x10-8 for wet AMD vs. control; 95% CI, 0.05-0.32, P=2.2x10-5 for dry AMD vs. control)). Interestingly, we did not find an association between the levels of methylation on the IL17RC promoter with the previously identified genetic risk alleles in CFH, HTRA1, and ARMS2. We demonstrated an elevated expression of the IL-17RC protein in CD14+ monocytes in the peripheral blood of AMD patients as compared to non-AMD controls. These IL-17RC+ monocytes have elevated expression of CXCR1, CXCR2, and CXCR4. In addition, IL17RC was expressed only in the retinal and choroidal tissues from AMD patients but not from age-matched controls. Conclusions We show an association of the hypo-methylated IL17RC promoter with AMD, which resulted in the elevated expression of IL-17RC in peripheral blood cells as well as the retinal and choroidal tissues of AMD patients. Our study suggests that the hypo-methylated IL17RC promoter and elevated expression of IL-17RC can potentially serve as biomarkers for the diagnosis of AMD, while IL-17RC can be a new therapeutic target for AMD. In addition, our results strongly suggest an epigenetic control mechanism of AMD pathogenesis. The Affymetrix MOE430 2.0 GeneChip was used to detect gene expression patterns within the whole eye of C57B/6 normal mice.

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Dry age-related macular degeneration like pathology in aged 5XFAD mice: Ultrastructure and microarray analysis

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