Abstract
Abstract: :
Purpose: Combination of both environmental and genetic factors may be involved in the pathogenesis of AMD. For example, nonlethal oxidative injury to Retinal Pigment Epithelia (RPE) may contribute to histologic changes seen in early AMD. However, direct examination of RPE cells from the AMD patients is difficult. A number of studies have demonstrated that peripheral tissues could be used to detect altered patterns of gene expression in the central nervous system of Alzheimer’s patients. The purpose of this study was to determine whether the expression profiles of the genes involved in wound repair, cell injury and matrix turnover are altered in fibroblasts from AMD and age–matching control patients before and after treatment with nonlethal oxidative stimuli. Methods: Dermal biopsies from 11 patients with early and late AMD and age–matched controls were used to establish primary fibroblast cultures, which were then treated with nonlethaly doses of oxidative stimuli menadione. Gene expression patterns were quantitatively and qualitatively examined using Human Genome U95A GeneChips (Affymetrix) and verified by real–time PCR analysis. Results: No significant differences in gene expression patterns were observed between the control, early and late AMD patient’s groups before treatment. However, after nonlethal treatment 755 genes were upregulated at least two fold in one of the groups. A number of functional gene groups were dysregulated in disease affected patients including cell cycle, apoptosis, adhesion, protection from injury and transcriptional regulation in response to injury. 22 functionally related genes potentially related to the development and progression of the disease demonstrated higher level of dysregulation in patients with late AMD compare to the control and early AMD. A number of genes selected from this group for the validation (HO–1, CLG, MNSOD and hCOX2) demonstrated high level of correlation between the expression microarray data and real time RT–PCR data (R2= 0.77). Conclusion: Our data demonstrated that dysregulation of multiple genes with redundant functions potentially related to the development of the disease present in fibroblasts from patients with late AMD. However, these gene expressional differences were evident only after the application of nonlethal oxidative treatment highlighting the importance of environmental factors in pathogenesis of AMD.
Keywords: age–related macular degeneration • oxidation/oxidative or free radical damage • gene microarray