Abstract
Purpose: :
Cellular changes have been identified in almost every cell type in the retina in response to retinal detachment. Photoreceptors undergo degeneration and often apoptosis. Retinal neurons exhibit rapid neurite outgrowth and synaptic changes. Mueller cell hypertrophy and proliferation often lead to the creation of glial scars. Macrophages invade the subretinal space and microglia become activated, undergo proliferation, and migrate to the outer retina, presumably, in order to clear cellular debris from degenerating photoreceptors. The purpose of this project was to use an experimental model of retinal detachment in mice in conjunction with microarray analysis to study the differential gene expression patterns in the detached retina.
Methods: :
Retinal detachments were created in the right eyes of four C57J/B6 mice. Left eyes were used as controls. Eyes were enucleated at 7 days in ice cold HBSS and total RNA was extracted with Ambion’s mirVANA mRNA isolation kit according to manufacture’s instructions. The extracted mRNA integrity was analyzed with Agilent’s bioanalyzer 2000. Microarray analysis was performed using Agilent’s 4x44K mouse whole genome array kit.
Results: :
The genes that were upregulated by 200% or more can be associated with four broad categories: neural, glial, inflammation, and hematopoesis. Several of these genes coincide with changes already determined by immunohistochemistry, including the upregulation of GFAP, vimentin, and CD44. Of the genes upregulated by at least 200% in all four data sets over 75% are genes associated with the inflammatory response. Examples include: B2M, CCL2 (MCP-1), ICAM-1, and TLR2.
Conclusions: :
Microarray analysis reveals genetic changes occurring in all major classes of retinal cell types in response to retinal detachment. Somewhat surprising is the prominent upregulation of genes involved in the inflammatory response. The results suggest that direction for future research should include determining how various signaling cascades are coordinated to produce the cellular responses initiated by detachment. Manipulation of these signaling cascades could provide therapy for the prevention of photoreceptor death, glial scar formation, proliferative vitreoretinopathy, and neuronal remodeling ultimately leading to improved visual recovery after reattachment of the retina.
Keywords: retinal detachment • gene microarray • inflammation