In vivo Gene Expression Profiling of RPE/choroid Post-Intravitreal Injections of Dexamethasone and Triamcinolone at Clinically Relevant Time Points for Patient Care

PURPOSE To identify retinal pigment epithelial (RPE)/choroid genes and their relevant expression pathways affected by intravitreal injections of dexamethasone and triamcinolone acetonide in mice at clinically relevant time points for patient care. METHODS Differential gene expression of over 34,000 well-characterized mouse genes, in the RPE/choroid of 6 week old C57BL/6J mice were analyzed after intravitreal steroid injections at 1 week and 1 month post injection, using Affymetrix Mouse Genome 430 2.0 microarrays. The data were analyzed using GeneSpringGX12.5 and Ingenuity Pathway Analysis (IPA) microarray analysis software for biologically relevant changes. RESULTS Both triamcinolone and dexamethasone caused differential activation of genes involved in Circadian Rhythm Signaling pathway at both time points tested. Triamcinolone (TAA) uniquely induced significant changes in gene expression in Calcium Signaling (1 week) and Glutamate Signaling pathways (1month). In contrast, Dexamethasone (Dex) affected the GABA Receptor Signaling (1 week) and Serotonin Receptor Signaling (1month) pathways. CONCLUSIONS Understanding how intraocular steroids affect the gene expression of RPE/choroid is clinically relevant. This in vivo study has elucidated several genes and pathways that are potentially altering the circadian rhythms and several other neurotransmitter pathways in RPE/choroid cells during intravitreal steroid injections, which likely has consequences in the dysregulation of RPE function and neurodegeneration of the retina.

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Smit-McBride Z, Moisseiev E, Modjtahedi SP, Telander DG, Hjelmeland LM, Morse LS