Microarray Pathway Analysis of C57BL/6J Mouse Retinal Gene Expression Following Intravitreal Injection of Triamcinolone and Vascular Endothelial Growth Factor

Abstract

Purpose: : To identify gene expression pathways affected by intravitreal injections of triamcinolone acetonide (TA) or vascular endothelial growth factor (VEGF) in the C57BL/6J mouse eye.

Methods: : All research was conducted in compliance with the ARVO statement for the use of animals in ophthalmic and vision research. Intravitreal injections were performed transconjunctivally in anesthetized C57BL/6J mice with Hamilton syringes and 33g needles delivering 2 ul of solution according to institutional protocol. In group 1 (n=3) animals received intravitreal TA (0.08mg), in group 2 (n=3) VEGF (1mg/cc), in group 3 (n=3) balanced salt solution (BSS), and in group 4 (n=3) a combination of TA and VEGF. Ninety-six hours after the injections, mice from each group were sacrificed by pentobarbital sodium overdose (120mg/kg, IP) and the eyes were harvested for retinal dissection and total RNA isolation. Microarray analysis was performed using Affymetrix MOE-430A GeneChip arrays. Pathway analysis of the microarray data was performed using GeneSpring GX and IPA software.

Results: : When TA treatment was compared to the controls (group 1 vs. group 3), several signaling pathways such as nuclear factor-kappa B (NF-kB), Actin cytoskeleton, Antigen (Ag) presentation and Fibrosis induction pathways were activated. When VEGF treatment was compared to the controls (group 2 vs. 3) Actin cytoskeleton, Fibrosis, Ag presentation and calcium (Ca++) signaling pathways were activated. When TA and VEGF combination treatment was compared to the controls (group 4 vs. 3) Actin cytoskeleton, Ca++ and Interleukin-4 (IL-4) signaling pathways were affected.

Conclusions: : Microarray pathway analysis identifies effects of TA and VEGF on retinal gene expression in the C57BL/6J mouse eye. In VEGF treated animals we observed up-regulation of several pro-angiogenic factors (i.e angiopoietin-like protein 6 [Angptl6]), and down-regulation of anti-angiogenic factors (i.e. pigment epithelium-derived factor [PEDF]). With TA treatment, we observed down-regulation of proangiogenic factors (i.e. Kdr [VEGF receptor] and VEGF B). Our preliminary data suggests activation of angiogenesis pathways with VEGF, and down-regulation with TA.

Keywords: gene microarray • gene/expression • drug toxicity/drug effects