Abstract
Purpose::
Chemical cautery-induced corneal neovascularization is a well-characterized experimental model of ocular pathology. A chemical burn of the central corneal epithelium leads to early infiltration of polymorphonuclear neutrophils, followed by macrophages within the corneal stroma, rapid and dense growth of new blood vessels centripetally from the limbus, and late maturation and thinning of new vessels. This study used proteomic analysis to look at quantitative changes in protein expression within the cornea and the iris-ciliary body throughout the time course of this model.
Methods::
Corneal neovascularization was induced by chemical cautery (Ag/K nitrate) in both eyes of female Sprague-Dawley rats. The cornea and iris-ciliary body were harvested from eyes on days 1, 3, 5, and 7 after cautery. The same tissues were collected from naïve rats as comparative controls. Proteins were extracted from all tissues and analyzed by a Luminex assay quantifying a panel of sixty proteins (rodent multi-analyte panel). The temporal patterns of increases in protein levels relative to baseline were correlated with the known and previously reported progressive phases of corneal neovascular growth and the cell types that have been shown to be involved at each phase as identified by histology and immunohistochemistry.
Results::
Quantitative analysis of proteins in the cornea or in the iris-ciliary body post-corneal cautery shows different magnitudes of fold increase and distinct temporal patterns in which peak increases can be correlated with pre-angiogenic, angiogenic, or post-angiogenic stages of corneal neovascularization. The largest fold increases in protein levels occur in inflammatory cell-associated proteins that peak in the pre-angiogenic (day 1 during neutrophil infiltration) or angiogenic stages (days 3 and 5 during the presence of macrophages). Various angiogenic proteins and growth factors also peak during these early stages. In contrast, some interleukins and blood-associated proteins show greater increases later in the post-angiogenic stage when vascular perfusion might be increased in the new corneal blood vessels.
Conclusions::
This is the first report of broad-based proteomic analysis being used to investigate protein expression in a model of corneal neovascularization. This approach may be useful in determining the effects of pharmacologic therapies on a specific tissue proteome, and it may be used as a diagnostic tool to identify molecular markers associated with ocular angiogenic disease.
Keywords: cytokines/chemokines • inflammation • proteomics