Abstract
Abstract: :
Purpose: In proliferative vitreoretinopathy, cells enter and proliferate in the vitreous, a process that can ultimately lead to retinal detachment. Retinal pigment epithelial (RPE) cells, which appear to play an important role, undergo morphological changes and become more fibroblast-like. Similar morphological changes are observed if RPE cells in culture are treated with vitreous or collagen I. We have begun to investigate changes in gene expression in cultured RPE cells treated with vitreous or collagen I. Methods: Human Atlas Cancer cDNA arrays (Clontech) were used to detect vitreous- or collagen-induced changes in RNA expression in cultures of low passage human RPE cells. RPE cells and vitreous were from multiple donors. The expression of mRNA for genes of interest was further quantified by real-time PCR. Immunoblotting was used to examine protein levels. Immunofluorescence and confocal microscopy were used to examine the location of the proteins. Results: The steady state concentration of microsomal prostaglandin E synthase (mPGES) mRNA and protein was upregulated by vitreous in RPE cells and was still elevated after 48 hours of treatment. Since the substrate for mPGES is made by cyclooxygenases, we examined the mRNA levels for cyclooxygenase-2 (Cox-2), which can be induced by exposure of cells to a variety of mediators. Cox-2 mRNA was upregulated by vitreous, the mRNA levels were similar to controls by 24hr. Treatment of cells with collagen I caused a change in RPE cell morphology which appeared similar to that caused by vitreous, but caused little or no induction of mPGES mRNA or Cox-2 mRNA at the time points examined (6, 12, 24 and 48 hours of treatment). Conclusion: Vitreous treatment of low-passage human RPE cells induces expression of mPGES mRNA and protein. There is a transient induction of cox-2 mRNA. Although collagen induces a morphological change in these cells which looks similar to that induced by vitreous, it does not appear to have significant effects on the steady state levels of mRNA for mPGES or cox-2 at the time points examined.
Keywords: 567 retinal pigment epithelium • 524 proliferative vitreoretinopathy • 629 vitreous