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Lynn K. Gordon, Shawn A. Morales, David G. Telander, David R. Hinton, Christine Spree, Jonathan Braun; Primary RPE Express High Levels Of Epithelial Membrane Protein 2 (EMP2)-Implications For PVR Progression. Invest. Ophthalmol. Vis. Sci. 2011;52(14):6591.
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© ARVO (1962-2015); The Authors (2016-present)
The retinal pigment epithelium (RPE) plays an important role in proliferative vitreoretinopathy (PVR), an aberrant wound-healing process caused in part by RPE cell migration, membrane formation, and contractile cellular forces leading to tractional retinal detachment. Using an in vitro model of PVR, collagen gel contraction, we have previously shown that EMP2 regulates collagen gel contraction by facilitating FAK recruitment and activation in ARPE-19 cells. The purpose of this study is to determine if EMP2 is expressed in primary RPE cells and whether blockade of EMP2 could control contraction of collagen gels, an in vitro model for mechanisms involved in PVR.
Primary human RPE cells were cultured according to published methods and used in these studies. EMP2 and p-FAK expression was assessed in ARPE-19 and primary RPE cells by Western blot. Collagen gel contraction was measured using an in vitro assay. Cell viability was calculated by Trypan blue exclusion. EMP2 localization was determined by confocal microscopy using polarized primary RPE cells.
Primary RPE cells express high levels of EMP2 and p-FAK. Expression is increased 88% and 125% respectively for EMP2 and p-FAK when compared to ARPE-19 cells (P<0.05). Expression of EMP2 is largely localized to the apical cell surface in the polarized epithelium. Primary RPE cells are able to contract a collagen gel and, concordant with the high levels of EMP2, their contractile capacity is increased 55% as compared to ARPE-19 cells (P<0.05). Gel contraction by the primary RPE cells is significantly reduced following reduction of EMP2 using an anti-EMP2 diabody.
Human primary RPE cells express high levels of EMP2 and p-FAK and demonstrate a robust contractile capacity. The connection between these three factors as seen in ARPE-19 cells is preserved in primary RPE cells. Targeting EMP2 with and anti-EMP2 antibody reduces contraction and may serve as a novel therapeutic target in prevention of PVR.
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