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Vijay P. Sarthy, Alex Park, V. Joseph Dudley, Richard J. Johnson; Complement Regulatory Protein Expression by Retinal Müller Cells. Invest. Ophthalmol. Vis. Sci. 2012;53(14):1646.
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© ARVO (1962-2015); The Authors (2016-present)
The complement system is important for immunosurveillance, and recent studies indicate that uncontrolled activation of the complement cascade contributes to the development and progression of AMD. Previous studies have characterized expression and modulation of complement regulatory proteins in retinal pigment epithelial cells (RPE). The goal of the present study was to identify complementary regulatory proteins expressed by Müller cells and to examine whether oxidative stress affects their expression.
Experiments were carried out using the human Müller cell line, MIO-M1. Oxidative stress was induced by exposure to 0.05mM hydrogen peroxide. Complement regulatory protein expression was determined by qPCR and flow cytometry.
Through real-time PCR, we found high levels of CD46 mRNA and moderate levels of CD59 mRNA, whereas CD55 mRNA was undetectable. Flow-cytometry showed moderate expression of CD46 protein and high expression of CD59, CD55 was not detectable. Furthermore, we found moderate levels of C5aR mRNA and a low level of C3aR. At the protein level, both receptors were low in abundance. In MIO-M1 cells treated with 0.5 mM Hydrogen peroxide, both flow cytometry and RT-PCR showed very little or no changes in CD46, CD55 and CD59 levels.
Our studies show that Müller cells express several complement regulatory proteins but their expression levels are not modulated by oxidative stress. These results suggest complement regulation might be different in Müller cells and RPE.
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