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J. Tombran–Tink, V, M. Liu, S.S. M. Zhang, C.J. Barnstable; The Retinal Pigment Epithelium Express a Wide Range of Inflammatory Proteins and Hematopoietic Markers . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4862.
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© ARVO (1962-2015); The Authors (2016-present)
RPE cells form part of the blood retina barrier where they can potentially regulate inflammatory responses. In this study we examined the expression of genes associated with inflammatory/immune processes to understand the role of RPE cells in immune diseases of the eye.
ARPE–19 were grown in RPMI containing 2% FBS. RNA was isolated from the cells with TRIzol and purified using Rneasy (Qiagen). RNA with 280/260 ratio greater than 1.9 was labeled using the 3DNA Array 900 Kit (Genisphere). Cy3 and Cy9 labeled probes were hybridized to QuantArray–Human OHU28K oligo arrays which were then scanned on a GenePix 4000A scanner to be analysed using GenePix software Version 4.0 (Axon Instruments). Gene clustering was done with Cluster v2.20 and TreeView v1.60 software (EisenLab, UC Berkley), and GO classification performed using LocuLink database (NCBI). Thresholds were > 2–fold expression changes in at least three arrays.
Several large clusters of genes that play an important role in the induction and regulation of immune/inflammatory responses were expressed in the RPE cells. These include surface glycoproteins involved in T–cell activation and proliferation, chemokines involved in leukocyte recruitment and regulation of chronic inflammation, Complement components, Interleukins, T cell activation proteins, and Macrophage Differentiation Factors. The RPE cells also expressed a cluster of chemokine receptors and a large group of G–protein coupled receptors associated with immune function. Other large clusters of receptors including IFN, IL, leucocyte, and NK cell immunoglobulin receptors were also expressed by the RPE. A group of 5 Toll–like receptors that play a central role in pathogen recognition and activation of innate immunity were detected on the RPE arrays as well.
The results show that several potent inflammatory mediators and hematopoietic cell markers are expressed by RPE cells and provide evidence that the pigmented epithelium may regulate immune responses during ocular inflammation. These expression markers may also aid in the identification of RPE cells during pathological processes in the eye.
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