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Atsushi Mukai, Jun Yamada, Hiroki Hatanaka, Tetsuya Yamagishi, Kenji Nagata, Morio Ueno, Junji Hamuro, Shigeru Kinoshita; The role of cell-to-cell interaction through extracellular microvesicles, microRNA, and exosomes in deregulated functions of retinal pigment epithelium and macrophages. Invest. Ophthalmol. Vis. Sci. 2014;55(13):622.
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© ARVO (1962-2015); The Authors (2016-present)
Macrophages (Mps) and retinal pigment epithelium (RPE) cells play key roles in dictating the diverse stages of pathological inflammation involved in age-related macular degeneration (AMD), and are composed of the functionally distinct (or distinctly activated) populations. Here we investigated the interplay between Mps and RPE in the production of senescence-associated secretory phenotype (SASP) and microRNA (miR) in relation to exosome secretion.
The oxidized LDL (ox-LDL) or TNF-α (with or without TGF-β)-induced production of MCP-1, IL-6, and VEGF and the fibrosis of RPE induced in the presence TGF-β/TNF-α , as well as the concurrent reduction of RPE phagocytic activity, were evaluated. During the culture, the supernatants were analyzed for the profiles of secreted miR by microarray (3D-Gene™; Toray Industries, Inc, Tokyo, Japan). Exosome content was measured by use of the ExoScreen system by Dr. Nobuyoshi Kosaka at the National Cancer Research Center Institute, Tokyo, Japan. Apoptotic body, microvesicles, and exosomes were separated by centrifugation at g-forces (g) of 2,000g, 12,000g, and 100,000g, respectively.
Integral PCR array assays of gene signatures induced by TGF-β/TNF-α exposed to ARPE19 revealed clear elevation of collagen 1A, collagen 3A, fibronectin (senescence and EMT-related), snail, wnt5A,wnt5B (EMT-related), and collagen 1A, IL1, snail, and VEGF-A (fibrosis related). Production of both VEGF-A and IL-6 were augmented by ox-LDL in the same culture system, but not by LDL, indicating Mps-RPE interplay. microRNA (miR) 19a/b, 26a/b, 30 ,200, 202, and 211 were increasingly secreted in the culture by degenerated RPE with TGF-β/TNF-α, whereas let 7, 99a/b, 130, 181 and 193, 1273c were decreasingly produced after degeneration, indicating the presence of still unknown roles of miR in the generation of the vicious inflammatory cycle between RPE and Mps. The roles of these miR in regulating the phagocytic activity of RPE of the retinal outer segment are under investigation.
The vicious cycle of inflammation and the resultant fibrosis of RPE might be responsible for the Mps and RPE interplay mediated by miR and the SASP-related mediators MCP-1, VEGF-A, IL-6, TGF-β, and TNF-α, thus proposing a possible new molecular target for future medications.
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