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Maria E. Marin Castano, Marianne Pons; Angiotensin II upregulates MCP-1 Expression through the NF-B Pathway in Human Retinal Pigment Epithelium. Invest. Ophthalmol. Vis. Sci. 2012;53(14):6546.
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Choroidal neovascularization (CNV) is a critical pathogenesis in age-related macular degeneration (AMD). Wet AMD is always preceded by early disease. However, the underlying mechanism behind the progression of early AMD to CNV remains unclear. The pathogenesis of AMD is multifactorial, and hypertension (HTN) has been implicated. We postulate that HTN-associated hormone angiotensin II (Ang-II), through interactions with its two cell surface receptors (AT1 and AT2), will regulate molecules important in inflammation, especially the pro-inflammatory monocyte chemoattractant protein (MCP-1) contributing to CNV. Moreover, given that MCP-1 possesses an NF-kB binding site in its promoter region and is known to be controlled by NF-kB activation, the regulation of MCP-1 by Ang II could be NF-kB mediated. We have previously demonstrated that human and murine retinal pigment epithelium (RPE) express both Ang II receptors and that Ang-II significant dysregulates RPE extracellular matrix (ECM) turnover, providing helpful insight into sub-RPE deposits formation. To better understand the involvement of the HTN in the progression of early AMD to CNV, we investigated whether Ang II modulates MCP-1 production in the RPE and whether this modulation requires AT1 receptor interaction and NF-ΚB activation.
Confluent RPE cells were treated with Ang II (10-7M) for different times. In some experiments, in addition to Ang II, cells were exposed to10-7M candesartan, an Ang II type 1 (AT1) receptor blocker, 10-7M PD123319 (PD), an Ang II type 2 (AT2) receptor blocker, combination of both inhibitors, NF-kB inhibitor PDTC (10-7M) and/or IkB-a phosphorylation inhibitor Bay11-7082 (5mM) for 1 hour or 30 minutes before they were exposed to Ang II. Total RNA and proteins were extracted. MCP-1 expression and production was evaluated by real-time PCR and ELISA. IΚB, and p65 transcription factor expression was examined by Western blot.
Ang II upregulated MCP-1 expression and secretion by RPE cells through AT1 receptor interaction and NF-ΚB activation.
Our data support the hypothesis that Ang II, through MCP-1, may regulate recruitment of macrophages to sub-RPE deposits and into the choriocapillaris, which can release additional cytokines and mediators to amplify the progression of early AMD to CNV, suggesting a pathogenic mechanism to explain the link between HTN and AMD.
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