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J. A. Matsubara, K. Kurji, J. Z. Cui, D. Harriman, T. Lin, S. Prasad; The Effects of Amyloid Beta on Gene Expression of Human Retinal Pigment Epithelia Cells. Invest. Ophthalmol. Vis. Sci. 2008;49(13):219.
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Amyloid beta deposits in drusen in age-related macular degeneration (AMD), like the amyloid beta deposits in senile plaques of Alzheimer’s disease, are associated with activated complement proteins and cell injury. Amyloid beta and amyloid precursor protein (APP) were also localized to the normal human retina, and increase with age in the retinal pigment epithelial (RPE) cell. Mutations in CFH gene have been suggested to promote complement activation, leading to chronic inflammation in the retina, which may ultimately contribute to disease progression in AMD. This study is to define amyloid beta that may play a role in activation and inhibition of the complement system in AMD.
Human fetal RPE cells were isolated from fetal eyes and were cultured in Dulbecco’s modified Eagle’s medium (DMEM) supplemented with 10% FBS. RPE cells at Passage 6, 12, and 16 were incubated with Aβ1-42 peptide, or its reverse sequence peptides at concentrations of 0.001, 0.01, and 0.3 µM for 13 hours with 1% FBS-containing DMEM to induce gene expression changes. Aβ1-42 peptide was tested by using Enzyme-Linked ImmunoSorbent Assay (ELISA) and Atomic Force Microscopy (AFM). Total RNA from RPE cell cultures was extracted. Quality of RNA was assessed by Agilent technology, followed by real time PCR analysis of 15 genes. Secretion of C3b in the culture supernatant of RPE cells with the treatment of Aβ1-42 peptide was also tested with ELISA.
The gene expression levels of some inflammatory genes, growth factors, cytokines, and related proteins, including C3 and C5 were increased in each of Passage 6, 12 and 16 RPE cells with the treatment of Aβ1-42 peptide. Some gene expression levels were also decreased with the treatment of Aβ1-42 peptide including C4b, C2, Vitronectin, and Vascular Endothelial Growth Factor (VEGF). Secretion of C3b in the culture supernatant of RPE cells with the treatment of Aβ1-42 peptide showed no changes from the controls.
The results indicate that there is altered gene expression of angiogenic, growth factors, and inflammatory genes in beta-amyloid treated RPE cells of various ages as compared to non-treated RPE cells. Consequently, these findings suggest that amyloid beta may: (1) play a role in the pathological deposits in the eye associated with aging and AMD, (2) stimulate complement system activation and subsequent inflammation associated with AMD.
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