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Selina McHarg, Nicole Brace, Rahat Perveen, Graeme C.M. Black, Richard Unwin, Gregory S Hageman, Anthony John Day, Simon John Clark, Paul N Bishop; The expression of complement genes by retinal pigment epithelial cells from donors with and without AMD. Invest. Ophthalmol. Vis. Sci. 2016;57(12):2638.
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© ARVO (1962-2015); The Authors (2016-present)
Aberrant activation of the complement cascade is implicated in the pathogenesis of age-related macular degeneration (AMD), with genetic variation in complement genes known to be a major risk determinant. However, exactly how common variants in complement genes modify AMD risk remains poorly understood. The purpose of this study was to investigate the expression of complement genes in primary cultures of human retinal pigment epithelial (RPE) cells.
RPE cells isolated from adult human eye donor tissue were cultured for 1-2 weeks, and the RNA extracted. Quantitative polymerase chain reaction was used to determine the expression of the genes encoding factor H (FH), factor H-like protein 1 (FHL-1) and the factor H related proteins 1-5 (FHR1-5). Their relative expression was compared in RPE cells derived from donors with and without AMD.
The genes encoding FH and FHL-1 were expressed by cultured human RPE cells. The expression levels in RPE cells derived from unaffected donors were relatively tightly clustered, but those in RPE cells derived from donors with AMD were much more variable and overall expression levels of FH and FHL-1 were both significantly increased, by over 2-fold. The gene encoding FHR3 was weakly expressed in RPE cells derived from subjects both with and without AMD, whilst weak gene expression of FHR1 and 5 was detected only in RPE cells derived from donors with AMD. Expression of the genes encoding FHR2 and FHR4 was not detected in any of the cultured RPE cells.
We demonstrate that primary cultures of human RPE cells express genes encoding FH, FHL-1, FHR1, FHR3 and FHR5; therefore locally derived complement proteins expressed by the RPE are likely to contribute to regulation of the complement system in the macula. The increased variability in expression of genes encoding FH and FHL-1 in RPE cells derived from donors with AMD, compared to those from unaffected donors, could be explained by the underlying genotypes and we are currently genotyping the donor tissue to explore this possibility.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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