Abstract
Purpose :
The changes in gene expression induced by exposure to advanced glycation end products (AGEs) and lipid peroxidation end products (LPEs) in the human retinal pigment epithelium (hRPE) are still not fully understood. We characterized the whole transcriptome response of hRPE using an in vitro model of exposure to AGEs and LPEs.
Methods :
Human fetal RPE from two independent donors were cultured until full confluency on extracellular matrix (ECM) either previously exposed to glycoaldehyde to induce glycation end products (AGEs) or exposed to malondialdehyde in the culture media to induce lipid peroxidation (LPE). Control cells were exposed to neither AGEs nor LPEs. RNA sequencing gene expression profiling was performed on Illumina HiSeq 2000 platform using paired-end sequencing, followed by mapping to the human reference genome with TopHat2 version 1.3.0. Differential expression analysis was performed following DESeq2 automatic independent filtering enabling testing of all levels of the condition factor.
Results :
Up to 62.8 × 106 high quality reads per sample were aligned to human reference genome. The overall hfRPE transcriptional profile showed significant overlapping with reported highly expressed hRPE genes (P < 2.2 × 10-16). There were 42 differentially expressed genes (DEGs) highlighted in response to AGEs and 87 DEGs in response to LPEs. Of these, 18 and 44 genes were up-regulated in AGEs and LPEs conditions respectively, whereas 24 and 43 genes were down-regulated in the respective conditions. The profile revealed by 12,211 corrected genes showed the overall transcriptional response of hRPE to AGEs positively correlated with the response to LPEs (ρ = 0.46, P < 2.2 × 10-16). DEGs in response to both AGEs and LPEs have roles predominantly in regulation of angiogenesis and include VEGFA and PLXNA4. GO analysis confirmed angiogenesis as one of the terms significantly enriched with upDEGs, along with cytokine activity, response to external stimuli/cytokines and regulation of apoptosis.
Conclusions :
There is a strong positive correlation between the transcriptional response of hRPE to AGEs and LPEs, converging on up-regulation of angiogenesis. The findings point to key RPE genes responding to age-related stress that may be selected as novel therapeutic targets for AMD.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.