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Han Si, Cristhian A Urzua, Baoying Liu, Zhiyu Li, Amol Sura, adrianna lee, Robert B Nussenblatt; Whole transcriptome profiling of peripheral CD4+ T-cells in age-related macular degeneration patients using RNA-seq. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):820.
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© ARVO (1962-2015); The Authors (2016-present)
To examine whether the adaptive immune system plays a role in age-related macular degeneration (AMD)
In total 83 age-matched samples of peripheral blood mononuclear cells (PBMCs) were collected from patients and healthy donors. In the present study, total RNAs were isolated from beads-purified CD4+ T-cells from 6 large drusen (age: 68.3±9.8) and 4 healthy donors (age: 72.0±4.5). Raw reads from Hiseq2000 were mapped to the human reference sequence (Hg19) by TopHat2 and differentially expressed genes were tested using DESeq2, in which significance was tested using Wald statistics and p values were adjusted by BH method.
Previously we have observed that PBMCs from large drusen patients showed significant immune response in response to one of the synthetic peptides of soluble antigen. In the current study, the patients and healthy donors are also clearly separated in a principle component analysis using expression data of all the genes from RNA-seq (PC1: 34% variance). The data show 434 up-regulated (≥1.4 fold) and 543 down-regulated (≥1.5 fold) genes in patients (adj.p<0.05). Genes encoding certain cytokines and chemokines and their receptors show significant difference, e.g., up-regulation of CCR2, IL6R, IL16, CXCR7 and down-regulation of IL8, IL20R, CCR4, CCR6, CXCR4, CXCR6 in patients. Analysis in Ingenuity Pathway further reveal that genes dysregulated in patients are enriched in the PI3K/AKT, TNFR2 signaling, antioxidant action of vitamin C pathways etc. Dysregulated genes are also enriched in biofunctions of cell cycle regulation, immune cell trafficking, cellular growth and proliferation. More interestingly, CD28, usually reduced in aging T-cells, is significantly less expressed in patients than in healthy donors. Accordingly, patients show significantly more CD28- T-cells than donors (p=0.03, Mann-Whitney test) from flow cytometry analysis, suggesting more skewed T-cell repertoire to CD28- subset in patients, thereby possibly more profound immunosenescence in patients than in healthy donors.
Since RNA-seq data has shown moderate but significant differences at gene expression level and dysregulation in multiple pathways and biofunctions in CD4+ T-cells between patients and controls, the adaptive immune system thus may play important roles in AMD disease progression.
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