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Transcriptomic comparison of young and aged choroid at the bulk and single-cell levels (bulk)

ABSTRACT: Purpose: The goals of this study were to identify cell specific expression patterns from infant and aged choroid, with a particular emphasis on how endothelial gene expression changes with age. Methods: Independent libraries were prepared for infant and adult choroidal cells from seventeen human donors. Trephine punch biopsies were used to acquire central RPE and choroidal tissue (infants: 4 mm punch biopsy; adults: 8 mm hemisected punch biopsy). Poly-A selected RNA transcripts underwent 150 base-pair paired-end sequencing with an Illumina HiSeq 2000. Reads were mapped to the human genome hg19 with STAR (version = 020201) and quantified with the featureCounts function from the Rsubread package (version = 1.28.1). Differential expression analysis was performed with edgeR (version = 3.26.8). Results: Differential expression analysis identified genes enriched in infant versus adult libraries. Differentially expressed genes (p-value < 0.00001, FDR < 0.001, cpm >2, logFC > 1) were input into WebGestalt for over-representation analysis. Aged choroidal samples were enriched in proinflammatory genes. Conclusions: This study provides a transcriptomic comparison of infant and aged human donor choroid at the bulk and single-cell levels. The aged choroid, in particular the aged vasculature, is enriched in pro-inflammatory genes.

ORGANISM(S): Homo sapiens

PROVIDER: GSE149099 | GEO | 2020/04/23

REPOSITORIES: GEO

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Project description:Purpose: The goals of this study were to identify cell specific expression patterns from infant and aged choroid, with a particular emphasis on how endothelial gene expression changes with age. Methods: Independent libraries were prepared for infant and adult choroidal cells from four human donors. Macular and peripheral samples from single-cell donors 18-21 were acquired, analyzed, and uploaded in a previous experiment (GSE135922). In single-cell donors 22-25, new reads were acquired from a 12-mm macula-centered punch. Choroidal punches gently dissociated in collagenase II for 1 hours before cryopreservation. Thawed cells were enriched endothelial cells by incubating with anti-CD31-microbeads. Both CD31-positive and CD31-negative libraries from single-cell donors 22-25 were sequenced on an Illumina NovaSeq system. Sequenced reads were mapped to the human genome build hg19 with CellRanger(v3.0.1) and filtered to remove cells likely to be doublets or cells with a high proportion of mitochondrial reads. Libraries from single-cell donors 22-25 were aggregated with donors 18-21 using canonical correlation analysis. Feature selection was performed with the variance stabilizing transformation before integration was performed with Seurat (v3.0.1). Results: A total of 37,070 cells were recovered after filtering with 415,740,738 corresponding reads. A total of 17,229 cells were recovered from infant libraries while 19,841 cells were recovered from the adult libraries. Clusters were assigned to known choroidal cell types based on expression of distinguishing marker genes. Differential expression analysis identified genes enriched in each population of cells originating from infant versus adult libraries. Particular emphasis was given to genes enriched in infant choriocapillaris endothelial cells. Conclusions: This study provides a transcriptomic comparison of infant and aged human donor choroid at the bulk and single-cell levels. The aged choroid, in particular the aged vasculature, is enriched in pro-inflammatory genes.

Project description:The choroid is the vascular layer situated between the outer sclera and the inner retina. Together with the ciliary body and the iris it forms the uvea. Because of its rich blood supply it is also called the nutritive layer and it supplies oxygen and nutrition to the retinal pigment epithelium and the outer retina. Due to its vascular nature it acts as a heat sink and helps in thermoregulation within the eye. It also contains a pigment “melanin”, which absorbs excess light within the eye and prevents scattering. . The human choroid is thickest posteriorly where it measures 0.2 mm, whereas anteriorly it measures 0.1 mm.. The aim of this study was to characterize the choroid proteome to generate a resource for future studies on the choroid . The method used in this study combined bRPLC and LC-MS/MS analysis of the proteins isolated from the three cadaver samples of healthy donors. Subsequently, we classified the proteins based on gene ontology and pathway analysis. A total of 5,249 non redundant proteins were identified in the human choroid. Gene ontology classification pinpointed proteins involved in protein metabolism, regulation of nucleobase, nucleoside, nucleotide and nucleic acid metabolism, transport, cell growth and/or maintenance and immune response. Several proteins identified in normal choroid have previously been identified in human choroid where these proteins are related to glaucoma, ocular inflammation, toxoplasmic retinochoroiditis, diabetic retinopathy, open-angle glaucoma and Grave’s disease. The top canonical pathway in which the choroid proteins participated are EIF2 signaling, integrin signalling, mitochondrial dysfunction, regulation of eIF4 and p70S6K signaling and clathrin-mediated endocytosis signalling. Around 800 choroid proteins were related to infectious diseases. The results of this study illustrate the largest number of proteins identified in human choroid and may serve as a valuable resource for future investigations of choroid biology and disease. Proteomic analysis of choroid proteins could provide versatile information to understand choroidal functions and the underlying pathogenesis of choroidal pathologies.

Project description:Purpose: The goals of this study were to identify cell specific expression patterns of the retinal pigment epithelium (RPE) and a variety of choroidal cell types originating from the macula and the periphery of human donor eyes, with a particular emphasis on identifying expression signatures of choroidal endothelial cells. Methods: Independent libraries were prepared for macular and peripheral samples of combined RPE/choroid from seven donors in two single cell sequencing experiments. In the first experiment, 8-mm macular and peripheral punches of RPE/choroid from Donors 1-3 were digested in papain prior to cryopreservation and subsequent GEM barcoding/library construction. Donors 1-2 had no noted ophthalmologic disease documented, while Donor 3 was diagnosed with age-related macular degeneration. In the second experiment, 12-mm macular and peripheral punches of RPE/choroid from Donors 4-7 were digested in collagenase II prior to cryopreservation, CD31-magentic bead enrichment and subsequent GEM barcoding/library construction. Donors 5-7 had no noted ophthalmologic disease documented, while Donor 4 was diagnosed with age-related macular degeneration. In both experiments, libraries were sequenced on a HiSeq4000. Sequenced reads were mapped to the human genome build hg19 will CellRanger(v3.0.1) and filters removed cells likely to be doublets or cells with a high proportion of mitochondrial reads. Clustering of cells with similar expression profiles was performed with Seurat (v3.0.2). Results: In the first experiment with unenriched RPE/choroid from donors 1-3, we recovered 4,355 cells post filtering with 40,177,477 corresponding reads. A total of 2,167 cells originated from the macula and 2,168 cells originated from the periphery. A total of 11 clusters were identified, and highly enriched genes in each cluster were used to classify clusters into their presumed dominant cell type. Differential expression analysis was performed between cells of macular and peripheral origin in each cluster and between donors with and without a history of age-related macular degeneration. Results: In the second experiment with CD31-enriched RPE/choroid from donors 4-7, we recovered 14,234 cells post filtering with 135,742,297 corresponding reads. A total of 7,647 cells originated from the macula and 6,587 cells originated from the periphery. A total of 8,521 of these cells were presumed endothelial cells. A total of 13 clusters were identified, and highly enriched genes in each cluster were used to classify clusters into their presumed dominant cell type(s). Differential expression analysis was performed between cells of macular and peripheral origin in each cluster and between donors with and without a history of age-related macular degeneration. Within each of the endothelial clusters (Clusters 5-8), differential expression analysis was performed between each cluster and the remaining endothelial cells. Conclusions: This study provides a large atlas of single-cell level gene expression patterns of the human retinal pigment epithelium and choroidal cell types. We identify expression patterns of most expected choroidal cell populations and describe macular versus peripheral regional differences. We additionally identify enriched transcripts in specific cell populations in age-related macular degeneration. We characterize gene expression patterns along the choroidal vascular tree, and identify populations of arterial, capillary, and venous endothelial cells. Our results show that single-cell sequencing can be performed on human RPE/choroid after cryopreservation, and that CD31 magnetic bead enrichment can be employed to enrich for endothelial cells for single-cell sequencing.

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Transcriptomic comparison of young and aged choroid at the bulk and single-cell levels (bulk)

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