Bulk and single-cell gene expression analyses reveal aging human choriocapillaris has pro-inflammatory phenotype

The human choroidal vasculature is subject to age-related structural and gene expression changes implicated in age-related macular degeneration (AMD). In this study, we performed both bulk and single-cell RNA sequencing on infant (n = 4 for bulk experiments, n = 2 for single-cell experiments) and adult (n = 13 for bulk experiments, n = 6 for single-cell experiments) human donors to characterize how choroidal gene expression changes with age. Differential expression analysis revealed that aged choroidal samples were enriched in genes encoding pro-inflammatory transcription factors and leukocyte transendothelial cell migration adhesion proteins. Such genes were observed to be differentially expressed specifically within choroidal endothelial cells at the single-cell level. Immunohistochemistry experiments support transcriptional findings that CD34 is elevated in infant choriocapillaris endothelial cells while ICAM-1 is enriched in adults. These results suggest several potential drivers of the pro-inflammatory vascular phenotype observed with advancing age.