GSE135167
Single cell profiling reveals an endothelium-mediated immunomodulatory pathway in the eye choroid
The activity and survival of retinal photoreceptors depend on support functions performed by the retinal pigment epithelium (RPE) and on oxygen and nutrients delivered by blood vessels in the underlying choroid. By combining single cell and bulk RNA sequencing, we categorized mouse RPE/choroid cell types and characterized the tissue-specific transcriptomic features of choroidal endothelial cells. We found that choroidal endothelium adjacent to the RPE expresses high levels of Indian Hedgehog, and identified its downstream target as stromal GLI1+ mesenchymal stem cell-like cells. Genetic impairment of Hedgehog signaling in vivo induced significant loss of choroidal mast cells, as well as an altered inflammatory response and exacerbated visual function defects after retinal damage. Our studies reveal the cellular and molecular landscape of adult RPE/choroid and uncover a Hedgehog-regulated choroidal immunomodulatory signaling circuit. These results open new avenues for the study and treatment of retinal vascular diseases and choroid-related inflammatory blinding disorders. Overall design: Single cell RNAseq experiments (10x Genomics Chromium platform) were performed using RPE/choroid tissue from 90 day-old mice of two different strains, C57BL/6J and B6129PF1/J. For each strain, experiments were carried out with pooled RPE/choroid tissue from one eye from a male and another from a female. Bulk RNAseq: a) tissue-specific endothelial cells isolated from 30 day-old B6129PF1/J mice (3 independent isolations, 7 animals per isolation for neural retina, 1 animal per isolation for lung, liver and heart); b) RPE/choroid tissue from 6 month-old, tamoxifen-treated Ihh+/+ and Ihhi?EC/?iEC mice (3 mice per genotype); c) cultured choroidal GLI1+ cells isolated from Gli1GFP/+ mice and treated with DMSO or 100nM SAG for 24h (3 replicates per treatment).