DataSheet_1_In-Depth Molecular Profiling Specifies Human Retinal Microglia Identity.pdf

Microglia are the tissue-resident macrophages of the retina and brain, being critically involved in organ development, tissue homeostasis, and response to cellular damage. Until now, little is known about the molecular signature of human retinal microglia and how it differs from the one of brain microglia and peripheral monocytes. In addition, it is not yet clear to what extent murine retinal microglia resemble those of humans, which represents an important prerequisite for translational research. The present study applies fluorescence-activated cell sorting to isolate human retinal microglia from enucleated eyes and compares their transcriptional profile with the one of whole retinal tissue, human brain microglia as well as classical, intermediate and non-classical monocytes. Finally, human retinal microglia are compared to murine retinal microglia, isolated from Cx3cr1GFP/+ mice. Whereas human retinal microglia exhibited a high grade of similarity in comparison to their counterparts in the brain, several enriched genes were identified in retinal microglia when compared to whole retinal tissue, as well as classical, intermediate, and non-classical monocytes. In relation to whole retina sequencing, several risk genes associated with age-related macular degeneration (AMD) and diabetic retinopathy (DR) were preferentially expressed in retinal microglia, indicating their potential pathophysiological involvement. Although a high degree of similarity was observed between human and murine retinal microglia, several species-specific genes were identified, which should be kept in mind when employing mouse models to investigate retinal microglia biology. In summary, this study provides detailed insights into the molecular profile of human retinal microglia, identifies a plethora of tissue-specific and species-specific genes in comparison to human brain microglia and murine retinal microglia, and thus highlights the significance of retinal microglia in human retinal diseases and for translational research approaches.

小胶质细胞（microglia）是视网膜与大脑中的组织驻留巨噬细胞，在器官发育、组织稳态及细胞损伤应答中发挥关键调控作用。迄今为止，学界对人视网膜小胶质细胞的分子特征，以及其与大脑小胶质细胞、外周单核细胞的差异尚缺乏充分认知。此外，小鼠视网膜小胶质细胞与人类同源细胞的相似程度尚不明确，而这一问题正是转化研究的重要前提之一。本研究通过荧光激活细胞分选（fluorescence-activated cell sorting）从摘除眼球中分离人视网膜小胶质细胞，并将其转录谱与全视网膜组织、人脑小胶质细胞及经典型、中间型、非经典型单核细胞的转录谱进行对比分析。最后，本研究还将人视网膜小胶质细胞与从Cx3cr1GFP/+小鼠中分离得到的小鼠视网膜小胶质细胞进行了比较。尽管人视网膜小胶质细胞与大脑中的同源细胞具有高度相似性，但相较于全视网膜组织及经典型、中间型、非经典型单核细胞，视网膜小胶质细胞中存在多个富集表达的基因。相较于全视网膜测序数据，多个与年龄相关性黄斑变性（age-related macular degeneration, AMD）、糖尿病视网膜病变（diabetic retinopathy, DR）相关的风险基因在视网膜小胶质细胞中呈优先表达模式，提示其在疾病病理生理过程中的潜在作用。尽管人与小鼠的视网膜小胶质细胞之间存在高度相似性，但本研究仍鉴定出多个物种特异性基因，这提示在利用小鼠模型研究视网膜小胶质细胞生物学特性时需注意这一差异。综上，本研究系统阐明了人视网膜小胶质细胞的分子特征谱，相较于人脑小胶质细胞与小鼠视网膜小胶质细胞，鉴定出诸多组织特异性及物种特异性基因，从而明确了视网膜小胶质细胞在人类视网膜疾病及转化研究中的重要意义。