Deep RNA-sequencing of the RPE Reveals a Suppressed Innate Immune Response and Activation of Dedifferentiation Pathway in Response to Chronic Smoking

Cigarette smoking is the strongest environmental risk factor for developing age-related macular degeneration (AMD), the most common cause of blindness among the elderly in western societies. Despite intensive study, the full impact of smoking on the retinal pigment epithelium (RPE), a central cell type involved in AMD pathobiology, remains unknown. The relative contribution of the known dysfunctional pathways to AMD, at what stage they are most pathogenic, or whether other processes are relevant, is poorly understood, and furthermore, whether they are activated by smoking, is unknown. We performed global RNA-sequencing of the RPE from C57BL/6J mice exposed to chronic cigarette smoke or air for 6 months to identify potential pathogenic and cytoprotective pathways. The RPE transcriptome induced by chronic cigarette smoking exhibited a mixed response of marked suppression of the innate immune response that included the antiviral response with type I and II interferons concurrent with upregulation of cell differentiation and morphogenic gene clusters, suggesting an attempt by the RPE to maintain its differentiated state despite smoke-induced injury. Given that mice exposed to chronic smoke develop early features of AMD, these novel findings are potentially relevant to the transition from aging to AMD. PolyA RNA from RPE/choroid using triplicate biological replicates for filtered air or smoking exposure were sequenced. Note: one filtered air replicate was eliminated from analysis for excessive neural retina tissue contamination.

吸烟是诱发年龄相关性黄斑变性（age-related macular degeneration, AMD）的最强环境危险因素，而AMD是西方社会老年人失明的最常见病因。视网膜色素上皮（retinal pigment epithelium, RPE）是参与AMD发病机制的核心细胞类型，尽管已有大量深入研究，但吸烟对RPE的完整影响仍不明确。目前学界对已知功能异常通路在AMD发生中的相对贡献、其发挥致病作用的关键阶段、是否存在其他相关病理过程，以及这些通路是否可被吸烟激活等问题，均知之甚少。本研究对暴露于慢性香烟烟雾或洁净空气达6个月的C57BL/6J小鼠的RPE开展全转录组RNA测序，以筛选潜在的致病及细胞保护通路。慢性香烟烟雾诱导的RPE转录组呈现出混合应答特征：显著抑制天然免疫应答（涵盖I型、II型干扰素介导的抗病毒应答），同时上调细胞分化与形态发生基因簇，这提示RPE试图在烟雾诱导的损伤下维持自身分化状态。鉴于暴露于慢性烟雾的小鼠会出现AMD早期病理特征，本研究的全新发现或与衰老向AMD的病理转化密切相关。本研究对洁净空气暴露组与烟雾暴露组的RPE/脉络膜样本（每组设置3次生物学重复）的聚腺苷酸RNA（PolyA RNA）进行了测序。注：因存在过量神经视网膜组织污染，洁净空气暴露组的1次生物学重复被排除于数据分析之外。