Transcriptomes of ATG7 Knockout Microglia

Multiple Sclerosis (MS) is a leading cause of incurable progressive disability in young adults caused by inflammation in the central nervous system (CNS) that triggers demyelination, glial cell dysfunction and irreversible neuro-axonal damage1. While considerable progress has been made in treating early inflammatory relapsing-remitting MS, the mechanisms underpinning the progressive stage remain largely unknown. The capacity of microglia, the CNS-resident phagocytes, to clear tissue debris is essential for both maintaining and restoring CNS homeostasis2,3 and this capacity diminishes with age4-6. Age strongly associates with the risk of developing progressive MS7,8. Herein we demonstrate that the recovery from inflammation is dependent on the ability of microglia to clear tissue debris and that blocking this process leads to development of progressive disease in a murine model of MS. Microglia-specific deletion of the general autophagy regulator Atg7, but not the canonical macroautophagy protein Ulk1, led to increased intracellular accumulation of phagocytosed myelin. This further associated with the alteration of the microglial phenotype towards that previously described in other neurodegenerative diseases2,3,9. Moreover, Atg7 deficient microglia showed striking similarities with microglia from aged wild type mice, which also demonstrated accumulation of myelin debris and inability to recover from MS-like disease. In contrast, the induction of autophagy using the disaccharide Trehalose in aged mice led to functional myelin clearance and remission from MS-like disease. Our results demonstrate that a non-canonical form of autophagy in microglia is responsible for myelin clearance and that impairment of this pathway markedly changes microglial phenotype and prevents recovery from MS-like disease. Importantly, we show that using a disaccharide ubiquitously found in plant-derived foods to boost autophagy in cells in which this process is naturally diminished can be utilized for therapeutic purposes.Project was run on 4 lanes with a 10M sequencing depth Overall design: Transcriptome sequencing of WT and ATG7 knockout microglia during EAE on young and old mice.

多发性硬化症（Multiple Sclerosis, MS）是青年人群中不可治愈的进行性残疾的首要诱因，其由中枢神经系统（central nervous system, CNS）炎症反应引发，该炎症可诱发脱髓鞘、胶质细胞功能异常以及不可逆的神经轴突损伤¹。尽管在治疗早期炎症性复发缓解型多发性硬化症方面已取得显著进展，但支撑疾病进行性阶段的核心机制仍未被完全阐明。
小胶质细胞（microglia）作为中枢神经系统驻留的吞噬细胞，其清除组织碎片的能力对维持及恢复中枢神经系统稳态至关重要2,3，而该能力会随年龄增长而衰退4-6。年龄与进行性多发性硬化症的发病风险显著相关7,8。
本研究证实，炎症消退依赖于小胶质细胞清除组织碎片的能力，而阻断该过程可在多发性硬化症小鼠模型中诱导进行性疾病的发生。特异性敲除小胶质细胞中的通用自噬调控因子Atg7（而非经典巨自噬蛋白Ulk1），会导致吞噬的髓鞘在细胞内的积累量显著升高。这进一步伴随小胶质细胞表型向其他神经退行性疾病中已报道的表型发生转变2,3,9。此外，Atg7缺陷型小胶质细胞与老年野生型小鼠的小胶质细胞表现出显著相似性，后者同样存在髓鞘碎片积累，且无法从类多发性硬化症中恢复。
与之相反，在老年小鼠中使用二糖海藻糖（Trehalose）诱导自噬，可实现功能性髓鞘清除，并使类多发性硬化症得到缓解。本研究结果表明，小胶质细胞中的非经典自噬途径负责髓鞘清除，而该途径受损会显著改变小胶质细胞表型，并阻碍类多发性硬化症的恢复进程。值得注意的是，本研究证实，利用植物源食物中普遍存在的二糖来增强自噬功能减弱细胞的自噬过程，可用于相关疾病的治疗。
本实验采用4个测序泳道，设置10M测序深度。整体实验设计：对年轻与老年小鼠在实验性自身免疫性脑脊髓炎（Experimental Autoimmune Encephalomyelitis, EAE）模型期间的野生型（wild type, WT）与ATG7敲除小胶质细胞进行转录组测序。