Smith Matthew D, Chamling Xitiz, Gill Alexander J, Martinez Hector, Li Weifeng, Fitzgerald Kathryn C, Sotirchos Elias S, Moroziewicz Dorota, Bauer Lauren, Paull Daniel, Gharagozloo Marjan, Bhargava Pavan, Zack Donald J, Fossati Valentina, Calabresi Peter A
Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, United States.
Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, United States.
Front Mol Neurosci. 2022 May 6;15:874299. doi: 10.3389/fnmol.2022.874299. eCollection 2022.
Astrocytes are instrumental in maintaining central nervous system (CNS) homeostasis and responding to injury. A major limitation of studying neurodegenerative diseases like multiple sclerosis (MS) is lack of human pathological specimens obtained during the acute stages, thereby relegating research to post-mortem specimens obtained years after the initiation of pathology. Rodent reactive astrocytes have been shown to be cytotoxic to neurons and oligodendrocytes but may differ from human cells, especially in diseases with genetic susceptibility. Herein, we purified human CD49f astrocytes from induced pluripotent stem cells derived from individual patient and control peripheral leukocytes. We compared TNF and IL1α stimulated human reactive astrocytes from seven persons with MS and six non-MS controls and show their transcriptomes are remarkably similar to those described in rodents. The functional effect of astrocyte conditioned media (ACM) was examined in a human oligodendrocyte precursor cell (OPC) line differentiation assay. ACM was not cytotoxic to the OPCs but robustly inhibited the myelin basic protein (MBP) reporter. No differences were seen between MS and control stimulated astrocytes at either the transcript level or in ACM mediated OPC suppression assays. We next used RNAseq to interrogate differentially expressed genes in the OPC lines that had suppressed differentiation from the human ACM. Remarkably, not only was OPC differentiation and myelin gene expression suppressed, but we observed induction of several immune pathways in OPCs exposed to the ACM. These data support the notion that reactive astrocytes can inhibit OPC differentiation thereby limiting their remyelination capacity, and that OPCs take on an immune profile in the context of inflammatory cues.
星形胶质细胞对于维持中枢神经系统（CNS）的稳态及应对损伤起着重要作用。研究像多发性硬化症（MS）这样的神经退行性疾病的一个主要限制是缺乏急性期获取的人类病理标本，因此研究只能依赖于病理发生多年后获取的尸检标本。已证明啮齿动物的反应性星形胶质细胞对神经元和少突胶质细胞具有细胞毒性，但可能与人类细胞不同，尤其是在具有遗传易感性的疾病中。在此，我们从个体患者和对照外周血白细胞来源的诱导多能干细胞中纯化出人类CD49f星形胶质细胞。我们比较了来自7名MS患者和6名非MS对照的肿瘤坏死因子（TNF）和白细胞介素1α（IL1α）刺激的人类反应性星形胶质细胞，发现它们的转录组与啮齿动物中描述的转录组非常相似。在人类少突胶质细胞前体细胞（OPC）系分化试验中检测了星形胶质细胞条件培养基（ACM）的功能作用。ACM对OPC没有细胞毒性，但强烈抑制髓鞘碱性蛋白（MBP）报告基因。在转录水平或ACM介导的OPC抑制试验中，MS和对照刺激的星形胶质细胞之间没有差异。接下来，我们使用RNA测序来探究在受到人类ACM抑制分化的OPC系中差异表达的基因。值得注意的是，不仅OPC分化和髓鞘基因表达受到抑制，而且我们观察到暴露于ACM的OPC中几种免疫途径的诱导。这些数据支持这样一种观点，即反应性星形胶质细胞可以抑制OPC分化，从而限制其髓鞘再生能力，并且在炎症信号的背景下，OPC呈现出免疫特征。
