TOP ＞ シンポジウム

シンポジウム 14 ヒトミクログリアによる脳の生理及び病態生理機能制御機構の解明 14 Elucidation of physiological and pathological brain function by human microglia. 座長：中島 欽一（九州大学・院医）・Parajuli Bijay（山梨大・院医・薬理） 2022年6月30日　9:02～9:30　沖縄コンベンションセンター 劇場棟　第1会場 1S01m-01 ミクログリアからニューロンへの直接分化転換とその脳梗塞治療への応用 Direct conversion of microglia into neurons and its therapeutic application to ischemic brain injury *中島 欽一(1)、入江 剛史(1)、松田 花菜江(1)、松田 泰斗(1) 1. 九州大学 *Kinichi Nakashima(1), Takashi Irie(1), Kanae Matsuda-Ito(1), Taito Matsuda(1) 1. Kyushu University Keyword: Microglia, Neuron, Direct reprogramming, Stroke Usefulness of neural stem cell (NSC) transplantation to replenish lost neurons has been extensively investigated. We have previously shown that human iPSC-derived NSCs efficiently give rise to neurons in the injured spinal cord, inducing recovery of locomotor functions of mice after injury. Although it has been already recognized that supply of new neurons has beneficial effects on the functional recovery after injury in the nervous systems, there still remain critical problems, such as tumorigenicity and time-consuming preparation of cells if we utilize iPSC-derived cells. As an alternative strategy to replenish new neurons in vivo, direct conversion from endogenous cells in non-neuronal lineages has recently attracted much attention. In this regard, we have found that microglia, which converge at lesion site after injury, can be converted to functional neurons both in vitro and in vivo by the expression of a single proneural transcription factor NeuroD1. In this talk, we will demonstrate that this microglia-to-neuron conversion reinstates neurological function after stroke, shedding light on the development of therapies for ischemic brain injury by in situ neuronal conversion technology. 2022年6月30日　9:30～9:58　沖縄コンベンションセンター 劇場棟　第1会場 1S01m-02 Development of novel transplantation method for studying physiological and pathological role of human induced pluripotent stem cell-derived microglia in immunocompetent mice brain *Bijay Parajuli(1,2), Schuichi Koizumi(1,2) 1. Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, 2. GLIA Center, University of Yamanashi Keyword: microglia, human microglia, transnasal transplantation Microglia are an immune cell type in the central nervous system. They play essential roles in controlling neural circuit development, modulating neurotransmission, and maintaining brain homeostasis. Most of our current understanding of microglial function in physiological and pathological brain is achieved from experiments performed in rodents like mouse. Because characteristic features in microglia differ between mice and humans, experiments performed on mouse microglia do not always represent the response of human microglia. To overcome this gap, research on primary human microglia is usually performed in vitro by isolating human microglia from brain tissue, either removed during the surgical resection of a brain, or taken from a postmortem brain. However, experiments performed in vitro do not always accurately represent in vivo characteristics of microglia. To elucidate the in vivo characteristics of human microglia, we developed a simplified method to generate induced pluripotent stem cell-derived human microglia (iPSMG) and transplant them into the brain via a transnasal route in immunocompetent mice, in combination with a colony stimulating factor 1 receptor (CSF1R) antagonist. We show that by combining pharmacological ON/OFF of a CSF1R antagonist PLX5622 and intranasal transplantation, iPSMG can be non-invasively transplanted into the mouse brain; the transplanted iPSMG can migrate to each brain site, proliferate and be engrafted for at least 60 days without any immunosuppressants. Our method provides a way to non-invasively transplant cells into mouse brain and therefore is valuable for evaluating how human microglia affect physiological and pathological brain functions. 2022年6月30日　9:58～10:28　沖縄コンベンションセンター 劇場棟　第1会場 1S01m-03 ヒトiPS細胞からミクログリアの分化誘導法開発および疾患モデリング Generating Microglia from Human iPS cells and Disease Modeling *孫 怡姫(1)、渡部 博貴(1)、森本 悟(1)、岡野 栄之(1) 1. 慶應義塾大学 *Iki Sonn(1), Hirotaka Watanabe(1), Satoru Morimoto(1), Hideyuki Okano(1) 1. Keio University Keyword: iPS, microglia, neurodegenerative diseases Microglia are innate immune cells that are the only residential macrophages in the central nervous system. They play vital physiological roles in the adult brain and during development. They are now particularly in the spotlight because many genetic risk factors recently identified for neurodegenerative diseases are largely expressed in microglia. Rare polymorphisms in these risk alleles lead to abnormal activity of microglia under traumatic or disease conditions. Considering species differences and a limited accessibility to human specimens, there is a thirsty need to explore a new resource of human microglia. Here we show that a large number of human microglia-like cells (hiMGLs) can be derived from hiPSCs by a novel method, using overexpression of one pivotal transcription factor during microglia development. These hiMGLs showed extremely similar features of primary microglia as scrutinized by transcriptome analysis and exhibited characteristics closer to in vivo microglia when co-cultured with mouse primary neurons. We also confirmed that these hiMGLs can be transplanted and stayed in mouse brain through nasal transplantation. While disease conditions, such as AD, would disrupt and dysregulate the defensive function of microglia, what intrigued most scientists’ interests was that multiple genes that were specifically expressed in microglia have been identified as pathogenic clues or risk genes in various neurodegenerative diseases, especially TREM2 in AD. In this study, we generated hiMGLs from Nasu-Hakola Disease's patients, as well as hiPSCs with mutations on TREM2 and APOE genes, trying to figure out the pathological mechanism. In addition, regarding these data, one can wonder if inflammasome formation would be impaired in microglia with TREM2 mutation. Overall, our newly developed method for deriving human microglia cells can potentially be applied to transplantation into brain organoids or animal brains to create more relevant experimental models for disease research or for studying the physiology of microglia. This technology would accelerate the research to recapitulate the in vivo signatures of human microglia. 2022年6月30日　10:28～10:58　沖縄コンベンションセンター 劇場棟　第1会場 1S01m-04 HUMAN MICROGLIAL APOE and ALZHEIMER’S DISEASE *Huaxi Xu(1) 1. Institute for Brain Science and Disease, Chongqing Medical University, China Keyword: Microglia, Astrocytes, APOE, Alzheimer’s Disease Microglia are increasingly implicated in aging and Alzheimer’s disease (AD). Recently we establish isogenic human ESC–derived microglia-like cell lines (hMGLs) harboring AD variants in CD33, INPP5D, SORL1, and TREM2 loci and curate a comprehensive atlas comprising ATAC-seq, ChIP-seq, RNA-seq, and proteomics datasets. Using this modeling and analysis platform for human microglia, we provide new insight into epistatic interactions in AD genes and show convergence of microglial AD genes at the APOE locus. APOE is abundantly expressed in astrocytes under physiological conditions and dramatically increased in microglia. However, whether microglial APOE exert different functions remains largely elusive. Here, we purified APOE particles derived from primary astrocytes and microglia including hMGLs, and integrate proteomic and lipidomic analysis and neuronal and glial functional test. We found that microglial APOE is more stable than astrocytic APOE, and the size of microglial APOE particles differs from that of astrocytes. In addition, we found that microglial APOE particles are more neurotoxic and more potent in inhibiting microglial migration and phagocytosis of Aβ. Further, microglial APOE particles altered homeostasis of microglia and astrocyte, and impaired mouse cognitive function. Together, our study demonstrates distinct functions of microglial APOE and provides new insights into the contribution of microglial APOE to AD pathogenesis.