Iba Michiyo, Lee Yeon-Joo, Horan-Portelance Liam, Chang Katherine, Szabo Marcell, Rissman Robert A, You Sungyong, Masliah Eliezer, Kim Changyoun
Molecular Neuropathology Unit, Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, MD 20892, USA.
Departments of Urology and Computational Biomedicine, Cedars-Sinai Medical Center, Los Angeles, CA, USA; Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA.
Brain Behav Immun. 2025 Jan;123:254-269. doi: 10.1016/j.bbi.2024.09.016. Epub 2024 Sep 14.
Synucleinopathies are age-related neurological disorders characterized by the abnormal accumulation of α-synuclein (α-syn) in neuronal and non-neuronal cells. It has been proposed that microglial cells play an important role in synucleinopathy neuroinflammation, as well as homeostatically, such as in the clearance of α-syn aggregates in the brain. Here, we examined the effects of microglia on the pathogenesis of synucleinopathies by cell depletion in a mouse model of synucleinopathies. For this purpose, we treated non-transgenic (Non-tg) and α-synuclein transgenic (α-syn-tg) mice with pexidartinib (PLX3397), a tyrosine kinase inhibitor of colony-stimulating factor 1 receptor (CSF-1R). Neuropathological and immunoblot analysis confirmed that Iba-1 immunoreactive microglial cells were decreased by 95% following PLX3397 treatment in Non-tg and α-syn-tg mice. The level of total α-syn in the Triton X-insoluble fraction of brain homogenate was significantly decreased by microglial depletion in the α-syn-tg mice, while the level of Triton X-soluble human α-syn was not affected. Furthermore, the number of p-α-syn immunoreactive inclusions was reduced in α-syn-tg mice treated with PLX3397. Microglial depletion also ameliorated neuronal and synaptic degeneration in α-syn-tg mice, thereby resulted partially improving the motor behavioral deficit in α-syn-tg mice. Moreover, we demonstrated that microglia that survived post-PLX3397 treatment (PLX-resistant microglia) have lower expressions of CSF-1R, and microglial transcriptome analysis further elucidated that PLX-resistant microglia have unique morphology and transcriptomic signatures relative to vehicle-treated microglia of both genotypes; these include differences in definitive microglial functions such as their immune response, cell mobility, cell-cell communications, and regulation of neural homeostasis. Therefore, we suggest that microglia play a critical role in the pathogenesis of synucleinopathies, and that modulation of microglial status might be an effective therapeutic strategy for synucleinopathies.
突触核蛋白病是与年龄相关的神经疾病，其特征是α-突触核蛋白（α-syn）在神经元和非神经元细胞中异常积累。有人提出，小胶质细胞在突触核蛋白病神经炎症以及稳态中发挥重要作用，例如在清除大脑中的α-syn聚集体方面。在此，我们通过在突触核蛋白病小鼠模型中进行细胞耗竭来研究小胶质细胞对突触核蛋白病发病机制的影响。为此，我们用培西达替尼（PLX3397），一种集落刺激因子1受体（CSF-1R）的酪氨酸激酶抑制剂，处理非转基因（Non-tg）和α-突触核蛋白转基因（α-syn-tg）小鼠。神经病理学和免疫印迹分析证实，在Non-tg和α-syn-tg小鼠中，PLX3397处理后，Iba-1免疫反应性小胶质细胞减少了95%。α-syn-tg小鼠脑匀浆的Triton X不溶性部分中总α-syn水平因小胶质细胞耗竭而显著降低，而Triton X可溶性人α-syn水平未受影响。此外，用PLX3397处理的α-syn-tg小鼠中p-α-syn免疫反应性包涵体的数量减少。小胶质细胞耗竭还改善了α-syn-tg小鼠的神经元和突触退化，从而部分改善了α-syn-tg小鼠的运动行为缺陷。此外，我们证明PLX3397处理后存活的小胶质细胞（PLX抗性小胶质细胞）CSF-1R表达较低，小胶质细胞转录组分析进一步阐明，相对于两种基因型的载体处理的小胶质细胞，PLX抗性小胶质细胞具有独特的形态和转录组特征；这些包括在明确的小胶质细胞功能方面的差异，如它们的免疫反应、细胞迁移、细胞间通讯以及神经稳态调节。因此，我们认为小胶质细胞在突触核蛋白病发病机制中起关键作用，并且调节小胶质细胞状态可能是突触核蛋白病的一种有效治疗策略。
