Makarava Natallia, Safadi Tarek, Bocharova Olga, Mychko Olga, Pandit Narayan P, Molesworth Kara, Baiardi Simone, Zhang Li, Parchi Piero, Baskakov Ilia V
Center for Biomedical Engineering and Technology and.
Department of Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland, USA.
J Clin Invest. 2024 Oct 3;134(23):e181169. doi: 10.1172/JCI181169.
Microglia are recognized as the main cells in the central nervous system responsible for phagocytosis. The current study demonstrates that in prion disease, microglia effectively phagocytose prions or PrPSc during early preclinical stages. However, a critical shift occurred in microglial activity during the late preclinical stage, transitioning from PrPSc uptake to establishing extensive neuron-microglia body-to-body cell contacts. This change was followed by a rapid accumulation of PrPSc in the brain. Microglia that enveloped neurons exhibited hypertrophic, cathepsin D-positive lysosomal compartments. However, most neurons undergoing envelopment were only partially encircled by microglia. Despite up to 40% of cortical neurons being partially enveloped at clinical stages, only a small percentage of envelopment proceeded to full engulfment. Partially enveloped neurons lacked apoptotic markers, but showed signs of functional decline. Neuronal envelopment was independent of the CD11b pathway, previously associated with phagocytosis of newborn neurons during neurodevelopment. This phenomenon of partial envelopment was consistently observed across multiple prion-affected brain regions, various mouse-adapted strains, and different subtypes of sporadic Creutzfeldt-Jakob disease (sCJD) in humans. The current work describes a phenomenon of partial envelopment of neurons by reactive microglia in the context of an actual neurodegenerative disease, not a disease model.
小胶质细胞被认为是中枢神经系统中负责吞噬作用的主要细胞。当前研究表明,在朊病毒疾病中,小胶质细胞在临床前期早期能有效吞噬朊病毒或朊蛋白(PrPSc)。然而,在临床前期后期,小胶质细胞的活性发生了关键转变,从摄取PrPSc转变为建立广泛的神经元 - 小胶质细胞体对体细胞接触。这种变化之后,PrPSc在大脑中迅速积累。包裹神经元的小胶质细胞表现出肥大的、组织蛋白酶D阳性的溶酶体区室。然而,大多数被包裹的神经元仅被小胶质细胞部分环绕。尽管在临床阶段高达40%的皮质神经元被部分包裹,但只有一小部分包裹过程会发展为完全吞噬。部分被包裹的神经元缺乏凋亡标记,但显示出功能衰退的迹象。神经元包裹独立于CD11b途径,该途径先前与神经发育过程中新生神经元的吞噬作用有关。在多个受朊病毒影响的脑区、各种小鼠适应株以及人类散发性克雅氏病(sCJD)的不同亚型中,均一致观察到这种部分包裹现象。当前的研究描述了在实际的神经退行性疾病而非疾病模型的背景下,反应性小胶质细胞对神经元进行部分包裹的现象。
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