Progression of phosphorylated α-synuclein in Macaca fuscata.

Prion-like spreading of abnormal proteins is proposed to occur in neurodegenerative diseases, and the progression of α-synuclein (α-syn) deposits has been reported in the brains of animal models injected with synthetic α-syn fibrils or pathological α-syn prepared from patients with Parkinson's disease (PD) and dementia with Lewy bodies (DLB). However, α-syn transmission in nonhuman primates, which are more similar to humans, has not been fully clarified. Here, we injected synthetic human α-syn fibrils into the left striatum of a macaque monkey (Macaca fuscata). At 3 months after the injection, we examined neurodegeneration and α-syn pathology in the brain using α-syn epitope-specific antibodies, antiphosphorylated α-syn antibodies (pSyn#64 and pSer129), anti-ubiquitin antibodies, and anti-p62 antibodies. Immunohistochemical examination with pSyn#64, pSer129, and α-syn epitope-specific antibodies revealed Lewy bodies, massive α-syn-positive neuronal intracytoplasmic inclusions (NCIs), and neurites in the left putamen. These inclusions were also positive for ubiquitin and p62. LB509, a human-specific α-syn antibody targeting amino acid residues 115-122, showed limited immunoreactivity around the injection site. The left substantia nigra (SN) and the bilateral frontal cortex also contained some NCIs and neurites. The left hemisphere, including parietal/temporal cortex presented sparse α-syn pathology, and no immunoreactivity was seen in olfactory nerves, amygdala, hippocampus, or right parietal/temporal cortex. Neuronal loss and gliosis in regions with α-syn pathology were mild, except for the left striatum and SN. Our results indicate that abnormal α-syn fibrils propagate throughout the brain of M. fuscata via projection, association, and commissural fibers, though the progression of α-syn pathology is limited.

Kawakami I ，Motoda A ，Hashimoto M ，Shimozawa A ，Masuda-Suzukake M ，Ohtani R ，Takase M ，Kumashiro M ，Samejima K ，Hasegawa M ... -  《-》

Oligodendrocytes Prune Axons Containing α-Synuclein Aggregates In Vivo: Lewy Neurites as Precursors of Glial Cytoplasmic Inclusions in Multiple System Atrophy?

De Nuccio F ，Kashyrina M ，Serinelli F ，Laferrière F ，Lofrumento DD ，De Giorgi F ，Ichas F ... -  《Biomolecules》

Intrastriatal alpha-synuclein fibrils in monkeys: spreading, imaging and neuropathological changes.

Several studies have demonstrated that intrastriatal injections of fibrillar α-synuclein in rodent brain induced a Parkinson's disease-like propagation of Lewy body pathology with significant nigrostriatal neurodegeneration. This study evaluated the pathological features when exogenous α-synuclein preformed fibrils were injected into the putamen of non-human primates. Eight cynomolgus monkeys received unilateral intraputamen injections of α-synuclein preformed fibrils and four monkeys received sham surgery. Monkeys were assessed with 123I-PE2I single-photon emission computerized tomography scans targeting the dopamine transprter at baseline, 3, 6, 9, 12, and 15 months. Imaging revealed a robust increase in dopamine transporter binding, an effect confirmed by port-mortem immunohistochemical analyses, suggesting that upregulation of dopamine transporter occurs as part of an early pathological process. Histochemistry and immunohistochemistry revealed that α-synuclein preformed fibrils injections into the putamen induced intraneuronal inclusions positive for phosphorylated α-synuclein in ipsilateral substantia nigra and adjacent to the injection site. α-Synuclein inclusions were thioflavin-S-positive suggesting that the inclusions induced by α-synuclein preformed fibrils exhibited pathological properties similar to amyloid-like Lewy body pathology in Parkinson's disease brains. The α-synuclein preformed fibrils resulted in Lewy pathology in the ipsilateral substantia nigra with significant reduction (-29.30%) of dopaminergic neurons as compared with controls. Nigral neurons with α-synuclein inclusions exhibited a phenotypic downregulation of the dopamine markers tyrosine hydroxylase and Nurr1. Taken together, our findings demonstrate that α-synuclein preformed fibrils induce a synucleinopathy in non-human primates with authentic Lewy pathology and nigrostriatal changes indicative of early Parkinson's disease.

Chu Y ，Muller S ，Tavares A ，Barret O ，Alagille D ，Seibyl J ，Tamagnan G ，Marek K ，Luk KC ，Trojanowski JQ ，Lee VMY ，Kordower JH ... -  《-》

Synapsin III is a key component of α-synuclein fibrils in Lewy bodies of PD brains.

Longhena F ，Faustini G ，Varanita T ，Zaltieri M ，Porrini V ，Tessari I ，Poliani PL ，Missale C ，Borroni B ，Padovani A ，Bubacco L ，Pizzi M ，Spano P ，Bellucci A ... -  《-》

Propagation of pathological α-synuclein in marmoset brain.

Shimozawa A ，Ono M ，Takahara D ，Tarutani A ，Imura S ，Masuda-Suzukake M ，Higuchi M ，Yanai K ，Hisanaga SI ，Hasegawa M ... -  《Acta Neuropathologica Communications》