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Pérez-Acuña D, Rhee KH, Shin SJ, Ahn J, Lee JY, Lee SJ. Retina-to-brain spreading of α-synuclein after intravitreal injection of preformed fibrils. Acta Neuropathol Commun 2023; 11:83. [PMID: 37210559 DOI: 10.1186/s40478-023-01575-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 04/30/2023] [Indexed: 05/22/2023] Open
Abstract
Parkinson's disease (PD) is a neurodegenerative disorder characterized by the aggregation of misfolded α-synuclein and progressive spreading of the aggregates from a few discrete regions to wider brain regions. Although PD has been classically considered a movement disorder, a large body of clinical evidence has revealed the progressive occurrence of non-motor symptoms. Patients present visual symptoms in the initial stages of the disease, and accumulation of phospho-α-synuclein, dopaminergic neuronal loss, and retinal thinning has been observed in the retinas of PD patients. Based on such human data, we hypothesized that α-synuclein aggregation can initiate in the retina and spread to the brain through the visual pathway. Here, we demonstrate accumulation of α-synuclein in the retinas and brains of naive mice after intravitreal injection of α-synuclein preformed fibrils (PFFs). Histological analyses showed deposition of phospho-α-synuclein inclusions within the retina 2 months after injection, with increased oxidative stress leading to loss of retinal ganglion cells and dopaminergic dysfunction. In addition, we found accumulation of phospho-α-synuclein in cortical areas with accompanying neuroinflammation after 5 months. Collectively, our findings suggest that retinal synucleinopathy lesions initiated by intravitreal injection of α-synuclein PFFs spread to various brain regions through the visual pathway in mice.
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Affiliation(s)
- Dayana Pérez-Acuña
- Department of Biomedical Sciences, Seoul National University College of Medicine, 103 Daehak-Ro, Jongro-Gu, Seoul, 03080, Korea
| | - Ka Hyun Rhee
- Department of Biomedical Sciences, Seoul National University College of Medicine, 103 Daehak-Ro, Jongro-Gu, Seoul, 03080, Korea
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Soo Jean Shin
- Department of Biomedical Sciences, Seoul National University College of Medicine, 103 Daehak-Ro, Jongro-Gu, Seoul, 03080, Korea
| | - Jeeyun Ahn
- Department of Ophthalmology, College of Medicine, Seoul Metropolitan Government-Seoul National University Boramae Medical Center, Seoul National University, Seoul, South Korea
| | - Jee-Young Lee
- Department of Neurology, Seoul Metropolitan Government-Seoul National University Boramae Medical Center, Seoul National University College of Medicine, Seoul, South Korea
| | - Seung-Jae Lee
- Department of Biomedical Sciences, Seoul National University College of Medicine, 103 Daehak-Ro, Jongro-Gu, Seoul, 03080, Korea.
- Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, South Korea.
- Convergence Research Center for Dementia, Seoul National University College of Medicine, Seoul, South Korea.
- Neuramedy, Seoul, South Korea.
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Yang Q, Lin X, Xiao J, Zhong W, Wang F, Tan H, Rao B, Qu J, Zhang J. Expression of α‐Synuclein in the mouse retina is confined to inhibitory presynaptic elements. J Comp Neurol 2023; 531:1057-1079. [PMID: 37002599 DOI: 10.1002/cne.25481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 01/18/2023] [Accepted: 03/13/2023] [Indexed: 04/03/2023]
Abstract
α-Synuclein (α-Syn) is enriched in presynaptic terminals of the central nervous system including the retina and plays a role in the synaptic vesicle cycle and synaptic transmission. Abnormal aggregation of α-Syn is considered to be the main component of the Lewy bodies that are the pathological hallmarks of Parkinson's disease. Although expression pattern of α-Syn has been described in the retinas, its precise cellular and subcellular locations are poorly understood. We investigated the precise expression of α-Syn using light microscopy (LM) and electron microscopy (EM) with antibodies against α-Syn in the mouse retina. We found that the majority of α-Syn immunoreactivity (IR) is located in GABAergic, glycinergic, and dopaminergic amacrine cells, and their processes often make a direct synapse to other labeled or unlabeled amacrine profiles, bipolar cell terminals, or ganglion cell dendrites. Further, our LM and immuno-EM results confirm the absence of α-Syn in excitatory photoreceptors, bipolar cell bodies, and their ribbon synapses, providing evidence, for the first time, that ribbon synapses do not express α-Syn. Additionally, α-Syn IR is located in the ganglion cells, some of which are intrinsically photosensitive retinal ganglion cells. These results reveal a previously unappreciated inhibitory synapse-specific expression pattern of α-Syn in the retina, suggesting that α-Syn may play a distinct role in the modulation and integration of inhibitory synaptic transmission in the retina.
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Affiliation(s)
- Qingwen Yang
- Laboratory of Retinal Physiology and Disease School of Ophthalmology and Optometry and Eye Hospital Wenzhou Medical University Wenzhou China
| | - Xin Lin
- Laboratory of Retinal Physiology and Disease School of Ophthalmology and Optometry and Eye Hospital Wenzhou Medical University Wenzhou China
| | - Jiayi Xiao
- Laboratory of Retinal Physiology and Disease School of Ophthalmology and Optometry and Eye Hospital Wenzhou Medical University Wenzhou China
| | - Wenhui Zhong
- Laboratory of Retinal Physiology and Disease School of Ophthalmology and Optometry and Eye Hospital Wenzhou Medical University Wenzhou China
| | - Fenglan Wang
- Laboratory of Retinal Physiology and Disease School of Ophthalmology and Optometry and Eye Hospital Wenzhou Medical University Wenzhou China
| | - Hang Tan
- Laboratory of Retinal Physiology and Disease School of Ophthalmology and Optometry and Eye Hospital Wenzhou Medical University Wenzhou China
| | - Bilin Rao
- Laboratory of Retinal Physiology and Disease School of Ophthalmology and Optometry and Eye Hospital Wenzhou Medical University Wenzhou China
| | - Jia Qu
- State Key Laboratory of Ophthalmology Optometry and Vision Science, Eye Hospital, Wenzhou Medical University Wenzhou China
- National Clinical Research Center for Ocular Diseases Eye Hospital Wenzhou Medical University Wenzhou China
| | - Jun Zhang
- Laboratory of Retinal Physiology and Disease School of Ophthalmology and Optometry and Eye Hospital Wenzhou Medical University Wenzhou China
- State Key Laboratory of Ophthalmology Optometry and Vision Science, Eye Hospital, Wenzhou Medical University Wenzhou China
- National Clinical Research Center for Ocular Diseases Eye Hospital Wenzhou Medical University Wenzhou China
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Kilicarslan I, Zanetti L, Novelli E, Schwarzer C, Strettoi E, Koschak A. Knockout of Ca V1.3 L-type calcium channels in a mouse model of retinitis pigmentosa. Sci Rep 2021; 11:15146. [PMID: 34312410 PMCID: PMC8313562 DOI: 10.1038/s41598-021-94304-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 07/09/2021] [Indexed: 11/09/2022] Open
Abstract
Retinitis Pigmentosa is a genetically heterogeneous, degenerative retinal disorder characterized by gradual dysfunction and death of photoreceptors, first rods and later cones, and progressive blindness. Studies suggested that application of L-type calcium channel blockers rescues photoreceptors in paradigms related to Ca2+ overflow. To investigate whether Cav1.3 L-type channels have protective effects in the retina, we established a new mouse model by crossing rd10, modeling autosomal-recessive RP, with Cav1.3 deficient mice (rd10/Cav1.3KO). Our immunohistochemical analyses revealed an influence of Cav1.3 channels on the degenerative process of photoreceptors. The absence of Cav1.3 delayed the centre-to-periphery degeneration of rods indicated by a significantly higher number of photoreceptor rows and, consequently, of cones. In accordance with a preserved number of cones we observed a regular row of cone somas in rd10/Cav1.3-KO retinas. Surviving rod photoreceptors maintained synaptic contacts with rod bipolar cells. However, the delay in degeneration was only observed up to postnatal day 45. Although we observed a reduction in the spontaneous oscillatory retinal activity during multielectrode array analyses, measurable functional preservation was lacking in behavioural tests. In conclusion, Cav1.3 channels contribute to photoreceptor degeneration in rd10 retinas but photoreceptor temporary rescue might rather be achieved indirectly through other retinal cell layers.
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Affiliation(s)
- Irem Kilicarslan
- Institute of Pharmacy, Pharmacology and Toxicology, Center for Chemistry and Biomedicine, University of Innsbruck, Innrain 80-82, 6020, Innsbruck, Austria
| | - Lucia Zanetti
- Institute of Pharmacy, Pharmacology and Toxicology, Center for Chemistry and Biomedicine, University of Innsbruck, Innrain 80-82, 6020, Innsbruck, Austria
| | | | - Christoph Schwarzer
- Department of Pharmacology, Medical University of Innsbruck, 6020, Innsbruck, Austria
| | - Enrica Strettoi
- CNR Neuroscience Institute, 56124, Pisa, Italy. .,Istituto Di Neuroscienze CNR, Area della Ricerca, Via Giuseppe Moruzzi 1, 56100, Pisa, Italy.
| | - Alexandra Koschak
- Institute of Pharmacy, Pharmacology and Toxicology, Center for Chemistry and Biomedicine, University of Innsbruck, Innrain 80-82, 6020, Innsbruck, Austria.
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Choi S, Guo L, Cordeiro MF. Retinal and Brain Microglia in Multiple Sclerosis and Neurodegeneration. Cells 2021; 10:cells10061507. [PMID: 34203793 PMCID: PMC8232741 DOI: 10.3390/cells10061507] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Revised: 05/28/2021] [Accepted: 06/11/2021] [Indexed: 12/24/2022] Open
Abstract
Microglia are the resident immune cells of the central nervous system (CNS), including the retina. Similar to brain microglia, retinal microglia are responsible for retinal surveillance, rapidly responding to changes in the environment by altering morphotype and function. Microglia become activated in inflammatory responses in neurodegenerative diseases, including multiple sclerosis (MS). When activated by stress stimuli, retinal microglia change their morphology and activity, with either beneficial or harmful consequences. In this review, we describe characteristics of CNS microglia, including those in the retina, with a focus on their morphology, activation states and function in health, ageing, MS and other neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, glaucoma and retinitis pigmentosa, to highlight their activity in disease. We also discuss contradictory findings in the literature and the potential ways of reducing inconsistencies in future by using standardised methodology, e.g., automated algorithms, to enable a more comprehensive understanding of this exciting area of research.
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Affiliation(s)
- Soyoung Choi
- UCL Institute of Ophthalmology, London EC1V 9EL, UK; (S.C.); (L.G.)
| | - Li Guo
- UCL Institute of Ophthalmology, London EC1V 9EL, UK; (S.C.); (L.G.)
| | - Maria Francesca Cordeiro
- UCL Institute of Ophthalmology, London EC1V 9EL, UK; (S.C.); (L.G.)
- ICORG, Imperial College London, London NW1 5QH, UK
- Correspondence:
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Zanetti L, Kilicarslan I, Netzer M, Babai N, Seitter H, Koschak A. Function of cone and cone-related pathways in Ca V1.4 IT mice. Sci Rep 2021; 11:2732. [PMID: 33526839 DOI: 10.1038/s41598-021-82210-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 01/11/2021] [Indexed: 11/09/2022] Open
Abstract
CaV1.4 L-type calcium channels are predominantly expressed in photoreceptor terminals playing a crucial role for synaptic transmission and, consequently, for vision. Human mutations in the encoding gene are associated with congenital stationary night blindness type-2. Besides rod-driven scotopic vision also cone-driven photopic responses are severely affected in patients. The present study therefore examined functional and morphological changes in cones and cone-related pathways in mice carrying the CaV1.4 gain-of function mutation I756T (CaV1.4-IT) using multielectrode array, patch-clamp and immunohistochemical analyses. CaV1.4-IT ganglion cell responses to photopic stimuli were seen only in a small fraction of cells indicative of a major impairment in the cone pathway. Though cone photoreceptors underwent morphological rearrangements, they retained their ability to release glutamate. Our functional data suggested a postsynaptic cone bipolar cell defect, supported by the fact that the majority of cone bipolar cells showed sprouting, while horizontal cells maintained contacts with cones and cone-to-horizontal cell input was preserved. Furthermore a reduction of basal Ca2+ influx by a calcium channel blocker was not sufficient to rescue synaptic transmission deficits caused by the CaV1.4-IT mutation. Long term treatments with low-dose Ca2+ channel blockers might however be beneficial reducing Ca2+ toxicity without major effects on ganglion cells responses.
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