Impaired brain insulin signalling in Parkinson's disease.

AIMS: Brain insulin resistance (i.e., decreased insulin/insulin-like growth factor-1 [IGF-1] signalling) may play a role in the pathophysiology of Parkinson's disease (PD), and several anti-diabetic drugs have entred clinical development to evaluate their potential disease-modifying properties in PD. A measure of insulin resistance is the amount of the downstream messenger insulin receptor substrate-1 that is phosphorylated at serine residues 312 (IRS-1pS312) or 616 (IRS-1pS616). We assessed IRS-1pS312 and IRS-1pS616 expression in post-mortem brain tissue of PD patients and a preclinical rat model based on viral-mediated expression of A53T mutated human α-synuclein (AAV2/9-h-α-synA53T). METHODS: IRS-1pS312 and IRS-1pS616 staining intensity were determined by immunofluorescence in both neurons and glial cells in the substantia nigra pars compacta (SNc) and putamen of PD patients and controls without known brain disease. We further explored a possible relation between α-synuclein aggregates and brain insulin resistance in PD patients. Both insulin resistance markers were also measured in the SNc and striatum of AAV2/9-h-α-synA53T rats. RESULTS: We found higher IRS-1pS312 staining intensity in nigral dopaminergic neurons and a trend for higher IRS-1pS312 staining intensity in putaminal neurons of PD patients. We observed no differences for IRS-1pS616 staining intensity in neurons or IRS-1pS312 staining intensity in glial cells. IRS-1pS312 showed high co-localisation within the core of nigral Lewy bodies. Like PD patients, AAV2/9-h-α-synA53T rats showed higher IRS-1pS312 staining intensity in the SNc and striatum than controls, whereas IRS-1pS616 was not different between groups. CONCLUSIONS: Our results provide evidence for brain insulin resistance in PD and support the rationale for repurposing anti-diabetic drugs for PD treatment.

L-DOPA regulates α-synuclein accumulation in experimental parkinsonism.

AIMS: Widespread accumulation of misfolded α-synuclein aggregates is a key feature of Parkinson's disease (PD). Although the pattern and extent of α-synuclein accumulation through PD brains is known, the impact of chronic dopamine-replacement therapy (the gold-standard pharmacological treatment of PD) on the fate of α-synuclein is still unknown. Here, we investigated the distribution and accumulation of α-synuclein in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) non-human primate model of PD and determined the effect of chronic L-DOPA treatment on MPTP-induced α-synuclein pathology. METHODS: We measured the density of α-synuclein and tau immuno-positive neurons in the substantia nigra, putamen, hippocampal CA1 region, temporal cortex and dentate nucleus of control, MPTP and MPTP+L-DOPA-treated monkeys. Moreover, we also extracted and quantified Triton-X (TX) soluble and insoluble α-synuclein in putamen and hippocampus samples from a separate cohort of control, MPTP and MPTP+L-DOPA-treated monkeys. RESULTS: MPTP-induced α-synuclein accumulation in NHP model of PD was not limited to the substantia nigra but also occurred in the putamen, hippocampal CA1 region and temporal cortex. Tau was increased only in the temporal cortex. Moreover, increased intraneuronal TX insoluble α-synuclein was truncated, but not in the structural form of Lewy bodies. The MPTP-induced increase in α-synuclein levels was abolished in animals having received L-DOPA in all the brain regions, except in the substantia nigra. CONCLUSIONS: Dopamine replacement therapy can dramatically ameliorate α-synuclein pathology in the MPTP NHP model of PD. Therefore, patient's dopaminergic medication should be systematically considered when assessing α-synuclein as a biomarker for diagnosis, monitoring disease progression and response to disease-modifying treatments.

Reduced oligodendrocyte exosome secretion in multiple system atrophy involves SNARE dysfunction.

Transportation of key proteins via extracellular vesicles has been recently implicated in various neurodegenerative disorders, including Parkinson's disease, as a new mechanism of disease spreading and a new source of biomarkers. Extracellular vesicles likely to be derived from the brain can be isolated from peripheral blood and have been reported to contain higher levels of α-synuclein (α-syn) in Parkinson's disease patients. However, very little is known about extracellular vesicles in multiple system atrophy, a disease that, like Parkinson's disease, involves pathological α-syn aggregation, though the process is centred around oligodendrocytes in multiple system atrophy. In this study, a novel immunocapture technology was developed to isolate blood CNPase-positive, oligodendrocyte-derived enriched microvesicles (OEMVs), followed by fluorescent nanoparticle tracking analysis and assessment of α-syn levels contained within the OEMVs. The results demonstrated that the concentrations of OEMVs were significantly lower in multiple system atrophy patients, compared to Parkinson's disease patients and healthy control subjects. It is also noted that the population of OEMVs involved was mainly in the size range closer to that of exosomes, and that the average α-syn concentrations (per vesicle) contained in these OEMVs were not significantly different among the three groups. The phenomenon of reduced OEMVs was again observed in a transgenic mouse model of multiple system atrophy and in primary oligodendrocyte cultures, and the mechanism involved was likely related, at least in part, to an α-syn-mediated interference in the interaction between syntaxin 4 and VAMP2, leading to the dysfunction of the SNARE complex. These results suggest that reduced OEMVs could be an important mechanism related to pathological α-syn aggregation in oligodendrocytes, and the OEMVs found in peripheral blood could be further explored for their potential as multiple system atrophy biomarkers.

Nilotinib Fails to Prevent Synucleinopathy and Cell Loss in a Mouse Model of Multiple System Atrophy.

BACKGROUND: Multiple system atrophy (MSA) is a rare, untreatable neurodegenerative disorder characterized by accumulation of α-synuclein in oligodendroglial inclusions. As such, MSA is a synucleinopathy along with Parkinson's disease (PD) and dementia with Lewy bodies. Activation of the abelson tyrosine kinase c-Abl leads to phosphorylation of α-synuclein at tyrosine 39, thereby promoting its aggregation and subsequent neurodegeneration. The c-Abl inhibitor nilotinib used for the treatment of chronic myeloid leukemia based on data collected in preclinical models of PD might interfere with pathogenic mechanisms that are relevant to PD and dementia with Lewy bodies, which motivated its assessment in an open-label clinical trial in PD and dementia with Lewy bodies patients. The objective of this study was to assess the preclinical efficacy of nilotinib in the specific context of MSA. METHODS: Mice expressing human wild-type α-synuclein in oligodendrocytes received daily injection of nilotinib (1 or 10 mg/kg) over 12 weeks. Postmortem analysis included the assessment of c-Abl activation, α-synuclein burden, and dopaminergic neurodegeneration. RESULTS: α-Synuclein phosphorylated at tyrosine 39 was detected in glial cytoplasmic inclusions in MSA patients. Increased activation of c-Abl and α-synuclein phosphorylation at tyrosine 39 were found in transgenic mice. Despite significant inhibition of c-Abl and associated reduction of α-synuclein phosphorylation at tyrosine 39 by 40%, nilotinib failed to reduce α-synuclein aggregate burden (including phosphorylation at serine 129) in the striatum and cortex or to lessen neurodegeneration in the substantia nigra. CONCLUSIONS: This preclinical study suggests that partial inhibition of c-Abl and reduction of α-synuclein phosphorylation at tyrosine 39 may not be a relevant target for MSA. © 2020 International Parkinson and Movement Disorder Society.

Deep brain stimulation does not enhance neuroinflammation in multiple system atrophy.

Slowly progressive, levodopa-responsive multiple system atrophy (MSA) may be misdiagnosed as Parkinson's disease (PD). Deep brain stimulation (DBS) is mostly ineffective in these patients and may even worsen the clinical course. Here we assessed whether neuropathological differences between patients with MSA who were treated with DBS of the subthalamic nucleus because of a misleading clinical presentation and typical disease cases may explain the more benign disease course of the former, and also the rapid clinical decline after surgery. The post-mortem assessment included the subthalamic nucleus, the globus pallidus, the thalamus and the putamen in five patients with MSA who received DBS and nine typical disease cases. There was no evidence for distinct neuroinflammatory profiles between both groups that could be related to the surgical procedure or that could explain the rapid clinical progression during DBS. Patients who received deep brain stimulation displayed a higher proportion of α-synuclein bearing neuronal cytoplasmic inclusions in the putamen compared with typical cases, while the number of surviving neurons was not different between groups. Our findings suggest that DBS does not induce neuroinflammatory changes in patients with MSA, at least several years after the surgery. We further hypothesize that the peculiar pattern of α-synuclein pathology may contribute to differences in the clinical phenotype, with a greater proportion of neuronal inclusions in the putamen being associated to a milder, "PD-like" phenotype with sustained levodopa response and slower disease progression.

Insulin resistance and exendin-4 treatment for multiple system atrophy.

See Stayte and Vissel (doi:10.1093/awx064) for a scientific commentary on this article. Multiple system atrophy is a fatal sporadic adult-onset neurodegenerative disorder with no symptomatic or disease-modifying treatment available. The cytopathological hallmark of multiple system atrophy is the accumulation of α-synuclein aggregates in oligodendrocytes, forming glial cytoplasmic inclusions. Impaired insulin/insulin-like growth factor-1 signalling (IGF-1) and insulin resistance (i.e. decreased insulin/IGF-1) have been reported in other neurodegenerative disorders such as Alzheimer's disease. Increasing evidence also suggests impaired insulin/IGF-1 signalling in multiple system atrophy, as corroborated by increased insulin and IGF-1 plasma concentrations in multiple system atrophy patients and reduced IGF-1 brain levels in a transgenic mouse model of multiple system atrophy. We here tested the hypothesis that multiple system atrophy is associated with brain insulin resistance and showed increased expression of the key downstream messenger insulin receptor substrate-1 phosphorylated at serine residue 312 in neurons and oligodendrocytes in the putamen of patients with multiple system atrophy. Furthermore, the expression of insulin receptor substrate 1 (IRS-1) phosphorylated at serine residue 312 was more apparent in inclusion bearing oligodendrocytes in the putamen. By contrast, it was not different between both groups in the temporal cortex, a less vulnerable structure compared to the putamen. These findings suggest that insulin resistance may occur in multiple system atrophy in regions where the neurodegenerative process is most severe and point to a possible relation between α-synuclein aggregates and insulin resistance. We also observed insulin resistance in the striatum of transgenic multiple system atrophy mice and further demonstrate that the glucagon-like peptide-1 analogue exendin-4, a well-tolerated and Federal Drug Agency-approved antidiabetic drug, has positive effects on insulin resistance and monomeric α-synuclein load in the striatum, as well as survival of nigral dopamine neurons. Additionally, plasma levels of exosomal neural-derived IRS-1 phosphorylated at serine residue 307 (corresponding to serine residue 312 in humans) negatively correlated with survival of nigral dopamine neurons in multiple system atrophy mice treated with exendin-4. This finding suggests the potential for developing this peripheral biomarker candidate as an objective outcome measure of target engagement for clinical trials with glucagon-like peptide-1 analogues in multiple system atrophy. In conclusion, our observation of brain insulin resistance in multiple system atrophy patients and transgenic mice together with the beneficial effects of the glucagon-like peptide-1 agonist exendin-4 in transgenic mice paves the way for translating this innovative treatment into a clinical trial.

Region-Specific Alterations of Matrix Metalloproteinase Activity in Multiple System Atrophy.

BACKGROUND: MSA is a sporadic progressive neurodegenerative disorder characterized by a variable combination of parkinsonism, cerebellar ataxia, and autonomic dysfunction. The pathological hallmark of MSA is the accumulation of alpha-synuclein aggregates in the cytoplasm of oligodendrocytes along with neuronal loss and neuroinflammation, as well as blood-brain barrier dysfunction and myelin deterioration. Matrix metalloproteinases are zinc-dependent endopeptidases involved in the remodeling of the extracellular matrix, demyelination, and blood-brain barrier permeability. Several lines of evidence indicate a role for these enzymes in various pathological processes, including stroke, multiple sclerosis, Parkinson's, and Alzheimer's disease. METHODS: This study aimed to assess potential alterations of matrix metalloproteinase-1, -2, -3, and -9 expression or activity in MSA postmortem brain tissue. RESULTS: Gelatin zymography revealed increased matrix metalloproteinase-2 activity in the putamen, but not in the frontal cortex, of MSA patients relative to controls. Immunohistochemistry revealed increased number of glial cells positive for matrix metalloproteinase-1, -2, and -3 in the putamen and frontal cortex of MSA patients. Double immunofluorescence revealed that matrix metalloproteinase-2 and -3 were expressed in astrocytes and microglia. Only matrix metalloproteinase-2 colocalized with alpha-synuclein in oligodendroglial cytoplasmic inclusions. CONCLUSION: These results demonstrate widespread alterations of matrix metalloproteinase expression in MSA and a pattern of increased matrix metalloproteinase-2 expression and activity affecting preferentially a brain region severely affected (putamen) over a relatively spared region (frontal cortex). Elevated matrix metalloproteinase expression may thus contribute to the disease process in MSA by promoting blood-brain barrier dysfunction and/or myelin degradation.

Loss of P-type ATPase ATP13A2/PARK9 function induces general lysosomal deficiency and leads to Parkinson disease neurodegeneration.

Parkinson disease (PD) is a progressive neurodegenerative disorder pathologically characterized by the loss of dopaminergic neurons from the substantia nigra pars compacta and the presence, in affected brain regions, of protein inclusions named Lewy bodies (LBs). The ATP13A2 gene (locus PARK9) encodes the protein ATP13A2, a lysosomal type 5 P-type ATPase that is linked to autosomal recessive familial parkinsonism. The physiological function of ATP13A2, and hence its role in PD, remains to be elucidated. Here, we show that PD-linked mutations in ATP13A2 lead to several lysosomal alterations in ATP13A2 PD patient-derived fibroblasts, including impaired lysosomal acidification, decreased proteolytic processing of lysosomal enzymes, reduced degradation of lysosomal substrates, and diminished lysosomal-mediated clearance of autophagosomes. Similar alterations are observed in stable ATP13A2-knockdown dopaminergic cell lines, which are associated with cell death. Restoration of ATP13A2 levels in ATP13A2-mutant/depleted cells restores lysosomal function and attenuates cell death. Relevant to PD, ATP13A2 levels are decreased in dopaminergic nigral neurons from patients with PD, in which ATP13A2 mostly accumulates within Lewy bodies. Our results unravel an instrumental role of ATP13A2 deficiency on lysosomal function and cell viability and demonstrate the feasibility and therapeutic potential of modulating ATP13A2 levels in the context of PD.

Intra-axonal protein aggregation in the peripheral nervous system.

Intracellular protein aggregates are common pathological hallmarks of many neurodegenerative disorders, and a defect in axonal transport is also incriminated. Here, we studied intra-axonal abnormal protein aggregation and axonopathy by using immunohistochemistry and electron microscopy on peripheral nerve biopsies from 12 patients with chronic axonal peripheral neuropathy (PN) of unknown etiology. Among these patients, three had idiopathic Parkinson's disease (PD). Intra-axonal ubiquitin aggregates were more numerous in the patients with PD. Intra-axonal aggregates of tau AT8 were found in five patients without PD. Phosphorylated α-synuclein aggregation was absent in all cases, while intra-axonal colocalization of 14-3-3 ß and ubiquitin was observed in two PD cases. Electron microscopy revealed enlarged axons crowded with organelles in six cases, including the three patients with PD, thus attesting a slowing of the axoplasmic flux. The number of ubiquitin aggregates was correlated with features of reduced axonal flux, while no such correlation was found for tau and 14-3-3 ß. Age did not correlate with the number of tau, ubiquitin, and 14-3-3 aggregates. Thus, both ubiquitin and/or abnormal tau intra-axonal aggregates may be found in chronic axonal PN. Ubiquitin aggregates might reduce the axonal flux or result from a disease producing slowing of axonal transport.

Endogenous morphine-like compound immunoreactivity increases in parkinsonism.

Morphine is endogenously synthesized in the central nervous system and endogenous dopamine is thought to be necessary for endogenous morphine formation. As Parkinson's disease results from the loss of dopamine and is associated with central pain, we considered how endogenous morphine is regulated in the untreated and l-DOPA-treated parkinsonian brain. However, as the cellular origin and overall distribution of endogenous morphine remains obscure in the pathological adult brain, we first characterized the distribution of endogenous morphine-like compound immunoreactive cells in the rat striatum. We then studied changes in the endogenous morphine-like compound immunoreactivity of medium spiny neurons in normal, Parkinson's disease-like and l-DOPA-treated Parkinson's disease-like conditions in experimental (rat and monkey) and human Parkinson's disease. Our results reveal an unexpected dramatic upregulation of neuronal endogenous morphine-like compound immunoreactivity and levels in experimental and human Parkinson's disease, only partially normalized by l-DOPA treatment. Our data suggest that endogenous morphine formation is more complex than originally proposed and that the parkinsonian brain experiences a dramatic upregulation of endogenous morphine immunoreactivity. The functional consequences of such endogenous morphine upregulation are as yet unknown, but based upon the current knowledge of morphine signalling, we hypothesize that it is involved in fatigue, depression and pain symptoms experienced by patients with Parkinson's disease.

Altered M1/M2 activation patterns of monocytes in severe relapsing experimental rat model of multiple sclerosis. Amelioration of clinical status by M2 activated monocyte administration.

OBJECTIVES: We investigated proinflammatory M1 and immunomodulatory M2 activation profiles of circulating monocytes in relapsing experimental autoimmune encephalomyelitis (EAE) model of multiple sclerosis, and tested whether altered M1/M2 equilibrium promotes CNS inflammation. RESULTS: Approaches of MRI macrophage tracking with USPIO nanoparticles and expression patterns of M1/M2 macrophages and microglia in brain and M1/M2 monocytes in blood samples at various disease stages revealed that M1/M2 equilibrium in blood and CNS favors mild EAE, while imbalance towards M1 promotes relapsing EAE. We consequently investigated whether M2 activated monocyte restoration in peripheral blood could cure acute clinical EAE disease. Administration of ex vivo activated M2 monocytes both suppressed ongoing severe EAE and increased immunomodulatory expression pattern in lesions, confirming their role in the induction of recovery. CONCLUSION: We conclude that imbalance of monocyte activation profiles and impaired M2 expression, are key factors in development of relapses. Our study opens new perspectives for therapeutic applications in MS.

Lack of limbic-predominant age-related TDP-43 encephalopathy (LATE) neuropathological changes in aged macaques with memory impairment.

The neuropathological changes of limbic-predominant age-related TDP-43 encephalopathy (LATE) are frequent in the aged population and are now recognized as a cause of memory impairment. However, it remains unknown if this proteinopathy is also present in other primate species. We thus investigated the presence and distribution of TDP-43 pathology in the hippocampus and amygdala of 7 aged memory-impaired rhesus macaques (Macaca mulatta, 18-32 years old) from 2 different cohorts. While present in an FTLD-TDP case used as a positive control for immunostaining, we found no TDP-43 or phosphorylated TDP-43 immunoreactive neuronal cytoplasmic inclusion in the amygdala or the hippocampus of these aged animals (as well as in young and mature macaques used as negative controls). We concluded that LATE is probably a human-specific condition, such as many other proteinopathies, and does not participate in age-related memory impairment in non-human primates.

The nigrostriatal pathway in Creutzfeldt-Jakob disease.

Parkinsonism, chorea, and dystonia are well-known clinical manifestations of Creutzfeldt-Jakob disease (CJD), but lesions of the nigrostriatal pathway have never been thoroughly studied. We performed a detailed neuropathologic study of the nigrostriatal pathway in 15 sporadic CJD and 2 variant CJD cases that included clinical correlations and assessment of neuron subtype loss, distribution of prion protein, alpha-synuclein, ubiquitin, and 14-3-3 aggregation. We found evidence of nigrostriatal pathway damage in these CJD cases. Dopaminergic neurons and striatal outflow neurons were markedly affected in sporadic CJD, whereas cholinergic interneurons were spared. In cases of CJD with chorea or myoclonus, there was less presynaptic dopaminergic loss than in cases of CJD with parkinsonism. The 2 variant CJD cases with parkinsonism or chorea showed severe cholinergic interneuron loss in the caudate and putamen, a pattern that differed from that found in sporadic CJD. alpha-Synuclein, ubiquitin, and 14-3-3 aggregation coexisted with prion protein aggregation, thereby generating mixed pathological features. These findings suggest a possible pathophysiological overlap of abnormal protein aggregation in CJD and Parkinson disease.

Systemic Gene Delivery by Single-Dose Intracardiac Administration of scAAV2/9 and scAAV2/rh10 Variants in Newborn Rats.

Recombinant adeno-associated virus serotype 9 (rAAV2/9) and pseudotype rhesus-10 (rAAV2/rh10) are used for gene delivery, especially into the central nervous system. Both serotypes cross the blood-brain barrier and mediate stable long-term transduction in dividing and nondividing cells. Among possible routes of administration, intracardiac injection holds the potential for widespread vector diffusion associated with a relatively simple approach. In this study adopting the intracardiac route, we compare the cell-specific tropism and transfection efficacy of a panel of engineered rAAV2/9 and rAAV2/rh10 vectors encoding the enhanced green fluorescent protein. We observed transduction in the brain and peripherally, with a predominant neuronal tropism while the various serotypes achieved different expression patterns.

Neuro-muscular biopsy in Churg-Strauss syndrome: 24 cases.

Churg-Strauss syndrome (CSS) is a distinctive clinical entity in which systemic vasculitis, associated with eosinophilia, occurs almost exclusively in individuals with adult-onset asthma. The major complications of the condition result from damage to the lungs, heart, and peripheral nerves. Necrotizing vasculitis with eosinophils in the cellular infiltrate, vascular or perivascular infiltration by eosinophils in absence of vessel wall necrosis, extra-vascular eosinophil infiltrates, and vascular or extra-vascular granuloma are histopathological features supportive of CSS. As the peripheral nerve disease often dominates the clinical picture, the peripheral nerve biopsy may be decisive in establishing the diagnosis. In this retrospective study of neuro-muscular biopsies in 24 CSS cases, the authors give an extensive description of neuropathological lesions associated with this disorder. Fifteen patients (62.5%) exhibited eosinophils either in extra-vascular infiltrates or in vessel walls, and 6 of them (25%) had an associated necrotizing vasculitis. Granulomas were found in only 3 cases (12.5%). The clinical diagnosis of CSS was supported in 15 out of the 24 patients (62.5%), in the nerve in 2 cases (8.3%), in the muscle in 8 cases (33.3%), and in both nerve and muscle in 5 others (20.8%).

Astrocytosis in parkinsonism: considering tripartite striatal synapses in physiopathology?

The current concept of basal ganglia organization and function in physiological and pathophysiological conditions excludes the most numerous cells in the brain, i.e., the astrocytes, present with a ratio of 10:1 neuron. Their role in neurodegenerative condition such as Parkinson's disease (PD) remains to be elucidated. Before embarking into physiological investigations of the yet-to-be-identified "tripartite" synapses in the basal ganglia in general and the striatum in particular, we therefore characterized anatomically the PD-related modifications in astrocytic morphology, the changes in astrocytic network connections and the consequences on the spatial relationship between astrocytic processes and asymmetric synapses in normal and PD-like conditions in experimental and human PD. Our results unravel a dramatic regulation of striatal astrocytosis supporting the hypothesis of a key role in (dys) regulating corticostriatal transmission. Astrocytes and their various properties might thus represent a therapeutic target in PD.

Age-dependent α-synuclein aggregation in the Microcebus murinus lemur primate.

Since age-dependent deposition of Aß-amyloid has been reported in the Microcebusmurinus, we posited that this animal could as well be a model of age-related synucleinopathy. We characterized the distribution of Aß-amyloid, α-synuclein and two of its modified forms in the brain of Microcebusmurinus aged from 1.5 to 10 years. Intracytoplasmic α-synuclein aggregates were observed only in aged animals in different brain regions, which were also phospho-Ser129 and nitrated α-synuclein immunoreactive. Age-dependent α-synuclein aggregation occurs spontaneously in mouse lemur primates. Microcebus murinus may provide a model to study age-associated α-synucleinopathy and for testing putative therapeutic interventions for both Alzheimer's and Parkinson's diseases.

Protein aggregation in the aging retina.

The age-related altered expression of neuron-related proteins as seen in other regions of the central nervous system is expected in the aging retina. Using immunohistochemical techniques, we characterized the distribution and aggregation of tau, ßA4-amyloid, α-synuclein, and ubiquitin in human retina obtained from 19 enucleated eyes of patients aged 49 to 87 years and correlated the findings with the ages. Using a phosphorylation-independent antibody, tau aggregates were observed within the cytoplasm of several photoreceptor cells, and there was a positive correlation between age and the number of tau-positive ganglionic cells. Tau deposits were immunonegative with a phosphorylation-dependent antibody. We did not observe ßA4-amyloid in subretinal pigment epithelium deposits or in neuroepithelial layers. α-Synuclein and ubiquitin inclusions were found in the inner nuclear layer, and there was colocalization of these proteins. The proportion of patients displaying such α-synuclein and/or ubiquitin intracytoplasmic inclusions was significantly higher with aging. The presence of ubiquitin deposits within drusen was remarkable, but diffuse ubiquitin aggregates between the retinal pigment epithelium and Bruch membrane were also noticed. These results indicate that protein aggregation in the retina increases with aging and that tau, α-synuclein, and ubiquitin should be the subjects of future investigations.