LRRK2 kinase inhibition reverses G2019S mutation-dependent effects on tau pathology progression

BACKGROUND

Mutations in leucine-rich repeat kinase 2 (LRRK2) are the most common cause of familial Parkinson's disease (PD). These mutations elevate the LRRK2 kinase activity, making LRRK2 kinase inhibitors an attractive therapeutic. LRRK2 kinase activity has been consistently linked to specific cell signaling pathways, mostly related to organelle trafficking and homeostasis, but its relationship to PD pathogenesis has been more difficult to define. LRRK2-PD patients consistently present with loss of dopaminergic neurons in the substantia nigra but show variable development of Lewy body or tau tangle pathology. Animal models carrying LRRK2 mutations do not develop robust PD-related phenotypes spontaneously, hampering the assessment of the efficacy of LRRK2 inhibitors against disease processes. We hypothesized that mutations in LRRK2 may not be directly related to a single disease pathway, but instead may elevate the susceptibility to multiple disease processes, depending on the disease trigger. To test this hypothesis, we have previously evaluated progression of α-synuclein and tau pathologies following injection of proteopathic seeds. We demonstrated that transgenic mice overexpressing mutant LRRK2 show alterations in the brain-wide progression of pathology, especially at older ages.

METHODS

Here, we assess tau pathology progression in relation to long-term LRRK2 kinase inhibition. Wild-type or LRRK2G2019S knock-in mice were injected with tau fibrils and treated with control diet or diet containing LRRK2 kinase inhibitor MLi-2 targeting the IC50 or IC90 of LRRK2 for 3-6 months. Mice were evaluated for tau pathology by brain-wide quantitative pathology in 844 brain regions and subsequent linear diffusion modeling of progression.

RESULTS

Consistent with our previous work, we found systemic alterations in the progression of tau pathology in LRRK2G2019S mice, which were most pronounced at 6 months. Importantly, LRRK2 kinase inhibition reversed these effects in LRRK2G2019S mice, but had minimal effect in wild-type mice, suggesting that LRRK2 kinase inhibition is likely to reverse specific disease processes in G2019S mutation carriers. Additional work may be necessary to determine the potential effect in non-carriers.

CONCLUSIONS

This work supports a protective role of LRRK2 kinase inhibition in G2019S carriers and provides a rational workflow for systematic evaluation of brain-wide phenotypes in therapeutic development.

Mitochondrial Inherited Disorders and their Correlation with Neurodegenerative Diseases

Mitochondria are essential organelles for the survival of a cell because they produce energy. The cells that need more mitochondria are neurons because they perform a variety of tasks that are necessary to support brain homeostasis. The build-up of abnormal proteins in neurons, as well as their interactions with mitochondrial proteins, or MAM proteins, cause serious health issues. As a result, mitochondrial functions, such as mitophagy, are impaired, resulting in the disorders described in this review. They are also due to mtDNA mutations, which alter the heritability of diseases. The topic of disease prevention, as well as the diagnosis, requires further explanation and exploration. Finally, there are treatments that are quite promising, but more detailed research is needed.

Influence of Protonation on the Norepinephrine Inhibiting α-Synuclein 71-82 Oligomerization

The pathogenesis of Parkinson's disease (PD) is closely linked to the massive presence of Lewy vesicles and Lewy axons in the cytoplasm of neurons, mainly consisting of α-synuclein (αS). Norepinephrine (NE), whose secretion can be increased by exercise, has been demonstrated to prevent the fibrillation of αS and to break down the mature αS fibrils. In this work, we focus on the influence of protonation on the inhibitory ability of NE by using amyloid core fragment αS71-82 as a template. All-atom replica-exchange molecular dynamics simulations (accumulating to 33.6 μs) in explicit water were performed to explore the inhibitory effect of protonated and nonprotonated NE on αS oligomerization. Our results show that NE/NE+ can lead to a significant decrease in β-sheet content with increasing temperature, while isolated αS maintains relatively higher β-sheet conformations until 363 K, implying that both NE and NE+ can lower the critical temperature required for αS fibril decomposition. NE and NE+ also lead to the formation of less compact αS oligomers by preventing the backbone hydrogen bonds and the side-chain packing. The protonation would affect the binding affinity, interaction modes, and binding intensity of NE with αS. Interesting, NE and NE+ have a distinct binding free energy in the electrostatic and solvation terms, which mostly counter each other and produce a weak binding intensity with αS. Our work contributes to a better understanding of the inhibitory mechanism of NE and NE+ on αS oligomerization relevant to PD pathogenesis, which may provide clues for the design of antiamyloid medicine.

Preclinical Research on Focused Ultrasound-Mediated Blood-Brain Barrier Opening for Neurological Disorders: A Review

Several therapeutic agents for neurological disorders are usually not delivered to the brain owing to the presence of the blood-brain barrier (BBB), a special structure present in the central nervous system (CNS). Focused ultrasound (FUS) combined with microbubbles can reversibly and temporarily open the BBB, enabling the application of various therapeutic agents in patients with neurological disorders. In the past 20 years, many preclinical studies on drug delivery through FUS-mediated BBB opening have been conducted, and the use of this method in clinical applications has recently gained popularity. As the clinical application of FUS-mediated BBB opening expands, it is crucial to understand the molecular and cellular effects of FUS-induced microenvironmental changes in the brain so that the efficacy of treatment can be ensured, and new treatment strategies established. This review describes the latest research trends in FUS-mediated BBB opening, including the biological effects and applications in representative neurological disorders, and suggests future directions.

Endogenous Levels of Alpha-Synuclein Modulate Seeding and Aggregation in Cultured Cells

Parkinson’s disease is a progressive neurodegenerative disorder characterized by the accumulation of misfolded alpha-synuclein in intraneuronal inclusions known as Lewy bodies and Lewy neurites. Multiple studies strongly implicate the levels of alpha-synuclein as a major risk factor for the onset and progression of Parkinson’s disease. Alpha-synuclein pathology spreads progressively throughout interconnected brain regions but the precise molecular mechanisms underlying the seeding of alpha-synuclein aggregation are still unclear. Here, using stable cell lines expressing alpha-synuclein, we examined the correlation between endogenous alpha-synuclein levels and the seeding propensity by exogenous alpha-synuclein preformed fibrils. We applied biochemical approaches and imaging methods in stable cell lines expressing alpha-synuclein and in primary neurons to determine the impact of alpha-synuclein levels on seeding and aggregation. Our results indicate that the levels of alpha-synuclein define the pattern and severity of aggregation and the extent of p-alpha-synuclein deposition, likely explaining the selective vulnerability of different cell types in synucleinopathies. The elucidation of the cellular processes involved in the pathological aggregation of alpha-synuclein will enable the identification of novel targets and the development of therapeutic strategies for Parkinson’s disease and other synucleinopathies.

Neuropathology and molecular diagnosis of Synucleinopathies

Synucleinopathies are clinically and pathologically heterogeneous disorders characterized by pathologic aggregates of α-synuclein in neurons and glia, in the form of Lewy bodies, Lewy neurites, neuronal cytoplasmic inclusions, and glial cytoplasmic inclusions. Synucleinopathies can be divided into two major disease entities: Lewy body disease and multiple system atrophy (MSA). Common clinical presentations of Lewy body disease are Parkinson's disease (PD), PD with dementia, and dementia with Lewy bodies (DLB), while MSA has two major clinical subtypes, MSA with predominant cerebellar ataxia and MSA with predominant parkinsonism. There are currently no disease-modifying therapies for the synucleinopathies, but information obtained from molecular genetics and models that explore mechanisms of α-synuclein conversion to pathologic oligomers and insoluble fibrils offer hope for eventual therapies. It remains unclear how α-synuclein can be associated with distinct cellular pathologies (e.g., Lewy bodies and glial cytoplasmic inclusions) and what factors determine neuroanatomical and cell type vulnerability. Accumulating evidence from in vitro and in vivo experiments suggests that α-synuclein species derived from Lewy body disease and MSA are distinct "strains" having different seeding properties. Recent advancements in in vitro seeding assays, such as real-time quaking-induced conversion (RT-QuIC) and protein misfolding cyclic amplification (PMCA), not only demonstrate distinct seeding activity in the synucleinopathies, but also offer exciting opportunities for molecular diagnosis using readily accessible peripheral tissue samples. Cryogenic electron microscopy (cryo-EM) structural studies of α-synuclein derived from recombinant or brain-derived filaments provide new insight into mechanisms of seeding in synucleinopathies. In this review, we describe clinical, genetic and neuropathologic features of synucleinopathies, including a discussion of the evolution of classification and staging of Lewy body disease. We also provide a brief discussion on proposed mechanisms of Lewy body formation, as well as evidence supporting the existence of distinct α-synuclein strains in Lewy body disease and MSA.

α-Synuclein-mediated neurodegeneration in Dementia with Lewy bodies: the pathobiology of a paradox

Dementia with Lewy bodies (DLB) is epitomized by the pathognomonic manifestation of α-synuclein-laden Lewy bodies within selectively vulnerable neurons in the brain. By virtue of prion-like inheritance, the α-synuclein protein inexorably undergoes extensive conformational metamorphoses and culminate in the form of fibrillar polymorphs, instigating calamitous damage to the brain's neuropsychological networks. This epiphenomenon is nebulous, however, by lingering uncertainty over the quasi "pathogenic" behavior of α-synuclein conformers in DLB pathobiology. Despite numerous attempts, a monolithic "α-synuclein" paradigm that is able to untangle the enigma enshrouding the clinicopathological spectrum of DLB has failed to emanate. In this article, we review conceptual frameworks of α-synuclein dependent cell-autonomous and non-autonomous mechanisms that are likely to facilitate the transneuronal spread of degeneration through the neuraxis. In particular, we describe how the progressive demise of susceptible neurons may evolve from cellular derangements perpetrated by α-synuclein misfolding and aggregation. Where pertinent, we show how these bona fide mechanisms may mutually accentuate α-synuclein-mediated neurodegeneration in the DLB brain.

Oxidative Stress, Mitochondrial Dysfunction, and Neuroprotection of Polyphenols with Respect to Resveratrol in Parkinson's Disease

Parkinson’s disease (PD) is the second most common neurodegenerative disease and is characterized by dopaminergic neuronal loss. The exact pathogenesis of PD is complex and not yet completely understood, but research has established the critical role mitochondrial dysfunction plays in the development of PD. As the main producer of cytosolic reactive oxygen species (ROS), mitochondria are particularly susceptible to oxidative stress once an imbalance between ROS generation and the organelle’s antioxidative system occurs. An overabundance of ROS in the mitochondria can lead to mitochondrial dysfunction and further vicious cycles. Once enough damage accumulates, the cell may undergo mitochondria-dependent apoptosis or necrosis, resulting in the neuronal loss of PD. Polyphenols are a group of natural compounds that have been shown to offer protection against various diseases, including PD. Among these, the plant-derived polyphenol, resveratrol, exhibits neuroprotective effects through its antioxidative capabilities and provides mitochondria protection. Resveratrol also modulates crucial genes involved in antioxidative enzymes regulation, mitochondrial dynamics, and cellular survival. Additionally, resveratrol offers neuroprotective effects by upregulating mitophagy through multiple pathways, including SIRT-1 and AMPK/ERK pathways. This compound may provide potential neuroprotective effects, and more clinical research is needed to establish the efficacy of resveratrol in clinical settings.

Neuroprotective Effects of Trehalose and Sodium Butyrate on Preformed Fibrillar Form of α-Synuclein-Induced Rat Model of Parkinson's Disease

Therapeutic options for Parkinson's disease (PD) are limited to a symptomatic approach, making it a global threat. Targeting aggregated alpha-synuclein (α-syn) clearance is a gold standard for ameliorating PD pathology, bringing autophagy into the limelight. Expression of autophagy related genes are under the regulation by histone modifications, however, its relevance in PD is yet to be established. Here, preformed fibrillar form (PFF) of α-syn was used to induce PD in wistar rats, which were thereafter subjected to treatment with trehalose (tre, 4g/kg, orally), a potent autophagy inducer and sodium butyrate (SB, 300 mg/kg, orally), a pan histone deacetylase inhibitor alone as well as in combination. The combination treatment significantly reduced motor deficits as evidenced after rotarod, narrow beam walk, and open field tests. Novel object location and recognition tests were performed to govern cognitive abnormality associated with advanced stage PD, which was overcome by the combination treatment. Additionally, with the combination, the level of pro-inflammatory cytokines were significantly reduced, along with elevated levels of dopamine and histone H3 acetylation. Further, mRNA analysis revealed that levels of certain autophagy related genes and proteins implicated in PD pathogenesis significantly improved after administration of both tre and SB. Immunofluorescence and H&E staining in the substantia nigra region mirrored a potential improvement after treatment with both tre and SB. Therefore, outcomes of the present study were adequate to prove that combinatorial efficacy with tre and SB may prove to be a formidable insight into ameliorating PD exacerbated by PFF α-syn as compared to its individual efficacy.

Interaction between Parkin and α-Synuclein in PARK2-Mediated Parkinson's Disease

Parkin and α-synuclein are two key proteins involved in the pathophysiology of Parkinson's disease (PD). Neurotoxic alterations of α-synuclein that lead to the formation of toxic oligomers and fibrils contribute to PD through synaptic dysfunction, mitochondrial impairment, defective endoplasmic reticulum and Golgi function, and nuclear dysfunction. In half of the cases, the recessively inherited early-onset PD is caused by loss of function mutations in the PARK2 gene that encodes the E3-ubiquitin ligase, parkin. Parkin is involved in the clearance of misfolded and aggregated proteins by the ubiquitin-proteasome system and regulates mitophagy and mitochondrial biogenesis. PARK2-related PD is generally thought not to be associated with Lewy body formation although it is a neuropathological hallmark of PD. In this review article, we provide an overview of post-mortem neuropathological examinations of PARK2 patients and present the current knowledge of a functional interaction between parkin and α-synuclein in the regulation of protein aggregates including Lewy bodies. Furthermore, we describe prevailing hypotheses about the formation of intracellular micro-aggregates (synuclein inclusions) that might be more likely than Lewy bodies to occur in PARK2-related PD. This information may inform future studies aiming to unveil primary signaling processes involved in PD and related neurodegenerative disorders.

Aging and Neuroinflammatory Disorders: New Biomarkers and Therapeutic Targets

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Chronic neuroinflammation is a common feature of the pathogenic mechanisms involved in various neurodegenerative age-associated disorders, such as Alzheimer's disease, multiple sclerosis, Parkinson’s disease, and dementia.

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In particular, persistent low-grade inflammation may disrupt the brain endothelial barrier and cause a significant increase of pro-inflammatory cytokines and immune cells into the cerebral tissue that, in turn, leads to microglia dysfunction and loss of neuroprotective properties.

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Nowadays, growing evidence highlights a strong association between persistent peripheral inflammation, as well as metabolic alterations, and neurodegenerative disorder susceptibility. The identification of common pathways involved in the development of these diseases, which modulate the signalling and immune response, is an important goal of ongoing research.

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The aim of this review is to elucidate which inflammation-related molecules are robustly associated with the risk of neurodegenerative diseases. Of note, peripheral biomarkers may represent direct measures of pathophysiologic processes common of aging and neuroinflammatory processes. In addition, molecular changes associated with the neurodegenerative process might be present many decades before the disease onset. Therefore, the identification of a comprehensive markers panel, closely related to neuroinflammation, could be helpful for the early diagnosis, and the identification of therapeutic targets to counteract the underlying chronic inflammatory processes.

Spread of α-synuclein pathology through the brain connectome is modulated by selective vulnerability and predicted by network analysis

Studies of patients afflicted by neurodegenerative diseases suggest that misfolded proteins spread through the brain along anatomically-connected networks, prompting progressive decline. Recently, mouse models have recapitulated the cell-to-cell transmission of pathogenic proteins and neuron death observed in patients. However, factors regulating spread of pathogenic proteins remain a matter of debate due to an incomplete understanding of how vulnerability functions in the context of spread. Here, we use quantitative pathology mapping in the mouse brain combined with network modeling to understand the spatiotemporal pattern of spread. α-Synuclein pathology patterns are well-described by a network model based on two factors—anatomical connectivity and endogenous α-Synuclein expression. The map and model allow assessment of selective vulnerability to α-Synuclein pathology development and neuron death. Finally, we use quantitative pathology to understand how the G2019S LRRK2 genetic risk factor impacts the spread and toxicity of α-Synuclein pathology.

α-Synuclein pathology in Parkinson's disease and related α-synucleinopathies

Over 20 years ago, the synaptic protein α-synuclein was identified as the primary component of the Lewy bodies (LBs) that are a sine qua non of Parkinson's disease (PD). Since that time, extensive research has demonstrated that α-synuclein pathology is not only a hallmark of PD, but can also cause neuronal dysfunction and death. Detailed staging of α-synuclein pathology in the brains of patients has revealed a progressive pattern of pathology that correlates with the symptoms of disease. Early in the disease course, PD patients exhibit motor dysfunction, and α-synuclein pathology at this stage is primarily found in regions controlling motor function. At later stages of disease as patients' cognitive function deteriorates, α-synuclein pathology can be found in cortical structures responsible for higher cognitive processing. The stereotypical progression of α-synuclein pathology through the brain over time suggests that there may be a physical transmission of pathological α-synuclein from one area of the brain to another. The transmission hypothesis posits that an initial seed of pathological α-synuclein in one neuron may be released and taken up by another vulnerable neuron and thereby initiate pathological misfolding of α-synuclein in the recipient neuron. In recent years, convergent evidence from various studies has indicated that pathological protein transmission can occur in the human brain. Cell and animal models based on the transmission hypothesis have shown not only that pathological α-synuclein can be transmitted from cell-to-cell, but that this pathology can lead to neuronal dysfunction and degeneration. The α-synuclein transmission hypothesis has profound implications for treatment of what is currently an intractable neurodegenerative disease. In this review, we explore the evidence for cell-to-cell transmission of pathological α-synuclein, the current understanding of how pathological α-synuclein can move to a new cell and template misfolding, and the therapeutic implications of α-synuclein transmission.

What is 'Alzheimer's Disease'? The 'Auguste D' Case Re-opened

What is Alzheimer's: an organic, neuropathological psychiatric disease, caused by plaques and tangles in aging brains or/and an existential condition affecting the minds of aging persons experiencing disconnection from meaning-bearing networks of social relations? Reviewing current research and revisiting Alzheimer's original case of 'Auguste D' this paper offers an historical-sociological genealogy that raises fundamental questions of causality, and even of the ontological status of Alzheimer's and the dementia reputed to it as a disease entity. Drawing on Kuhn's notion of 'science as usual' and Foucault's notion of the discursive formation of 'regimes of truth', our analysis seeks to understand how a sole medical focus on either bio-markers of neurological disease or genetic association was accomplished in the absence of sufficient and robust evidence. To counter the exclusion of psychosocial considerations, this paper offers two original hypotheses on the iconic case of 'Auguste D', taking into account the social milieu in which she lived and the specific circumstances of her life. It goes on to suggest the way in which the contemporary socio-cultural context may have dementiagenic tendencies. This research supports Gaines and Whitehouse's argument that research into the phenomenon and symptoms of Alzheimer's should focus on extracorporal and psychosocial factors.

200 Years of Parkinson's disease: what have we learnt from James Parkinson?

2017 marks 200 years since James Parkinson's published his 'Essay on the Shaking Palsy'. Although now most famous for describing the condition that came to bear his name, Parkinson had a wide range of interests and his influence spread beyond medicine. In this review, we provide a biography of James Parkinson's remarkable life.Parkinson's paper not only comprehensively described the symptoms of Parkinson's disease (PD), but challenged his peers to better understand the pathophysiology of the PD. Key observation over the next 2 centuries, included the recognition of the link between the substantia nigra and PD and the discoveries of dopamine deficiency in patients with PD. We review the subsequent development of pharmacological and surgical therapies. Despite great progress over the last 200 years, Parkinson's hopes for a 'cure if employed early enough' or that 'some remedial process may ere long be discovered by which at least the progression of the disease may be stopped' remain apposite today and we reflect on the challenges ahead for the next century.

How does parkinson's disease begin? Perspectives on neuroanatomical pathways, prions, and histology

Parkinson's disease (PD) is a multisystem disorder with involvement of the peripheral nervous system. Misfolding and aggregation of α-synuclein is central to the pathogenesis of PD, and it has been postulated that the disease may originate in olfactory and gastrointestinal nerve terminals. The prion-like behavior of α-synuclein has been convincingly demonstrated in vitro and in animal models of PD. Lewy-type pathology have been detected in peripheral organs many years prior to PD diagnosis, and 2 independent studies have now suggested that truncal vagotomy may be protective against the disorder. Other lines of evidence are difficult to reconcile with a peripheral onset of PD, most importantly the relative scarcity of post mortem cases with isolated gastrointestinal α-synuclein pathology without concomitant CNS pathology. This Scientific Perspectives article revisits some important topics with implications for the dual-hit hypothesis. An account of the neuroanatomical pathways necessary for stereotypical α-synuclein spreading is presented. Parallels to the existing knowledge on true prion disorders, including Creutzfeld-Jakob disease, are examined. Finally, the vagotomy studies and the somewhat inconsistent findings in the growing literature on peripheral α-synuclein pathology are discussed. It is concluded that the dual-hit hypothesis remains a potential explanation for PD pathogenesis, but several issues need to be resolved before more firm conclusions can be drawn. © 2017 International Parkinson and Movement Disorder Society.

Lewy and his inclusion bodies: Discovery and rejection

Fritz Jacob Heinrich Lewy described the pathology of Paralysis agitans [Parkinson disease] and was the first to identify eosinophilic inclusion bodies in neurons of certain brain nuclei, later known as Lewy bodies, the pathological signature of the Lewy body diseases. In 1912, he published his seminal study, followed soon after by an update paper, and 10 years later, in 1923, by his voluminous book, where he exhaustively described the subject. The publication provided extensive information on the pathology of Paralysis agitans, and the entirely novel finding of eosinophilic inclusion bodies, which would become widely recognized and debated in the future. His discovery was acknowledged by important researchers who even named the structure after him. However, after his last publication on the issue, inexplicably, he never mentioned his histopathological discovery again. Despite several hypotheses, the reasons that led him to neglect (reject) the structure which he so preeminently described have remained elusive.

Emigrated neuroscientists from Berlin to North America

The highest number of German scholars and physicians, forced by the National Socialist regime to emigrate for "race" or political reasons, were from Berlin. Language and medical exams were requested differently in their new host country-the United States-leading to a concentration of immigrants in the New York and Boston areas. Very early Emergency Committees in Aid of German Scholars and Physicians were established. Undergraduate students (like F. A. Freyhan, H. Lehmann, and H.-L. Teuber) from Berlin seemed to integrate easily, in contrast to colleagues of more advanced age. Some of the former chiefs and senior assistants of Berlin's neurological departments could achieve a successful resettlement (C. E. Benda, E. Haase, C. F. List, and F. Quadfasel) and some a minor degree of success (F. H. Lewy and K. Goldstein). A group of neuropsychiatrists from Bonhoeffer's staff at the Berlin Charité Hospital could rely on the forceful intercession of their former chief. The impact of the émigré colleagues on North American neuroscience is traced in some cases. Apart from the influential field of psychoanalysis, a more diffuse infiltration of German and European neuropsychiatry may be assumed. The contribution to the postwar blossoming of neuropsychology by the émigré neuroscientists K. Goldstein, F. Quadfasel, and H.-L. Teuber is demonstrated in this article.

Prevalence and risk factors of cognitive impairment in Parkinson disease: a population-based case-control study in Taiwan

The aim of this study was to evaluate the Parkinson disease (PD) prevalence of cognitive impairment in Taiwan.The case-control study consisted of 6177 cognitive impairment patients and 24,708 noncognitive impairment as controls for the period of 2006 to 2010 and both of the groups aged ≥50 years. The multivariable logistic regression analyses were used to estimate the odds ratio (OR) for cognitive impairment, and the 95% confidence intervals (CIs) among patients with PD were compared with those of non-PD patients.PD (adjusted odds ratio [aOR] is 3.07, 95% CI 2.76-3.41) is the one of the most contributed risk factors for cognitive impairment. Besides, we found a remarkable result of the diagnosed cognitive impairment of PD that was found highest in the first 6 months (aOR 11.98, 95% CI 8.51-16.86) and then decrease the incident year by year. The PD prevalence in a patient with cognitive impairment in our data present is 12.1% lower than those with truly dementia published previously and documented by western studies.We found a remarkable result of the diagnosed cognitive impairment of PD that was found highest in the first 6 months and then decrease the incident year by year.

Historical review of academic concepts of dementia in the world and Japan: with a short history of representative diseases

Expanding our knowledge of the history of dementia may be beneficial for its holistic understanding. This article aims to review the trajectory of the concepts of dementia in the world and Japan. Historical backgrounds of major dementia diseases are also addressed. The first reference to "imbecility" appeared in Greece in 6th century BC. A Japanese term "Mow-roku" (aged and devitalized) first appeared in 11th century, was replaced by "Chee-hou" (absent-minded imbecile) in 1960s, and then by "Ninchee-show" (cognitive impairment) in 2014 for humanistic reasons. In 1970s, dementia was delineated from normal aging, and the present concept of dementia was established.

Parkinson's disease-implicated kinases in the brain; insights into disease pathogenesis

Substantial evidence implicates abnormal protein kinase function in various aspects of Parkinson’s disease (PD) etiology. Elevated phosphorylation of the PD-defining pathological protein, α-synuclein, correlates with its aggregation and toxic accumulation in neurons, whilst genetic missense mutations in the kinases PTEN-induced putative kinase 1 and leucine-rich repeat kinase 2, increase susceptibility to PD. Experimental evidence also links kinases of the phosphoinositide 3-kinase and mitogen-activated protein kinase signaling pathways, amongst others, to PD. Understanding how the levels or activities of these enzymes or their substrates change in brain tissue in relation to pathological states can provide insight into disease pathogenesis. Moreover, understanding when and where kinase dysfunction occurs is important as modulation of some of these signaling pathways can potentially lead to PD therapeutics. This review will summarize what is currently known in regard to the expression of these PD-implicated kinases in pathological human postmortem brain tissue.

Alpha-synuclein and intracellular trafficking: impact on the spreading of Parkinson's disease pathology

Parkinson's disease is characterized by intracellular proteinaceous depositions known as Lewy bodies. These largely consist of the protein α-synuclein, whose physiological function remains unclear, but mutations and overexpression of the protein have been shown to cause early onset cases of Parkinson's disease. Deregulation of α-synuclein biology causes neurodegeneration and impaired neuronal trafficking, hinting at a possible contribution to the pathological mechanism. Recent studies produced some evidence hinting at the involvement of several regulators of the transport machinery such as Rab GTPases and SNARE proteins, but also shown that α-synuclein can be propagated between cells. Here, we discuss the molecular interplay of α-synuclein with the intracellular transport machinery, its consequences, and the implications for disease mechanisms.

Centenary of Lewy bodies (1912-2012)

During the years from 1908 until 1923, Lewy was the first to detail the pathological anatomy of Parkinson's disease, leading to his seminal contribution in 1912 describing the neuronal eosinophilic cytoplasmatic concentric inclusion bodies in the brainstem, later accomplished by more systematic investigations in 1923 (Lewy in Lewandowsky's Handbuch der Neurologie, 3. Band: Spez. Neurologie II. Springer, Berlin, pp 920-933, 1912). With the exception of a minority of cases and those that displayed postencephalitic Parkinsonism, Lewy was not able to confirm the significance of the substantia nigra. The findings of Tretiakoff in 1919 (significance of the substantia nigra in PD and coining of the term 'Corps de Lewy') have been underestimated or ignored for a long time. In a historical review on basal ganglia diseases from 1942, Lewy stressed the histological abnormalities of the basal ganglia and their diffuse distribution but not expressly the inclusion bodies, which in his former studies were unique in PD. For Lewy this finding was not a characteristic of the disease. Subsequent to his expulsion from Nazi-Germany in 1933, Lewy never resumed his research on PD. At the time of Lewy's death in 1950, the era of the Lewy bodies, Lewy-body-disease and the identification of atypical Parkinson syndrome cases had not even begun and followed much later.

Microglial activation and antioxidant responses induced by the Parkinson's disease protein α-synuclein

Parkinson’s disease (PD) is the second most common age-related neurodegenerative disorder typified by tremor, rigidity, akinesia and postural instability due in part to the loss of dopamine within the nigrostriatal system. The pathologic features of this disorder include the loss of substantia nigra dopamine neurons and attendant striatal terminals, the presence of large protein-rich neuronal inclusions containing fibrillar α-synuclein and increased numbers of activated microglia. Evidence suggests that both misfolded α-synuclein and oxidative stress play an important role in the pathogenesis of sporadic PD. Here we review evidence that α-synuclein activates glia inducing inflammation and that Nrf2-directed phase-II antioxidant enzymes play an important role in PD. We also provide new evidence that the expression of antioxidant enzymes regulated in part by Nrf2 is increased in a mouse model of α-synuclein overexpression. We show that misfolded α-synuclein directly activates microglia inducing the production and release of the proinflammatory cytokine, TNF-α, and increasing antioxidant enzyme expression. Importantly, we demonstrate that the precise structure of α-synuclein is important for induction of this proinflammatory pathway. This complex α-synuclein-directed glial response highlights the importance of protein misfolding, oxidative stress and inflammation in PD and represents a potential locus for the development of novel therapeutics focused on induction of the Nrf2-directed antioxidant pathway and inhibition of protein misfolding.

α-Synuclein as CSF and Blood Biomarker of Dementia with Lewy Bodies

Dementia with Lewy bodies (DLB) is a common subtype of dementia in the elderly. DLB is neuropathologically characterized by the presence of Lewy bodies and Lewy neurites, both of which are composed of α-synuclein. Although α-synuclein was initially considered to be an exclusively intracellular protein, it has been found to be secreted into biological fluids. α-Synuclein in biological fluids such as cerebrospinal fluid (CSF) and blood has been discussed as a potential biomarker of DLB and α-synuclein-related disorders, because α-synuclein is characteristically accumulated in the brain of patients with these disorders. The α-synuclein level in CSF has been examined by several investigators, and the majority of studies have shown a reduction in CSF α-synuclein level in DLB and α-synuclein-related disorders. Discrepant findings of studies of plasma α-synuclein level in patients with DLB have been reported. Because the level of α-synuclein stored in red blood cells is considerably high, blood contamination and haemolysis during sample collection and processing should be considered as a confounding factor for quantification of α-synuclein. Here, the recent progress in the studies of α-synuclein as a biomarker of DLB and their potential clinical applications are reviewed.

Parkinson's disease

Parkinson's disease (PD) is the most common age-related motoric neurodegenerative disease initially described in the 1800's by James Parkinson as the 'Shaking Palsy'. Loss of the neurotransmitter dopamine was recognized as underlying the pathophysiology of the motor dysfunction; subsequently discovery of dopamine replacement therapies brought substantial symptomatic benefit to PD patients. However, these therapies do not fully treat the clinical syndrome nor do they alter the natural history of this disorder motivating clinicians and researchers to further investigate the clinical phenotype, pathophysiology/pathobiology and etiology of this devastating disease. Although the exact cause of sporadic PD remains enigmatic studies of familial and rare toxicant forms of this disorder have laid the foundation for genome wide explorations and environmental studies. The combination of methodical clinical evaluation, systematic pathological studies and detailed genetic analyses have revealed that PD is a multifaceted disorder with a wide-range of clinical symptoms and pathology that include regions outside the dopamine system. One common thread in PD is the presence of intracytoplasmic inclusions that contain the protein, α-synuclein. The presence of toxic aggregated forms of α-synuclein (e.g., amyloid structures) are purported to be a harbinger of subsequent pathology. In fact, PD is both a cerebral amyloid disease and the most common synucleinopathy, that is, diseases that display accumulations of α-synuclein. Here we present our current understanding of PD etiology, pathology, clinical symptoms and therapeutic approaches with an emphasis on misfolded α-synuclein.

The Wilson films--Parkinson's disease

Short sequences in the Wilson film illustrate clinical aspects of bradykinesia and tremor in Parkinson's disease. What might have been the motivation of Wilson to capture these symptoms, and how would we view them today?