Influence of Drug-Carrier Polymers on Alpha-Synucleinopathies: A Neglected Aspect in New Therapies Development.

Current therapeutic strategies to treat neurodegenerative diseases, such as alpha-synucleinopathies, aim at enhancing the amount of drug reaching the brain. Methods proposed, such as intranasal administration, should be able to bypass the blood brain barrier (BBB) and even when directly intracerebrally injected they could require a carrier to enhance local release of drugs. We have investigated the effect of a model synthetic hydrogel to be used as drug carrier on the amount of alpha-synuclein aggregates in cells in culture. The results indicated that alpha-synuclein aggregation was affected by the synthetic polymer, suggesting the need for testing the effect of any used material on the pathological process before its application as drug carrier.

Alpha-synuclein in peripheral tissues and body fluids as a biomarker for Parkinson's disease - a systematic review.

Parkinson's disease (PD) is neuropathologically characterized as an alpha-synucleinopathy. Alpha-synuclein-containing inclusions are stained as Lewy bodies and Lewy neurites in the brain, which are the pathological hallmark of PD. However, alpha-synuclein-containing inclusions in PD are not restricted to the central nervous system, but are also found in peripheral tissues. Alpha-synuclein levels can also be measured in body fluids. The aim of this study was to conduct a systematic review of available evidence to determine the utility of alpha-synuclein as a peripheral biomarker of PD. We searched PubMed (1948 to 26 May 2013), Embase (1974 to 26 May 2013), the Cochrane Library (up to 26 May 2013), LILACS (up to 26 May 2013) and CINAHL (up to 26 May 2013) for the studies of alpha-synuclein in peripheral tissues or body fluids in PD. A total of 49 studies fulfilled the search criteria. Peripheral tissues such as colonic mucosa showed a sensitivity of 42-90% and a specificity of 100%; submandibular salivary glands showed sensitivity and specificity of 100%; skin biopsy showed 19% sensitivity and 80% specificity in detecting alpha-synuclein pathology. CSF alpha-synuclein had 71-94% sensitivity and 25-53% specificity for distinguishing PD from controls. Plasma alpha-synuclein had 48-53% sensitivity and 69-85% specificity. Neither plasma nor CSF alpha-synuclein is presently a reliable marker of PD. This differs from alpha-synuclein in solid tissue samples of the enteric and autonomic nervous system, which offer some potential as a surrogate marker of brain synucleinopathy.

Worldwide distribution of PSEN1 Met146Leu mutation: a large variability for a founder mutation.

OBJECTIVE: Large kindreds segregating familial Alzheimer disease (FAD) offer the opportunity of studying clinical variability as observed for presenilin 1 (PSEN1) mutations. Two early-onset FAD (EOFAD) Calabrian families with PSEN1 Met146Leu (ATG/CTG) mutation constitute a unique population descending from a remote common ancestor. Recently, several other EOFAD families with the same mutation have been described worldwide. METHODS: We searched for a common founder of the PSEN1 Met146Leu mutation in families with different geographic origins by genealogic and molecular analyses. We also investigated the phenotypic variability at onset in a group of 50 patients (mean age at onset 40.0 +/- 4.8 years) by clinical, neuropsychological, and molecular methodologies. RESULTS: EOFAD Met146Leu families from around the world resulted to be related and constitute a single kindred originating from Southern Italy before the 17th century. Phenotypic variability at onset is broad: 4 different clinical presentations may be recognized, 2 classic for AD (memory deficits and spatial and temporal disorientation), whereas the others are expressions of frontal impairment. The apathetic and dysexecutive subgroups could be related to orbital-medial prefrontal cortex and dorsolateral prefrontal cortex dysfunction. CONCLUSIONS: Genealogic and molecular findings provided evidence that the PSEN1 Met146Leu families from around the world analyzed in this study are related and represent a single kindred originating from Southern Italy. The marked phenotypic variability might reflect early involvement by the pathologic process of different cortical areas. Although the clinical phenotype is quite variable, the neuropathologic and biochemical characteristics of the lesions account for neurodegenerative processes unmistakably of Alzheimer nature.

Atrophy patterns in histologic vs clinical groupings of frontotemporal lobar degeneration.

OBJECTIVE: Predictable patterns of atrophy are associated with the clinical subtypes of frontotemporal dementia (FTD): behavioral variant (bvFTD), semantic dementia (SEMD), and progressive nonfluent aphasia (PNFA). Some studies of pathologic subtypes have also suggested specific atrophy patterns; however, results are inconsistent. Our aim was to test the hypothesis that clinical, but not pathologic, classification (FTD with ubiquitin inclusions [FTD-U] and FTD with tau inclusions [FTD-T]) is associated with predictable patterns of regional atrophy. METHODS: Magnetic resonance scans of nine FTD-U and six FTD-T patients (histologically confirmed) were compared with 25 controls using voxel-based morphometry (VBM). Analyses were conducted with the patient group classified according to histologic or clinical variant. Additionally, three Alzheimer pathology patients who had the syndrome of SEMD in life (FTD-A) were analyzed. RESULTS: The VBM studies in clinical variants confirmed established patterns of atrophy (SEMD, rostral temporal; bvFTD, mesial frontal; PNFA, left insula). FTD-U and FTD-T VBM results were very similar, showing severe atrophy in the temporal poles, mesial frontal lobe, and insulae. A conjunction analysis confirmed this similarity. Subgroup analysis found that SEMD associated with either FTD-T or FTD-U was associated with similar rostral temporal atrophy; however, FTD-A had a qualitatively different pattern of left hippocampal atrophy. CONCLUSIONS: While there is predictable atrophy for clinical variants of frontotemporal dementia (FTD), histologic FTD variants show no noticeable differences. Reports of specific atrophy profiles are likely the result of idiosyncrasies in small groups. Semantic dementia associated with Alzheimer pathology, however, presented a distinct atrophy pattern.

Pattern of Tau forms in CSF is altered in progressive supranuclear palsy.

Cerebrospinal fluid (CSF) total Tau levels vary widely in neurodegenerative disorders, thus being not useful in their discrimination over Alzheimer disease. No CSF marker for progressive supranuclear palsy (PSP) is currently available. The aim of this study was to characterise and measure Tau forms in order to verify the differential patterns among neurodegenerative disorders. Seventy-eight patients with neurodegenerative disorders and 26 controls were included in the study. Each patient underwent a standardised clinical and neuropsychological evaluation, MRI, and CSF total-Tau and phospho-Tau dosage. In CSF and cerebral cortex, a quantitative immunoprecipitation was developed. An extended (55 kDa), and a truncated (33 kDa) forms of Tau were recognised. CSF samples were assayed, the optical density of the two Tau forms was measured, and the ratio calculated (Tau ratio, 33 kDa/55 kDa forms). Tau ratio 33 kDa/55 kDa was significantly decreased in patients with PSP (0.46+/-0.16) when compared to controls, including healthy subjects (1.16+/-0.46, P=0.002) and Alzheimer disease (1.38+/-0.68, P<0.001), and when compared to frontotemporal dementia (0.98+/-0.30, P=0.008) or corticobasal degeneration syndrome (0.98+/-0.48, P=0.02). Moreover, in PSP patients Tau form ratio was lower than in other neurodegenerative extrapyramidal disorders, such as Parkinson disease (1.16+/-0.26, P=0.002) and dementia with lewy bodies (1.44+/-0.48, P<0.001). Tau ratio 33 kDa/55 kDa did not correlate either with demographic characteristics, cognitive performances or with motor impairment severity. Truncated Tau production shows a different pattern in PSP compared to other neurodegenerative disorders, supporting the view of disease-specific pathological pathways. These findings are promising in suggesting the identification of a marker for PSP diagnosis in clinical practice.

Abnormally phosphorylated tau is associated with neuronal and axonal loss in experimental autoimmune encephalomyelitis and multiple sclerosis.

The pathological correlate of clinical disability and progression in multiple sclerosis is neuronal and axonal loss; however, the underlying mechanisms are unknown. Abnormal phosphorylation of tau is a common feature of some neurodegenerative disorders, such as Alzheimer's disease. We investigated the presence of tau hyperphosphorylation and its relationship with neuronal and axonal loss in chronic experimental autoimmune encephalomyelitis (CEAE) and in brain samples from patients with secondary progressive multiple sclerosis. We report the novel finding of abnormal tau phosphorylation in CEAE. We further show that accumulation of insoluble tau is associated with both neuronal and axonal loss that correlates with progression from relapsing-remitting to chronic stages of EAE. Significantly, analysis of secondary progressive multiple sclerosis brain tissue also revealed abnormally phosphorylated tau and the formation of insoluble tau. Together, these observations provide the first evidence implicating abnormal tau in the neurodegenerative phase of tissue injury in experimental and human demyelinating disease.

The effect of truncated human alpha-synuclein (1-120) on dopaminergic cells in a transgenic mouse model of Parkinson's disease.

Alpha-Synuclein is thought to play an important role in the pathology of Parkinson's disease (PD). Truncated forms of this protein can be found in PD brain extracts, and these species aggregate faster and are more susceptible to oxidative stress than the full-length protein. We investigated the effect of truncated alpha-synuclein on dopaminergic cells using a transgenic mouse expressing alpha-synuclein (1-120) driven by the rat tyrosine hydroxylase promoter on a mouse alpha-synuclein null background. We found a selective reduction in the yield of dopaminergic cells from transgenic embryonic ventral mesencephalic cell cultures. However, in vivo the substantia nigra/ventral tegmentum dopaminergic cell counts were not reduced in transgenics, although these mice are known to have reduced striatal dopamine. When transplanted to the striatum in the unilateral 6-hydroxydopamine-lesioned mouse model of PD, dopaminergic cells derived from transgenic embryonic ventral mesencephala were significantly smaller at 6 weeks, and showed a trend towards being less effective at ameliorating rotational asymmetry than those from control alpha-synuclein null mice. These results suggest that alpha-synuclein (1-120) renders dopaminergic cells more susceptible to stress, which may have important implications as to how this truncated protein might contribute to dopaminergic cell death in sporadic PD.

Physiological and pathological properties of alpha-synuclein.

alpha-Synuclein belongs to a small group of natively unfolded proteins that can transiently bind to lipid membranes and acquire a partial alpha-helical conformation. Under certain pathogenic conditions, alpha-synuclein aggregates to form oligomers and insoluble fibrils with increased ss-sheet configuration. Although genetic mutations and multiplications of the gene have been found in familial cases, the mechanism by which this protein aggregates in sporadic cases of Parkinson's disease, dementia with Lewy bodies and multisystem atrophy is not fully understood. Here we review the function of alpha-synuclein and recent insight into the mechanisms by which it aggregates.

[Familial fronto-temporal dementia with brain stem ubiquitin-positive neuronal inclusions]. / Démence fronto-temporale familiale avec inclusions marquées par l'anti-ubiquitine dans le tronc cérébral.

INTRODUCTION: Fronto-temporal dementias (FTD) were described a century ago on the macroscopic basis of frontal and/or temporal lobe atrophy. Progress in neuropathology, immunohistochemistry, biochemistry and genetics has since shown that they are heterogeneous entities, encompassing many different diseases with similar clinical presentations. A few, such as tauopathies due to mutations of the gene coding for tau protein (MAPtau form a well-defined group. Definition and grouping of other types of FTD is still problematic. MATERIAL AND METHOD: We studied a family where the mother and 4/8 children were affected with FTD. Clinical presentation was typical of FTD. Onset was ill-defined with early (at age 40 years or less) personality changes. The clinical course was protracted (about 30 years). For a long period, the patients were able to live in the community in spite of obvious signs such as hyperorality and loss of verbal initiative; operative orientation as to place was preserved for a long time: a mute patient was still able to drive. Signs of extrapyramidal or motoneuron involvement were not observed. RESULTS: The genetic study failed to detect any mutation in MAPtau; the lod score for flanking markers was positive but not significant. Biochemical study showed no qualitative abnormality in tau protein. Neuropathological study of one affected subject showed brain atrophy (962 g), with elective frontal lobe involvement. Cortical nerve cell loss was more marked in superficial layers and in frontal areas; glia was inconspicuous; pseudolaminar spongiosis was present in the more severely affected zones. No argentophilic "Pick bodies" were seen; ubiquitin-positive, tau-negative round inclusions were present in the cytoplasm of fascia dentata neurones. "Tangles" were mostly restricted to the entorhinal cortex, partly correlated with tau immunoreactivity, but better with ubiquitin immunoreactivity. Large, ovoid or reniform, moderately dense, spongy, granular or filamentous argentophilic cytoplasmic nerve cell inclusions were observed. They were ubiquitin-positive, but did not react with other antibodies, particularly anti-tau. They were present in swollen nerve cells in the deeper cortical layers but were most conspicuous in the brain stem: in the magnocellular reticular nuclei (e.g. nucleus centralis pontis), in the pes pontis, in the inferior olive and in motor nuclei, especially in the trigeminal motor nucleus. They were not associated with nerve cell loss, atrophy nor pycnosis. Cerebellar relay nuclei neurones were swollen, and their cytoplasm contained argentophilic filaments. CONCLUSION: In our opinion, "ubiquitinopathy" would be non-specific and "Motor Neuron Disease-Inclusion Dementia" (MNDID) would not be satisfactory as a diagnosis for the present cases of FTD. Hopefully, progress in genetics may allow a causal, and thence definitive, classification.

Similar early clinical presentations in familial and non-familial frontotemporal dementia.

BACKGROUND: It is unclear whether there are early clinical features that can distinguish between patients with familial and non-familial frontotemporal dementia (FTD). OBJECTIVE: To compare the clinical features of FTD cases who have tau gene mutations with those of cases with a family history of FTD but no tau gene mutation, and with sporadic cases with neither feature. METHODS AND RESULTS: Comparisons of the behavioural, cognitive, and motor features in 32 FTD patients (five positive for tau gene mutations, nine familial but tau negative, and 18 tau negative sporadic) showed that age of onset and duration to diagnosis did not differ between the groups. Apathy was not observed in tau mutation positive cases, and dysexecutive signs were more frequent in familial tau mutation negative cases. Memory deficits and behavioural changes were common in all groups. CONCLUSIONS: In comparison with other neurodegenerative conditions such as Alzheimer's disease and Parkinson's disease, neither tau gene mutations nor strong familial associations confer earlier disease susceptibility.

A novel leukoencephalopathy associated with tau deposits primarily in white matter glia.

A 79-year-old woman had a 10-year history of dementia, initially presenting as non-fluent aphasia. Magnetic resonance imaging showed frontal atrophy (left greater than right) and hyperintense foci within white matter. Neuropathologically, there was severe frontal atrophy due to cortical neuronal loss with spongy change and to an even greater loss of white matter that contained prominent eosinophilic deposits. The deposits were immunoreactive for phosphorylated tau, non-reactive for Abeta and alpha-synuclein and equivocally or weakly reactive for ubiquitin. They stained with the Gallyas, Bielschowsky, and Bodian techniques. Ultrastructural examination revealed the deposits to be composed of straight filaments with a diameter of approximately 10 nm, primarily in white matter glia. Moderate loss of neurons in substantia nigra and numerous argyrophilic threads in gray and particularly white matter were noted. The precise relationship between this disorder and other frontotemporal degenerations/tauopathies, as well as the pathogenetic basis of the leukoencephalopathy, remains to be determined.

Chromosome 3 linked frontotemporal dementia (FTD-3).

BACKGROUND: The authors have identified and studied a large kindred in which frontotemporal dementia (FTD) is inherited as an autosomal dominant trait. The trait has been mapped to the pericentromeric region of chromosome 3. METHODS: The authors report on the clinical, neuroimaging, neuropsychological, and pathologic features in this unique pedigree collected during 17 years of study. RESULTS: Twenty-two individuals in three generations have been affected; the age at onset varies between 46 and 65 years. The disease presents with a predominantly frontal lobe syndrome but there is also evidence for temporal and dominant parietal lobe dysfunction. Late in the illness individuals develop a florid motor syndrome with pyramidal and extrapyramidal features. Structural imaging reveals generalized cerebral atrophy; H2 15 O-PET scanning in two individuals relatively early and late in the disease shows a striking global reduction in cerebral blood flow affecting all lobes. On macroscopic pathologic examination, there is generalized cerebral atrophy affecting the frontal lobes preferentially. Microscopically, there is neuronal loss and gliosis without specific histopathologic features. CONCLUSIONS: FTD-3 shares clinical and pathologic features with other forms of FTD and fulfills international consensus criteria for FTD. There is involvement of the parietal lobes clinically, radiologically, and pathologically in FTD-3 in contrast to some forms of FTD. This more diffuse involvement of the cerebral cortex leads to a distinctive, global pattern of reduced blood flow on PET scanning.

alpha-synuclein metabolism and aggregation is linked to ubiquitin-independent degradation by the proteasome.

alpha-Synuclein has been implicated in the pathogenesis of Parkinson's disease based on mutations in familial cases of the disease and its presence in Lewy bodies. Here we show that over-expression of wild-type human alpha-synuclein is sufficient to induce inclusion formation in SH-SY5Y cells. In this cellular model, proteasome inhibition leads to an increase of alpha-synuclein accumulation in vivo without ubiquitylation. In accordance, we find that in vitro, unmodified alpha-synuclein can be directly degraded by the 20S proteasome. These findings suggest an ubiquitin-independent mechanism of proteasomal degradation for alpha-synuclein and other natively unfolded proteins.

Pick's disease associated with the novel Tau gene mutation K369I.

Exonic and intronic mutations in Tau cause neurodegenerative syndromes characterized by frontotemporal dementia and filamentous tau protein deposits. We describe a K369I missense mutation in exon 12 of Tau in a patient with a pathology typical of sporadic Pick's disease. The proband presented with severe personality changes, followed by loss of cognitive function. Detailed postmortem examination of the brain showed atrophy, which was most pronounced in the temporal lobes; and numerous tau-immunoreactive Pick bodies and Pick cells in the neocortex and the hippocampal formation, as well as in subcortical brain regions. Their appearance and staining characteristics were indistinguishable from those of sporadic Pick's disease. However, immunoblot analysis of sarkosyl-insoluble tau showed three major bands of 60, 64, and 68 kDa, consistent with the presence of 3- and 4-repeat tau isoforms, as in Alzheimer's disease. Isolated tau filaments were irregularly twisted ribbons, with a small number of Alzheimer-type paired helical filaments. In the presence of heparin, tau proteins with the K369I mutation formed short, slender filaments. Biochemically, recombinant tau proteins with the K369I mutation showed reduced ability to promote microtubule assembly, suggesting that this may be the primary effect of the mutation by providing a pool of aberrant tau for filament assembly. Taken together, results indicate that the K369I mutation in Tau can cause a dementing disease with a neuropathology like that of Pick's disease.

Familial frontotemporal dementia with ubiquitin-positive inclusions is linked to chromosome 17q21-22.

Hereditary frontotemporal dementia (FTD) is an autosomal dominant neurodegenerative disorder that is associated with mutations in the tau gene and with the pathological accumulation of hyperphosphorylated tau protein in affected brain cells in about a quarter of cases. However, most FTD families have no demonstrable tau mutations. Here we describe the clinical and neuropathological features of a large family with hereditary FTD. Genetic analysis showed strong evidence for linkage to chromosome 17q21-22 (maximum lod score 3.46, theta = 0 for marker D17S950), but mutations in the tau gene were not found. Clinical symptoms, neuropsychological deficits and neuroimaging findings of affected family members were similar to sporadic and tau-related FTD. The mean age at onset was 61.2 years, with loss of initiative and decreased spontaneous speech as the most prominent presenting symptoms. Pathological examination of the brains of two affected family members showed non-specific neuronal degeneration with dense cytoplasmic ubiquitin-positive inclusions in neurones of the second layer of the frontotemporal cortex and dentate gyrus of the hippocampus. In a number of neurones these inclusions appeared to be located inside the nucleus, although due to the small number of these inclusions this localization could not be confirmed by electron microscopy. The inclusions were not stained by tau, alpha-synuclein or polyglutamine antibodies. Biochemical analysis of soluble tau did not reveal abnormalities in tau isoform distribution and analysis of mRNA showed the presence of both three- and four-repeat transcripts. This is the first report of ubiquitin-positive, tau-negative inclusions in an FTD family with significant linkage to chromosome 17q21-22. Further characterization of the ubiquitin-positive inclusions may clarify the neurodegenerative pathways involved in this subtype of FTD.

Tau gene mutations and neurodegeneration.

Abundant neurofibrillary lesions made of the microtubule-associated protein tau constitute a defining neuropathological characteristic of Alzheimer's disease. Filamentous tau protein deposits are also the defining neuropathological characteristic of other neurodegenerative diseases, many of which are frontotemporal dementias or movement disorders, such as Pick's disease, progressive supranuclear palsy and corticobasal degeneration. It is well established that the distribution of tau pathology correlates with the presence of symptoms of disease. However, until recently, there was no genetic evidence linking dysfunction of tau protein to neurodegeneration and dementia. This has now changed with the discovery of close to 20 mutations in the tau gene in frontotemporal dementia with Parkinsonism linked to chromosome 17. All cases with tau mutations examined to date have shown an abundant filamentous tau pathology in brain cells. Pathological heterogeneity is determined to a large extent by the location of mutations in tau. Known mutations are either coding region or intronic mutations located close to the splice-donor site of the intron downstream of exon 10. Most coding region mutations produce a reduced ability of tau to interact with microtubules. Several of these mutations also promote sulphated glycosaminoglycan-induced assembly of tau into filaments. Intronic mutations and some coding region mutations produce increased splicing in of exon 10, resulting in an overexpression of four-repeat tau isoforms. Thus a normal ratio of three-repeat to four-repeat tau isoforms is essential for preventing the development of tau pathology. The new work has shown that dysfunction of tau protein can cause neurodegeneration and dementia.