Abundant copathologies of polyglucosan bodies, frontotemporal lobar degeneration with TDP-43 inclusions and ageing-related tau astrogliopathy in a family with a GBE1 mutation.

AIMS: Adult polyglucosan body disease (APBD) is a progressive neurogenetic disorder caused by 1,4-alpha-glucan branching enzyme 1 (GBE1) mutation with an accumulation of polyglucosan bodies (PBs) in the central and peripheral nervous systems as a pathological hallmark. Here, we report two siblings in a family with a GBE1 mutation with prominent frontotemporal lobar degeneration with TAR DNA-binding protein 43 (FTLD-TDP) and ageing-related tau astrogliopathy (ARTAG) copathologies with PBs in the central nervous system. METHODS: Whole-genome sequencing (WGS) followed by Sanger sequencing (SS) was performed on three affected and two unaffected siblings in a pedigree diagnosed with familial frontotemporal dementia. Out of the affected siblings, autopsies were conducted on two cases, and brain samples were used for biochemical and histological analyses. Brain sections were stained with haematoxylin and eosin and immunostained with antibodies against ubiquitin, tau, amyloid ß, α-synuclein, TDP-43 and fused in sarcoma (FUS). RESULTS: A novel single nucleotide deletion in GBE1, c.1280delG, was identified, which is predicted to result in a reading frameshift, p.Gly427Glufs*9. This variant segregated with disease in the family, is absent from population databases and is predicted to cause loss of function, a known genetic mechanism for APBD. The affected siblings showed a greater than 50% decrease in GBE protein levels. Immunohistochemical analysis revealed widespread FTLD-TDP (type A) and ARTAG pathologies as well as PBs in the brains of two affected siblings for whom an autopsy was performed. CONCLUSIONS: This is the first report of a family with several individuals with a FTD clinical phenotype and underlying copathologies of APBD, FTLD-TDP and ARTAG with a segregating GBE1 loss-of-function mutation in affected siblings. The finding of copathologies of APBD and FTLD-TDP suggests these processes may share a disease mechanism resulting from this GBE1 mutation.

Distinct characteristics of limbic-predominant age-related TDP-43 encephalopathy in Lewy body disease.

Limbic-predominant age-related TDP-43 encephalopathy (LATE) is characterized by the accumulation of TAR-DNA-binding protein 43 (TDP-43) aggregates in older adults. LATE coexists with Lewy body disease (LBD) as well as other neuropathological changes including Alzheimer's disease (AD). We aimed to identify the pathological, clinical, and genetic characteristics of LATE in LBD (LATE-LBD) by comparing it with LATE in AD (LATE-AD), LATE with mixed pathology of LBD and AD (LATE-LBD + AD), and LATE alone (Pure LATE). We analyzed four cohorts of autopsy-confirmed LBD (n = 313), AD (n = 282), LBD + AD (n = 355), and aging (n = 111). We assessed the association of LATE with patient profiles including LBD subtype and AD neuropathologic change (ADNC). We studied the morphological and distributional differences between LATE-LBD and LATE-AD. By frequency analysis, we staged LATE-LBD and examined the association with cognitive impairment and genetic risk factors. Demographic analysis showed LATE associated with age in all four cohorts and the frequency of LATE was the highest in LBD + AD followed by AD, LBD, and Aging. LBD subtype and ADNC associated with LATE in LBD or AD but not in LBD + AD. Pathological analysis revealed that the hippocampal distribution of LATE was different between LATE-LBD and LATE-AD: neuronal cytoplasmic inclusions were more frequent in cornu ammonis 3 (CA3) in LATE-LBD compared to LATE-AD and abundant fine neurites composed of C-terminal truncated TDP-43 were found mainly in CA2 to subiculum in LATE-LBD, which were not as numerous in LATE-AD. Some of these fine neurites colocalized with phosphorylated α-synuclein. LATE-LBD staging showed LATE neuropathological changes spread in the dentate gyrus and brainstem earlier than in LATE-AD. The presence and prevalence of LATE in LBD associated with cognitive impairment independent of either LBD subtype or ADNC; LATE-LBD stage also associated with the genetic risk variants of TMEM106B rs1990622 and GRN rs5848. These data highlight clinicopathological and genetic features of LATE-LBD.

α-Synuclein Spread from Olfactory Bulb Causes Hyposmia, Anxiety, and Memory Loss in BAC-SNCA Mice.

BACKGROUND: Patients with Parkinson's disease (PD) show motor symptoms as well as various non-motor symptoms. Postmortem studies of PD have suggested that initial alpha-synuclein (α-Syn) pathology develops independently in the olfactory bulb and lower brainstem, spreading from there stereotypically. However, it remains unclear how these two pathological pathways contribute to the clinicopathological progression of PD. OBJECTIVE: The objective of this study was to examine the clinicopathological contribution of α-Syn spread from the olfactory bulb. METHODS: We conducted pathological and behavioral analyses of human α-Syn bacterial artificial chromosome transgenic mice injected with α-Syn preformed fibrils into the bilateral olfactory bulb up to 10 months postinjection. RESULTS: α-Syn preformed fibril injections induced more widespread α-Syn pathology in the transgenic mice than that in wild-type mice. Severe α-Syn pathology in the transgenic mice injected with α-Syn preformed fibrils was initially observed along the olfactory pathway and later in the brain regions that are included in the limbic system and have connections with it. The α-Syn pathology was accompanied by regional atrophy, neuron loss, reactive astrogliosis, and microglial activation, which were remarkable in the hippocampus. Behavioral analyses revealed hyposmia, followed by anxiety-like behavior and memory impairment, but not motor dysfunction, depression-like behavior, or circadian rhythm disturbance. CONCLUSION: Our data suggest that α-Syn spread from the olfactory bulb mainly affects the olfactory pathway and limbic system as well as its related regions, leading to the development of hyposmia, anxiety, and memory loss in PD. © 2021 International Parkinson and Movement Disorder Society.

α-Synuclein BAC transgenic mice exhibit RBD-like behaviour and hyposmia: a prodromal Parkinson's disease model.

Parkinson's disease is one of the most common movement disorders and is characterized by dopaminergic cell loss and the accumulation of pathological α-synuclein, but its precise pathogenetic mechanisms remain elusive. To develop disease-modifying therapies for Parkinson's disease, an animal model that recapitulates the pathology and symptoms of the disease, especially in the prodromal stage, is indispensable. As subjects with α-synuclein gene (SNCA) multiplication as well as point mutations develop familial Parkinson's disease and a genome-wide association study in Parkinson's disease has identified SNCA as a risk gene for Parkinson's disease, the increased expression of α-synuclein is closely associated with the aetiology of Parkinson's disease. In this study we generated bacterial artificial chromosome transgenic mice harbouring SNCA and its gene expression regulatory regions in order to maintain the native expression pattern of α-synuclein. Furthermore, to enhance the pathological properties of α-synuclein, we inserted into SNCA an A53T mutation, two single-nucleotide polymorphisms identified in a genome-wide association study in Parkinson's disease and a Rep1 polymorphism, all of which are causal of familial Parkinson's disease or increase the risk of sporadic Parkinson's disease. These A53T SNCA bacterial artificial chromosome transgenic mice showed an expression pattern of human α-synuclein very similar to that of endogenous mouse α-synuclein. They expressed truncated, oligomeric and proteinase K-resistant phosphorylated forms of α-synuclein in the regions that are specifically affected in Parkinson's disease and/or dementia with Lewy bodies, including the olfactory bulb, cerebral cortex, striatum and substantia nigra. Surprisingly, these mice exhibited rapid eye movement (REM) sleep without atonia, which is a key feature of REM sleep behaviour disorder, at as early as 5 months of age. Consistent with this observation, the REM sleep-regulating neuronal populations in the lower brainstem, including the sublaterodorsal tegmental nucleus, nuclei in the ventromedial medullary reticular formation and the pedunculopontine nuclei, expressed phosphorylated α-synuclein. In addition, they also showed hyposmia at 9 months of age, which is consistent with the significant accumulation of phosphorylated α-synuclein in the olfactory bulb. The dopaminergic neurons in the substantia nigra pars compacta degenerated, and their number was decreased in an age-dependent manner by up to 17.1% at 18 months of age compared to wild-type, although the mice did not show any related locomotor dysfunction. In conclusion, we created a novel mouse model of prodromal Parkinson's disease that showed RBD-like behaviour and hyposmia without motor symptoms.

How does acyl chain length affect thermotropic phase behavior of saturated diacylphosphatidylcholine-cholesterol binary bilayers?

Thermotropic phase behavior of diacylphosphatidylcholine (CnPC)-cholesterol binary bilayers (n=14-16) was examined by fluorescence spectroscopy using 6-propionyl-2-(dimethylamino)naphthalene (Prodan) and differential scanning calorimetry. The former technique can detect structural changes of the bilayer in response to the changes in polarity around Prodan molecules partitioned in a relatively hydrophilic region of the bilayer, while the latter is sensitive to the conformational changes of the acyl chains. On the basis of the data from both techniques, we propose possible temperature T-cholesterol composition Xch phase diagrams for these binary bilayers. A notable feature of our phase diagrams, including our previous results for diheptadecanoylphosphatidylcholine (C17PC) and distearoylphosphatidylcholine (C18PC), is that there is a peritectic-like point around Xch=0.15, which can be interpreted as indicating the formation of a 1:6-complex of cholesterol and CnPCs within the binary bilayer irrespective of the acyl chain length. We could give a reasonable explanation for such complex formation using the modified superlattice view. Our results also showed that the Xch value of the abolition of the main transition is almost constant for n=14-17 (ca. 0.33), while it increases to ca. 0.50 for n=18. By contrast, a biphasic n-dependence of Xch was observed for the abolition of the pretransition, suggesting that there are at least two antagonistic n-dependent factors. We speculate that this could be explained by the enhancement of the van der Waals interaction with increases in n and the weakening of the repulsion between the neighboring headgroups with decreases in n.

Dynamic endocannabinoid-mediated neuromodulation of retinal circadian circuitry.

Circadian rhythms are biological rhythms that originate from the "master circadian clock," called the suprachiasmatic nucleus (SCN). SCN orchestrates the circadian rhythms using light as a chief zeitgeber, enabling humans to synchronize their daily physio-behavioral activities with the Earth's light-dark cycle. However, chronic/ irregular photic disturbances from the retina via the retinohypothalamic tract (RHT) can disrupt the amplitude and the expression of clock genes, such as the period circadian clock 2, causing circadian rhythm disruption (CRd) and associated neuropathologies. The present review discusses neuromodulation across the RHT originating from retinal photic inputs and modulation offered by endocannabinoids as a function of mitigation of the CRd and associated neuro-dysfunction. Literature indicates that cannabinoid agonists alleviate the SCN's ability to get entrained to light by modulating the activity of its chief neurotransmitter, i.e., γ-aminobutyric acid, thus preventing light-induced disruption of activity rhythms in laboratory animals. In the retina, endocannabinoid signaling modulates the overall gain of the retinal ganglion cells by regulating the membrane currents (Ca2+, K+, and Cl- channels) and glutamatergic neurotransmission of photoreceptors and bipolar cells. Additionally, endocannabinoids signalling also regulate the high-voltage-activated Ca2+ channels to mitigate the retinal ganglion cells and intrinsically photosensitive retinal ganglion cells-mediated glutamate release in the SCN, thus regulating the RHT-mediated light stimulation of SCN neurons to prevent excitotoxicity. As per the literature, cannabinoid receptors 1 and 2 are becoming newer targets in drug discovery paradigms, and the involvement of endocannabinoids in light-induced CRd through the RHT may possibly mitigate severe neuropathologies.

Exercise is more effective than diet control in preventing high fat diet-induced ß-amyloid deposition and memory deficit in amyloid precursor protein transgenic mice.

Accumulating evidence suggests that some dietary patterns, specifically high fat diet (HFD), increase the risk of developing sporadic Alzheimer disease (AD). Thus, interventions targeting HFD-induced metabolic dysfunctions may be effective in preventing the development of AD. We previously demonstrated that amyloid precursor protein (APP)-overexpressing transgenic mice fed HFD showed worsening of cognitive function when compared with control APP mice on normal diet. Moreover, we reported that voluntary exercise ameliorates HFD-induced memory impairment and ß-amyloid (Aß) deposition. In the present study, we conducted diet control to ameliorate the metabolic abnormality caused by HFD on APP transgenic mice and compared the effect of diet control on cognitive function with that of voluntary exercise as well as that of combined (diet control plus exercise) treatment. Surprisingly, we found that exercise was more effective than diet control, although both exercise and diet control ameliorated HFD-induced memory deficit and Aß deposition. The production of Aß was not different between the exercise- and the diet control-treated mice. On the other hand, exercise specifically strengthened the activity of neprilysin, the Aß-degrading enzyme, the level of which was significantly correlated with that of deposited Aß in our mice. Notably, the effect of the combination treatment (exercise and diet control) on memory and amyloid pathology was not significantly different from that of exercise alone. These studies provide solid evidence that exercise is a useful intervention to rescue HFD-induced aggravation of cognitive decline in transgenic model mice of AD.

Rapid Induction of Dopaminergic Neuron Loss Accompanied by Lewy Body-Like Inclusions in A53T BAC-SNCA Transgenic Mice.

Parkinson's disease (PD), the most common neurodegenerative movement disorder, is characterized by dopaminergic neuron loss in the substantia nigra pars compacta (SNpc) and intraneuronal α-synuclein (α-syn) inclusions. It is highly needed to establish a rodent model that recapitulates the clinicopathological features of PD within a short period to efficiently investigate the pathological mechanisms and test disease-modifying therapies. To this end, we analyzed three mouse lines, i.e., wild-type mice, wild-type human α-syn bacterial artificial chromosome (BAC) transgenic (BAC-SNCA Tg) mice, and A53T human α-syn BAC transgenic (A53T BAC-SNCA Tg) mice, receiving dorsal striatum injections of human and mouse α-syn preformed fibrils (hPFFs and mPFFs, respectively). mPFF injections induced more severe α-syn pathology in most brain regions, including the ipsilateral SNpc, than hPFF injections in all genotypes at 1-month post-injection. Although these Tg mouse lines expressed a comparable amount of α-syn in the brains, the mPFF-injected A53T BAC-SNCA Tg mice exhibited the most severe α-syn pathology as early as 0.5-month post-injection. The mPFF-injected A53T BAC-SNCA Tg mice showed a 38% reduction in tyrosine hydroxylase (TH)-positive neurons in the ipsilateral SNpc, apomorphine-induced rotational behavior, and motor dysfunction at 2 months post-injection. These data indicate that the extent of α-syn pathology induced by α-syn PFF injection depends on the types of α-syn PFFs and exogenously expressed α-syn in Tg mice. The mPFF-injected A53T BAC-SNCA Tg mice recapitulate the key features of PD more rapidly than previously reported mouse models, suggesting their usefulness for testing disease-modifying therapies as well as analyzing the pathological mechanisms.

Hemosiderin Detection inside the Mammillary Bodies Using Quantitative Susceptibility Mapping on Patients with Wernicke-Korsakoff Syndrome.

Hemorrhage inside the mammillary bodies (MMBs) is known to be one of the findings of Wernicke encephalopathy. Brain MRI of two patients with Wernicke-Korsakoff syndrome (WKS) demonstrated high susceptibility values representing hemosiderin deposition in MMBs by using quantitative susceptibility mapping (QSM). QSM provided additional information of susceptibility values to susceptibility-weighted imaging in diagnosis of WKS.

Failure of DNA double-strand break repair by tau mediates Alzheimer's disease pathology in vitro.

DNA double-strand break (DSB) is the most severe form of DNA damage and accumulates with age, in which cytoskeletal proteins are polymerized to repair DSB in dividing cells. Since tau is a microtubule-associated protein, we investigate whether DSB is involved in tau pathologies in Alzheimer's disease (AD). First, immunohistochemistry reveals the frequent coexistence of DSB and phosphorylated tau in the cortex of AD patients. In vitro studies using primary mouse cortical neurons show that non-p-tau accumulates perinuclearly together with the tubulin after DSB induction with etoposide, followed by the accumulation of phosphorylated tau. Moreover, the knockdown of endogenous tau exacerbates DSB in neurons, suggesting the protective role of tau on DNA repair. Interestingly, synergistic exposure of neurons to microtubule disassembly and the DSB strikingly augments aberrant p-tau aggregation and apoptosis. These data suggest that DSB plays a pivotal role in AD-tau pathology and that the failure of DSB repair leads to tauopathy.

Brain Microvascular Pericytes in Vascular Cognitive Impairment and Dementia.

Pericytes are unique, multi-functional mural cells localized at the abluminal side of the perivascular space in microvessels. Originally discovered in 19th century, pericytes had drawn less attention until decades ago mainly due to lack of specific markers. Recently, however, a growing body of evidence has revealed that pericytes play various important roles: development and maintenance of blood-brain barrier (BBB), regulation of the neurovascular system (e.g., vascular stability, vessel formation, cerebral blood flow, etc.), trafficking of inflammatory cells, clearance of toxic waste products from the brain, and acquisition of stem cell-like properties. In the neurovascular unit, pericytes perform these functions through coordinated crosstalk with neighboring cells including endothelial, glial, and neuronal cells. Dysfunction of pericytes contribute to a wide variety of diseases that lead to cognitive impairments such as cerebral small vessel disease (SVD), acute stroke, Alzheimer's disease (AD), and other neurological disorders. For instance, in SVDs, pericyte degeneration leads to microvessel instability and demyelination while in stroke, pericyte constriction after ischemia causes a no-reflow phenomenon in brain capillaries. In AD, which shares some common risk factors with vascular dementia, reduction in pericyte coverage and subsequent microvascular impairments are observed in association with white matter attenuation and contribute to impaired cognition. Pericyte loss causes BBB-breakdown, which stagnates amyloid ß clearance and the leakage of neurotoxic molecules into the brain parenchyma. In this review, we first summarize the characteristics of brain microvessel pericytes, and their roles in the central nervous system. Then, we focus on how dysfunctional pericytes contribute to the pathogenesis of vascular cognitive impairment including cerebral 'small vessel' and 'large vessel' diseases, as well as AD. Finally, we discuss therapeutic implications for these disorders by targeting pericytes.

Limited spread of pathology within the brainstem of α-synuclein BAC transgenic mice inoculated with preformed fibrils into the gastrointestinal tract.

Parkinson's disease (PD) is pathologically characterized by intraneuronal α-synuclein (α-Syn) aggregates called Lewy bodies (LBs) as well as the loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc). On the basis of autopsy studies, Braak et al. hypothesized that Lewy pathology initially occurs in the enteric nervous system, subsequently spreading to the dorsal motor nucleus of the vagus nerve (dmX) and then ascending in the brainstem to the SNpc. However, this hypothetical progression lacks adequate experimental evidence. We previously reported that inoculation of α-Syn preformed fibrils (PFFs) into the gastric wall of wild-type (WT) mice induced LB-like α-Syn aggregates in the dmX via the vagus nerve. However, α-Syn pathology did not spread beyond the dmX up to 12 months postinoculation. In the present study, we inoculated α-Syn PFFs into the gastric wall of bacterial artificial chromosome (BAC) transgenic mice harboring the human α-Syn gene with an A53 T mutation and analyzed the pathology. The transgenic mice had ∼1.5-fold overexpression of α-Syn in the brains and ∼6-fold overexpression of α-Syn in the stomach compared with WT mice. After inoculation of α-Syn PFFs, the transgenic mice developed a higher number of phosphorylated α-Syn (p-α-Syn)-positive neurons in the dmX compared with similarly inoculated WT mice. However, the number of p-α-Syn-positive neurons in the dmX decreased over time, and α-Syn pathology was not observed in other brain regions except in the ambiguous nucleus up to 8 months postinoculation. Taken together, BAC transgenic expression of α-Syn facilitated induction of α-Syn pathology in the brainstem, but not subsequent caudo-rostral spread in accordance with Braak's hypothesis.

Cell-to-Cell Transmission of Tau and α-Synuclein.

The stereotypical spread of pathological protein inclusions and clinicopathological heterogeneity are well described in neurodegenerative diseases. Accumulating evidence suggests that the former can be attributed to consecutive cell-to-cell transmission of pathological proteins between anatomically connected brain regions, while the latter has been hypothesized to result from the spread of conformationally distinct pathological protein aggregates, or strains. These emerging concepts have dramatically changed our understanding of neurodegenerative diseases. In this review, we first summarize the background and recent findings underpinning these concepts with a focus on two major pathological proteins: tau and α-synuclein. We then discuss their clinical implications for tauopathies and synucleinopathies and propose a working hypothesis for future research.

Loss of capillary pericytes and the blood-brain barrier in white matter in poststroke and vascular dementias and Alzheimer's disease.

White matter (WM) disease is associated with disruption of the gliovascular unit, which involves breach of the blood-brain barrier (BBB). We quantified pericytes as components of the gliovascular unit and assessed their status in vascular and other common dementias. Immunohistochemical and immunofluorescent methods were developed to assess the distribution and quantification of pericytes connected to the frontal lobe WM capillaries. Pericytes with a nucleus were identified by collagen 4 (COL4) and platelet-derived growth factor receptor-ß (PDGFR-ß) antibodies with further verification using PDGFR-ß-specific ELISA. We evaluated a total of 124 post-mortem brains from subjects with post-stroke dementia (PSD), vascular dementia (VaD), Alzheimer's disease (AD), AD-VaD (Mixed) and post-stroke non-demented (PSND) stroke survivors as well as normal aging controls. COL4 and PDGFR-ß reactive pericytes adopted the characteristic "crescent" or nodule-like shapes around capillary walls. We estimated densities of pericyte somata to be 225 ±38 and 200 ±13 (SEM) per COL4 mm2 area or 2.0 ± 0.1 and 1.7 ± 0.1 per mm capillary length in young and older aging controls. Remarkably, WM pericytes were reduced by ~35%-45% in the frontal lobe of PSD, VaD, Mixed and AD subjects compared to PSND and controls subjects (P < 0.001). We also found pericyte numbers were correlated with PDGFR-ß reactivity in the WM. Our results first demonstrate a reliable method to quantify COL4-positive pericytes and then, indicate that deep WM pericytes are decreased across different dementias including PSD, VaD, Mixed and AD. Our findings suggest that downregulation of pericytes is associated with the disruption of the BBB in the deep WM in several aging-related dementias.

Correction to: Inoculation of α-synuclein preformed fibrils into the mouse gastrointestinal tract induces Lewy body-like aggregates in the brainstem via the vagus nerve.

The original article [1] mistakenly omitted essential information regarding Fig. 1c; thus, the authors would like to note that Fig. 1c describes transmission electron microscopy of α-Syn PFFs before sonication.

Slow Progressive Accumulation of Oligodendroglial Alpha-Synuclein (α-Syn) Pathology in Synthetic α-Syn Fibril-Induced Mouse Models of Synucleinopathy.

Synucleinopathies are composed of Parkinson disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). Alpha-synuclein (α-Syn) forms aggregates mainly in neurons in PD and DLB, while oligodendroglial α-Syn aggregates are characteristic of MSA. Recent studies have demonstrated that injections of synthetic α-Syn preformed fibrils (PFFs) into the brains of wild-type (WT) animals induce intraneuronal α-Syn aggregates and the subsequent interneuronal transmission of α-Syn aggregates. However, injections of α-Syn PFFs or even brain lysates of patients with MSA have not been reported to induce oligodendroglial α-Syn aggregates, raising questions about the pathogenesis of oligodendroglial α-Syn aggregates in MSA. Here, we report that WT mice injected with mouse α-Syn (m-α-Syn) PFFs develop neuronal α-Syn pathology after short postinjection (PI) intervals on the scale of weeks, while oligodendroglial α-Syn pathology emerges after longer PI intervals of several months. Abundant oligodendroglial α-Syn pathology in white matter at later time points is reminiscent of MSA. Furthermore, comparison between young and aged mice injected with m-α-Syn PFFs revealed that PI intervals rather than aging correlate with oligodendroglial α-Syn aggregation. These results provide novel insights into the pathological mechanisms of oligodendroglial α-Syn aggregation in MSA.

A new interpretation of eutectic behavior for distearoylphosphatidylcholine-cholesterol binary bilayer membrane.

We investigated the thermotropic phase behavior of the distearoylphosphatidylcholine (DSPC)-cholesterol binary bilayer membrane as a function of the cholesterol composition (X(ch)) by fluorescence spectroscopy using 6-propionyl-2-(dimethylamino)naphthalene (Prodan) and differential scanning calorimetry (DSC). The fluorescence spectra, each of which has a single maximum, showed that the wavelength at the maximum intensity (lambda(max)) changed depending on the bilayer state: ca. 440 nm for the lamellar gel (L(beta)' or L(beta)) and the liquid ordered (L(o)) phases, ca. 470 nm for the ripple gel (P(beta)') phase and ca. 490 nm for the liquid crystalline (L(alpha)) phase, respectively. The transition temperatures were determined from the temperature dependences of the lambda(max) and endothermic peaks of the DSC thermograms. Both measurements showed that the pretransition disappears around X(ch)=0.035. The constructed temperature-X(ch) phase diagram indicated that the phase behavior of the binary bilayer membrane at X(ch)< or =0.15 is similar to that of general liquid-solid equilibrium for a binary system where both components are completely miscible in the liquid phase and completely immiscible in the solid phase. It was also revealed that the diagram has two characteristic points: a congruent melting point at X(ch)=0.08 and a peritectic-like point at X(ch)=0.15. The hexagonal lattice model was used for the interpretation of the phase behavior of the binary bilayer membrane. These characteristic compositions well correspond to the bilayer states in each of which cholesterol molecules are regularly distributed in the hexagonal lattice in a different way. That is, each composition of 0.035, 0.08 and 0.15 is nearly equal to that for the binary bilayer membrane which is entirely occupied with units, each composed of a cholesterol and 30 surrounding DSPC molecules within the next-next-next nearest neighbor sites (Unit (1:30): L(beta)(1:30)), with units, each of a cholesterol and 12 surrounding DSPC molecules within the next nearest sites (Unit (1:12): L(beta)(1:12)) or with units, each of a cholesterol and 6 surrounding DSPC molecules at the nearest neighbor sites (Unit (1:6): L(beta)(1:6)), respectively. Therefore, the eutectic behavior observed in the phase diagram was fully explainable in terms of a kind of phase separation between two different types of regions with different types of regular distributions of cholesterol. Further, the L(o) phase was found in the higher X(ch)-region (X(ch)>0.15). No endothermic peak over the temperature range from 10 to 80 degrees C at X(ch)=0.50 suggested that the single L(o) phase can exist at X(ch)>0.50.

Lateral phase separation in cholesterol/diheptadecanoylphosphatidylcholine binary bilayer membrane.

We investigated the phase behavior of cholesterol/diheptadecanoylphosphatidylcholine (C17:0-PC) binary bilayer membrane as a function of the cholesterol composition (X(ch)) by fluorescence spectroscopy using 6-propionyl-2-(dimethylamino)naphthalene (Prodan) and differential scanning calorimetry (DSC). The fluorescence spectra showed that the wavelength at the maximum intensity (lambda(max)) changed depending on the bilayer state: ca. 440 nm for the lamellar gel (L'(beta) or L(beta)) and the liquid ordered (L(o)) phases and ca. 490 nm for the liquid-crystalline (L(alpha)) phase. The transition temperatures were determined from the temperature dependence of lambda(max) and endothermic peaks of the DSC thermograms. Both measurements showed that the pre- and main transition disappear around X(ch)=0.05 and 0.30, respectively. The constructed temperature-X(ch) phase diagram resembled a typical phase diagram for a eutectic binary mixture containing a peritectic point. The presence of a peritectic point at X(ch)=0.15 suggested that a complex of cholesterol and C17:0-PC is stoichiometrically formed in the gel phase. Consideration based on the hexagonal lattice model revealed that the compositions of 0.05 and 0.15 correspond to the bilayer states where cholesterol molecules are regularly distributed in different ways. The former is nearly equal to the composition for the membrane occupied entirely with Units (1:18), composed of a cholesterol and 18 surrounding C17:0-PC molecules within the next-next nearest neighbor sites. The latter is represented by a Unit (1:6), including a cholesterol and 6 surrounding C17:0-PC molecules. Further, the disappearance of the main transition at X(ch)=0.30 indicates that the pure L(o) phase can exist in X(ch)>0.30. The eutectic behavior observed in the phase diagram was explainable in terms of phase separation between two different types of regions with different types of regular distributions of cholesterol.

Inoculation of α-synuclein preformed fibrils into the mouse gastrointestinal tract induces Lewy body-like aggregates in the brainstem via the vagus nerve.

BACKGROUND: Intraneuronal α-synuclein (α-Syn) aggregates known as Lewy bodies (LBs) and the loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) are the pathological hallmarks of Parkinson's disease (PD). Braak's hypothesis based on autopsy studies suggests that Lewy pathology initially occurs in the enteric nervous system (ENS) and then travels retrogradely to the dorsal motor nucleus of the vagus nerve (dmX), proceeding from there in a caudo-rostral direction. Recent evidence that α-Syn aggregates propagate between interconnected neurons supports this hypothesis. However, there is no direct evidence demonstrating this transmission from the ENS to the dmX and then to the SNpc. METHODS: We inoculated α-Syn preformed fibrils (PFFs) or phosphate-buffered saline (PBS) into the mouse gastric wall and analyzed the progression of the pathology. RESULTS: The mice inoculated with α-Syn PFFs, but not with PBS, developed phosphorylated α-Syn (p-α-Syn)-positive LB-like aggregates in the dmX at 45 days postinoculation. This aggregate formation was completely abolished when vagotomy was performed prior to inoculation of α-Syn PFFs, suggesting that the aggregates in the dmX were retrogradely induced via the vagus nerve. Unexpectedly, the number of neurons containing p-α-Syn-positive aggregates in the dmX decreased over time, and no further caudo-rostral propagation beyond the dmX was observed up to 12 months postinoculation. P-α-Syn-positive aggregates were also present in the myenteric plexus at 12 months postinoculation. However, unlike in patients with PD, there was no cell-type specificity in neurons containing those aggregates in this model. CONCLUSIONS: These results indicate that α-Syn PFF inoculation into the mouse gastrointestinal tract can induce α-Syn pathology resembling that of very early PD, but other factors are apparently required if further progression of PD pathology is to be replicated in this animal model.

Pericyte-derived bone morphogenetic protein 4 underlies white matter damage after chronic hypoperfusion.

Subcortical small vessel disease (SVD) is characterized by white matter damage resulting from arteriolosclerosis and chronic hypoperfusion. Transforming growth factor beta 1 (TGFB1) is dysregulated in the hereditary SVD, CARASIL (cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy). However, very little is known about the role of the largest group in the TGFB superfamily - the bone morphogenetic proteins (BMPs) - in SVD pathogenesis. The aim of this study was to characterize signaling abnormalities of BMPs in sporadic SVD. We examined immunostaining of TGFB1 and BMPs (BMP2/BMP4/BMP6/BMP7/BMP9) in a total of 19 post-mortem human brain samples as follows: 7 SVD patients (4 males, 76-90 years old); 6 Alzheimer's disease (AD) patients (2 males, 67-93 years old) and 6 age-matched disease controls (3 males, 68-78 years old). We subsequently investigated the effects of oxygen-glucose deprivation and BMP4 addition on cultured cells. Furthermore, adult mice were subjected to chronic cerebral hypoperfusion using bilateral common carotid artery stenosis, followed by continuous intracerebroventricular infusion of the BMP antagonist, noggin. In the SVD cases, BMP4 was highly expressed in white matter pericytes. Oxygen-glucose deprivation induced BMP4 expression in cultured pericytes in vitro. Recombinant BMP4 increased the number of cultured endothelial cells and pericytes and converted oligodendrocyte precursor cells into astrocytes. Chronic cerebral hypoperfusion in vivo also upregulated BMP4 with concomitant white matter astrogliogenesis and reduced oligodendrocyte lineage cells, both of which were suppressed by intracerebroventricular noggin infusion. Our findings suggest ischemic white matter damage evolves in parallel with BMP4 upregulation in pericytes. BMP4 promotes angiogenesis, but induces astrogliogenesis at the expense of oligodendrocyte precursor cell proliferation and maturation, thereby aggravating white matter damage. This may explain white matter vulnerability to chronic hypoperfusion. The regulation of BMP4 signaling is a potential therapeutic strategy for treating SVD.