ABSTRACT
INTRODUCTION: Age-related magnetic resonance imaging (MRI) T2 white matter hyperintensities (WMHs) are common and associated with neurological decline. We investigated the histopathological underpinnings of MRI WMH and surrounding normal appearing white matter (NAWM), with a focus on astroglial phenotypes. METHODS: Brain samples from 51 oldest old Oregon Alzheimer's Disease Research Center participants who came to autopsy underwent post mortem (PM) 7 tesla MRI with targeted histopathological sampling of WMHs and NAWM. Stained slides were digitized and quantified. Mixed-effects models determined differences in molecular characteristics between WMHs and the NAWM and across NAWM. RESULTS: PM MRI-targeted WMHs are characterized by demyelination, microglial activation, and prominent astrocytic alterations, including disrupted aquaporin (AQP) expression. Similar changes occur within the surrounding NAWM in a pattern of decreasing severity with increased distance from WMHs. DISCUSSION: Decreased AQP expression within WMH and proximal NAWM suggest an overwhelmed system wherein water homeostasis is no longer maintained, contributing to WM damage in older individuals. HIGHLIGHTS: Post mortem magnetic resonance imaging (MRI) was used to characterize the pathology of white matter hyperintensities (WMHs) and surrounding normal appearing white matter (NAWM). Stained immunohistochemical (IHC) slides from targeted WMH and NAWM samples were digitized and quantified. WMHs and NAWM were associated with inflammation, demyelination, and gliosis. WMHs and NAWM astrocytic changes included decreased AQP1 and AQP4 expression. Abnormal NAWM pathology diminished in severity with increasing distance from WMH.
Subject(s)
Magnetic Resonance Imaging , White Matter , Humans , White Matter/pathology , White Matter/diagnostic imaging , Aged, 80 and over , Female , Male , Brain/pathology , Aquaporins/metabolism , Astrocytes/pathology , Astrocytes/metabolism , Autopsy , Aging/pathology , Aged , Alzheimer Disease/pathology , Alzheimer Disease/metabolismABSTRACT
Platelets are core components of thrombi but their effect on thrombus burden during deep vein thrombosis (DVT) has not been fully characterized. We examined the role of thrombopoietin-altered platelet count on thrombus burden in a murine stasis model of DVT. To modulate platelet count compared to baseline, CD1 mice were pretreated with thrombopoietin antisense oligonucleotide (THPO-ASO, 56% decrease), thrombopoietin mimetic (TPO-mimetic, 36% increase), or saline (within 1%). Thrombi and vein walls were examined on postoperative days (POD) 3 and 7. Thrombus weights on POD 3 were not different between treatment groups (p = .84). The mean thrombus weights on POD 7 were significantly increased in the TPO-mimetic cohort compared to the THPO-ASO (p = .005) and the saline (p = .012) cohorts. Histological grading at POD 3 revealed a significantly increased smooth muscle cell presence in the thrombi and CD31 positive channeling in the vein wall of the TPO-mimetic cohort compared to the saline and THPO-ASO cohorts (p < .05). No differences were observed in histology on POD 7. Thrombopoietin-induced increased platelet count increased thrombus weight on POD 7 indicating platelet count may regulate thrombus burden during early resolution of venous thrombi in this murine stasis model of DVT.
Deep vein thrombosis (DVT) is a pathology in which blood clots form in the deep veins of our body. Usually occurring in the legs, these clots can be dangerous if they dislodge and travel to the heart and are pumped into the lungs. Often these clots do not travel and heal where they formed. However, as the body heals the clot it may also cause damage to the vein wall and predispose the patient to future clots, i.e., the biggest risk factor for a second clot is the first clot. DVT can also cause symptoms of pain, swelling, and redness in the long-term, leading to post-thrombotic syndrome where the initial symptoms of the clot persist for a long time. All blood clots have common components of red blood cells, white blood cells, platelets, and fibrin in varying concentrations. Humans maintain a platelet count between 150 and 400 thousand platelets per microliter of our blood. However, diseases like cancer or medications like chemotherapy can cause a change in our body's platelet count. The effect of a changing platelet count on the size (clot burden) of DVT clot and how platelet count could affect DVT as the clot heals is not fully understood. Studying this might help us develop better targets and treat patients with a wide range of platelet counts who experience DVT. In this study, we intentionally decreased, left unchanged, and increased platelet counts in mice and then created a DVT to study what the effect of low, normal, and high platelet counts, respectively, would be on the clot burden. We observed that mice with higher platelet counts had a higher clot burden during the early part of the healing process of the clot. Within this study, we can conclude that higher platelet counts may lead to higher clot burden in DVT which furthers our understanding of how platelet count affects clot burden during DVT.
Subject(s)
Thrombosis , Venous Thrombosis , Humans , Mice , Animals , Venous Thrombosis/drug therapy , Venous Thrombosis/pathology , Platelet Count , Thrombopoietin/pharmacology , Blood Platelets/pathologyABSTRACT
Alpha-synuclein (aSyn) is a 14 kD protein encoded by the SNCA gene that is expressed in vertebrates and normally localizes to presynaptic terminals and the nucleus. aSyn forms pathological intracellular aggregates that typify a group of important neurodegenerative diseases called synucleinopathies. Previous work in human tissue and model systems indicates that some of these aggregates can be intranuclear, but the significance of aSyn aggregation within the nucleus is not clear. We used a mouse model that develops aggregated aSyn nuclear inclusions. Using aSyn preformed fibril injections in GFP-tagged aSyn transgenic mice, we were able to induce the formation of nuclear aSyn inclusions and study their properties in fixed tissue and in vivo using multiphoton microscopy. In addition, we analyzed human synucleinopathy patient tissue to better understand this pathology. Our data demonstrate that nuclear aSyn inclusions may form through the transmission of aSyn between neurons, and these intranuclear aggregates bear the hallmarks of cytoplasmic Lewy pathology. Neuronal nuclear aSyn inclusions can form rod-like structures that do not contain actin, excluding them from being previously described nuclear actin rods. Longitudinal, in vivo multiphoton imaging indicates that certain morphologies of neuronal nuclear aSyn inclusions predict cell death within 14 days. Human multiple system atrophy cases contain neurons and glia with similar nuclear inclusions, but we were unable to detect such inclusions in Lewy body dementia cases. This study suggests that the dysregulation of a nuclear aSyn function associated with nuclear inclusion formation could play a role in the forms of neurodegeneration associated with synucleinopathy.
Subject(s)
Lewy Body Disease , Multiple System Atrophy , Synucleinopathies , Animals , Mice , Humans , alpha-Synuclein/metabolism , Actins , Multiple System Atrophy/metabolism , Lewy Body Disease/pathology , Disease Models, Animal , Mice, Transgenic , Cell DeathABSTRACT
Ether glycerophospholipids (GPL) are involved in membrane fluidity and fusion. Vinyl-ether GPL are also conjectured to provide antioxidant capacity in the brain. The roles of these lipids in the processes involved in the development of dementia are not understood but choline and ethanolamine vinyl-ether GPL (i.e., plasmalogens) are decreased in the brains of subjects with dementia. In contrast, serine ether and vinyl-ether GPL have not been investigated in human brain. We therefore undertook an evaluation of these lipids, utilizing high-resolution mass spectrometry (HR-MS), in tissues from control and dementia subjects that we had previously characterized in-depth. We can report for the first time that a number of serine ether GPL and a more limited number of serine plasmalogens are present in human frontal cortex. In addition, we found that some of these frontal cortex lipids are decreased in Mild Cognitive Impairment (MCI), early-onset Alzheimer's disease (EOAD), and late-onset AD (LOAD). In contrast no alterations in serine ether GPL were monitored in the frontal cortex of donors with schizophrenia, demonstrating disease specificity. These data suggest that further studies of the roles of ether GPL, including serine ether GPL, in brain function are worthy of undertaking.
ABSTRACT
Human brain lipidomics have elucidated structural lipids and lipid signal transduction pathways in neurologic diseases. Such studies have traditionally sourced tissue exclusively from brain bank biorepositories, however, limited inventories signal that these facilities may not be able to keep pace with this growing research domain. Formalin fixed, whole body donors willed to academic institutions offer a potential supplemental tissue source, the lipid profiles of which have yet to be described. To determine the potential of these subjects in lipid analysis, the lipid levels of fresh and fixed frontal cortical gray matter of human donors were compared using high resolution electrospray ionization mass spectrometry. Results revealed commensurate levels of specific triacylglycerols, diacylglycerols, hexosyl ceramides, and hydroxy hexosyl ceramides. Baseline levels of these lipid families in human fixed tissue were identified via a broader survey study covering six brain regions: cerebellar gray matter, superior cerebellar peduncle, gray and subcortical white matter of the precentral gyrus, periventricular white matter, and internal capsule. Whole body donors may therefore serve as supplemental tissue sources for lipid analysis in a variety of clinical contexts, including Parkinson's disease, Alzheimer's disease, Lewy body dementia, multiple sclerosis, and Gaucher's disease.
ABSTRACT
Sphingolipids constitute a complex class of bioactive lipids with diverse structural and functional roles in neural tissue. Lipidomic techniques continue to provide evidence for their association in neurological diseases, including Parkinson's disease (PD) and Lewy body disease (LBD). However, prior studies have primarily focused on biological tissues outside of the basal ganglia, despite the known relevancy of this brain region in motor and cognitive dysfunction associated with PD and LBD. Therefore electrospray ionization high resolution mass spectrometry was used to analyze levels of sphingolipid species, including ceramides (Cer), dihydroceramides (DHC), hydoxyceramides (OH-Cer), phytoceramides (Phyto-Cer), phosphoethanolamine ceramides (PE-Cer), sphingomyelins (SM), and sulfatides (Sulf) in the caudate, putamen and globus pallidus of PD (n = 7) and LBD (n = 14) human subjects and were compared to healthy controls (n = 9). The most dramatic alterations were seen in the putamen, with depletion of Cer and elevation of Sulf observed in both groups, with additional depletion of OH-Cer and elevation of DHC identified in LBD subjects. Diverging levels of DHC in the caudate suggest differing roles of this lipid in PD and LBD pathogenesis. These sphingolipid alterations in PD and LBD provide evidence for biochemical involvement of the neuronal cell death that characterize these conditions.
ABSTRACT
Primary age-related tauopathy (PART) is a form of Alzheimer-type neurofibrillary degeneration occurring in the absence of amyloid-beta (Aß) plaques. While PART shares some features with Alzheimer disease (AD), such as progressive accumulation of neurofibrillary tangle pathology in the medial temporal lobe and other brain regions, it does not progress extensively to neocortical regions. Given this restricted pathoanatomical pattern and variable symptomatology, there is a need to reexamine and improve upon how PART is neuropathologically assessed and staged. We performed a retrospective autopsy study in a collection (n = 174) of post-mortem PART brains and used logistic regression to determine the extent to which a set of clinical and neuropathological features predict cognitive impairment. We compared Braak staging, which focuses on hierarchical neuroanatomical progression of AD tau and Aß pathology, with quantitative assessments of neurofibrillary burden using computer-derived positive pixel counts on digitized whole slide images of sections stained immunohistochemically with antibodies targeting abnormal hyperphosphorylated tau (p-tau) in the entorhinal region and hippocampus. We also assessed other factors affecting cognition, including aging-related tau astrogliopathy (ARTAG) and atrophy. We found no association between Braak stage and cognitive impairment when controlling for age (p = 0.76). In contrast, p-tau burden was significantly correlated with cognitive impairment even when adjusting for age (p = 0.03). The strongest correlate of cognitive impairment was cerebrovascular disease, a well-known risk factor (p < 0.0001), but other features including ARTAG (p = 0.03) and hippocampal atrophy (p = 0.04) were also associated. In contrast, sex, APOE, psychiatric illness, education, argyrophilic grains, and incidental Lewy bodies were not. These findings support the hypothesis that comorbid pathologies contribute to cognitive impairment in subjects with PART. Quantitative approaches beyond Braak staging are critical for advancing our understanding of the extent to which age-related tauopathy changes impact cognitive function.
Subject(s)
Brain/pathology , Cerebrovascular Disorders/epidemiology , Cognitive Dysfunction/epidemiology , Neurofibrillary Tangles/pathology , Tauopathies/epidemiology , tau Proteins/metabolism , Aged , Aged, 80 and over , Autopsy , Brain/metabolism , Cognitive Dysfunction/metabolism , Cognitive Dysfunction/pathology , Cognitive Dysfunction/psychology , Comorbidity , Female , Humans , Male , Middle Aged , Plaque, Amyloid/pathology , Retrospective Studies , Tauopathies/metabolism , Tauopathies/pathology , Tauopathies/psychology , tau Proteins/geneticsABSTRACT
Early studies in mouse neurodevelopment led to the discovery of the RE1 Silencing Transcription Factor (REST) and its role as a master repressor of neuronal gene expression. Recently, REST was reported to also repress neuronal genes in the human adult brain. These genes were found to be involved in pro-apoptotic pathways; and their repression, associated with increased REST levels during aging, were found to be neuroprotective and conserved across species. However, direct genome-wide REST binding profiles for REST in adult brain have not been identified for any species. Here, we apply this approach to mouse and human hippocampus. We find an expansion of REST binding sites in the human hippocampus that are lacking in both mouse hippocampus and other human non-neuronal cell types. The unique human REST binding sites are associated with genes involved in innate immunity processes and inflammation signaling which, on the basis of histology and recent public transcriptomic analyses, suggest that these new target genes are repressed in glia. We propose that the increases in REST expression in mid-adulthood presage the beginning of brain aging, and that human REST function has evolved to protect the longevity and function of both neurons and glia in human brain.SIGNIFICANCE STATEMENT The RE1 Silencing Transcription Factor (REST) repressor has served historically as a model for gene regulation during mouse neurogenesis. Recent studies of REST have also suggested a conserved role for REST repressor function across lower species during aging. However, direct genome-wide studies for REST have been lacking for human brain. Here, we perform the first genome-wide analysis of REST binding in both human and mouse hippocampus. The majority of REST-occupied genes in human hippocampus are distinct from those in mouse. Further, the REST-associated genes unique to human hippocampus represent a new set related to innate immunity and inflammation, where their gene dysregulation has been implicated in aging-related neuropathology, such as Alzheimer's disease.
Subject(s)
Aging/metabolism , Hippocampus/metabolism , Neuroglia/metabolism , Repressor Proteins/metabolism , Aged , Aging/immunology , Animals , Female , Genome-Wide Association Study , Hippocampus/immunology , Humans , Immunity, Innate/physiology , Male , Mice , Middle Aged , Neuroglia/immunology , Neurons/metabolism , Repressor Proteins/immunologyABSTRACT
Ceramides have been implicated in a number of disease processes. However, current means of evaluation with flow infusion analysis (FIA) have been limited primarily due to poor sensitivity within our high-resolution mass spectrometry lipidomics analytical platform. To circumvent this deficiency, we investigated the potential of chloride adducts as an alternative method to improve sensitivity with electrospray ionization. Chloride adducts of ceramides and ceramide subfamilies provided 2- to 50-fold increases in sensitivity both with analytical standards and biological samples. Chloride adducts of a number of other lipids with reactive hydroxy groups were also enhanced. For example, monogalactosyl diacylglycerols (MGDGs), extracted from frontal lobe cortical gray and subcortical white matter of cognitively intact subjects, were not detected as ammonium adducts but were readily detected as chloride adducts. Hydroxy lipids demonstrate a high level of specificity in that phosphoglycerols and phosphoinositols do not form chloride adducts. In the case of choline glycerophospholipids, the fatty acid substituents of these lipids could be monitored by MS2 of the chloride adducts. Monitoring the chloride adducts of a number of key lipids offers enhanced sensitivity and specificity with FIA. In the case of glycerophosphocholines, the chloride adducts also allow determination of fatty acid substituents. The chloride adducts of lipids possessing electrophilic hydrogens of hydroxyl groups provide significant increases in sensitivity. In the case of glycerophosphocholines, chloride attachment to the quaternary ammonium group generates a dominant anion, which provides the identities of the fatty acid substituents under MS2 conditions.
ABSTRACT
It is necessary to develop an understanding of the specific mechanisms involved in alpha-synuclein aggregation and propagation to develop disease modifying therapies for age-related synucleinopathies, including Parkinson's disease and Dementia with Lewy Bodies. To adequately address this question, we developed a new transgenic mouse model of synucleinopathy that expresses human A53T SynGFP under control of the mouse prion protein promoter. Our characterization of this mouse line demonstrates that it exhibits several distinct advantages over other, currently available, mouse models. This new model allows rigorous study of the initial location of Lewy pathology formation and propagation in the living brain, and strongly suggests that aggregation begins in axonal structures with retrograde propagation to the cell body. This model also shows expeditious development of alpha-synuclein pathology following induction with small, in vitro-generated alpha-synuclein pre-formed fibrils (PFFs), as well as accelerated cell death of inclusion-bearing cells. Using this model, we found that aggregated alpha-synuclein somatic inclusions developed first in neurons, but later showed a second wave of inclusion formation in astrocytes. Interestingly, astrocytes appear to survive much longer after inclusion formation than their neuronal counterparts. This model also allowed careful study of peripheral-to-central spread of Lewy pathology after PFF injection into the hind limb musculature. Our results clearly show evidence of progressive, retrograde trans-synaptic spread of Lewy pathology through known neuroanatomically connected pathways in the motor system. As such, we have developed a promising tool to understand the biology of neurodegeneration associated with alpha-synuclein aggregation and to discover new treatments capable of altering the neurodegenerative disease course of synucleinopathies.
Subject(s)
Brain/pathology , Protein Transport/physiology , Synucleinopathies/pathology , alpha-Synuclein/metabolism , Animals , Astrocytes/pathology , Axons/pathology , Disease Models, Animal , Female , Humans , Lewy Bodies/metabolism , Lewy Bodies/pathology , Male , Mice , Mice, Transgenic , Neurons/pathologyABSTRACT
Pantothenate kinase-associated neurodegeneration (PKAN) is an inborn error of CoA metabolism causing dystonia, parkinsonism, and brain iron accumulation. Lack of a good mammalian model has impeded studies of pathogenesis and development of rational therapeutics. We took a new approach to investigating an existing mouse mutant of Pank2 and found that isolating the disease-vulnerable brain revealed regional perturbations in CoA metabolism, iron homeostasis, and dopamine metabolism and functional defects in complex I and pyruvate dehydrogenase. Feeding mice a CoA pathway intermediate, 4'-phosphopantetheine, normalized levels of the CoA-, iron-, and dopamine-related biomarkers as well as activities of mitochondrial enzymes. Human cell changes also were recovered by 4'-phosphopantetheine. We can mechanistically link a defect in CoA metabolism to these secondary effects via the activation of mitochondrial acyl carrier protein, which is essential to oxidative phosphorylation, iron-sulfur cluster biogenesis, and mitochondrial fatty acid synthesis. We demonstrate the fidelity of our model in recapitulating features of the human disease. Moreover, we identify pharmacodynamic biomarkers, provide insights into disease pathogenesis, and offer evidence for 4'-phosphopantetheine as a candidate therapeutic for PKAN.
Subject(s)
Coenzyme A/metabolism , Dopamine/metabolism , Iron/metabolism , Pantetheine/analogs & derivatives , Pantothenate Kinase-Associated Neurodegeneration/drug therapy , Pantothenate Kinase-Associated Neurodegeneration/metabolism , Animals , Biomarkers/metabolism , Genotype , Mice , Pantetheine/pharmacology , Pantetheine/therapeutic use , Phosphotransferases (Alcohol Group Acceptor)/metabolismABSTRACT
Alpha-synuclein is a presynaptic protein that forms abnormal cytoplasmic aggregates in Lewy body disorders. Although nuclear alpha-synuclein localization has been described, its function in the nucleus is not well understood. We demonstrate that alpha-synuclein modulates DNA repair. First, alpha-synuclein colocalizes with DNA damage response components within discrete foci in human cells and mouse brain. Removal of alpha-synuclein in human cells leads to increased DNA double-strand break (DSB) levels after bleomycin treatment and a reduced ability to repair these DSBs. Similarly, alpha-synuclein knock-out mice show increased neuronal DSBs that can be rescued by transgenic reintroduction of human alpha-synuclein. Alpha-synuclein binds double-stranded DNA and helps to facilitate the non-homologous end-joining reaction. Using a new, in vivo imaging approach that we developed, we find that serine-129-phosphorylated alpha-synuclein is rapidly recruited to DNA damage sites in living mouse cortex. We find that Lewy inclusion-containing neurons in both mouse model and human-derived patient tissue demonstrate increased DSB levels. Based on these data, we propose a model whereby cytoplasmic aggregation of alpha-synuclein reduces its nuclear levels, increases DSBs, and may contribute to programmed cell death via nuclear loss-of-function. This model could inform development of new treatments for Lewy body disorders by targeting alpha-synuclein-mediated DNA repair mechanisms.
Subject(s)
Brain/metabolism , Lewy Body Disease/metabolism , Neurons/metabolism , Parkinson Disease/metabolism , alpha-Synuclein/physiology , Animals , Brain/pathology , Cells, Cultured , DNA Breaks, Double-Stranded , DNA End-Joining Repair , Humans , Lewy Bodies/metabolism , Mice , Mice, Inbred C57BL , Mice, Knockout , Neurons/pathologyABSTRACT
The neurovascular unit, consisting of neurons, astrocytes, and vascular cells, has become the focus of much discussion in the last two decades and emerging literature now suggests an association between neurovascular dysfunction and neurological disorders. In this review, we synthesize the known and suspected contributions of astrocytes to neurovascular dysfunction in disease. Throughout the brain, astrocytes are centrally positioned to dynamically mediate interactions between neurons and the cerebral vasculature, and play key roles in blood-brain barrier maintenance and neurovascular coupling. It is increasingly apparent that the changes in astrocytes in response to a variety of insults to brain tissue -collectively referred to as "reactive astrogliosis" - are not just an epiphenomenon restricted to morphological alterations, but comprise functional changes in astrocytes that contribute to the phenotype of neurological diseases with both beneficial and detrimental effects. In the context of the neurovascular unit, astrocyte dysfunction accompanies, and may contribute to, blood-brain barrier impairment and neurovascular dysregulation, highlighting the need to determine the exact nature of the relationship between astrocyte dysfunction and neurovascular impairments. Targeting astrocytes may represent a new strategy in combinatorial therapeutics for preventing the mismatch of energy supply and demand that often accompanies neurological disorders.
Subject(s)
Astrocytes/metabolism , Brain/metabolism , Gliosis/metabolism , Nervous System Diseases/metabolism , Neurovascular Coupling/physiology , Animals , Astrocytes/pathology , Blood-Brain Barrier/metabolism , Blood-Brain Barrier/pathology , Brain/pathology , Gliosis/pathology , Humans , Nervous System Diseases/pathologyABSTRACT
Our hypothesis is that changes in gene and protein expression are crucial to the development of late-onset Alzheimer’s disease. Previously we examined how DNA alleles control downstream expression of RNA transcripts and how those relationships are changed in late-onset Alzheimer’s disease. We have now examined how proteins are incorporated into networks in two separate series and evaluated our outputs in two different cell lines. Our pipeline included the following steps: (i) predicting expression quantitative trait loci; (ii) determining differential expression; (iii) analysing networks of transcript and peptide relationships; and (iv) validating effects in two separate cell lines. We performed all our analysis in two separate brain series to validate effects. Our two series included 345 samples in the first set (177 controls, 168 cases; age range 65–105; 58% female; KRONOSII cohort) and 409 samples in the replicate set (153 controls, 141 cases, 115 mild cognitive impairment; age range 66–107; 63% female; RUSH cohort). Our top target is heat shock protein family A member 2 (HSPA2), which was identified as a key driver in our two datasets. HSPA2 was validated in two cell lines, with overexpression driving further elevation of amyloid-β40 and amyloid-β42 levels in APP mutant cells, as well as significant elevation of microtubule associated protein tau and phosphorylated-tau in a modified neuroglioma line. This work further demonstrates that studying changes in gene and protein expression is crucial to understanding late onset disease and further nominates HSPA2 as a specific key regulator of late-onset Alzheimer’s disease processes.10.1093/brain/awy215_video1awy215media15824729224001.
Subject(s)
Alzheimer Disease/genetics , Alzheimer Disease/physiopathology , HSP70 Heat-Shock Proteins/physiology , Aged , Aged, 80 and over , Alzheimer Disease/metabolism , Brain/metabolism , Brain Mapping/methods , Cell Line , Female , Gene Expression Profiling/methods , HEK293 Cells , HSP70 Heat-Shock Proteins/genetics , HSP70 Heat-Shock Proteins/metabolism , Humans , Male , Nerve Net/physiopathology , Protein Processing, Post-Translational , RNA/analysis , RNA/metabolism , Transcriptome/geneticsABSTRACT
The deposition of misfolded proteins, including amyloid beta plaques and neurofibrillary tangles is the histopathological hallmark of Alzheimer's disease (AD). The glymphatic system, a brain-wide network of perivascular pathways that supports interstitial solute clearance, is dependent upon expression of the perivascular astroglial water channel aquaporin-4 (AQP4). Impairment of glymphatic function in the aging rodent brain is associated with reduced perivascular AQP4 localization, and in human subjects, reduced perivascular AQP4 localization is associated with AD diagnosis and pathology. Using human transcriptomic data, we demonstrate that expression of perivascular astroglial gene products dystroglycan (DAG1), dystrobrevin (DTNA) and alpha-syntrophin (SNTA1), are associated with dementia status and phosphorylated tau (P-tau) levels in temporal cortex. Gene correlation analysis reveals altered expression of a cluster of potential astrocytic endfoot components in human subjects with dementia, with increased expression associated with temporal cortical P-tau levels. The association between perivascular astroglial gene products, including DTNA and megalencephalic leukoencephalopathy with subcortical cysts 1 (MLC1) with AD status was confirmed in a second human transcriptomic dataset and in human autopsy tissue by Western blot. This suggests changes in the astroglial endfoot domain may underlie vulnerability to protein aggregation in AD.
Subject(s)
Astrocytes/metabolism , Dementia/genetics , Gene Expression Profiling , Gene Expression Regulation , Tauopathies/genetics , Transcriptome , Aged , Aged, 80 and over , Amyloid beta-Peptides/metabolism , Aquaporin 4/genetics , Aquaporin 4/metabolism , Female , Humans , Male , Models, Biological , Organ Specificity/genetics , Parietal Lobe/metabolism , Parietal Lobe/pathologyABSTRACT
Recent reports describing lymphatic vasculature in the meninges have challenged the traditional understanding of interstitial solute clearance from the central nervous system, although the significance of this finding in human neurological disease remains unclear. To begin to define the role of meningeal lymphatic function in the clearance of interstitial amyloid beta (Aß), and the contribution that its failure may make to the development of Alzheimer's disease (AD), we examined meningeal tissue from a case series including AD and control subjects by confocal microscopy. Our findings confirm the presence of lymphatic vasculature in the human meninges and indicate that, unlike perivascular efflux pathways in the brain parenchyma in subjects with AD, Aß is not deposited in or around meningeal lymphatic vessels associated with dural sinuses. Our findings demonstrate that while the meningeal lymphatic vasculature may serve as an efflux route for Aß from the brain and cerebrospinal fluid, Aß does not deposit in the walls of meningeal lymphatic vessels in the setting of AD.
Subject(s)
Alzheimer Disease/metabolism , Amyloid beta-Peptides/metabolism , Glymphatic System/metabolism , Adult , Aged , Aged, 80 and over , Alzheimer Disease/physiopathology , Brain/metabolism , Female , Glymphatic System/physiology , Humans , Lymphatic Vessels/metabolism , Lymphatic Vessels/physiology , Male , Membrane Glycoproteins/metabolism , Meninges/metabolism , Microscopy, Confocal/methods , Middle Aged , Nervous System Diseases/metabolismABSTRACT
High-resolution mass spectrometry provides the resolution required for direct infusion allowing detection and characterization of a vast array of lipids with a single injection. This chapter presents the methodology utilized for both unbiased and targeted lipidomics of cerebrospinal fluid.
Subject(s)
Lipids/cerebrospinal fluid , Mass Spectrometry/methods , Metabolomics , Animals , HumansABSTRACT
BACKGROUND: Research from our laboratory, and that of other investigators, has demonstrated augmented levels of diacylglycerols (DAG) in the frontal cortex and plasma of subjects with Alzheimer's disease (AD) and Mild Cognitive Impairment (MCI). We have extended these observations to investigate the frontal cortex of subjects with Parkinson's disease (PD) and Lewy Body Disease (LBD), with and without coexisting pathologic features of AD. METHODS/PRINCIPAL FINDINGS: Utilizing a high-resolution mass spectrometry analytical platform, we clearly demonstrate that DAG levels are significantly increased in the frontal cortex of subjects with PD, LBD with intermediate neocortical AD neuropathology, and in LBD with established neocortical AD neuropathology. In the case of the PD cohort, increases in cortical DAG levels were detected in cases with no neocortical pathology but were greater in subjects with neocortical pathology. These data suggest that DAG changes occur early in the disease processes and are amplified as cortical dysfunction becomes more established. CONCLUSIONS: These findings suggest that altered DAG synthesis/metabolism is a common feature of neurodegenerative diseases, characterized by proteinopathy, that ultimately result in cognitive deficits. With regard to the mechanism responsible for these biochemical alterations, selective decrements in cortical levels of phosphatidylcholines in LBD and PD suggest that augmented degradation and/or decreased synthesis of these structural glycerophospholipids may contribute to increases in the pool size of free DAGs. The observed augmentation of DAG levels may be phospholipase-driven since neuroinflammation is a consistent feature of all disease cohorts. If this conclusion can be validated it would support utilizing DAG levels as a biomarker of the early disease process and the investigation of early intervention with anti-inflammatory agents.
Subject(s)
Diglycerides/metabolism , Frontal Lobe/metabolism , Lewy Body Disease/metabolism , Parkinson Disease/metabolism , Aged , Aged, 80 and over , Alzheimer Disease/blood , Alzheimer Disease/metabolism , Biomarkers/blood , Biomarkers/metabolism , Diglycerides/blood , Female , Frontal Lobe/pathology , Humans , Lewy Body Disease/blood , Male , Middle Aged , Neocortex/metabolism , Neocortex/pathology , Neurodegenerative Diseases/blood , Neurodegenerative Diseases/metabolism , Parkinson Disease/bloodABSTRACT
Cognitive decline is a devastating clinical condition, heavily correlated with age progression. In the cases of Alzheimer's disease, Parkinson's disease, and Lewy body disease, the common neuropathologies are proteinopathies and neuroinflammation. Herein, we review current lipidomics findings and conclude that brain and circulating diacylglycerols represent biomarkers of this ongoing sustained immune response, presumably involving microglia. We further hypothesize that a logical next step will be to evaluate biomarkers of immune activation in a cohort of patients with Mild Cognitive Impairment (MCI) and subsequently attempt to provide therapeutic intervention with anti-inflammatory therapy in MCI patients with immune activation. Although this is an urgent and theoretically safe therapeutic trial, it will likely necessitate government support.
Subject(s)
Dementia/immunology , Dementia/metabolism , Diglycerides/immunology , Proteins/metabolism , Anti-Inflammatory Agents/therapeutic use , Biomarkers/blood , Cognitive Dysfunction/blood , Cognitive Dysfunction/drug therapy , Cognitive Dysfunction/immunology , Cohort Studies , Dementia/blood , Dementia/pathology , Diglycerides/blood , HumansABSTRACT
Coenzyme A is an essential metabolite known for its central role in over one hundred cellular metabolic reactions. In cells, Coenzyme A is synthesized de novo in five enzymatic steps with vitamin B5 as the starting metabolite, phosphorylated by pantothenate kinase. Mutations in the pantothenate kinase 2 gene cause a severe form of neurodegeneration for which no treatment is available. One therapeutic strategy is to generate Coenzyme A precursors downstream of the defective step in the pathway. Here we describe the synthesis, characteristics and in vivo rescue potential of the acetyl-Coenzyme A precursor S-acetyl-4'-phosphopantetheine as a possible treatment for neurodegeneration associated with pantothenate kinase deficiency.