RESUMO
White matter abnormalities, related to poor cerebral perfusion, are a core feature of small vessel cerebrovascular disease, and critical determinants of vascular cognitive impairment and dementia. Despite this importance there is a lack of treatment options. Proliferation of microglia producing an expanded, reactive population and associated neuroinflammatory alterations have been implicated in the onset and progression of cerebrovascular white matter disease, in patients and in animal models, suggesting that targeting microglial proliferation may exert protection. Colony-stimulating factor-1 receptor (CSF1R) is a key regulator of microglial proliferation. We found that the expression of CSF1R/Csf1r and other markers indicative of increased microglial abundance are significantly elevated in damaged white matter in human cerebrovascular disease and in a clinically relevant mouse model of chronic cerebral hypoperfusion and vascular cognitive impairment. Using the mouse model, we investigated long-term pharmacological CSF1R inhibition, via GW2580, and demonstrated that the expansion of microglial numbers in chronic hypoperfused white matter is prevented. Transcriptomic analysis of hypoperfused white matter tissue showed enrichment of microglial and inflammatory gene sets, including phagocytic genes that were the predominant expression modules modified by CSF1R inhibition. Further, CSF1R inhibition attenuated hypoperfusion-induced white matter pathology and rescued spatial learning impairments and to a lesser extent cognitive flexibility. Overall, this work suggests that inhibition of CSF1R and microglial proliferation mediates protection against chronic cerebrovascular white matter pathology and cognitive deficits. Our study nominates CSF1R as a target for the treatment of vascular cognitive disorders with broader implications for treatment of other chronic white matter diseases.
Assuntos
Transtornos Cerebrovasculares , Transtornos Cognitivos , Disfunção Cognitiva , Leucoencefalopatias , Receptores de Fator Estimulador das Colônias de Granulócitos e Macrófagos , Substância Branca , Animais , Camundongos , Transtornos Cerebrovasculares/metabolismo , Transtornos Cerebrovasculares/patologia , Transtornos Cognitivos/etiologia , Transtornos Cognitivos/patologia , Disfunção Cognitiva/metabolismo , Modelos Animais de Doenças , Leucoencefalopatias/genética , Leucoencefalopatias/metabolismo , Camundongos Endogâmicos C57BL , Microglia/metabolismo , Receptores de Fator Estimulador de Colônias/metabolismo , Substância Branca/patologia , Receptores de Fator Estimulador das Colônias de Granulócitos e Macrófagos/antagonistas & inibidores , Receptores de Fator Estimulador das Colônias de Granulócitos e Macrófagos/metabolismoRESUMO
BACKGROUND: Considerable evidence links dietary salt intake with the development of hypertension, left ventricular hypertrophy, and increased risk of stroke and coronary heart disease. Despite extensive epidemiological and basic science interrogation of the relationship between high salt (HS) intake and blood pressure, it remains unclear how HS impacts endothelial cell (EC) and vascular structure in vivo. This study aims to elucidate HS-induced vascular pathology using a differential systemic decellularization in vivo approach. METHODS: We performed systematic molecular characterization of the endothelial glycocalyx and EC proteomes in mice with HS (8%) diet-induced hypertension versus healthy control animals. Isolation of eGC and EC compartments was achieved using differential systemic decellularization in vivo methodology. Altered protein expression in hypertensive compared to normal mice was characterized by liquid chromatography tandem mass spectrometry. Proteomic results were validated using functional assays, microscopic imaging, and histopathologic evaluation. RESULTS: Proteomic analysis revealed a significant downregulation of eGC and associated proteins in HS diet-induced hypertensive mice (among 1696 proteins identified in this group, 723 were markedly decreased in abundance, while only 168 were increased in abundance. Bioinformatic analysis indicated substantial derangement of the eGC layer, which was subsequently confirmed by fluorescent and electron microscopy assessment of vessel damage ex vivo. In the EC fraction, HS-induced hypertension significantly altered protein mediators of contractility, metabolism, mechanotransduction, renal function, and the coagulation cascade. In particular, we observed dysregulation of integrin subunits α2, α2b, and α5, which was associated with arterial wall inflammation and substantial infiltration of CD68+ monocyte-macrophages. Consequently, HS-induced hypertensive mice also displayed reduced vascular integrity of multiple organs including lungs, kidneys, and heart. CONCLUSIONS: These findings provide novel molecular insight into HS-induced structural changes in eGC and EC composition that may increase cardiovascular risk and potentially guide the development of new diagnostics and therapeutic interventions.
Assuntos
Hipertensão , Cloreto de Sódio na Dieta , Camundongos , Animais , Cloreto de Sódio na Dieta/efeitos adversos , Proteômica , Mecanotransdução Celular , Pressão Sanguínea/fisiologiaRESUMO
Two of every three persons living with dementia reside in low- and middle-income countries (LMICs). The projected increase in global dementia rates is expected to affect LMICs disproportionately. However, the majority of global dementia care costs occur in high-income countries (HICs), with dementia research predominantly focusing on HICs. This imbalance necessitates LMIC-focused research to ensure that characterization of dementia accurately reflects the involvement and specificities of diverse populations. Development of effective preventive, diagnostic, and therapeutic approaches for dementia in LMICs requires targeted, personalized, and harmonized efforts. Our article represents timely discussions at the 2022 Symposium on Dementia and Brain Aging in LMICs that identified the foremost opportunities to advance dementia research, differential diagnosis, use of neuropsychometric tools, awareness, and treatment options. We highlight key topics discussed at the meeting and provide future recommendations to foster a more equitable landscape for dementia prevention, diagnosis, care, policy, and management in LMICs. HIGHLIGHTS: Two-thirds of persons with dementia live in LMICs, yet research and costs are skewed toward HICs. LMICs expect dementia prevalence to more than double, accompanied by socioeconomic disparities. The 2022 Symposium on Dementia in LMICs addressed advances in research, diagnosis, prevention, and policy. The Nairobi Declaration urges global action to enhance dementia outcomes in LMICs.
Assuntos
Envelhecimento , Demência , Países em Desenvolvimento , Humanos , Demência/diagnóstico , Demência/terapia , Demência/epidemiologia , Encéfalo , Congressos como Assunto , Pesquisa BiomédicaRESUMO
BACKGROUND: The African Stroke Organization (ASO) in partnership with the University of Central Lancashire's Stroke Research Team launched the Africa-UK Stroke Partnership (AUKSP). AUKSP undertook two (stroke expert and hospital Stroke Unit (SU)) on-line surveys mapping existing capacity and capability to deliver African stroke care. METHODS: An on-line expert survey tool was sent to 139 stroke experts in 54 African countries October 2021-March 2022 and the hospital SU survey to 120 hospital SUs (identified from the expert survey) June-October 2022. Both survey tools were prepared according to the World Stroke Organisation's Roadmap for Delivering Quality Stroke Care. Completed responses were exported from Qualtrics into Microsoft excel and were analysed descriptively. RESULTS: Forty-five expert responses and 62 hospital SU responses were analysed, representing 54(87%) public hospitals, 7(11%) private and 1(2%) charitable organization. In both surveys, three main priorities for improvement of stroke services were: a rapid and prompt stroke diagnosis; effective primary and secondary stroke prevention, and acute stroke management. Survey findings suggest that there is a low presence of national stroke surveillance systems and registries, and heterogeneity in availability of diagnostic services, SUs, endovascular treatments, and rehabilitation. CONCLUSION: Significant gaps exist in Africa's capacity and capability to deliver essential elements of effective and quality stroke care. Tackling these challenges requires urgent and sustained multi-stakeholder action including: government, administrators, policy makers and other partners. Our survey findings highlight key priority areas for multi-stakeholder engagement and crafting of a pragmatic, prioritized and context-sensitive African Stroke Action Plan.
RESUMO
Cerebral microvascular disease (MVD) is an important cause of vascular cognitive impairment. MVD is heterogeneous in aetiology, ranging from universal ageing to the sporadic (hypertension, sporadic cerebral amyloid angiopathy [CAA] and chronic kidney disease) and the genetic (e.g., familial CAA, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy [CADASIL] and cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy [CARASIL]). The brain parenchymal consequences of MVD predominantly consist of lacunar infarcts (lacunes), microinfarcts, white matter disease of ageing and microhaemorrhages. MVD is characterised by substantial arteriolar neuropathology involving ubiquitous vascular smooth muscle cell (SMC) abnormalities. Cerebral MVD is characterised by a wide variety of arteriolar injuries but only a limited number of parenchymal manifestations. We reason that the cerebral arteriole plays a dominant role in the pathogenesis of each type of MVD. Perturbations in signalling and function (i.e., changes in proliferation, apoptosis, phenotypic switch and migration of SMC) are prominent in the pathogenesis of cerebral MVD, making 'cerebral angiomyopathy' an appropriate term to describe the spectrum of pathologic abnormalities. The evidence suggests that the cerebral arteriole acts as both source and mediator of parenchymal injury in MVD.
Assuntos
CADASIL , Angiopatia Amiloide Cerebral , Doenças Neuromusculares , Humanos , Arteríolas/metabolismo , Arteríolas/patologia , Infarto Cerebral/genética , Infarto Cerebral/patologia , CADASIL/patologia , Encéfalo/patologia , Angiopatia Amiloide Cerebral/patologia , Doenças Neuromusculares/patologiaRESUMO
Disturbances in the brain's capacity to meet its energy demand increase the risk of synaptic loss, neurodegeneration, and cognitive decline. Nutritional and metabolic interventions that target metabolic pathways combined with diagnostics to identify deficits in cerebral bioenergetics may therefore offer novel therapeutic potential for Alzheimer's disease (AD) prevention and management. Many diet-derived natural bioactive components can govern cellular energy metabolism but their effects on brain aging are not clear. This review examines how nutritional metabolism can regulate brain bioenergetics and mitigate AD risk. We focus on leading mechanisms of cerebral bioenergetic breakdown in the aging brain at the cellular level, as well as the putative causes and consequences of disturbed bioenergetics, particularly at the blood-brain barrier with implications for nutrient brain delivery and nutritional interventions. Novel therapeutic nutrition approaches including diet patterns are provided, integrating studies of the gut microbiome, neuroimaging, and other biomarkers to guide future personalized nutritional interventions.
RESUMO
This is an exciting time for scientific discovery that aims to reduce the frequency and impact of neurological, mental health and substance-use disorders. As it became increasingly clear that low- and middle-income countries have a disproportionate share of these disorders, and that many of the problems are best addressed by indigenous researchers who can seek context-sensitive solutions, the US National Institutes of Health and other research funders began to invest more in low- and middle-income country-focused research and research capacity-building to confront this significant public health challenge. In an effort to identify existing information, knowledge gaps, and emerging research and research capacity-building opportunities that are particularly relevant to low- and middle-income countries, in February 2014 the Center for Global Health Studies at the National Institutes of Health Fogarty International Center held a workshop to explore these issues with scientific experts from low- and middle-income countries and the United States. This evolved into the preparation of the Reviews in this supplement, which is designed to highlight opportunities and challenges associated with topical areas in brain-disorders research over the coming decade. This Introduction highlights some of the over-arching and intersecting priorities for addressing causes, prevention, treatment and rehabilitation as well as best practices to promote overall nervous system health. We review some brain disorders in low- and middle-income countries, while the Reviews describe relevant issues and the epidemiology of particular conditions in greater depth.
Assuntos
Envelhecimento , Cooperação Internacional , Doenças do Sistema Nervoso , Adulto , Pesquisa Biomédica/economia , Pesquisa Biomédica/organização & administração , Encefalopatias/economia , Encefalopatias/epidemiologia , Criança , Efeitos Psicossociais da Doença , Países em Desenvolvimento/economia , Países em Desenvolvimento/estatística & dados numéricos , Humanos , National Institutes of Health (U.S.)/organização & administração , Doenças do Sistema Nervoso/economia , Doenças do Sistema Nervoso/epidemiologia , Apoio à Pesquisa como Assunto , Transtornos Relacionados ao Uso de Substâncias/economia , Transtornos Relacionados ao Uso de Substâncias/epidemiologia , Estados UnidosRESUMO
Proper functioning of the brain is dependent on integrity of the cerebral vasculature. During ageing, a number of factors including aortic or arterial stiffness, autonomic dysregulation, neurovascular uncoupling and blood-brain barrier (BBB) damage will define the dynamics of brain blood flow and local perfusion. The nature and extent of ageing-related cerebrovascular changes, the degree of involvement of the heart and extracranial vessels and the consequent location of tissue pathology may vary considerably. Atheromatous disease retarding flow is a common vascular insult, which increases exponentially with increasing age. Arteriolosclerosis characterized as a prominent feature of small vessel disease is one of the first changes to occur during the natural history of cerebrovascular pathology. At the capillary level, the cerebral endothelium, which forms the BBB undergoes changes including reduced cytoplasm, fewer mitochondria, loss of tight junctions and thickened basement membranes with collagenosis. Astrocyte end-feet protecting the BBB retract as part of the clasmatodendrotic response whereas pericyte coverage is altered. The consequences of these microvascular changes are lacunar infarcts, cortical and subcortical microinfarcts, microbleeds and diffuse white matter disease, which involves myelin loss and axonal abnormalities. The deeper structures are particularly vulnerable because of the relatively reduced density of the microvascular network formed by perforating and penetrating end arteries. Ultimately, the integrity of both the neurovascular and gliovascular units is compromised such that there is an overall synergistic effect reflecting on ageing associated cerebral perfusion and permeability. More than one protagonist appears to be involved in ageing-related cognitive dysfunction characteristically associated with the neurocognitive disorders.
Assuntos
Envelhecimento/patologia , Encéfalo/irrigação sanguínea , Transtornos Neurocognitivos/patologia , Barreira Hematoencefálica/metabolismo , HumanosRESUMO
Advances in neuroimaging have enabled greater understanding of the progression of cerebral degenerative processes associated with ageing-related dementias. Leukoaraiosis or rarefied white matter (WM) originally described on computed tomography is one of the most prominent changes which occurs in older age. White matter hyperintensities (WMH) evident on magnetic resonance imaging have become commonplace to describe WM changes in relation to cognitive dysfunction, types of stroke injury, cerebral small vessel disease and neurodegenerative disorders including Alzheimer's disease. Substrates of WM degeneration collectively include myelin loss, axonal abnormalities, arteriolosclerosis and parenchymal changes resulting from lacunar infarcts, microinfarcts, microbleeds and perivascular spacing. WM cells incorporating astrocytes, oligodendrocytes, pericytes and microglia are recognized as key cellular components of the gliovascular unit. They respond to ongoing pathological processes in different ways leading to disruption of the gliovascular unit. The most robust alterations involve oligodendrocyte loss and astrocytic clasmatodendrosis with displacement of the water channel protein, aquaporin 4. These modifications likely precede arteriolosclerosis and capillary degeneration and involve tissue oedema, breach of the blood-brain barrier and induction of a chronic hypoxic state in the deep WM. Several pathophysiological mechanisms are proposed to explain how WM changes commencing with haemodynamic changes within the vascular system impact on cognitive dysfunction. Animal models simulating cerebral hypoperfusion in man have paved the way for several translational opportunities. Various compounds with variable efficacies have been tested to reduce oxidative stress, inflammation and blood-brain barrier damage in the WM. Our review demonstrates that WM degeneration encompasses multiple substrates and therefore more than one pharmacological approach is necessary to preserve axonal function and prevent cognitive impairment. This article is part of the Special Issue "Vascular Dementia".
Assuntos
Envelhecimento , Encéfalo/patologia , Demência Vascular/patologia , Demência/patologia , Leucoaraiose/complicações , Substância Branca/patologia , Animais , Barreira Hematoencefálica/patologia , Encéfalo/fisiopatologia , Demência/etiologia , Demência/fisiopatologia , Demência Vascular/etiologia , Demência Vascular/fisiopatologia , Humanos , Leucoaraiose/diagnóstico por imagem , Bainha de Mielina/patologia , Neuroglia/patologia , Neurônios/patologia , Substância Branca/fisiopatologiaRESUMO
The global burden of ischaemic strokes is almost 4-fold greater than haemorrhagic strokes. Current evidence suggests that 25-30% of ischaemic stroke survivors develop immediate or delayed vascular cognitive impairment (VCI) or vascular dementia (VaD). Dementia after stroke injury may encompass all types of cognitive disorders. States of cognitive dysfunction before the index stroke are described under the umbrella of pre-stroke dementia, which may entail vascular changes as well as insidious neurodegenerative processes. Risk factors for cognitive impairment and dementia after stroke are multifactorial including older age, family history, genetic variants, low educational status, vascular comorbidities, prior transient ischaemic attack or recurrent stroke and depressive illness. Neuroimaging determinants of dementia after stroke comprise silent brain infarcts, white matter changes, lacunar infarcts and medial temporal lobe atrophy. Until recently, the neuropathology of dementia after stroke was poorly defined. Most of post-stroke dementia is consistent with VaD involving multiple substrates. Microinfarction, microvascular changes related to blood-brain barrier damage, focal neuronal atrophy and low burden of co-existing neurodegenerative pathology appear key substrates of dementia after stroke injury. The elucidation of mechanisms of dementia after stroke injury will enable establishment of effective strategy for symptomatic relief and prevention. Controlling vascular disease risk factors is essential to reduce the burden of cognitive dysfunction after stroke. This article is part of a Special Issue entitled: Vascular Contributions to Cognitive Impairment and Dementia edited by M. Paul Murphy, Roderick A. Corriveau and Donna M. Wilcock.
Assuntos
Encéfalo/patologia , Disfunção Cognitiva/etiologia , Disfunção Cognitiva/patologia , Demência Vascular/etiologia , Demência Vascular/patologia , Acidente Vascular Cerebral/complicações , Animais , Atrofia/patologia , Disfunção Cognitiva/diagnóstico , Demência Vascular/diagnóstico , Humanos , Neuroimagem , Fatores de Risco , Acidente Vascular Cerebral/diagnóstico , Acidente Vascular Cerebral/patologia , Substância Branca/patologiaRESUMO
BACKGROUND: Disease models are useful for prospective studies of pathology, identification of molecular and cellular mechanisms, pre-clinical testing of interventions, and validation of clinical biomarkers. Here, we review animal models relevant to vascular cognitive impairment (VCI). A synopsis of each model was initially presented by expert practitioners. Synopses were refined by the authors, and subsequently by the scientific committee of a recent conference (International Conference on Vascular Dementia 2015). Only peer-reviewed sources were cited. METHODS: We included models that mimic VCI-related brain lesions (white matter hypoperfusion injury, focal ischaemia, cerebral amyloid angiopathy) or reproduce VCI risk factors (old age, hypertension, hyperhomocysteinemia, high-salt/high-fat diet) or reproduce genetic causes of VCI (CADASIL-causing Notch3 mutations). CONCLUSIONS: We concluded that (1) translational models may reflect a VCI-relevant pathological process, while not fully replicating a human disease spectrum; (2) rodent models of VCI are limited by paucity of white matter; and (3) further translational models, and improved cognitive testing instruments, are required.
Assuntos
Demência Vascular/patologia , Modelos Animais de Doenças , Animais , Encéfalo/patologia , Demência Vascular/genética , Fatores de RiscoRESUMO
BACKGROUND: This study was designed to explore the beneficial effects of environmental enrichment (EE) on white matter glial changes in a mouse model of chronic cerebral hypoperfusion induced by bilateral common carotid artery stenosis (BCAS). METHODS: A total of 74 wild-type male C57BL/6J mice underwent BCAS or sham surgery. One week after surgery, the mice were randomly assigned into three different groups having varied amounts of EE-standard housing with no EE conditions (std), limited exposure with 3 h EE a day (3 h) and full-time exposure to EE (full) for 12 weeks. At 16 weeks after BCAS surgery, behavioural and cognitive function were assessed prior to euthanasia. Brain tissues were analysed for the degree of gliosis including morphological changes in astrocytes and microglia. RESULTS: Chronic cerebral hypoperfusion (or BCAS) increased clasmatodendrocytes (damaged astrocytes) with disruption of aquaporin-4 immunoreactivity and an increased degree of microglial activation/proliferation. BCAS also impaired behavioural and cognitive function. These changes were significantly attenuated, by limited exposure compared to full-time exposure to EE. CONCLUSIONS: Our results suggest that moderate or limited exposure to EE substantially reduced glial damage/activation. Our findings also suggest moderate rather than continuous exposure to EE is beneficial for patients with subcortical ischaemic vascular dementia characterised by white matter disease-related inflammation.
Assuntos
Estenose das Carótidas/complicações , Estenose das Carótidas/patologia , Meio Ambiente , Leucoencefalopatias/patologia , Neuroglia/metabolismo , Análise de Variância , Animais , Aquaporina 4/metabolismo , Proteínas de Ligação ao Cálcio/metabolismo , Proliferação de Células , Modelos Animais de Doenças , Proteína Glial Fibrilar Ácida/metabolismo , Gliose/etiologia , Gliose/patologia , Leucoencefalopatias/etiologia , Leucoencefalopatias/enfermagem , Masculino , Aprendizagem em Labirinto , Camundongos , Camundongos Endogâmicos C57BL , Proteínas dos Microfilamentos/metabolismo , Comportamento de Nidação/fisiologia , Fatores de TempoRESUMO
Increasing evidence suggests that vascular risk factors contribute to neurodegeneration, cognitive impairment and dementia. While there is considerable overlap between features of vascular cognitive impairment and dementia (VCID) and Alzheimer's disease (AD), it appears that cerebral hypoperfusion is the common underlying pathophysiological mechanism which is a major contributor to cognitive decline and degenerative processes leading to dementia. Sustained cerebral hypoperfusion is suggested to be the cause of white matter attenuation, a key feature common to both AD and dementia associated with cerebral small vessel disease (SVD). White matter changes increase the risk for stroke, dementia and disability. A major gap has been the lack of mechanistic insights into the evolution and progress of VCID. However, this gap is closing with the recent refinement of rodent models which replicate chronic cerebral hypoperfusion. In this review, we discuss the relevance and advantages of these models in elucidating the pathogenesis of VCID and explore the interplay between hypoperfusion and the deposition of amyloid ß (Aß) protein, as it relates to AD. We use examples of our recent investigations to illustrate the utility of the model in preclinical testing of candidate drugs and lifestyle factors. We propose that the use of such models is necessary for tackling the urgently needed translational gap from preclinical models to clinical treatments.
Assuntos
Comportamento Animal , Circulação Cerebrovascular , Transtornos Cerebrovasculares/complicações , Transtornos Cognitivos/etiologia , Cognição , Demência Vascular/etiologia , Pesquisa Translacional Biomédica/métodos , Peptídeos beta-Amiloides , Animais , Comportamento Animal/efeitos dos fármacos , Encéfalo/metabolismo , Encéfalo/patologia , Encéfalo/fisiopatologia , Transtornos Cerebrovasculares/tratamento farmacológico , Transtornos Cerebrovasculares/fisiopatologia , Transtornos Cerebrovasculares/psicologia , Doença Crônica , Cognição/efeitos dos fármacos , Transtornos Cognitivos/tratamento farmacológico , Transtornos Cognitivos/fisiopatologia , Transtornos Cognitivos/psicologia , Demência Vascular/tratamento farmacológico , Demência Vascular/fisiopatologia , Demência Vascular/psicologia , Modelos Animais de Doenças , Progressão da Doença , Humanos , Leucoencefalopatias/etiologia , Leucoencefalopatias/fisiopatologia , Leucoencefalopatias/psicologia , Placa Amiloide , Fatores de Risco , Especificidade da Espécie , Fatores de TempoRESUMO
White matter hyperintensities as seen on brain T2-weighted magnetic resonance imaging are associated with varying degrees of cognitive dysfunction in stroke, cerebral small vessel disease and dementia. The pathophysiological mechanisms within the white matter accounting for cognitive dysfunction remain unclear. With the hypothesis that gliovascular interactions are impaired in subjects with high burdens of white matter hyperintensities, we performed clinicopathological studies in post-stroke survivors, who had exhibited greater frontal white matter hyperintensities volumes that predicted shorter time to dementia onset. Histopathological methods were used to identify substrates in the white matter that would distinguish post-stroke demented from post-stroke non-demented subjects. We focused on the reactive cell marker glial fibrillary acidic protein (GFAP) to study the incidence and location of clasmatodendrosis, a morphological attribute of irreversibly injured astrocytes. In contrast to normal appearing GFAP+ astrocytes, clasmatodendrocytes were swollen and had vacuolated cell bodies. Other markers such as aldehyde dehydrogenase 1 family, member L1 (ALDH1L1) showed cytoplasmic disintegration of the astrocytes. Total GFAP+ cells in both the frontal and temporal white matter were not greater in post-stroke demented versus post-stroke non-demented subjects. However, the percentage of clasmatodendrocytes was increased by >2-fold in subjects with post-stroke demented compared to post-stroke non-demented subjects (P = 0.026) and by 11-fold in older controls versus young controls (P < 0.023) in the frontal white matter. High ratios of clasmotodendrocytes to total astrocytes in the frontal white matter were consistent with lower Mini-Mental State Examination and the revised Cambridge Cognition Examination scores in post-stroke demented subjects. Double immunofluorescent staining showed aberrant co-localization of aquaporin 4 (AQP4) in retracted GFAP+ astrocytes with disrupted end-feet juxtaposed to microvessels. To explore whether this was associated with the disrupted gliovascular interactions or blood-brain barrier damage, we assessed the co-localization of GFAP and AQP4 immunoreactivities in post-mortem brains from adult baboons with cerebral hypoperfusive injury, induced by occlusion of three major vessels supplying blood to the brain. Analysis of the frontal white matter in perfused brains from the animals surviving 1-28 days after occlusion revealed that the highest intensity of fibrinogen immunoreactivity was at 14 days. At this survival time point, we also noted strikingly similar redistribution of AQP4 and GFAP+ astrocytes transformed into clasmatodendrocytes. Our findings suggest novel associations between irreversible astrocyte injury and disruption of gliovascular interactions at the blood-brain barrier in the frontal white matter and cognitive impairment in elderly post-stroke survivors. We propose that clasmatodendrosis is another pathological substrate, linked to white matter hyperintensities and frontal white matter changes, which may contribute to post-stroke or small vessel disease dementia.
Assuntos
Envelhecimento/patologia , Astrócitos/patologia , Demência/complicações , Demência/patologia , Acidente Vascular Cerebral/complicações , Substância Branca/patologia , Idoso , Idoso de 80 Anos ou mais , Aldeído Desidrogenase/metabolismo , Animais , Aquaporina 4/metabolismo , Astrócitos/metabolismo , Barreira Hematoencefálica/patologia , Estudos de Casos e Controles , Transtornos Cognitivos/patologia , Feminino , Lobo Frontal/irrigação sanguínea , Lobo Frontal/patologia , Proteína Glial Fibrilar Ácida/metabolismo , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Neuroimagem , Testes Neuropsicológicos , Oxirredutases atuantes sobre Doadores de Grupo CH-NH , Papio anubis , Acidente Vascular Cerebral/patologia , Substância Branca/irrigação sanguíneaRESUMO
BACKGROUND: Cerebrovascular lesions are a frequent finding in the elderly population. However, the impact of these lesions on cognitive performance, the prevalence of vascular dementia, and the pathophysiology behind characteristic in vivo imaging findings are subject to controversy. Moreover, there are no standardised criteria for the neuropathological assessment of cerebrovascular disease or its related lesions in human post-mortem brains, and conventional histological techniques may indeed be insufficient to fully reflect the consequences of cerebrovascular disease. DISCUSSION: Here, we review and discuss both the neuropathological and in vivo imaging characteristics of cerebrovascular disease, prevalence rates of vascular dementia, and clinico-pathological correlations. We also discuss the frequent comorbidity of cerebrovascular pathology and Alzheimer's disease pathology, as well as the difficult and controversial issue of clinically differentiating between Alzheimer's disease, vascular dementia and mixed Alzheimer's disease/vascular dementia. Finally, we consider additional novel approaches to complement and enhance current post-mortem assessment of cerebral human tissue. CONCLUSION: Elucidation of the pathophysiology of cerebrovascular disease, clarification of characteristic findings of in vivo imaging and knowledge about the impact of combined pathologies are needed to improve the diagnostic accuracy of clinical diagnoses.
Assuntos
Encéfalo/patologia , Demência Vascular/patologia , Idoso , Doença de Alzheimer/epidemiologia , Doença de Alzheimer/patologia , Autopsia , Transtornos Cerebrovasculares/epidemiologia , Transtornos Cerebrovasculares/patologia , Comorbidade , Demência/epidemiologia , Demência/patologia , Demência Vascular/epidemiologia , Humanos , PrevalênciaRESUMO
AIM: Brain clusterin is known to be associated with the amyloid-ß deposits in Alzheimer's disease (AD). We assessed the distribution of clusterin immunoreactivity in cerebrovascular disorders, particularly focusing on white matter changes in small vessel diseases. METHODS: Post-mortem brain tissues from the frontal or temporal lobes of a total of 70 subjects with various disorders including cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), cerebral amyloid angiopathy (CAA) and AD were examined using immunohistochemistry and immunofluorescence. We further used immunogold electron microscopy to study clusterin immunoreactivity in extracellular deposits in CADASIL. RESULTS: Immunostaining with clusterin antibodies revealed strong localization in arterioles and capillaries, besides cortical neurones. We found that clusterin immunostaining was significantly increased in the frontal white matter of CADASIL and pontine autosomal dominant microangiopathy and leukoencephalopathy subjects. In addition, clusterin immunostaining correlated with white matter pathology severity scores. Immunostaining in axons ranged from fine punctate deposits in single axons to larger confluent areas with numerous swollen axon bulbs, similar to that observed with known axon damage markers such as non-phosphorylated neurofilament H and the amyloid precursor protein. Immunofluorescence and immunogold electron microscopy experiments showed that whereas clusterin immunoreactivity was closely associated with vascular amyloid-ß in CAA, it was lacking within the granular osmiophilic material immunolabelled by NOTCH3 extracelluar domain aggregates found in CADASIL. CONCLUSIONS: Our results suggest a wider role for clusterin associated with white matter damage in addition to its ability to chaperone proteins for clearance via the perivascular drainage pathways in several disease states.
Assuntos
Doenças de Pequenos Vasos Cerebrais/metabolismo , Doenças de Pequenos Vasos Cerebrais/patologia , Clusterina/metabolismo , Substância Branca/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Autopsia , Encéfalo/metabolismo , Encéfalo/patologia , Clusterina/análise , Feminino , Imunofluorescência , Humanos , Imuno-Histoquímica , Masculino , Pessoa de Meia-Idade , Substância Branca/metabolismoRESUMO
Vascular dementia (VaD) is recognised as a neurocognitive disorder, which is explained by numerous vascular causes in the general absence of other pathologies. The heterogeneity of cerebrovascular disease makes it challenging to elucidate the neuropathological substrates and mechanisms of VaD as well as vascular cognitive impairment (VCI). Consensus and accurate diagnosis of VaD relies on wide-ranging clinical, neuropsychometric and neuroimaging measures with subsequent pathological confirmation. Pathological diagnosis of suspected clinical VaD requires adequate postmortem brain sampling and rigorous assessment methods to identify important substrates. Factors that define the subtypes of VaD include the nature and extent of vascular pathologies, degree of involvement of extra and intracranial vessels and the anatomical location of tissue changes. Atherosclerotic and cardioembolic diseases appear the most common substrates of vascular brain injury or infarction. Small vessel disease characterised by arteriolosclerosis and lacunar infarcts also causes cortical and subcortical microinfarcts, which appear to be the most robust substrates of cognitive impairment. Diffuse WM changes with loss of myelin and axonal abnormalities are common to almost all subtypes of VaD. Medial temporal lobe and hippocampal atrophy accompanied by variable hippocampal sclerosis are also features of VaD as they are of Alzheimer's disease. Recent observations suggest that there is a vascular basis for neuronal atrophy in both the temporal and frontal lobes in VaD that is entirely independent of any Alzheimer pathology. Further knowledge on specific neuronal and dendro-synaptic changes in key regions resulting in executive dysfunction and other cognitive deficits, which define VCI and VaD, needs to be gathered. Hereditary arteriopathies such as cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy or CADASIL have provided insights into the mechanisms of dementia associated with cerebral small vessel disease. Greater understanding of the neurochemical and molecular investigations is needed to better define microvascular disease and vascular substrates of dementia. The investigation of relevant animal models would be valuable in exploring the pathogenesis as well as prevention of the vascular causes of cognitive impairment.
Assuntos
Encéfalo/patologia , Disfunção Cognitiva/etiologia , Disfunção Cognitiva/patologia , Demência Vascular/complicações , Animais , Encéfalo/diagnóstico por imagem , Disfunção Cognitiva/diagnóstico por imagem , Demência Vascular/diagnóstico por imagem , Humanos , NeuroimagemRESUMO
Vascular dementia (VaD) is a major contributor to the dementia syndrome and is described as having problems with reasoning, planning, judgment, and memory caused by impaired blood flow to the brain and damage to the blood vessels resulting from events such as stroke. There are a variety of etiologies that contribute to the development of vascular cognitive impairment and VaD, and these are often associated with other dementia-related pathologies such as Alzheimer disease. The diagnosis of VaD is difficult due to the number and types of lesions and their locations in the brain. Factors that increase the risk of vascular diseases such as stroke, high blood pressure, high cholesterol, and smoking also raise the risk of VaD. Therefore, controlling these risk factors can help lower the chances of developing VaD. This update describes the subtypes of VaD, with details of their complex presentation, associated pathological lesions, and issues with diagnosis, prevention, and treatment.