Mon projet de thèse a été dédié à l’étude des synucléinopathies. Ces maladies neurodégénératives sont caractérisées par la présence d’inclusions intracytoplasmiques positives pour l’alpha-synucléine et contenues dans les neurones pour la maladie de Parkinson (i.e. les corps de Lewy) ou dans les oligodendrocytes pour l’atrophie multisystématisée (i.e. les inclusions cytoplasmiques oligodendrogliales). L’objectif de mon travail de thèse fut de proposer une approche multifactorielle et translationnelle en développant les aspects de modélisation, de mécanistiques et de thérapeutiques associées aux synucléinopathies. Nous nous sommes tout d’abord intéressés à disséquer les mécanismes sous-jacents à la neurodégénérescence induits par la protéine alpha-synucléine dans un modèle primate non-humain de la maladie de Parkinson. Nous avons ainsi souligné le rôle toxique de la protéine alpha-synucléine et mis en lumière de nouveaux processus cellulaires impliqués dans le phénomène de neurodégénérescence. Dans ce même modèle animal, nous avons étudié l’hypothèse d’une propagation de la pathologie induite par l’alpha-synucléine entre les systèmes nerveux centraux et périphériques. Nous avons ainsi pu démontrer l’existence d’une route bidirectionnelle de propagation et de neurodégénérescence de la protéine entre les deux systèmes nerveux, pouvant corroborer la présence de symptômes non moteurs précoces au cours de la pathologie. Enfin, nous nous sommes concentrés sur le rétablissement de la fonction autophagique comme cible thérapeutique commune aux synucléinopathies. Nous avons ainsi pu démontrer qu’une restauration de la machinerie de dégradation de la voie autophagie était suffisante pour rétablir les taux physiologiques de la protéine alpha-synucléine et induire une neuroprotection dans un modèle rongeur de la maladie de Parkinson et d’atrophie multi-systématisée. Ces travaux corroborent le rôle clé de la protéine alpha-synucléine dans l’étiologie des synucléinopathies et proposent de nouvelles stratégies thérapeutiques communes à toutes les synucléinopathies afin de rétablir les niveaux physiologiques cellulaires de la protéine et une neuroprotection au sein du système nerveux central. / My thesis project was dedicated to the study of synucleinopathies. Synucleinopathies are neurodegenerative diseases characterized by the presence of alpha-synuclein positive intracytoplasmic inclusions which are present either in neurons for Parkinson’s disease (i.e. Lewy Bodies) or in oligodendrocytes for Multiple system atrophy (i.e. Glial Cytoplasmic Inclusions). The aim of my work was to establish a multifactorial and translational approach through modeling, mechanistic and therapeutic aspects associated with synucleinopathies. First, we focused on dissecting the underlying alpha-synuclein-mediated mechanisms of neurodegeneration using a non-human primate model of Parkinson’s disease. We confirmed the toxic role of alpha-synuclein in the pathology and highlighted unpredictable cellular processes involved in neurodegeneration. Using the same Parkinson’s disease model, we studied the hypothesis of a pathological propagation between the central and peripheric nervous systems in an attempt to decipher the initiation point and the direction of propagation of the associated pathology. We thus demonstrated a bidirectional route of propagation of alpha-synuclein between the CNS and the ENS and within the ENS. Finally, we focused on the restoration of the autophagic function as a potential common therapeutic target for all synucleinopathies. We demonstrated through a gene-based restoration of the autophagy, we efficiently reestablish alpha-synuclein physiological protein levels, while inducing neuroprotection in a Parkinson’s disease and Multiple system atrophy rodent models. Thus, this work corroborates the key role of alpha-synuclein in the etiology of synucleinopathy and offers new common therapeutic strategies for all synucleinopathies to decrease alpha-synuclein-induced toxicity into the central nervous system.

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder and the leading cause of human senile dementia. Alzheimer’s represents a significant public health concern, having widespread social and economic implications. Consequently, protocols for early detection and therapeutic intervention (both behavioral and pharmacologic) constitute important targets for medical investigation. Furthermore, contemporary research depends upon comprehensive neurobehavioral assessment and advanced statistical and computational analytic methodologies for characterizing AD-associated sensorimotor and cognitive impairment, as well as evaluating therapeutic efficacy. This dissertation introduces data mining-based techniques (decision trees, neural networks, support vector machines) for behavioral analysis in both nontransgenic and Alzheimer’s transgenic mice, to evaluate the cognitive benefits of long-term caffeine treatment. Both treatment and transgenic effects are identified through advanced statistical (discriminant analysis) and data mining approaches. In addition, a novel mouse-based cognitive assessment paradigm, adapted from a human interference learning AD-diagnostic protocol, is implemented to evaluate both genetic (GRK5) and therapeutic (GM-CSF) effects in mice, against an Alzheimer’s transgenic background. Data mining techniques are shown to be comparable to con ventional statistical analyses, often providing complementary diagnostic information. Indeed, comparisons between data mining-based and multivariate statistical analyses, with respect to groupwise discriminability, support the use of both methodologies in neurobehavioral research. Future work involving both data mining-based and multivariate statistical analyses of cognitive-behavioral data is discussed, emphasizing the need for longitudinal studies, repeated-measure designs, and spatiotemporal modeling for evaluating the time-course of both human AD and AD-like pathology in transgenic mouse models.

Idiopathische Myositiden stellen die größte Gruppe der erworbenen Myopathien im Erwachsenenalter dar. Die Pathogenese dieser Erkrankungen ist sehr heterogen und nicht in allen Einzelheiten geklärt. Das Auftreten von mitochondrialen Veränderungen und mtDNADeletionen in idiopathischen Myositiden und deren pathophysiologische Bedeutung ist in der Literatur ein kontrovers diskutiertes Thema. Nach der Präsentation des bekannten Wissens über diese Erkrankungen wird in vorliegender Arbeit dieses Thema anhand lichtmikroskopischer Methoden unter Anwendung histologischer Spezialmethoden an Muskelbiopsien von 98 Patienten untersucht. Ziel der Arbeit ist es, mit verschiedenen histologischen Färbemethoden Hinweise für Mitochondrien-Alterationen und feinstrukturelle Charakteristika von primären Mitochondrialen Myopathien in idiopathischen Myositiden zu detektieren. Ein besonderer Schwerpunkt liegt auf der Anwendung einer neuen immunhistochemischen Methode unter Anwendung eines monoklonalen antimitochondrialen Antikörpers. Es wird der Fall eines Mädchens mit muskeldystrophischer Symptomatik dargestellt, dessen Muskelbiopsie im Alter von 7 Jahren die myohistologische Diagnose einer juvenilen Dermatomyositis und Hinweise auf eine mitochondriale Dysfunktion ergab. Die Ergebnisse der immunhistochemischen Methode korrelieren gut mit anderen bekannten mitochondrialen Färbungen, sind sensitiver und stellen möglicherweise eine gute Ergänzung zu den bekannten mitochondrialen Markern und Färbungen dar. Die beobachteten mitochondrialen Dysfunktionen sprechen für die gestörte Mitochondrienfunktion und eine früh im Krankheitsverlauf, am ehesten sekundäre, Beteiligung der Mitochondrien im Krankheitsprozess dieser primär nicht mitochondrialen Erkrankungen

West Nile Virus (WNV) has emerged as a major cause of viral encephalitis. Since its outbreak in the United States 27,000 people have presented with clinical WNV disease resulting in 1074 fatalities. WNV causes a range of disease from mild febrile illnesses to severe and fatal encephalitis. To date, there are currently no therapeutic agents or vaccines available to treat WNV infection in humans. In order to address this, a better understanding of the mechanisms responsible for viral neuroinvasion and neuropathology are required. Using a range of in vitro and in vivo studies, we have investigated the routes by which WNV enters the CNS. Virus replication was observed in the brain microvascular endothelial cells in mice that succumbed to WNV encephalitis. Moreover, we demonstrated that infection of a polarized HBMEC with WNV induced apoptosis. Microarray analysis of WNV-infected HBMEC’s revealed that WNV elicited the expression of cytokines that have been shown to contribute to permeablization of the BBB. These findings suggest that WNV can enter the CNS through the BBB via multiple mechanisms. Real-time RT-PCR performed on WNVinfected HBMECs identified two host genes involved in the host cellular anti-oxidant response that were differentially regulated during viral infection. Furthermore, the addition of the antioxidant, N-acetylcysteine, restored cell viability and decreased viral replication, indicating that oxidative stress contributes to WNV-induced pathogenesis. The current state of knowledge regarding the pathogenesis of WNV encephalitis is based on studies that have defined the role of systemic immune responses to WNV. Limited investigations have been undertaken to determine the contribution of brain cells in the defence, or damage to the brain once WNV has gained access to the CNS. Real-time RT-PCR results in conjunction with in vivo CBA assay data, suggested several candidate host genes that could contribute to the pathogenesis of WNV. Thus, it is necessary to further define the mechanisms of WNV induced pathogenesis as this will aid in the development of targeted strategies to prevent neurological infection and mitigate neurological diseases in affected individuals.

Hyperglycemia associated with diabetes has been recognized for adverse neurodegenerative effects it has on the central nervous system (CNS). However, few cerebral histopathological studies have been completed to adequately define the neuropathology of type 2 diabetes. The aim of the study was to conduct a neuropathological survey of diabetic Zucker Diabetic Sprague Dawley (ZDSD) rat brains that included a wide variety of potential pathologies. Ten ZDSD rat brains (diabetic: n=6 non-diabetic obese: n=4) were collected for neuropathological assessments. Specific measures include assessments of gray and white matter atrophy, neurodegeneration, astrocyte activation, blood brain barrier integrity, inflammation, and amyloid protein deposit. After brain sectioning, formal thionin, immunoglobulin G (IgG), glial fibrillary acidic protein (GFAP), giemsa, congo-red, and flourojade (FJ) stains were performed for analysis. Of the several neuropathological assessments, two revealed significant differences between diabetic and non-diabetic groups. Diabetic ZDSD rats had a relative decrease in the amount of white matter in the corpus callosum underlying the cingulate cortex of the brain. Secondly, higher numbers of lymphocytes were observed in the hypothalamus of the diabetic rats compared to non-diabetic rats. Enhanced expression of GFAP was not present. No measurable differences were observed in analysis of amyloid, FJ intensity levels or immunoglobulin G (IgG) extravisation into the brain. These results suggested that ZDSD rats do not exhibit neuropathology excepting white matter atrophy and increased lymphocyte infiltration into the hypothalamus, or that the duration of 6-7 month old diabetic ZDSD rats may be insufficient to support most of our hypotheses. Future work is required to determine profiles of neuropathology in longer term of diabetic ZDSD rats.

Old-age hippocampal sclerosis (HS), characterised by severe neuron loss in hippocampal CA1, is a poorly understood cause of dementia. At present no objective pathological HS criteria exist. In life HS is commonly diagnosed as Alzheimer's disease. HS aetiology is unclear, although it has been associated with both ischaemia and TAR-DNA-binding protein-43 (TDP-43)-related neurodegeneration. Variations in genes GRN, TMEM106B and ABCC9 are proposed as HS risk factors. The aim of this thesis was to investigate epidemiological, clinical, pathological and genetic characteristics of HS in older European populations. 976 brains donated for the Cambridge City over-75s Cohort, the Cognitive Function and Ageing Study and the Finnish Vantaa 85+ study were available for evaluation -including bilateral hippocampi from 302 individuals. A protocol capturing the extent and severity of hippocampal neuron loss was developed, establishing objective HS diagnosis criteria and allowing observation of distinct neuron loss patterns associated with ischaemia and neurodegeneration. 71 HS cases (overall prevalence: 7.3%) were identified. HS was significantly associated with an advanced age at death as well as dementia at the end of life. Neuropsychological and cardiovascular characteristics were similar between HS and AD, except for a longer duration of dementia and more disability in HS. HS was not associated with neurofibrillary tangles, amyloid plaques, or vascular pathologies, but all HS cases evaluated for TDP-43 showed neuronal inclusions in the hippocampal dentate and a high frequency of other glial, neuronal and neurite TDP-43 pathologies. GRN and TMEM106B but not ABCC9 variations were linked to HS. A moderating effect of TDP-43 on this association was detected. HS presented pathologically similarly to frontotemporal dementia cases with TDP-43 (FTLD-TDP) caused by mutations in GRN, but differed from other FTLD-TDP subtypes. Results of this thesis reveal the importance of HS in the oldest old in the population, the key role of TDP-43, as well as providing robust methods to capture HS characteristics for an area that has been under-researched but is clearly vital to understanding dementia in the oldest old.

Made available in DSpace on 2014-06-11T19:33:27Z (GMT). No. of bitstreams: 0 Previous issue date: 2003-02-18Bitstream added on 2014-06-13T19:44:14Z : No. of bitstreams: 1 vasconcelos_ro_dr_jabo.pdf: 1349333 bytes, checksum: 7eaa9b531ee75109ac659bcca081d17c (MD5) / A compreensão do comportamento da microglia frente a uma injúria viral contribui para o entendimento da dimensão da rede de comunicação celular, durante um processo degenerativo ou inflamatório no SNC. Pesquisas que utilizam modelos experimentais com o vírus da estomatite vesicular (VEV) têm colaborado com informações importantes sobre o comportamento e distribuição do agente no encéfalo, e também sobre o papel da resposta imune na resolução ou no agravamento das lesões nervosas. Neste estudo, foi comparada a evolução do quadro neurológico induzido pelo VEV, por meio de técnicas de imunoistoquímca, em cérebros de camundongos. Foi possível observar que o VEV causa severa degeneração e necrose do neurópilo, com lesão direta em neurônios, pois estes mostraram-se claramente positivos para o vírus, por meio da reação de imunoistoquímica no cérebro. A reação astrocitária foi intensa nos animais infectados, porém a densidade destas células reduziu com o aumento da gravidade das lesões. As células residentes (neurônios, astrócitos e microglia) e as células inflamatórias expressaram MIP-1a e, em menor proporção, MIP-1b. A microgliose reativa foi significativa nos animais com sintomatologia clínica. A diversidade morfológica da microglia foi grande, variando desde uma forma fusiforme a uma ramificada e a forma arredondada fagocítica das áreas necróticas. Foi possível observar que existe uma profunda interação entre as células residentes do SNC - neurônios, microglia, astrócitos, endotélio, frente ao estímulo viral. Baseado nos relatos da literatura é importante salientar que os astrócitos mantêm um controle ativo sobre a microglia tanto em repouso quanto ativada, via citocinas/quimiocinas. A densidade aumentada dessas células coincidiu com a redução do número de astrócitos, devido à necrose do neurópilo... / The comprehension of the microglial cell behavior in a viral injury colaborate for the understanding of the dimension of the cellular communication net, during a degenerative or inflammatory process in central nervous system (CNS). Experimental models with the vesicular stomatitis virus (VSV), has contributed with important information about the behavior and distribution of virus in the CNS. Such studies evaluated the role of the immune response in the resolution or in the damage of the nervous lesions. In this study, the evolution of the neurological signals and lesions induced by VSV infection in mice was studied, using imunohistochemical techniques. It was observed that VSV causes severe degeneration and necrosis of the neuropil and direct lesions to the neurons. The neurons were the most intensively stained cells for the virus in the brain. The reactive astrocitosis was intense in the infected animals, but the density of these cells reduced with the increase of the gravity of the lesions. The resident and inflammatory cells expressed MIP-1a and in smaller proportion MIP-1b, in different cellular types (neurons, astrocytes and microglia). The reactive microgliosis was significant in animals with clinical symptomatology and there was a great morphologic microglial diversity, varying from a fusyforme form and ramified form and the fagocitic round form of the around necrotics areas. It was possible to observe that a close interaction exists among the resident cells of SNC (neurons, microglia, astrocytes, endothelial cells) in face of the viral infection. Based on the reports of the literature it is important to point out that the astrocytes maintains an active control on the microglia (in resting or activated cells), through citokines/chemokines. The increased density of microglia coincided with the reduction of the astrocytes number, due to the necrosis of the neuropil... (Complete abstract, access undermentioned eletronic address)

Acute hospitals have seen unprecedented demographic changes, where older age, frailty and cognitive impairment now characterise the majority of health service users. Delirium is very common in this setting, and adverse outcomes are well described. However, studies investigating cognitive outcomes after delirium in unselected samples have been lacking. This thesis had four objectives: (1) To estimate the prevalence of delirium in the general population (2) To assess the association of delirium with cognitive outcomes (3) To investigate how these associations relate to underlying dementia pathology (4) To develop novel methods for retrospectively ascertaining delirium. Methods: Data from three population-based neuropathology cohort studies were used: Vantaa 85+; Cambridge City over-75s Cohort (CC75C); MRC Cognitive Function and Ageing Study (CFAS). (1) To ascertain the prevalence of delirium in the general population, a measure of delirium was developed using data recorded in standardised interview schedules, with criterion validity evaluated through the association with mortality and dementia risk. (2) The association with cognitive outcomes was tested in a series of logistic regression models, where delirium was the exposure and dementia (or worsening dementia severity) was the outcome. In addition, the association with change in Mini-Mental Status Examination (MMSE) score was assessed using random-effects linear regression. (3) In brain donors from all three cohorts, the independent effects of delirium, dementia pathology, and their interaction, were investigated using the same approach. (4) A chart-based method for deriving a retrospective diagnosis for delirium was developed, validated against bedside psychiatrist diagnosis. Vignettes from the medical record were abstracted and delirium status decided by expert consensus panel. Results: (1) Age-specific prevalence in CFAS increased with age from 1.8% in the 65-69 year age group to 13.5% in the ≥90 age group (p<0.01 for trend). (2) Delirium was consistently associated with adverse cognitive outcomes: new dementia (OR 8.7, 95% CI 2.1 to 35); worsening dementia severity (OR 3.1, 95% CI 1.5 to 6.3); faster change in Mini-Mental Status Examination (MMSE) score (1.0 additional points/year, p<0.01) (3) In the neuropathology analyses, decline attributable to delirium was -0.37 MMSE points/year (p<0.01). Decline attributable to dementia pathology was -0.39 MMSE points/year (p<0.01). However, the combination of delirium and dementia pathology resulted in the greatest decline, where the interaction contributed a further -0.16 MMSE points/year (p=0.01), suggesting that delirium worsened cognitive trajectories in dementia, but through distinct pathophysiological pathways not accounted for by Alzheimer’s, vascular or Lewy body pathology. (4) The chart abstraction method yielded a sensitivity of 0.88 and specificity 0.75 for ‘possible delirium’, with lower sensitivity (0.58) and higher specificity (0.93) for ‘probable delirium’ (AUC 0.86, 95% CI 0.82 to 0.89). This thesis adds to the small body of work on delirium in prospective studies, with the first ever analyses conducted in whole populations. The findings suggest new possibilities regarding the pathology of cognitive impairment, positioning delirium and/or its precipitants as a critically inter-related mechanism.

The postmortem human brain as a tool to study central nervous system disease Abnormalities in noradrenergic transmission are likely to play a role in behavioral expressions of a number of psychiatric and neurological disorders. The extent to which these abnormalities are pathognomonic, or even principal pathological features contributing to the illness, remains debatable. Interest in the potential for pathological abnormalities in central norepinephrine in central nervous system (CNS) disorders derives from the three general observations: (1) disruption of behaviors known to be heavily influenced by noradrenergic transmission that are associated with the illness; (2) demonstration that pharmacological manipulation of noradrenergic transmission can precipitate, modify, or alleviate symptoms of these disorders; and (3) certain CNS disorders are characterized pathologically by a loss of noradrenergic neurons in the brain. Research on the pathology of central noradrenergic systems in CNS diseases and their relationship to behavioral alterations utilizes a variety of techniques, most of which are technically indirect, given that we currently are unable to directly measure noradrenergic neuron activity, noradrenergic receptor signaling, or norepinephrine release in vivo in living humans. In vivo imaging methods now permit investigators to measure occupancy of certain receptors, but application of these methods specifically to noradrenergic proteins, such as receptors, enzymes or transporters, has been limited. One method to study the role of norepinephrine in the CNS disorders is to utilize postmortem brain tissue from subjects with a given psychiatric or neurological condition.

Mucopolysaccharidosis (MPS) IIIB is a lysosomal storage disease with severe neurological manifestations due to a-N-acetylglucosaminidase (NaGlu) deficiency. The mechanism of neuropathology in MPS IIIB is unclear. This study investigates the role of immune responses in neurological disease of MPS IIIB in mice. By means of gene expression microarrays and realtime quantitative reverse transcriptase-polymerase chain reaction, we demonstrated significant up-regulation of numerous immune-related genes in MPS IIIB mouse brain involving a broad range of immune cells and molecules, including T cells, B cells, microglia/ macrophages, complement, major histocompatibility complex class I, immunoglobulin, Toll-like receptors, and molecules essential for antigen presentation. The significantly enlarged spleen and lymph nodes in MPS IIIB mice were due to an increase in splenocytes/lymphocytes, and functional assays indicated that the T cells were activated. An autoimmune component to the disease was further suggested by the presence of putative autoantigen or autoantigens in brain extracts that reacted specifically with serum IgG from MPS IIIB mice. We also demonstrated for the first time that immunosuppression with prednisolone alone can significantly slow the central nervous system disease progression. Our data indicate that immune responses contribute greatly to the neuropathology of MPS IIIB and should be considered as an adjunct treatment in future therapeutic developments for optimal therapeutic effect.