Alzheimer's disease (AD) is the most common neurodegenerative disease, characterized by progressive amyloid plaque aggregation, neurofibrillary tangles, and cortical tissue death. As the prevalence of AD is projected to climb in coming years, there is a vested interest in identifying endophenotypes by which to improve diagnostics and direct clinical interventions. The risk for complex disorders, such as AD, is influenced by multiple genetic, environmental, and lifestyle factors. Significant strides have been made in identifying genetic variants linked to AD through the genome-wide association study (GWAS). It has been estimated in more recent years, however, that GWAS-identified variants account for limited AD heritability, suggesting the role of non-sequence genetic mechanisms, such as epigenetic moderators. By influencing gene expression, epigenetic markers have been linked to age- associated decline through modulation of chromatin architecture and global genome instability, though such mechanisms are also involved with a number of normal biological processes, including neurogenesis. As the strategies of clinical genetics shift to include a heavier focus on epigenetic contributors, altered adult neurogenesis presents itself as a strong candidate for an endophenotype of AD development. This thesis proposes that, due to neuropathological dysfunction of epigenetic mechanisms in AD, new generations of neurons fail to proliferate, differentiate, and mature correctly, resulting in the larger loss of neurons and cognitive deficits characteristic to neurodegenerative disease. The plasticity of the epigenome and the role of epigenetic factors as mediators of the genome and the environment make such alterations attractive in AD research and implies the potential for therapeutic interventions. The present review submits neurogenesis as a viable target of epigenetic research in AD, highlights shared loci between neurogenesis and AD in the epigenome, and considers the promises and limitations of the neurogenic endophenotype.

Cerebrovascular disease is a major cause of dementia in elderly individuals, especially Black/African Americans. Within my dissertation, we focused on two vascular morphologies that affect small vessels: brain arteriolosclerosis (B-ASC) and multi-vascular profiles (MVPs). B-ASC is characterized by degenerative thickening of the wall of brain arterioles. The risk factors, cognitive sequelae, and co-pathologies of B-ASC are not fully understood. To address this, we used multimodal data from the National Alzheimer’s Coordinating Center, Alzheimer’s Disease Neuroimaging Initiative, and brain-banked tissue samples from the University of Kentucky Alzheimer’s Disease Center (UK-ADC) brain repository. We analyzed two age at death groups separately: < 80 years and ≥ 80 years. Hypertension was a risk factor in the < 80 years at death group. In addition, an ABCC9 gene variant (rs704180), previously associated with aging-related hippocampal sclerosis, was associated with B-ASC in the ≥ 80 years at death group. With respect to cognition as determined by test scores, severe B-ASC was associated with worse global cognition in both age groups. With brain-banked tissue samples, we described B-ASC’s relationship to hippocampal sclerosis of aging (HS-Aging), a pathology characterized by neuronal cell loss in the hippocampal region not due to Alzheimer’s disease. We also studied MVPs, which are characterized by multiple small vessel lumens within a single vascular (Virchow-Robin) space. Little information exists on the frequency, risk factors, and co-pathologies of MVPs. Therefore, we used samples and data from the UK-ADC, University of Kentucky pathology department, and University of Pittsburgh pathology department to address this information. We only found MVPs to be correlated with age. Lastly, given the high prevalence of cerebrovascular disease and dementia in Black/African Americans, we discussed the challenges and considerations for studying Blacks/African Americans in these contexts.

Doctor of Philosophy (PhD) / Proteomics is rapidly achieving recognition as a complimentary and perhaps superior approach to examine global changes in protein abundance in complex biological systems and the value of these techniques in neuropsychiatry is beginning to be acknowledged. Characterizing the brain’s regional proteomes provides a foundation for the detection of proteins that may be involved in disease-related processes. Firstly, optimal conditions were achieved for the application of two dimensional-gel electrophoresis (2D-GE)-based proteomics with postmortem human brain tissue. These optimized techniques were then applied to soluble fractions of adjacent grey and white matter of a single cytoarchitecturally defined area (Brodmann area 9; BA9) and of two adjacent regions of frontal white matter (BA9 and CC body) from healthy individuals. These normative proteomic comparisons highlighted the importance of correct tissue sampling, i.e. proper separation of regional white matter, as heterogeneity in the respective proteomes was demonstrated. Furthermore, they stressed the necessity for future molecular brain mapping studies. The main focus of this thesis however, was to examine the proteomes of brain regions specifically vulnerable to alcohol-induced damage underlying cognitive dysfunction. Alcoholic patients commonly experience mild to severe cognitive decline. It is postulated that cognitive dysfunction is caused by an alcohol-induced region selective brain damage, particularly to the prefrontal cortex. The cerebellum is increasingly recognized for its role in various aspects of cognition and alcohol–induced damage to the cerebellar vermis could indirectly affect neurocognitive functions attributed to the frontal lobe. We used a 2D-GE-based proteomics approach to compare protein abundance profiles of BA9 grey and white matter and the cerebellar vermis from human alcoholics (neurologically uncomplicated and alcoholics complicated with liver cirrhosis) and healthy control brains. Among the protein level changes observed are disturbances in the levels of a number of thiamine-dependent enzymes. A derangement in energy metabolism perhaps related to thiamine deficiency seems to be important in all regions analysed, even where there are no clinical or pathological findings of Wernicke-Korsakoff Syndrome. Evidence of oxidative changes was also seen in all regions and effects of liver dysfunction in the vermis found. However, overall, these results highlight the complexity of this disease process in that a number of different proteins from different cellular pathways appear to be affected. By identifying changes in protein abundance levels in the prefrontal grey and white matter and the cerebellar vermis, hypotheses may draw upon more mechanistic explanations as to how chronic ethanol consumption causes the structural and functional alterations associated with alcohol-related brain damage. Furthermore, by comparing these results, we may be able to isolate disturbances in molecular pathways specific to the brain damage caused by alcohol, severe liver dysfunction and thiamine deficiency.

Background: Gliomas are neuroepithelial tumours classified by cell type and grade. In adults, low-grade gliomas are comprised mainly of astrocytomas and oligodendrogliomas grade II. The aim was to non-invasively characterise suspected low-grade gliomas through use of 11C-methionine-PET and physiological MRI in order to facilitate treatment decisions. Materials and methods: Patients with suspected low-grade glioma were prospectively and consecutively included after referral to the Neurosurgical Department, Uppsala University Hospital, between February 2010 and February 2014. All patients underwent morphological MRI, perfusion MRI, diffusion MRI and 11C-methionine PET. The institutional review board approved the study, and written informed consent was obtained prior to participation from each patient. Results: 11C-methionine PET hot spot regions corresponded spatially with regions of maximum relative cerebral blood volume in dynamic susceptibility contrast (DSC) perfusion MRI. The skewness of the transfer constantin dynamic contrast-enhanced (DCE) perfusion MRI, and the standard deviation of relative cerebral blood flow in DSC perfusion MRI could most efficiently discriminate between glioma grades II and III. In diffusion MRI, tumour fractional anisotropy differed between suspected low-grade gliomas of different neuropathological types. Quantitative diffusion tensor tractography was applicable for the evaluation of tract segment infiltration. Conclusion: PET and physiological MRI are able to characterise low-grade gliomas and are promising tools for guiding therapy and clinical decisions before neuropathological diagnosis has been obtained.

Doctor of Philosophy (PhD) / Proteomics is rapidly achieving recognition as a complimentary and perhaps superior approach to examine global changes in protein abundance in complex biological systems and the value of these techniques in neuropsychiatry is beginning to be acknowledged. Characterizing the brain’s regional proteomes provides a foundation for the detection of proteins that may be involved in disease-related processes. Firstly, optimal conditions were achieved for the application of two dimensional-gel electrophoresis (2D-GE)-based proteomics with postmortem human brain tissue. These optimized techniques were then applied to soluble fractions of adjacent grey and white matter of a single cytoarchitecturally defined area (Brodmann area 9; BA9) and of two adjacent regions of frontal white matter (BA9 and CC body) from healthy individuals. These normative proteomic comparisons highlighted the importance of correct tissue sampling, i.e. proper separation of regional white matter, as heterogeneity in the respective proteomes was demonstrated. Furthermore, they stressed the necessity for future molecular brain mapping studies. The main focus of this thesis however, was to examine the proteomes of brain regions specifically vulnerable to alcohol-induced damage underlying cognitive dysfunction. Alcoholic patients commonly experience mild to severe cognitive decline. It is postulated that cognitive dysfunction is caused by an alcohol-induced region selective brain damage, particularly to the prefrontal cortex. The cerebellum is increasingly recognized for its role in various aspects of cognition and alcohol–induced damage to the cerebellar vermis could indirectly affect neurocognitive functions attributed to the frontal lobe. We used a 2D-GE-based proteomics approach to compare protein abundance profiles of BA9 grey and white matter and the cerebellar vermis from human alcoholics (neurologically uncomplicated and alcoholics complicated with liver cirrhosis) and healthy control brains. Among the protein level changes observed are disturbances in the levels of a number of thiamine-dependent enzymes. A derangement in energy metabolism perhaps related to thiamine deficiency seems to be important in all regions analysed, even where there are no clinical or pathological findings of Wernicke-Korsakoff Syndrome. Evidence of oxidative changes was also seen in all regions and effects of liver dysfunction in the vermis found. However, overall, these results highlight the complexity of this disease process in that a number of different proteins from different cellular pathways appear to be affected. By identifying changes in protein abundance levels in the prefrontal grey and white matter and the cerebellar vermis, hypotheses may draw upon more mechanistic explanations as to how chronic ethanol consumption causes the structural and functional alterations associated with alcohol-related brain damage. Furthermore, by comparing these results, we may be able to isolate disturbances in molecular pathways specific to the brain damage caused by alcohol, severe liver dysfunction and thiamine deficiency.

Orientador: Antonio Carlos Alessi / Banca: Rosangela Zacarias Machado / Banca: José Luiz Guerra / Banca: João Santana da Silva / Banca: Valéria Marçal Felix de Lima / Resumo: 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... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: 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) / Doutor

Systemic inflammation is thought to be an important driver in chronic neurodegeneration. During systemic infection, the inflammatory status of the periphery is communicated to the brain and conserved sickness behaviours initiated. However, in the context of dementia the same inflammatory stimulus might trigger delirium. Delirium is a severe, transient neuropsychiatric condition characterised by altered levels of arousal, inattention, cognitive deficits and psychoses. Delirium and systemic inflammation exacerbate the trajectory of pre-existing dementia, and are associated with increased risk of future dementia. Accumulating experimental studies suggest microglia are “primed” by chronic neurodegeneration, such that a subsequent inflammatory insult – central or systemic – induces an increased inflammatory response which manifests as exaggerated sickness behaviours. To date there have been no studies of microglial priming in the context of pure tau pathology, without amyloid pathology, and none investigating acute sickness behaviour in such a model. The overarching aim of this thesis is to address this gap in the literature and further our understanding of the interactions between systemic inflammation, neuroinflammation and neurodegeneration in the context of tauopathy. The P301S mouse over-expresses human mutant tau protein under the Thy1.2 promoter. It develops hyperphosphorylated and insoluble tau accumulations and progressive neuronal loss. Consequently, P301S mice develop progressive hind limb paralysis. This study identified the horizontal bar task, a test of motor control and coordination, conducted at weekly intervals from 8-22 weeks of age, as a non-invasive measure of disease progression. In addition, a detailed temporal profile of pathological hallmarks at 8, 9, 10, 11, 12, 16 and 20 weeks of age was determined. Key results presented here demonstrate progressive, superficial neuronal loss in the cortex of P301S mice, with associated astrogliosis and surprisingly this occurs in the absence of apparent cortical microgliosis. In stark contrast, there is progressive microgliosis in the spinal cord of P301S mice. On this background, lipopolysaccharide (LPS), a chemical moiety found on the outer surface of gram-negative bacteria, was used to mimic a systemic bacterial infection. P301S mice and C57BL/6 control mice were injected, at 10 or 16 weeks of age, intraperitoneally with 500 μg/kg LPS or saline and were monitored in the following hours and weeks. Acutely, P301S mice showed signs of an exaggerated, longer lasting sickness response. Importantly, exaggerated acute symptoms extended beyond those typically associated with sickness behaviour; LPS induced an exaggerated acute impairment of horizontal bar performance in P301S mice and not C57BL/6 mice – a function which is known to be impaired in P301S mice later in disease. Impairments were age-dependent in terms of timing of injection. These data suggest an interaction between acute infection and existing CNS vulnerability leading to acute neurological dysfunction that is not a feature observed in sickness in a normal animal. LPS-injected P301S mice also showed, again age-dependent, increased rate of decline in motor performance compared with controls. There was no evidence of microglial priming in P301S mice. LPS caused an acute increase in AT8-positive phospho-tau however this did not persist until end stage. At 22 weeks of age there was significant disease-associated cortical neuronal loss in the vehicle-injected P301S mice, and additional superficial cortical neuronal loss in LPS-injected P301S mice and control mice. There was significant IBA1-positive microgliosis in the spinal cord of P301S mice at end stage which was further increased in LPS-injected P301S mice. Taken together these data indicate a clear and clinically relevant interaction between systemic inflammation and tau-associated neuropathology with acute and long-term functional consequences. In the absence of evidence of microglial priming, future work will explore potential mechanisms.

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No. of bitstreams: 2 Dissertação Victor de Melo Caixeta - 2015.pdf: 2750656 bytes, checksum: c7c2c97e0c6537b3d17aa54409152ad3 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2015-10-15 / Background: Corticobasal Degeneration (CBD) is an rare and heterogeneous disease in its presentations, representing an great diagnostic challenge. There aren´t, in Brasil, large CBD case series, and there aren´t many in the world as well. Its cognitive and behavioural aspects have received little (despite growing) attention. Objectives: To describe sociodemographic, clinic, neuropsychiatric, neuropathological, and neuroradiologic aspects in a large brazilian DCB case series. To perform a literature review on CBD, with special focus on cognitive and behavioural aspects. Methods: 70 patients data was collected, with CBD diagnosis according to the Cambridge criteria modified by Bak and Hodges (2011). The patients underwent clinical, neuropsychiatric, neuroradiologic (structural and functional) and pathologic (in six cases) retrospective analysis. There were studied clinical, sociodemographic, neuropsychiatric, neuroanatomic variables and family history. Results and Discussion: The mean age at onset was 62.8 years (sd=9,5), and both sexes were equally affected (52,9% male). Hemispheric asymmetry was present in 97% of cases, and the left brain hemisphere was the most affected (68,2% of cases). The most frequent initial presentation was “psychiatric” (with changes in behaviour and/or mood), present in 68,1% of cases, followed by motor-extrapyramidal presentation (54.3%). In the course of the disease, the predominant clinical form (phenotype) was the extrapyramidal-motor with 61.4% of cases, followed by "psychiatric" with 51.4%. There were five cases with presentation of Posterior Cortical Atrophy (PCA) In 37.7% there were not found classic CBD syndromes (e.g., alien hand syndrome). We found 18.7% of cases with family DCB, with four families presenting a phenotype not yet described, of CBD with NPH (Normal Pressure Hydrocephalus). We also observed cognitive and functional impairments in the evaluated scales (MMSE, Pfeffer and CDR), and frequent medical and psychiatric comorbidities, especially diabetes mellitus (23.5%), hypothyroidism (22.1%) and Bipolar Spectrum Disorders (46, 4%), the last two significantly more frequent in the sample. There were six cases of rapidly progressive DCB and six confirmed by autopsy CBD cases in the sample. Conclusion: We observed, in agreement with the literature, a wide variety of CBD presentations, including new and little described phenotypes (NPH and PCA). In the characterization of the sample, we observed a great prevalence and importance of cognitive, affective and behavioural presentations. / Introdução: A Degeneração Corticobasal (DCB), é uma doença rara e heterogênea em suas apresentações, representando um grande desafio diagnóstico. Não há descrições de grandes amostras de DCB no Brasil, e poucas no mundo. Seus aspectos cognitivos e comportamentais têm recebido pouca (apesar de crescente) atenção. Objetivos: Descrever aspectos sociodemográficos, clínicos, neuropsiquiátricos, neuropatológicos e de neuroimagem em uma grande série de casos brasileiros com DCB. Realizar uma revisão da literatura sobre a DCB, com especial enfoque em aspectos cognitivos e comportamentais. Metodologia: Foram colhidos dados de 70 pacientes com DCB de acordo com critérios de Cambridge modificados por Bak e Hodges (2011). Os pacientes foram submetidos à avaliação retrospectiva clínica e neuropsiquiátrica, de neuroimagem estrutural e funcional e seis pacientes ao exame neuropatológico. Foram estudadas variáveis sociodemográficas, clínicas, neuropsiquiátricas, neuroanatômicas, e antecedentes familiares. Resultados e Discussão: A idade média de início dos sintomas foi de 62,8 anos (dp=9,5), sendo os dois sexos igualmente afetados (52,9% masculino). Assimetria hemisférica esteve presente em 97% dos casos e o hemisfério esquerdo foi o mais acometido (68,2% dos casos). A apresentação inicial mais freqüente foi a “psiquiátrica” (com alterações do comportamento e/ou humor), presente em 68,1% dos casos, seguida da apresentação motora-extrapiramidal (54,3%). No decorrer da doença, a forma clínica (fenótipo) predominante foi a motora-extrapiramidal, com 61,4% dos casos, seguida da “psiquiátrica”, com 51,4%. Houve cinco casos com apresentação de Atrofia Cortical Posterior (ACP). Em 37,7% não ocorreram achados clássicos da DCB (por exemplo, síndrome da mão estrangeira). Encontramos 18,7% de casos com DCB familiar, com quatro famílias apresentando um fenótipo ainda não descrito, de DCB com HPN (Hidrocefalia de Pressão Normal). Observamos também prejuízos cognitivos e funcionais nas escalas avaliadas (MEEM, Pfeffer e CDR), e comorbidades clínicas e psiquiátricas frequentes, em especial Diabetes Mellitus (23,5%), hipotireoidismo (22,1%) e Transtornos do Espectro Bipolar (46,4%), os dois últimos com frequência na amostra significativamente maior que na população. Houve seis casos de DCB rapidamente progressiva e seis casos confirmados por necropsia na amostra. Conclusão: Observamos, em consenso com a literatura, uma grande variedade de apresentações da DCB, inclusive com formas novas e pouco descritas (HPN e ACP). Na caracterização da amostra, percebemos grande frequência e importância das apresentações comportamentais, afetivas e cognitivas.

No description available.

Despite a comprehensive mapping of the Parkinson's disease (PD)-related mRNA and protein leucine-rich repeat kinase 2 (LRRK2) in the mammalian brain, its physiological function in healthy individuals remains enigmatic. Based on its structural features and kinase properties, LRRK2 may interact with other proteins involved in signalling pathways. Here, we show a widespread LRRK2 mRNA and/or protein expression in expanded or differentiated human mesencephalic neural progenitor cells (hmNPCs) and in post-mortem substantia nigra PD patients. Using small interfering RNA duplexes targeting LRRK2 in hmNPCs following their differentiation into glia and neurons, we observed a reduced number of dopaminergic neurons due to apoptosis in LRRK2 knockdown samples. LRRK2-deficient hmNPCs exhibited elevated cell cycle- and cell death-related markers. In conclusion, a reduction of LRRK2 expression in hmNPCs severely impaired dopaminergic differentiation and/or survival of dopaminergic neurons most likely via preserving or reactivating the cell cycle.