Thesis (Ph.D.)--University of Florida, 2005. / Typescript. Title from title page of source document. Document formatted into pages; contains 142 pages. Includes Vita. Includes bibliographical references.

Microglia, the innate immune cells of the brain, are not only immune surveyors, but also play important roles in neural development and maintenance. Microglial aberrations, including changes in morphology, gene expression, and phagocytic activity, have been observed in humans and animal models of pathologies involving cognitive and behavioral consequences. However, the precise contribution of microglial biology is not well characterized. Expression profiling of microglia and neural stem cells, co-culture assays, and transgenic mice were used to identify microglial micro-RNAs and genes, and study their roles in neural development. The results show that a specific micro-RNA, miR-155, participates in the neurogenic deficits induced by inflammation, and microglia-derived Wnt5a is essential for neural differentiation and maturation. This indicates the potential involvement of abnormal microglia in neurodevelopmental disorders such as autism spectrum disorders (ASDs). ASDs are group of debilitating disorders characterized by behavioral symptoms, including social and communication deficits and repetitive or restricted behaviors. I hypothesize that aberrant microglial biology plays a role in neurogenic and behavioral deficits in a mouse model of ASD. I performed a time-course study of microglial gene expression profiling, neural and microglial morphology, neurophysiology, and behavior in the maternal immune activation (MIA) model of ASD induced by the innate immunity ligand polyinosinic:polycytidylic acid. Microglia in MIA offspring displayed altered expression of 22 genes including 14 involved in cell-cell interaction, increased complexity of branching, and increased interactions with dendritic spines of cortical layer V pyramidal neurons. Microglial abnormalities were associated with neurophysiological alterations, measured by whole-cell patch clamp recordings, increased neuronal spine density, and ASD-like behaviors. MIA offspring treated with a colony stimulating factor -1 receptor inhibitor, to deplete and replenish microglia, showed correction of specific behaviors, microglial gene expression and branching, microglia-spine interactions, and spine density, and partial correction of neurophysiology. The data presented here shed new insight into the functional effects of microglia gene and microRNA expression in neurodevelopment. Furthermore, inflammation induces microglial aberrations that lead to altered neurodevelopment; this strongly supports the idea that targeting specific microglial genes and miRNAs will be a worthwhile approach to pursue for molecular intervention in ASD and related disorders. / 2018-11-02T00:00:00Z

AN ABSTRACT OF THE THESIS OF AIDAN CHRISTIE SMITH, for the MASTER OF ARTS degree in PSYCHOLOGY, presented on OCTOBER 27th, 2017, at Southern Illinois University Carbondale. TITLE: EFFECTS OF NICOTINAMIDE ON MICROGLIAL RESPONSE IN JUVENILE RATS AFTER CONTROLLED CORTICAL IMPACT MAJOR PROFESSOR: Dr. Michael J. Hylin Traumatic brain injury (TBI) is a leading cause of death, cognitive and behavioral disability in children in industrialized nations. Preclinical trials of nicotinamide (NAM) treatment provide neuroprotection and reduced inflammatory responses in adult models of TBI. The primary goal of this study was to address the neuroprotective effects of NAM in the developing brain, specifically, the microglial response that occurs following injury. Animals received a bilateral craniotomy with a single cortical contusion injury over the parietal lobe and were treated with either 500mg/kg of nicotinamide or 0.9% saline via intraperitoneal injection. Animals received three injections, 15 minutes, 24 hours, and 48 hours after injury, and were sacrificed at 4 time points, 3 hours, 72 hours, 1 week, or 1 month following injury. Brains were then used for histological assessment for microglial activity. The results show that NAM attenuates the activation of microglia after CCI. Over the course of time, saline treated animals had a marked increase in microglia at 72 hours and remained elevated after 1 week. In NAM treated animals however, there was no significant increase in the number of microglia at any time point. It is suggested here that NAM has a great effect on the inflammatory response. Further studies are needed to examine NAM’s effects on behavior and functional recovery.

Submitted by Hiolanda Rêgo (hiolandarego@gmail.com) on 2015-03-27T12:50:18Z No. of bitstreams: 1 Dissertação_ICS_ Gregory Alves Ferraz.pdf: 1703623 bytes, checksum: 42fd6e6502aa336c756f4be148d6d919 (MD5) / Made available in DSpace on 2015-03-27T12:50:18Z (GMT). No. of bitstreams: 1 Dissertação_ICS_ Gregory Alves Ferraz.pdf: 1703623 bytes, checksum: 42fd6e6502aa336c756f4be148d6d919 (MD5) / neosporose acomete muitas espécies animais, causando-lhes manifestações clínicas de natureza neuro muscular e tem sido apontada como um dos fatores que acarreta prejuízos econômicos na pecuária mundial. Seu agente etiológico, o N. caninum, é controlado por mecanismos de imunidade mediada por células, com destaque de papel protetor para os linfócitos T, que tem variação na sua resposta a depender do tecido parasitado. No sistema nervoso central ocorre um balanço imunológico muito preciso onde a forma infectante do parasito - os taquizoítos - estimula a produção de citocinas do tipo TH1, que acarretariam no controle da sua proliferação. Neste tecido, as células neurogliais parecem responder com a produção de citocinas TH2, com intuito de evitar ou controlar lesões causadas pela resposta pró-inflamatória. O presente estudo investigou o papel imunomodulatório das culturas primárias de microglia durante infecção com taquizoítos de N. caninum. As células, obtidas de cérebro de ratos neonatos, foram infectadas por 72h com o parasito e, para obtenção de controle positivo, foram tratadas com LPS pelo mesmo período. Ensaios de Azul de Trypan e MTT foram realizados para testar a viabilidade celular. Foi observado que as células infectadas e aquelas tratadas com LPS apresentaram significativa perda de viabilidade, cuja causa pode ter sido o aumento significativo dos níveis de nitrito, contudo este evento não contribuiu para o controle da proliferação parasitária. A resposta dessas células ao estímulo parasitário não acarretou tampouco liberação de citocinas inflamatórias (TNF e IFN-γ) e somente quando pré-tratadas com LPS, tiveram níveis de TNF aumentados. Esses dados são compatíveis com a possível modulação negativa da citocina IL-10, que foi encontrada aumentada em ambos tratamentos. Os resultados apontam para a incapacidade das células microgliais isoladas em controlar a proliferação de taquizoítos, ainda que estas, em interação com demais tipos celulares no contexto do tecido cerebral, tenham papel destacado na modulação da resposta ao N. caninum.

Tauopathies are a class of neurodegenerative diseases characterized by aggregation of hyperphosphorylated microtubule associated protein tau (phospho-tau), resulting in neuroinflammation and neurodegeneration. Neuroinflammatory processes play an integral role in the exacerbation and progression of pathology in these disorders, leading to increased levels of neurodegeneration. The RNA binding protein (RBP) T-cell Intracellular Antigen 1 (TIA1) is an important regulator of the innate immune response in the periphery, dampening cytotoxic inflammation and apoptosis during cellular stress, however its role in central neuroinflammation is unclear. We have recently shown that TIA1 regulates tau pathophysiology and toxicity in part through the binding of phospho-tau oligomers into pathological stress granules. Haploinsufficiency of TIA1 in the P301S mouse model of tauopathy results in reduced accumulation of toxic tau oligomers, pathologic stress granules, and the development of downstream pathological features of tauopathy. The putative role of TIA1 as a regulator of the peripheral immune response led us to characterize the role of TIA1 in neuroinflammation, and determine its relationship with neurodegeneration in the context of tauopathy, a chronic stressor in the neural environment. Here, we evaluated indicators of neuroinflammation (reactive microgliosis and phagocytosis, pro-inflammatory cytokine release, and oxidative stress), and neurodegeneration (gross hippocampal atrophy, neuronal loss, synapse loss, and phospho-tau load) in wildtype and P301S transgenic mice expressing TIA1+/+, TIA1+/-, and TIA1-/- in both early (5 month) and advanced (9 month) disease states through biochemical, ultrastructural, and histological analyses. Our data show that both TIA1 haploinsufficiency and TIA1 knockout exacerbate neuroinflammatory processes in advanced stages of tauopathy, suggesting that TIA1 dampens the immune response in the central nervous system during chronic stress. TIA1 haploinsufficiency and knockout do not reduce neurodegeneration in advanced disease, and importantly, TIA1 knockout exacerbates neuron and synapse loss in hippocampal regions. With both increased levels of neuroinflammation and neurodegeneration, P301S animals with TIA1 knockout are distinct from age-matched P301S and wildtype mice. This study demonstrates that TIA1 plays an important role in the regulation of innate immune response in neurodegenerative disease, and its expression significantly impacts the progression of tauopathy.

Indiana University-Purdue University Indianapolis (IUPUI) / Transforming growth factor β-activated kinase 1 (TAK1), a hub kinase at the convergence of multiple signaling pathways, is critical to the development of the central nervous system and has been found to play a role in cell death and apoptosis. TAK1 may have the potential to elucidate mechanisms of cell cycle and neurodegeneration. The Belecky-Adams laboratory has aimed to study TAK1 and its potential roles in cell cycle by studying its role in chick retinal development as well as its possible implication in the progression of diabetic retinopathy (DR). Chapter 3 includes studies that explore TAK1 in a study in chick retinal development and TAK1 in in vitro studies in retinal microglia. Using the embryonic chick, immunohistochemistry for the activated form of TAK1 (pTAK1) showed localization of pTAK1 in differentiated and progenitor cells of the retina. Using an inhibitor or TAK1 activite, (5Z)-7-Oxozeaenol, in chick eye development showed an increase in progenitor cells and a decrease in differentiated cells. This study in chick suggests TAK1 may be a critical player in the regulation of the cell cycle during retinal development. Results from experimentation in chick led to studying the potential role of TAK1 in inflammation and neurodegeneration. TAK1 has previously been implicated in cell death and apoptosis suggesting that TAK1 may be a critical player in inflammatory pathways. TAK1 has been implicated in the regulation of inflammatory factors in different parts of the CNS but has not yet been studied specifically in retina or in specific retinal cells. Chapter 2 includes studies from the Belecky-Adams laboratory of in vitro work with retinal microglia. Retinal microglia were treated with activators and the translocation to the nucleus of a downstream factor of TAK1 was determined: NF-kB. Treatment of retinal microglia in the presence of activators with TAKinib, an inhibitor of TAK1 activation, revealed that TAK1 inhibition reduces the activation of downstream NF-kB. Together this data suggests that TAK1 may be implicated in various systems of the body and further studies on its mechanisms may help elucidate potential therapeutic roles of the kinase.

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Opioids are powerful pain relievers, but also potent inducers of dependence and tolerance. Chronic morphine administration (via subcutaneous pellet) induces morphine dependence in the nucleus accumbens, an important dependence region in the brain, yet the cellular mechanisms are mostly unknown. Toll-like receptor 2 (TLR2) plays an essential function in controlling innate and inflammatory responses. Using a knockout mouse lacking TLR2, we assessed the contribution of TLR2 to microglia activation and development of morphine dependence. We report here that mice deficient in TLR2 inhibit morphine-induced the levels of microglia activation and proinflammatory cytokines. Moreover, in TLR2 knockout mice the main symptoms of morphine withdrawal were significantly attenuated. Our data reveal that TLR2 plays a critical role in morphine-induced microglia activation and dependence.

Indiana University-Purdue University Indianapolis (IUPUI) / Alzheimer’s disease (AD) is a devastating neurodegenerative disease that is expected to affect approximately 6.2 million Americans. Despite its high prevalence, the mechanisms underlying AD remain poorly understood. In recent years, increasing reports indicate that exposure to urban air pollution is a risk factor for the development of AD. However, the mechanistic underpinnings of this association are not well studied. Rats exposed to diesel exhaust (DE) showed neuroinflammation and impaired expression of TREM2 and disease-associated microglia (DAM), a cell subtype hypothesized to play beneficial roles during neurodegeneration, markers. Microglia in the cortex of rats exposed to DE, also showed decreased association with the vasculature, providing a novel link between the microglia and the brain vasculature. Examining the functional role of TREM2 during DE exposures, Trem2-/- mice showed an altered pro-inflammatory profile in both the brain and lungs in response to DE particles as well as altered phagocytic oxidase related gene expression. Examining another prominent component of air pollution, ozone (O3), in a mouse model of AD, it was discovered that subchronic O3 exposure exacerbates amyloid pathology through impaired microglial-plaque association in 5xFAD mice. 5xFAD mice exposed to O3 also showed increased expression of pro-inflammatory cytokines, increased markers of dystrophic neurites, and decreased expression of key acetylcholinergic pathway components. Examining the peri-plaque microenvironment, it was discovered that O3 dysregulates key DAM proteins and amyloid processing proteins. In the lung, it was found that O3 exacerbated immune cell infiltration in 5xFAD mice compared to WT controls, suggesting that ongoing amyloid pathology regulates pulmonary immune response to air pollution. To examine how O3-induced pulmonary immune responses may be signaling to the CNS, we examined the serum of 5xFAD mice, where HMGB1, VEGF, and IL-9 were upregulated. Injection of rHMGB1 into mice showed similar gene changes to 5xFAD mice exposed to O3, along with impaired Trem2 expression. Using a peripheral myeloid specific knock-out model of HMGB1, we also show that HMGB1 regulates O3-induced Trem2 expression impairment. Taken together, these data support that air pollution exposure impairs TREM2, DAM cells, and the microglial plaque response through a bidirectional lung-brain axis to exacerbate AD-like pathology.

No description available.