In this study, we used resting-state functional magnetic resonance imaging (fMRI) scans from subjects with early mild cognitive impairment (EMCI) and control subjects to study functional network connectivity. The scans were acquired by the Alzheimer's Disease Neuroscience Initiative (ADNI). We used genetic data from the ADNI database to further subdivide the EMCI and control groups into genotype groups with or without the ApoE4 allele. ROI-to-ROI resting-state functional connectivity was measured using Freesurfer and the Functional Connectivity Toolbox for Matlab (CONN). In our analysis, we compared whole-brain ROI connectivity strength and ROI-to-ROI functional network connectivity strength between EMCI, control and genotype subject groups. We found that the ROI network properties were disrupted in EMCI and ApoE4-containing groups. Notably, we show that (1) EMCI disrupts functional connectivity strength in many areas; (2) the ApoE4 allele disrupts functional connectivity strength in similar areas to EMCI; and (3) the differences in functional connectivity between groups shows a multifactor contribution to functional network dysfunction along the trajectory leading to dementia.

Alzheimer’s disease (AD) is a neurodegenerative disease with characteristic amyloid, neurofibrillary tangles, and neuronal death in the brain. The major component of amyloid is monomeric amyloid beta (Aβ) protein, as well as its oligomers and large fibrils. Aβ, especially oligomeric Aβ, causes neurotoxicity. The aim of the present study was to investigate how Aβ is metabolized in the presence of microglia cells. We have used a cellular model to study the phagocytosis and degradation of Aβ by BV-2, a murine microglia cell line. We also examined if amylin, a pancreatic peptide, influences the metabolism of Aβ by BV-2 cells. Through Western blot analysis, we observed the phagocytosis of Aβ by BV-2 cells. In our investigation of the role of amylin, we observed a trend in our finding that amylin increased phagocytosis in BV-2 cells and decreased aggregation in the culture medium. Our data demonstrate that amylin may modulate microglia function in the AD brain and has potential to become therapeutic for the disease.

Boston University. University Professors Program Senior theses. / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / 2031-01-02

People with Down’s syndrome (DS) are known to experience premature ageing and have a high propensity for clinical diagnosis of dementia due to Alzheimer’s disease (AD). In DS there is a unique and natural model of over-expression of amyloid-beta (Aβ) protein, the accumulation of which is proposed to be the central early event in the pathogenesis of AD. In DS, AD neuropathology is universally seen in the brain from the fourth decade. Identifying biomarkers are essential to the evaluation of future treatment trials. The retina has been shown to experience changes in patients with AD, such as retinal thinning, compared to age-matched controls. As an extension of the brain, the retina can be quickly and non-invasively imaged and may provide a proxy measure of brain changes in AD. Using optical coherence tomography (OCT), cross-sectional retinal examinations were completed in 50 people with DS aged 18 years and over. Comparisons between retinal thickness of the DS and control groups were examined, as well as the effect of age on thickness in both groups. For the DS group, further investigations were made into the relationships between retinal thickness and (i) cognitive performance, (ii) diagnosis of dementia, (iii) cortical thickness and, (iv) presence of Aβ binding in the brain. Contrary to expectations, people with DS had thicker retina compared to age-matched controls. In addition, normal age-related retinal thinning was not seen in the DS group. People with DS have a life-long overproduction of Aβ, deposits of which have been previously imaged in the retina. Aβ may be responsible both directly, through physical mass, and indirectly through inflammation as a response to Aβ, for increased retinal thickness in people with DS. Consequently, retinal thickness in DS may be a proxy measure of Aβ deposition in the retina. As part of a collaborative study, brain Aβ binding was measured using positron emission tomography neuroimaging in a subset of the DS group. Individuals with positive Pittsburgh compound [11C]-PIB (PIB) binding to Aβ displayed a trend towards having thinner retina than those with negative PIB binding. These results indicate that a shift towards thinning retina in people DS may reflect changes in brain pathology. Future studies are discussed which aim to investigate Aβ and Aβ driven pathology in the retina.

Alzheimer’s disease (AD) is the most common cause of dementia, affecting almost 40 million people worldwide, and it is predicted that this number will rise to nearly 150 million by 2050. It results not only in enormous distress for affected individuals and carers but also a substantial economic burden on society. Although more than 100 years have passed since its discovery, no cure for AD exists, despite enormous efforts in basic and clinical research over the past few decades, due to limited understanding of its underlying mechanisms. Neurodegenerative disorders, of which AD is an example, are highly complex disorders characterized by extensive neuronal dysfunction associated with the misfolding and aggregation of a specific set of proteins, including amyloid plaques and neurofibrillary tangles in AD. One promising avenue for progress in the field is to improve our understanding of the mechanisms by which cellular dysfunction arises from the initial protein aggregation events. The studies described in the thesis are based on the recent finding that a large number of proteins are inherently supersaturated, being expressed at concentrations higher than their solubilities, and constituting a metastable subproteome potentially susceptible to aggregation. These studies illustrate the dependence of aggregation prone metastable proteins on the cellular degradation machineries. They also study the role of metastable proteins and their homeostasis complement in the vulnerability of various body and brain tissues to protein aggregation diseases. Using extensive sequencing data and network based systems biology approaches, they elucidate how fundamental physicochemical properties of an individual or group of proteins relate to their biological function or dysfunction.

abstract: The goal of this thesis is to test whether Alzheimer's disease (AD) is associated with distinctive humoral immune changes that can be detected in plasma and tracked across time. This is relevant because AD is the principal cause of dementia, and yet, no specific diagnostic tests are universally employed in clinical practice to predict, diagnose or monitor disease progression. In particular, I describe herein a proteomic platform developed at the Center for Innovations in Medicine (CIM) consisting of a slide with 10.000 random-sequence peptides printed on its surface, which is used as the solid phase of an immunoassay where antibodies of interest are allowed to react and subsequently detected with a labeled secondary antibody. The pattern of antibody binding to the microarray is unique for each individual animal or person. This thesis will evaluate the versatility of the microarray platform and how it can be used to detect and characterize the binding patterns of antibodies relevant to the pathophysiology of AD as well as the plasma samples of animal models of AD and elderly humans with or without dementia. My specific aims were to evaluate the emergence and stability of immunosignature in mice with cerebral amyloidosis, and characterize the immunosignature of humans with AD. Plasma samples from APPswe/PSEN1-dE9 transgenic mice were evaluated longitudinally from 2 to 15 months of age to compare the evolving immunosignature with non-transgenic control mice. Immunological variation across different time-points was assessed, with particular emphasis on time of emergence of a characteristic pattern. In addition, plasma samples from AD patients and age-matched individuals without dementia were assayed on the peptide microarray and binding patterns were compared. It is hoped that these experiments will be the basis for a larger study of the diagnostic merits of the microarray-based immunoassay in dementia clinics. / Dissertation/Thesis / Ph.D. Molecular and Cellular Biology 2011

Infections are a common co-morbidity in Alzheimer's disease (AD), and evidence suggests that infections can exacerbate neuroinflammation and increase cognitive decline in AD patients. In AD, immune changes are observed both in the central nervous system (CNS) and in the rest of the body. However, only a few studies have investigated immune responses to infection in AD. Here, two extensively studied infections, Toxoplasma gondii (T. gondii) and Trichuris muris (T. muris) were used to investigate infection in AD. T. gondii is a protozoan parasite which is common globally, including in the developed world where AD cases are increasing dramatically. Infection with T. gondii starts in the gut, before becoming systemic and then infecting the CNS, where the parasite forms a chronic cyst infection. In contrast, T. muris is a nematode parasite, which remains localised to the gut. Notably, T. gondii is known to alter neuroinflammation and behaviour. T. gondii forms cysts preferentially in the areas of the brain commonly affected by AD, such as the hippocampus, which therefore makes it an interesting model to study co-morbidity. AD is often associated with advanced age. As we age, our immune system declines, and an important unanswered question is whether age impacts on the immune response to infection. This is of particular significance when considering chronic infections such as T. gondii, which require immune surveillance to prevent parasite recrudescence. Therefore, the aim of this thesis was to investigate infection in AD by determining: whether the immune response to an infection is altered in AD; whether the immune response to an infection in AD differs with age; what the effects of infection are on neuroinflammation, pathology and behaviour in AD; what are the effects of chronic infection with T. gondii. Immune responses to infection were altered in both the 3xTg-AD and the APP PS1 mouse models of AD, including increased inflammation and weight loss in AD mice following infection. Although older (eleven to twelve-month-old) 3xTg-AD mice showed some alterations in cytokine responses following infection, overall there were no major difference compared to younger (five to six-month-old) animals. Additionally, infection was found to alter neuroinflammation in both 3xTg-AD and APP PS1 mice, though differently. In 3xTg-AD mice, microglia activation increased following infection with T. gondii and T. muris, showing that infection did not need to be in the brain to alter neuroinflammation. In APP PS1 mice, a decrease in microglia activation occurred after infection with T. gondii, which was accompanied by an increase in IL-1alpha production and increased amyloid beta levels in APP PS1 mice following infection. However, no changes were found in behaviour following infection with T. gondii or T. muris in AD mouse models. Finally, chronic T. gondii infection was investigated in the TgF344-AD rat, which was established as a suitable AD model with both amyloid and tau pathology in which to study chronic infection. This work adds to a growing body of literature to suggest that infections are detrimental to AD patients, and that future measures to decrease morbidity could focus on further study of infections in AD, and the development of strategies to better prevent infections in AD patients.

Alzheimer's disease (AD) is the most common cause of dementia; a problem that is growing in size and cost as the population ages. Early soluble aggregates composed misfolded 'amyloid' peptide sequences have been implicated as key to the initiation and onset of AD pathology, although little is definitively known as to when and how these assemblies form or interact to instigate pathology. The primary focus of this study was to evaluate whether L-Tryptophanol (Trol) signal, which has been shown to be induced via soluble amyloid species, increases with AD severity in a range of ex vivo human samples. Testing of this hypothesis was carried out in several stages: Initially synthetic versions of the amyloid beta (Aβ) peptide were tested in vitro to corroborate Trols propensity to associate to amyloid assemblies and allow for method development. Next, a range of brain lysates from several transgenic mouse lines and aged human AD cases and controls were assessed using the reporter. These experiments demonstrated Trols sensitivity to Aβ and tau, and provided compelling evidence that Trol signal tracks disease progression in brain lysates. During the final stage of testing cerebrospinal fluid (CSF) from AD and Parkinson's disease (PD) patients, and blood plasma samples from PD patients was evaluated. Results from this phase of testing indicated that Trol was able to detect differences in sample composition between healthy and diseased individuals, however differences were not clear cut and could have been affected by confounding factors. Overall, the data presented here suggest that Trol may be able to track disease progression in amyloidopathies when implemented in brain lysates. However, further testing is required to completely validate this finding. These findings highlight the potential of simple techniques for amyloid detection to aid within the diagnosis, evaluation of disease progression and study of AD and other neurodegenerative diseases.

abstract: Vitamin D deficiency has been previously associated with a higher Alzheimer’s disease (AD) risk, a condition marked by dependent living and severe cognitive impairment. AD is histologically defined by the presence of brain amyloid beta (Aβ) plaques and neurofibrillary tangles. Ways to enhance Aβ clearance have been examined in order to sustain cognition and delay AD onset. In vitro and in vivo studies suggest that vitamin D might enhance brain Aβ transportation to the periphery by up-regulating P-glycoprotein production. The purpose of this study was to examine the effect of vitamin D supplementation on plasma Aβ in an older population. This study was a parallel-arm, double-blinded, randomized control trial. Participants consumed either a vitamin D supplement or placebo once a week for eight weeks (n=23). Only vitamin D insufficient (serum total 25-OH, D < 30 ng/mL) people were included in the study, and all participants were considered to be cognitively normal (MMSE scores > 27). Serum total 25-OH, D and plasma Aβ1-40 measurements were recorded before and after the eight-week trial. The plasma Aβ1-40 change was compared between the vitamin D group and control group. The vitamin D group experienced a 45% greater change in plasma Aβ1-40 than the control group. The effect size was 0.228 when controlling for baseline plasma Aβ1-40 (p=0.045), 0.197 when controlling for baseline plasma Aβ1-40 and baseline physical activity (p=0.085), and 0.179 when controlling for baseline plasma Aβ1-40, baseline physical activity, and age (p=0.116). In conclusion, vitamin D supplementation might increase brain Aβ clearance in humans, but physical activity and age also appear to modulate Aβ metabolism. / Dissertation/Thesis / Masters Thesis Nutrition 2015

abstract: Neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, or amyotrophic lateral sclerosis are defined by the loss of several types of neurons and glial cells within the central nervous system (CNS). Combatting these diseases requires a robust population of relevant cell types that can be employed in cell therapies, drug screening, or patient specific disease modeling. Human induced pluripotent stem cells (hiPSC)-derived neural progenitor cells (hNPCs) have the ability to self-renew indefinitely and differentiate into the various neuronal and glial cell types of the CNS. In order to realize the potential of hNPCs, it is necessary to develop a xeno-free scalable platform for effective expansion and differentiation. Previous work in the Brafman lab led to the engineering of a chemically defined substrate—vitronectin derived peptide (VDP), which allows for the long-term expansion and differentiation of hNPCs. In this work, we use this substrate as the basis for a microcarrier (MC)-based suspension culture system. Several independently derived hNPC lines were cultured on MCs for multiple passages as well as efficiently differentiated to neurons. Finally, this MC-based system was used in conjunction with a low shear rotating wall vessel (RWV) bioreactor for the integrated, large-scale expansion and neuronal differentiation of hNPCs. Finally, VDP was shown to support the differentiation of hNPCs into functional astrocytes. Overall, this fully defined and scalable biomanufacturing system will facilitate the generation of hNPCs and their derivatives in quantities necessary for basic and translational applications. / Dissertation/Thesis / Masters Thesis Biomedical Engineering 2018