Alzheimer Disease

Amyloid beta (Aβ), a byproduct of amyloid precursor protein, is constantly cleared from the CNS. Aβ kinetics are visualized using 18F-florbetapir PET imaging, typically analyzed through 2D coregistration with MRI or CT followed by visual evaluation. Aβ was thought to coexist in the white matter of both Alzheimer’s disease (AD; Aβ+) patients and cognitively unimpaired (CU; Aβ-) individuals. However, this coexistence is likely a misperception of 2D imaging. In this study, data science techniques were used to evaluate PET images, transforming Aβ imaging into topographical pixel arrays for 3D reconstruction. Canal-like networks in the brain, skull, and neck were discovered to be part of the non-CNS fluid (NCF) compartment, which quarantines Aβ. In CU/Aβ- subjects, Aβ is transported to peripheral lymphatics. In AD/Aβ+ subjects, Aβ becomes congested in the NCF, diffusing into CNS interstitial fluid, leading to progression and neurodegeneration.

Alzheimer’s disease (AD) is one of the most common neurodegenerative diseases affecting an estimated 20 million worldwide. The primary pathology of AD is the progressive loss of basal forebrain cholinergic neurons, which is responsible for the cognitive decline experienced by AD patients. The mechanisms underlying this selective vulnerability have not been fully elucidated. Furthermore, oxidative stress is a key factor behind the pathology of AD leading to this neuronal loss. The current literature suggests that there are limited in-vitro models available to accurately simulate the hallmark symptoms of Alzheimer's disease (AD). The SH-SY5Y cell line has been used extensively to study neuronal stress responses but the undifferentiated cell type has been predominantly used. Undifferentiated SH-SY5Y versus differentiated SH-SY5Y have been shown to have different interaction, expression and localization with AD hallmark, amyloid-b -42. This project sought to use differentiated cholinergic cells from the line SH-SY5Y to further isolate and elucidate, in-vitro, the mechanisms behind the oxidative stress response, a key stressor in the pathology of AD. Building upon previous studies, a protocol to differentiate SH-SY5Y cells with retinoic acid (RA) and neurotrophin (BDNF) to mature neurons of the cholinergic phenotype was optimized and implemented. The results showed successful differentiation into the cholinergic phenotype as evidenced via immunofluorescence imaging of choline acetyl transferase (ChAT) expression and mature neurite morphology. To simulate oxidative stress, we exposed both undifferentiated and differentiated SH-SY5Y cells to hypoxic conditions. Results indicated a stress response to mild hypoxic conditions with higher sensitivity in cholinergic differentiated SH-SY5Y. Understanding these hallmark mechanisms behind oxidative stress is crucial to developing mechanism-based therapeutics for AD.

There are two types of stigmas: self-stigma and public stigma. The focus of this dissertation was public stigma. The public stigma encountered by persons with Alzheimer’s Disease (AD) contributes to the isolation of families due to the effort made by AD caregivers to adjust to social challenges (Abojabel & Warner, 2019). According to the Saudi Alzheimer’s Disease Association (2022), there are 130 thousand documented cases of AD, which comprised 9% of the aged population. The severity of stigmas can vary across cultures because stigmas of disease are connected to cultural norms (Corrigan, 2014). Most studies conducted in Saudi Arabia have assessed public stigma regarding mental illnesses, but no study has been found regarding public stigma within the AD scope. Population-based approaches that attempt to clarify stigma level prevalence in representative samples are important to develop methods to address these disparities and ensure equitable access to health care within the population's cultural context.
The aim of this study was to 1) identify the relationship between public stigma and the level of AD knowledge among the Saudi population and 2) identify the potential factors that were associated with public stigma and AD knowledge levels among Saudi community members, within the context of a caring science perspective using critical caring theory and specific-situation theory.

Alzheimer’s disease is a neurodegenerative disease that causes cognitive dysfunction and leads to progressive memory loss and behavioral impairment. About 60% to 80% of dementia cases are attributed to Alzheimer’s disease and currently afflict about 50 million people worldwide. Although it primarily affects people over the age of 65, a person’s risk for developing Alzheimer’s disease earlier can depend on factors such as a family history (genetic inheritance) or experiencing an ischemic stroke event. Current treatments for Alzheimer’s disease include behavioral therapy and drug treatment that can lessen the severity of symptoms but cannot stop progression indefinitely. Sulindac is a non-steroidal anti-inflammatory drug that, by a mechanism independent of its anti-inflammatory properties, has shown to express a preconditioning response to protect from oxidative damage. Granulocyte colony stimulating factor is a hematopoietic glycoprotein that can stimulate the production of granulocytes and stem cells that has proven to provide neuroprotection in models of ischemic stroke via mechanisms including anti-apoptosis and anti-inflammation. In this in vitro study, the potential neuroprotective effects of Sulindac is measured against the effects of oxidative stress when subjected to hypoxia and reperfusion. Regarding un-transfected SHSY-5Y cells, hypoxia was demonstrated to lower cell viability starting at a period of 12 hours. It was found that a low concentration of Sulindac (200 uM) was effective in protecting SHSY-5Y cells against oxidative stress and overall lowering the rate of cell death in the event of hypoxic and reperfusion injury. When SHSY-5Y cells were transfected with Swedish APP mutation, cell viability was also markedly decreased in hypoxic conditions. However when treated with a concentration of 600 uM of Sulindac, cell viability levels were near matched with its normoxic counterparts

Objective: Our main objectives were to identify cognitive markers of progression to a more severe cognitive diagnosis, explore possible differences between ethnic groups and to correlate cognitive markers of progression with biomarkers of AD (hippocampal and entorhinal volumes) and frontal volumes (lateral orbitofrontal, medial orbitofrontal, superior frontal, and rostral middle frontal volumes). Method: 207 participants (Mage = 71.79, SD = 7.48, 123 Hispanic Americans [HA]) were followed for an average of 23 months. Participants were classified into 3 diagnostic groups (Cognitively normal [CN], mild cognitive impairment [MCI], or dementia) based on the CDR global score and the neuropsychological baseline data was used as predictors of progression status. For the CN group, the Benson Figure delayed recall was a predictor of cognitive decline, and within the MCI group, the Benson delayed recall, the HVLT immediate recall, the TMTB, category fluency, and three measures of the LASSI-L (A1 cued recall, A2 cued recall, and delayed recall) were significant predictors of progression to dementia and are suggested as cognitive markers of progression for MCI individuals. Memory cognitive markers and category fluency correlated with medial temporal lobe volumes, and the TMT-B correlated with superior frontal volume. We did not observe significant differences in cognitive markers across ethnic groups. Conclusion: we identified cognitive markers of progression for CN and for MCI diagnoses which were not different across ethnic groups. These findings contribute to literature on the early identification of individuals at risk of progression to a more severe cognitive status even within asymptomatic individuals which can facilitate a more time- and cost-effective practice that is essential to the provision of the appropriate treatment to those at higher risk of progression.

Glycosylation is a frequent and heterogeneous post-translational protein modification occurring in all domains of life. Aberrant cell-surface glycosylation is shown to mediate several processes involved in tumor cell proliferation, adhesion, and metastasis. Recent findings linked altered protein glycosylation to Alzheimer’s disease (AD) pathogenesis. One key obstacle in studying functional consequences of glycosylation has been the lack of structurally defined glycopeptide or protein model compounds for biochemical studies at the molecular level. For tumor progression, studies are crucial towards understanding the glycan-lectin recognition process tied to deciphering the information contained in glycan structures and for AD, foundational studies are necessary for understanding the role of O-glycosylation in protein processing and its fate toward the amyloid pathway. In chapter 1, a highly O-glycosylated transmembrane and cancer-associated mucin protein, MUC1, is used as a model for designing synthetic tools for exploring its role in metastasis via association with lectins and specificity of anti-MUC1 antibodies. This dissertation for the first time presents a MUC1-based positional scanning synthetic glycopeptide combinatorial library that varies in the number and location of tumor-associated Tn antigen. The importance of defined structural complexity for evaluating glycan density and glycosylation patterns for binding to Tn-specific plant lectins and anti-MUC1 (mouse) monoclonal antibodies was revealed using an enzyme-linked lectin assay (ELLA). Chapter 2 addressed the growing significance of peptide lectinomimics for recognizing tumor-specific glycans. Fluorescently labelled alanine scan analogues of odorranalectin (OL), a cyclic peptide that exhibits lectin like properties, were screened for binding BSA-conjugated monosaccharides using ELLA. Results revealed that Lys5, Phe7, Tyr9, Gly12, Leu14, and Thr17 were crucial for binding BSA-L-fucose, BSA-Dgalactose and BSA-N-acetyl-D-galactosamine. The thermodynamics of binding of the selected alanine analogues was evaluated by isothermal titration calorimetry. The thermodynamic profile of interactions with asialofetuin exhibits shift to an entropy-driven mechanism compared to fucoidan, which displayed an enthalpy-entropy compensation, typically associated with the carbohydrate-lectin recognition process. Chapter 3 focused on amyloid-precursor protein (APP) O-glycosylation and its role in AD pathogenesis. We synthesized native and Swedish-mutated (glyco)peptides with O-GalNAc moiety on Thr663 and/or Ser667 or Tyr681 to explore the role of glycosylation on conformation, secretase activity, and aggregation kinetics of Aβ40. Our results show that conformation is strongly dependent on external conditions such as buffer ions and solvent polarity as well as internal modifications of (glyco)peptides such as length, O-glycosylation, and Swedish mutation (Lys670Asn/Met671Leu). Furthermore, the level of β-secretase activity significantly increased for the glycopeptides containing the Swedish mutation compared to their nonglycosylated and native counterparts. Lastly, glycopeptides impacted the kinetics of Aβ40 aggregation by significantly increasing the lag phase and delaying aggregation onset, however, this effect was less pronounced for its Swedish-mutated counterparts.

Unintentional weight loss in older adults often precedes Alzheimer’s disease (AD). Positron emission tomography (PET) scan reveals that AD patients exhibit reduced uptake of fluorodeoxyglucose into brain cells, defined as ‘hypometabolism’. However, cellular mechanisms underlying weight loss and hypometabolism have not received much attention. The primary goal of the study was to test the hypothesis that cells become starved in confrontation with amyloid beta proteins (Aβ), which are increasingly aggregated in the AD brain. Cellular ATP is known as a biomarker indicating for cell starvation. We found that Aβ caused a dose-dependent reduction in ATP of astrocytes. This effect was similar to those of cells being deprived from nutrients (i.e., glucose, pyruvate and glutamine). Together, the data of the present study support the hypothesis that cell starvation is likely associated with weight loss and hypometabolism in AD patients.