Saudi Cultural Missions Theses & Dissertations
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Item Restricted Oxytocin Attenuates Amyloid Beta Induced Oxidative Stress and Apoptosis in Hippocampal Neurons Through Nrf2 Activation(Saudi Digital Library, 2026) Alshehri, Mamdouh Salman; Castejon, Ana MBackground: Alzheimer's disease (AD) is the leading cause of dementia worldwide, classically characterized by extracellular amyloid-beta plaques and intracellular neurofibrillary tangles composed of hyperphosphorylated tau protein. Beyond these hallmark lesions, amyloid-beta 1-42 (Aβ1-42) oligomers drive progressive hippocampal neuronal loss through three interconnected downstream pathological processes: failure of the nuclear factor erythroid 2-related factor 2 (Nrf2)-mediated antioxidant defense system, neuroinflammation through the nuclear factor kappa B (NF- κB) and NLRP3 inflammasome pathways, and intrinsic apoptotic neuronal death through the p53/Bcl-2/Bax/caspase-3/PARP-1 cascade. Despite decades of research, no approved therapy has successfully halted or reversed AD progression; however, the recently approved anti-amyloid treatments lecanemab and donanemab have demonstrated modest slowing of clinical decline in early AD, although they target only one component of the complex disease process. Oxytocin (OXT) is a hypothalamic neuropeptide with documented neuroprotective properties, including anti-apoptotic, antioxidant, and anti- inflammatory effects mediated through the oxytocin receptor (OTR). OTR-mediated signaling through PI3K/Akt and protein kinase C (PKC) pathways are established upstream activators of Nrf2 nuclear translocation, raising the possibility that OXT may orchestrate a coordinated multi-target neuroprotective response through a single receptor. However, this OTR-Nrf2 connection had never been directly examined in Aβ1-42-exposed hippocampal neurons, and no published studies had previously investigated Nrf2 signaling in the CLU196 (mHippoE-2) hippocampal cell line. Objective: Our main goal was to investigate the effect of OXT on Aβ1-42-induced neuropathological changes in hippocampal neurons, including apoptotic signaling, oxidative stress, and neuroinflammation, and to determine whether these effects are mediated through OTR-dependent activation of the Nrf2 antioxidant pathway. Methodology: We used the CLU196 (mHippoE-2) immortalized mouse hippocampal neuronal cell line as our experimental model. Cells were exposed to Aβ1-42 to establish a pathophysiologically relevant hippocampal neuronal injury model. OXT was administered as a pretreatment prior to Aβ1-42 exposure, and the selective oxytocin receptor antagonist OXTA (L-368,899) was co-administered to determine whether the observed effects were mediated specifically through OTR. Cell viability was first evaluated by an MTT assay to establish the dose-response relationship and confirm Aβ1-42-induced cytotoxicity. Gene expression of Nrf2, apoptotic markers (p53, Bcl-2, Bax, caspase-3, and PARP-1), antioxidant enzyme genes (SOD-1, catalase, GPx-1, and HO-1), and neuroinflammatory markers (NF-κB, NLRP3, IL-1β, IL-6, and TNF-α) were then assessed by RT-qPCR. Intracellular reactive oxygen species (ROS) were subsequently quantified using the DCFDA fluorescence assay. Finally, protein expression of Nrf2, Bcl-2, and Bax was validated by Western blotting. Statistical comparisons were performed using one-way ANOVA with Tukey's multiple comparisons test. Results: The MTT assay confirmed that Aβ1-42 exposure significantly reduced cell viability in a dose-dependent manner, and OXT pretreatment significantly restored viability. These effects were absent in the presence of OXTA. RT-qPCR revealed that Aβ1- 42 exposure significantly suppressed Nrf2 mRNA expression alongside the Nrf2-regulated antioxidant enzymes catalase, GPx-1, and HO-1, while significantly upregulating the pro- apoptotic markers p53, Bax, caspase-3, and PARP-1 and downregulating the anti-apoptotic protein Bcl-2. OXT pretreatment significantly reversed all these gene expression changes, and these effects were abolished in the presence of OXTA. SOD-1 showed a less consistent response than the other antioxidant enzymes and is interpreted as a partial rather than a robust effect. RT-qPCR for neuroinflammatory targets yielded undetectable transcript levels across all treatment groups, consistent with the pure neuronal composition of CLU196 cells, which lack the glial cell populations required for neuroinflammatory gene expression. DCFDA assay demonstrated that Aβ1-42 exposure significantly elevated intracellular ROS, which were significantly reduced by OXT pretreatment. The OTR- specificity of this antioxidant effect was supported by the consistent reversal of Nrf2 and antioxidant enzyme gene expression by OXTA in the paired RT-qPCR experiments. Western blotting confirmed directional protein-level changes in Nrf2, Bcl-2, and Bax consistent with the RT-qPCR findings, and all protein changes were reversed when OXTA was present. Conclusion: Our results indicate that OXT activates the Nrf2/ARE antioxidant pathway in Aβ1-42-exposed hippocampal neurons and simultaneously reverses Aβ1-42- induced apoptotic gene dysregulation through OTR, as all protective effects were lacking in the presence of OXTA. This represents the first direct mechanistic evidence for an OTR- Nrf2 neuroprotective axis in a hippocampal Alzheimer's disease model and the first investigation of Nrf2 signaling in the CLU196 (mHippoE-2) cell line. Furthermore, these findings identify OXT as a candidate multi-target neuroprotective agent capable of addressing both antioxidant defense failure and apoptotic neuronal death through a single receptor system. These results contribute to a better understanding of OXT's potential as a neuroprotective strategy in early Alzheimer's disease.9 0Item Restricted A Computational Platform for Mining Failed Multi-Kinase Inhibitors: Transforming Off-Target Liabilities into Experimentally Testable Hypotheses through AI-Driven Drug Discovery(Saudi Digital Library, 2026) Basalelah, Lama; Dayanjan, S WijesingheMore than ninety percent of multi-kinase inhibitor programs fail in clinical development, most often from off-target toxicity, yet the discontinued compounds, and the rich pharmacological data they carry, are rarely reused. This dissertation presents an integrated, open computational platform that mines failed multi-kinase inhibitors and reframes their off-target binding profiles from liabilities into experimentally testable repurposing hypotheses. Using CDK7 (ChEMBL CHEMBL3055) as a case study, the platform demonstrated that clinical failure tracks engagement of cancer-essential kinases rather than raw promiscuity, translated this distinction into a Repurposing Readiness Score and an A/B/C triage, and applied a fragment-based genetic algorithm to generate novel chemotypes with a predicted, ordinal reduction in CDK7 binding, supported concordantly by XGBoost IC50 prediction and molecular docking. Preliminary transferability was demonstrated for GSK3B in Alzheimer's disease. All results are computational predictions requiring experimental validation; the platform's contribution is a transparent decision-support framework that prioritizes discontinued kinase inhibitors as testable repurposing hypotheses rather than finished therapeutics.11 0Item Restricted DRUG REPURPOSING OF RAPAMYCIN MITIGATES AMYLOID BETA ASSOCIATED PROTEOTOXICITY IN CAENORHABDITIS ELEGANS(Saudi Digital Library, 2026) Alkhudydi, Samirah; Moreno,J ulieAlzheimer's disease (AD) is the leading cause of dementia worldwide, affecting an estimated 55 million people and projected to exceed 130 million by 2050. Defined neuropathologically by the extracellular accumulation of amyloid-beta (Aβ) peptides and intracellular neurofibrillary tangles of hyperphosphorylated tau, AD currently lacks disease-modifying therapies capable of halting or reversing neurodegeneration. The proteotoxic accumulation of Aβ is a central pathogenic event, and strategies that enhance endogenous clearance mechanisms represent a compelling therapeutic area. Rapamycin (sirolimus), a macrolide allosteric inhibitor of the mechanistic target of rapamycin complex 1 (mTORC1), is one of the most robustly validated pharmacological extenders of lifespan across model organisms and has demonstrated neuroprotective potential in mammalian AD models. Its capacity to provide mTORC1-mediated suppression of autophagy and to reduce neuroinflammation positions it as an attractive drug-repurposing candidate for AD. However, the extent to which rapamycin can mitigate Aβ proteotoxicity in Caenorhabditis elegans remains unexplored, and leveraging this model organism offers a powerful opportunity to study the mechanism by which rapamycin-mediated mTOR inhibition interacts with amyloid-β aggregation, clearance pathways, and proteostasis in the context of Alzheimer's-related neurodegeneration. In this study, we used two well-established transgenic Caenorhabditis elegans models of Aβ proteotoxicity: the muscle-specific temperature-inducible strain CL4176 (Pmyo-3::Aβ₁₋₄₂) and the pan-neuronal strain CL2355 (Psnb-1::Aβ₁₋₄₂). Following an empirical dose-finding strategy across four sequential titration experiments, 20 μM rapamycin was selected as the working concentration. Rapamycin treatment (20 μM) significantly delayed Aβ-induced paralysis in CL4176 animals, extending the time that 50% of the population was paralyzed (PT50) by approximately 1.8 hours (~23% relative to vehicle; log-rank p = 0.0017). Automated locomotion analysis further demonstrated that rapamycin improved peristaltic speed, center-point speed, and wavelength while markedly reducing mobility idle time (p < 0.05 to p < 0.0001). Swimming parameters as wave initiation rate, swimming speed, dynamic amplitude, and wave attenuation were similarly improved, collectively indicating a broad restoration of neuromuscular function. In the panneuronal CL2355 strain, rapamycin significantly rescued the Aβ-induced chemotaxis deficit, restoring the chemotaxis index toward control strain levels (one-way ANOVA, p = 0.015) without altering behavior in the non-transgenic CL2122 control. Kaplan–Meier lifespan analysis revealed that rapamycin significantly extended survival in CL2355 animals (log-rank, Bonferroni-adjusted p < 0.0001, with the most pronounced effect observed in the Aβ-expressing strain. Combined survival–locomotion analysis further demonstrated that rapamycin preserved neuromuscular healthspan, delaying the onset of age-related motor decline relative to vehicle-treated Aβ animals. At the molecular level, Western blot analysis using anti-Aβ immunoblotting revealed that rapamycin selectively reduced the accumulation of higher-molecular-weight Aβ oligomeric species (25 kDa and 60 kDa; p < 0.05 each), while monomeric and lower oligomeric Aβ levels were not significantly altered. Taken together, these findings demonstrate that rapamycin confers consistent, broad-spectrum neuroprotection across orthogonal measures of Aβ proteotoxicity in C. elegans, extending from acute paralysis and locomotion to chemosensory behavior, longevity, and healthspan. The selectivity of rescue in Aβ-expressing animals supports a mechanism engaged with proteotoxic pathology. These results establish C. elegans as a tractable platform for evaluating mTOR-directed therapies and strengthen the rationale for further preclinical investigation of rapamycin as a disease-modifying strategy in Alzheimer's disease.11 0Item Restricted Pharmacological Evaluation of the cPLA2 Inhibitor, BRI-50460, in Neuroinflammation(Saudi Digital Library, 2026) Alshammari, Maram; Louie, StanAlzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by chronic microglial-driven neuroinflammation, amyloid-β accumulation, and synaptic loss. Cytosolic phospholipase A2 alpha (cPLA2α) is a central mediator of this inflammatory cascade, liberating arachidonic acid from membrane phospholipids and driving downstream eicosanoid and oxylipin production. Despite its therapeutic relevance, selective cPLA2α inhibitors have failed to reach clinical use due to limitations in CNS penetrance, selectivity and pharmacokinetic stability. BRI- 50460 is a novel indole-based cPLA2α inhibitor with demonstrated oral bioavailability and brain exposure. This thesis describes the preclinical characterization of BRI-50460 across four experimental domains: formulation development, cytotoxicity assessment, lipidomic profiling, and gene expression analysis in LPS-activated BV2 murine and HMC-3 human microglial cell models. BRI-50460 demonstrated no cytotoxicity across all the tested cell lines. Lipidomic profiling revealed that BRI-50460 pre-treatment redirected arachidonic acid metabolism away from pro- inflammatory eicosanoids and elevated pro-resolving mediator production. RT-qPCR profiling further demonstrated transcriptional suppression of PLA2g4a and PTGS consistent with on- target cPLA2α inhibition, directional increase in CMKLR1 under BRI-50460 alone, and modulation of ALOX5 and CYP2J9, which collectively, support a pro-resolving shift in microglia lipid signaling. Collectively, these findings establish BRI-50460 as a promising cPLA2α inhibitor with the potential to redirect microglial neuroinflammation toward resolution, providing a preclinical foundation for future in vivo investigation in Alzheimer's disease.15 0Item Restricted The Relationship Between Stigma and Level of Alzheimer's Disease Knowledge Within The Saudi Culture(Saudi Digital Library, 2023-11-30) Jambi, Amnah; Butcher, Howard KarlThere 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. A non-experimental, correlational descriptive, and cross-sectional design was used for this study. The method of collecting data was an online survey method (Qualtrics) using the Basic Knowledge of Alzheimer's Disease (BKAD) to measure knowledge (Wiese, et al., 2017, 2019), and an adapted version of the Attribution Questionnaire AQ-9 to measure public stigma (Kim et al., 2021; Werner et al., 2017). Data analysis was performed via SPSS version 29. A total of (N = 150) participants were recruited in a span of three months. Data analysis revealed: 1) a significant correlation (r = -.20, p = .016) between AD knowledge and public stigma level, 2) significant factors associated with public stigma level were gender (B = 1.89, t = 2.51, p = .013), an education level (B = -2.69, t = -3.42, p < .001); and experience as an AD caregiver professionally (B = 2.69, t = 2.30, p = .023), 3) Factors significantly associated with AD knowledge level were the a) age group 18- 24 years old (B = 2.78, t = 2.27, p = .025), b) occupation in the non-medical profession category (B = -1.77, t = -2.04, p = .043), and c) education level (B = 2.27, t = 2.75, p = .007). Stigma can vary based on various contextual factors, including cultural influences, in which further studies are needed to better understand the concept in versatile cultures. The findings provided valuable insights into the patterns and significance of relationships between public stigma, AD knowledge, and factors associated with stigma and AD knowledge.45 0Item Restricted Exploring potential glial senescence signatures in Alzheimer’s disease(Saudi Digital Library, 2023-11-01) Allehyany, Bshaier; Matthews, PaulBackground: Glial cells’ ability to maintain homeostasis in the brain and regulate neuroinflammation is altered in Alzheimer’s disease. Senescent glia – glia with irreversible cell cycle arrest, resistance to apoptosis, and pro-inflammatory cytokine secretion – are associated with exacerbated amyloid-β and tau pathology. GLB1 is widely associated with predicting glial senescence in ageing. Aims, objectives, and hypothesis: Using imaging mass cytometry data, we aimed to quantify microglia and astrocytes and identify their potential senescence signatures. We hypothesized that a glial senescence signature, predicted by GLB1 co-expression, exists in AD. Methods: Using in-house-generated imaging mass cytometry data from the mid-temporal gyrus of post-mortem brain tissue, cell counts of Iba-1-positive microglia and GFAP-positive astrocytes were determined in AD and control cases. The expression of senescence markers, and the co-expression of GLB1 in senescence-expressing glia were investigated. Independent sample t-tests with an FDR correction were used for between-group comparisons (or the Mann–Whitney U test if data failed the normality test). Results: There was no significant difference between groups in Iba-1-positive microglia and GFAP-positive astrocyte counts. Iba-1-positive microglia did not show a senescence signature, while GFAP-positive astrocytes showed increased senescence expression in p21, γ-H2AX, and GLB1. Cells positive for GLB1 and other senescence markers only showed a significant increase in GFAP-positive astrocytes. Conclusions and future directions: Reactive astrocytes were associated with a GLB1- associated senescence signature in Alzheimer’s disease, whereas microglia were not. This senescence-like phenotype may suggest the vulnerability of reactive glia to oxidative stress and DNA damage. This work highlights the possibility of targeting GLB1-expressing reactive astrocytes for senescent cell-eliminating drugs – senolytics.13 0Item Restricted YKL-40 PREDICTS TEMPOROPARIETAL GLUCOSE HYPOMETABOLISM AND Aβ DEPOSITION IN ALZHEIMER’S DISEASE TRAJECTORY(Saudi Digital Library, 2023-11-01) Allehyany, Bshaier; Edison, PaulAlzheimer’s disease (AD) biomarkers amyloid-β and tau aggregates have not been effective AD therapeutics, and it is important to investigate other biomarkers for AD to identify novel therapeutic targets that slow disease progression. Glial cell activation markers in the cerebrospinal fluid have recently been associated with AD, especially the astroglial activation marker chitinase-3-like protein 1 (YKL-40) and the microglial activation marker soluble triggering receptor expressed on myeloid cells 2 (sTREM2). Another cerebrospinal fluid marker that has been recently associated with AD is the synaptic dysregulation marker growth associated protein 43 (GAP-43). Despite being associated with amyloid-β and tau pathology, the role of these biomarkers in AD-associated temporoparietal glucose hypometabolism and reductions in grey matter volume is still unclear. This study aimed to investigate the associations between cerebrospinal fluid YKL-40, sTREM2, and GAP-43 and brain glucose hypometabolism and reductions in grey matter volume. Participants (n = 385) were grouped into four conditions: AD, amyloid-positive mild cognitive impairment (MCI), amyloid-negative MCI, and controls. Regional analysis and voxel-level linear regression revealed that YKL-40 could predict temporoparietal glucose hypometabolism in amyloid-positive groups, and that GAP-43 is predictive of different patterns of hypometabolism in the AD group. Only sTREM2 and YKL-40 predicted reduced grey matter volume, but YKL-40 predicted earlier cognitive decline. YKL-40 may be more sensitive to earlier stages of cognitive decline in amyloid-positive participants than the other markers, possibly due to amyloid-induced neuroinflammation and neurodegeneration. However, correlational studies can only give indirect conclusions and future studies are needed to identify direct effects of neuroinflammation and synaptic loss on YKL-40 levels using cell cultures.8 0Item Restricted Role of Retinoic Acid Receptor β Signalling in Alzheimer’s Disease(Saudi Digital Library, 2023-08-27) Almuallim, Hassan Yousef Othman; Corcoran, JonathanAlzheimer's disease, the most common form of Dementia, is characterized by a debilitating progression of memory impairment and cognitive decline. The distinct neuropathological hallmarks characterizing Alzheimer's disease revolve around the existence of senile plaques containing amyloid-β, as well as neurofibrillary tangles composed of tau protein, precipitating oxidative stress and neuroinflammation. The therapeutic options for Alzheimer’s disease are either symptomatic treatments or disease-modifying drugs, with the latter currently showing significant investment in targeting amyloid-β. Interestingly, DNA double-strand breaks play a role in increasing the secretion of amyloid-β, consequently triggering the aggregation of amyloid-β plaques. However, there are currently no therapeutic options available for Alzheimer’s disease that specifically target the induction of DNA repair. KCL286, a synthetic retinoic acid receptor beta agonist with promising results from a phase I clinical trial, has demonstrated its capacity to initiate DNA repair mechanisms in a nerve injury model. In this context, we embarked upon an investigation into the effects of KCL286 administration in Tg2576 mice, a transgenic strain characterized by human amyloid precursor protein overexpression and consequently amyloid-β accumulation. A three-month treatment significantly reduced the DNA damage response protein γH2AX, in particular the gene expression of γH2AX within the hippocampus. The inducing of DNA double-strand break repair corresponded with the clearance of amyloid-β deposits and reduction in inflammation. The study underscores the potential of stimulating the RARβ signalling pathway via the RARβ agonist KCL286, as it appears to induce DNA repair mechanism and amyloid-β clearance. This reinforces the drug’s promise as a prospective therapeutic candidate for Alzheimer's disease.22 0Item Restricted The Effects of Iron and Inflammation on Alzheimer’s Disease in 5xFAD Mice(Saudi Digital Library, 2023-09-01) Aljuhani, Manal; So, Po-WahBoth neuroinflammation and iron dyshomeostasis feature in, and contribute to, Alzheimer’s disease (AD), and have been shown to interact synergistically. This thesis aims to investigate: 1) the short-term effect of peripheral iron administration on the progression of AD in 5xFAD and wildtype in both male and female mice and 2) the short/long term effects of peripheral iron administration, with and without inflammatory priming, on the progression of AD in 5xFAD and wildtype mice. A multimodality approach was used to assess the progression of AD: behavioural assessments to evaluate cognitive performance; in-vivo magnetic resonance imaging studies, relaxation rates R1 and R2, as putative indices of inflammation and iron accumulation, respectively; quantitative iron assessments and immunohistochemical assessments of both neuroinflammation and plaque deposition. Iron treatment led to increased numbers of plaques and microglia in the hippocampus accompanying cognitive impairment and higher levels of hippocampal iron in 5xFAD female mice. Conversely, 5xFAD male mice treated with iron demonstrated increased levels of plaque deposition, but cognitive impairment was not observed. Male and female mice had a differential response to iron treatment. In the short-term effect, hippocampal and cortical R1 were increased by lipopolysaccharide (LPS) treatment alone, and combined with iron, in wildtype mice. Moreover, microglial branch length and number of end points were higher in LPS and LPS + iron. Conversely, in 5xFAD mice, plaque deposition was increased post-iron and -LPS treatments in the hippocampus and cortex but reduced when the two treatments were combined (LPS+iron). In the long-term, hippocampal and cortical R2 were increased by LPS treatment in 5xFAD mice. Additionally, plaque deposition was higher by LPS, alone or combined with iron, along with an increase of iron concentration in the hippocampus. In the long term, R2 correlated with Aβ plaque deposition, and with iron content consistent with previous reports. I demonstrate sex- and region-dependent effects of peripheral inflammation and/or iron in 5xFAD mice and wildtype littermates. The data provides evidence for further study of iron dyshomeostasis and inflammation as potential therapeutic targets in AD.18 0