Exploring NOX2-Mediated Network Impairment and Neurodegeneration in Alzheimer's Disease - PROJECT SUMMARY The complexity and multifactorial nature of Alzheimer’s disease (AD) pose unique challenges for mechanistic studies and developing therapies. One of the earliest AD biomarkers is brain glucose hypometabolism associated with oxidative stress (OS), which occurs well before clinical symptoms manifest. Regional glucose hypometabolism correlates with cognitive and functional impairments in AD patients and is closely associated with accumulation of the pathological proteins A and hyperphosphorylated Tau. Epilepsy is a well-established early co-morbidity of AD, with the risk of seizures up to three times higher in AD patients compared to the general population, and seizure likelihood increases with AD progression and severity. Moreover, network hyperactivity in the form of subclinical seizures and interictal epileptiform activity is common in the preclinical and prodromal stages of AD and is associated with an accelerated cognitive decline. Reducing hippocampal hyperactivity with the antiepileptic drug levetiracetam improved cognition in amnestic mild cognitive impairment (MCI) patients and in AD mouse models, suggesting that network hyperactivity plays a role in AD-related cognitive dysfunction. Importantly, network hyperactivity is associated with A and Tau accumulation as well as with glucose hypometabolism and OS, suggesting a shared underlying mechanism driving these key AD pathologies. Development of a safe and effective unified strategy to counteract these primary pathologies holds a significant promise in advancing AD treatment. Our published and preliminary data show that the reactive oxygen species (ROS)-producing enzyme NAD(P)H oxidase 2 (NOX2) mediates multiple A- and Tau-induced network and metabolic dysfunctions, including network hyperactivity and glucose hypometabolism. Therefore, we propose that inhibition of NOX2 represents a potential multifactorial treatment strategy. For NOX2 inhibition, we propose a novel antagonist GSK2795039 with unique brain bioavailability and no toxicity at effective concentrations. We aim to fully assess GSK2795039 therapeutic efficacy in mitigating AD-related brain dysfunction, and to uncover the molecular mechanisms underpinning NOX2-mediated Aβ and Tau toxicities. To investigate GSK2795039’s potential to alleviate A-induced neuropathology, transcriptomic changes, and learning/memory deficits (Aim 1), we will use the APPNL–G–F mouse model, validating the GSK2795039 effect using APPNL–G–F mice crossed with NOX2-deficient (Cybb-/-) mice. To explore GSK2795039 effects on Tau-mediated pathologies (Aim 2), we will employ mice overexpressing P301S mutant tau (PS19), again confirming the effects in PS19 mice crossed with Cybb-/-mice. Finally, we will delve into the specific mechanisms of NOX2-mediated Aβ and Tau effects at the neuronal level, using Aβ and Tau application on ex-vivo brain slices from wild-type mice (Aim 3). The proposed project not only seeks to advance our understanding of AD but also to explore the feasibility of NOX2 inhibition as a viable and innovative treatment, reflecting a shift towards safer and more effective therapeutic strategies.
