Lipid metabolism, neuroinflammation, and oxidative stress in Alzheimer disease: an integrated mechanistic review.

Mitochondrial defects and oxidative stress in Alzheimer disease and Parkinson disease

Oxidative stress in Alzheimer's disease brain: New insights from redox proteomics

Alzheimer's disease: cerebrolysin and nanotechnology as a therapeutic strategy.

In the recent time, neurodegenerative disorders like Alzheimer disease were recognized for their significant role in the current healthcare because of their growing incidence and costs for health insurance systems. Effective therapy is missing and even etiology of the diseases like Alzheimer disease is not deeply known. In the case of Alzheimer disease, it is probable that oxidative stress is at least a factor involved in the disease. Nevertheless, the current literature is controversial and ambiguous in this matter. This review is focused on mapping the role of oxidative stress as well as on a consideration that oxidative stress represents the pathway at which a therapeutic strategy can be aimed. This paper provides a survey of contemporary literature on oxidative stress in Alzheimer disease and discusses the opportunities for establishing a therapy based on interfering the stress (Fig. 5, Ref. 117).

Increased Neuronal Glucose-6-phosphate Dehydrogenase and Sulfhydryl Levels Indicate Reductive Compensation to Oxidative Stress in Alzheimer Disease

Alzheimer's disease (AD) is the most prevalent neurodegenerative disease among older people. AD can cause memory loss and neuropsychiatric abnormalities. AD pathogenesis is complicated. Oxidative stress and chronic neuroinflammation are believed to contribute to the occurrence and progression of AD. Oxidative stress refers to a harmful state of neurons caused by an impaired antioxidant system and abnormal accumulation of reactive oxygen species (ROS) in the brain of a patient with AD. Neuroinflammation often results from a series of harmful responses to neurons induced by the overactivated microglia and astrocytes, such as the secretion of proinflammatory cytokines and promotion of neuronal apoptosis. Several studies have demonstrated that inhibition of oxidative stress and neuroinflammation can alleviate AD symptoms, suggesting that they may serve as potential targets for drug development. Herein, we review the mechanism of oxidative stress and neuroinflammation. Additionally, we have summarized data from preclinical studies published between 2019 and 2024 that investigate traditional Chinese medicine (TCM) formulations used to treat AD through the modulation of oxidative stress and neuroinflammation. We have included information on the extracts, compounds, modified compounds, and novel delivery systems for TCM formulations and summarized the key mechanisms involved in their actions.

Alzheimer's disease is the most common and lethal neurodegenerative disorder. The major hallmarks of Alzheimer's disease are extracellular aggregation of amyloid β peptides and, the presence of intracellular neurofibrillary tangles formed by precipitation/aggregation of hyperphosphorylated tau protein. The etiology of Alzheimer's disease is multifactorial and a full understanding of its pathogenesis remains elusive. Some years ago, it has been suggested that glycation may contribute to both extensive protein cross-linking and oxidative stress in Alzheimer's disease. Glycation is an endogenous process that leads to the production of a class of compounds known as advanced glycation end products (AGEs). Interestingly, increased levels of AGEs have been observed in brains of Alzheimer's disease patients. Methylglyoxal, a reactive intermediate of cellular metabolism, is the most potent precursor of AGEs and is strictly correlated with an increase of oxidative stress in Alzheimer's disease. Many studies are showing that methylglyoxal and methylglyoxal-derived AGEs play a key role in the etiopathogenesis of Alzheimer's disease.

The probiotic Lactobacillus mucosae has been widely shown to have many positive effects. However, its neuroprotective effects and underlying mechanism in Alzheimer's disease (AD) remain elusive. Male APP/PS1 mice were treated for 4 weeks with L. mucosae WMU007, followed by the evaluation of cognitive function, neuronal damage, amyloid-β (Aβ) deposition, and Tau phosphorylation. RNA-seq coupled with Gene Ontology (GO) enrichment analysis implicated L. mucosae WMU007 in modulating oxidative stress in this AD model. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis and qPCR were performed to identify the specific mechanism by which this probiotic suppresses oxidative stress in the pathogenesis of AD. In addition, we quantified the levels of classical oxidative stress markers, such as superoxide dismutase 2 (SOD2) and glutathione peroxidase 4 (GPX4). We also examined the expression of cannabinoid receptor type 2 (CB2) and its key downstream regulators in the redox pathway, namely nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase 1 (HO-1), in both animal and cellular models. Our results showed that treatment with L. mucosae WMU007 significantly decreased cognitive impairment, neuronal damage, Aβ deposits, and Tau phosphorylation in APP/PS1 mice. Activation of CB2 was identified as the key mechanism by which L. mucosae WMU007 reduces oxidative stress in AD. In addition, L. mucosae WMU007 reduced oxidative stress and increased the levels of CB2 pathway-related proteins in vivo and in vitro. These results indicate that L. mucosae WMU007 confers neuroprotection in AD by targeting CB2-mediated oxidative pathways, highlighting its therapeutic potential as a novel probiotic intervention.

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by gradual and progressive cognitive decline leading to dementia. At its core, the neuropathological features of AD include hallmark accumulations of amyloid-β and hyperphosphorylated tau proteins. Other harmful processes, such as oxidative stress and inflammation, contribute to the disease's neuropathological progression. This review evaluates the role of oxidative stress in AD, placing a spotlight on the disappointing outcomes of various antioxidant clinical trials. Several hypotheses are discussed that might elucidate the failures of these therapies in AD. Specifically: 1) The paradoxical and overlooked harmful implications of prooxidant intermediates, particularly stemming from conventional antioxidants like vitamins E and C; 2) The challenges and failure to appreciate the issue of bioavailability-epitomized by the dictum "no on-site protection, no protection"-and the preeminent, yet often ignored, role played by endogenous antioxidant enzymes in combating oxidative stress; 3) The influence of unrecognized etiologies, such as latent infectious agents and others, as foundational drivers of oxidative stress in AD; 4) The underestimation of the complexity of oxidative mechanisms and the necessity of multi-targeted therapeutic approaches, such as those provided by various diets; and 5) The limitations of clinical trial designs in fully capturing the effects of antioxidants on AD progression. This article also examines the outcomes of select clinical trials while highlighting the challenges and barriers these therapies pose, offering insights into potential mechanisms to overcome their marginal success.

Introduction Alzheimer’s disease (AD) is the most common neurodegenerative disease across the world. The major cause of AD is extensive oxidative stress and inflammation in central nervous system (CNS). Vitamin D3 and E are the most known vitamins that control oxidative stress and mitochondrial respiratory function. They may prevent neuronal loss in AD. Few studies have been conducted to assess the effect of vitamins on AD. Therefore, the aim of this study was to assess the effect of vitamin D3 and E on AD. Methods: In this study, 60 rats were randomly divided into six groups (n = 10) namely the control group, sham group, AD group with intra-hippocampal Aβ1-40 injection, AD+vitamin D3 group, AD+vitamin E group and AD+vitamin D3 and E group. Memory and learning were measured by the Novel Object Recognition (NOR) test. Neuronal survival was assessed by H&E and cresyl violet staining, and oxidative stress was measured by malondialdehyde (MDA) level and superoxide dismutase (SOD) activity. In vitamin-treated groups, learning and memory, which were measured by NOR, improved significantly. Vitamin D3 and E administration decreased neuronal loss in AD brain rats. Results: Results showed that MDA decreased and SOD increased in treatment groups; but, a combination of vitamin D3 and E was more effective in decreasing oxidative stress in AD compared to other treatment groups. Conclusion: The present study indicated that vitamin D3 and E and their combination can improve memory and learning deficit, and decrease neuronal loss and oxidative stress in Alzheimer’s model.

Glutamate excitotoxicity and oxidative stress are held responsible for the pathogenesis of Alzheimer's disease (AD). Prolidase is known to have a crucial part in the recycling of proline for collagen synthesis. Elevated proline levels have been shown to increase glutamate concentration. To our knowledge, prolidase activity in AD has not yet been studied. In this study, we aimed to reveal the relationship of AD with oxidative stress and collagen turnover by comparing AD patients and healthy control group with regard to total antioxidant status (TAS), total oxidant status (TOS), and prolidase levels. Fifty patients (mean age, 72.5 ± 8.9 years) diagnosed with AD and a control group comprised of 39 healthy individuals (mean age, 69.1 ± 7.1 years) were compared relative to serum TAS, TOS, and prolidase levels. The relationship of cognitive performance with prolidase, TAS, and TOS was evaluated by Mini mental state examination (MMSE). Alzheimer's disease group demonstrated statistically significantly higher prolidase and TOS levels as compared to the control group (p = 0.01, p = 0.018, respectively). Total antioxidant status level was significantly lower in the dementia group than in the control group (p = 0.032). MMSE manifested a negative correlation with prolidase and TOS levels (p = 0.001, r = -0.33; p = 0.002, r = -0.32, respectively), while displaying a positive correlation with TAS levels (p = 0.002, r = 0.32). In conclusion, elevated prolidase and TOS levels along with reduced TAS concentrations suggest that oxidative stress and collagen breakdown are involved in the cognitive impairment in AD.

Increasing evidence demonstrates that oxidative stress causes damage to cell function with aging and is involved in a number of age-related disorders including atherosclerosis, arthritis, and neurodegenerative disorders. In the neurodegenerative diseases, oxidative stress has been implicated in amyotrophic lateral sclerosis, Parkinson disease, Huntington disease, and Alzheimer disease (AD). The neurodegenerative disorder receiving the most attention has been AD, in which an increase occurs in oxidation of brain lipids, carbohydrates, proteins, and DNA. Some of the products of oxidation have been found in the major histopathologic alterations in AD: the neurofibrillary tangles (NFTs) and senile plaques (reviewed in Markesbery and Carney 1 and Ceballos-Picot 2 ). These oxidative modifications are closely associated with a subtle inflammatory process in the brain in AD. Oxidative stress refers to a state in which free radicals and their products are in excess of antioxidant defense mechanisms. This imbalance can occur as a result of increased free radical production or a decrease in antioxidant defenses. Free radicals are defined as any atom or molecule that has one or more unpaired electrons in its outer shell. The reduction of molecular oxygen to water is a major source of potent radicals. The initial step in this reaction yields the superoxide radical, which produces hydrogen peroxide by addition of an electron. The reduction of hydrogen peroxide yields the highly reactive hydroxyl radical. These radicals plus singlet oxygen are called reactive oxygen species (ROS). Several reactive nitrogen species, nitric oxide, and peroxynitrite also are important modulators of oxidative stress. These free radicals and others are capable of reacting with lipids, proteins, nucleic acids, and other molecules and altering their structure and function. Oxidative stress can lead to alterations in cells with an accumulation of oxidized products such as aldehydes and isoprostanes from lipid peroxidation, protein carbonyls from protein oxidation, and base ad

It has now been established through multiple lines of evidence that oxidative stress is an early event in Alzheimer's disease, occurring prior to the canonical cytopathology. Thus, oxidative stress likely plays a key pathogenic role in the disease and is clearly involved in the cell loss and other neuropathology associated with Alzheimer's disease as demonstrated by the large number of metabolic signs of oxidative stress and by markers of oxidative damage. One puzzling observation, however, is that oxidative damage decreases with disease progression, such that levels of markers of rapidly formed oxidative damage, which are initially elevated, decrease as the disease progresses to advanced Alzheimer's disease. This finding indicates that reactive oxygen species not only cause damage to cellular structures but also provoke cellular responses, such as the compensatory upregulation of antioxidant enzymes found in vulnerable neurons in Alzheimer's disease. Not surprisingly, stress-activated protein kinase pathways, which are activated by oxidative stress, are extensively activated during Alzheimer's disease. In this review, we present the evidence of oxidative stress and compensatory responses that occur in Alzheimer's disease with a particular focus on the roles and mechanism of activation of stress-activated protein kinase pathways.

The temporal association between oxidative stress and the hallmark pathologies of Alzheimer disease (AD) demonstrates that oxidative stress is among the earliest events in the disease. Nonetheless, neither the consequences of oxidative stress nor how oxidative stress relates to other pathological features of the disease are clear at this point. To begin to address these issues, we investigated p38 kinase, which is induced by oxidative stress, in the pathogenesis of AD. In hippocampal and cortical brain regions of individuals with AD, p38 is exclusively localized in association with neurofibrillar pathology. By marked contrast, these brain regions exhibit a low level of diffuse p38 staining in the neuronal cytoplasm in controls. We found a complete overlap of the immunostaining profiles of p38 and tau-positive neurofibrillary pathology and that the majority of p38 was activated in AD neurons, both of which support an association of p38 with the disease process. Moreover, the finding that PHF-tau co-immunoprecipitates with p38, and that p38 co-purifies with PHF-tau, strongly suggests that they are physically associated in vivo. Since p38 is also implicated in cell cycle regulation, our findings provide a link between the cell cycle re-entrant phenotype, cytoskeletal phosphorylation and oxidative stress in AD.

Tau Pathology Generated by Overexpression of Tau