Markers of oxidative damage to lipids, nucleic acids and proteins and antioxidant enzymes activities in Alzheimer's disease brain: A meta-analysis in human pathological specimens

The Vital Role of Melatonin and Its Metabolites in the Neuroprotection and Retardation of Brain Aging

While primarily produced in the pineal gland, melatonin's influence goes beyond its well-known role in regulating sleep, nighttime metabolism, and circadian rhythms, in the field of chronobiology. A plethora of new data demonstrates melatonin to be a very powerful molecule, being a potent ROS/RNS scavenger with anti-inflammatory, immunoregulatory, and oncostatic properties. Melatonin and its metabolites exert multiple beneficial effects in cutaneous and systemic aging. This review is focused on the neuroprotective role of melatonin during aging. Melatonin has an anti-aging capacity, retarding the rate of healthy brain aging and the development of age-related neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, multiple sclerosis, amyotrophic lateral sclerosis, etc. Melatonin, as well as its metabolites, N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK) and N1-acetyl-5-methoxykynuramine (AMK), can reduce oxidative brain damage by shielding mitochondria from dysfunction during the aging process. Melatonin could also be implicated in the treatment of neurodegenerative conditions, by modifying their characteristic low-grade neuroinflammation. It can either prevent the initiation of inflammatory responses or attenuate the ongoing inflammation. Drawing on the current knowledge, this review discusses the potential benefits of melatonin supplementation in preventing and managing cognitive impairment and neurodegenerative diseases.

Therapeutic potential of Thai herbal formula for cognitive impairment: A metabolomics approach for Comprehensive Insights

Chronic cerebral ischemia hypoperfusion plays a role in the initiation and progression of vascular dementia, which causes changes in metabolites. Currently, there is no standard treatment to treat, prevent and reduce the severity of this condition. Thai herbal Yahom no.20 (YHF20) is indicated for fatigue and dizziness. The components of YHF20 have been found to have pharmacological effects related to the pathology of chronic cerebral ischemia hypoperfusion. This study aimed to investigate metabolomic changes after YHF20 administration in a rat model of permanent bilateral common carotid artery occlusion (2-VO) induced chronic cerebral ischemia hypoperfusion, and to explore its impact on spatial learning and memory. Albino Wistar rats were randomly allocated to 5 groups; sham, 2-VO, 2-VO+ 100 mg/kg YHF20, 2-VO+300 mg/kg YHF20, and 2-VO+1000 mg/kg YHF20. The rats were administered YHF20 daily by oral gavage for 56 days after 2-VO induction. Plasma was collected weekly for metabolome change analysis using LC-MS/QTof and toxicity study. The rats were evaluated for spatial learning and memory using the Morris water maze. The results showed that 78 known metabolites and 10 tentative pathways altered after chronic cerebral hypoperfusion, although it was not able to determine the effect on memory and learning behaviors of rats. Glutathione and glutathione metabolism might be metabolite-pathway that were the affect after YHF20 administration in cerebral ischemic condition. The 4 known metabolites may be the metabolites from the constituents of YHF20 could be considered and confirmed for quality control purpose. In conclusion, YHF20 administration might contribute to metabolic changes related to cerebral ischemia condition without the effect on spatial learning and memory, including hepatotoxicity and nephrotoxicity after 56 days of treatment. Alterations in the potential metabolites may provide data support for elucidating dementia pathogenesis and selecting pathways for intervention.

Redox imbalance and metabolic defects in the context of Alzheimer disease

Redox reactions play a critical role for intracellular processes, including pathways involved in metabolism and signaling. Reactive oxygen species (ROS) act either as second messengers or generators of protein modifications, fundamental mechanisms for signal transduction. Disturbance of redox homeostasis is associated with many disorders. Among these, Alzheimer's disease is a neurodegenerative pathology that presents hallmarks of oxidative damage such as increased ROS production, decreased activity of antioxidant enzymes, oxidative modifications of macromolecules, and changes in mitochondrial homeostasis. Interestingly, alteration of redox homeostasis is closely associated with defects of energy metabolism, involving both carbohydrates and lipids, the major energy fuels for the cell. As the brain relies exclusively on glucose metabolism, defects of glucose utilization represent a harmful event for the brain. During aging, a progressive perturbation of energy metabolism occurs resulting in brain hypometabolism. This condition contributes to increase neuronal cell vulnerability ultimately resulting in cognitive impairment. The current review discusses the crosstalk between alteration of redox homeostasis and brain energy defects that seems to act in concert in promoting Alzheimer's neurodegeneration.

Respiratory Dysfunction in Alzheimer's Disease-Consequence or Underlying Cause? Applying Animal Models to the Study of Respiratory Malfunctions

Alzheimer's disease (AD) is a neurodegenerative brain disease that is the most common cause of dementia among the elderly. In addition to dementia, which is the loss of cognitive function, including thinking, remembering, and reasoning, and behavioral abilities, AD patients also experience respiratory disturbances. The most common respiratory problems observed in AD patients are pneumonia, shortness of breath, respiratory muscle weakness, and obstructive sleep apnea (OSA). The latter is considered an outcome of Alzheimer's disease and is suggested to be a causative factor. While this narrative review addresses the bidirectional relationship between obstructive sleep apnea and Alzheimer's disease and reports on existing studies describing the most common respiratory disorders found in patients with Alzheimer's disease, its main purpose is to review all currently available studies using animal models of Alzheimer's disease to study respiratory impairments. These studies on animal models of AD are few in number but are crucial for establishing mechanisms, causation, implementing potential therapies for respiratory disorders, and ultimately applying these findings to clinical practice. This review summarizes what is already known in the context of research on respiratory disorders in animal models, while pointing out directions for future research.

Cerebrospinal fluid neutral lipids predict progression from mild cognitive impairment to Alzheimer's disease

Genetic, metabolic, and clinical evidence links lipid dysregulation to an increased risk of Alzheimer's disease (AD). However, the role of lipids in the pathophysiological processes of AD and its clinical progression is unclear. We investigated the association between cerebrospinal fluid (CSF) lipidome and the pathological hallmarks of AD, progression from mild cognitive impairment (MCI) to AD, and the rate of cognitive decline in MCI patients. The CSF lipidome was analyzed by liquid chromatography coupled to mass spectrometry in an LC-ESI-QTOF-MS/MS platform for 209 participants: 91 AD, 92 MCI, and 26 control participants. The MCI patients were followed up for a median of 58 (± 12.5) months to evaluate their clinical progression to AD. Forty-eight (52.2%) MCI patients progressed to AD during follow-up. We found that higher CSF levels of hexacosanoic acid and ceramide Cer(d38:4) were associated with an increased risk of amyloid beta 42 (Aβ42) positivity in CSF, while levels of phosphatidylethanolamine PE(40:0) were associated with a reduced risk. Higher CSF levels of sphingomyelin SM(30:1) were positively associated with pathological levels of phosphorylated tau in CSF. Cholesteryl ester CE(11D3:1) and an unknown lipid were recognized as the most associated lipid species with MCI to AD progression. Furthermore, TG(O-52:2) was identified as the lipid most strongly associated with the rate of progression. Our results indicate the involvement of membrane and intracellular neutral lipids in the pathophysiological processes of AD and the progression from MCI to AD dementia. Therefore, CSF neutral lipids can be used as potential prognostic markers for AD.

Oxidative damage in neurodegeneration: roles in the pathogenesis and progression of Alzheimer disease

Alzheimer disease (AD) is associated with multiple etiologies and pathological mechanisms, among which oxidative stress (OS) appears as a major determinant. Intriguingly, OS arises in various pathways regulating brain functions, and it seems to link different hypotheses and mechanisms of AD neuropathology with high fidelity. The brain is particularly vulnerable to oxidative damage, mainly because of its unique lipid composition, resulting in an amplified cascade of redox reactions that target several cellular components/functions ultimately leading to neurodegeneration. The present review highlights the "OS hypothesis of AD," including amyloid beta-peptide-associated mechanisms, the role of lipid and protein oxidation unraveled by redox proteomics, and the antioxidant strategies that have been investigated to modulate the progression of AD. Collected studies from our groups and others have contributed to unraveling the close relationships between perturbation of redox homeostasis in the brain and AD neuropathology by elucidating redox-regulated events potentially involved in both the pathogenesis and progression of AD. However, the complexity of AD pathological mechanisms requires an in-depth understanding of several major intracellular pathways affecting redox homeostasis and relevant for brain functions. This understanding is crucial to developing pharmacological strategies targeting OS-mediated toxicity that may potentially contribute to slow AD progression as well as improve the quality of life of persons with this severe dementing disorder.

Superoxide Dismutase Modified the Association of Serum Malondialdehyde Levels with Cognitive Decline Among Older Adults: Findings from the Chinese Longitudinal Healthy Longevity Survey

Background

Numerous studies have investigated the correlation between malondialdehyde (MDA) and cognitive decline. However, limited research has explored the interplay between superoxide dismutase (SOD), C-reactive protein (CRP), and MDA.

Objective

This study aims to scrutinize the association between MDA and cognitive function in older adults, while also elucidating the roles of SOD and CRP within this relationship.

Methods

Utilizing data from the Chinese Longitudinal Healthy Longevity Survey (CLHLS) spanning 2008-2009, 2011-2012, and 2014, this study included 2,696 eligible subjects. Cognitive function was evaluated using the Chinese version of the Mini-Mental State Examination (MMSE). Linear mixed-effects models were employed to examine the links between MDA, SOD, CRP, and their interactions with cognitive function.

Results

Elevated serum levels of MDA and CRP, as well as decreased serum SOD levels, were related to decreased cognitive function (β= -0.220 and -0.346, 95% CI: -0.399, -0.041 and -0.526, -0.167 for MDA and CRP; β= 0.384, 95% CI: 0.204, 0.564 for SOD). Notably, a significant interaction between MDA and SOD was detected (p = 0.001). An increase per standard deviation in serum MDA levels was significantly associated with a 0.347-point lower MMSE score only in participants with normal cognitive function and high SOD levels (β= -0.347, 95% CI: -0.497, -0.197; p < 0.001).

Conclusions

Elevated serum MDA levels in the normal population with high SOD levels suggested diminished cognitive performance. Combining MDA with SOD could be pivotal in identifying older adults at risk of cognitive decline in clinical settings.

Selenium and zinc protect against heavy metal mixture-induced, olfactory bulb and hippocampal damage by augmenting antioxidant capacity and activation of Nrf2-Hmox-1 signaling in male rats

PURPOSE/AIM OF THE STUDY

Heavy metals and metalloids have been implicated in neurodenerative diseases. Present study has evaluated the potential protective effects of Se and Zn on heavy metals and metalloids mixture-induced (Cd, Pb, Hg and As) toxicity in the hippocampus and olfactory bulb in male rats.

MATERIALS AND METHODS

Five groups of Wistar rats were randomly divided in to: controls, toxic metals mixture (TMM) exposed rats (PbCl2, 20 mg·kg-1; CdCl2, 1.61 mg·kg-1; HgCl2, 0.40 mg·kg-1 and NaAsO3, 10 mg·kg-1)), TMM + Zn, TMM + Se and TMM-+Zn + Se groups and were orally treated for 60 days.

RESULTS

We found that in hippocampus and olfactory bulb, TMM generated increased lipid peroxidation and diminished antioxidant capacity. These adverse effects induced by TMM were alleviated by Zn and Se co-treatment; moreover, essential trace elements (Zn and Se) decreased activity of acetylcholinesterase, reduced Cd, Pb, Hg and As bioaccumulation in hippocampus and olfactory bulb and decreased levels of TNF-α in the hippocampus. TMM treated rats had lower levels of Hmox-1 (hippocampus), higher levels of Nrf2 (olfactory bulb and hippocampus) and NF-kB (olfactory bulb). TMM treated rats showed significantly highest time in locating the escape hole. Histopathological examination revealed hypertrophied granule cells in OB of TMM exposed rats.

CONCLUSION

Zn and Se supplementation can reverse quaternary mixture-induced (Cd, Pb, Hg and As) toxicity in hippocampus and OB in male albino rats.

Ameliorative effects of pine nut peptide-zinc chelate (Korean pine) on a mouse model of Alzheimer's disease

In this study, 50 SD adult male mice were used to create an Alzheimer's disease model. The mice's learning and memory abilities were evaluated using an eight-arm radial maze experiment, and changes in body weight and food intake were noted. This helped to better validate the improvement of Alzheimer's disease caused by pine nut peptide-zinc chelate (Korean pine). For a more thorough investigation, mice's brains were dissected, Endogenous mercaptan antioxidants (enzymes), which are markers of brain tissue, were assessed, and mouse gut flora was analyzed. The findings demonstrated that pine nut peptide-zinc chelate (Korean pine) can improve learning and memory, stop brain aging and damage, and control gut flora in mice. It may exert its effects by ameliorating decreased AChE levels and increased ChAT levels in the central cholinergic system, endogenous thiol antioxidants (enzymes) in the cerebral cortex, and by controlling the bacterial flora in the gut.

Lipidomic Alterations in the Cerebral Cortex and White Matter in Sporadic Alzheimer's Disease

Non-targeted LC-MS/MS-based lipidomic analysis was conducted in post-mortem human grey matter frontal cortex area 8 (GM) and white matter of the frontal lobe centrum semi-ovale (WM) to identify lipidome fingerprints in middle-aged individuals with no neurofibrillary tangles and senile plaques, and cases at progressive stages of sporadic Alzheimer's disease (sAD). Complementary data were obtained using RT-qPCR and immunohistochemistry. The results showed that WM presents an adaptive lipid phenotype resistant to lipid peroxidation, characterized by a lower fatty acid unsaturation, peroxidizability index, and higher ether lipid content than the GM. Changes in the lipidomic profile are more marked in the WM than in GM in AD with disease progression. Four functional categories are associated with the different lipid classes affected in sAD: membrane structural composition, bioenergetics, antioxidant protection, and bioactive lipids, with deleterious consequences affecting both neurons and glial cells favoring disease progression.

Changes in Plasma Neutral and Ether-Linked Lipids Are Associated with The Pathology and Progression of Alzheimer's Disease

Aberrant lipid metabolism has been strongly linked to Alzheimer's disease (AD) pathogenesis. However, the role of lipids in the pathophysiological processes of AD and their clinical progression is unclear. We hypothesized that plasma lipids are associated with the pathological hallmarks of AD, progression from mild cognitive impairment (MCI) to AD, and the rate of cognitive decline in MCI patients. To evaluate our hypotheses, we analysed the plasma lipidome profile by liquid chromatography coupled to mass spectrometry in an LC-ESI-QTOF-MS/MS platform for 213 subjects recruited consecutively: 104 AD, 89 MCI, and 20 control subjects. Forty-seven (52.8%) MCI patients progressed to AD during follow-up (58 ± 12.5 months). We found that higher plasma levels of sphingomyelin SM(36:0) and diglyceride DG(44:3) were associated with an increased risk of amyloid beta 42 (Aβ42) positivity in CSF, while levels of SM(40:1) were associated with a reduced risk. Higher plasma levels of ether-linked triglyceride TG(O-60:10) were negatively associated with pathological levels of phosphorylated tau in CSF. Plasma levels of fatty acid ester of hydroxy fatty acid FAHFA(34:0) and ether-linked phosphatidylcholine PC(O-36:1) were positively associated with pathological levels of total tau in CSF. Regarding the plasma lipids most associated with progression from MCI to AD, our analysis detected phosphatidyl-ethanolamine plasmalogen PE(P-36:4), TG(59:12), TG(46:0), and TG(O-62:7). Furthermore, TG(O-62:7) was the lipid that was most strongly associated with the rate of progression. In conclusion, our results indicate that neutral and ether-linked lipids are involved in the pathophysiological processes of AD and the progression from MCI to AD dementia, suggesting the involvement of lipid-mediated antioxidant mechanisms in AD.

Deciphering the Mysterious Relationship between the Cross-Pathogenetic Mechanisms of Neurodegenerative and Oncological Diseases

The relationship between oncological pathologies and neurodegenerative disorders is extremely complex and is a topic of concern among a growing number of researchers around the world. In recent years, convincing scientific evidence has accumulated that indicates the contribution of a number of etiological factors and pathophysiological processes to the pathogenesis of these two fundamentally different diseases, thus demonstrating an intriguing relationship between oncology and neurodegeneration. In this review, we establish the general links between three intersecting aspects of oncological pathologies and neurodegenerative disorders, i.e., oxidative stress, epigenetic dysregulation, and metabolic dysfunction, examining each process in detail to establish an unusual epidemiological relationship. We also focus on reviewing the current trends in the research and the clinical application of the most promising chemical structures and therapeutic platforms that have a modulating effect on the above processes. Thus, our comprehensive analysis of the set of molecular determinants that have obvious cross-functional pathways in the pathogenesis of oncological and neurodegenerative diseases can help in the creation of advanced diagnostic tools and in the development of innovative pharmacological strategies.

Effect of donepezil hydrochloride on the transgenic Drosophila expressing human Aβ-42

CONCLUSION

The results suggest that donepezil hydrochloride is potent enough to reduce the AD symptoms being mimicked in transgenic flies.

Involvement of antioxidant enzymes in Parkinson's disease

Similar to many other diseases, the etiology of Parkinson's disease (PD) is multifactorial and includes both genetic and environmental factors. Exposure to pesticides and the production of reactive oxygen species (ROS) in the body, mainly in electron transporter complexes 1 and 2 in the inner mitochondrial membrane, are two primary environmental risk factors for this disease. Increased accumulation of ROS and oxidative stress (OS) trigger a series of reactions that can lead to the aggregation of misfolded proteins, DNA damage, autophagy, and apoptosis, which may adversely affect cell function. These processes cause diseases such as coronary artery disease (CAD), Alzheimer's disease (AD), and PD. As indicated in previous studies, ROS is considered a critical regulator in the progression of PD. The human body contains several antioxidant molecules, such as vitamin A, vitamin C, bilirubin, and uric acid, as well as antioxidant enzymes including paraoxonase (PON), glutathione reductase (GR), glutathione peroxidase (GPx), catalase (CAT), and superoxide dismutase (SOD). Therefore, based on the canonical function of the antioxidant enzymes in PD, In the present review, we attempted to examine the function of antioxidant enzymes in PD.

Cerebrospinal fluid lipidomic fingerprint of obstructive sleep apnoea in Alzheimer's disease

BACKGROUND

Obstructive sleep apnoea (OSA) has a high prevalence in patients with Alzheimer's disease (AD). Both conditions have been shown to be associated with lipid dysregulation. However, the relationship between OSA severity and alterations in lipid metabolism in the brains of patients with AD has yet to be fully elucidated. In this context, we examined the cerebrospinal fluid (CSF) lipidome of patients with suspected OSA to identify potential diagnostic biomarkers and to provide insights into the pathophysiological mechanisms underlying the effect of OSA on AD.

METHODS

The study included 91 consecutive AD patients who underwent overnight polysomnography (PSG) to diagnose severe OSA (apnoea-hypopnea index ≥ 30/h). The next morning, CSF samples were collected and analysed by liquid chromatography coupled to mass spectrometry in an LC-ESI-QTOF-MS/MS platform.

RESULTS

The CSF levels of 11 lipid species were significantly different between AD patients with (N = 38) and without (N = 58) severe OSA. Five lipids (including oxidized triglyceride OxTG(57:2) and four unknown lipids) were significantly correlated with specific PSG measures of OSA severity related to sleep fragmentation and hypoxemia. Our analyses revealed a 4-lipid signature (including oxidized ceramide OxCer(40:6) and three unknown lipids) that provided an accuracy of 0.80 (95% CI: 0.71-0.89) in the detection of severe OSA. These lipids increased the discriminative power of the STOP-Bang questionnaire in terms of the area under the curve (AUC) from 0.61 (0.50-0.74) to 0.85 (0.71-0.93).

CONCLUSIONS

Our results reveal a CSF lipidomic fingerprint that allows the identification of AD patients with severe OSA. Our findings suggest that an increase in central nervous system lipoxidation may be the principal mechanism underlying the association between OSA and AD.

Association between insulin and Nrf2 signalling pathway in Alzheimer's disease: A molecular landscape

Insulin, a well-known hormone, has been implicated as a regulator of blood glucose levels for almost a century now. Over the past few decades, the non-glycemic actions of insulin i.e. neuronal growth and proliferation have been extensively studied. In 2005, Dr. Suzanne de La Monte and her team reported that insulin might be involved in the pathogenesis of Alzheimer's Disease (AD) and thus coined a term "Type-3 diabetes" This hypothesis was supported by several subsequent studies. The nuclear factor erythroid 2- related factor 2 (Nrf2) triggers a cascade of events under the regulation of distinct mechanisms including protein stability, phosphorylation and nuclear cytoplasmic shuttling, finally leading to the protection against oxidative damage. The Nrf2 pathway has been investigated extensively in relevance to neurodegenerative disorders, particularly AD. Many studies have indicated a strong correlation between insulin and Nrf2 signalling pathways both in the periphery and the brainbut merely few of them have focused on elucidating their inter-connective role in AD. The present review emphasizes key molecular pathways that correlate the role of insulin with Nrf2 during AD. The review has also identified key unexplored areas that could be investigated in future to further establish the insulin and Nrf2 influence in AD.

Differential relationships of NMDAR hypofunction and oxidative stress with cognitive decline

NMDAR hypofunction and oxidative stress are implicated in the pathogenesis of Alzheimer's disease. D-amino acid oxidase (DAO) regulates NMDAR function. Glutathione, superoxide dismutase, and catalase are three first-line endogenous antioxidants. This study explored the associations of these potential biomarkers with mild cognitive impairment. Cognitive function and blood levels of DAO, glutathione, superoxide dismutase, and catalase were measured in 63 mild cognitive impairment patients and 24 healthy individuals every 6 months for 2 years. Among the patients, DAO and glutathione levels at baseline contributed to the cognitive decline 2 years later. Among the healthy individuals, only glutathione levels were associated with cognitive change. The four biomarkers differed in change directions (upward vs. downward) in the patients and in the healthy individuals. Among patients, glutathione levels were negatively correlated with superoxide dismutase and positively correlated with catalase, and DAO levels were negatively correlated with superoxide dismutase. To our knowledge, this is the first study to demonstrate the differential associations of NMDAR hypofunction and oxidative stress with cognitive change between the mild cognitive impairment patients and healthy people. Glutathione may be regarded as an aging marker for both mild cognitive impairment and normal aging; and DAO, a biomarker exclusively for mild cognitive impairment.

Plasma and cerebrospinal fluid nonenzymatic protein damage is sustained in Alzheimer's disease

BACKGROUND

Oxidative stress is considered to play an important role in the pathogenesis of Alzheimer's disease (AD). It has been observed that oxidative damage to specific protein targets affecting particular functional networks is one of the mechanisms by which oxidative stress contributes to neuronal failure and consequently loss of cognition and AD progression. Studies are lacking in which oxidative damage is measured at both systemic and central fluid levels and in the same cohort of patients. We aimed to determine the levels of both plasma and cerebrospinal fluid (CSF) nonenzymatic protein damage in patients in the continuum of AD and to evaluate the relation of this damage with clinical progression from mild cognitive impairment (MCI) to AD.

METHODS

Different markers of nonenzymatic post-translational protein modification, mostly from oxidative processes, were detected and quantified in plasma and CSF by isotope dilution gas chromatography‒mass spectrometry using selected ion monitoring (SIM-GC/MS) for 289 subjects: 103 AD, 92 MCI, and 94 control subjects. Characteristics of the study population such as age, sex, Mini-mental state examination, CSF AD biomarkers, and APOE ϵ4, were also considered.

RESULTS

Forty-seven (52.8%) MCI patients progressed to AD during follow-up (58 ± 12.5 months). After controlling for age, sex, and APOE ϵ4 allele, plasma and CSF concentrations of protein damage markers were not associated with either diagnosis of AD or MCI. The CSF levels of nonenzymatic protein damage markers were associated with none of the CSF AD biomarkers. In addition, neither in CSF nor in plasma were the levels of protein damage associated with the MCI to AD progression.

CONCLUSION

The lack of association between both CSF and plasma concentrations of nonenzymatic protein damage markers and AD diagnosis and progression suggests that oxidative damage in AD is a pathogenic mechanism specifically expressed at the cell-tissue level, not in extracellular fluids.

Protective Roles of Hydrogen Sulfide in Alzheimer's Disease and Traumatic Brain Injury

The gaseous signaling molecule hydrogen sulfide (H₂S) critically modulates a plethora of physiological processes across evolutionary boundaries. These include responses to stress and other neuromodulatory effects that are typically dysregulated in aging, disease, and injury. H₂S has a particularly prominent role in modulating neuronal health and survival under both normal and pathologic conditions. Although toxic and even fatal at very high concentrations, emerging evidence has also revealed a pronounced neuroprotective role for lower doses of endogenously generated or exogenously administered H₂S. Unlike traditional neurotransmitters, H₂S is a gas and, therefore, is unable to be stored in vesicles for targeted delivery. Instead, it exerts its physiologic effects through the persulfidation/sulfhydration of target proteins on reactive cysteine residues. Here, we review the latest discoveries on the neuroprotective roles of H₂S in Alzheimer's disease (AD) and traumatic brain injury, which is one the greatest risk factors for AD.

Inflammatory Processes in Alzheimer's Disease-Pathomechanism, Diagnosis and Treatment: A Review

Alzheimer's disease is one of the most commonly diagnosed cases of senile dementia in the world. It is an incurable process, most often leading to death. This disease is multifactorial, and one factor of this is inflammation. Numerous mediators secreted by inflammatory cells can cause neuronal degeneration. Neuritis may coexist with other mechanisms of Alzheimer's disease, contributing to disease progression, and may also directly underlie AD. Although much has been established about the inflammatory processes in the pathogenesis of AD, many aspects remain unexplained. The work is devoted in particular to the pathomechanism of inflammation and its role in diagnosis and treatment. An in-depth and detailed understanding of the pathomechanism of neuroinflammation in Alzheimer's disease may help in the development of diagnostic methods for early diagnosis and may contribute to the development of new therapeutic strategies for the disease.

Could Alzheimer's disease be a maladaptation of an evolutionary survival pathway mediated by intracerebral fructose and uric acid metabolism?

An important aspect of survival is to assure enough food, water, and oxygen. Here, we describe a recently discovered response that favors survival in times of scarcity, and it is initiated by either ingestion or production of fructose. Unlike glucose, which is a source for immediate energy needs, fructose metabolism results in an orchestrated response to encourage food and water intake, reduce resting metabolism, stimulate fat and glycogen accumulation, and induce insulin resistance as a means to reduce metabolism and preserve glucose supply for the brain. How this survival mechanism affects brain metabolism, which in a resting human amounts to 20% of the overall energy demand, is only beginning to be understood. Here, we review and extend a previous hypothesis that this survival mechanism has a major role in the development of Alzheimer's disease and may account for many of the early features, including cerebral glucose hypometabolism, mitochondrial dysfunction, and neuroinflammation. We propose that the pathway can be engaged in multiple ways, including diets high in sugar, high glycemic carbohydrates, and salt. In summary, we propose that Alzheimer's disease may be the consequence of a maladaptation to an evolutionary-based survival pathway and what had served to enhance survival acutely becomes injurious when engaged for extensive periods. Although more studies are needed on the role of fructose metabolism and its metabolite, uric acid, in Alzheimer's disease, we suggest that both dietary and pharmacologic trials to reduce fructose exposure or block fructose metabolism should be performed to determine whether there is potential benefit in the prevention, management, or treatment of this disease.

The Rat Brain Transcriptome: From Infancy to Aging and Sporadic Alzheimer's Disease-like Pathology

It has been suggested that functional traits of the adult brain-all of which are established early in life-may affect the brain's susceptibility to Alzheimer's disease (AD). Results of our previous studies on senescence-accelerated OXYS rats, a model of sporadic AD, support this hypothesis. Here, to elucidate the molecular genetic nature of the aberrations revealed during brain maturation, we analyzed transcriptomes (RNA-seq data) of the prefrontal cortex (PFC) and hippocampus of OXYS rats and Wistar (control) rats in the period of brain maturation critical for OXYS rats (ages P3 and P10; P: postnatal day). We found more than 1000 differentially expressed genes in both brain structures; functional analysis indicated reduced efficiency of the formation of neuronal contacts, presumably explained mainly by deficits of mitochondrial functions. Next, we compared differentially expressed genes in the rat PFC and hippocampus from infancy to the progressive stage of AD-like pathology (five ages in total). Three genes (Thoc3, Exosc8, and Smpd4) showed overexpression in both brain regions of OXYS rats throughout the lifespan. Thus, reduced efficiency of the formation of neural networks in the brain of OXYS rats in infancy likely contributes to the development of their AD-like pathology.

Blood-based lipidomic signature of severe obstructive sleep apnoea in Alzheimer's disease

Background

Obstructive sleep apnoea (OSA) is the most frequent form of sleep-disordered breathing in patients with Alzheimer’s disease (AD). Available evidence demonstrates that both conditions are independently associated with alterations in lipid metabolism. However, it is unknown whether the expression of lipids is different between AD patients with and without severe OSA. In this context, we examined the plasma lipidome of patients with suspected OSA, aiming to identify potential diagnostic biomarkers and to provide insights into the pathophysiological mechanisms underlying the disease.

Methods

The study included 103 consecutive patients from the memory unit of our institution with a diagnosis of AD. The individuals were subjected to overnight polysomnography (PSG) to diagnose severe OSA (apnoea-hypopnea index ≥30/h), and blood was collected the following morning. Untargeted plasma lipidomic profiling was performed using liquid chromatography coupled with mass spectrometry.

Results

We identified a subset of 44 lipids (mainly phospholipids and glycerolipids) that were expressed differently between patients with AD and severe and nonsevere OSA. Among the lipids in this profile, 30 were significantly correlated with specific PSG measures of OSA severity related to sleep fragmentation and hypoxemia. Machine learning analyses revealed a 4-lipid signature (phosphatidylcholine PC(35:4), cis-8,11,14,17-eicosatetraenoic acid and two oxidized triglycerides (OxTG(58:5) and OxTG(62:12)) that provided an accuracy (95% CI) of 0.78 (0.69–0.86) in the detection of OSA. These same lipids improved the predictive power of the STOP-Bang questionnaire in terms of the area under the curve (AUC) from 0.61 (0.50–0.74) to 0.80 (0.70–0.90).

Conclusion

Our results show a plasma lipidomic fingerprint that allows the identification of patients with AD and severe OSA, allowing the personalized management of these individuals. The findings suggest that oxidative stress and inflammation are potential prominent mechanisms underlying the association between OSA and AD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13195-022-01102-8.

Targeting the liver in dementia and cognitive impairment: Dietary macronutrients and diabetic therapeutics

Many people living with dementia and cognitive impairment have dysfunctional mitochondrial and insulin-glucose metabolism resembling type 2 diabetes mellitus and old age. Evidence from human trials shows that nutritional interventions and anti-diabetic medicines that target nutrient-sensing pathways overcome these deficits in glucose and energy metabolism and can improve cognition and/or reduce symptoms of dementia. The liver is the main organ that mediates the systemic effects of diets and many diabetic medicines; therefore, it is an intermediate target for such dementia interventions. A challenge is the efficacy of these treatments in older age. Solutions include the targeted hepatic delivery of diabetic medicines using nanotechnologies and titration of macronutrients to optimize hepatic energy metabolism.

Reduced Hippocampal and Anterior Cingulate Expression of Antioxidant Enzymes and Membrane Progesterone Receptors in Alzheimer's Disease with Depression

BACKGROUND

Major depressive disorder (MDD) is a risk factor for dementia including that caused by Alzheimer's disease (AD). Both MDD and AD have a higher prevalence in women than men, and estrogen-related processes have been implicated in this sex difference.

OBJECTIVE

To identify if enhanced oxidative stress and decreased expression of the memory enhancer insulin-like growth factor 2 (IGF2), each implicated separately in MDD and AD, are exaggerated in individuals with both AD and MDD compared to those with AD.

METHODS

Expression of target genes are determined by qPCR in postmortem hippocampus (Hip) and anterior cingulate cortex (ACC) of individuals with dementia and autopsy confirmed AD and those of AD+MDD.

RESULTS

Transcript levels of the antioxidant enzymes catalase (CAT) and superoxide dismutase 1 (SOD1), as well as IGF2 and its receptor (IGF2R) were significantly lower in the Hip and ACC of individuals with both AD and MDD compared to those with AD and no MDD. Expressions of Progestin and AdipoQ Receptor Family Member 7 (PAQR7, alias progesterone receptor alpha, mPRa) and PAQR8 (mPRβ), receptors that bind neurosteroids, were also lower in the Hip and ACC of AD+MDD samples compared to those of AD without MDD. Correlations among these transcripts revealed that estrogen receptor 2 (ESR2) and mPR β are direct or indirect regulators of the expression of the antioxidant enzymes and IGF2R.

CONCLUSION

Reduced levels of antioxidant enzymes, decreased IGF2 expression, and diminished estrogen or membrane progesterone receptor-dependent processes might be more pronounced in the subpopulation of individuals with AD and MDD than without MDD.

Antarctic Marine Algae Extracts as a Potential Natural Resource to Protect Epithelial Barrier Integrity

The intestine and skin provide crucial protection against the external environment. Strengthening the epithelial barrier function of these organs is critical for maintaining homeostasis against inflammatory stimuli. Recent studies suggest that polar marine algae are a promising bioactive resource because of their adaptation to extreme environments. To investigate the bioactive properties of polar marine algae on epithelial cells of the intestine and skin, we created extracts of the Antarctic macroalgae Himantothallus grandifolius, Plocamium cartilagineum, Phaeurus antarcticus, and Kallymenia antarctica, analyzed the compound profiles of the extracts using gas chromatography-mass spectrometry, and tested the protective activities of the extracts on human intestinal and keratinocyte cell lines by measuring cell viability and reactive oxygen species scavenging. In addition, we assessed immune responses modulated by the extracts by real-time polymerase chain reaction, and we monitored the barrier-protective activities of the extracts on intestinal and keratinocyte cell lines by measuring transepithelial electrical resistance and fluorescence-labeled dextran flux, respectively. We identified bioactive compounds, including several fatty acids and lipid compounds, in the extracts, and found that the extracts perform antioxidant activities that remove intracellular reactive oxygen species and scavenge specific radicals. Furthermore, the Antarctic marine algae extracts increased cell viability, protected cells against inflammatory stimulation, and increased the barrier integrity of cells damaged by lipopolysaccharide or ultraviolet radiation. These results suggest that Antarctic marine algae have optimized their composition for polar environments, and furthermore, that the bioactive properties of compounds produced by Antarctic marine algae can potentially be used to develop therapeutics to promote the protective barrier function of the intestine and skin.

Optimization of a Method for Detecting Intracellular Sulfane Sulfur Levels and Evaluation of Reagents That Affect the Levels in Escherichia coli

Sulfane sulfur is a class of compounds containing zero-valent sulfur. Most sulfane sulfur compounds are reactive and play important signaling roles. Key enzymes involved in the production and metabolism of sulfane sulfur have been characterized; however, little is known about how to change intracellular sulfane sulfur (iSS) levels. To accurately measure iSS, we optimized a previously reported method, in which reactive iSS reacts with sulfite to produce thiosulfate, a stable sulfane sulfur compound, before detection. With the improved method, several factors were tested to influence iSS in Escherichia coli. Temperature, pH, and osmotic pressure showed little effect. At commonly used concentrations, most tested oxidants, including hydrogen peroxide, tert-butyl hydroperoxide, hypochlorous acid, and diamide, did not affect iSS, but carbonyl cyanide m-chlorophenyl hydrazone increased iSS. For reductants, 10 mM dithiothreitol significantly decreased iSS, but tris(2-carboxyethyl)phosphine did not. Among different sulfur-bearing compounds, NaHS, cysteine, S₂O₃²⁻ and diallyl disulfide increased iSS, of which only S₂O₃²⁻ did not inhibit E. coli growth at 10 mM or less. Thus, with the improved method, we have identified reagents that may be used to change iSS in E. coli and other organisms, providing tools to further study the physiological functions of iSS.

Hydroalcoholic Leaf Extract of Isatis tinctoria L. via Antioxidative and Anti-Inflammatory Effects Reduces Stress-Induced Behavioral and Cellular Disorders in Mice

Stress that can occur at different levels of a person’s life can cause and exacerbate various diseases. Oxidative stress and inflammation underlie this process at the cellular level. There is an urgent need to identify new and more effective therapeutic targets for the treatment of stress-induced behavioral disorders and specific drugs that affect these targets. Isatis tinctoria L. is a herbaceous species in the Brassicaceae family. Due to its potential antioxidant, nitric oxide- (NO-) inhibiting, anti-inflammatory, and neuroprotective properties, I. tinctoria could be used to treat depression, anxiety, and stress resistance. Hence, the present study is aimed at delineating whether administration of I. tinctoria leaf extract may improve stress-induced disorders in mice. A set of four behavioral tests was selected that together are suitable for phenotyping acute restraint stress-associated behaviors in mice, namely locomotor activity, social integration, dark/light box, and splash tests. The plasma and brains were collected. A brain-derived neurotrophic factor, tumor necrosis factor-alpha, C-reactive protein, corticosterone, NO, reactive oxygen species levels, superoxide dismutase and catalase activity, and ferric-reducing antioxidant power were measured. In mice stressed by immobilization, decreased locomotor activity, anxiety-like behavior, and contact with other individuals were observed, as well as increased oxidative stress and increased levels of nitric oxide in the brain and plasma C-reactive protein. A single administration of I. tinctoria leaf extract was able to reverse the behavioral response to restraint by a mechanism partially dependent on the modulation of oxidative stress, neuroinflammation, and NO reduction. In conclusion, Isatis tinctoria hydroalcoholic leaf extract can reduce stress-induced behavioral disturbances by regulating neurooxidative, neuronitrosative, and neuroimmune pathways. Therefore, it could be recommended for further research on clinical efficacy in depression and anxiety disorder treatment.

Comparative Study of the Results of Operations in Patients with Tumor and Non-Tumor Obstructive Jaundice Who Received and Did Not Receive Antioxidant Therapy for the Correction of Endotoxemia, Glycolysis, and Oxidative Stress

Purpose: To compare the results of surgical treatment and changes in biomarkers of cholestasis, endotoxicosis, cytolysis, lipid peroxidation, glycolysis disorders, and inflammation in patients with benign and malignant obstructive jaundice (OJ) in patients receiving and not receiving antioxidant pharmacotherapy (AOT). Patients and methods: The study included 113 patients (aged 21–90 years; 47 males and 66 females) who received surgical intervention for OJ due to non-malignant (71%) or malignant tumor (29%) etiologies. Patients were divided into two groups: Group I (n = 61) who did not receive AOT and Group II (n = 51) who received AOT (succinate-containing drug Reamberin) as part of detoxification infusion therapy. The surgical approach and scope of interventions in both groups were identical. Dynamic indicators of endotoxicosis, cholestasis, and cytolysis (total, direct, and indirect bilirubin, alanine aminotransferase [ALT], aspartate aminotransferase [AST], alkaline phosphatase [AP] and gamma-glutamyltransferase [GGT]), kidney function (urea), lipid peroxidation (malonic dialdehyde, MDA), inflammation (leukocytosis), and glycolysis disorders (lactate dehydrogenase (LDH), glucose) were evaluated. Results: Tumor jaundice, unlike non-tumor jaundice, persisted and was characterized by a more severe course, a higher level of hyperbilirubinemia, and lipid peroxidation. The prognostic value of the direct (and total) bilirubin, MDA, glycemia, and leukocytosis levels on the day of hospitalization, which increased significantly in severe jaundice and, especially, in deceased patients, was established. Decompression interventions significantly reduced levels of markers of liver failure, cytolysis, cholestasis, and lipid peroxidation on day 3 after decompression by 1.5–3 times from initial levels; this is better achieved in non-tumor OJ. However, 8 days after decompression, most patients did not normalize the parameters studied in both groups. AOT favorably influenced the dynamics (on day 8 after decompression) of total and direct bilirubin, ALT, AST, MDA, and leukocytosis in non-tumor jaundice, as well as the dynamics of direct bilirubin, AST, MDA, glucose, and LDH in tumor jaundice. Clinically, in the AOT group, a two-fold reduction in the operative and non-operative complications was recorded (from 23% to 11.5%), a reduction in the duration of biliary drainage by 30%, the length of stay in intensive care units was reduced by 5 days, and even hospital mortality decreased, especially in malignancy-induced OJ. Conclusion: A mechanism for the development of liver failure in OJ is oxidative stress with the appearance of enhanced lipid peroxidation and accompanied by hepatocyte necrosis. Inclusion of AOT in perioperative treatment in these patients improves treatment outcomes.

Altered central and blood glutathione in Alzheimer's disease and mild cognitive impairment: a meta-analysis

BACKGROUND

Increasing evidence implicates oxidative stress (OS) in Alzheimer disease (AD) and mild cognitive impairment (MCI). Depletion of the brain antioxidant glutathione (GSH) may be important in OS-mediated neurodegeneration, though studies of post-mortem brain GSH changes in AD have been inconclusive. Recent in vivo measurements of the brain and blood GSH may shed light on GSH changes earlier in the disease.

AIM

To quantitatively review in vivo GSH in AD and MCI compared to healthy controls (HC) using meta-analyses.

METHOD

Studies with in vivo brain or blood GSH levels in MCI or AD with a HC group were identified using MEDLINE, PsychInfo, and Embase (1947-June 2020). Standardized mean differences (SMD) and 95% confidence intervals (CI) were calculated for outcomes using random effects models. Outcome measures included brain GSH (Meshcher-Garwood Point Resolved Spectroscopy (MEGA-PRESS) versus non-MEGA-PRESS) and blood GSH (intracellular versus extracellular) in AD and MCI. The Q statistic and Egger's test were used to assess heterogeneity and risk of publication bias, respectively.

RESULTS

For brain GSH, 4 AD (AD=135, HC=223) and 4 MCI (MCI=213, HC=211) studies were included. For blood GSH, 26 AD (AD=1203, HC=1135) and 7 MCI (MCI=434, HC=408) studies were included. Brain GSH overall did not differ in AD or MCI compared to HC; however, the subgroup of studies using MEGA-PRESS reported lower brain GSH in AD (SMD [95%CI] -1.45 [-1.83, -1.06], p<0.001) and MCI (-1.15 [-1.71, -0.59], z=4.0, p<0.001). AD had lower intracellular and extracellular blood GSH overall (-0.87 [-1. 30, -0.44], z=3.96, p<0.001). In a subgroup analysis, intracellular GSH was lower in MCI (-0.66 [-1.11, -0.21], p=0.025). Heterogeneity was observed throughout (I² >85%) and not fully accounted by subgroup analysis. Egger's test indicated risk of publication bias.

CONCLUSION

Blood intracellular GSH decrease is seen in MCI, while both intra- and extracellular decreases were seen in AD. Brain GSH is decreased in AD and MCI in subgroup analysis. Potential bias and heterogeneity suggest the need for measurement standardization and additional studies to explore sources of heterogeneity.

Antioxidants in Alzheimer's Disease: Current Therapeutic Significance and Future Prospects

Alzheimer's disease (AD) rate is accelerating with the increasing aging of the world's population. The World Health Organization (WHO) stated AD as a global health priority. According to the WHO report, around 82 million people in 2030 and 152 million in 2050 will develop dementia (AD contributes 60% to 70% of cases), considering the current scenario. AD is the most common neurodegenerative disease, intensifying impairments in cognition, behavior, and memory. Histopathological AD variations include extracellular senile plaques' formation, tangling of intracellular neurofibrils, and synaptic and neuronal loss in the brain. Multiple evidence directly indicates that oxidative stress participates in an early phase of AD before cytopathology. Moreover, oxidative stress is induced by almost all misfolded protein lumps like α-synuclein, amyloid-β, and others. Oxidative stress plays a crucial role in activating and causing various cell signaling pathways that result in lesion formations of toxic substances, which foster the development of the disease. Antioxidants are widely preferred to combat oxidative stress, and those derived from natural sources, which are often incorporated into dietary habits, can play an important role in delaying the onset as well as reducing the progression of AD. However, this approach has not been extensively explored yet. Moreover, there has been growing evidence that a combination of antioxidants in conjugation with a nutrient-rich diet might be more effective in tackling AD pathogenesis. Thus, considering the above-stated fact, this comprehensive review aims to elaborate the basics of AD and antioxidants, including the vitality of antioxidants in AD. Moreover, this review may help researchers to develop effectively and potentially improved antioxidant therapeutic strategies for this disease as it also deals with the clinical trials in the stated field.

Cognitive enhancement and neuroprotective effects of OABL, a sesquiterpene lactone in 5xFAD Alzheimer's disease mice model

Alzheimer's disease (AD) is a neurodegenerative disease in which oxidative stress and neuroinflammation were demonstrated to be associated with neuronal loss and cognitive deficits. However, there are still no specific treatments that can prevent the progression of AD. In this study, a screening of anti-inflammatory hits from 4207 natural compounds of two different molecular libraries indicated 1,6-O,O-diacetylbritannilactone (OABL), a 1,10-seco-eudesmane sesquiterpene lactone isolated from the herb Inula britannica L., exhibited strong anti-inflammatory activity in vitro as well as favorable BBB penetration property. OABL reduced LPS-induced neuroinflammation in BV-2 microglial cells as assessed by effects on the levels of inflammatory mediators including NO, PGE₂, TNF-α, iNOS, and COX-2, as well as the translocation of NF-κB. Besides, OABL also exhibited pronounced neuroprotective effects against oxytosis and ferroptosis in the rat pheochromocytoma PC12 cell line. For in vivo research, OABL (20 mg/kg B.W., i.p.) for 21 d attenuated the impairments in cognitive function observed in 6-month-old 5xFAD mice, as assessed with the Morris water maze test. OABL restored neuronal damage and postsynaptic density protein 95 (PSD95) expression in the hippocampus. OABL also significantly reduced the accumulation of amyloid plaques, the Aβ expression, the phosphorylation of Tau protein, and the expression of BACE1 in AD mice brain. In addition, OABL attenuated the overactivation of microglia and astrocytes by suppressing the expressions of inflammatory cytokines, and increased glutathione (GSH) and reduced malondialdehyde (MDA) and super oxide dismutase (SOD) levels in the 5xFAD mice brain. In conclusion, these results highlight the beneficial effects of the natural product OABL as a novel treatment with potential application for drug discovery in AD due to its pharmacological profile.

Is There Any Relationship Between Biochemical Indices and Anthropometric Measurements With Dorsolateral Prefrontal Cortex Activation Among Older Adults With Mild Cognitive Impairment?

Working memory is developed in one region of the brain called the dorsolateral prefrontal cortex (DLPFC). The dysfunction of this region leads to synaptic neuroplasticity impairment. It has been reported that several biochemical parameters and anthropometric measurements play a vital role in cognition and brain health. This study aimed to investigate the relationships between cognitive function, serum biochemical profile, and anthropometric measurements using DLPFC activation. A cross-sectional study was conducted among 35 older adults (≥60 years) who experienced mild cognitive impairment (MCI). For this purpose, we distributed a comprehensive interview-based questionnaire for collecting sociodemographic information from the participants and conducting cognitive tests. Anthropometric values were measured, and fasting blood specimens were collected. We investigated their brain activation using the task-based functional MRI (fMRI; N-back), specifically in the DLPFC region. Positive relationships were observed between brain-derived neurotrophic factor (BDNF) (β = 0.494, p &lt; 0.01) and Mini-Mental State Examination (MMSE) (β = 0.698, p &lt; 0.01); however, negative relationships were observed between serum triglyceride (β = −0.402, p &lt; 0.05) and serum malondialdehyde (MDA) (β = −0.326, p &lt; 0.05) with right DLPFC activation (R2 = 0.512) while the participants performed 1-back task after adjustments for age, gender, and years of education. In conclusion, higher serum triglycerides, higher oxidative stress, and lower neurotrophic factor were associated with lower right DLPFC activation among older adults with MCI. A further investigation needs to be carried out to understand the causal-effect mechanisms of the significant parameters and the DLPFC activation so that better intervention strategies can be developed for reducing the risk of irreversible neurodegenerative diseases among older adults with MCI.

Magnolol attenuates the locomotor impairment, cognitive deficit, and neuroinflammation in Alzheimer's disease mice with brain insulin resistance via up-regulating miR-200c

In this study, we aimed to investigate the effect of Magnolol on Alzheimer’s disease (AD). After the model of streptozotocin-induced AD mice with brain insulin resistance was established, the mice were treated with Magnolol or miR-200c antagomiR. The abilities of ambulations, rearings, discrimination, spatial learning, and memory were evaluated by open-field test (OFT), novel object recognition (NOR), and morris water maze (MWM) tests. The levels of malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), C-reactive protein (CRP), and miR-200c in the mice hippocampus were evaluated by enzyme-linked immunosorbent assay, Western blot, or Quantitative real-time Polymerase Chain Reaction. In AD mice model, streptozotocin induced the locomotor impairment and cognitive deficit, up-regulated levels of MDA, TNF-α, IL-6, and CRP, while down-regulated levels of GSH, SOD, and miR-200c. Magnolol increased the rearings numbers and discrimination index of AD mice in OFT and NOR tests. Magnolol increased the number of entries in the target quadrant and time spent in the target quadrant and decreased the escape latency of AD mice in the MWM test. Magnolol also down-regulated the levels of MDA, TNF-α, IL-6, and CRP, and up-regulated the levels of GSH, SOD, and miR-200c in the hippocampus tissues of AD mice. However, miR-200c antagomiR did the opposite and further offset the effects of the Magnolol on AD mice. Magnolol attenuated the locomotor impairment, cognitive deficit, and neuroinflammatory in AD mice with brain insulin resistance via up-regulating miR-200c.

Neuronal ROS-induced glial lipid droplet formation is altered by loss of Alzheimer's disease-associated genes

A growing list of Alzheimer's disease (AD) genetic risk factors is being identified, but the contribution of each variant to disease mechanism remains largely unknown. We have previously shown that elevated levels of reactive oxygen species (ROS) induces lipid synthesis in neurons leading to the sequestration of peroxidated lipids in glial lipid droplets (LD), delaying neurotoxicity. This neuron-to-glia lipid transport is APOD/E-dependent. To identify proteins that modulate these neuroprotective effects, we tested the role of AD risk genes in ROS-induced LD formation and demonstrate that several genes impact neuroprotective LD formation, including homologs of human ABCA1, ABCA7, VLDLR, VPS26, VPS35, AP2A, PICALM, and CD2AP Our data also show that ROS enhances Aβ42 phenotypes in flies and mice. Finally, a peptide agonist of ABCA1 restores glial LD formation in a humanized APOE4 fly model, highlighting a potentially therapeutic avenue to prevent ROS-induced neurotoxicity. This study places many AD genetic risk factors in a ROS-induced neuron-to-glia lipid transfer pathway with a critical role in protecting against neurotoxicity.

Role of Oxidative Damage in Alzheimer's Disease and Neurodegeneration: From Pathogenic Mechanisms to Biomarker Discovery

Alzheimer’s disease (AD) is a neurodegenerative disorder accounting for over 50% of all dementia patients and representing a leading cause of death worldwide for the global ageing population. The lack of effective treatments for overt AD urges the discovery of biomarkers for early diagnosis, i.e., in subjects with mild cognitive impairment (MCI) or prodromal AD. The brain is exposed to oxidative stress as levels of reactive oxygen species (ROS) are increased, whereas cellular antioxidant defenses are decreased. Increased ROS levels can damage cellular structures or molecules, leading to protein, lipid, DNA, or RNA oxidation. Oxidative damage is involved in the molecular mechanisms which link the accumulation of amyloid-β and neurofibrillary tangles, containing hyperphosphorylated tau, to microglia response. In this scenario, microglia are thought to play a crucial role not only in the early events of AD pathogenesis but also in the progression of the disease. This review will focus on oxidative damage products as possible peripheral biomarkers in AD and in the preclinical phases of the disease. Particular attention will be paid to biological fluids such as blood, CSF, urine, and saliva, and potential future use of molecules contained in such body fluids for early differential diagnosis and monitoring the disease course. We will also review the role of oxidative damage and microglia in the pathogenesis of AD and, more broadly, in neurodegeneration.

Serum metabolomics of Bama miniature pigs bitten by Bungarus multicinctus

Bungarus multicinctus is one of the top ten venomous snakes in China, and its bite causes acute and severe diseases, but its pathophysiology remains poorly elucidated. Thus, an animal model of Bungarus multicinctus bite was established by intramuscular injection of 30μg/kg of Bungarus multicinctus venom, and then the serum metabolites were subsequently screened, identified and validated by ultra-performance liquid chromatography-quadrupole-time of flight-mass spectrometry (UPLC-Q-TOF-MS) methods to explore the potential biomakers and possible metabolic pathways. Untargeted metabolomics analysis showed that 36 and 38 endogenous metabolites levels changed in ESI+ and ESI-, respectively, KEGG pathway analysis showed that 5 metabolic pathways, including mineral absorption, central carbon metabolism in cancer, protein digestion and absorption, aminoacyl-tRNA biosynthesis and ABC transporters might be closely related to Bungarus multicinctus bite. Targeted metabolomics analysis showed that there were significant differences in serum D-proline, L-leucine and L-glutamine after Bungarus multicinctus bite (P < 0.05). In addition, receiver operating characteristic (ROC) analysis showed that the diagnostic efficiency of L-Glutamine was superior to other potential biomarkers and the AUC value was 0.944. Moreover, we found evidence for differences in the pathophysiology of glutamine between Bungarus multicinctus bite group and normal group, specifically with the content of glutamine synthetase (GS) and glutaminase (GLS). Taken together, the current study has successfully established an animal model of Bungarus multicinctus bite, and further identified the links between the metabolic perturbations and the pathophysiology and the potential diagnostic biomakers of Bungarus multicinctus bite, which provided valuable insights for studying the mechanism of Bungarus multicinctus bite.

Estimated Phytate Intake Is Associated with Improved Cognitive Function in the Elderly, NHANES 2013-2014

Phytate, an antioxidant, may improve cognition by inhibiting iron catalyzed hydroxyl radical formation. Particularly in the elderly, this provides a potential dietary approach for mitigating age-related brain neuronal dysfunction and loss. In this study, we investigated the relationship between phytate intake and cognitive function in the elderly. We used data from the 2013-2014 National Health and Nutrition Examination Survey (NHANES) and the corresponding Food Patterns Equivalents Database (FPED). Phytate content of food groups from published data were merged with the appropriate FPED data to estimate the total phytate intake for each subject. Principal component analysis was used to develop a composite score from four cognitive function scores in NHANES data, and regression analysis was used to determine the relationship between this score and phytate intake. Median phytate intake was 0.65 (0.61, 0.71) g/day. It was low among females, non-Hispanic blacks, and people with history of at least one chronic disease (p < 0.05). In regression analysis adjusted for confounders, phytate intake was positively associated with cognitive function (β (95% CI) = 1.90 (0.73-3.07); p = 0.015). These results suggest that phytate may be associated with improved cognition, hence the need to consider including phytate-rich foods in the diet among the elderly.

The Influence of Serum Uric Acid Level on Alzheimer's Disease: A Narrative Review

As a powerful antioxidant in the human body, uric acid (UA) has been the subject of increasing research that focused on its influence on Alzheimer's disease (AD) in recent years. The latest literature was gathered to describe the influence of serum uric acid (SUA) level on the onset and progression of AD and to analyze the possibility that SUA is a biomarker of Alzheimer's disease. A large number of existing studies suggested that the SUA level was lower or tended to decrease in patients with AD, and increased SUA level may have a protective effect in AD, which could reduce the risk of onset and slowing the course of the disease. However, some Mendelian randomization analyses suggested that genetically determined uric acid was not associated with AD risk. Existing research results are contradictory due to the high inconsistency of the studies, the selection of subjects, and other factors. UA also showed a strong association with cognitive function, and there appeared to be a gender-selective neuroprotective action. Due to its potent antioxidant properties, the low uric acid level may contribute to oxidative stress to accelerate disease progression. But some preclinical data showed a possibility that in some special cases, UA had a prooxidant properties. The possibility was raised in the discussion of the underlying mechanism that both the low uric acid level and the rapidly progressive course of the disease were the consequence of malnutrition. This paper reviews recent advances in the study of SUA and AD which offers the possibility of new biomarker, new prevention, and treatment strategies for Alzheimer's disease.

Genetic Editing and Pharmacogenetics in Current And Future Therapy Of Neurocognitive Disorders

Dementia is an important issue in western societies, and in the following years, this problem will also rise in the developing regions, such as Africa and Asia. The most common types of dementia in adults are Alzheimer's Disease (AD), Dementia with Lewy Bodies (DLB), Frontotemporal Dementia (FTD) and Vascular Dementia (VaD), of which, AD accounts for more than half of the cases. The most prominent symptom of AD is cognitive impairment, currently treated with four drugs: Donepezil, rivastigmine, and galantamine, enhancing cholinergic transmission; as well as memantine, protecting neurons against glutamate excitotoxicity. Despite ongoing efforts, no new drugs in the treatment of AD have been registered for the last ten years, thus multiple studies have been conducted on genetic factors affecting the efficacy of antidementia pharmacotherapy. The researchers investigate the effects of variants in multiple genes, such as ABCB1, ACE, CHAT, CHRNA7, CYP2C9, CYP2C19, CYP2D6, CYP3A4, CYP3A5, CYP3A7, NR1I2, NR1I3, POR, PPAR, RXR, SLC22A1/2/5, SLC47A1, UGT1A6, UGT1A9 and UGT2B7, associated with numerous pathways: the development of pathological proteins, formation and metabolism of acetylcholine, transport, metabolism and excretion of antidementia drugs and transcription factors regulating the expression of genes responsible for metabolism and transport of drugs. The most promising results have been demonstrated for APOE E4, dementia risk variant, BCHE-K, reduced butyrylcholinesterase activity variant, and CYP2D6 UM, ultrarapid hepatic metabolism. Further studies investigate the possibilities of the development of emerging drugs or genetic editing by CRISPR/Cas9 for causative treatment. In conclusion, the pharmacogenetic studies on dementia diseases may improve the efficacy of pharmacotherapy in some patients with beneficial genetic variants, at the same time, identifying the carriers of unfavorable alleles, the potential group of novel approaches to the treatment and prevention of dementia.

Neuroprotective Effects of Acrocomia aculeata Pulp Oil Microcapsules on Rats Subjected to Chronic Stress

Acrocomia aculeata fruits are rich in monounsaturated fatty acid, β-carotene, tocopherol, and other antioxidant compounds. The aim of our study was to investigate and compare the protective effects of A. aculeata pulp oil and microencapsulated pulp oil on brain oxidative damage induced by chronic restraint stress (CRS) in rats (cortex, hippocampus, and striatum). Thirty-six Wistar rats were divided into six treatment groups: C, P, and M groups received 1 μL/g of body weight of distilled water, pulp oil, and pulp oil microcapsules by daily gavage, respectively. The SC, SP, and SM groups received 1 μL/g of body weight of distilled water, pulp oil, and pulp oil microcapsules by daily gavage, respectively, and were then subjected to uninterrupted 6 h of CRS. After 21 days of testing, the rats were euthanized and the brain tissue of the groups was removed for evaluation for oxidative damage markers and antioxidant enzymes. Endpoints of oxidative stress (OS) markers (lipid peroxidation, protein carbonylation, and reduced glutathione [GSH]) and antioxidant enzymes (superoxide dismutase and catalase) were evaluated. By imposing chronic stress on rats, pulp oil and microcapsules of pulp oil induced positive antioxidant responses, mainly by increasing the GSH content, increasing the ability of neural tissues to deal with inherent OS, thus protecting against neurodegenerative diseases. The administration of A. aculeata pulp oil and microencapsulated pulp oil made the reversal of the oxidant parameters, which may protect the brain tissue of rats altered by CRS. The Clinical Trial Registration number: n° 1.008/2018 CEUA/UFMS.

Exosomal Aβ-Binding Proteins Identified by "In Silico" Analysis Represent Putative Blood-Derived Biomarker Candidates for Alzheimer´s Disease

The potential of exosomes as biomarker resources for diagnostics and even for therapeutics has intensified research in the field, including in the context of Alzheimer´s disease (AD). The search for disease biomarkers in peripheral biofluids is advancing mainly due to the easy access it offers. In the study presented here, emphasis was given to the bioinformatic identification of putative exosomal candidates for AD. The exosomal proteomes of cerebrospinal fluid (CSF), serum and plasma, were obtained from three databases (ExoCarta, EVpedia and Vesiclepedia), and complemented with additional exosomal proteins already associated with AD but not found in the databases. The final biofluids’ proteomes were submitted to gene ontology (GO) enrichment analysis and the exosomal Aβ-binding proteins that can constitute putative candidates were identified. Among these candidates, gelsolin, a protein known to be involved in inhibiting Abeta fibril formation, was identified, and it was tested in human samples. The levels of this Aβ-binding protein, with anti-amyloidogenic properties, were assessed in serum-derived exosomes isolated from controls and individuals with dementia, including AD cases, and revealed altered expression patterns. Identification of potential peripheral biomarker candidates for AD may be useful, not only for early disease diagnosis but also in drug trials and to monitor disease progression, allowing for a timely therapeutic intervention, which will positively impact the patient’s quality of life.

A Highly Selective In Vitro JNK3 Inhibitor, FMU200, Restores Mitochondrial Membrane Potential and Reduces Oxidative Stress and Apoptosis in SH-SY5Y Cells

Current treatments for neurodegenerative diseases (ND) are symptomatic and do not affect disease progression. Slowing this progression remains a crucial unmet need for patients and their families. c-Jun N-terminal kinase 3 (JNK3) are related to several ND hallmarks including apoptosis, oxidative stress, excitotoxicity, mitochondrial dysfunction, and neuroinflammation. JNK inhibitors can play an important role in addressing neuroprotection. This research aims to evaluate the neuroprotective, anti-inflammatory, and antioxidant effects of a synthetic compound (FMU200) with known JNK3 inhibitory activity in SH-SY5Y and RAW264.7 cell lines. SH-SY5Y cells were pretreated with FMU200 and cell damage was induced by 6-hydroxydopamine (6-OHDA) or hydrogen peroxide (H₂O₂). Cell viability and neuroprotective effect were assessed with an MTT assay. Flow cytometric analysis was performed to evaluate cell apoptosis. The H₂O₂-induced reactive oxygen species (ROS) generation and mitochondrial membrane potential (ΔΨm) were evaluated by DCFDA and JC-1 assays, respectively. The anti-inflammatory effect was determined in LPS-induced RAW264.7 cells by ELISA assay. In undifferentiated SH-SY5Y cells, FMU200 decreased neurotoxicity induced by 6-OHDA in approximately 20%. In RA-differentiated cells, FMU200 diminished cell death in approximately 40% and 90% after 24 and 48 h treatment, respectively. FMU200 reduced both early and late apoptotic cells, decreased ROS levels, restored mitochondrial membrane potential, and downregulated JNK phosphorylation after H₂O₂ exposure. In LPS-stimulated RAW264.7 cells, FMU200 reduced TNF-α levels after a 3 h treatment. FMU200 protects neuroblastoma SH-SY5Y cells against 6-OHDA- and H₂O₂-induced apoptosis, which may result from suppressing the JNK pathways. Our findings show that FMU200 can be a useful candidate for the treatment of neurodegenerative disorders.

Common and Novel Markers for Measuring Inflammation and Oxidative Stress Ex Vivo in Research and Clinical Practice-Which to Use Regarding Disease Outcomes?

Many chronic conditions such as cancer, chronic obstructive pulmonary disease, type-2 diabetes, obesity, peripheral/coronary artery disease and auto-immune diseases are associated with low-grade inflammation. Closely related to inflammation is oxidative stress (OS), which can be either causal or secondary to inflammation. While a low level of OS is physiological, chronically increased OS is deleterious. Therefore, valid biomarkers of these signalling pathways may enable detection and following progression of OS/inflammation as well as to evaluate treatment efficacy. Such biomarkers should be stable and obtainable through non-invasive methods and their determination should be affordable and easy. The most frequently used inflammatory markers include acute-phase proteins, essentially CRP, serum amyloid A, fibrinogen and procalcitonin, and cytokines, predominantly TNFα, interleukins 1β, 6, 8, 10 and 12 and their receptors and IFNγ. Some cytokines appear to be disease-specific. Conversely, OS-being ubiquitous-and its biomarkers appear less disease or tissue-specific. These include lipid peroxidation products, e.g., F2-isoprostanes and malondialdehyde, DNA breakdown products (e.g., 8-OH-dG), protein adducts (e.g., carbonylated proteins), or antioxidant status. More novel markers include also -omics related ones, as well as non-invasive, questionnaire-based measures, such as the dietary inflammatory-index (DII), but their link to biological responses may be variable. Nevertheless, many of these markers have been clearly related to a number of diseases. However, their use in clinical practice is often limited, due to lacking analytical or clinical validation, or technical challenges. In this review, we strive to highlight frequently employed and useful markers of inflammation-related OS, including novel promising markers.

A review on α-mangostin as a potential multi-target-directed ligand for Alzheimer's disease

Alzheimer's disease (AD) is an age-related neurodegenerative disease characterized by progressive memory loss, declining language skills and other cognitive disorders. AD has brought great mental and economic burden to patients, families and society. However due to the complexity of AD's pathology, drugs developed for the treatment of AD often fail in clinical or experimental trials. The main problems of current anti-AD drugs are low efficacy due to mono-target method or side effects, especially high hepatotoxicity. To tackle these two main problems, multi-target-directed ligand (MTDL) based on "one molecule, multiple targets" has been studied. MTDLs can regulate multiple biological targets at the same time, so it has shown higher efficacy, better safety. As a natural active small molecule, α-mangostin (α-M) has shown potential multi-factor anti-AD activities in a series of studies, furthermore it also has a certain hepatoprotective effect. The good availability of α-M also provides support for its application in clinical research. In this work, multiple activities of α-M related to AD therapy were reviewed, which included anti-cholinesterase, anti-amyloid-cascade, anti-inflammation, anti-oxidative stress, low toxicity, hepatoprotective effects and drug formulation. It shows that α-M is a promising candidate for the treatment of AD.

Rhodiola crenulata protects against Alzheimer's disease in rats: A brain lipidomics study by Fourier-transform ion cyclotron resonance mass spectrometry coupled with high-performance reversed-phase liquid chromatography and hydrophilic interaction liquid chromatography

RATIONALE

Alzheimer's disease (AD) is a chronic, severe, progressive neurodegenerative disorder associated with cognitive and memory impairment that ultimately causes death. Most approved drugs can only alleviate some of the symptoms of AD, but no interventions have been found that reverse the underlying disease mechanisms. Rhodiola crenulata extract (RCE) has been reported to alleviate AD symptoms in rats. However, its underlying mechanism of action is still unclear.

METHODS

A brain lipidomics study was conducted to investigate the protective effects of RCE against AD in rats to identify potential biomarkers of AD using Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) coupled with high-performance reversed-phase liquid chromatography (RPLC) and hydrophilic interaction liquid chromatography (HILIC). Differences in lipid metabolism profiles were evaluated using multivariate statistical analysis. Finally, the possible mechanism of action of RCE on AD was investigated by analysing metabolic pathways.

RESULTS

The RPLCHILIC/FT-ICR MS results showed 20 lipid components with significant differences between the control and model groups. After administration of RCE, the levels of 10 lipids in AD rats tended to shift toward reference levels. The pathway analysis revealed that the protective effect of RCE against AD might be related to regulation of glycerophospholipid metabolism.

CONCLUSIONS

This study provides a novel perspective on the potential intervention mechanism of RCE in the treatment of AD.

Prolonged Treatment with Centella asiatica Improves Memory, Reduces Amyloid-β Pathology, and Activates NRF2-Regulated Antioxidant Response Pathway in 5xFAD Mice

BACKGROUND

The medicinal herb Centella asiatica has been long been used for its neuroprotective and cognitive enhancing effects. We have previously shown that two weeks of treatment with a water extract of Centella asiatica (CAW) improves cognition and activates the endogenous antioxidant response pathway without altering amyloid-β (Aβ) plaque burden.

OBJECTIVE

Here, we assess the effect of long-term treatment of CAW in the 5xFAD mouse model of Aβ accumulation.

METHODS

Four-month-old 5xFAD mice were treated with CAW in their drinking water (2 g/L) for three months at which point they underwent cognitive testing as well as analysis of Aβ plaque levels and antioxidant and synaptic gene expression. In order to confirm the involvement of the antioxidant regulatory transcription factor NRF2 on the effects of CAW on synaptic plasticity, neurons isolated from 5xFAD mice were also treated with CAW and the targeted inhibitor ML385.

RESULTS

Three months of treatment with CAW improved spatial and contextual memory as well as executive function in 5xFAD mice. This improvement was accompanied by increased antioxidant gene expression and a decrease in Aβ plaque burden relative to untreated 5xFAD animals. In isolated neurons, treatment with ML385 blocked the effects of CAW on dendritic arborization and synaptic gene expression.

CONCLUSION

These results suggest that prolonged CAW exposure could be beneficial in Alzheimer's disease and that these effects likely involve NRF2 activation. Moreover, these findings suggest that targeting NRF2 itself may be a relevant therapeutic strategy for improving synaptic plasticity and cognitive function in Alzheimer's disease.

Environmental Nanoparticles, SARS-CoV-2 Brain Involvement, and Potential Acceleration of Alzheimer's and Parkinson's Diseases in Young Urbanites Exposed to Air Pollution

Alzheimer's and Parkinson's diseases (AD, PD) have a pediatric and young adult onset in Metropolitan Mexico City (MMC). The SARS-CoV-2 neurotropic RNA virus is triggering neurological complications and deep concern regarding acceleration of neuroinflammatory and neurodegenerative processes already in progress. This review, based on our MMC experience, will discuss two major issues: 1) why residents chronically exposed to air pollution are likely to be more susceptible to SARS-CoV-2 systemic and brain effects and 2) why young people with AD and PD already in progress will accelerate neurodegenerative processes. Secondary mental consequences of social distancing and isolation, fear, financial insecurity, violence, poor health support, and lack of understanding of the complex crisis are expected in MMC residents infected or free of SARS-CoV-2. MMC residents with pre-SARS-CoV-2 accumulation of misfolded proteins diagnostic of AD and PD and metal-rich, magnetic nanoparticles damaging key neural organelles are an ideal host for neurotropic SARS-CoV-2 RNA virus invading the body through the same portals damaged by nanoparticles: nasal olfactory epithelium, the gastrointestinal tract, and the alveolar-capillary portal. We urgently need MMC multicenter retrospective-prospective neurological and psychiatric population follow-up and intervention strategies in place in case of acceleration of neurodegenerative processes, increased risk of suicide, and mental disease worsening. Identification of vulnerable populations and continuous effort to lower air pollution ought to be critical steps.