Regional vulnerability to lipoxidative damage and inflammation in normal human brain aging

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.

Cellular mechanisms in brain aging: Focus on physiological and pathological aging

Aging is a natural phenomenon characterized by accumulation of cellular damage and debris. Oxidative stress, cellular senescence, sustained inflammation, and DNA damage are the main cellular processes characteristic of aging associated with morphological and functional decline. These effects tend to be more pronounced in tissues with high metabolic rates such as the brain, mainly in regions such as the prefrontal cortex, hippocampus, and amygdala. These regions are highly related to cognitive behavior, and therefore their atrophy usually leads to decline in processes such as memory and learning. These cognitive declines can occur in physiological aging and are exacerbated in pathological aging. In this article, we review the cellular processes that underlie the triggers of aging and how they relate to one another, causing the atrophy of nerve tissue that is typical of aging. The main topic of this review to determine the central factor that triggers all the cellular processes that lead to cellular aging and discriminate between normal and pathological aging. Finally, we review how the use of supplements with antioxidant and anti-inflammatory properties reduces the cognitive decline typical of aging, which reinforces the hypothesis of oxidative stress and cellular damage as contributors of physiological atrophy of aging. Moreover, cumulative evidence suggests their possible use as therapies, which improve the aging population's quality of life.

Docosahexaenoic acid enhances hippocampal insulin sensitivity to promote cognitive function of aged rats on a high-fat diet

INTRODUCTION

Diminished brain insulin sensitivity is associated with reduced cognitive function. Docosahexaenoic acid (DHA) is known to maintain normal brain function.

OBJECTIVES

This study aimed to determine whether DHA impacts hippocampal insulin sensitivity and cognitive function in aged rats fed a high-fat diet (HFD).

METHODS

Eight-month-old female Sprague-Dawley rats were randomly divided into three groups (n = 50 each). Rats in the aged group, HFD group, and DHA treatment group received standard diet (10 kcal% fat), HFD (45 kcal% fat), and DHA-enriched HFD (45 kcal% fat, 1% DHA, W/W) for 10 months, respectively. Four-month-old female rats (n = 40) that received a standard diet served as young controls. Neuroinflammation, oxidative stress, amyloid formation, and tau phosphorylation in the hippocampus, as well as systemic glucose homeostasis and cognitive function, were tested.

RESULTS

DHA treatment relieved a block in the insulin signaling pathway and consequently protected aged rats against HFD-induced hippocampal insulin resistance. The beneficial effects were explained by a DHA-induced decrease in systemic glucose homeostasis dysregulation, hippocampal neuroinflammation and oxidative stress. In addition, DHA treatment broke the reciprocal cycle of hippocampal insulin resistance, Aβ burden, and tau hyperphosphorylation. Importantly, treatment of model rats with DHA significantly increased their cognitive capacity, as evidenced by their increased hippocampal-dependent learning and memory, restored neuron morphology, enhanced cholinergic activity, and activated cyclic AMP-response element-binding protein.

CONCLUSION

DHA improves cognitive function by enhancing hippocampal insulin sensitivity.

COX-2/sEH Dual Inhibitor Alleviates Hepatocyte Senescence in NAFLD Mice by Restoring Autophagy through Sirt1/PI3K/AKT/mTOR

We previously found that the disorder of soluble epoxide hydrolase (sEH)/cyclooxygenase-2 (COX-2)-mediated arachidonic acid (ARA) metabolism contributes to the pathogenesis of the non-alcoholic fatty liver disease (NAFLD) in mice. However, the exact mechanism has not been elucidated. Accumulating evidence points to the essential role of cellular senescence in NAFLD. Herein, we investigated whether restoring the balance of sEH/COX-2-mediated ARA metabolism attenuated NAFLD via hepatocyte senescence. A promised dual inhibitor of sEH and COX-2, PTUPB, was used in our study to restore the balance of sEH/COX-2-mediated ARA metabolism. In vivo, NAFLD was induced by a high-fat diet (HFD) using C57BL/6J mice. In vitro, mouse hepatocytes (AML12) and mouse hepatic astrocytes (JS1) were used to investigate the effects of PTUPB on palmitic acid (PA)-induced hepatocyte senescence and its mechanism. PTUPB alleviated liver injury, decreased collagen and lipid accumulation, restored glucose tolerance, and reduced hepatic triglyceride levels in HFD-induced NAFLD mice. Importantly, PTUPB significantly reduced the expression of liver senescence-related molecules p16, p53, and p21 in HFD mice. In vitro, the protein levels of γH2AX, p53, p21, COX-2, and sEH were increased in AML12 hepatocytes treated with PA, while Ki67 and PCNA were significantly decreased. PTUPB decreased the lipid content, the number of β-gal positive cells, and the expression of p53, p21, and γH2AX proteins in AML12 cells. Meanwhile, PTUPB reduced the activation of hepatic astrocytes JS1 by slowing the senescence of AML12 cells in a co-culture system. It was further observed that PTUPB enhanced the ratio of autophagy-related protein LC3II/I in AML12 cells, up-regulated the expression of Fundc1 protein, reduced p62 protein, and suppressed hepatocyte senescence. In addition, PTUPB enhanced hepatocyte autophagy by inhibiting the PI3K/AKT/mTOR pathway through Sirt1, contributing to the suppression of senescence. PTUPB inhibits the PI3K/AKT/mTOR pathway through Sirt1, improves autophagy, slows down the senescence of hepatocytes, and alleviates NAFLD.

Autoantibodies against specific post-translationally modified proteins are present in patients with lupus and associate with major neuropsychiatric manifestations

Background

Although autoantibodies are an important hallmark of systemic lupus erythematosus (SLE), most are not specific for SLE or any of its clinical manifestations. Autoantibodies against post-translationally modified (PTM) proteins have been studied extensively in rheumatoid arthritis and associate with disease progression. While PTMs have also been detected in patients with SLE, studies on anti-PTM antibodies remain scarce. We studied the presence of anti-PTM antibodies in SLE and neuropsychiatric SLE (NPSLE), a manifestation that lacks serological markers.

Methods

IgG antibody responses against six PTMs (malondialdehyde–acetaldehyde adducts (MAA), advanced glycation end-products (AGE), carbamylation (CarP), citrullination, acetylation and nitration) were tested using ELISA in sera of 349 patients with SLE (mean age 44±13 years; 87% female) and compared with 108 healthy controls. Levels and positivity were correlated with clinical features and SLE manifestations.

Results

Anti-MAA, anti-AGE and anti-CarP antibodies were more prevalent in SLE compared with controls (MAA: 29% vs 3%, AGE: 18% vs 4%, CarP: 14% vs 5%, all p≤0.0001). Anti-MAA and anti-AGE antibodies correlated with clinical manifestations and serological inflammatory markers. Patients with major NPSLE showed higher positivity of anti-MAA (39% vs 24%, p=0.01) and anti-CarP antibodies (20% vs 11%, p=0.04) than patients without major NPSLE. In addition, anti-PTM antibody levels correlated with brain volumes, an objective measure of nervous system involvement.

Conclusions

In our NPSLE cohort, a subset of patients with SLE have anti-PTM antibodies against MAA, AGE and CarP modified proteins. Interestingly, anti-MAA and anti-CarP were more prevalent in NPSLE, a manifestation for which no biomarkers exist.

Selective brain regional changes in lipid profile with human aging

Fatty acids are key components in the structural diversity of lipids and play a strategic role in the functional properties of lipids which determine the integrity of neuronal and glial cell membranes, the generation of lipid signaling mediators, and the chemical reactivity of acyl chains. The present study analyzes using gas chromatography the fatty acid profiles of 13 regions of the human central nervous system in healthy individuals ranging from 40 to 80 years old. The outcomes suggest the existence of general traits in fatty acid composition such as an average chain length of 18 carbon atoms, high monounsaturated fatty acid content, and predominance in polyunsaturated fatty acids of those of series n-6 over series n-3 which are shared by all brain regions regardless of age. Our results also show a general sustained and relatively well-preserved lipid profile throughout the adult lifespan in most studied regions (olive, upper vermis, substantia nigra, thalamus, hippocampus, putamen, caudate, occipital cortex, parietal cortex, entorhinal cortex, and frontal cortex) with minor changes that are region-dependent. In contrast, of particular relevance is the involvement of the inferior temporal cortex and cingulate cortex. It is proposed that during normal human brain aging, the lipid profile is resistant to changes with age in most human brain regions to ensure cell survival and function, but some particular regions involved in specific memory domains are greatly affected.

Multivariate Assessment of Lipoxidative Metabolites, Trace Biometals, and Antioxidant and Detoxifying Activities in the Cerebrospinal Fluid Define a Fingerprint of Preclinical Stages of Alzheimer’s Disease

Background: There exists considerable interest in the identification of molecular traits during early stages of Alzheimer’s disease (AD). Mild cognitive impairment (MCI) is considered the closest prodromal stage of AD, and to develop gradually from earlier stages although not always progresses to AD. Classical cerebrospinal fluid (CSF) AD biomarkers, amyloid-β peptides and tau/p-tau proteins, have been measured in prodromal stages yet results are heterogeneous and far from conclusive. Therefore, there exists a pressing need to identify a neurochemical signature for prodromal stages and to predict which cases might progress to AD. Objective: Exploring potential CSF biomarkers related to brain oxidative and inorganic biochemistry during prodromal stages of the disease. Methods: We have analyzed CSF levels of lipoxidative markers (MDA and 8-isoF2α), biometals (Cu, Zn, Se, Mn, and Fe), iron-transport protein transferrin (TFER), antioxidant enzymes (SOD and GPx4), detoxifying enzymes (GST and BuChE), as well as classical amyloid-β and total and phosphorylated tau, in cognitively healthy controls, patients with MCI, and subjects exhibiting subjective memory complaints (SMC). Results: Inter-group differences for several variables exhibit differentiable trends along the HC ⟶ SMC ⟶ MCI sequence. More interestingly, the combination of Se, Cu, Zn, SOD, TFER, and GST variables allow differentiable fingerprints for control subjects and each prodromal stage. Further, multivariate scores correlate positively with neurocognitive In-Out test, hence with both episodic memory decline and prediction to dementia. Conclusion: We conclude that changes in the CSF biochemistry related to brain oxidative defense and neurometallomics might provide more powerful and accurate diagnostic tools in preclinical stages of AD.

A Neuroscience Primer for Integrating Geroscience With the Neurobiology of Aging

Neuroscience has a rich history of studies focusing on neurobiology of aging. However, much of the aging studies in neuroscience occur outside of the gerosciences. The goal of this primer is 2-fold: first, to briefly highlight some of the history of aging neurobiology and second, to introduce to geroscientists the broad spectrum of methodological approaches neuroscientists use to study the neurobiology of aging. This primer is accompanied by a corresponding geroscience primer, as well as a perspective on the current challenges and triumphs of the current divide across these 2 fields. This series of manuscripts is intended to foster enhanced collaborations between neuroscientists and geroscientists with the intent of strengthening the field of cognitive aging through inclusion of parameters from both areas of expertise.

NLRP1 inflammasome involves in learning and memory impairments and neuronal damages during aging process in mice

Background

Brain aging is an important risk factor in many human diseases, such as Alzheimer’s disease (AD). The production of excess reactive oxygen species (ROS) mediated by nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2) and the maturation of inflammatory cytokines caused by activation of the NOD-like receptor protein 1 (NLRP1) inflammasome play central roles in promoting brain aging. However, it is still unclear when and how the neuroinflammation appears in the brain during aging process.

Methods

In this study, we observed the alterations of learning and memory impairments, neuronal damage, NLRP1 inflammasome activation, ROS production and NOX2 expression in the young 6-month-old (6 M) mice, presenile 16 M mice, and older 20 M and 24 M mice.

Results

The results indicated that, compared to 6 M mice, the locomotor activity, learning and memory abilities were slightly decreased in 16 M mice, and were significantly decreased in 20 M and 24 M mice, especially in the 24 M mice. The pathological results also showed that there were no significant neuronal damages in 6 M and 16 M mice, while there were obvious neuronal damages in 20 M and 24 M mice, especially in the 24 M group. Consistent with the behavioral and histological changes in the older mice, the activity of β-galactosidase (β-gal), the levels of ROS and IL-1β, and the expressions of NLRP1, ASC, caspase-1, NOX2, p47phox and p22phox were significantly increased in the cortex and hippocampus in the older 20 M and 24 M mice.

Conclusion

Our study suggested that NLRP1 inflammasome activation may be closely involved in aging-related neuronal damage and may be an important target for preventing brain aging.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12993-021-00185-x.

New insights into human prefrontal cortex aging with a lipidomics approach

INTRODUCTION

Human prefrontal cortex (hPFC) is a recent evolutionarily developed brain region involved in cognitive functions. Human cognitive functions decline during aging. Yet the molecular mechanisms underlying the functional deterioration of the neural cells of this brain region still remain to be fully described.

AREAS COVERED

In this review, we explore the role of lipids in hPFC aging. Firstly, we briefly consider the approaches used to identify lipid species in brain tissue with special attention paid to a lipidomics analysis. Then, as the evolution process has conferred a specific lipid profile on the hPFC, we consider the lipidome of hPFC. In addition, the role of lipids in hPFC aging, and in particular, the cognitive decline associated with aging, is discussed. Finally, nutritional and pharmacological interventions designed to modulate this process are examined. It is suggested that the dysfunction of key cellular processes secondarily to the damage of lipid membrane underlies the cognitive decline of hPFC during aging.

EXPERT OPINION

Lipidomics methods are and will continue to be key tools in the effort to gain additional insights into the aging of the human brain.

The Causal Role of Lipoxidative Damage in Mitochondrial Bioenergetic Dysfunction Linked to Alzheimer's Disease Pathology

Current shreds of evidence point to the entorhinal cortex (EC) as the origin of the Alzheimer’s disease (AD) pathology in the cerebrum. Compared with other cortical areas, the neurons from this brain region possess an inherent selective vulnerability derived from particular oxidative stress conditions that favor increased mitochondrial molecular damage with early bioenergetic involvement. This alteration of energy metabolism is the starting point for subsequent changes in a multitude of cell mechanisms, leading to neuronal dysfunction and, ultimately, cell death. These events are induced by changes that come with age, creating the substrate for the alteration of several neuronal pathways that will evolve toward neurodegeneration and, consequently, the development of AD pathology. In this context, the present review will focus on description of the biological mechanisms that confer vulnerability specifically to neurons of the entorhinal cortex, the changes induced by the aging process in this brain region, and the alterations at the mitochondrial level as the earliest mechanism for the development of AD pathology. Current findings allow us to propose the existence of an altered allostatic mechanism at the entorhinal cortex whose core is made up of mitochondrial oxidative stress, lipid metabolism, and energy production, and which, in a positive loop, evolves to neurodegeneration, laying the basis for the onset and progression of AD pathology.

The Advanced Lipoxidation End-Product Malondialdehyde-Lysine in Aging and Longevity

The nonenzymatic adduction of malondialdehyde (MDA) to the protein amino groups leads to the formation of malondialdehyde-lysine (MDALys). The degree of unsaturation of biological membranes and the intracellular oxidative conditions are the main factors that modulate MDALys formation. The low concentration of this modification in the different cellular components, found in a wide diversity of tissues and animal species, is indicative of the presence of a complex network of cellular protection mechanisms that avoid its cytotoxic effects. In this review, we will focus on the chemistry of this lipoxidation-derived protein modification, the specificity of MDALys formation in proteins, the methodology used for its detection and quantification, the MDA-lipoxidized proteome, the metabolism of MDA-modified proteins, and the detrimental effects of this protein modification. We also propose that MDALys is an indicator of the rate of aging based on findings which demonstrate that (i) MDALys accumulates in tissues with age, (ii) the lower the concentration of MDALys the greater the longevity of the animal species, and (iii) its concentration is attenuated by anti-aging nutritional and pharmacological interventions.

Type III intermediate filaments as targets and effectors of electrophiles and oxidants

Intermediate filaments (IFs) play key roles in cell mechanics, signaling and homeostasis. Their assembly and dynamics are finely regulated by posttranslational modifications. The type III IFs, vimentin, desmin, peripherin and glial fibrillary acidic protein (GFAP), are targets for diverse modifications by oxidants and electrophiles, for which their conserved cysteine residue emerges as a hot spot. Pathophysiological examples of these modifications include lipoxidation in cell senescence and rheumatoid arthritis, disulfide formation in cataracts and nitrosation in endothelial shear stress, although some oxidative modifications can also be detected under basal conditions. We previously proposed that cysteine residues of vimentin and GFAP act as sensors for oxidative and electrophilic stress, and as hinges influencing filament assembly. Accumulating evidence indicates that the structurally diverse cysteine modifications, either per se or in combination with other posttranslational modifications, elicit specific functional outcomes inducing distinct assemblies or network rearrangements, including filament stabilization, bundling or fragmentation. Cysteine-deficient mutants are protected from these alterations but show compromised cellular performance in network assembly and expansion, organelle positioning and aggresome formation, revealing the importance of this residue. Therefore, the high susceptibility to modification of the conserved cysteine of type III IFs and its cornerstone position in filament architecture sustains their role in redox sensing and integration of cellular responses. This has deep pathophysiological implications and supports the potential of this residue as a drug target.

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Type III intermediate filaments can be modified by many oxidants and electrophiles.

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Oxidative modifications of type III IFs occur in normal and pathological conditions.

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The conserved cysteine residue acts as a hub for redox/electrophilic modifications.

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Cysteine modifications elicit structure-dependent type III IF rearrangements.

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Type III intermediate filaments act as sensors for oxidative and electrophilic stress.

n-3 Polyunsaturated Fatty Acids and Their Derivates Reduce Neuroinflammation during Aging

: Aging is associated to cognitive decline, which can lead to loss of life quality, personal suffering, and ultimately neurodegenerative diseases. Neuroinflammation is one of the mechanisms explaining the loss of cognitive functions. Indeed, aging is associated to the activation of inflammatory signaling pathways, which can be targeted by specific nutrients with anti-inflammatory effects. Dietary n-3 polyunsaturated fatty acids (PUFAs) are particularly attractive as they are present in the brain, possess immunomodulatory properties, and are precursors of lipid derivates named specialized pro-resolving mediators (SPM). SPMs are crucially involved in the resolution of inflammation that is modified during aging, resulting in chronic inflammation. In this review, we first examine the effect of aging on neuroinflammation and then evaluate the potential beneficial effect of n-3 PUFA as precursors of bioactive derivates, particularly during aging, on the resolution of inflammation. Lastly, we highlight evidence supporting a role of n-3 PUFA during aging.

Electrophile Signaling and Emerging Immuno- and Neuro-modulatory Electrophilic Pharmaceuticals

With a lipid-rich environment and elevated oxygen consumption, the central nervous system (CNS) is subject to intricate regulation by lipid-derived electrophiles (LDEs). Investigations into oxidative damage and chronic LDE generation in neural disorders have spurred the development of tools that can detect and catalog the gamut of LDE-adducted proteins. Despite these advances, deconstructing the precise consequences of individual protein-specific LDE modifications remained largely impossible until recently. In this perspective, we first overview emerging toolsets that can decode electrophile-signaling events in a protein/context-specific manner, and how the accumulating mechanistic insights brought about by these tools have begun to offer new means to modulate pathways relevant to multiple sclerosis (MS). By surveying the latest data surrounding the blockbuster MS drug dimethyl fumarate that functions through LDE-signaling-like mechanisms, we further provide a vision for how chemical biology tools probing electrophile signaling may be leveraged toward novel interventions in CNS disease.

Redox lipidomics to better understand brain aging and function

Human prefrontal cortex (PFC) is a recently evolutionary emerged brain region involved in cognitive functions. Human cognitive abilities decline during aging. Yet the molecular mechanisms that sustain the preservation or deterioration of neurons and PFC functions are unknown. In this review, we focus on the role of lipids in human PFC aging. As the evolution of brain lipid concentrations is particularly accelerated in the human PFC, conferring a specific lipid profile, a brief approach to the lipidome of PFC was consider along with the relationship between lipids and lipoxidative damage, and the role of lipids in human PFC aging. In addition, the specific targets of lipoxidative damage in human PFC, the affected biological processes, and their potential role in the cognitive decline associated with aging are discussed. Finally, interventions designed to modify this process are considered. We propose that the dysfunction of key biological processes due to selective protein lipoxidation damage may have a role the cognitive decline of PFC during aging.

COX-2/sEH dual inhibitor PTUPB alleviates bleomycin-induced pulmonary fibrosis in mice via inhibiting senescence

Pulmonary fibrosis (PF) is a senescence-associated disease with poor prognosis. Currently, there is no effective therapeutic strategy for preventing and treating the disease process. Mounting evidence suggests that arachidonic acid (ARA) metabolites are involved in the pathogenesis of various fibrosis. However, the relationship between the metabolism of ARA and PF is still elusive. In this study, we observed a disorder in the cyclooxygenase-2/cytochrome P450 (COX-2/CYP) metabolism of ARA in the lungs of PF mice induced by bleomycin (BLM). Therefore, we aimed to explore the role of COX-2/CYP-derived ARA metabolic disorders in PF. PTUPB, a dual COX-2 and soluble epoxide hydrolase (sEH) inhibitor, was used to restore the balance of COX-2/CYP metabolism. sEH is an enzyme hydrolyzing epoxyeicosatrienoic acids derived from ARA by CYP. We found that PTUPB alleviated the pathological changes in lung tissue and collagen deposition, as well as reduced senescence marker molecules (p16^Ink4a and p53-p21^Waf1/Cip1 ) in the lungs of mice treated by BLM. In vitro, we found that PTUPB pretreatment remarkably reduced the expression of senescence-related molecules in the alveolar epithelial cells (AECs) induced by BLM. In conclusion, our study supports the notion that the COX-2/CYP-derived ARA metabolic disorders may be a potential therapeutic target for PF via inhibiting the cellular senescence in AECs.

Can krill oil be of use for counteracting neuroinflammatory processes induced by high fat diet and aging?

Most neurodegenerative diseases, such as Alzheimer's and Parkinson's disease, demonstrate preceding or on-going inflammatory processes. Therefore, discovering effective means of counteracting detrimental inflammatory mediators in the brain could help alter aging-related disease onset and progression. Fish oil and marine-derived omega-3, long-chain polyunsaturated fatty acids (LC n-3) have shown promising anti-inflammatory effects both systemically and centrally. More specifically, krill oil (KO), extracted from small Antarctic crustaceans, is an alternative type of LC n-3 with reported health benefits including improvement of spatial memory and learning, memory loss, systemic inflammation and depression symptoms. Similar to the more widely studied fish oil, KO contains the long chain fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) which are essential for basic brain functions. Moreover, the phospholipid bound nature of fatty acids found in KO improves bioavailability and efficiency of absorption, thus supporting the belief that KO may offer a superior method of dietary n-3 delivery. Finally, KO contains astaxanthin, an antioxidant capable of reducing potentially excessive oxidative stress and inflammation within the brain. This review will discuss the potential benefits of KO over other marine-based LC n-3 on brain inflammation and cognitive function in the context of high fat diets and aging.

Oxidative Stress and Advanced Lipoxidation and Glycation End Products (ALEs and AGEs) in Aging and Age-Related Diseases

Oxidative stress is a consequence of the use of oxygen in aerobic respiration by living organisms and is denoted as a persistent condition of an imbalance between the generation of reactive oxygen species (ROS) and the ability of the endogenous antioxidant system (AOS) to detoxify them. The oxidative stress theory has been confirmed in many animal studies, which demonstrated that the maintenance of cellular homeostasis and biomolecular stability and integrity is crucial for cellular longevity and successful aging. Mitochondrial dysfunction, impaired protein homeostasis (proteostasis) network, alteration in the activities of transcription factors such as Nrf2 and NF-κB, and disturbances in the protein quality control machinery that includes molecular chaperones, ubiquitin-proteasome system (UPS), and autophagy/lysosome pathway have been observed during aging and age-related chronic diseases. The accumulation of ROS under oxidative stress conditions results in the induction of lipid peroxidation and glycoxidation reactions, which leads to the elevated endogenous production of reactive aldehydes and their derivatives such as glyoxal, methylglyoxal (MG), malonic dialdehyde (MDA), and 4-hydroxy-2-nonenal (HNE) giving rise to advanced lipoxidation and glycation end products (ALEs and AGEs, respectively). Both ALEs and AGEs play key roles in cellular response to oxidative stress stimuli through the regulation of a variety of cell signaling pathways. However, elevated ALE and AGE production leads to protein cross-linking and aggregation resulting in an alteration in cell signaling and functioning which causes cell damage and death. This is implicated in aging and various age-related chronic pathologies such as inflammation, neurodegenerative diseases, atherosclerosis, and vascular complications of diabetes mellitus. In the present review, we discuss experimental data evidencing the impairment in cellular functions caused by AGE/ALE accumulation under oxidative stress conditions. We focused on the implications of ALEs/AGEs in aging and age-related diseases to demonstrate that the identification of cellular dysfunctions involved in disease initiation and progression can serve as a basis for the discovery of relevant therapeutic agents.

Lipids and lipoxidation in human brain aging. Mitochondrial ATP-synthase as a key lipoxidation target

The human brain is a target of the aging process like other cell systems of the human body. Specific regions of the human brain exhibit differential vulnerabilities to the aging process. Yet the underlying mechanisms that sustain the preservation or deterioration of neurons and cerebral functions are unknown. In this review, we focus attention on the role of lipids and the importance of the cross-regionally different vulnerabilities in human brain aging. In particular, we first consider a brief approach to the lipidomics of human brain, the relationship between lipids and lipoxidative damage, the role of lipids in human brain aging, and the specific targets of lipoxidative damage in human brain and during aging. It is proposed that the restricted set of modified proteins and the functional categories involved may be considered putative collaborative factors contributing to neuronal aging, and that mitochondrial ATP synthase is a key lipoxidative target in human brain aging.