Oxidative Stress, Neuroinflammation, and NADPH Oxidase: Implications in the Pathogenesis and Treatment of Alzheimer's Disease

NADPH oxidase 4 (NOX4) as a biomarker and therapeutic target in neurodegenerative diseases

Diseases like Alzheimer's and Parkinson's diseases are defined by inflammation and the damage neurons undergo due to oxidative stress. A primary reactive oxygen species contributor in the central nervous system, NADPH oxidase 4, is viewed as a potential therapeutic touchstone and indicative marker for these ailments. This in-depth review brings to light distinct features of NADPH oxidase 4, responsible for generating superoxide and hydrogen peroxide, emphasizing its pivotal role in activating glial cells, inciting inflammation, and disturbing neuronal functions. Significantly, malfunctioning astrocytes, forming the majority in the central nervous system, play a part in advancing neurodegenerative diseases, due to their reactive oxygen species and inflammatory factor secretion. Our study reveals that aiming at NADPH oxidase 4 within astrocytes could be a viable treatment pathway to reduce oxidative damage and halt neurodegenerative processes. Adjusting NADPH oxidase 4 activity might influence the neuroinflammatory cytokine levels, including myeloperoxidase and osteopontin, offering better prospects for conditions like Alzheimer's disease and Parkinson's disease. This review sheds light on the role of NADPH oxidase 4 in neural degeneration, emphasizing its drug target potential, and paving the path for novel treatment approaches to combat these severe conditions.

Oligomeric Tau-induced oxidative damage and functional alterations in cerebral endothelial cells: Role of RhoA/ROCK signaling pathway

Despite of yet unknown mechanism, microvascular deposition of oligomeric Tau (oTau) has been implicated in alteration of the Blood-Brain Barrier (BBB) function in Alzheimer's disease (AD) brains. In this study, we employed an in vitro BBB model using primary mouse cerebral endothelial cells (CECs) to investigate the mechanism underlying the effects of oTau on BBB function. We found that exposing CECs to oTau induced oxidative stress through NADPH oxidase, increased oxidative damage to proteins, decreased proteasome activity, and expressions of tight junction (TJ) proteins including occludin, zonula occludens-1 (ZO-1) and claudin-5. These effects were suppressed by the pretreatment with Fasudil, a RhoA/ROCK signaling inhibitor. Consistent with the biochemical alterations, we found that exposing the basolateral side of CECs to oTau in the BBB model disrupted the integrity of the BBB, as indicated by an increase in FITC-dextran transport across the model, and a decrease in trans endothelial electrical resistance (TEER). oTau also increased the transmigration of peripheral blood mononuclear cells (PBMCs) in the BBB model. These functional alterations in the BBB induced by oTau were also suppressed by Fasudil. Taken together, our findings suggest that targeting the RhoA/ROCK pathway can be a potential therapeutic strategy to maintain BBB function in AD.

Insulin resistance as the molecular link between diabetes and Alzheimer's disease

Diabetes mellitus (DM) and Alzheimer's disease (AD) are two major health concerns that have seen a rising prevalence worldwide. Recent studies have indicated a possible link between DM and an increased risk of developing AD. Insulin, while primarily known for its role in regulating blood sugar, also plays a vital role in protecting brain functions. Insulin resistance (IR), especially prevalent in type 2 diabetes, is believed to play a significant role in AD's development. When insulin signalling becomes dysfunctional, it can negatively affect various brain functions, making individuals more susceptible to AD's defining features, such as the buildup of beta-amyloid plaques and tau protein tangles. Emerging research suggests that addressing insulin-related issues might help reduce or even reverse the brain changes linked to AD. This review aims to explore the rela-tionship between DM and AD, with a focus on the role of IR. It also explores the molecular mechanisms by which IR might lead to brain changes and assesses current treatments that target IR. Understanding IR's role in the connection between DM and AD offers new possibilities for treatments and highlights the importance of continued research in this interdisciplinary field.

Genomic stress and impaired DNA repair in Alzheimer disease

Alzheimer disease (AD) is the most prominent form of dementia and has received considerable attention due to its growing burden on economic, healthcare and basic societal infrastructures. The two major neuropathological hallmarks of AD, i.e., extracellular amyloid beta (Aβ) peptide plaques and intracellular hyperphosphorylated Tau neurofibrillary tangles, have been the focus of much research, with an eye on understanding underlying disease mechanisms and identifying novel therapeutic avenues. One often overlooked aspect of AD is how Aβ and Tau may, through indirect and direct mechanisms, affect genome integrity. Herein, we review evidence that Aβ and Tau abnormalities induce excessive genomic stress and impair genome maintenance mechanisms, events that can promote DNA damage-induced neuronal cell loss and associated brain atrophy.

Effectiveness and mechanisms of combined use of antioxidant nutrients in protecting against oxidative stress-induced neuronal loss and related neurological deficits

BACKGROUND

Oxidative stress is a well-known pathological factor driving neuronal loss and age-related neurodegenerative diseases. Melatonin, coenzyme Q10 and lecithin are three common nutrients with an antioxidative capacity. Here, we examined the effectiveness of them administrated individually and in combination in protecting against oxidative stress-induced neuronal death in vitro, and neurodegenerative conditions such as Alzheimer's disease and associated deficits in vivo.

METHODS

Mouse neuroblastoma Neuro-2a (N2a) cells were exposed with H2O2 for 6 h, and subsequently treated with melatonin, coenzyme Q10, and lecithin alone or in combination for further 24 h. Cell viability was assessed using the CCK-8 assay. Eight-week-old male mice were intraperitoneally injected with D-(+)-galactose for 10 weeks and administrated with melatonin, coenzyme Q10, lecithin, or in combination for 5 weeks starting from the sixth week, followed by behavioral tests to assess the effectiveness in mitigating neurological deficits, and biochemical assays to explore the underlying mechanisms.

RESULTS

Exposure to H2O2 significantly reduced the viability of N2a cells and increased oxidative stress and tau phosphorylation, all of which were alleviated by treatment with melatonin, coenzyme Q10, lecithin alone, and, most noticeably, by combined treatment. Administration of mice with D-(+)-galactose-induced oxidative stress and tau phosphorylation, brain aging, impairments in learning and memory, anxiety- and depression-like behaviors, and such detrimental effects were mitigated by melatonin, coenzyme Q10, lecithin alone, and, most consistently, by combined treatment.

CONCLUSIONS

These results suggest that targeting oxidative stress via supplementation of antioxidant nutrients, particularly in combination, is a better strategy to alleviate oxidative stress-mediated neuronal loss and brain dysfunction due to age-related neurodegenerative conditions.

Beneficial effect of lupeol and metformin in mouse model of intracerebroventricular streptozotocin induced dementia

This study examines the effectiveness of lupeol and metformin in a mouse model of dementia generated by intracerebroventricular streptozotocin (i.c.v., STZ). Dementia was induced in Swiss mice with the i.c.v. administration of STZ at a dosage of 3 mg/kg on the first and third day. The assessment of dementia involved an examination of the Morris Water Maze (MWM) performance, as well as a number of biochemical and histological studies. STZ treatment resulted in significant decrease in MWM performance; various biochemical alterations (increase in brain acetyl cholinesterase (AChE) activity, thiobarbituric acid reactive species (TBARS), nitrite/nitrate, and reduction in nuclear factor erythroid 2 related factor-2 (Nrf-2), reduced glutathione (GSH) levels) and neuroinflammation [increased myeloperoxidase (MPO) activity & neutrophil infiltration]. The administration of Lupeol (50 mg/kg & 100 mg/kg; p.o.) and Metformin (150 mg/kg & 300 mg/kg; p.o.) demonstrated a considerable reduction in the behavioral, biochemical, and histological alterations produced by STZ. Low dose combination of lupeol (50 mg/kg; p.o.) and Metformin (150 mg/kg; p.o.) produced more pronounced effect than that of high doses of either agent alone. It is concluded that Lupeol and Metformin has shown efficacy in dementia with possible synergism between the two and can be explored as potential therapeutic agents for managing dementia of Alzheimer's disease (AD) type.

Inositol Hexaphosphate as an Inhibitor and Potential Regulator of p47phox Membrane Anchoring

As a key component for NADPH oxidase 2 (NOX2) activation, the peripheral membrane protein p47phox translocates a cytosolic activating complex to the membrane through its PX domain. This study elucidates a potential regulatory mechanism of p47phox recruitment and NOX2 activation by inositol hexaphosphate (IP6). Through NMR, fluorescence polarization, and FRET experimental results, IP6 is shown to be capable of breaking the lipid binding and membrane anchoring events of p47phox-PX with low micromolar potency. Other phosphorylated inositol species such as IP5(1,3,4,5,6), IP4(1,3,4,5), and IP3(1,3,4) show weaker binding and no ability to inhibit lipid interactions in physiological concentration ranges. The low micromolar potency of IP6 inhibition of the p47phox membrane anchoring suggests that physiologically relevant concentrations of IP6 serve as regulators, as seen in other membrane anchoring domains. The PX domain of p47phox is known to be promiscuous to a variety of phosphatidylinositol phosphate (PIP) lipids, and this regulation may help target the domain only to the membranes most highly enriched with the highest affinity PIPs, such as the phagosomal membrane, while preventing aberrant binding to other membranes with high and heterogeneous PIP content, such as the plasma membrane. This study provides insight into a potential novel regulatory mechanism behind NOX2 activation and reveals a role for small-molecule regulation in this important NOX2 activator.

Tanshinone IIA improves Alzheimer's disease via RNA nuclear-enriched abundant transcript 1/microRNA-291a-3p/member RAS oncogene family Rab22a axis

BACKGROUND

Alzheimer's disease (AD) is a neurodegenerative condition characterized by oxidative stress and neuroinflammation. Tanshinone IIA (Tan-IIA), a bioactive compound isolated from Salvia miltiorrhiza plants, has shown potential neuroprotective effects; however, the mechanisms underlying such a function remain unclear.

AIM

To investigate potential Tan-IIA neuroprotective effects in AD and to elucidate their underlying mechanisms.

METHODS

Hematoxylin and eosin staining was utilized to analyze structural brain tissue morphology. To assess changes in oxidative stress and neuroinflammation, we performed enzyme-linked immunosorbent assay and western blotting. Additionally, the effect of Tan-IIA on AD cell models was evaluated in vitro using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Genetic changes related to the long non-coding RNA (lncRNA) nuclear-enriched abundant transcript 1 (NEAT1)/microRNA (miRNA, miR)-291a-3p/member RAS oncogene family Rab22a axis were assessed through reverse transcription quantitative polymerase chain reaction.

RESULTS

In vivo, Tan-IIA treatment improved neuronal morphology and attenuated oxidative stress and neuroinflammation in the brain tissue of AD mice. In vitro experiments showed that Tan-IIA dose-dependently ameliorated the amyloid-beta 1-42-induced reduction of neural stem cell viability, apoptosis, oxidative stress, and neuroinflammation. In this process, the lncRNA NEAT1 - a potential therapeutic target - is highly expressed in AD mice and downregulated via Tan-IIA treatment. Mechanistically, NEAT1 promotes the transcription and translation of Rab22a via miR-291a-3p, which activates nuclear factor kappa-B (NF-κB) signaling, leading to activation of the pro-apoptotic B-cell lymphoma 2-associated X protein and inhibition of the anti-apoptotic B-cell lymphoma 2 protein, which exacerbates AD. Tan-IIA intervention effectively blocked this process by inhibiting the NEAT1/miR-291a-3p/Rab22a axis and NF-κB signaling.

CONCLUSION

This study demonstrates that Tan-IIA exerts neuroprotective effects in AD by modulating the NEAT1/miR-291a-3p/Rab22a/NF-κB signaling pathway, serving as a foundation for the development of innovative approaches for AD therapy.

Pathways linking microbiota-gut-brain axis with neuroinflammatory mechanisms in Alzheimer's pathophysiology

Disturbances in the local and peripheral immune systems are closely linked to a wide range of diseases. In the context of neurodegenerative disorders such as Alzheimer's disease (AD), inflammation plays a crucial role, often appearing as a common manifestation despite the variability in the occurrence of other pathophysiological hallmarks. Thus, combating neuroinflammation holds promise in treating complex pathophysiological diseases like AD. Growing evidence suggests the gut microbiome's crucial role in shaping the pathogenesis of AD by influencing inflammatory mediators. Gut dysbiosis can potentially activate neuroinflammatory pathways through bidirectional signaling of the gut-brain axis; however, the precise mechanisms of this complex interweaved network remain largely unclear. In these milieus, this review attempts to summarize the contributing role of gut microbiome-mediated neuroinflammatory signals in AD pathophysiology, while also pondering potential mechanisms through which commensal and pathogenic gut microbes affect neuroinflammation. While certain taxa such as Roseburia and Escherichia have been strongly correlated with AD, other clades such as Bacteroides and Faecalibacterium exhibit variations at the species and strain levels. In order to disentangle the inflammatory aspects of neurodegeneration attributed to the gut microbiome, it is imperative that future mechanistic studies investigate the species/strain-level dependency of commensals, opportunistic, and pathogenic gut microbes that consistently show correlations with AD patients across multiple associative studies.

Hyperbaric oxygen improves cerebral ischemia-reperfusion injury in rats via inhibition of ferroptosis

BACKGROUND

Our previous study found that hyperbaric oxygen (HBO) attenuated cognitive impairment in mice induced by cerebral ischemia-reperfusion injury (CIRI). However, its mechanism of action is not fully understood. In this study, we aimed to establish a rat model of cerebral ischemia-reperfusion, explore the possible role of ferroptosis in the pathogenesis of CIRI, and observe the effect of HBO on ferroptosis-mediated CIRI.

METHODS

Sprague Dawley (SD) rats were randomly divided into control, model, Ferrostatin-1 (Fer-1), HBO and Fer-1+ HBO groups. Morris water maze, myelin basic protein (MBP) and β-tubulin immunoreactivity were assessed to evaluate the neuroprotective effects of HBO on cerebral ischemia reperfusion injury. Ferroptosis were examined to investigate the mechanism underlying the effects of HBO.

RESULTS

Our result showed that Fer-1 and HBO improved learning and memory ability in the navigation trail and probe trail of the Morris water maze and increased MBP and β-tubulin immunoreactivity of the cortex in the model rats. The levels of ferritin, malondialdehyde (MDA) and glutathione (GSH) in the serum were also reversed by Fer-1 and HBO treatment. Mitochondrial cristae dissolution and vacuolization were observed in the model group by transmission electron microscopy and these conditions were improved in the Fer-1 and HBO groups. Furthermore, Fer-1 and HBO treatment reversed Prostaglandin-Endoperoxide Synthase 2 (PTGS2), Iron Responsive Element Binding Protein 2 (IREB2), acyl-CoA synthetase long chain family member 4 (ACSL4) and Solute Carrier Family 7 Member 11 (SLC7A11) mRNA levels and Transferrin Receptor 1 (TFR1), ferritin light chain (FTL), ferritin heavy chain 1 (FTH1), glutathione peroxidase 4 (GPX4), Nuclear factor E2-related factor 2 (Nrf2), lysophosphatidylcholine acyltransferase 3 (LPCAT3), c-Jun N-terminal kinase (JNK), phosphorylated c-Jun N-terminal kinase (P-JNK) phosphorylated Extracellular signal-regulated protein kinase (P-ERK) and mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK) protein levels. The above changes were more pronounced in Fer-1+ HBOGroup.

DISCUSSION

The results of the present study indicated that HBO improves cerebral ischemia-reperfusion injury in rats, which may be related to inhibition of ferroptosis. This also means that ferroptosis may become a new target of HBO against CIRI.

Oxygen metabolism abnormality and Alzheimer's disease: An update

Oxygen metabolism abnormality plays a crucial role in the pathogenesis of Alzheimer's disease (AD) via several mechanisms, including hypoxia, oxidative stress, and mitochondrial dysfunction. Hypoxia condition usually results from living in a high-altitude habitat, cardiovascular and cerebrovascular diseases, and chronic obstructive sleep apnea. Chronic hypoxia has been identified as a significant risk factor for AD, showing an aggravation of various pathological components of AD, such as amyloid β-protein (Aβ) metabolism, tau phosphorylation, mitochondrial dysfunction, and neuroinflammation. It is known that hypoxia and excessive hyperoxia can both result in oxidative stress and mitochondrial dysfunction. Oxidative stress and mitochondrial dysfunction can increase Aβ and tau phosphorylation, and Aβ and tau proteins can lead to redox imbalance, thus forming a vicious cycle and exacerbating AD pathology. Hyperbaric oxygen therapy (HBOT) is a non-invasive intervention known for its capacity to significantly enhance cerebral oxygenation levels, which can significantly attenuate Aβ aggregation, tau phosphorylation, and neuroinflammation. However, further investigation is imperative to determine the optimal oxygen pressure, duration of exposure, and frequency of HBOT sessions. In this review, we explore the prospects of oxygen metabolism in AD, with the aim of enhancing our understanding of the underlying molecular mechanisms in AD. Current research aimed at attenuating abnormalities in oxygen metabolism holds promise for providing novel therapeutic approaches for AD.

The effect of chronic intermittent hypobaric hypoxia improving liver damage in metabolic syndrome rats through ferritinophagy

Studies have confirmed that hepatic iron overload is one of the important factors causing liver damage in the metabolic syndrome (MS). As a special form of autophagy, ferritinophagy is involved in the regulation of iron metabolism. Our previous studies have shown that chronic intermittent hypobaric hypoxia (CIHH) can improve the iron metabolism disorder. The aim of this study was to investigate how CIHH improves liver damage through ferritinophagy in MS rats. Male Sprague-Dawley rats aged 8-10 weeks were randomly divided into four groups: control (CON), CIHH (exposed to hypoxia at a simulated altitude of 5000 m for 28 days, 6 h daily), MS model (induced by a 16-week high-fat diet and 10% fructose water feeding), and MS + CIHH (exposed to CIHH after a 16-week MS inducement) groups. Liver index, liver function, iron content, tissue morphology, oxidative stress, ferritinophagy, ferroptosis, and iron metabolism-related protein expression were measured, and the ferritinophagy flux in the liver was further analyzed. Compared with CON rats, MS rats had an increased liver index, damaged liver tissue and function, increased iron content and iron deposition, disrupted iron metabolism, significantly increased oxidative stress indicators in the liver, significantly upregulated expression of ferroptosis-related proteins, and downregulated expression of nuclear receptor coactivator 4 (NCOA4) and ferritinophagy flux. After CIHH treatment, the degree of liver damage and various abnormal indicators in MS rats were significantly improved. CIHH may improve liver damage by promoting NCOA4-mediated ferritinophagy, reducing iron overload and oxidative stress, and thereby alleviating ferroptosis in MS rats.

Antioxidant and anti-Alzheimer activities of Clivia miniata (Lindl) roots, bulbs, and aerial parts: In-vitro and in-silico studies

Clivia miniata (Lindl) is a member of the family Amaryllidaceae known for its chemically diverse alkaloids with a wide range of biological activities. Many reports revealed a direct role of oxidative stress in the early stage of Alzheimer's disease (AD). Meanwhile, β-site amyloid precursor protein cleavage enzyme 1 (BACE-1) is a molecular target for the treatment of AD. We aimed to investigate C. miniata root, bulb, and aerial part chemical profiling, antioxidant, BACE-1, and AChE enzyme inhibitory activities. Results showed that the total root had the most potent radical scavenging activity as compared to the total bulb and aerial part, respectively. Ethanol root extract had the most potent BACE-1 inhibitory activity (IC50 = 0.02 ± 0.001 µg/mL) as compared to the bulb and aerial part (IC50 = 0.93 ± 0.13, 1.80 ± 0.24 µg/mL), respectively. Moreover, the total root extract mitigated AChE enzyme activity more than total bulb and aerial fractions with IC50 values of (0.06 ± 0.02, 0.58 ± 0.3, and 1.89 ± 0.42 µg/mL, respectively. Bioassay-guided acid-base fractionation confirmed superior BACE-1 inhibitory activity of the root fractions particularly, methylene chloride and ethyl acetate fractions with (IC50 values of 0.21 ± 0.60 and 0.01 ± 0.001 µg/mL), respectively. UPLC-MS analysis of ethyl acetate and methylene chloride fractions of C. miniata root led to the identification of eight phenolics and thirteen alkaloids, respectively. Molecular docking studies against BACE-1 protein revealed that lycorine di-hexoside, miniatine, and cliviaaline were the most promising hits. Further investigation of anti-AD potential of the aforementioned small molecules is required.

Optogenetics in Alzheimer's Disease: Focus on Astrocytes

Alzheimer's disease (AD) is the most common form of dementia, resulting in disability and mortality. The global incidence of AD is consistently surging. Although numerous therapeutic agents with promising potential have been developed, none have successfully treated AD to date. Consequently, the pursuit of novel methodologies to address neurodegenerative processes in AD remains a paramount endeavor. A particularly promising avenue in this search is optogenetics, enabling the manipulation of neuronal activity. In recent years, research attention has pivoted from neurons to glial cells. This review aims to consider the potential of the optogenetic correction of astrocyte metabolism as a promising strategy for correcting AD-related disorders. The initial segment of the review centers on the role of astrocytes in the genesis of neurodegeneration. Astrocytes have been implicated in several pathological processes associated with AD, encompassing the clearance of β-amyloid, neuroinflammation, excitotoxicity, oxidative stress, and lipid metabolism (along with a critical role in apolipoprotein E function). The effect of astrocyte-neuronal interactions will also be scrutinized. Furthermore, the review delves into a number of studies indicating that changes in cellular calcium (Ca2+) signaling are one of the causes of neurodegeneration. The review's latter section presents insights into the application of various optogenetic tools to manipulate astrocytic function as a means to counteract neurodegenerative changes.

Targeting lncRNA NEAT1 Hampers Alzheimer's Disease Progression

Long noncoding RNA nuclear enriched abundant transcript 1 (lnc-NEAT1) is closely implicated in neurological diseases, while its implication in Alzheimer's disease (AD) is rarely reported. This study aimed to investigate the effect of lnc-NEAT1 knockdown on neuron injury, inflammation, and oxidative stress in AD, as well as its interaction with downstream targets and pathways. APPswe/PS1dE9 transgenic mice were injected with negative control or lnc-NEAT1 interference lentivirus. Besides, AD cellular model was constructed by amyloid β treatment in mice primary neuron cells; then, knockdown of lnc-NEAT1 and microRNA-193a was performed alone or in combination. In vivo experiments revealed that Lnc-NEAT1 knockdown improved cognition in AD mice reflected by Morrison water maze and Y-maze assays. Besides, lnc-NEAT1 knockdown reduced injury and apoptosis, decreased inflammatory cytokine levels, repressed oxidative stress level, and activated adenosine cyclophosphate response element-binding protein (CREB)/brain-derived neurotrophic factor (BDNF) and nuclear factor erythroid 2-related factor 2 (NRF2)/nicotinamide adenine dinucleotide phosphate dehydrogenase 1 (NQO1) pathways in hippocampi of AD mice. Notably, lnc-NEAT1 down-regulated microRNA-193a both in vitro and in vivo and acted as a decoy of microRNA-193a. In vitro experiments showed that lnc-NEAT1 knockdown decreased apoptosis and oxidative stress, improved cell viability, also activated CREB/BDNF and NRF2/NQO1 pathways in AD cellular model. Meanwhile, microRNA-193a knockdown showed the opposite effects, which also attenuated lnc-NEAT1 knockdown-mediated reduction in injury, oxidative stress, and CREB/BDNF and NRF2/NQO1 pathways of AD cellular model. In conclusion, lnc-NEAT1 knockdown reduces neuron injury, inflammation, and oxidative stress through activating microRNA-193a mediated CREB/BDNF and NRF2/NQO1 pathways in AD.

Isoamericanin A improves lipopolysaccharide-induced memory impairment in mice through suppression of the nicotinamide adenine dinucleotide phosphateoxidase-dependent nuclear factor kappa B signaling pathway

Alzheimer's disease (AD) is the most frequent cause of dementia in the elderly. Isoamericanin A (ISOA) is a natural lignan possessing great potential for AD treatment. This study investigated the efficacy of ISOA on memory impairments in the mice intrahippocampal injected with lipopolysaccharide (LPS) and the underlying mechanism. Y-maze and Morris Water Maze data suggested that ISOA (5 and 10 mg/kg) ameliorated short- and long-term memory impairments, and attenuated neuronal loss and lactate dehydrogenase activity. ISOA exerted anti-inflammatory effect demonstrating by the reduction of ionized calcium-binding adapter molecule 1 positive cells and suppression of marker protein and pro-inflammation cytokines expressions induced by LPS. ISOA suppressed the nuclear factor kappa B (NF-κB) signaling pathway by inhibiting IκBα phosphorylation and NF-κB p65 phosphorylation and nuclear translocation. ISOA inhibited superoxide and intracellular reactive oxygen species accumulation by reducing nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation, demonstrating by suppressing NADP+ and NADPH contents, gp91phox expression, and p47phox expression and membrane translocation. These effects were enhanced in combination with NADPH oxidase inhibitor apocynin. The neuroprotective effect of ISOA was further proved in the in vitro models. Overall, our data revealed a novel pharmacological activity of ISOA: ameliorating memory impairment in AD via inhibiting neuroinflammation.

Inhibition of Enzymes Involved in Neurodegenerative Disorders and Aβ1-40 Aggregation by Citrus limon Peel Polyphenol Extract

Alzheimer's (AD) and Parkinson's diseases (PD) are multifactorial neurogenerative disorders of the Central Nervous System causing severe cognitive and motor deficits in elderly people. Because treatment of AD and PD by synthetic drugs alleviates the symptoms often inducing side effects, many studies have aimed to find neuroprotective properties of diet polyphenols, compounds known to act on different cell signaling pathways. In this article, we analyzed the effect of polyphenols obtained from the agro-food industry waste of Citrus limon peel (LPE) on key enzymes of cholinergic and aminergic neurotransmission, such as butyryl cholinesterase (BuChE) and monoamine oxidases (MAO)-A/B, on Aβ1-40 aggregation and on superoxide dismutase (SOD) 1/2 that affect oxidative stress. In our in vitro assays, LPE acts as an enzyme inhibitor on BuChE (IC50 ~ 73 µM), MAO-A/B (IC50 ~ 80 µM), SOD 1/2 (IC50 ~ 10-20 µM) and interferes with Aβ1-40 peptide aggregation (IC50 ~ 170 µM). These results demonstrate that LPE behaves as a multitargeting agent against key factors of AD and PD by inhibiting to various extents BuChE, MAOs, and SODs and reducing Aβ-fibril aggregation. Therefore, LPE is a promising candidate for the prevention and management of AD and PD symptoms in combination with pharmacological therapies.

The Promise of Niacin in Neurology

Niacin (vitamin B3) is an essential nutrient that treats pellagra, and prior to the advent of statins, niacin was commonly used to counter dyslipidemia. Recent evidence has posited niacin as a promising therapeutic for several neurological disorders. In this review, we discuss the biochemistry of niacin, including its homeostatic roles in NAD+ supplementation and metabolism. Niacin also has roles outside of metabolism, largely through engaging hydroxycarboxylic acid receptor 2 (Hcar2). These receptor-mediated activities of niacin include regulation of immune responses, phagocytosis of myelin debris after demyelination or of amyloid beta in models of Alzheimer's disease, and cholesterol efflux from cells. We describe the neurological disorders in which niacin has been investigated or has been proposed as a candidate medication. These are multiple sclerosis, Alzheimer's disease, Parkinson's disease, glioblastoma and amyotrophic lateral sclerosis. Finally, we explore the proposed mechanisms through which niacin may ameliorate neuropathology. While several questions remain, the prospect of niacin as a therapeutic to alleviate neurological impairment is promising.

Minocycline effects on memory and learning impairment in the beta-amyloid-induced Alzheimer's disease model in male rats using behavioral, biochemical, and histological methods

Alzheimer's disease (AD), as an advanced neurodegenerative disease, is characterized by the everlasting impairment of memory, which is determined by hyperphosphorylation of intracellular Tau protein and accumulation of beta-amyloid (Aβ) in the extracellular space. Minocycline is an antioxidant with neuroprotective effects that can freely cross the blood-brain barrier (BBB). This study investigated the effect of minocycline on the changes in learning and memory functions, activities of blood serum antioxidant enzymes, neuronal loss, and the number of Aβ plaques after AD induced by Aβ in male rats. Healthy adult male Wistar rats (200-220g) were divided randomly into 11 groups (n = 10). The rats received minocycline (50 and 100 mg/kg/day; per os (P.O.)) before, after, and before/after AD induction for 30 days. At the end of the treatment course, behavioral performance was measured by standardized behavioral paradigms. Subsequently, brain samples and blood serum were collected for histological and biochemical analysis. The results indicated that Aβ injection impaired learning and memory performances in the Morris water maze test, reduced exploratory/locomotor activities in the open field test, and enhanced anxiety-like behavior in the elevated plus maze. The behavioral deficits were accompanied by hippocampal oxidative stress (decreased glutathione (GSH) peroxidase enzyme activity and increased malondialdehyde (MDA) levels in the brain (hippocampus) tissue), increased number of Aβ plaques, and neuronal loss in the hippocampus evidenced by Thioflavin S and H&E staining, respectively. Minocycline improved anxiety-like behavior, recovered Aβ-induced learning and memory deficits, increased GSH and decreased MDA levels, and prevented neuronal loss and the accumulation of Aβ plaques. Our results demonstrated that minocycline has neuroprotective effects and can reduce memory dysfunction, which are due to its antioxidant and anti-apoptotic effects.

The role of Smo-Shh/Gli signaling activation in the prevention of neurological and ageing disorders

Sonic hedgehog (Shh) signaling is an essential central nervous system (CNS) pathway involved during embryonic development and later life stages. Further, it regulates cell division, cellular differentiation, and neuronal integrity. During CNS development, Smo-Shh signaling is significant in the proliferation of neuronal cells such as oligodendrocytes and glial cells. The initiation of the downstream signalling cascade through the 7-transmembrane protein Smoothened (Smo) promotes neuroprotection and restoration during neurological disorders. The dysregulation of Smo-Shh is linked to the proteolytic cleavage of GLI (glioma-associated homolog) into GLI3 (repressor), which suppresses target gene expression, leading to the disruption of cell growth processes. Smo-Shh aberrant signalling is responsible for several neurological complications contributing to physiological alterations like increased oxidative stress, neuronal excitotoxicity, neuroinflammation, and apoptosis. Moreover, activating Shh receptors in the brain promotes axonal elongation and increases neurotransmitters released from presynaptic terminals, thereby exerting neurogenesis, anti-oxidation, anti-inflammatory, and autophagy responses. Smo-Shh activators have been shown in preclinical and clinical studies to help prevent various neurodegenerative and neuropsychiatric disorders. Redox signalling has been found to play a critical role in regulating the activity of the Smo-Shh pathway and influencing downstream signalling events. In the current study ROS, a signalling molecule, was also essential in modulating the SMO-SHH gli signaling pathway in neurodegeneration. As a result of this investigation, dysregulation of the pathway contributes to the pathogenesis of various neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD).Thus, Smo-Shh signalling activators could be a potential therapeutic intervention to treat neurocomplications of brain disorders.

The Role of Dietary Antioxidants and Their Potential Mechanisms in Alzheimer’s Disease Treatment

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder associated with cognitive decline and characterized by amyloid-β plaques and neurofibrillary tau tangles. Although AD’s exact pathophysiology remains unclear, oxidative stress is known to play a role in the neurodegenerative process. Since no curative treatment exists, antioxidants represent a potential treatment for AD due to their ability to modulate oxidative stress. Therefore, this review aims to examine the impact of antioxidant supplementation and its potential mechanisms on cognitive function. The review primarily discusses research articles published between 2012 and 2022 reporting the results of clinical trials involving antioxidant supplementation on cognitive function in individuals with AD. Antioxidant supplementation included probiotics, selenium, melatonin, resveratrol, rosmarinic acid, carotenoids, curcumin, vitamin E, and coenzyme Q. While the studies included in this review did not provide much evidence for the beneficial role of antioxidant supplements on cognitive function in AD, the results varied from antioxidant to antioxidant and among trials examining the same antioxidant. Furthermore, many of the studies’ findings face several limitations, including short trial durations, small sample sizes, and a lack of diversity among study participants. As a result, more research is required to examine the impact of antioxidant supplementation on cognitive function in AD.

24-Hydroxycholesterol Induces Tau Proteasome-Dependent Degradation via the SIRT1/PGC1α/Nrf2 Pathway: A Potential Mechanism to Counteract Alzheimer’s Disease

Considerable evidence indicates that cholesterol oxidation products, named oxysterols, play a key role in several events involved in Alzheimer’s disease (AD) pathogenesis. Although the majority of oxysterols causes neuron dysfunction and degeneration, 24-hydroxycholesterol (24-OHC) has recently been thought to be neuroprotective also. The present study aimed at supporting this concept by exploring, in SK-N-BE neuroblastoma cells, whether 24-OHC affected the neuroprotective SIRT1/PGC1α/Nrf2 axis. We demonstrated that 24-OHC, through the up-regulation of the deacetylase SIRT1, was able to increase both PGC1α and Nrf2 expression and protein levels, as well as Nrf2 nuclear translocation. By acting on this neuroprotective pathway, 24-OHC favors tau protein clearance by triggering tau ubiquitination and subsequently its degradation through the ubiquitin–proteasome system. We also observed a modulation of SIRT1, PGC1α, and Nrf2 expression and synthesis in the brain of AD patients with the progression of the disease, suggesting their potential role in neuroprotection. These findings suggest that 24-OHC contributes to tau degradation through the up-regulation of the SIRT1/PGC1α/Nrf2 axis. Overall, the evidence points out the importance of avoiding 24-OHC loss, which can occur in the AD brain, and of limiting SIRT1, PGC1α, and Nrf2 deregulation in order to prevent the neurotoxic accumulation of hyperphosphorylated tau and counteract neurodegeneration.

Neuroprotective effects of sesamol against LPS-induced spatial learning and memory deficits are mediated via anti-inflammatory and antioxidant activities in the rat brain

Objective

Sesamol is a phenolic lignan extracted from sesame seeds, and it possesses anti-inflammatory and antioxidant activities. Lipopolysaccharide (LPS) is known to produce neuroinflammatory responses and memory impairment. The current study aimed to investigate the protective influence of sesamol against LPS-mediated neuroinflammation and memory impairment.

Materials and Methods

Sesamol (10 and 50 mg/kg) was injected to Wistar rats for two weeks. Then, animals received LPS injection (1 mg/kg) for five days, while treatment with sesamol was performed 30 min before LPS injection. Spatial learning and memory were assessed by the Morris water maze (MWM), two hours after LPS injection on days 15-19. Biochemical assessments were performed after the end of behavioral experiments.

Results

LPS-administered rats showed spatial learning and memory deficits, since they spent more time in the MWM to find the hidden platform and less time in the target quadrant. Besides these behavioral changes, tumor necrosis factor-α (TNF-α) and lipid peroxidation levels were increased, while total thiol level was decreased in the hippocampus and/or cerebral cortex. In addition, sesamol treatment (50 mg/kg) for three weeks decreased the escape latency and increased the time on probe trial. Sesamol also reduced lipid peroxidation and TNF-α level, while enhanced total thiol level in the brain of LPS-exposed rats.

Conclusion

Supplementation of sesamol attenuated learning and memory impairments in LPS-treated rats via antioxidative and anti-inflammatory activities in the rat brain.

NOX Dependent ROS Generation and Cell Metabolism

Reactive oxygen species (ROS) represent a group of high reactive molecules with dualistic natures since they can induce cytotoxicity or regulate cellular physiology. Among the ROS, the superoxide anion radical (O2·-) is a key redox signaling molecule prominently generated by the NADPH oxidase (NOX) enzyme family and by the mitochondrial electron transport chain. Notably, altered redox balance and deregulated redox signaling are recognized hallmarks of cancer and are involved in malignant progression and resistance to drugs treatment. Since oxidative stress and metabolism of cancer cells are strictly intertwined, in this review, we focus on the emerging roles of NOX enzymes as important modulators of metabolic reprogramming in cancer. The NOX family includes seven isoforms with different activation mechanisms, widely expressed in several tissues. In particular, we dissect the contribute of NOX1, NOX2, and NOX4 enzymes in the modulation of cellular metabolism and highlight their potential role as a new therapeutic target for tumor metabolism rewiring.

Amelioration of cognitive impairment using epigallocatechin-3-gallate in ovariectomized mice fed a high-fat diet involves remodeling with Prevotella and Bifidobacteriales

Background: Estrogen deficiency and a high-fat diet (HFD) are both risk factors for Alzheimer's disease (AD). HFD can accelerate cognitive impairment in estrogen-deficient patients, but there is currently no effective treatment. Epigallocatechin-3-galate (EGCG) is widely studied for its anti-inflammatory, anti-cancer, and anti-neurodegeneration effects. Nevertheless, whether EGCG can ameliorate cognitive impairment in HFD-fed estrogen-deficient mice has not been studied. Methods and Results: Ovariectomized (OVX) mice fed an HFD (HFOVX) for 8 weeks experienced impaired object recognition and spatial memory, but this damage was significantly attenuated by the administration of EGCG at a dose of 45 mg/kg. Through 16S rRNA gene sequencing, we found that HFOVX changed the diversity and structure of the gut microbiota in mice, which could be restored with EGCG. Further analysis showed that HFOVX exposure not only resulted in a decrease of Alloprevotella in Bacteroidetes, Lactobacillaceae in Firmicutes, and Prevotella in Bacteroidetes but also in an increase of Bifidobacteriales in Actinobacteria. EGCG effectively reversed the decrease of Prevotella and inhibited the increase of Bifidobacteriales but had no effect on the decrease of Alloprevotella or Lactobacillaceae or on the increase of Enterorhabdus in HFOVX mice. Additionally, using Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, we found that EGCG significantly reversed the five functional gut microbiota genes elevated by HFOVX, including iron complex transport system substrate-binding protein, iron complex transport system permease protein, 3-oxoacyl- [acyl-carrier protein] reductase, transketolase, and 8-oxo-dGTP diphosphatase. Conclusions: We concluded that EGCG improved cognitive impairment in mice with estrogen deficiency exacerbated by an HFD involved a rebuilding of the disrupted gut microbiota composition.

The impact of increasing levels of blood C-reactive protein on the inflammatory loci SPI1 and CD33 in Alzheimer's disease

Apolipoprotein ε4 (APOE ε4) is the most significant genetic risk factor for late-onset Alzheimer's disease (AD). Elevated blood C-reactive protein (CRP) further increases the risk of AD for people carrying the APOE ε4 allele. We hypothesized that CRP, as a key inflammatory element, could modulate the impact of other genetic variants on AD risk. We selected ten single nucleotide polymorphisms (SNPs) in reported AD risk loci encoding proteins related to inflammation. We then tested the interaction effects between these SNPs and blood CRP levels on AD incidence using the Cox proportional hazards model in UK Biobank (n = 279,176 white participants with 803 incident AD cases). The five top SNPs were tested for their interaction with different CRP cutoffs for AD incidence in the Framingham Heart Study (FHS) Generation 2 cohort (n = 3009, incident AD = 156). We found that for higher concentrations of serum CRP, the AD risk increased for SNP genotypes in 3 AD-associated genes (SPI1, CD33, and CLU). Using the Cox model in stratified genotype analysis, the hazard ratios (HRs) for the association between a higher CRP level (≥10 vs. <10 mg/L) and the risk of incident AD were 1.94 (95% CI: 1.33-2.84, p < 0.001) for the SPI1 rs1057233-AA genotype, 1.75 (95% CI: 1.20-2.55, p = 0.004) for the CD33 rs3865444-CC genotype, and 1.76 (95% CI: 1.25-2.48, p = 0.001) for the CLU rs9331896-C genotype. In contrast, these associations were not observed in the other genotypes of these genes. Finally, two SNPs were validated in 321 Alzheimer's Disease Neuroimaging (ADNI) Mild Cognitive Impairment (MCI) patients. We observed that the SPI1 and CD33 genotype effects were enhanced by elevated CRP levels for the risk of MCI to AD conversion. Furthermore, the SPI1 genotype was associated with CSF AD biomarkers, including t-Tau and p-Tau, in the ADNI cohort when the blood CRP level was increased (p < 0.01). Our findings suggest that elevated blood CRP, as a peripheral inflammatory biomarker, is an important moderator of the genetic effects of SPI1 and CD33 in addition to APOE ε4 on AD risk. Monitoring peripheral CRP levels may be helpful for precise intervention and prevention of AD for these genotype carriers.

Hyperbaric oxygen protects HT22 cells and PC12 cells from damage caused by oxygen-glucose deprivation/reperfusion via the inhibition of Nrf2/System Xc-/GPX4 axis-mediated ferroptosis

This study was to investigate the protective effect of hyperbaric oxygen (HBO) on HT22 and PC12 cell damage caused by oxygen-glucose deprivation/reperfusion-induced ferroptosis. A 2-h oxygen-glucose deprivation and 24-h reperfusion model on HT22 and PC12 cells was used to simulate cerebral ischemia-reperfusion injury. Cell viabilities were detected by Cell Counting Kit-8 (CCK-8) method. The levels of reactive oxygen species (ROS) and lipid reactive oxygen species (Lipid ROS) were detected by fluorescent probes Dihydroethidium (DHE) and C11 BODIPY 581/591. Iron Colorimetric Assay Kit, malondialdehyde (MDA) and glutathione (GSH) activity assay kits were used to detect intracellular iron ion, MDA and GSHcontent. Cell ferroptosis-related ultrastructures were visualized using transmission electron microscopy (TEM). Furthermore, PCR and Western blot analyses were used to detect the expressions of ferroptosis-related genes and proteins. After receiving oxygen-glucose deprivation/reperfusion, the viabilities of HT22 and PC12 cells were significantly decreased; ROS, Lipid ROS, iron ions and MDA accumulation occurred in the cells; GSH contents decreased; TEM showed that cells were ruptured and blebbed, mitochondria atrophied and became smaller, mitochondrial ridges were reduced or even disappeared, and apoptotic bodies appeared. And the expressions of Nrf2, SLC7A11 and GPX4 genes were reduced; the expressions of p-Nrf2/Nrf2, xCT and GPX4 proteins were reduced. Notably, these parameters were significantly reversed by HBO, indicating that HBO can protect HT22 cells and PC12 cells from damage caused by oxygen-glucosedeprivation/reperfusion via the inhibition of Nrf2/System Xc-/GPX4 axis-mediated ferroptosis.

Mixture of Tomato and Lemon Extracts Synergistically Prevents PC12 Cell Death from Oxidative Stress and Improves Hippocampal Neurogenesis in Aged Mice

Dietary habits have a great impact on one's health, especially in cognitive decline. Tomato and lemon contain diverse bioactive compounds and possess various effects, including the enhancement of cognitive function. We observed the protective effect of tomato, lemon extract and the mixture of them on H2O2-induced cytotoxicity of PC12 cells. To measure the in vivo effect in a murine model, each extract was orally administered to forty 1-year-old mice for 6 weeks, and a novel object recognition (NOR) test was performed to observe cognitive function, and hippocampal neurogenesis was observed through a doublecortin (DCX) stain. PC12 cell death by oxidative stress was reduced by pretreating with each extract, and a synergistic reduction was observed in the mixture. Newly generated DCX-positive neurons were synergistically increased in the hippocampus by the mixture. NOR test showed a tendency to significantly improve age-related cognitive dysfunction by consuming the mixture of tomato and lemon. In conclusion, tomato and lemon extracts can reduce cellular oxidative stress and increase NOR, likely due to enhanced neurogenesis, while the mixture of the two showed synergistic anti-oxidative effects and hippocampal neurogenesis.

In Vitro and In Vivo Neuroprotective Effects of Sarcosine

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by behavioral and psychological symptoms in addition to cognitive impairment and loss of memory. The exact pathogenesis and genetic background of AD are unclear and there remains no effective treatment option. Sarcosine, an n-methyl derivative of glycine, showed a promising therapeutic strategy for some cognitive disorders. To our knowledge, the impacts of sarcosine supplementation against AD have not yet been elucidated. Therefore, we aimed to determine the neuroprotective potential of sarcosine in in vitro and in vivo AD model. In vitro studies have demonstrated that sarcosine increased the percentage of viable cells against aluminum induced neurotoxicity. In AlCl₃-induced rat model of AD, the level of antioxidant capacity was significantly decreased and expression levels of APP, BACE1, TNF-α, APH1A, and PSENEN genes were elevated compared to the control group. Additionally, histopathological examinations of the hippocampus of AlCl₃-induced rat brains showed the presence of neurofibrillary tangles (NFTs). However, the administration of sarcosine produced marked improvement and protection of AD-associated pathologies induced by AlCl₃ in experimental rats. Therefore, this investigation may contribute to design novel therapeutic strategies using sarcosine for the management of AD pathologies.

Transepithelial transport and cellular mechanisms of food-derived antioxidant peptides

Considering the involvement of oxidative stress in the etiology of many non-communicable diseases, food-derived antioxidant peptides (FDAPs) are strong candidates for nutraceutical development for disease prevention and management. This paper reviews current evidence on the transepithelial transport and cellular mechanisms of antioxidant activities of FDAPs. Several FDAPs have multiple health benefits such as anti-inflammatory and anti-photoaging activities, in addition to antioxidant properties through which they protect cellular components from oxidative damage. Some FDAPs have been shown to permeate the intestinal epithelium, which could facilitate their bioavailability and physiological bioactivities. Molecular mechanisms of FDAPs include suppression of oxidative stress as evidenced by reduction in intracellular reactive oxygen species production, lipid peroxidation and apoptotic protein activation as well as increase in antioxidant defense mechanisms (enzymatic and non-enzymatic). Since many FDAPs have demonstrated promising antioxidant activity, future investigation should focus on further elucidation of molecular mechanisms and human studies to explore their practical application for the prevention and management of oxidative stress-related diseases.

Isorhamnetin Attenuated the Release of Interleukin-6 from β-Amyloid-Activated Microglia and Mitigated Interleukin-6-Mediated Neurotoxicity

Alzheimer's disease (AD), characterized by the abnormal accumulation of β-amyloid (Aβ), is the most prevalent type of dementia, and it is associated with progressive cognitive decline and memory loss. Aβ accumulation activates microglia, which secrete proinflammatory factors associated with Aβ clearance impairment and cause neurotoxicity, generating a vicious cycle among Aβ accumulation, activated microglia, and proinflammatory factors. Blocking this cycle can be a therapeutic strategy for AD. Using Aβ-activated HMC3 microglial cells, we observed that isorhamnetin, a main constituent of Oenanthe javanica, reduced the Aβ-triggered secretion of interleukin- (IL-) 6 and downregulated the expression levels of the microglial activation markers ionized calcium binding adaptor molecule 1 (IBA1) and CD11b and the inflammatory marker nuclear factor-κB (NF-κB). Treatment of the SH-SY5Y-derived neuronal cells with the Aβ-activated HMC3-conditioned medium (HMC3-conditioned medium) or IL-6 increased reactive oxygen species production, upregulated cleaved caspase 3 expression, and reduced neurite outgrowth, whereas treatment with isorhamnetin counteracted these neurodegenerative presentations. In the SH-SY5Y-derived neuronal cells, IL-6 upregulated the phosphorylation of tyrosine kinase 2 (TYK2) and signal transducer and activator of transcription 1 (STAT1), whereas isorhamnetin normalized this abnormal phosphorylation. Overexpression of TYK2 attenuated the neuroprotective effect of isorhamnetin on IL-6-induced neurotoxicity. Our findings demonstrate that isorhamnetin exerts its neuroprotective effect by mediating the neuroinflammatory IL-6/TYK2 signaling pathway, suggesting its potential for treating AD.

Recent Advances in the Neuroprotective Properties of Ferulic Acid in Alzheimer's Disease: A Narrative Review

Alzheimer's disease (AD) is a progressive degenerative disorder of the central nervous system, characterized by neuroinflammation, neurotransmitter deficits, and neurodegeneration, which finally leads to neuronal death. Emerging evidence highlighted that hyperglycemia and brain insulin resistance represent risk factors for AD development, thus suggesting the existence of an additional AD form, associated with glucose metabolism impairment, named type 3 diabetes. Owing to the limited pharmacological options, novel strategies, especially dietary approaches based on the consumption of polyphenols, have been addressed to prevent or, at least, slow down AD progression. Among polyphenols, ferulic acid is a hydroxycinnamic acid derivative, widely distributed in nature, especially in cereal bran and fruits, and known to be endowed with many bioactivities, especially antioxidant, anti-inflammatory and antidiabetic, thus suggesting it could be exploited as a possible novel neuroprotective strategy. Considering the importance of ferulic acid as a bioactive molecule and its widespread distribution in foods and medicinal plants, the aim of the present narrative review is to provide an overview on the existing preclinical and clinical evidence about the neuroprotective properties and mechanisms of action of ferulic acid, also focusing on its ability to modulate glucose homeostasis, in order to support a further therapeutic interest for AD and type 3 diabetes.

Gardeniae Fructus Extract Alleviates Dexamethasone-Induced Muscle Atrophy in Mice

Muscle atrophy (MA) is a case in which protein degeneration occurs excessively due to an imbalance between protein synthesis and breakdown, and is characterized by decreased muscle mass and weakened muscle strength. Despite mounting concern about MA, the number of patients with MA is increasing every year. The aim of the present study was to assess the impact of Gardeniae Fructus (GF) hot water extract on dexamethasone (DEX)-induced MA in mice. C57BL/6N mice were grouped (n = 8) as follows: Normal mice (Normal), MA mice were treated with distilled water (Control), MA mice were treated with GF 100 mg/kg (GF100), MA mice were treated with GF 200 mg/kg (GF200). For 10 days, DEX (25 mg/kg body weight, i.p.) injection was used to induce MA, and GF was administered. GF treatment restored the muscle weight decreased due to MA, and in particular, the weights of EDL+TA and Sol were significantly increased in the GF200 group. Also, it was confirmed that the swimming time was improved in the GF200 group. In addition, the expression of NADPH oxidase related to oxidative stress was significantly reduced, and protective (insulin-like growth factor I/phosphoinositide 3-kinase/protein kinase B pathway) and catabolic (AMP-activated kinase [AMPK]/sirtuin 1 [SIRT1]/proliferator-activated receptor-gamma coactivator-1α (PGC-1α)-forkhead box O (FOXO) pathway) pathways were significantly modulated. These results demonstrate that GF regulates muscle protein synthesis and catabolic pathways, and in particular, it is judged to improve MA by regulating the proteolytic AMPK/SIRT1/PGC-1α-FOXO pathway.

Serotonin 5-HT6 Receptor Ligands and Butyrylcholinesterase Inhibitors Displaying Antioxidant Activity-Design, Synthesis and Biological Evaluation of Multifunctional Agents against Alzheimer's Disease

Neurodegeneration leading to Alzheimer’s disease results from a complex interplay of a variety of processes including misfolding and aggregation of amyloid beta and tau proteins, neuroinflammation or oxidative stress. Therefore, to address more than one of these, drug discovery programmes focus on the development of multifunctional ligands, preferably with disease-modifying and symptoms-reducing potential. Following this idea, herein we present the design and synthesis of multifunctional ligands and biological evaluation of their 5-HT₆ receptor affinity (radioligand binding assay), cholinesterase inhibitory activity (spectroscopic Ellman’s assay), antioxidant activity (ABTS assay) and metal-chelating properties, as well as a preliminary ADMET properties evaluation. Based on the results we selected compound 14 as a well-balanced and potent 5-HT₆ receptor ligand (K_i = 22 nM) and human BuChE inhibitor (IC₅₀ = 16 nM) with antioxidant potential expressed as a reduction of ABTS radicals by 35% (150 μM). The study also revealed additional metal-chelating properties of compounds 15 and 18. The presented compounds modulating Alzheimer’s disease-related processes might be further developed as multifunctional ligands against the disease.

Synthesis, In Silico and Pharmacological Evaluation of New Thiazolidine-4-Carboxylic Acid Derivatives Against Ethanol-Induced Neurodegeneration and Memory Impairment

Introduction

Several studies revealed that alcohol utilization impairs memory in adults; however, the underlying mechanism is still unclear. The production of inflammatory markers and reactive oxygen species (ROS) plays a major role in neurodegeneration, which leads to memory impairment. Therefore, targeting neuroinflammation and oxidative distress could be a useful strategy for abrogating the hallmarks of ethanol-induced neurodegeneration. Moreover, several studies have demonstrated multiple biological activities of thiazolidine derivatives including neuroprotection.

Methods

In the current study, we synthesized ten (10) new thiazolidine-4-carboxylic acid derivatives (P1-P10), characterized their synthetic properties using proton nuclear magnetic resonance (¹H-NMR) and carbon-13 NMR, and further investigated the neuroprotective potential of these compounds in an ethanol-induced neuroinflammation model.

Results

Our results suggested altered levels of antioxidant enzymes associated with an elevated level of tumor necrosis factor-alpha (TNF-α), nuclear factor-κB (p-NF-κB), pyrin domain-containing protein 3 (NLRP3), and cyclooxygenase-2 (COX-2) in ethanol-treated animals. Ethanol treatment also led to memory impairment in rats, as assessed by behavioral tests. To further support our notion, we performed molecular docking studies, and all synthetic compounds exhibited a good binding affinity with a fair bond formation with selected targets (NF-κB, TLR4, NLRP3, and COX-2).

Discussion

Overall, our results revealed that these derivatives may be beneficial in reducing neuroinflammation by acting on different stages of inflammation. Moreover, P8 and P9 treatment attenuated the neuroinflammation, oxidative stress, and memory impairment caused by ethanol.

The Inflamm-Aging Model Identifies Key Risk Factors in Atherosclerosis

Background: Atherosclerosis, one of the main threats to human life and health, is driven by abnormal inflammation (i.e., chronic inflammation or oxidative stress) during accelerated aging. Many studies have shown that inflamm-aging exerts a significant impact on the occurrence of atherosclerosis, particularly by inducing an immune homeostasis imbalance. However, the potential mechanism by which inflamm-aging induces atherosclerosis needs to be studied more thoroughly, and there is currently a lack of powerful prediction models.

Methods: First, an improved inflamm-aging prediction model was constructed by integrating aging, inflammation, and disease markers with the help of machine learning methods; then, inflamm-aging scores were calculated. In addition, the causal relationship between aging and disease was identified using Mendelian randomization. A series of risk factors were also identified by causal analysis, sensitivity analysis, and network analysis.

Results: Our results revealed an accelerated inflamm-aging pattern in atherosclerosis and suggested a causal relationship between inflamm-aging and atherosclerosis. Mechanisms involving inflammation, nutritional balance, vascular homeostasis, and oxidative stress were found to be driving factors of atherosclerosis in the context of inflamm-aging.

Conclusion: In summary, we developed a model integrating crucial risk factors in inflamm-aging and atherosclerosis. Our computation pipeline could be used to explore potential mechanisms of related diseases.

Brain Protective Effect of Resveratrol via Ameliorating Interleukin-1β-Induced MMP-9-Mediated Disruption of ZO-1 Arranged Integrity

In the central nervous system (CNS), the matrix metalloproteinase-9 (MMP-9) is induced by several factors and contributes to CNS disorders, including inflammation and neurodegeneration. Thus, the upregulation of MMP-9 has been considered to be an indicator of inflammation. Interleukin-1β (IL-1β) is an important proinflammatory cytokine which can induce various inflammatory factors, such as MMP-9, in many inflammatory disorders. Several phytochemicals are believed to reduce the risk of several inflammatory disorders, including the CNS diseases. Among them, the resveratrol, a principal phenolic compound of the grape, blueberry, and mulberry peels and Cassia plants, has been shown to possess several medicinal properties, including antioxidative, anti-inflammatory, and antitumor function. Herein, we used mouse-brain microvascular endothelial cells (bMECs) to demonstrate the signaling mechanisms of IL-1β-induced MMP-9 expression via zymographic, RT-PCR, Western blot, reactive oxygen species (ROS) detection, immunofluorescence stain, and promoter reporter analyses. Then we evaluated the effects of resveratrol on IL-1β-induced MMP-9 expression in bMECs and its mechanism of action. We first demonstrated that IL-1β induced MMP-9 expression in bMECs. Subsequently, IL-1β induced MMP-9 expression via ROS-mediated c-Src-dependent transactivation of EGFR, and then activation of the ERK1/2, p38 MAPK, JNK1/2, and NF-κB signaling pathway. Finally, we determined that IL-1β-induced upregulation of MMP-9 may cause the disruption of the arranged integrity of zonula occludens-1 (ZO-1), but this could be inhibited by resveratrol. These data indicated that resveratrol may have antioxidative and brain-protective activities by reducing these related pathways of ROS-mediated MMP-9 expression and tight junction disruption in brain microvascular endothelial cells.

Oxidative stress: The core pathogenesis and mechanism of Alzheimer's disease

As the number of patients with Alzheimer's disease (AD) increases, it brings great suffering to their families and causes a heavy socioeconomic burden to society. A vast amount of funds and a mass of research have been devoted to elucidating the pathology of AD. However, the main pathogenesis is still elusive, and its mechanism is not completely clear. Research on the mechanisms of AD mainly focuses on the amyloid cascade, tau protein, neuroinflammation, metal ions, and oxidative stress hypotheses. Oxidative stress is as a bridge that connects the different hypotheses and mechanisms of AD. It is a process that causes neuronal damage and occurs in various pathways. Oxidative stress plays a critical role in AD and can even be considered a crucial central factor in the pathogenesis of AD. Previous reviews have also summarized the role of oxidative stress in AD, but these mainly review a specific signaling pathway. Taking oxidative stress as the central point, this review comprehensively expands on the roles of oxidative stress that are involved in the pathogenesis of AD. The vivid and easy-to-understand figures systematically clarify the connected roles of oxidative stress in AD and allow readers to further understand oxidative stress and AD.

Eugenitol ameliorates memory impairments in 5XFAD mice by reducing Aβ plaques and neuroinflammation

Alzheimer's disease (AD) is caused by various pathological mechanisms; therefore, it is necessary to develop drugs that simultaneously act on multiple targets. In this study, we investigated the effects of eugenitol, which has anti-amyloid β (Aβ) and anti-neuroinflammatory effects, in an AD mouse model. We found that eugenitol potently inhibited Aβ plaque and oligomer formation. Moreover, eugenitol dissociated the preformed Aβ plaques and reduced Aβ-induced nero2a cell death. An in silico docking simulation study showed that eugenitol may interact with Aβ1-42 monomers and fibrils. Eugenitol showed radical scavenging effects and potently reduced the release of proinflammatory cytokines from lipopolysaccharide-treated BV2 cells. Systemic administration of eugenitol blocked Aβ aggregate-induced memory impairment in the Morris water maze test in a dose-dependent manner. In 5XFAD mice, prolonged administration of eugenitol ameliorated memory and hippocampal long-term potentiation impairment. Moreover, eugenitol significantly reduced Aβ deposits and neuroinflammation in the hippocampus of 5XFAD mice. These results suggest that eugenitol, which has anti-Aβ aggregation, Aβ fibril dissociation, and anti-inflammatory effects, potently modulates AD-like pathologies in 5XFAD mice, and could be a promising candidate for AD therapy.

Thymoquinone: Review of Its Potential in the Treatment of Neurological Diseases

Thymoquinone (TQ) possesses anticonvulsant, antianxiety, antidepressant, and antipsychotic properties. It could be utilized to treat drug misuse or dependence, and those with memory and cognitive impairment. TQ protects brain cells from oxidative stress, which is especially pronounced in memory-related regions. TQ exhibits antineurotoxin characteristics, implying its role in preventing neurodegenerative disorders such as Alzheimer’s disease and Parkinson’s disease. TQ’s antioxidant and anti-inflammatory properties protect brain cells from damage and inflammation. Glutamate can trigger cell death by causing mitochondrial malfunction and the formation of reactive oxygen species (ROS). Reduction in ROS production can explain TQ effects in neuroinflammation. TQ can help prevent glutamate-induced apoptosis by suppressing mitochondrial malfunction. Several studies have demonstrated TQ’s role in inhibiting Toll-like receptors (TLRs) and some inflammatory mediators, leading to reduced inflammation and neurotoxicity. Several studies did not show any signs of dopaminergic neuron loss after TQ treatment in various animals. TQ has been shown in clinical studies to block acetylcholinesterase (AChE) activity, which increases acetylcholine (ACh). As a result, fresh memories are programmed to preserve the effects. Treatment with TQ has been linked to better outcomes and decreased side effects than other drugs.

Neurofilament Light Chain (NF-L) Stimulates Lipid Peroxidation to Neuronal Membrane through Microglia-Derived Ferritin Heavy Chain (FTH) Secretion

A part of the axonal cytoskeleton protein complex, neurofilament light chain (NF-L) has been suggested as a pathological hallmark in various neurological disorders, including hemorrhagic stroke, vascular dementia, and cerebral small vessel disease. Neuroaxonal debris are mainly engulfed and phagocytosed by microglia, while the effects of NF-L on microglia have not been elucidated. Ferritin heavy chain (FTH) not only reflects the age-related status of microglia but may also be secreted into the extracellular space. After treatment of microglia with varying concentrations of NF-L (0-3 μg/ml), we found robust increases in the number of secretory FTH-containing exosomes in the medium. Induction of the FTH-containing exosomes secreted from microglia stimulates neuronal loss and membrane lipid peroxidation, as assessed by CKK8 and C11-Bodipy^581/591, respectively. However, this oxidative stress damage was attenuated by blocking Fth1 expression. Our results suggest that NF-L, as a biomarker of axonal injury itself, could participate in neuronal ferroptosis in a nonclassical manner by secreting FTH-containing exosomes from microglia into the extracellular matrix.

Challenges and hopes for Alzheimer's disease

Recent drug development efforts targeting Alzheimer's disease (AD) have failed to produce effective disease-modifying agents for many reasons, including the substantial presymptomatic neuronal damage that is caused by the accumulation of the amyloid β (Aβ) peptide and tau protein abnormalities, deleterious adverse effects of drug candidates, and inadequate design of clinical trials. New molecular targets, biomarkers, and diagnostic techniques, as well as alternative nonpharmacological approaches, are sorely needed to detect and treat early pathological events. This article analyzes the successes and debacles of pharmaceutical endeavors to date, and highlights new technologies that may lead to the more effective diagnosis and treatment of the pathologies that underlie AD. The use of focused ultrasound, deep brain stimulation, stem cell therapy, and gene therapy, in parallel with pharmaceuticals and judicious lifestyle adjustments, holds promise for the deceleration, prevention, or cure of AD and other neurodegenerative disorders.

Improved synthesis of an ergothioneine PET radioligand for imaging oxidative stress in Alzheimer's disease

L-ergothioneine (ERGO) is a potent antioxidant with cytoprotective effects. To study ERGO biodistribution and detect oxidative stress in vivo, we report an efficient and reproducible preparation of [¹¹ C]-labeled ERGO PET radioligand based on protecting the histidine carboxylic group with a methyl ester. Overall, this new protection approach using methyl ester improved the chemical yield of a 4-step reaction from 14% to 24% compared to the previous report using t-butyl ester. The [¹¹ C]CH₃ methylation of the precursor provided the desired product with 55 ± 10% radiochemical purity and a molar activity of 450 ± 200 TBq/mmol. The [¹¹ C]ERGO radioligand was able to detect threshold levels of oxidative stress in a preclinical animal model of Alzheimer's disease.

Understanding the Emerging Link Between Circadian Rhythm, Nrf2 Pathway, and Breast Cancer to Overcome Drug Resistance

The levels of different molecules in the cell are rhythmically cycled by the molecular clock present at the cellular level. The circadian rhythm is closely linked to the metabolic processes in the cells by an underlying mechanism whose intricacies need to be thoroughly investigated. Nevertheless, Nrf2 has been identified as an essential bridge between the circadian clock and cellular metabolism and is activated by the by-product of cellular metabolism like hydrogen peroxide. Once activated it binds to the specific DNA segments and increases the transcription of several genes that play a crucial role in the normal functioning of the cell. The central clock located in the suprachiasmatic nucleus of the anterior hypothalamus synchronizes the timekeeping in the peripheral tissues by integrating the light-dark input from the environment. Several studies have demonstrated the role of circadian rhythm as an effective tumor suppressor. Tumor development is triggered by the stimulation or disruption of signaling pathways at the cellular level as a result of the interaction between cells and environmental stimuli. Oxidative stress is one such external stimulus that disturbs the prooxidant/antioxidant equilibrium due to the loss of control over signaling pathways which destroy the bio-molecules. Altered Nrf2 expression and impaired redox balance are associated with various cancers suggesting that Nrf2 targeting may be used as a novel therapeutic approach for treating cancers. On the other hand, Nrf2 has also been shown to enhance the resistance of cancer cells to chemotherapeutic agents. We believe that maximum efficacy with minimum side effects for any particular therapy can be achieved if the treatment strategy regulates the circadian rhythm. In this review, we discuss the various molecular mechanisms interlinking the circadian rhythm with the Nrf2 pathway and contributing to breast cancer pathogenesis, we also talk about how these two pathways work in close association with the cell cycle which is another oscillatory system, and whether this interplay can be exploited to overcome drug resistance during chemotherapy.

Unifying mechanism behind the onset of acquired epilepsy

Acquired epilepsy (AE) can result from a number of brain insults and neurological diseases with wide etiological diversity sharing one common outcome of brain epileptiform activity. This implies that despite their disparity, all these initiating pathologies affect the same fundamental brain functions underlying network excitability. Identifying such mechanisms and their availability as therapeutic targets would help develop an effective strategy for epileptogenesis prevention. In this opinion article, we propose that the vicious cycle of NADPH oxidase (NOX)-mediated oxidative stress and glucose hypometabolism is the underlying cause of AE, as available data reveal a critical role for both pathologies in epileptogenesis and the process of seizure initiation. Altogether, here we present a novel view on the mechanisms behind the onset of AE and identify therapeutic targets for potential clinical applications.

Novel organoselenides (NSAIDs-Se derivatives) protect against LPS-induced inflammation in microglia by targeting the NOX2/NLRP3 signaling pathway

Neuro-inflammation is an immune response of the central nervous system (CNS) to pathogens, and it is associated with a variety of neurodegenerative diseases. Microglial cells are the main category of macrophages in the CNS parenchyma, and they represent one of the most important cellular drivers and regulators of neuroinflammation. In this study, nine new organoselenium compounds based on the hybridization of nonsteroidal anti-inflammatory drugs (NSAIDs) skeleton and organoselenium motif (-SeCN and -SeCF3) were synthesized and their potential anti-neuroinflammatory effects were evaluated using LPS-induced BV2 mouse microglia. The cells were first treated with the organoselenium compounds and the extent of oxidative stress and inflammatory response of the cells was determined by measuring the levels of NO, ROS, IL-1β, and IL-18. Among the nine compounds, 1-39 and 1A-38 exhibited the most significant effect on oxidative stress and inflammatory response. Subsequent studies carried out with 1-39 and 1A-38 showed that both compounds could reduce the production of ROS in the cells, probably through down-regulating NOX2 and its downstream targets, including TXNIP (thioredoxin-interacting protein) and NLRP3 (NOD-like receptor protein 3). In addition, 1-39 and 1A-38 also suppressed the ability of the cells to secret IL-18 and IL-1β, which greatly dampened the response of the cells to LPS-induced inflammation. Our finding demonstrated that organoselenium compounds derived from NSAID might play an important role in the protection of brain microglia against inflammation-related neurodegenerative disease by potentially down-regulating the NOX2/NLRP3 signaling axis.

Novel Hydroxytyrosol-Donepezil Hybrids as Potential Antioxidant and Neuroprotective Agents

It is well-accepted that the endogenous antioxidant protection system progressively decays in elderly people, and that the oxidative stress contributes to different neurodegenerative disorders such as Alzheimer’s Diseases (AD). The lower incidence of AD in countries which feature the Mediterranean Diet was associated to the high consumption of extra virgin olive oil and its polyphenolic fraction, in particular hydroxytyrosol. The protective role of these bio-phenols against oxidative stress, suggested that we combine their antioxidant/free radical scavenging activity with donepezil, an active ingredient which has just been approved for the treatment of AD. Different synthetic strategies were tested to conjugate the two different synthons in good yields. Additionally, a nitro-hydroxytyrosol derivative was synthesized to extend the application to other neurodegeneration inflammatory models. Then, their bioactivity was measured in different chemical and biological tests on a human neuroblastoma cell line (SHSY-5Y). Remarkable results on cell viability and the regulation of the redox state of cells were obtained. All hybrids showed negligible cell death under 1 μM and are stable and non toxic. Reactive oxygen species (ROS) measurements showed that the nitro-hybrid was the more effective one at reducing the ROS amount to physiological values. Then, in light of the bio-metal hypothesis of diverse neurodegenerative disorders, we tested these new compounds on the chelation properties of redox-active metals. The nitro-hybrid was able to chelate all of the tested metal cations, suggesting that we propose it as potential lead compound for a new class of neuroprotective antioxidant agents.