Neuroinflammation in pathogenesis of Alzheimer's disease: Phytochemicals as potential therapeutics

Neuroprotective Effects of Chemical Constituents of Leaves of Euonymus hamiltonianus Wall

Euonymus hamiltonianus Wall. is considered a medicinal plant and is used to treat pain, cough, dysuria, and cancer, but a clear phytochemical investigation of its biological activities has yet to be performed. Investigation of chemical constituents of the leaves of Euonymus hamiltonianus Wall. led to the isolation of three new compounds by chromatography techniques, euonymusins A-C (1, 10, and 11), and the acquisition of new spectroscopic data for euonymusin D (2), along with the identification of ten known compounds. The chemical structures of the compounds were established using extensive spectroscopic techniques, including NMR, MS, and hydrolysis, and compared with the published data. These compounds were tested in vitro for their inhibitory effects on beta amyloid production (Aβ42). Compounds 13 and 14 displayed weak inhibition, with IC50 values ranging from 53.15 to 65.43 µM. Moreover, these compounds were also assessed for their inhibitory effects on nitric oxide production. Of these compounds, 3, 4, and 14 displayed inhibitory effects on NO production, with IC50 values ranging from 14.38 to 17.44 µM. Compounds 3, 4, and 14 also suppressed LPS-induced expression of nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein.

Associations Between Neuroinflammation-Related Conditions and Alzheimer's Disease: A Study of US Insurance Claims Data

Background

Early detection of Alzheimer's disease (AD) is a key component for the success of the recently approved lecanemab and aducanumab. Patients with neuroinflammation-related conditions are associated with a higher risk for developing AD.

Objective

Investigate the incidence of AD among patients with neuroinflammation-related conditions including epilepsy, hemorrhage stroke, multiple sclerosis (MS), and traumatic brain injury (TBI).

Methods

We used Optum's de-identified Clinformatics Data Mart Database (CDM). We derived covariate-matched cohorts including patients with neuroinflammation-related conditions and controls without the corresponding condition. The matched cohorts were: 1) patients with epilepsy and controls (N = 67,825 matched pairs); 2) patients with hemorrhage stroke and controls (N = 81,510 matched pairs); 3) patients with MS and controls (N = 9,853 matched pairs); and 4) patients TBI and controls (N = 104,637 matched pairs). We used the Cox model to investigate the associations between neuroinflammation-related conditions and AD.

Results

We identified that epilepsy, hemorrhage stroke, and TBI were associated with increased risks of AD in both males and females (hazard ratios [HRs]≥1.74, p < 0.001), as well as in gender- and race-conscious subpopulations (HRs≥1.64, p < 0.001). We identified that MS was associated with increased risks of AD in both males and females (HRs≥1.47, p≤0.004), while gender- and race-conscious subgroup analysis shown mixed associations.

Conclusions

Patients with epilepsy, hemorrhage stroke, MS, and/or TBI are associated with a higher risk of developing AD. More attention on cognitive status should be given to older patients with these conditions.

The Standardized Extract of Centella asiatica and Its Fractions Exert Antioxidative and Anti-Neuroinflammatory Effects on Microglial Cells and Regulate the Nrf2/HO-1 Signaling Pathway

Background

Neuroinflammation and oxidative stress can aggravate the progression of Alzheimer's disease (AD). Centella asiatica has been traditionally consumed for memory and cognition. The triterpenes (asiaticoside, madecassoside, asiatic acid, madecassic acid) have been standardized in the ethanolic extract of Centella asiatica (SECA). The bioactivity of the triterpenes in different solvent polarities of SECA is still unknown.

Objective

In this study, the antioxidative and anti-neuroinflammatory effects of SECA and its fractions were explored on lipopolysaccharides (LPS)-induced microglial cells.

Methods

HPLC measured the four triterpenes in SECA and its fractions. SECA and its fractions were tested for cytotoxicity on microglial cells using MTT assay. NO, pro-inflammatory cytokines (TNF-α, IL-6, IL-1β), ROS, and MDA (lipid peroxidation) produced by LPS-induced microglial cells were measured by colorimetric assays and ELISA. Nrf2 and HO-1 protein expressions were measured using western blotting.

Results

The SECA and its fractions were non-toxic to BV2 microglial cells at tested concentrations. The levels of NO, TNF-α, IL-6, ROS, and lipid peroxidation in LPS-induced BV2 microglial cells were significantly reduced (p < 0.001) by SECA and its fractions. SECA and some of its fractions can activate the Nrf2/HO-1 signaling pathway by significantly enhancing (p < 0.05) the Nrf2 and HO-1 protein expressions.

Conclusions

This study suggests that the inhibitory activity of SECA and its fractions on pro-inflammatory and oxidative stress events may be the result of the activation of antioxidant defense systems. The potential of SECA and its fractions in reducing neuroinflammation and oxidative stress can be further studied as a potential therapeutic strategy for AD.

Underlying Mechanisms of Brain Aging and Neurodegenerative Diseases as Potential Targets for Preventive or Therapeutic Strategies Using Phytochemicals

During aging, several tissues and biological systems undergo a progressive decline in function, leading to age-associated diseases such as neurodegenerative, inflammatory, metabolic, and cardiovascular diseases and cancer. In this review, we focus on the molecular underpinning of senescence and neurodegeneration related to age-associated brain diseases, in particular, Alzheimer's and Parkinson's diseases, along with introducing nutrients or phytochemicals that modulate age-associated molecular dysfunctions, potentially offering preventive or therapeutic benefits. Based on current knowledge, the dysregulation of microglia genes and neuroinflammation, telomere attrition, neuronal stem cell degradation, vascular system dysfunction, reactive oxygen species, loss of chromosome X inactivation in females, and gut microbiome dysbiosis have been seen to play pivotal roles in neurodegeneration in an interactive manner. There are several phytochemicals (e.g., curcumin, EGCG, fucoidan, galangin, astin C, apigenin, resveratrol, phytic acid, acacetin, daucosterol, silibinin, sulforaphane, withaferin A, and betulinic acid) that modulate the dysfunction of one or several key genes (e.g., TREM2, C3, C3aR1, TNFA, NF-kb, TGFB1&2, SIRT1&6, HMGB1, and STING) affected in the aged brain. Although phytochemicals have shown promise in slowing down the progression of age-related brain diseases, more studies to identify their efficacy, alone or in combinations, in preclinical systems can help to design novel nutritional strategies for the management of neurodegenerative diseases in humans.

Insights into prevention mechanisms of bioactive components from healthy diets against Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease in which senile plaques, neurofibrillary tangles, insulin resistance, oxidative stress, chronic neuroinflammation, and abnormal neurotransmission are the potential mechanisms involved in its onset and development. Although it is still an intractable disorder, diet intervention has been developed as an innovative strategy for AD prevention. Some bioactive compounds and micronutrients from food, including soy isoflavones, rutin, vitamin B1, etc., have exhibited numerous neuronal health-promoting effects in both in vivo and in vitro studies. It is well known that their antiapoptotic, antioxidative, and anti-inflammatory properties prevent the neuronal or glial cells from injury or death, minimize oxidative damage, inhibit the production of proinflammatory cytokines by modulating typical signaling pathways of MAPK, NF-kβ, and TLR, and further reduce Aβ genesis and tau hyperphosphorylation. However, parts of the dietary components trigger AD-related proteins productions and inflammasome as well as inflammatory gene upregulation. This review summarized the neuroprotective or nerve damage-promoting role and underlying molecular mechanisms of flavonoids, vitamins, and fatty acids via the data from library databases, PubMed, and journal websites, which provides a comprehensive analysis of the prevention potential of these dietary components against AD.

Senopathies-Diseases Associated with Cellular Senescence

Cellular senescence describes a stable cell cycle arrest state with a characteristic phenotype. Senescent cells accumulate in the human body during normal aging, limiting the lifespan and promoting aging-related, but also several non-related, pathologies. We propose to refer to all diseases whose pathogenesis or progression is associated with cellular senescence as "senopathies". Targeting senescent cells with senolytics or senomorphics is likely to mitigate these pathologies. Examples of senopathies include cardiovascular, metabolic, musculoskeletal, liver, kidney, and lung diseases and neurodegeneration. For all these pathologies, animal studies provide clear mechanistic evidence for a connection between senescent cell accumulation and disease progression. The major persisting challenge in developing novel senotherapies is the heterogeneity of senescence phenotypes, causing a lack of universal biomarkers and difficulties in discriminating senescent from non-senescent cells.

How can we modulate aging through nutrition and physical exercise? An epigenetic approach

The World Health Organization predicts that by 2050, 2.1 billion people worldwide will be over 60 years old, a drastic increase from only 1 billion in 2019. Considering these numbers, strategies to ensure an extended "healthspan" or healthy longevity are urgently needed. The present study approaches the promotion of healthspan from an epigenetic perspective. Epigenetic phenomena are modifiable in response to an individual's environmental exposures, and therefore link an individual's environment to their gene expression pattern. Epigenetic studies demonstrate that aging is associated with decondensation of the chromatin, leading to an altered heterochromatin structure, which promotes the accumulation of errors. In this review, we describe how aging impacts epigenetics and how nutrition and physical exercise can positively impact the aging process, from an epigenetic point of view. Canonical histones are replaced by histone variants, concomitant with an increase in histone post-translational modifications. A slight increase in DNA methylation at promoters has been observed, which represses transcription of previously active genes, in parallel with global genome hypomethylation. Aging is also associated with deregulation of gene expression - usually provided by non-coding RNAs - leading to both the repression of previously transcribed genes and to the transcription of previously repressed genes. Age-associated epigenetic events are less common in individuals with a healthy lifestyle, including balanced nutrition, caloric restriction and physical exercise. Healthy aging is associated with more tightly condensed chromatin, fewer PTMs and greater regulation by ncRNAs.

Neuroprotective Potentials of Flavonoids: Experimental Studies and Mechanisms of Action

Neurological and neurodegenerative diseases, particularly those related to aging, are on the rise, but drug therapies are rarely curative. Functional disorders and the organic degeneration of nervous tissue often have complex causes, in which phenomena of oxidative stress, inflammation and cytotoxicity are intertwined. For these reasons, the search for natural substances that can slow down or counteract these pathologies has increased rapidly over the last two decades. In this paper, studies on the neuroprotective effects of flavonoids (especially the two most widely used, hesperidin and quercetin) on animal models of depression, neurotoxicity, Alzheimer's disease (AD) and Parkinson's disease are reviewed. The literature on these topics amounts to a few hundred publications on in vitro and in vivo models (notably in rodents) and provides us with a very detailed picture of the action mechanisms and targets of these substances. These include the decrease in enzymes that produce reactive oxygen and ferroptosis, the inhibition of mono-amine oxidases, the stimulation of the Nrf2/ARE system, the induction of brain-derived neurotrophic factor production and, in the case of AD, the prevention of amyloid-beta aggregation. The inhibition of neuroinflammatory processes has been documented as a decrease in cytokine formation (mainly TNF-alpha and IL-1beta) by microglia and astrocytes, by modulating a number of regulatory proteins such as Nf-kB and NLRP3/inflammasome. Although clinical trials on humans are still scarce, preclinical studies allow us to consider hesperidin, quercetin, and other flavonoids as very interesting and safe dietary molecules to be further investigated as complementary treatments in order to prevent neurodegenerative diseases or to moderate their deleterious effects.

Impact of free curcumin and curcumin nanocapsules on viability and oxidative status of neural cell lines

Curcumin is an active polyphenol substance found in the highest concentrations in the roots of Curcuma longa. Its health benefits have led to recent increases in the consumption of curcumin. It has anti-inflammatory and antioxidant activities and is a potent neuroprotective against diseases of the brain. Nevertheless, its low bioavailability and its relative difficulty crossing the blood-brain barrier limit curcumin's use for these purposes. Curcumin-loaded nanoparticles may be an effective treatment for several diseases although there is a paucity of studies reporting its safety in the central nervous system (CNS). Therefore, this study aimed to identify non-neurotoxic concentrations of free curcumin and two nanoformulations of curcumin. Cell lines BV-2 and SH-SY5Y, both originating from the CNS, were evaluated after 24, 48, and 72 h of treatment with free curcumin and nanocapsules We measured viability, proliferation, and dsDNA levels. We measured levels of reactive oxygen species and nitric oxide as proxies for oxidative stress in culture supernatants. We found that free curcumin was toxic at 10 and 20 µM, principally at 72 h. Nanoformulations were more neurotoxic than the free form. Safe concentrations of free curcumin are between 1-5 µM, and these concentrations were lower for nanoformulations. We determined the ideal concentrations of free curcumin and nanocapsules serving as a basis for studies of injuries that affect the CNS.

Advances in the roles and mechanisms of lignans against Alzheimer’s disease

Background: Alzheimer’s disease (AD) is a serious neurodegenerative disease associated with the memory and cognitive impairment. The occurrence of AD is due to the accumulation of amyloid β-protein (Aβ) plaques and neurofibrillary tangles (NFTs) in the brain tissue as well as the hyperphosphorylation of Tau protein in neurons, doing harm to the human health and even leading people to death. The development of neuroprotective drugs with small side effects and good efficacy is focused by scientists all over the world. Natural drugs extracted from herbs or plants have become the preferred resources for new candidate drugs. Lignans were reported to effectively protect nerve cells and alleviate memory impairment, suggesting that they might be a prosperous class of compounds in treating AD.

Objective: To explore the roles and mechanisms of lignans in the treatment of neurological diseases, providing proofs for the development of lignans as novel anti-AD drugs.

Methods: Relevant literature was extracted and retrieved from the databases including China National Knowledge Infrastructure (CNKI), Elsevier, Science Direct, PubMed, SpringerLink, and Web of Science, taking lignan, anti-inflammatory, antioxidant, apoptosis, nerve regeneration, nerve protection as keywords. The functions and mechanisms of lignans against AD were summerized.

Results: Lignans were found to have the effects of regulating vascular disorders, anti-infection, anti-inflammation, anti-oxidation, anti-apoptosis, antagonizing NMDA receptor, suppressing AChE activity, improving gut microbiota, so as to strengthening nerve protection. Among them, dibenzocyclooctene lignans were most widely reported and might be the most prosperous category in the develpment of anti-AD drugs.

Conclusion: Lignans displayed versatile roles and mechanisms in preventing the progression of AD in in vitro and in vivo models, supplying potential candidates for the treatment of nerrodegenerative diseases.

Multi-Target Mechanisms of Phytochemicals in Alzheimer’s Disease: Effects on Oxidative Stress, Neuroinflammation and Protein Aggregation

Alzheimer’s disease (AD) is a neurodegenerative disease characterized by a tangle-shaped accumulation of beta-amyloid peptide fragments and Tau protein in brain neurons. The pathophysiological mechanism involves the presence of Aβ-amyloid peptide, Tau protein, oxidative stress, and an exacerbated neuro-inflammatory response. This review aims to offer an updated compendium of the most recent and promising advances in AD treatment through the administration of phytochemicals. The literature survey was carried out by electronic search in the following specialized databases PubMed/Medline, Embase, TRIP database, Google Scholar, Wiley, and Web of Science regarding published works that included molecular mechanisms and signaling pathways targeted by phytochemicals in various experimental models of Alzheimer’s disease in vitro and in vivo. The results of the studies showed that the use of phytochemicals against AD has gained relevance due to their antioxidant, anti-neuroinflammatory, anti-amyloid, and anti-hyperphosphorylation properties of Tau protein. Some bioactive compounds from plants have been shown to have the ability to prevent and stop the progression of Alzheimer’s.

Neuroprotective Effects of Phytochemicals against Aluminum Chloride-Induced Alzheimer’s Disease through ApoE4/LRP1, Wnt3/β-Catenin/GSK3β, and TLR4/NLRP3 Pathways with Physical and Mental Activities in a Rat Model

Background: Alzheimer’s disease (AD) is a neurodegenerative disorder that is associated with abnormal cognition. AD is aided in its initiation and progression by hereditary and environmental factors. Aluminum (Al) is a neurotoxic agent that causes oxidative stress, which is linked to AD progression. Additionally, Nrf2/HO-1, APOE4/LRP1, Wnt3/β-catenin, and TLR4/NLRP3 are the main signaling pathways involved in AD pathogenesis. Several phytochemicals are promising options in delaying AD evolution. Objectives: This study aimed at studying the neuroprotective effects of some phytochemicals as morin (MOR), thymol (TML), and thymoquinone (TMQ) on physical and mental activities (PhM) in Al chloride (AlCl₃)-induced AD rat model. Another objective was to determine the specificity of phytochemicals to AD signaling pathways using molecular docking. Methods: Eighty male Dawley rats were divided into eight groups. Each group received: saline (control group), AlCl₃, (ALAD), PhM, either alone or with a combination of MOR, TML, and/or TMQ for five weeks. Animals were then subjected to behavioral evaluation. Brain tissues were used for histopathological and biochemical analyses to determine the extent of neurodegeneration. The effect of phytochemicals on AlCl₃-induced oxidative stress and the main signaling pathways involved in AD progression were also investigated. Results: AlCl₃ caused a decline in spatial learning and memory, as well as histopathological changes in the brains of rats. Phytochemicals combined with PhM restored antioxidant activities, increased HO-1 and Nrf2 levels, blocked inflammasome activation, apoptosis, TLR4 expression, amyloide-β generation, and tau hyperphophorylation. They also brought ApoE4 and LRP1 levels back to normal and regulated Wnt3/β-catenin/GSK3β signaling pathway. Conclusions: The use of phytochemicals with PhM is a promising strategy for reducing AD by modulating Nrf2/HO-1, TLR4/NLRP3, APOE4/LRP1, and Wnt3/β-catenin/GSK-3β signaling pathways.

Critical appraisal on mitochondrial dysfunction in Alzheimer's disease

It is widely recognized that Alzheimer's disease (AD) is a common type of progressive neurodegenerative disorder that results in cognitive impairment over time. Approximately 152 million cases of AD are predicted to be reported by 2050. Amyloid plaques and tau proteins are two major hallmarks of AD which can be seen under electron microscope. Mitochondria plays a vital role in the pathogenesis of AD and mitochondria disruption leads to mitochondrial DNA (mtDNA) dysfunction, alteration of mitochondria dependent Ca2+ homeostasis, copper dysfunction, immune cell dysfunction, etc. In this review, we try to cover all the mechanisms related with mitochondrial dysfunction and mitochondrial pathogenesis that may help us to better understand AD as well as open a new era for therapeutic target of AD and treat this progressive disease.

Potential of flavonoids as anti-Alzheimer's agents: bench to bedside

Developing therapies for neurodegenerative diseases are challenging because of the presence of blood-brain barrier and Alzheimer being one of the commonest and uprising neurodegenerative disorders possess the need for developing novel therapies. Alzheimer's is attributed to be the sixth leading cause of death in the USA and the number of cases is estimated to be increased from 58 million in 2021 to 88 million by 2050. Natural drugs have benefits of being cost-effective, widely available, fewer side effects, and immuno-booster can be useful in managing Alzheimer. Flavonoids can slow the neuronal degeneration as they have shown activity in central nervous system and are able to cross the blood-brain barrier. These can be easily extracted from fruits, vegetable, and plants. In Alzheimer disease, flavonoids scavenges the reactive oxygen species and reduces the production of amyloid beta protein. Agents from sub-classes of flavonoids such as flavanones, flavanols, flavones, flavonols, anthocyanins, and isoflavones having pharmacological action in treating Alzheimer disease are discussed in this review.

Identification of NLRP3 as a covalent target of 1,6-O,O-diacetylbritannilactone against neuroinflammation by quantitative thiol reactivity profiling (QTRP)

Neuroinflammation plays a key etiological role in the progressive neuronal damage of neurodegenerative diseases. Our phenotypic-based screening discovered 1,6-O,O-diacetylbritannilactone (OABL, 1) from Inula britannica exhibited the potential anti-neuroinflammatory activity as well as a favorable blood-brain barrier penetration. 1 and its active derivative Br-OABL (2) with insert of Br at the C-14 position both modulated TLR4/NF-kB/MAPK pathways. However, proteome-wide identification of 1 binding proteins remains unclear. Here, we employed an adapted isoTOP-ABPP, quantitative thiol reactivity profiling (QTRP) approach, to identify and quantify thiol reactivity binding proteins in murine microglia BV-2 cells. We screened out 15 proteins co-targeted by 1 and 2, which are involved in cellular response to oxidative stress and negative regulation NF-κB transcription factor in biological processes. In site-specific profiling, NLRP3 was identified as a covalent target of 1 and 2 for the first time, and the Cys⁴⁸³ of NLRP3 NACHT domain was identified as one active-site of NLRP3 cysteine residues that can be covalently modified by the α-methylene-γ-lactone moiety. Furthermore, NLRP3 was validated to be directly binded by 1 and 2 by cellular thermo shift assay (CETSA) and activity-based protein profiling (ABPP), and NLRP3 functions were also verified by small interfering RNA approach. Notably, OABL treatment (i.p., 20 mg/kg/day) for 21 days reduced inflammation in 5XFAD mice brain. Together, we applied the QTRP to uncover the binding proteins of OABL in BV-2 cells, among which NLRP3 was revealed as a new covalent target of 1 and 2 against neuroinflammation.

An integrative review on the uses of plant-derived bioactives formulated in conventional and innovative dosage forms for the local treatment of damaged nasal cavity

Plants and their derivates have been used as medicines for centuries and today is being re-discovered their usefulness for the human health. The therapeutic properties of phytochemicals are re-evaluated under the light of medical and pharmacological research, pushed by a constantly growing market demand, where consumers trust more natural products than synthetic drugs. New studies are enlightening the effectiveness of phytochemicals against a wide range of ailments, nevertheless very few evaluate the efficacy of topical formulations based on natural bioactive molecules in the treatment of nasal mucosal diseases. This review aims at exploring this little covered topic. An overview on the properties and functionality of the nasal mucosa and the different diseases affecting it has been provided. We summarized various nasal dosage forms containing natural bioactive and explored how innovative delivery systems loading phytochemicals can improve the treatment results. Finally, the potential use of novel nanocarriers for the treatment of nasal ailments has been covered as well.

Eugenol Elicits Prolongevity by Increasing Resistance to Oxidative Stress in C. elegans

AIM

To analyze the efficacy of eugenol on longevity by assessing its antioxidant effect using Caenorhabditis elegans as an animal model.

BACKGROUND

Eugenol is a major polyphenolic component of Ocimum sanctum (Tulsi) which attributes wide pharmacological activities and can serve as a biomarker. However, the possible effect of eugenol on longevity in Caenorhabditis elegans has not been reported.

OBJECTIVE

The objective of this investigation was to provide first scientific based results about effect of eugenol on longevity, slowing down of paralysis in Alzheimer's model and mechanism behind it in Caenorhabditis elegans animal model system.

METHODS

The phenolic components of methanolic extract of Ocimum sanctum was analyzed by RP-HPLC. Worms were exposed to different concentrations of extract and one of its components -eugenol. Lifespan, health span, survival in CL4176 Alzheimer's model and molecular mechanism were analyzed.

RESULTS

Extract of Ocimum sanctumand eugenol increased lifespan and provided indemnity against pro-oxidants. It also significantly improved healthy ageing and slowed the progression of neurodegeneration in CL4176 Alzheimer's model of worm by increasing survival against prooxidants and slowing down the paralysis. Longevity effect was independent of the DAF-16 as observed by using DAF-16::GFP and daf-16 null mutant strains. These results implicate eugenol as a potent therapeutic compound which may curtail ageing and age related disorders like- Alzheimer's disease.

CONCLUSION

The present work demonstrated eugenol as a potential anti-ageing compound which may curtail ageing, improve heath span by enhancing resistance to oxidative stress and exerts its effect independent of DAF-16 pathway. So, it can be assumed that eugenol can be beneficial to humans as well, albeit further research is necessary before declaring it for human consumption.

Natural sweetener Stevia rebaudiana: Functionalities, health benefits and potential risks

Stevia rebaudiana is a South American plant, the cultivation of which is increasing worldwide due to its high content of sweet compounds. Stevia sweetness is mainly due to steviol glycosides, that are ~250-300 times sweeter than sucrose. Many studies have suggested the benefits of Stevia extract over sugar and artificial sweeteners, but it is still not a very popular sugar substitute. This review summarizes current data on the biological activities of S. rebaudiana extract and its individual glycosides, including anti-hypertensive, anti-obesity, anti-diabetic, antioxidant, anti-cancer, anti-inflammatory, and antimicrobial effects and improvement of kidney function. Possible side effects and toxicity of Stevia extract are also discussed.

Control of hippocampal prothrombin kringle-2 (pKr-2) expression reduces neurotoxic symptoms in five familial Alzheimer's disease mice

Background and Purpose

There is a scarcity of information regarding the role of prothrombin kringle‐2 (pKr‐2), which can be generated by active thrombin, in hippocampal neurodegeneration and Alzheimer's disease (AD).

Experimental Approach

To assess the role of pKr‐2 in association with the neurotoxic symptoms of AD, we determined pKr‐2 protein levels in post‐mortem hippocampal tissues of patients with AD and the hippocampi of five familial AD (5XFAD) mice compared with those of age‐matched controls and wild‐type (WT) mice, respectively. In addition, we investigated whether the hippocampal neurodegeneration and object memory impairments shown in 5XFAD mice were mediated by changes to pKr‐2 up‐regulation.

Key Results

Our results demonstrated that pKr‐2 was up‐regulated in the hippocampi of patients with AD and 5XFAD mice, but was not associated with amyloid‐β aggregation in 5XFAD mice. The up‐regulation of pKr‐2 expression was inhibited by preservation of the blood–brain barrier (BBB) via addition of caffeine to their water supply or by treatment with rivaroxaban, an inhibitor of factor Xa that is associated with thrombin production. Moreover, the prevention of up‐regulation of pKr‐2 expression reduced neurotoxic symptoms, such as hippocampal neurodegeneration and object recognition decline due to neurotoxic inflammatory responses in 5XFAD mice.

Conclusion and Implications

We identified a novel pathological mechanism of AD mediated by abnormal accumulation of pKr‐2, which functions as an important pathogenic factor in the adult brain via blood brain barrier (BBB) breakdown. Thus, pKr‐2 represents a novel target for AD therapeutic strategies and those for related conditions.

Resveratrol attenuates rotenone-induced inflammation and oxidative stress via STAT1 and Nrf2/Keap1/SLC7A11 pathway in a microglia cell line

SCOPE

Resveratrol is abundant in grapes. A protective role for resveratrol in anti-oxidation and anti-inflammatory has been demonstrated. Rotenone is a pesticide, used to make animal models of Parkinson's disease (PD). The aim of our study was to investigate the protective effect of resveratrol on rotenone-induced microglial BV-2 cells and the mechanism.

METHODS

BV-2 cells were pretreated with resveratrol for 1 h and then exposed to rotenone. The level of microglia activation was detected. The Iron content and the production of glutathione, malondialdehyde (MDA), reactive oxygen species(ROS) were detected to reflect the status of oxidative stress. The mRNA levels of interleukin-1β (IL-1β), IL-6 and tumor necrosis factor-α (TNF-α) were measured by qRT-PCR.The expressions of p-STAT1, NF-E2-related factor (Nrf2), Kelch-like ECH-associated protein 1 (Keap1) and SLC7A11 were measured by western blot.

RESULT

Our results showed that resveratrol attenuates microglia activation and M1 polarization in rotenone-induced BV-2 cells. Rotenone induced the production of free iron, ROS and MDA and inhibited the activity of glutathione, while the effects were reserved by resveratrol. Resveratrol also inhibited the induction effect of rotenone on IL-6, IL-1β, and TNF-α. In addition, resveratrol enhanced the protective effect of on rotenone-induced BV-2 cells via the inhibition of STAT1 and Keap1 and the upregulation of Nrf2 and SLC7A11.

CONCLUSION

Resveratrol attenuated rotenone-induced inflammation and oxidative stress in BV-2 cells through enhancing the inhibition of STAT1and Keap1 and the upregulation of Nrf2 and SLC7A11.

Amazon-derived nutraceuticals: Promises to mitigate chronic inflammatory states and neuroinflammation

Nutraceuticals have been the focus of numerous research in recent years and accumulating data support their use for promoting some health benefits. Several nutraceuticals have been widely studied as supplements due to their functional properties ameliorating symptoms associated with neurological disorders, such as oxidative stress and chronic inflammatory states. This seems to be the case of some fruits and seeds from the Amazon Biome consumed since the pre-Columbian period that could have potential beneficial impact on the human nervous system. The beneficial activities of these food sources are possibly related to a large number of bioactive molecules including polyphenols, carotenoids, unsaturated fatty acids, vitamins, and trace elements. In this context, this review compiled the research on six Amazonian fruits and seeds species and some of the major nutraceuticals found in their composition, presenting brief mechanisms related to their protagonist action in improving inflammatory responses and neuroinflammation.

Neuroinflammation in Alzheimer's Disease

Alzheimer’s disease (AD) is a neurodegenerative disease associated with human aging. Ten percent of individuals over 65 years have AD and its prevalence continues to rise with increasing age. There are currently no effective disease modifying treatments for AD, resulting in increasingly large socioeconomic and personal costs. Increasing age is associated with an increase in low-grade chronic inflammation (inflammaging) that may contribute to the neurodegenerative process in AD. Although the exact mechanisms remain unclear, aberrant elevation of reactive oxygen and nitrogen species (RONS) levels from several endogenous and exogenous processes in the brain may not only affect cell signaling, but also trigger cellular senescence, inflammation, and pyroptosis. Moreover, a compromised immune privilege of the brain that allows the infiltration of peripheral immune cells and infectious agents may play a role. Additionally, meta-inflammation as well as gut microbiota dysbiosis may drive the neuroinflammatory process. Considering that inflammatory/immune pathways are dysregulated in parallel with cognitive dysfunction in AD, elucidating the relationship between the central nervous system and the immune system may facilitate the development of a safe and effective therapy for AD. We discuss some current ideas on processes in inflammaging that appear to drive the neurodegenerative process in AD and summarize details on a few immunomodulatory strategies being developed to selectively target the detrimental aspects of neuroinflammation without affecting defense mechanisms against pathogens and tissue damage.

Potential Therapeutic Role of Phytochemicals to Mitigate Mitochondrial Dysfunctions in Alzheimer's Disease

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder characterized by a decline in cognitive function and neuronal damage. Although the precise pathobiology of AD remains elusive, accumulating evidence suggests that mitochondrial dysfunction is one of the underlying causes of AD. Mutations in mitochondrial or nuclear DNA that encode mitochondrial components may cause mitochondrial dysfunction. In particular, the dysfunction of electron transport chain complexes, along with the interactions of mitochondrial pathological proteins are associated with mitochondrial dysfunction in AD. Mitochondrial dysfunction causes an imbalance in the production of reactive oxygen species, leading to oxidative stress (OS) and vice versa. Neuroinflammation is another potential contributory factor that induces mitochondrial dysfunction. Phytochemicals or other natural compounds have the potential to scavenge oxygen free radicals and enhance cellular antioxidant defense systems, thereby protecting against OS-mediated cellular damage. Phytochemicals can also modulate other cellular processes, including autophagy and mitochondrial biogenesis. Therefore, pharmacological intervention via neuroprotective phytochemicals can be a potential strategy to combat mitochondrial dysfunction as well as AD. This review focuses on the role of phytochemicals in mitigating mitochondrial dysfunction in the pathogenesis of AD.

Novel BuChE-IDO1 inhibitors from sertaconazole: Virtual screening, chemical optimization and molecular modeling studies

In our effort towards the identification of novel BuChE-IDO1 dual-targeted inhibitor for the treatment of Alzheimer's disease (AD), sertaconazole was identified through a combination of structure-based virtual screening followed by MM-GBSA rescoring. Preliminary chemical optimization was performed to develop more potent and selective sertaconazole analogues. In consideration of the selectivity and the inhibitory activity against target proteins, compounds 5c and 5d were selected for the next study. Further modification of compound 5c led to the generation of compound 10g with notably improved selectivity towards BuChE versus AChE. The present study provided us with a good starting point to further design potent and selective BuChE-IDO1 inhibitors, which may benefit the treatment of late stage AD.

Signaling mechanisms underlying inhibition of neuroinflammation by resveratrol in neurodegenerative diseases

Neurodegenerative diseases (NDs), including Alzheimer's disease (AD), and Parkinson's disease (PD), are characterized by the progressive loss of the structure and function of neurons and most commonly occur in the elderly population. Microglia are resident macrophages of the central nervous system (CNS). The neuroinflammation caused by excessive microglial activation is closely related to the onset and progression of many NDs. Therefore, inhibiting excessive microglial activation is a potential drug target for controlling neuroinflammation. In recent years, natural products as modulators of microglial polarization have attracted considerable attention in the field of NDs therapy. Furthermore, resveratrol (RES) has been found to have a protective effect in NDs through the inhibition of microglial activation and the regulation of neuroinflammation. In this review, we mainly summarize the therapeutic potential of RES and its various molecular mechanisms in the treatment of NDs through the modulation of microglial activation.