Transcription factor NF-kappaB is activated in primary neurons by amyloid beta peptides and in neurons surrounding early plaques from patients with Alzheimer disease

Astrocytic uptake of posttranslationally modified amyloid-β leads to endolysosomal system disruption and induction of pro-inflammatory signaling

The disruption of astrocytic catabolic processes contributes to the impairment of amyloid-β (Aβ) clearance, neuroinflammatory signaling, and the loss of synaptic contacts in late-onset Alzheimer's disease (AD). While it is known that the posttranslational modifications of Aβ have significant implications on biophysical properties of the peptides, their consequences for clearance impairment are not well understood. It was previously shown that N-terminally pyroglutamylated Aβ3(pE)-42, a significant constituent of amyloid plaques, is efficiently taken up by astrocytes, leading to the release of pro-inflammatory cytokine tumor necrosis factor α and synapse loss. Here we report that Aβ3(pE)-42, but not Aβ1-42, gradually accumulates within the astrocytic endolysosomal system, disrupting this catabolic pathway and inducing the formation of heteromorphous vacuoles. This accumulation alters lysosomal kinetics, lysosome-dependent calcium signaling, and upregulates the lysosomal stress response. These changes correlate with the upregulation of glial fibrillary acidic protein (GFAP) and increased activity of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). Treatment with a lysosomal protease inhibitor, E-64, rescues GFAP upregulation, NF-κB activation, and synapse loss, indicating that abnormal lysosomal protease activity is upstream of pro-inflammatory signaling and related synapse loss. Collectively, our data suggest that Aβ3(pE)-42-induced disruption of the astrocytic endolysosomal system leads to cytoplasmic leakage of lysosomal proteases, promoting pro-inflammatory signaling and synapse loss, hallmarks of AD-pathology.

The emerging role of brain neuroinflammatory responses in Alzheimer's disease

As the most common cause of dementia, Alzheimer's disease (AD) is characterized by neurodegeneration and synaptic loss with an increasing prevalence in the elderly. Increased inflammatory responses triggers brain cells to produce pro-inflammatory cytokines and accelerates the Aβ accumulation, tau protein hyper-phosphorylation leading to neurodegeneration. Therefore, in this paper, we discuss the current understanding of how inflammation affects brain activity to induce AD pathology, the inflammatory biomarkers and possible therapies that combat inflammation for AD.

Rationally Designed Peptoid Inhibitors of Amyloid-β Oligomerization

While plaques comprised of fibrillar Aβ aggregates are hallmarks of Alzheimer's disease, soluble Aβ oligomers present higher neurotoxicity. Thus, one therapeutic approach is to prevent the formation of Aβ oligomers and reduce their associated harmful effects. We have proposed a peptoid mimic of the Aβ hydrophobic KLVFF core as an ideal candidate aggregation inhibitor due to its ability to evade proteolytic degradation via repositioning of the side chain from the α-carbon to the amide nitrogen. This peptoid, JPT1, utilizes chiral sidechains to achieve a helical structure, while C-terminal addition of two phenylalanine residues places aromatic groups on two sides of the helix with spacing designed to facilitate interaction with amyloid β-sheet structure. We have previously shown that JPT1 modulates Aβ fibril formation. Here, we demonstrate that JPT1 also modulates Aβ oligomerization, and we explore the role of the charge on the linker between the KLVFF mimic and the extended aromatic residues. Additionally, we demonstrate that peptoid-induced changes in Aβ oligomerization correlate with attenuation of oligomer-induced nuclear factor-κB activation in SH-SY5Y human neuroblastoma cells. These findings support the therapeutic potential of peptoids to target early stages of Aβ aggregation and impact the associated Aβ-induced cellular response.

The neuroinflammatory role of microglia in Alzheimer's disease and their associated therapeutic targets

INTRODUCTION

Alzheimer's disease (AD), the main cause of dementia, is characterized by synaptic loss and neurodegeneration. Amyloid-β (Aβ) accumulation, hyperphosphorylation of tau protein, and neurofibrillary tangles (NFTs) in the brain are considered to be the initiating factors of AD. However, this hypothesis falls short of explaining many aspects of AD pathogenesis. Recently, there has been mounting evidence that neuroinflammation plays a key role in the pathophysiology of AD and causes neurodegeneration by over-activating microglia and releasing inflammatory mediators.

METHODS

PubMed, Web of Science, EMBASE, and MEDLINE were used for searching and summarizing all the recent publications related to inflammation and its association with Alzheimer's disease.

RESULTS

Our review shows how inflammatory dysregulation influences AD pathology as well as the roles of microglia in neuroinflammation, the possible microglia-associated therapeutic targets, top neuroinflammatory biomarkers, and anti-inflammatory drugs that combat inflammation.

CONCLUSION

In conclusion, microglial inflammatory reactions are important factors in AD pathogenesis and need to be discussed in more detail for promising therapeutic strategies.

Urolithin A improves Alzheimer's disease cognition and restores mitophagy and lysosomal functions

BACKGROUND

Compromised autophagy, including impaired mitophagy and lysosomal function, plays pivotal roles in Alzheimer's disease (AD). Urolithin A (UA) is a gut microbial metabolite of ellagic acid that stimulates mitophagy. The effects of UA's long-term treatment of AD and mechanisms of action are unknown.

METHODS

We addressed these questions in three mouse models of AD with behavioral, electrophysiological, biochemical, and bioinformatic approaches.

RESULTS

Long-term UA treatment significantly improved learning, memory, and olfactory function in different AD transgenic mice. UA also reduced amyloid beta (Aβ) and tau pathologies and enhanced long-term potentiation. UA induced mitophagy via increasing lysosomal functions. UA improved cellular lysosomal function and normalized lysosomal cathepsins, primarily cathepsin Z, to restore lysosomal function in AD, indicating the critical role of cathepsins in UA-induced therapeutic effects on AD.

CONCLUSIONS

Our study highlights the importance of lysosomal dysfunction in AD etiology and points to the high translational potential of UA.

HIGHLIGHTS

Long-term urolithin A (UA) treatment improved learning, memory, and olfactory function in Alzheimer's disease (AD) mice. UA restored lysosomal functions in part by regulating cathepsin Z (Ctsz) protein. UA modulates immune responses and AD-specific pathophysiological pathways.

Edaravone Dexborneol mitigates pathology in animal and cell culture models of Alzheimer's disease by inhibiting neuroinflammation and neuronal necroptosis

BACKGROUND

Alzheimer's disease (AD) is the most prevalent neurodegenerative disease with limited disease-modifying treatments. Drug repositioning strategy has now emerged as a promising approach for anti-AD drug discovery. Using 5×FAD mice and Aβ-treated neurons in culture, we tested the efficacy of Y-2, a compounded drug containing the antioxidant Edaravone (Eda), a pyrazolone and (+)-Borneol, an anti-inflammatory diterpenoid from cinnamon, approved for use in amyotrophic lateral sclerosis patients.

RESULTS

We examined effects of Y-2 versus Eda alone by i.p. administered in 8-week-old 5×FAD mice (females) for 4 months by comparing cognitive function, Aβ pathologies, neuronal necroptosis and neuroinflammation. Using primary neurons and astrocytes, as well as neuronal and astrocytic cell lines, we elucidated the molecular mechanisms of Y-2 by examining neuronal injury, astrocyte-mediated inflammation and necroptosis. Here, we find that Y-2 improves cognitive function in AD mice. Histopathological data show that Y-2, better than Eda alone, markedly ameliorates Aβ pathologies including Aβ burden, astrogliosis/microgliosis, and Tau phosphorylation. In addition, Y-2 reduces Aβ-induced neuronal injury including neurite damage, mitochondrial impairment, reactive oxygen species production and NAD+ depletion. Notably, Y-2 inhibits astrocyte-mediated neuroinflammation and attenuates TNF-α-triggered neuronal necroptosis in cell cultures and AD mice. RNA-seq further demonstrates that Y-2, compared to Eda, indeed upregulates anti-inflammation pathways in astrocytes.

CONCLUSIONS

Our findings infer that Y-2, better than Eda alone, mitigates AD pathology and may provide a potential drug candidate for AD treatment.

Anti-Neuroinflammatory Effects of a Macrocyclic Peptide-Peptoid Hybrid in Lipopolysaccharide-Stimulated BV2 Microglial Cells

Inflammation processes of the central nervous system (CNS) play a vital role in the pathogenesis of several neurological and psychiatric disorders like depression. These processes are characterized by the activation of glia cells, such as microglia. Clinical studies showed a decrease in symptoms associated with the mentioned diseases after the treatment with anti-inflammatory drugs. Therefore, the investigation of novel anti-inflammatory drugs could hold substantial potential in the treatment of disorders with a neuroinflammatory background. In this in vitro study, we report the anti-inflammatory effects of a novel hexacyclic peptide-peptoid hybrid in lipopolysaccharide (LPS)-stimulated BV2 microglial cells. The macrocyclic compound X15856 significantly suppressed Interleukin 6 (IL-6), tumor necrosis factor-α (TNF-α), c-c motif chemokine ligand 2 (CCL2), CCL3, C-X-C motif chemokine ligand 2 (CXCL2), and CXCL10 expression and release in LPS-treated BV2 microglial cells. The anti-inflammatory effects of the compound are partially explained by the modulation of the phosphorylation of p38 mitogen-activated protein kinases (MAPK), p42/44 MAPK (ERK 1/2), protein kinase C (PKC), and the nuclear factor (NF)-κB, respectively. Due to its remarkable anti-inflammatory properties, this compound emerges as an encouraging option for additional research and potential utilization in disorders influenced by inflammation, such as depression.

NF-κB as an Inducible Regulator of Inflammation in the Central Nervous System

The NF-κB (nuclear factor K-light-chain-enhancer of activated B cells) transcription factor family is critical for modulating the immune proinflammatory response throughout the body. During the resting state, inactive NF-κB is sequestered by IκB in the cytoplasm. The proteasomal degradation of IκB activates NF-κB, mediating its translocation into the nucleus to act as a nuclear transcription factor in the upregulation of proinflammatory genes. Stimuli that initiate NF-κB activation are diverse but are canonically attributed to proinflammatory cytokines and chemokines. Downstream effects of NF-κB are cell type-specific and, in the majority of cases, result in the activation of pro-inflammatory cascades. Acting as the primary immune responders of the central nervous system, microglia exhibit upregulation of NF-κB upon activation in response to pathological conditions. Under such circumstances, microglial crosstalk with other cell types in the central nervous system can induce cell death, further exacerbating the disease pathology. In this review, we will emphasize the role of NF-κB in triggering neuroinflammation mediated by microglia.

Inflammasome signaling is dispensable for ß-amyloid-induced neuropathology in preclinical models of Alzheimer's disease

Background

Alzheimer's disease (AD) is the most common neurodegenerative disorder affecting memory and cognition. The disease is accompanied by an abnormal deposition of ß-amyloid plaques in the brain that contributes to neurodegeneration and is known to induce glial inflammation. Studies in the APP/PS1 mouse model of ß-amyloid-induced neuropathology have suggested a role for inflammasome activation in ß-amyloid-induced neuroinflammation and neuropathology.

Methods

Here, we evaluated the in vivo role of microglia-selective and full body inflammasome signalling in several mouse models of ß-amyloid-induced AD neuropathology.

Results

Microglia-specific deletion of the inflammasome regulator A20 and inflammasome effector protease caspase-1 in the AppNL-G-F and APP/PS1 models failed to identify a prominent role for microglial inflammasome signalling in ß-amyloid-induced neuropathology. Moreover, global inflammasome inactivation through respectively full body deletion of caspases 1 and 11 in AppNL-G-F mice and Nlrp3 deletion in APP/PS1 mice also failed to modulate amyloid pathology and disease progression. In agreement, single-cell RNA sequencing did not reveal an important role for Nlrp3 signalling in driving microglial activation and the transition into disease-associated states, both during homeostasis and upon amyloid pathology.

Conclusion

Collectively, these results question a generalizable role for inflammasome activation in preclinical amyloid-only models of neuroinflammation.

It's a TRIM-endous view from the top: the varied roles of TRIpartite Motif proteins in brain development and disease

The tripartite motif (TRIM) protein family members have been implicated in a multitude of physiologies and pathologies in different tissues. With diverse functions in cellular processes including regulation of signaling pathways, protein degradation, and transcriptional control, the impact of TRIM dysregulation can be multifaceted and complex. Here, we focus on the cellular and molecular roles of TRIMs identified in the brain in the context of a selection of pathologies including cancer and neurodegeneration. By examining each disease in parallel with described roles in brain development, we aim to highlight fundamental common mechanisms employed by TRIM proteins and identify opportunities for therapeutic intervention.

The link between metabolic syndrome and Alzheimer disease: A mutual relationship and long rigorous investigation

It has been illustrated that metabolic syndrome (MetS) is associated with Alzheimer disease (AD) neuropathology. Components of MetS including central obesity, hypertension, insulin resistance (IR), and dyslipidemia adversely affect the pathogenesis of AD by different mechanisms including activation of renin-angiotensin system (RAS), inflammatory signaling pathways, neuroinflammation, brain IR, mitochondrial dysfunction, and oxidative stress. MetS exacerbates AD neuropathology, and targeting of molecular pathways in MetS by pharmacological approach could a novel therapeutic strategy in the management of AD in high risk group. However, the underlying mechanisms of these pathways in AD neuropathology are not completely clarified. Therefore, this review aims to elucidate the association between MetS and AD regarding the oxidative and inflammatory mechanistic pathways.

Gut microbiota-derived short chain fatty acids act as mediators of the gut-brain axis targeting age-related neurodegenerative disorders: a narrative review

Neurodegenerative diseases associated with aging are often accompanied by cognitive decline and gut microbiota disorder. But the impact of gut microbiota on these cognitive disturbances remains incompletely understood. Short chain fatty acids (SCFAs) are major metabolites produced by gut microbiota during the digestion of dietary fiber, serving as an energy source for gut epithelial cells and/or circulating to other organs, such as the liver and brain, through the bloodstream. SCFAs have been shown to cross the blood-brain barrier and played crucial roles in brain metabolism, with potential implications in mediating Alzheimer's disease (AD) and Parkinson's disease (PD). However, the underlying mechanisms that SCFAs might influence psychological functioning, including affective and cognitive processes and their neural basis, have not been fully elucidated. Furthermore, the dietary sources which determine these SCFAs production was not thoroughly evaluated yet. This comprehensive review explores the production of SCFAs by gut microbiota, their transportation through the gut-brain axis, and the potential mechanisms by which they influence age-related neurodegenerative disorders. Also, the review discusses the importance of dietary fiber sources and the challenges associated with harnessing dietary-derived SCFAs as promoters of neurological health in elderly individuals. Overall, this study suggests that gut microbiota-derived SCFAs and/or dietary fibers hold promise as potential targets and strategies for addressing age-related neurodegenerative disorders.

Biochemical and Molecular Pathways in Neurodegenerative Diseases: An Integrated View

Neurodegenerative diseases (NDDs) like Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS) are defined by a myriad of complex aetiologies. Understanding the common biochemical molecular pathologies among NDDs gives an opportunity to decipher the overlapping and numerous cross-talk mechanisms of neurodegeneration. Numerous interrelated pathways lead to the progression of neurodegeneration. We present evidence from the past pieces of literature for the most usual global convergent hallmarks like ageing, oxidative stress, excitotoxicity-induced calcium butterfly effect, defective proteostasis including chaperones, autophagy, mitophagy, and proteosome networks, and neuroinflammation. Herein, we applied a holistic approach to identify and represent the shared mechanism across NDDs. Further, we believe that this approach could be helpful in identifying key modulators across NDDs, with a particular focus on AD, PD, and ALS. Moreover, these concepts could be applied to the development and diagnosis of novel strategies for diverse NDDs.

GPR34 Knockdown Relieves Cognitive Deficits and Suppresses Neuroinflammation in Alzheimer's Disease via the ERK/NF-κB Signal

Alzheimer's disease (AD) is a serious neurodegenerative disease characterized by amyloid-β (Aβ) aggregation and neuroinflammation. G-protein-coupled receptor 34 (Gpr34) was found highly expressed in the hippocampus of APP/PS1 mice. However, its role in AD remains unclear. Herein, the role of Gpr34 as well as its molecular mechanism was explored. Data in GSE85162 were analyzed and the differently expressed genes in the hippocampus tissues of APP/PS1 mouse model of AD were subjected to GO, KEGG and GSEA enrichment analyses. APP/PS1 mice were used as an animal model of AD and the cognitive impairment was evaluated by a water maze test. The level of Gpr34 in hippocampus and BV-2 cells as well as the activation of ERK/NF-κB signal was determined by quantitative real-time PCR, western blot or immunofluorescence. Our results showed that, in BV-2 cells exposed to Aβ1-42, Gpr34 knockdown decreased the levels of TNF-α, IL-1β, IL-6 and iNOS and suppressed the activation of ERK/NF-κB signal. Moreover, the Gpr34-overexpression-induced activation of ERK/NF-κB signal and up-regulated levels of TNF-α, IL-1β, IL-6 and iNOS were abolished by FR180204, an ERK inhibitor. On the other hand, the in vivo study showed that Gpr34 knockdown ameliorated the cognitive impairment in APP/PS1 mice, decreased the levels of TNF-α, IL-1β and IL-6, the activation of microglia and ERK/NF-κB signal. In conclusion, Gpr34 knockdown relieved cognitive deficits in APP/PS1 mice and suppressed neuroinflammation and microglial activation, maybe via the ERK/NF-κB signal. It is indicated that the high level of Grp34 in hippocampus may contribute to the pathogenesis of AD.

Multi-target regulatory mechanism of Yang Xin Tang - a traditional Chinese medicine against dementia

BACKGROUND

Yang Xin Tang (YXT) is a traditional Chinese herbal preparation which has been reported to improve cognitive function and memory in patients with dementia. As the underlying mechanism of action of YXT has not been elucidated, we examined the effects of YXT and its major herbal components in regulating gene transcription and molecular targets related to Alzheimer's disease (AD).

METHODS

Aqueous and ethanol extracts of YXT and selected herbal components were prepared and validated by standard methods. A series of biochemical and cellular assays were employed to assess the ability of the herbal extracts to inhibit acetylcholinesterase, reduce β-amyloid aggregation, stimulate the differentiation of neural progenitor cells, suppress cyclooxygenase, and protect neurons against β-amyloid or N-methyl-D-aspartate-induced cytotoxicity. The effects of YXT on multiple molecular targets were further corroborated by a panel of nine reporter gene assays.

RESULTS

Extracts of YXT and two of its constituent herbs, Poria cocos and Poria Sclerotium pararadicis, significantly inhibited β-amyloid aggregation and β-amyloid-induced cytotoxicity. A protective effect of the YXT extract was similarly observed against N-methyl-D-aspartate-induced cytotoxicity in primary neurons, and this activity was shared by extracts of Radix Astragali and Rhizoma Chuanxiong. Although the YXT extract was ineffective, extracts of Poria cocos, Poria Sclerotium pararadicis and Radix Polygalae inhibited acetylcholine esterase, with the latter also capable of upregulating choline acetyltransferase. YXT and its components significantly inhibited the activities of the pro-inflammatory cyclooxygenases. Additionally, extracts of YXT and several of its constituent herbs significantly stimulated the phosphorylation of extracellular signal-regulated kinases and cAMP-responsive element binding protein, two molecular targets involved in learning and memory, as well as in the regulation of neurogenesis.

CONCLUSIONS

Several constituents of YXT possess multiple regulatory effects on known therapeutic targets of AD that range from β-amyloid to acetylcholinesterase. The demonstrated neuroprotective and neurogenic actions of YXT lend credence to its use as an alternative medicine for treating AD.

Astrocyte-targeting therapy rescues cognitive impairment caused by neuroinflammation via the Nrf2 pathway

Neuroinflammation is a common feature of neurodegenerative disorders such as Alzheimer's disease (AD). Neuroinflammation is induced by dysregulated glial activation, and astrocytes, the most abundant glial cells, become reactive upon neuroinflammatory cytokines released from microglia and actively contribute to neuronal loss. Therefore, blocking reactive astrocyte functions is a viable strategy to manage neurodegenerative disorders. However, factors or therapeutics directly regulating astrocyte subtypes remain unexplored. Here, we identified transcription factor NF-E2-related factor 2 (Nrf2) as a therapeutic target in neurotoxic reactive astrocytes upon neuroinflammation. We found that the absence of Nrf2 promoted the activation of reactive astrocytes in the brain tissue samples obtained from AD model 5xFAD mice, whereas enhanced Nrf2 expression blocked the induction of reactive astrocyte gene expression by counteracting NF-κB subunit p65 recruitment. Neuroinflammatory astrocytes robustly up-regulated genes associated with type I interferon and the antigen-presenting pathway, which were suppressed by Nrf2 pathway activation. Moreover, impaired cognitive behaviors observed in AD mice were rescued upon ALGERNON2 treatment, which potentiated the Nrf2 pathway and reduced the induction of neurotoxic reactive astrocytes. Thus, we highlight the potential of astrocyte-targeting therapy by promoting the Nrf2 pathway signaling for neuroinflammation-triggered neurodegeneration.

Classification and deep-learning-based prediction of Alzheimer disease subtypes by using genomic data

Late-onset Alzheimer's disease (LOAD) is the most common multifactorial neurodegenerative disease among elderly people. LOAD is heterogeneous, and the symptoms vary among patients. Genome-wide association studies (GWAS) have identified genetic risk factors for LOAD but not for LOAD subtypes. Here, we examined the genetic architecture of LOAD based on Japanese GWAS data from 1947 patients and 2192 cognitively normal controls in a discovery cohort and 847 patients and 2298 controls in an independent validation cohort. Two distinct groups of LOAD patients were identified. One was characterized by major risk genes for developing LOAD (APOC1 and APOC1P1) and immune-related genes (RELB and CBLC). The other was characterized by genes associated with kidney disorders (AXDND1, FBP1, and MIR2278). Subsequent analysis of albumin and hemoglobin values from routine blood test results suggested that impaired kidney function could lead to LOAD pathogenesis. We developed a prediction model for LOAD subtypes using a deep neural network, which achieved an accuracy of 0.694 (2870/4137) in the discovery cohort and 0.687 (2162/3145) in the validation cohort. These findings provide new insights into the pathogenic mechanisms of LOAD.

Soluble and insoluble protein aggregates, endoplasmic reticulum stress, and vascular dysfunction in Alzheimer's disease and cardiovascular diseases

Dementia refers to a particular group of symptoms characterized by difficulties with memory, language, problem-solving, and other thinking skills that affect a person's ability to perform everyday activities. Alzheimer's disease (AD) is the most common form of dementia, affecting about 6.2 million Americans aged 65 years and older. Likewise, cardiovascular diseases (CVDs) are a major cause of disability and premature death, impacting 126.9 million adults in the USA, a number that increases with age. Consequently, CVDs and cardiovascular risk factors are associated with an increased risk of AD and cognitive impairment. They share important age-related cardiometabolic and lifestyle risk factors, that make them among the leading causes of death. Additionally, there are several premises and hypotheses about the mechanisms underlying the association between AD and CVD. Although AD and CVD may be considered deleterious to health, the study of their combination constitutes a clinical challenge, and investigations to understand the mechanistic pathways for the cause-effect and/or shared pathology between these two disease constellations remains an active area of research. AD pathology is propagated by the amyloid β (Aβ) peptides. These peptides give rise to small, toxic, and soluble Aβ oligomers (SPOs) that are nonfibrillar, and it is their levels that show a robust correlation with the extent of cognitive impairment. This review will elucidate the interplay between the effects of accumulating SPOs in AD and CVDs, the resulting ER stress response, and their role in vascular dysfunction. We will also address the potential underlying mechanisms, including the possibility that SPOs are among the causes of vascular injury in CVD associated with cognitive decline. By revealing common mechanistic underpinnings of AD and CVD, we hope that novel experimental therapeutics can be designed to reduce the burden of these devastating diseases. Graphical abstract Alzheimer's disease (AD) pathology leads to the release of Aβ peptides, and their accumulation in the peripheral organs has varying effects on various components of the cardiovascular system including endoplasmic reticulum (ER) stress and vascular damage. Image created with BioRender.com.

TXNIP contributes to induction of pro-inflammatory phenotype and caspase-3 activation in astrocytes during Alzheimer's diseases

Neuroinflammation and oxidative stress have been implicated in the pathogenesis of Alzheimer's disease (AD). Neuroinflammation and oxidative stress are associated with neuronal death in AD. Astrocytes are linked to neuroinflammation during AD. Astrocytes are important contributors to AD progression. Although the role of thioredoxin-interacting protein (TXNIP) has been identified in inflammation and oxidative stress, the mechanism by which TXNIP regulates inflammation and oxidative stress in astrocytes during AD remains unclear. In the present study, we found that TXNIP gene levels were elevated in cerebral cortex of patients with AD. The protein levels of TXNIP were elevated in GFAP-positive astrocytes of cerebral cortex from patients with AD and APP/PS1 double-transgenic mouse model of AD. Our results showed that TXNIP increased expression of genes related to pro-inflammatory reactive astrocytes and pro-inflammatory cytokines and chemokines in human astrocytes. Moreover, TXNIP increased production of pro-inflammatory cytokines and chemokines in human astrocytes. TXNIP induced activation of NK-kB signaling and over-production of mitochondrial reactive oxygen species (mtROS) in human astrocytes. TXNIP also induced mitochondrial oxidative stress by reduction of mitochondrial respiration and ATP production in human astrocytes. Furthermore, elevated TXNIP levels are correlated with caspase-3 activation of GFAP-positive astrocytes in patients with AD and mouse AD. TXNIP induced mitochondria-dependent apoptosis via caspase-9 and caspase-3 activation in human astrocytes. These results suggest that TXNIP contributes to induction of pro-inflammatory phenotype and caspase-3 activation in astrocytes during AD.

TRAPPC9-related neurodevelopmental disorder: Report of a homozygous deletion in TRAPPC9 due to paternal uniparental isodisomy

TRAPPC9 loss-of-function biallelic variants are associated with an autosomal recessive intellectual disability syndrome (Online Mendelian Inheritance of Man no. 613192), also characterized by microcephaly, hypertelorism, obesity, growth delay, and behavioral differences. Here, we describe an 8-year-old Hispanic female with neurodevelopmental disorder, partial epilepsy, microcephaly, bilateral cleft lip and alveolus, growth delay, and dysmorphic features. She had abnormal myelination, mega cisterna magna, and colpocephaly on brain magnetic resonance imaging (MRI). Microarray showed a single ~146 Mb region of homozygosity (ROH) encompassing all of Chromosome 8, consistent with uniparental isodisomy (UPD). Exome sequencing performed in-house did not identify single nucleotide variants to explain her phenotype. Algorithms developed in-house and further evaluation of BAM files revealed a homozygous deletion overlapping Exon 2 in TRAPPC9 within the ROH. Subsequent del/dup analyses with exon-level oligo array confirmed a likely pathogenic deletion in TRAPPC9 (NM_031466.5): arr[GRCh37] 8q24.3(141460661_141461780)x0. Our case highlights the implications of downstream analyses from UPD/ROH given the increased risk for AR conditions, the strengths of combining orthologous molecular methods to establish a diagnosis and further delineates the TRAPPC9-related phenotype in an individual of Hispanic ancestry.

EPO regulates neuronal differentiation of adult human neural-crest derived stem cells in a sex-specific manner

BACKGROUND

Sexual differences in the biology of human stem cells are increasingly recognized to influence their proliferation, differentiation and maturation. Especially in neurodegenerative diseases such as Alzheimers disease (AD), Parkinson's disease (PD) or ischemic stroke, sex is a key player for disease progression and recovery of damaged tissue. Recently, the glycoprotein hormone erythropoietin (EPO) has been implicated as a regulator of neuronal differentiation and maturation in female rats.

METHODS

In this study, we used adult human neural crest-derived stem cells (NCSCs) as a model system for exploring potential sex specific effects of EPO on human neuronal differentiation. We started with expression validation of the specific EPO receptor (EPOR) by performing PCR analysis in the NCSCs. Next, EPO mediated activation of nuclear factor-κB (NF-κB) via Immunocytochemistry (ICC) was performed, followed by investigating the sex-specific effects of EPO on neuronal differentiation by determining morphological changes in axonal growth and neurite formation accompanied by ICC.

RESULTS

Undifferentiated male and female NCSCs showed a ubiquitous expression of the EPO receptor (EPOR). EPO treatment resulted in a statistically profound (male p = 0.0022, female p = 0.0012) nuclear translocation of NF-κB RELA in undifferentiated NCSCs of both sexes. But after one week of neuronal differentiation, we could show a highly significant (p = 0,0079) increase of nuclear NF-κB RELA in females only. In contrast, we observed a strong decrease (p = 0,0022) of RELA activation in male neuronal progenitors. Extending the view on the role of sex during human neuronal differentiation, here we demonstrate a significant increase of axon lengths in female NCSCs-derived neurons upon EPO-treatment (+ EPO: 167,73 (SD = 41,66) µm, w/o EPO: 77,68 (SD = 18,31) µm) compared to their male counterparts (+ EPO: 68,37 (SD = 11,97) µm, w/o EPO: 70,23 (SD = 12,89) µm).

CONCLUSION

Our present findings therefore show for the first time an EPO-driven sexual dimorphism in neuronal differentiation of human neural-crest derived stem cells and emphasize sex-specific variability as a crucial parameter in stem cell biology and for treating neurodegenerative diseases.

The Interaction Between NF-κB and Estrogen in Alzheimer's Disease

Post-menopausal women are at a higher risk of developing Alzheimer's disease (AD) than males. The higher rates of AD in women are associated with the sharp decline in the estrogen levels after menopause. Estrogen has been shown to downregulate inflammatory cytokines in the central nervous system (CNS), which has a neuroprotective role against neurodegenerative diseases including AD. Sustained neuroinflammation is associated with neurodegeneration and contributes to AD. Nuclear factor kappa-B (NF-κB) is a transcription factor involved with the modulation of inflammation and interacts with estrogen to influence the progression of AD. Application of 17β-estradiol (E2) has been shown to inhibit NF-κB, thereby reducing transcription of NF-κB target genes. Despite accumulating evidence showing that estrogens have beneficial effects in pre-clinical AD studies, there are mixed results with hormone replacement therapy in clinical trials. Furthering our understanding of how NF-κB interacts with estrogen and alters the progression of neurodegenerative disorders including AD, should be beneficial and result in the development of novel therapeutics.

Deficiency of IKKβ in neurons ameliorates Alzheimer's disease pathology in APP- and tau-transgenic mice

In Alzheimer's disease (AD) brain, inflammatory activation regulates protein levels of amyloid-β-peptide (Aβ) and phosphorylated tau (p-tau), as well as neurodegeneration; however, the regulatory mechanisms remain unclear. We constructed APP- and tau-transgenic AD mice with deletion of IKKβ specifically in neurons, and observed that IKKβ deficiency reduced cerebral Aβ and p-tau, and modified inflammatory activation in both AD mice. However, neuronal deficiency of IKKβ decreased apoptosis and maintained synaptic proteins (e.g., PSD-95 and Munc18-1) in the brain and improved cognitive function only in APP-transgenic mice, but not in tau-transgenic mice. Additionally, IKKβ deficiency decreased BACE1 protein and activity in APP-transgenic mouse brain and cultured SH-SY5Y cells. IKKβ deficiency increased expression of PP2A catalytic subunit isoform A, an enzyme dephosphorylating cerebral p-tau, in the brain of tau-transgenic mice. Interestingly, deficiency of IKKβ in neurons enhanced autophagy as indicated by the increased ratio of LC3B-II/I in brains of both APP- and tau-transgenic mice. Thus, IKKβ deficiency in neurons ameliorates AD-associated pathology in APP- and tau-transgenic mice, perhaps by decreasing Aβ production, increasing p-tau dephosphorylation, and promoting autophagy-mediated degradation of BACE1 and p-tau aggregates in the brain. However, IKKβ deficiency differently protects neurons in APP- and tau-transgenic mice. Further studies are needed, particularly in the context of interaction between Aβ and p-tau, before IKKβ/NF-κB can be targeted for AD therapies.

The Phospholipase A2 Superfamily: Structure, Isozymes, Catalysis, Physiologic and Pathologic Roles

The phospholipase A2 (PLA2) superfamily of phospholipase enzymes hydrolyzes the ester bond at the sn-2 position of the phospholipids, generating a free fatty acid and a lysophospholipid. The PLA2s are amphiphilic in nature and work only at the water/lipid interface, acting on phospholipid assemblies rather than on isolated single phospholipids. The superfamily of PLA2 comprises at least six big families of isoenzymes, based on their structure, location, substrate specificity and physiologic roles. We are reviewing the secreted PLA2 (sPLA2), cytosolic PLA2 (cPLA2), Ca²⁺-independent PLA2 (iPLA2), lipoprotein-associated PLA2 (LpPLA2), lysosomal PLA2 (LPLA2) and adipose-tissue-specific PLA2 (AdPLA2), focusing on the differences in their structure, mechanism of action, substrate specificity, interfacial kinetics and tissue distribution. The PLA2s play important roles both physiologically and pathologically, with their expression increasing significantly in diseases such as sepsis, inflammation, different cancers, glaucoma, obesity and Alzheimer's disease, which are also detailed in this review.

Inflammation context in Alzheimer's disease, a relationship intricate to define

Alzheimer's disease (AD), the most common form of dementia, is characterized by the accumulation of amyloid β (Aβ) and hyperphosphorylated tau protein aggregates. Importantly, Aβ and tau species are able to activate astrocytes and microglia, which release several proinflammatory cytokines, such as tumor necrosis factor α (TNF-α) and interleukin 1β (IL-1β), together with reactive oxygen (ROS) and nitrogen species (RNS), triggering neuroinflammation. However, this inflammatory response has a dual function: it can play a protective role by increasing Aβ degradation and clearance, but it can also contribute to Aβ and tau overproduction and induce neurodegeneration and synaptic loss. Due to the significant role of inflammation in the pathogenesis of AD, several inflammatory mediators have been proposed as AD markers, such as TNF-α, IL-1β, Iba-1, GFAP, NF-κB, TLR2, and MHCII. Importantly, the use of anti-inflammatory drugs such as NSAIDs has emerged as a potential treatment against AD. Moreover, diseases related to systemic or local inflammation, including infections, cerebrovascular accidents, and obesity, have been proposed as risk factors for the development of AD. In the following review, we focus on key inflammatory processes associated with AD pathogenesis.

Emerging roles of innate and adaptive immunity in Alzheimer's disease

Alzheimer's disease (AD) is the most common neurodegenerative disease, with characteristic extracellular amyloid-β (Aβ) deposition and intracellular accumulation of hyperphosphorylated, aggregated tau. Several key regulators of innate immune pathways are genetic risk factors for AD. While these genetic risk factors as well as in vivo data point to key roles for microglia, emerging evidence also points to a role of the adaptive immune response in disease pathogenesis. We review the roles of innate and adaptive immunity, their niches, their communication, and their contributions to AD development and progression. We also summarize the cellular compositions and physiological functions of immune cells in the parenchyma, together with those in the brain border structures that form a dynamic disease-related immune niche. We propose that both innate and adaptive immune responses in brain parenchyma and border structures could serve as important therapeutic targets for treating both the pre-symptomatic and the symptomatic stages of AD.

Pomegranate (Punica granatum L.) Attenuates Neuroinflammation Involved in Neurodegenerative Diseases

Food scientists have studied the many health benefits of polyphenols against pernicious human diseases. Evidence from scientific studies has shown that earlier healthy lifestyle changes, particularly in nutrition patterns, can reduce the burden of age-related diseases. In this context, a large number of plant-derived components belonging to the class of polyphenols have been reported to possess neuroprotective benefits. In this review, we examined studies on the effect of dietary polyphenols, notably from Punica granatum L., on neurodegenerative disease, including Alzheimer's disease, which is symptomatically characterized by impairment of cognitive functions. Clinical trials are in favor of the role of some polyphenols in maintaining neuronal homeostasis and attenuating clinical presentations of the disease. However, discrepancies in study design often bring inconsistent findings on the same component and display differences in their effectiveness due to interindividual variability, bioavailability in the body after administration, molecular structures, cross-blood-brain barrier, and signaling pathways such as nuclear factor kappa B (NF-κB). Based on preclinical and clinical trials, it appears that pomegranate may prove valuable in treating neurodegenerative disorders, including Alzheimer's disease (AD) and Parkinson's disease (PD). Therefore, due to the lack of information on human clinical trials, future in-depth studies, focusing on human beings, of several bioactive components of pomegranate's polyphenols and their synergic effects should be carried out to evaluate their curative treatment.

Anti-Inflammatory Activity of 4-(4-(Heptyloxy)phenyl)-2,4-dihydro-3H-1,2,4-triazol-3-one via Repression of MAPK/NF-κB Signaling Pathways in β-Amyloid-Induced Alzheimer's Disease Models

Alzheimer’s disease (AD) is a major neurodegenerative disease, but so far, it can only be treated symptomatically rather than changing the process of the disease. Recently, triazoles and their derivatives have been shown to have potential for the treatment of AD. In this study, the neuroprotective effects of 4-(4-(heptyloxy)phenyl)-2,4-dihydro-3H-1,2,4-triazol-3-one (W112) against β-amyloid (Aβ)-induced AD pathology and its possible mechanism were explored both in vitro and in vivo. The results showed that W112 exhibits a neuroprotective role against Aβ-induced cytotoxicity in PC12 cells and improves the learning and memory abilities of Aβ-induced AD-like rats. In addition, the assays of the protein expression revealed that W112 reversed tau hyperphosphorylation and reduced the production of proinflammatory cytokines, tumor necrosis factor-α and interleukin-6, both in vitro and in vivo studies. Further study indicated that the regulation of mitogen-activated protein kinase/nuclear factor-κB pathways played a key role in mediating the neuroprotective effects of W112 against AD-like pathology. W112 may become a potential drug for AD intervention.

NF-κB in neurodegenerative diseases: Recent evidence from human genetics

The transcription factor NF-κB is commonly known to drive inflammation and cancer progression, but is also a crucial regulator of a broad range of cellular processes within the mammalian nervous system. In the present review, we provide an overview on the role of NF-κB in the nervous system particularly including its constitutive activity within cortical and hippocampal regions, neuroprotection as well as learning and memory. Our discussion further emphasizes the increasing role of human genetics in neurodegenerative disorders, namely, germline mutations leading to defects in NF-κB-signaling. In particular, we propose that loss of function mutations upstream of NF-κB such as ADAM17, SHARPIN, HOIL, or OTULIN affect NF-κB-activity in Alzheimer’s disease (AD) patients, in turn driving anatomical defects such as shrinkage of entorhinal cortex and the limbic system in early AD. Similarly, E3 type ubiquitin ligase PARKIN is positively involved in NF-κB signaling. PARKIN loss of function mutations are most frequently observed in Parkinson’s disease patients. In contrast to AD, relying on germline mutations of week alleles and a disease development over decades, somatic mutations affecting NF-κB activation are commonly observed in cells derived from glioblastoma multiforme (GBM), the most common malignant primary brain tumor. Here, our present review particularly sheds light on the mutual exclusion of either the deletion of NFKBIA or amplification of epidermal growth factor receptor (EGFR) in GBM, both resulting in constitutive NF-κB-activity driving tumorigenesis. We also discuss emerging roles of long non-coding RNAs such as HOTAIR in suppressing phosphorylation of IκBα in the context of GBM. In summary, the recent progress in the genetic analysis of patients, particularly those suffering from AD, harbors the potential to open up new vistas for research and therapy based on TNFα/NF-κB pathway and neuroprotection.

Microglial NF-κB drives tau spreading and toxicity in a mouse model of tauopathy

Activation of microglia is a prominent pathological feature in tauopathies, including Alzheimer's disease. How microglia activation contributes to tau toxicity remains largely unknown. Here we show that nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling, activated by tau, drives microglial-mediated tau propagation and toxicity. Constitutive activation of microglial NF-κB exacerbated, while inactivation diminished, tau seeding and spreading in young PS19 mice. Inhibition of NF-κB activation enhanced the retention while reduced the release of internalized pathogenic tau fibrils from primary microglia and rescued microglial autophagy deficits. Inhibition of microglial NF-κB in aged PS19 mice rescued tau-mediated learning and memory deficits, restored overall transcriptomic changes while increasing neuronal tau inclusions. Single cell RNA-seq revealed that tau-associated disease states in microglia were diminished by NF-κB inactivation and further transformed by constitutive NF-κB activation. Our study establishes a role for microglial NF-κB signaling in mediating tau spreading and toxicity in tauopathy.

Oleuropein-Rich Olive Leaf Extract Attenuates Neuroinflammation in the Alzheimer's Disease Mouse Model

Alzheimer's disease (AD) is the most common form of dementia among several neurodegenerative disorders afflicting the elderly. AD is characterized by the deposition of extracellular amyloid-β (Aβ) plaques, disrupted blood-brain barrier (BBB), and neuroinflammation. Several studies have demonstrated the health benefits of olive oil and olive leaf extract (OLE) due to their polyphenolic content. The main phenolic compound in OLE is glycosylated oleuropein (OLG), while the aglycon form of oleuropein (OLA) exists in much lower amounts. This work aimed to evaluate the effect of a low dose of OLG-rich OLE and the mechanism(s) that contributed to the observed beneficial effects against Aβ pathology in the homozygous 5xFAD mouse model. Mice were fed with OLE-enriched diet (695 μg/kg body weight/day) for 3 months, starting at 3 months old. Overall findings demonstrated that OLE reduced neuroinflammation by inhibiting the NF-κB pathway and suppressing the activation of NLRP3 inflammasomes and RAGE/HMGB1 pathways. In addition, OLE reduced total Aβ brain levels due to increased clearance and reduced production of Aβ and enhanced BBB integrity and function, which collectively improved the memory function. Thus, the consumption of OLE as a dietary supplement is expected to stop and/or slow the progression of AD.

Neuroprotective Effects of Green Tea Seed Isolated Saponin Due to the Amelioration of Tauopathy and Alleviation of Neuroinflammation: A Therapeutic Approach to Alzheimer's Disease

Tauopathy is one of the major causes of neurodegenerative disorders and diseases such as Alzheimer’s disease (AD). Hyperphosphorylation of tau proteins by various kinases leads to the formation of PHF and NFT and eventually results in tauopathy and AD; similarly, neuroinflammation also exaggerates and accelerates neuropathy and neurodegeneration. Natural products with anti-tauopathy and anti-neuroinflammatory effects are highly recommended as safe and feasible ways of preventing and /or treating neurodegenerative diseases, including AD. In the present study, we isolated theasaponin E1 from ethanol extract of green tea seed and evaluated its therapeutic inhibitory effects on tau hyper-phosphorylation and neuroinflammation in neuroblastoma (SHY-5Y) and glioblastoma (HTB2) cells, respectively, to elucidate the mechanism of the inhibitory effects. The expression of tau-generating and phosphorylation-promoting genes under the effects of theasaponin E1 were determined and assessed by RT- PCR, ELISA, and western blotting. It was found that theasaponin E1 reduced hyperphosphorylation of tau and Aβ concentrations significantly, and dose-dependently, by suppressing the expression of GSK3 β, CDK5, CAMII, MAPK, EPOE4(E4), and PICALM, and enhanced the expression of PP1, PP2A, and TREM2. According to the ELISA and western blotting results, the levels of APP, Aβ, and p-tau were reduced by treatment with theasaponin E1. Moreover, theasaponin E1 reduced inflammation by suppressing the Nf-kB pathway and dose-dependently reducing the levels of inflammatory cytokines such as IL-1beta, IL-6, and TNF-alpha etc.

Astrocytic α2-Na+/K+ ATPase inhibition suppresses astrocyte reactivity and reduces neurodegeneration in a tauopathy mouse model

Alzheimer's disease (AD) is the most dominant form of dementia characterized by the deposition of extracellular amyloid plaques and intracellular neurofibrillary tau tangles (NFTs). In addition to these pathologies, an emerging pathophysiological mechanism that influences AD is neuroinflammation. Astrocytes are a vital type of glial cell that contribute to neuroinflammation, and reactive astrocytes, or astrogliosis, are a well-known pathological feature of AD. However, the mechanisms by which astrocytes contribute to the neurodegenerative process in AD have not been fully elucidated. Here, we showed that astrocytic α2-Na⁺/K⁺ adenosine triphosphatase (α2-NKA) is elevated in postmortem human brain tissue from AD and progressive nuclear palsy, a primary tauopathy. The increased astrocytic α2-NKA was also recapitulated in a mouse model of tauopathy. Pharmacological inhibition of α2-NKA robustly suppressed neuroinflammation and reduced brain atrophy. In addition, α2-NKA knockdown in tauopathy mice halted the accumulation of tau pathology. We also demonstrated that α2-NKA promoted tauopathy, in part, by regulating the proinflammatory protein lipocalin-2 (Lcn2). Overexpression of Lcn2 in tauopathy mice increased tau pathology, and prolonged Lcn2 exposure to primary neurons promoted tau uptake in vitro. These studies collectively highlight the contribution of reactive astrocytes to tau pathogenesis in mice and define α2-NKA as a major regulator of astrocytic-dependent neuroinflammation.

ICAM-1 protects neurons against Amyloid-β and improves cognitive behaviors in 5xFAD mice by inhibiting NF-κB

Alzheimer's disease (AD) is mainly characterized by amyloid beta (Aβ) plaque deposition and neurofibrillary tangle formation due to tau hyperphosphorylation. It has been shown that astrocytes respond to these pathologies very early and exert either beneficial or deleterious effects towards neurons. Here, we identified soluble intercellular adhesion molecule-1 (ICAM-1) which is rapidly increased in astrocyte conditioned medium derived from Aβ_1-42 treated cultured astrocytes (Aβ_1-42-ACM). Aβ_1-42-ACM was found to be neuroprotective, however, Aβ_1-42-ACM deprived of ICAM-1 was unable to protect neurons against Aβ_1-42 mediated toxicity. Moreover, exogenous ICAM-1 renders protection to neurons from Aβ_1-42 induced death. It blocks Aβ_1-42-mediated PARP cleavage and increases the levels of anti-apoptotic proteins such as Bcl-2 and Bcl-xL, and decreases pro-apoptotic protein Bim. In an Aβ-infused rat model of AD and in 5xFAD mouse, intra-peritoneal administration of ICAM-1 revealed a reduction in Aβ load in hippocampal and cortical regions. Moreover, ICAM-1 treatment led to an increment in the expression of the Aβ-degrading enzyme, neprilysin in 5xFAD mice. Finally, we found that ICAM-1 can ameliorate cognitive deficits in Aβ-infused rat and 5xFAD mouse. Interestingly, ICAM-1 could block the NF-κB upregulation by Aβ and inhibition of NF-κB recovers cognitive impairments in 5xFAD mice. Thus, our study finds a neuroprotective role of ICAM-1 and suggests that it can be a major candidate in cytokine-mediated therapy of AD.

Probiotics for Alzheimer's Disease: A Systematic Review

Alzheimer’s disease (AD) is the most common form of neurodegenerative disorders affecting mostly the elderly. It is characterized by the presence of Aβ and neurofibrillary tangles (NFT), resulting in cognitive and memory impairment. Research shows that alteration in gut microbial diversity and defects in gut brain axis are linked to AD. Probiotics are known to be one of the best preventative measures against cognitive decline in AD. Numerous in vivo trials and recent clinical trials have proven the effectiveness of selected bacterial strains in slowing down the progression of AD. It is proven that probiotics modulate the inflammatory process, counteract with oxidative stress, and modify gut microbiota. Thus, this review summarizes the current evidence, diversity of bacterial strains, defects of gut brain axis in AD, harmful bacterial for AD, and the mechanism of action of probiotics in preventing AD. A literature search on selected databases such as PubMed, Semantic Scholar, Nature, and Springer link have identified potentially relevant articles to this topic. However, upon consideration of inclusion criteria and the limitation of publication year, only 22 articles have been selected to be further reviewed. The search query includes few sets of keywords as follows. (1) Probiotics OR gut microbiome OR microbes AND (2) Alzheimer OR cognitive OR aging OR dementia AND (3) clinical trial OR in vivo OR animal study. The results evidenced in this study help to clearly illustrate the relationship between probiotic supplementation and AD. Thus, this systematic review will help identify novel therapeutic strategies in the future as probiotics are free from triggering any adverse effects in human body.

Pinoresinol diglucoside alleviates ischemia/reperfusion-induced brain injury by modulating neuroinflammation and oxidative stress

Brain ischemia/reperfusion (I/R) injury is a common pathological process after ischemic stroke. Pinoresinol diglucoside (PDG) has antioxidation and anti-inflammation activities. However, whether PDG ameliorates brain I/R injury is still unclear. In this study, middle cerebral artery occlusion (MCAO) model was established with male C57BL/6 mice, and the mice were treated with 5 and 10 mg/kg PDG via intravenous injection, respectively. The neurological deficit, infarct volume, and brain water content were then evaluated. HE staining and Nissl staining were used to analyze neuron injury. Besides, enzyme-linked immunosorbent assay and colorimetry assay were used to examine the level of inflammatory markers and oxidative stress markers, and Western blot was used to detect the expressions of p-p65, Nrf2, and HO-1. It was revealed that PDG could significantly alleviate the MCAO-induced neurological dysfunction of the mice and reduce the infarct volume, brain water content, and neuron injury. PDG treatment decreased the levels of TNF-α, IL-1β, IL-6, NO, ROS, and MDA, and significantly increased the activities of SOD, GSH, and GSH-Px in the brain tissue of the mice. Additionally, PDG could repress the activation of p65 and promote Nrf2 and HO-1 expressions. In conclusion, PDG exerts anti-inflammatory and antioxidation effects via regulating the NF-κB pathway and Nrf2/HO-1 pathway, thereby reducing the I/R-induced brain injury of mice.

IKK2/NF-κB Activation in Astrocytes Reduces amyloid β Deposition: A Process Associated with Specific Microglia Polarization

Alzheimer's disease (AD) is a common neurodegenerative disease that is accompanied by pronounced neuroinflammatory responses mainly characterized by marked microgliosis and astrogliosis. However, it remains open as to how different aspects of astrocytic and microglial activation affect disease progression. Previously, we found that microglia expansion in the spinal cord, initiated by IKK2/NF-κB activation in astrocytes, exhibits stage-dependent beneficial effects on the progression of amyotrophic lateral sclerosis. Here, we investigated the impact of NF-κB-initiated neuroinflammation on AD pathogenesis using the APP23 mouse model of AD in combination with conditional activation of IKK2/NF-κB signaling in astrocytes. We show that NF-κB activation in astrocytes triggers a distinct neuroinflammatory response characterized by striking astrogliosis as well as prominent microglial reactivity. Immunohistochemistry and Congo red staining revealed an overall reduction in the size and number of amyloid plaques in the cerebral cortex and hippocampus. Interestingly, isolated primary astrocytes and microglia cells exhibit specific marker gene profiles which, in the case of microglia, point to an enhanced plaque clearance capacity. In contrast, direct IKK2/NF-κB activation in microglia results in a pro-inflammatory polarization program. Our findings suggest that IKK2/NF-κB signaling in astrocytes may activate paracrine mechanisms acting on microglia function but also on APP processing in neurons.

The Many Faces of Astrocytes in Alzheimer's Disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease and is the most common cause of dementia in an aging population. The majority of research effort has focused on the role of neurons in neurodegeneration and current therapies have limited ability to slow disease progression. Recently more attention has been given to the role of astrocytes in the process of neurodegeneration. Specifically, reactive astrocytes have both advantageous and adverse effects during neurodegeneration. The ability to isolate and depict astrocyte phenotype has been challenging. However, with the recent development of single-cell sequencing technologies researchers are provided with the resource to delineate specific biomarkers associated with reactive astrocytes in AD. In this review, we will focus on the role of astrocytes in normal conditions and the pathological development of AD. We will further review recent developments in the understanding of astrocyte heterogeneity and associated biomarkers. A better understanding of astrocyte contributions and phenotypic changes in AD can ultimately lead to more effective therapeutic targets.

Neuroinflammatory Signaling in the Pathogenesis of Alzheimer's Disease

Alzheimer’s disease (AD) is a chronic neurodegenerative disease characterized by the formation of intracellular neurofibrillary tangles (NFTs) and extracellular amyloid plaques. Growing evidence has suggested that AD pathogenesis is not only limited to the neuronal compartment but also strongly interacts with immunological processes in the brain. On the other hand, aggregated and misfolded proteins can bind with pattern recognition receptors located on astroglia and microglia and can, in turn, induce an innate immune response, characterized by the release of inflammatory mediators, ultimately playing a role in both the severity and the progression of the disease. It has been reported by genome-wide analysis that several genes which elevate the risk for sporadic AD encode for factors controlling the inflammatory response and glial clearance of misfolded proteins. Obesity and systemic inflammation are examples of external factors which may interfere with the immunological mechanisms of the brain and can induce disease progression. In this review, we discussed the mechanisms and essential role of inflammatory signaling pathways in AD pathogenesis. Indeed, interfering with immune processes and modulation of risk factors may lead to future therapeutic or preventive AD approaches.

Role of NF-κB in Ageing and Age-Related Diseases: Lessons from Genetically Modified Mouse Models

Ageing is a complex process, induced by multifaceted interaction of genetic, epigenetic, and environmental factors. It is manifested by a decline in the physiological functions of organisms and associated to the development of age-related chronic diseases and cancer development. It is considered that ageing follows a strictly-regulated program, in which some signaling pathways critically contribute to the establishment and maintenance of the aged state. Chronic inflammation is a major mechanism that promotes the biological ageing process and comorbidity, with the transcription factor NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) as a crucial mediator of inflammatory responses. This, together with the finding that the activation or inhibition of NF-κB can induce or reverse respectively the main features of aged organisms, has brought it under consideration as a key transcription factor that acts as a driver of ageing. In this review, we focused on the data obtained entirely through the generation of knockout and transgenic mouse models of either protein involved in the NF-κB signaling pathway that have provided relevant information about the intricate processes or molecular mechanisms that control ageing. We have reviewed the relationship of NF-κB and premature ageing; the development of cancer associated with ageing and the implication of NF-κB activation in the development of age-related diseases, some of which greatly increase the risk of developing cancer.

Sinensetin Attenuates Amyloid Beta25-35-Induced Oxidative Stress, Inflammation, and Apoptosis in SH-SY5Y Cells Through the TLR4/NF-κB Signaling Pathway

Sinensetin (SIN) is an important active compound that exists widely in citrus plants, and has been reported to exhibit various pharmacological properties, including anti-oxidative, anti-inflammatory, and anti-tumor. This study was designed to examine whether SIN can protect against amyloid beta (Aβ)-induced neurotoxicity and to elucidate the underlying mechanism. Our results showed that pretreatment with SIN for 1 h, followed by co-treatment with Aβ plus SIN for 24 h, attenuated Aβ_25-35-induced cell viability reduction, oxidative stress, inflammation, and apoptosis in a dose-dependent manner. Aβ_25-35-induced upregulation of Toll-like receptor 4 (TLR4) expression and nuclear translocation of nuclear factor-kappaB (NF-κB) p65 subunit were inhibited by pretreatment with SIN. Furthermore, the protective effect of SIN was abrogated by TLR4 overexpression. Hence, our data suggested that SIN attenuated Aβ_25-35-induced neurotoxicity through the TLR4/NF-κB pathway.

Does oxidatively damaged DNA drive amyloid-β generation in Alzheimer's disease? A hypothesis

In Alzheimer's disease (AD), amyloid-β (Aβ) generation and upstream β-secretase 1 (BACE1) expression appear to be driven by oxidative stress via c-Jun N-terminal kinase (JNK), p38, and Interferon-Induced, Double-Stranded RNA-Activated Protein Kinase (PKR). In addition, inflammatory molecules, including lipopolysaccharide (LPS), induce genes central to Aβ genesis, such as BACE1, via nuclear factor-κB (NFκB). However, additional triggers of Aβ generation remain poorly understood and might represent novel opportunities for therapeutic intervention. Based on mechanistic studies and elevated ectopic oxidatively damaged DNA (oxoDNA) levels in preclinical AD, mild cognitive impairment, and AD patients, we hypothesize oxoDNA contributes to β-amyloidosis starting from the earliest stages of AD through multiple pathways. OxoDNA induces mitogen-activated protein kinase kinase kinase kinase 4 (MAP4K4), thereby sensitizing the brain to oxidative stress-induced JNK activation and BACE1 transcription. It also induces myeloid differentiation primary response 88 (MyD88) and activates protein kinase CK2, thereby increasing NFκB activation and BACE1 induction. OxoDNA increases oxidative stress via nuclear factor erythroid 2-related factor 2 (Nrf2) ectopic localization, likely augmenting JNK-mediated BACE1 induction. OxoDNA likely also promotes β-amyloidosis via absent in melanoma 2 (AIM2) induction. Falsifiable predictions of this hypothesis include that deoxyribonuclease treatment should decrease Aβ and possibly slow cognitive decline in AD patients. While formal testing of this hypothesis remains to be performed, a case report has found deoxyribonuclease I treatment improved a severely demented AD patient's Mini-Mental Status Exam score from 3 to 18 at 2 months. There is preliminary preclinical and clinical evidence suggesting that ectopic oxidatively damaged DNA may act as an inflammatory damage-associated molecular pattern contributing to Aβ generation in AD, and deoxyribonuclease I should be formally evaluated to test whether it can decrease Aβ levels and slow cognitive decline in AD patients.

Activity of Selected Group of Monoterpenes in Alzheimer's Disease Symptoms in Experimental Model Studies-A Non-Systematic Review

Alzheimer's disease (AD) is the leading cause of dementia and cognitive function impairment. The multi-faced character of AD requires new drug solutions based on substances that incorporate a wide range of activities. Antioxidants, AChE/BChE inhibitors, BACE1, or anti-amyloid platelet aggregation substances are most desirable because they improve cognition with minimal side effects. Plant secondary metabolites, used in traditional medicine and pharmacy, are promising. Among these are the monoterpenes-low-molecular compounds with anti-inflammatory, antioxidant, enzyme inhibitory, analgesic, sedative, as well as other biological properties. The presented review focuses on the pathophysiology of AD and a selected group of anti-neurodegenerative monoterpenes and monoterpenoids for which possible mechanisms of action have been explained. The main body of the article focuses on monoterpenes that have shown improved memory and learning, anxiolytic and sleep-regulating effects as determined by in vitro and in silico tests-followed by validation in in vivo models.

Challenges with Methods for Detecting and Studying the Transcription Factor Nuclear Factor Kappa B (NF-κB) in the Central Nervous System

The transcription factor nuclear factor kappa B (NF-κB) is highly expressed in almost all types of cells. NF-κB is involved in many complex biological processes, in particular in immunity. The activation of the NF-κB signaling pathways is also associated with cancer, diabetes, neurological disorders and even memory. Hence, NF-κB is a central factor for understanding not only fundamental biological presence but also pathogenesis, and has been the subject of intense study in these contexts. Under healthy physiological conditions, the NF-κB pathway promotes synapse growth and synaptic plasticity in neurons, while in glia, NF-κB signaling can promote pro-inflammatory responses to injury. In addition, NF-κB promotes the maintenance and maturation of B cells regulating gene expression in a majority of diverse signaling pathways. Given this, the protein plays a predominant role in activating the mammalian immune system, where NF-κB-regulated gene expression targets processes of inflammation and host defense. Thus, an understanding of the methodological issues around its detection for localization, quantification, and mechanistic insights should have a broad interest across the molecular neuroscience community. In this review, we summarize the available methods for the proper detection and analysis of NF-κB among various brain tissues, cell types, and subcellular compartments, using both qualitative and quantitative methods. We also summarize the flexibility and performance of these experimental methods for the detection of the protein, accurate quantification in different samples, and the experimental challenges in this regard, as well as suggestions to overcome common challenges.

Amyloids: The History of Toxicity and Functionality

Proteins can perform their specific function due to their molecular structure. Partial or complete unfolding of the polypeptide chain may lead to the misfolding and aggregation of proteins in turn, resulting in the formation of different structures such as amyloid aggregates. Amyloids are rigid protein aggregates with the cross-β structure, resistant to most solvents and proteases. Because of their resistance to proteolysis, amyloid aggregates formed in the organism accumulate in tissues, promoting the development of various diseases called amyloidosis, for instance Alzheimer's diseases (AD). According to the main hypothesis, it is considered that the cause of AD is the formation and accumulation of amyloid plaques of Aβ. That is why Aβ-amyloid is the most studied representative of amyloids. Therefore, in this review, special attention is paid to the history of Aβ-amyloid toxicity. We note the main problems with anti-amyloid therapy and write about new views on amyloids that can play positive roles in the different organisms including humans.

Alternative Targets to Fight Alzheimer's Disease: Focus on Astrocytes

The available treatments for patients affected by Alzheimer’s disease (AD) are not curative. Numerous clinical trials have failed during the past decades. Therefore, scientists need to explore new avenues to tackle this disease. In the present review, we briefly summarize the pathological mechanisms of AD known so far, based on which different therapeutic tools have been designed. Then, we focus on a specific approach that is targeting astrocytes. Indeed, these non-neuronal brain cells respond to any insult, injury, or disease of the brain, including AD. The study of astrocytes is complicated by the fact that they exert a plethora of homeostatic functions, and their disease-induced changes could be context-, time-, and disease specific. However, this complex but fervent area of research has produced a large amount of data targeting different astrocytic functions using pharmacological approaches. Here, we review the most recent literature findings that have been published in the last five years to stimulate new hypotheses and ideas to work on, highlighting the peculiar ability of palmitoylethanolamide to modulate astrocytes according to their morpho-functional state, which ultimately suggests a possible potential disease-modifying therapeutic approach for AD.

Mechanism of action and cellular responses of HEK293 cells on challenge with zwitterionic carbon dots

Carbon, an extremely versatile element has great demand in the field of nanoscience. Carbon-based nanostructures are exponentially increased due to its wide range of applications in biotechnological and environmental approaches; hence, its safety assessment is of greater concern. In the present study, high quantum yielding zwitterionic carbon dots were synthesized, characterized and its safety assessment at different concentration ranges (50-1600 μgmL^-1) on HEK 293 cells was carried out. Cellular, mitochondrial, lysosomal integrity and ROS generation were assessed using specific fluorochromes.The key cellular event apoptosis was assessed by annexinpropidium iodide staining using imaging flow cytometry. Moreover, the mRNA levels of the apoptotic genes were determined by real-time PCR. The results revealed that the cell viability assays (MTT, NR) and mitochondrial membrane potential were altered on exposure to a higher concentration of zwitterionic CDs for 24 h. Also, annexinpropidiumiodidestaining exhibited an increased percentage of apoptotic cells upon exposure to zwitterionic CDs at higher concentrations. Further, apoptosis was confirmed by significantlyincreased expression of pro-apoptotic gene (Bax) together with decreased expression of Bcl-2/Bax ratio. Collectively, this study suggests that zwitterionic CDs induce apoptosis in HEK 293 at higher concentration and the safe range for its intended application is found to be 50-200 μg/mL.