The acute phase protein lactoferrin is a key feature of Alzheimer's disease and predictor of Aβ burden through induction of APP amyloidogenic processing

Repurposing pharmaceuticals for Alzheimer's treatment via adjusting the lactoferrin interacting proteins

Alzheimer's disease (AD), the most common neurodegenerative disease in humans, has been a major medical challenge. Lactoferrin (Ltf) in salivary glands might be identified as a potential detectable biomarker in AD and a therapeutic target for AD. Pharmaceutical studies directly addressing this biomarker, though, are scarce. Using a computational strategy for drug repurposing, we explored the proximal neighborhood of Ltf by exploring its interactome and regulatory constellations. We aimed to focus on the discovery of potential therapeutic agents for AD. Based on extensive analytical evaluation comprising structural congruence scales, profiling disease clusters, pathway enrichment analyses as well as molecular docking, SPR, in vivo studies, and immunofluorescence assays, our research identified three candidate repurposed drugs: Lovastatin, SU-11652, and SB-239063. Taken together, these results highlight strong binding affinities of the drug candidates to Ltf. In vitro studies showed that such compounds decrease β-amyloid (Aβ) production by increasing the fluorescence signal emitted by Ltf in N2a-sw cells, and that they act by modulating the expression of amyloidogenic pathway-associated enzymes (BACE1 and APH1α). In addition, in vivo studies showed a concomitant reduction in the expression levels of amyloidogenic pathway-related enzymes (BACE1 or APH1α). Thus, computational studies have focused on Ltf interactions that may recommend drug repurposing strategies and options for AD.

Effective integration of multi-omics with prior knowledge to identify biomarkers via explainable graph neural networks

The rapid growth of multi-omics datasets and the wealth of biological knowledge necessitates the development of effective methods for their integration. Such methods are essential for building predictive models and identifying drug targets based on a limited number of samples. We propose a framework called GNNRAI for the supervised integration of multi-omics data with biological priors represented as knowledge graphs. Our framework leverages graph neural networks (GNNs) to model the correlation structures among features from high-dimensional 'omics data, which reduces the effective dimensions in data and enables us to analyze thousands of genes simultaneously using hundreds of samples. Furthermore, our framework incorporates explainability methods to elucidate informative biomarkers. We apply our framework to Alzheimer's disease (AD) multi-omics data, showing that the integration of transcriptomics and proteomics data with prior AD knowledge is effective, improving the prediction accuracy of AD status over single-omics analyses and highlighting both known and novel AD-predictive biomarkers.

Ferroptosis in Alzheimer's Disease: The Regulatory Role of Glial Cells

Alzheimer's disease (AD) is a neurodegenerative disease characterized by the formation of amyloid plaques, neurofibrillary tangles and progressive cognitive decline. Amyloid-beta peptide (Aβ) monoclonal antibody therapeutic clinical trials have nearly failed, raising significant concerns about other etiological hypotheses about AD. Recent evidence suggests that AD patients also exhibit persistent neuronal loss and neuronal death accompanied by brain iron deposition or overload-related oxidative stress. Ferroptosis is a type of cell death that depends on iron, unlike autophagy and apoptosis. Inhibiting neuronal ferroptosis function is effective in improving cognitive impairment in AD. Notably, new research shows that ferroptosis in AD is crucially dependent on glial cell activation. This review examines the relationship between the imbalance of iron metabolism, the regulation of iron homeostasis in glial cells and neuronal death in AD pathology. Finally, the review summarizes some current drug research in AD targeting iron homeostasis, many novel iron-chelating compounds and natural compounds showing potential AD-modifying properties that may provide therapeutic targets for treating AD.

Lactoferrin as a Candidate Multifunctional Therapeutic in Synucleinopathies

Lactoferrin (Lf) is a multifunctional glycoprotein with well-established antimicrobial, anti-inflammatory, and iron-binding properties. Emerging evidence suggests that Lf also plays a neuroprotective role, particularly in neurodegenerative disorders characterized by protein aggregation, such as Parkinson's disease (PD). Alpha-synuclein (aSyn) aggregation is a pathological hallmark of PD and other synucleinopathies, contributing to neuronal dysfunction and disease progression. Recent studies indicate that Lf may interfere with aSyn aggregation, iron chelation, and modulation of oxidative stress and neuroinflammation. Additionally, Lf's ability to cross the blood-brain barrier and its potential impact on the gut-brain axis highlight its promise as a therapeutic agent. This review explores Lf's mechanisms of action in synucleinopathies, its potential as a disease-modifying therapy, and innovative delivery strategies that could enhance its clinical applicability. By addressing the pathological and therapeutic dimensions of aSyn aggregation, we propose Lf as a compelling candidate for future research and clinical development in neurodegenerative diseases.

Liposomal Lactoferrin Reduces Brain Neuroinflammation in Rats and Alleviates Jetlag and Improves Sleep Quality After Long-Haul Travel

Insufficient sleep and circadian misalignment increase inflammatory agents. This triggers neuroinflammation and can result in health issues including depression, dementia, lifestyle-related diseases, and industrial accidents. Lactoferrin (LF) confers neuroprotective effects, which are derived from its anti-inflammatory, antioxidant, and iron metabolic properties; however, its roles in acute neuroinflammation and circadian rhythm disruption are yet to be elucidated. Therefore, we aimed to test the effects of LF on rat neuroinflammation and sleep and jetlag in humans. Rats received 7 days of an oral liposomal bovine LF (L-bLF) or vehicle followed by polyriboinosinic:polyribocytidylic acid (poly I:C) peritoneal injections (n = 5-6). Compared with the rats given poly I:C only, the rats given L-bLF and poly I:C had lower Il1b, Tnf, Casp1, Nfe212, Gclm, and Sod2 expression in the hippocampus. This open-label pilot study was carried out on tour conductors performing regular international tour responsibilities, and the data were compared between the initial tour without L-bLF intake and the subsequent tour with L-bLF intake. In the tour with L-bLF intake, L-bLF administration started from one week before the trip and was continued during the trip. In both periods, the tour conductors experienced limited sleep; however, both subjective and objective sleep quality was significantly better with the oral L-bLF intake than without. Overall, we found that prophylactic L-bLF supplementation reduced neuroinflammation in rat hippocampi and improved sleep quality and jetlag in tour conductors.

An Update of Salivary Biomarkers for the Diagnosis of Alzheimer's Disease

Alzheimer's disease (AD) is characterized by progressive cognition and behavior impairments. Diagnosing AD early is important for clinicians to slow down AD progression and preserve brain function. Biomarkers such as tau protein and amyloid-β peptide (Aβ) are used to aid diagnosis as clinical diagnosis often lags. Additionally, biomarkers can be used to monitor AD status and evaluate AD treatment. Clinicians detect these AD biomarkers in the brain using positron emission tomography/computed tomography or in the cerebrospinal fluid using a lumbar puncture. However, these methods are expensive and invasive. In contrast, saliva collection is simple, inexpensive, non-invasive, stress-free, and repeatable. Moreover, damage to the brain parenchyma can impact the oral cavity and some pathogenic molecules could travel back and forth from the brain to the mouth. This has prompted researchers to explore biomarkers in the saliva. Therefore, this study provides an overview of the main finding of salivary biomarkers for AD diagnosis. Based on these available studies, Aβ, tau, cholinesterase enzyme activity, lactoferrin, melatonin, cortisol, proteomics, metabolomics, exosomes, and the microbiome were changed in AD patients' saliva when compared to controls. However, well-designed studies are essential to confirm the reliability and validity of these biomarkers in diagnosing and monitoring AD.

The Association of Serum Lactoferrin Level with Psychological Symptoms, Cognition, and Executive Function in Schizophrenia Patients

Objective: Lactoferrin, a glycoprotein, has known neuroprotective effects, yet its role in the pathophysiology of neuropsychiatric disorders, particularly schizophrenia, remains unclear. This study aims to assess changes in lactoferrin levels during different phases of schizophrenia and explore its relationship with cognitive symptoms and performance. Method : This before/after interventional study involved 30 patients diagnosed with schizophrenia. Participants were evaluated at two time points: upon hospital admission and after the resolution of acute symptoms. The Positive and Negative Syndrome Scale (PANSS) was utilized to measure symptom severity, while the Brief Assessment of Cognition in Schizophrenia (BACS) assessed the neurocognitive function. Serum lactoferrin levels were quantified using the Enzyme-Linked Immunosorbent Assay (ELISA) method. Results: Serum lactoferrin levels significantly decreased from 130.63 ± 52.49 ng/mL at admission to 85.42 ± 29.03 ng/mL at discharge (P < 0.001). No significant correlation was found between lactoferrin levels and PANSS scores (r = 0.011, P = 0.975). However, an inverse correlation was observed between changes in lactoferrin levels and the executive function subscale of the BACS (r = -0.360, P = 0.050). Cognitive assessments indicated significant improvements in verbal memory (P = 0.033), working memory (P = 0.002), and executive function (P = 0.039) post-treatment. Conclusion: The study demonstrates a significant reduction in serum lactoferrin levels during the acute phase of schizophrenia, suggesting its potential role in modulating cognitive functions, particularly the executive function, rather than influencing positive or negative symptoms.

Astrocyte-derived lactoferrin inhibits neuronal ferroptosis by reducing iron content and GPX4 degradation in APP/PS1 transgenic mice

Increased astrocytic lactoferrin (Lf) expression was observed in the brains of elderly individuals and Alzheimer's disease (AD) patients. Our previous study revealed that astrocytic Lf overexpression improved cognitive capacity by facilitating Lf secretion to neurons to inhibit β-amyloid protein (Aβ) production in APP/PS1 mice. Here, we further discovered that astrocytic Lf overexpression inhibited neuronal loss by decreasing iron accumulation and increasing glutathione peroxidase 4 (GPX4) expression in neurons within APP/PS1 mice. Furthermore, human Lf (hLf) treatment inhibited ammonium ferric citrate (FAC)-induced ferroptosis by chelating intracellular iron. Additionally, machine learning analysis uncovered a correlation between Lf and GPX4. hLf treatment boosted low-density lipoprotein receptor-related protein 1 (LRP1) internalization and facilitated its interaction with heat shock cognate 70 (HSC70), thereby inhibiting HSC70 binds to GPX4, and eventually attenuating GPX4 degradation and FAC-induced ferroptosis. Overall, astrocytic Lf overexpression inhibited neuronal ferroptosis through two pathways: reducing intracellular iron accumulation and promoting GPX4 expression via inhibiting chaperone-mediated autophagy (CMA)-mediated GPX4 degradation. Hence, upregulating astrocytic Lf expression is a promising strategy for combating AD.

A Map of Transcriptomic Signatures of Different Brain Areas in Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder that progressively involves brain regions with an often-predictable pattern. Damage to the brain appears to spread and worsen with time, but the molecular mechanisms underlying the region-specific distribution of AD pathology at different stages of the disease are still under-investigated. In this study, a whole-transcriptome analysis was carried out on brain samples from the hippocampus (HI), temporal and parietal cortices (TC and PC, respectively), cingulate cortex (CG), and substantia nigra (SN) of six subjects with a definite AD diagnosis and three healthy age-matched controls in duplicate. The transcriptomic results showed a greater number of differentially expressed genes (DEGs) in the TC (1571) and CG (1210) and a smaller number of DEGs in the HI (206), PC (109), and SN (60). Furthermore, the GSEA showed a difference between the group of brain areas affected early (HI and TC) and the group of areas that were subsequently involved (PC, CG, and SN). Notably, in the HI and TC, there was a significant downregulation of shared DEGs primarily involved in synaptic transmission, while in the PC, CG, and SN, there was a significant downregulation of genes primarily involved in protein folding and trafficking. The course of AD could follow a definite time- and severity-related pattern that arises from protein misfolding, as observed in the PC, CG, and SN, and leads to synaptic impairment, as observed in the HI and TC. Therefore, a map of the molecular and biological processes involved in AD pathogenesis may be traced. This could aid in the discovery of novel biological targets in order to develop effective and well-timed therapeutic approaches.

MAD-microbial (origin of) Alzheimer's disease hypothesis: from infection and the antimicrobial response to disruption of key copper-based systems

Microbes have been suspected to cause Alzheimer's disease since at least 1908, but this has generally remained unpopular in comparison to the amyloid hypothesis and the dominance of Aβ and Tau. However, evidence has been accumulating to suggest that these earlier theories are but a manifestation of a common cause that can trigger and interact with all the major molecular players recognized in AD. Aβ, Tau and ApoE, in particular appear to be molecules with normal homeostatic functions but also with alternative antimicrobial functions. Their alternative functions confer the non-immune specialized neuron with some innate intracellular defenses that appear to be re-appropriated from their normal functions in times of need. Indeed, signs of infection of the neurons by biofilm-forming microbial colonies, in synergy with herpes viruses, are evident from the clinical and preclinical studies we discuss. Furthermore, we attempt to provide a mechanistic understanding of the AD landscape by discussing the antimicrobial effect of Aβ, Tau and ApoE and Lactoferrin in AD, and a possible mechanistic link with deficiency of vital copper-based systems. In particular, we focus on mitochondrial oxidative respiration via complex 4 and ceruloplasmin for iron homeostasis, and how this is similar and possibly central to neurodegenerative diseases in general. In the case of AD, we provide evidence for the microbial Alzheimer's disease (MAD) theory, namely that AD could in fact be caused by a long-term microbial exposure or even long-term infection of the neurons themselves that results in a costly prolonged antimicrobial response that disrupts copper-based systems that govern neurotransmission, iron homeostasis and respiration. Finally, we discuss potential treatment modalities based on this holistic understanding of AD that incorporates the many separate and seemingly conflicting theories. If the MAD theory is correct, then the reduction of microbial exposure through use of broad antimicrobial and anti-inflammatory treatments could potentially alleviate AD although this requires further clinical investigation.

An explainable graph neural network approach for effectively integrating multi-omics with prior knowledge to identify biomarkers from interacting biological domains

The rapid growth of multi-omics datasets, in addition to the wealth of existing biological prior knowledge, necessitates the development of effective methods for their integration. Such methods are essential for building predictive models and identifying disease-related molecular markers. We propose a framework for supervised integration of multi-omics data with biological priors represented as knowledge graphs. Our framework leverages graph neural networks (GNNs) to model the relationships among features from high-dimensional 'omics data and set transformers to integrate low-dimensional representations of 'omics features. Furthermore, our framework incorporates explainability methods to elucidate important biomarkers and extract interaction relationships between biological quantities of interest. We demonstrate the effectiveness of our approach by applying it to Alzheimer's disease (AD) multi-omics data from the ROSMAP cohort, showing that the integration of transcriptomics and proteomics data with AD biological domain network priors improves the prediction accuracy of AD status and highlights functional AD biomarkers.

Identification and immunological characterization of genes associated with ferroptosis in Alzheimer's disease and experimental demonstration

The incidence of Alzheimer's disease (AD) is rising globally, yet its treatment and prediction of this condition remain challenging due to the complex pathophysiological mechanisms associated with it. Consequently, the objective of the present study was to analyze and characterize the molecular mechanisms underlying ferroptosis‑related genes (FEGs) in the pathogenesis of AD, as well as to construct a prognostic model. The findings will provide new insights for the future diagnosis and treatment of AD. First, the AD dataset GSE33000 from the Gene Expression Omnibus database and the FEGs from FerrDB were obtained. Next, unsupervised cluster analysis was used to obtain the FEGs that were most relevant to AD. Subsequently, enrichment analyses were performed on the FEGs to explore biological functions. Subsequently, the role of these genes in the immune microenvironment was elucidated through CIBERSORT. Then, the optimal machine learning was selected by comparing the performance of different machine learning models. To validate the prediction efficiency, the models were validated using nomograms, calibration curves, decision curve analysis and external datasets. Furthermore, the expression of FEGs between different groups was verified using reverse transcription quantitative PCR and western blot analysis. In AD, alterations in the expression of FEGs affect the aggregation and infiltration of certain immune cells. This indicated that the occurrence of AD is strongly associated with immune infiltration. Finally, the most appropriate machine learning models were selected, and AD diagnostic models and nomograms were built. The present study provided novel insights that enhance understanding with regard to the molecular mechanism of action of FEGs in AD. Moreover, the present study provided biomarkers that may facilitate the diagnosis of AD.

Regulation of FSP1 myristoylation by NADPH: A novel mechanism for ferroptosis inhibition

Excitotoxicity is a prevalent pathological event in neurodegenerative diseases. The involvement of ferroptosis in the pathogenesis of excitotoxicity remains elusive. Transcriptome analysis has revealed that cytoplasmic reduced nicotinamide adenine dinucleotide phosphate (NADPH) levels are associated with susceptibility to ferroptosis-inducing compounds. Here we show that exogenous NADPH, besides being reductant, interacts with N-myristoyltransferase 2 (NMT2) and upregulates the N-myristoylated ferroptosis suppressor protein 1 (FSP1). NADPH increases membrane-localized FSP1 and strengthens resistance to ferroptosis. Arg-291 of NMT2 is critical for the NADPH-NMT2-FSP1 axis-mediated suppression of ferroptosis. This study suggests that NMT2 plays a pivotal role by bridging NADPH levels and neuronal susceptibility to ferroptosis. We propose a mechanism by which the NADPH regulates N-myristoylation, which has important implications for ferroptosis and disease treatment.

Host defense amyloids: Biosensors of the immune system?

There is considerable evidence showing that highly ordered aggregate structures known as amyloids carry out essential biological roles in species ranging from bacteria to humans. Indeed, many antimicrobial peptides/proteins form amyloids to carry out their host defense functions and many amyloids are antimicrobial. The similarity of host defense amyloids from bacterial biofilms to the mammalian epididymal amyloid matrix implies highly conserved host defense structures/functions. With an emphasis on the epididymal amyloid matrix, here we review the common properties of host defense amyloids including unique traits that would allow them to function as powerful biosensors of the immune system.

E3 ligases and DUBs target ferroptosis: A potential therapeutic strategy for neurodegenerative diseases

Ferroptosis is a form of cell death mediated by iron and lipid peroxidation (LPO). Recent studies have provided compelling evidence to support the involvement of ferroptosis in the pathogenesis of various neurodegenerative diseases (NDDs), such as Alzheimer's disease (AD), Parkinson's disease (PD). Therefore, understanding the mechanisms that regulate ferroptosis in NDDs may improve disease management. Ferroptosis is regulated by multiple mechanisms, and different degradation pathways, including autophagy and the ubiquitinproteasome system (UPS), orchestrate the complex ferroptosis response by directly or indirectly regulating iron accumulation or lipid peroxidation. Ubiquitination plays a crucial role as a protein posttranslational modification in driving ferroptosis. Notably, E3 ubiquitin ligases (E3s) and deubiquitinating enzymes (DUBs) are key enzymes in the ubiquitin system, and their dysregulation is closely linked to the progression of NDDs. A growing body of evidence highlights the role of ubiquitin system enzymes in regulating ferroptosis sensitivity. However, reports on the interaction between ferroptosis and ubiquitin signaling in NDDs are scarce. In this review, we first provide a brief overview of the biological processes and roles of the UPS, summarize the core molecular mechanisms and potential biological functions of ferroptosis, and explore the pathophysiological relevance and therapeutic implications of ferroptosis in NDDs. In addition, reviewing the roles of E3s and DUBs in regulating ferroptosis in NDDs aims to provide new insights and strategies for the treatment of NDDs. These include E3- and DUB-targeted drugs and ferroptosis inhibitors, which can be used to prevent and ameliorate the progression of NDDs.

Astrocyte-derived lactoferrin reduces β-amyloid burden by promoting the interaction between p38 kinase and PP2A phosphatase in male APP/PS1 transgenic mice

BACKGROUND AND PURPOSE

Overexpression of astrocytic lactoferrin (Lf) was observed in the brain of Alzheimer's disease (AD) patients, whereas the role of astrocytic Lf in AD progression remains unexplored. In this study, we aimed to evaluate the effects of astrocytic Lf on AD progression.

EXPERIMENTAL APPROACH

Male APP/PS1 mice with astrocytes overexpressing human Lf were developed to evaluate the effects of astrocytic Lf on AD progression. N2a-sw cells also were employed to further uncover the mechanism of astrocytic Lf on β-amyloid (Aβ) production.

KEY RESULTS

Astrocytic Lf overexpression increased protein phosphatase 2A (PP2A) activity and reduced amyloid precursor protein (APP) phosphorylation, Aβ burden and tau hyperphosphorylation in APP/PS1 mice. Mechanistically, astrocytic Lf overexpression promoted the uptake of astrocytic Lf into neurons in APP/PS1 mice, and conditional medium from astrocytes overexpressing Lf inhibited p-APP (Thr668) expression in N2a-sw cells. Furthermore, recombinant human Lf (hLf) significantly enhanced PP2A activity and inhibited p-APP expression, whereas inhibition of p38 or PP2A activities abrogated the hLf-induced p-APP down-regulation in N2a-sw cells. Additionally, hLf promoted the interaction of p38 and PP2A via p38 activation, thereby enhancing PP2A activity, and low-density lipoprotein receptor-related protein 1 (LRP1) knockdown significantly reversed the hLf-induced p38 activation and p-APP down-regulation.

CONCLUSIONS AND IMPLICATIONS

Our data suggested that astrocytic Lf promoted neuronal p38 activation, via targeting to LRP1, subsequently promoting p38 binding to PP2A to enhance PP2A enzyme activity, which finally inhibited Aβ production via APP dephosphorylation. In conclusion, promoting astrocytic Lf expression may be a potential strategy against AD.

LINKED ARTICLES

This article is part of a themed issue From Alzheimer's Disease to Vascular Dementia: Different Roads Leading to Cognitive Decline. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.6/issuetoc.

Ferroptosis regulation through Nrf2 and implications for neurodegenerative diseases

This article provides an overview of the background knowledge of ferroptosis in the nervous system, as well as the key role of nuclear factor E2-related factor 2 (Nrf2) in regulating ferroptosis. The article takes Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS) as the starting point to explore the close association between Nrf2 and ferroptosis, which is of clear and significant importance for understanding the mechanism of neurodegenerative diseases (NDs) based on oxidative stress (OS). Accumulating evidence links ferroptosis to the pathogenesis of NDs. As the disease progresses, damage to the antioxidant system, excessive OS, and altered Nrf2 expression levels, especially the inhibition of ferroptosis by lipid peroxidation inhibitors and adaptive enhancement of Nrf2 signaling, demonstrate the potential clinical significance of Nrf2 in detecting and identifying ferroptosis, as well as targeted therapy for neuronal loss and mitochondrial dysfunction. These findings provide new insights and possibilities for the treatment and prevention of NDs.

Alzheimer's Disease: An Attempt of Total Recall

This review is an attempt to compile existing hypotheses on the mechanisms underlying the initiation and progression of Alzheimer's disease (AD), starting from sensory impairments observed in AD and concluding with molecular events that are typically associated with the disease. These events include spreading of amyloid plaques and tangles of hyperphosphorylated tau and formation of Hirano and Biondi bodies as well as the development of oxidative stress. We have detailed the degenerative changes that occur in several neuronal populations, including the cholinergic neurons in the nucleus basalis of Meynert, the histaminergic neurons in the tuberomammillary nucleus, the serotonergic neurons in the raphe nuclei, and the noradrenergic neurons in the locus coeruleus. Furthermore, we discuss the potential role of iron accumulation in the brains of subjects with AD in the disease progression which served as a basis for the idea that iron chelation in the brain may mitigate oxidative stress and decelerate disease development. We also draw attention to possible role of sympathetic system and, more specifically, noradrenergic neurons of the superior cervical ganglion in triggering of the disease. We also explore the alternative possibility of compensatory protective changes that may occur in these neurons to support cholinergic function in the forebrain of subjects with AD.

Functionalized Cerium Dioxide Nanoparticles with Antioxidative Neuroprotection for Alzheimer's Disease

Background

Oxidative stress induced reactive oxygen species (ROS) and aggregation of amyloid β (Aβ) in the nervous system are significant contributors to Alzheimer's disease (AD). Cerium dioxide and manganese oxide are known as to be effective and recyclable ROS scavengers with high efficiency in neuroprotection.

Methods

A hollow-structured manganese-doped cerium dioxide nanoparticle (LMC) was synthesized for loading Resveratrol (LMC-RES). The LMC-RES were characterized by TEM, DLS, Zeta potential, and X-ray energy spectrum analysis. We also tested the biocompatibility of LMC-RES and the ability of LMC-RES to cross the blood-brain barrier (BBB). The antioxidant effects of LMC-RES were detected by SH-SY5Y cells. Small animal live imaging was used to detect the distribution of LMC-RES in the brain tissue of AD mice. The cognitive abilities of mice were tested by water maze and nesting experiments. The effects of LMC-RES in reducing oxidative stress and protecting neurons was also explored by histological analysis.

Results

The results showed that LMC-RES had good sustained release effect and biocompatibility. The drug release rate of LMC-RES at 24 hours was 80.9 ± 2.25%. Meanwhile, LMC-RES could cross the BBB and enrich in neurons to exert antioxidant effects. In Aβ-induced SH-SY5Y cells, LMC-RES could inhibits oxidative stress through the Nrf-2/HO-1 signaling pathway. In AD model mice, LMC-RES was able to reduce ROS levels, inhibit Aβ-induced neurotoxicity, and protect neurons and significantly improve cognitive deficits of AD mice after drug administration.

Conclusion

LMC-RES can effectively across the BBB, reduce oxidative stress, inhibit Aβ aggregation, and promote the recovery of neurological function.

Iron homeostasis imbalance and ferroptosis in brain diseases

Brain iron homeostasis is maintained through the normal function of blood-brain barrier and iron regulation at the systemic and cellular levels, which is fundamental to normal brain function. Excess iron can catalyze the generation of free radicals through Fenton reactions due to its dual redox state, thus causing oxidative stress. Numerous evidence has indicated brain diseases, especially stroke and neurodegenerative diseases, are closely related to the mechanism of iron homeostasis imbalance in the brain. For one thing, brain diseases promote brain iron accumulation. For another, iron accumulation amplifies damage to the nervous system and exacerbates patients' outcomes. In addition, iron accumulation triggers ferroptosis, a newly discovered iron-dependent type of programmed cell death, which is closely related to neurodegeneration and has received wide attention in recent years. In this context, we outline the mechanism of a normal brain iron metabolism and focus on the current mechanism of the iron homeostasis imbalance in stroke, Alzheimer's disease, and Parkinson's disease. Meanwhile, we also discuss the mechanism of ferroptosis and simultaneously enumerate the newly discovered drugs for iron chelators and ferroptosis inhibitors.

Iron metabolism: An emerging therapeutic target underlying the anti-Alzheimer's disease effect of ginseng

Finding neuroprotective drugs with fewer side effects and more efficacy has become a major problem as the global prevalence of Alzheimer's disease (AD) rises. Natural drugs have risen to prominence as potential medication candidates. Ginseng has a long history of use in China, and it has a wide range of pharmacological actions that can help with neurological issues. Iron loaded in the brain has been linked to AD pathogenesis. We reviewed the regulation of iron metabolism and its studies in AD and explored how ginseng might regulate iron metabolism and prevent or treat AD. Researchers utilized network pharmacology analysis to identify key factive components of ginseng that protect against AD by regulating ferroptosis. Ginseng and its active ingredients may benefit AD by regulating iron metabolism and targeting ferroptosis genes to inhibit the ferroptosis process. The results present new ideas for ginseng pharmacological studies and initiatives for further research into AD-related drugs. To provide comprehensive information on the neuroprotective use of ginseng to modulate iron metabolism, reveal its potential to treat AD, and provide insights for future research opportunities.

Lactoferrin alleviates Western diet-induced cognitive impairment through the microbiome-gut-brain axis

Lactoferrin (Lf) has been shown to benefit cognitive function in several animal models. To elucidate the underlying mechanisms, male C57BL/6J mice were randomly divided into the control (CON), Western-style diets (WD), lactoferrin (Lf), and Lf + antibiotics (AB) groups. The Lf group was intragastrically administered with Lf, and the Lf + AB group additionally drank a solution with antibiotics. After 16 weeks of intervention, Lf improved the cognitive function as indicated by behavioral tests. Lf also increased the length and curvature of postsynaptic density and upregulated the related protein expression, suggesting improved hippocampal neurons and synapses. Lf suppressed microglia activation and proliferation as revealed by immunofluorescence analysis. Lf decreased the serum levels of pro-inflammatory cytokines and downregulated their protein expressions in the hippocampus region. Lf also inhibited the activation of NF-κB/NLRP3 inflammasomes in the hippocampus. Meanwhile, Lf upregulated the expression of tight junction proteins, and increased the abundance of Bacteroidetes at phylum and Roseburia at genus, which are beneficial for gut barrier and cognitive function. The antibiotics eliminated the effects of long-term Lf intervention on cognitive impairment in the Lf + AB group, suggesting that gut microbiota participated in Lf action. Short-term Lf intervention (2 weeks) prevented WD-induced gut microbiota alteration without inducing behavioral changes, supporting the timing sequence of gut microbiota to the brain. Thus, Lf intervention alleviated cognitive impairment by inhibiting microglial activation and neuroinflammation through the microbiome-gut-brain axis.

The role of microbiome-host interactions in the development of Alzheimer´s disease

Alzheimer`s disease (AD) is the most prevalent cause of dementia. It is often assumed that AD is caused by an aggregation of extracellular beta-amyloid and intracellular tau-protein, supported by a recent study showing reduced brain amyloid levels and reduced cognitive decline under treatment with a beta-amyloid-binding antibody. Confirmation of the importance of amyloid as a therapeutic target notwithstanding, the underlying causes of beta-amyloid aggregation in the human brain, however, remain to be elucidated. Multiple lines of evidence point towards an important role of infectious agents and/or inflammatory conditions in the etiology of AD. Various microorganisms have been detected in the cerebrospinal fluid and brains of AD-patients and have thus been hypothesized to be linked to the development of AD, including Porphyromonas gingivalis (PG) and Spirochaetes. Intriguingly, these microorganisms are also found in the oral cavity under normal physiological conditions, which is often affected by multiple pathologies like caries or tooth loss in AD patients. Oral cavity pathologies are mostly accompanied by a compositional shift in the community of oral microbiota, mainly affecting commensal microorganisms and referred to as 'dysbiosis'. Oral dysbiosis seems to be at least partly mediated by key pathogens such as PG, and it is associated with a pro-inflammatory state that promotes the destruction of connective tissue in the mouth, possibly enabling the translocation of pathogenic microbiota from the oral cavity to the nervous system. It has therefore been hypothesized that dysbiosis of the oral microbiome may contribute to the development of AD. In this review, we discuss the infectious hypothesis of AD in the light of the oral microbiome and microbiome-host interactions, which may contribute to or even cause the development of AD. We discuss technical challenges relating to the detection of microorganisms in relevant body fluids and approaches for avoiding false-positives, and introduce the antibacterial protein lactoferrin as a potential link between the dysbiotic microbiome and the host inflammatory reaction.

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

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

The Role of ERK1/2 Pathway in the Pathophysiology of Alzheimer's Disease: An Overview and Update on New Developments

Alzheimer's disease (AD) is the most common neurodegenerative disorder worldwide. Several findings suggest that correcting the dysregulated signaling pathways may offer a potential therapeutic approach in this disease. Extracellular signal-regulated kinase 1/2 (ERK1/2), a member of the mitogen-activated protein kinase family, plays a major role in regulation of cell proliferation, autophagy process, and protein synthesis. The available literature suggests dysregulated ERK1/2 in AD patients with potential implications in the multifaceted underlying pathologies of AD, including amyloid-β plaque formation, tau phosphorylation, and neuroinflammation. In this regard, in the current review, we aim to summarize the reports on the potential roles of ERK1/2 in AD pathophysiology.

Ferroptosis: a potential therapeutic target for Alzheimer's disease

The most prevalent dementia-causing neurodegenerative condition is Alzheimer's disease (AD). The aberrant buildup of amyloid β and tau hyperphosphorylation are the two most well-known theories about the mechanisms underlying AD development. However, a significant number of pharmacological clinical studies conducted around the world based on the two aforementioned theories have not shown promising outcomes, and AD is still not effectively treated. Ferroptosis, a non-apoptotic programmed cell death defined by the buildup of deadly amounts of iron-dependent lipid peroxides, has received more attention in recent years. A wealth of data is emerging to support the role of iron in the pathophysiology of AD. Cell line and animal studies applying ferroptosis modulators to the treatment of AD have shown encouraging results. Based on these studies, we describe in this review the underlying mechanisms of ferroptosis; the role that ferroptosis plays in AD pathology; and summarise some of the research advances in the treatment of AD with ferroptosis modulators. We hope to contribute to the clinical management of AD.

Insight into the potential role of ferroptosis in neurodegenerative diseases

Ferroptosis is a newly discovered way of programmed cell death, mainly caused by the accumulation of iron-dependent lipid peroxides in cells, which is morphologically, biochemically and genetically different from the previously reported apoptosis, necrosis and autophagy. Studies have found that ferroptosis plays a key role in the occurrence and development of neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease and vascular dementia, which suggest that ferroptosis may be involved in regulating the progression of neurodegenerative diseases. At present, on the underlying mechanism of ferroptosis in neurodegenerative diseases is still unclear, and relevant research is urgently needed to clarify the regulatory mechanism and provide the possibility for the development of agents targeting ferroptosis. This review focused on the regulatory mechanism of ferroptosis and its various effects in neurodegenerative diseases, in order to provide reference for the research on ferroptosis in neurodegenerative diseases.

Iron and Alzheimer's Disease: From Pathology to Imaging

Alzheimer's disease (AD) is a debilitating brain disorder that afflicts millions worldwide with no effective treatment. Currently, AD progression has primarily been characterized by abnormal accumulations of β-amyloid within plaques and phosphorylated tau within neurofibrillary tangles, giving rise to neurodegeneration due to synaptic and neuronal loss. While β-amyloid and tau deposition are required for clinical diagnosis of AD, presence of such abnormalities does not tell the complete story, and the actual mechanisms behind neurodegeneration in AD progression are still not well understood. Support for abnormal iron accumulation playing a role in AD pathogenesis includes its presence in the early stages of the disease, its interactions with β-amyloid and tau, and the important role it plays in AD related inflammation. In this review, we present the existing evidence of pathological iron accumulation in the human AD brain, as well as discuss the imaging tools and peripheral measures available to characterize iron accumulation and dysregulation in AD, which may help in developing iron-based biomarkers or therapeutic targets for the disease.

The Role of Exosomes as Mediators of Neuroinflammation in the Pathogenesis and Treatment of Alzheimer’s Disease

Alzheimer’s disease (AD) is a common neurodegenerative disease characterized by progressive dementia. Accumulation of β–amyloid peptide 1–42 and phosphorylation of tau protein in the brain are the two main pathological features of AD. However, comprehensive studies have shown that neuroinflammation also plays a crucial role in the pathogenesis of AD. Neuroinflammation is associated with neuronal death and abnormal protein aggregation and promotes the pathological process of β-amyloid peptide 1–42 and tau protein. The inflammatory components associated with AD include glial cells, complement system, cytokines and chemokines. In recent years, some researchers have focused on exosomes, a type of membrane nano vesicles. Exosomes can transport proteins, lipids, microRNAs and other signaling molecules to participate in a variety of signaling pathways for signal transmission or immune response, affecting the activity of target cells and participating in important pathophysiological processes. Therefore, exosomes play an essential role in intercellular communication and may mediate neuroinflammation to promote the development of AD. This paper reviews the occurrence and development of neuroinflammation and exosomes in AD, providing a deeper understanding of the pathogenesis of AD. Furthermore, the role of exosomes in the pathogenesis and treatment of AD is further described, demonstrating their potential as therapeutic targets for neuroinflammation and AD in the future.

Vascular Dysfunction Is Central to Alzheimer's Disease Pathogenesis in APOE e4 Carriers

Alzheimer's disease (AD) is the most common form of dementia and the leading risk factor, after age, is possession of the apolipoprotein E epsilon 4 allele (APOE4). Approximately 50% of AD patients carry one or two copies of APOE4 but the mechanisms by which it confers risk are still unknown. APOE4 carriers are reported to demonstrate changes in brain structure, cognition, and neuropathology, but findings have been inconsistent across studies. In the present study, we used multi-modal data to characterise the effects of APOE4 on the brain, to investigate whether AD pathology manifests differently in APOE4 carriers, and to determine if AD pathomechanisms are different between carriers and non-carriers. Brain structural differences in APOE4 carriers were characterised by applying machine learning to over 2000 brain MRI measurements from 33,384 non-demented UK biobank study participants. APOE4 carriers showed brain changes consistent with vascular dysfunction, such as reduced white matter integrity in posterior brain regions. The relationship between APOE4 and AD pathology was explored among the 1260 individuals from the Religious Orders Study and Memory and Aging Project (ROSMAP). APOE4 status had a greater effect on amyloid than tau load, particularly amyloid in the posterior cortical regions. APOE status was also highly correlated with cerebral amyloid angiopathy (CAA). Bulk tissue brain transcriptomic data from ROSMAP and a similar dataset from the Mount Sinai Brain Bank showed that differentially expressed genes between the dementia and non-dementia groups were enriched for vascular-related processes (e.g., "angiogenesis") in APOE4 carriers only. Immune-related transcripts were more strongly correlated with AD pathology in APOE4 carriers with some transcripts such as TREM2 and positively correlated with pathology severity in APOE4 carriers, but negatively in non-carriers. Overall, cumulative evidence from the largest neuroimaging, pathology, and transcriptomic studies available suggests that vascular dysfunction is key to the development of AD in APOE4 carriers. However, further studies are required to tease out non-APOE4-specific mechanisms.

The Key Factors Predicting Dementia in Individuals With Alzheimer’s Disease-Type Pathology

Dementia affects millions of individuals worldwide, yet there are no effective treatments. Alzheimer’s disease, the most common form of dementia, is characterized by amyloid and tau pathology with amyloid accumulation thought to precipitate tau pathology, neurodegeneration, and dementia. The Religious Orders Study and Memory and Aging Project (ROSMAP) cohort is a unique resource with quantitative pathology from multiple brain regions, RNA sequencing, and longitudinal cognitive data. Our previous work applying machine learning to the RNA sequencing data identified lactoferrin (LTF) as the gene most predictive of amyloid accumulation with a potential amyloidogenic mechanism identified in vitro and with cell-culture models. In the present study, we examined which pathologies and genes were related to cognitive status (dementia, mild impairment, and no cognitive impairment) and rate of cognitive decline. Tau load in the anterior cingulate and ADAMTS2, encoding a metallopeptidase, were the respective regional pathology and gene most associated with cognitive decline, while PRTN3, encoding a serine protease, was the key protective feature. ADAMTS2, but not PRTN3, was related to amyloid and tau load in the previous study while LTF was not related to cognitive decline here. These findings confirm a general relationship between tau pathology and dementia, show the specific importance of tau pathology in the anterior cingulate cortex and identify ADAMTS2 as a potential target for slowing cognitive decline.

Iron Dyshomeostasis and Ferroptosis: A New Alzheimer’s Disease Hypothesis?

Iron plays a crucial role in many physiological processes of the human body, but iron is continuously deposited in the brain as we age. Early studies found iron overload is directly proportional to cognitive decline in Alzheimer’s disease (AD). Amyloid precursor protein (APP) and tau protein, both of which are related to the AD pathogenesis, are associated with brain iron metabolism. A variety of iron metabolism-related proteins have been found to be abnormally expressed in the brains of AD patients and mouse models, resulting in iron deposition and promoting AD progression. Amyloid β (Aβ) and hyperphosphorylated tau, two pathological hallmarks of AD, can also promote iron deposition in the brain, forming a vicious cycle of AD development-iron deposition. Iron deposition and the subsequent ferroptosis has been found to be a potential mechanism underlying neuronal loss in many neurodegenerative diseases. Iron chelators, antioxidants and hepcidin were found useful for treating AD, which represents an important direction for AD treatment research and drug development in the future. The review explored the deep connection between iron dysregulation and AD pathogenesis, discussed the potential of new hypothesis related to iron dyshomeostasis and ferroptosis, and summarized the therapeutics capable of targeting iron, with the expectation to draw more attention of iron dysregulation and corresponding drug development.

In Vitro Methodologies to Study the Role of Advanced Glycation End Products (AGEs) in Neurodegeneration

Advanced glycation end products (AGEs) can be present in food or be endogenously produced in biological systems. Their formation has been associated with chronic neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, and amyotrophic lateral sclerosis. The implication of AGEs in neurodegeneration is related to their ability to bind to AGE-specific receptors and the ability of their precursors to induce the so-called “dicarbonyl stress”, resulting in cross-linking and protein damage. However, the mode of action underlying their role in neurodegeneration remains unclear. While some research has been carried out in observational clinical studies, further in vitro studies may help elucidate these underlying modes of action. This review presents and discusses in vitro methodologies used in research on the potential role of AGEs in neuroinflammation and neurodegeneration. The overview reveals the main concepts linking AGEs to neurodegeneration, the current findings, and the available and advisable in vitro models to study their role. Moreover, the major questions regarding the role of AGEs in neurodegenerative diseases and the challenges and discrepancies in the research field are discussed.

Synapses, Microglia, and Lipids in Alzheimer's Disease

Alzheimer's disease (AD) is characterised by synaptic dysfunction accompanied by the microscopically visible accumulation of pathological protein deposits and cellular dystrophy involving both neurons and glia. Late-stage AD shows pronounced loss of synapses and neurons across several differentially affected brain regions. Recent studies of advanced AD using post-mortem brain samples have demonstrated the direct involvement of microglia in synaptic changes. Variants of the Apolipoprotein E and Triggering Receptors Expressed on Myeloid Cells gene represent important determinants of microglial activity but also of lipid metabolism in cells of the central nervous system. Here we review evidence that may help to explain how abnormal lipid metabolism, microglial activation, and synaptic pathophysiology are inter-related in AD.

A Bioinformatics Perspective on the Dysregulation of Ferroptosis and Ferroptosis-related Immune Cell Infiltration in Alzheimer's Disease

Alzheimer's disease (AD) is the most prevalent dementia worldwide, but its pathophysiology and molecular events remain unknown. Herein, we first analyzed the differential expression pattern of patients' AD hippocampus through gene expression array data from the GEO database. Notch2nl, TGFB1I1, and LTF were up-regulated in AD patients, while ARPC1A, CHGB, and MPV17 down-regulated. Second, dysregulation of ferroptosis related genes was demonstrated from our data: PCBP2 and FTL significantly up-significant in AD hippocampus, while VDAC2, LPCAT3, GSS, ACSL4, and ACSL6 significantly down-regulated. The protein-protein interactions (PPI) network revealed that FTL was involved in iron metabolism and utilization, while ACSL4 and ACSL6 were involved in a polyunsaturated fatty acids metabolism network. Gene correlation analysis on differential expressed genes (DEGs) indicated that ferroptosis regulates a series of biological processes and pathways related to AD pathogenesis. Third, ferroptosis-related DEGs regulated the immune cell infiltration pattern in the AD hippocampus, characterized by decreased memory B cells, increased memory resting CD4⁺ T cells, memory activated CD4⁺ T cells, and resting NK cells. The altered expression of ferroptosis-related DEGs affected the infiltration of specific immune cell types. The model constructed by the seven ferroptosis-related differential genes may accurately predict the outcome of AD occurrence. Finally, qPCR validation on these ferroptosis-related DEGs in APPswe/PSEN1dE9 mice confirmed the dysregulated expression of Pcbp2, FTL, GSS, and ACSL4 in the AD hippocampus and forebrain. In conclusion, our results supported the conception that the AD brain revealed dysregulated ferroptosis and immune cell infiltration.