Tau exacerbates excitotoxic brain damage in an animal model of stroke

Anti-cis P-tau attenuates tauopathy and enhances cognitive function following global cerebral ischemia in mice

Global cerebral ischemia/reperfusion (GCI/R) induces widespread neuronal degeneration, accompanied by tauopathy in the hippocampus and profound cognitive impairment. Tau, a microtubule-associated protein highly expressed in neurons, becomes neurotoxic upon hyperphosphorylation, disrupting mitochondrial integrity and destabilizing microtubule architecture. Despite extensive efforts, no practical therapeutic approach has emerged to counter tau-related pathology. This study established a murine GCI/R model using three cycles of bilateral common carotid artery occlusion (5 min per cycle) with 5-min reperfusion intervals. The presence of cis P-tau and cognitive deficits in the hippocampus was confirmed following GCI/R. Treatment with a cis P-tau-targeted monoclonal antibody effectively prevented cognitive deterioration and attenuated ultrastructural brain damage. These findings demonstrate that GCI/R promotes pathogenic tau formation and contributes to cognitive dysfunction. Targeting cis P-tau may represent a viable therapeutic strategy to mitigate neurodegeneration and support cognitive recovery following global cerebral ischemic injury.

Proteinopathies and the Neurodegenerative Aftermath of Stroke: Potential Biomarkers and Treatment Targets

Stroke remains a predominant cause of death and long-term disability among adults worldwide. Emerging evidence suggests that proteinopathies, characterized by the aggregation and accumulation of misfolded proteins, may play a significant role in the aftermath of stroke and the progression of neurodegenerative disorders. In this review, we explore preclinical and clinical research on key proteinopathies associated with stroke, including tau, Aβ (amyloid-β), TDP-43 (TAR DNA-binding protein 43), α-synuclein, and UCH-L1 (ubiquitin C-terminal hydrolase-L1). We focus on their potential as biomarkers for recovery management and as novel treatment targets that may enhance neuronal repair and mitigate secondary neurodegeneration. The involvement of these proteinopathies in various aspects of stroke, including neuroinflammation, oxidative stress, neuronal damage, and vascular dysfunction, underscores their potential. However, further investigations are essential to validate the clinical utility of these biomarkers, elucidate the mechanisms connecting proteinopathies to poststroke neurodegeneration, and develop targeted interventions. Identifying specific protein signatures associated with stroke outcomes could facilitate the advancement of precision medicine tailored to individual patient needs, significantly enhancing the quality of life for stroke survivors.

Accelerated Molecular Transportation in the Brain Extracellular Space with 755-nm Light Attenuates Post-Stroke Cognitive Impairment in Rats

Ischemic stroke exacts a heavy toll in death and disability worldwide. After ischemic stroke, the accumulation of pathobiomolecules in the brain extracellular space (ECS) will exacerbate neurological damage and cognitive impairment. Photobiomodulation (PBM) has been demonstrated to improve cognitive function in Alzheimer's disease mouse models by accelerating molecular transportation in the brain ECS. This suggests that PBM may have a potential role in the accumulation of pathobiomolecules in the brain ECS following ischemic stroke. In this study, we developed a PBM therapy apparatus with custom parameters. By evaluating the treatment effect, we identified that 755 nm was the optimal light wavelength for ischemic stroke in rats with transient middle cerebral artery occlusion/reperfusion. Extracellular diffusion and interstitial fluid (ISF) drainage were measured using a tracer-based magnetic resonance imaging method. Our results showed that PBM accelerated molecular transportation in the brain ECS and ISF drainage, promoting the clearance of pro-inflammatory cytokines and reducing the deposition of pathological proteins. Consequently, the infarct volume decreased and neurological cognitive function was improved. Besides, the acceleration of ISF drainage was achieved by reducing expression and restoring polarization of aquaporin 4 (AQP4) in the peri-infarct area. In summary, we demonstrated that PBM could alleviate ischemia-reperfusion injury and prevent post-stroke cognitive impairment by accelerating molecular transportation in the brain ECS, paving a pathway for ischemic stroke treatment via the light-ECS interaction.

Unraveling the dual role of bilirubin in neurological Diseases: A Comprehensive exploration of its neuroprotective and neurotoxic effects

Neurodegenerative disorders are characterized by a progressive loss of neurons, causing substantial deficits in motor and cognitive functioning. Bilirubin is a yellow by-product of heme, existing in two primary isoforms namely unconjugated and conjugated, while initially produced unconjugated isomer is lipophilic and cytotoxic in nature. At physiological levels, bilirubin has an important role in brain function by acting as a powerful antioxidant, preventing brain tissues from oxidative damage by eliminating reactive oxygen species (ROS). Additionally, it contributes to immune regulation through microglial activation, cytokine release, complement system interception, fragment crystallization (Fc) receptor modulation, and major histocompatibility complex (MHC II) expression modification, which lower the risk of inflammatory and autoimmune reactions in the central nervous system (CNS). As per the literature, serum bilirubin concentrations are associated with CNS diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), ischemic stroke, hemorrhagic stroke, traumatic brain injury (TBI), multiple sclerosis (MS), epilepsy, schizophrenia and kernicterus spectrum disorder (KSD), which causes neuronal damage, especially in regions like the basal ganglia and cerebellum, which causes movement abnormalities and cognitive deficits. The aim of this article is to explore the dual role of bilirubin as neuroprotective and neurotoxic, essential for establishing effective therapeutic outcomes for neurodegenerative diseases by looking at its cellular mechanisms and discussing how bilirubin's antioxidant properties can shield neurons and, in some situations, may induce oxidative stress and apoptosis.

Future Perspectives of NMDAR in CNS Disorders

Neurodegenerative diseases such as Alzheimer's and Parkinson's diseases are among the leading causes of physical and cognitive disability across the globe. Fifty million people worldwide suffer these diseases, and that number is expected to rise as the population ages. Ictus is another pathology that also courses with neurodegeneration and is a leading cause of mortality and long-term disability in developed countries. Schizophrenia is not as common as other mental disorders, affecting approximately 24 million people worldwide. All these disorders have in common that still there is not an effective pharmacological treatment to cure them. The N-methyl-D-aspartate (NMDA) receptor (NMDAR) has attracted attention as a potential therapeutic target due to its important role in learning and memory and also due to its implication in excitotoxicity processes. Some drugs targeting NMDARs are already being used to treat symptoms of disorders affecting the central nervous system (CNS). Here, we aim to review the implications of NMDAR in these CNS pathologies, its role as a potential therapeutic target, and the future perspectives for developing new treatments focused on these receptors.

NO-releasing double-crosslinked responsive hydrogels accelerate the treatment and repair of ischemic stroke

Stroke is a global disease that seriously threatens human life. The pathological mechanisms of ischemic stroke include neuroinflammation, oxidative stress, and the destruction of blood vessels at the lesion site. Here, a biocompatible in situ hydrogel platform was designed to target multiple pathogenic mechanisms post-stroke, including anti-inflammation, anti-oxidant, and promotion of angiogenesis. Double-crosslinked responsive multifunctional hydrogels could quickly respond to the pathological microenvironment of the ischemic damage site and mediate the delivery of nitric oxide (NO) and ISO-1 (inhibitor of macrophage migration inhibitory factor, MIF). The hydrogel demonstrated good biocompatibility and could scavenge reactive oxygen species (ROS) and inflammatory cytokines, such as interleukin-6 (IL-6), interleukin-10 (IL-10), and MIF. In a mouse stroke model, hydrogels, when situated within the microenvironment of cerebral infarction characterized by weak acidity and elevated ROS release, would release anti-inflammatory nanoparticles rapidly that exert an anti-inflammatory effect. Concurrently, NO was sustained release to facilitate angiogenesis and provide neuroprotective effects. Neurological function was significantly improved in treated mice as assessed by the modified neurological severity score, rotarod test, and open field test. These findings indicate that the designed hydrogel held promise for sustained delivery of NO and ISO-1 to alleviate cerebral ischemic injury by responding to the brain's pathological microenvironment.

Extracellular cold-inducible RNA-binding protein in CNS injury: molecular insights and therapeutic approaches

Central nervous system (CNS) injuries, such as ischemic stroke (IS), intracerebral hemorrhage (ICH) and traumatic brain injury (TBI), are a significant global burden. The complex pathophysiology of CNS injury is comprised of primary and secondary injury. Inflammatory secondary injury is incited by damage-associated molecular patterns (DAMPs) which signal a variety of resident CNS cells and infiltrating immune cells. Extracellular cold-inducible RNA-binding protein (eCIRP) is a DAMP which acts through multiple immune and non-immune cells to promote inflammation. Despite the well-established role of eCIRP in systemic and sterile inflammation, its role in CNS injury is less elucidated. Recent literature suggests that eCIRP is a pleiotropic inflammatory mediator in CNS injury. eCIRP is also being evaluated as a clinical biomarker to indicate prognosis in CNS injuries. This review provides a broad overview of CNS injury, with a focus on immune-mediated secondary injury and neuroinflammation. We then review what is known about eCIRP in CNS injury, and its known mechanisms in both CNS and non-CNS cells, identifying opportunities for further study. We also explore eCIRP's potential as a prognostic marker of CNS injury severity and outcome. Next, we provide an overview of eCIRP-targeting therapeutics and suggest strategies to develop these agents to ameliorate CNS injury. Finally, we emphasize exploring novel molecular mechanisms, aside from neuroinflammation, by which eCIRP acts as a critical mediator with significant potential as a therapeutic target and prognostic biomarker in CNS injury.

Biomarkers of mature neuronal differentiation and related diseases

The nervous system regulates perception, cognition and behavioral responses by serving as the body's primary communication system for receiving, regulating and transmitting information. Neurons are the fundamental structures and units of the nervous system. Their differentiation and maturation processes rely on the expression of specific biomarkers. Neuron-specific intracellular markers can be used to determine the degree of neuronal maturation. Neuronal cytoskeletal proteins dictate the shape and structure of neurons, while synaptic plasticity and signaling processes are intricately associated with neuronal synaptic markers. Furthermore, abnormal expression levels of biomarkers can serve as diagnostic indicators for nervous system diseases. This article reviews the markers of mature neuronal differentiation and their relationship with nervous system diseases.

Cellular and pathological functions of tau

Tau protein is involved in various cellular processes, including having a canonical role in binding and stabilization of microtubules in neurons. Tauopathies are neurodegenerative diseases marked by the abnormal accumulation of tau protein aggregates in neurons, as seen, for example, in conditions such as frontotemporal dementia and Alzheimer disease. Mutations in tau coding regions or that disrupt tau mRNA splicing, tau post-translational modifications and cellular stress factors (such as oxidative stress and inflammation) increase the tendency of tau to aggregate and interfere with its clearance. Pathological tau is strongly implicated in the progression of neurodegenerative diseases, and the propagation of tau aggregates is associated with disease severity. Recent technological advancements, including cryo-electron microscopy and disease models derived from human induced pluripotent stem cells, have increased our understanding of tau-related pathology in neurodegenerative conditions. Substantial progress has been made in deciphering tau aggregate structures and the molecular mechanisms that underlie protein aggregation and toxicity. In this Review, we discuss recent insights into the diverse cellular functions of tau and the pathology of tau inclusions and explore the potential for therapeutic interventions.

Molecular Insights into Tau Pathology and its Therapeutic Strategies in Alzheimer's Disease

Alzheimer's disease (AD) is the most common cause of dementia. The two major hallmarks of this disease are extracellular amyloid plaques and intracellular neurofibrillary tangles in the brain, accompanied by loss of neurons and synapses. The plaques and tangles mainly consist of amyloid-β (Aβ) and tau protein, respectively. Most of the therapeutic strategies for AD to date have focused on Aβ. However, there is still no effective therapy available. In recent years, the clinical therapeutic failure of targeting Aβ pathology has resulted in increased interest towards tau-based therapeutics. In the current review, we focus on the research progress regarding the pathological mechanisms of tau protein in this disease and discuss tau-targeting therapeutic strategies.

Interactions Between Ferroptosis and Oxidative Stress in Ischemic Stroke

Ischemic stroke is a devastating condition that occurs due to the interruption of blood flow to the brain, resulting in a range of cellular and molecular changes. In recent years, there has been growing interest in the role of ferroptosis, a newly identified form of regulated cell death, in ischemic stroke. Ferroptosis is driven by the accumulation of lipid peroxides and is characterized by the loss of membrane integrity. Additionally, oxidative stress, which refers to an imbalance between prooxidants and antioxidants, is a hallmark of ischemic stroke and significantly contributes to the pathogenesis of the disease. In this review, we explore the interactions between ferroptosis and oxidative stress in ischemic stroke. We examine the underlying mechanisms through which oxidative stress induces ferroptosis and how ferroptosis, in turn, exacerbates oxidative stress. Furthermore, we discuss potential therapeutic strategies that target both ferroptosis and oxidative stress in the treatment of ischemic stroke. Overall, this review highlights the complex interplay between ferroptosis and oxidative stress in ischemic stroke and underscores the need for further research to identify novel therapeutic targets for this condition.

PLP1-Targeting Antisense Oligonucleotides Improve FOXG1 Syndrome Mice

FOXG1 syndrome is a rare neurodevelopmental disorder of the telencephalon, for which there is no cure. Underlying heterozygous pathogenic variants in the Forkhead Box G1 (FOXG1) gene with resulting impaired or loss of FOXG1 function lead to severe neurological impairments. Here, we report a patient with a de novo pathogenic single nucleotide deletion c.946del (p.Leu316Cysfs*10) of the FOXG1 gene that causes a premature protein truncation. To study this variant in vivo, we generated and characterized Foxg1 c946del mice that recapitulate hallmarks of the human disorder. Accordingly, heterozygous Foxg1 c946del mice display neurological symptoms with aberrant neuronal networks and increased seizure susceptibility. Gene expression profiling identified increased oligodendrocyte- and myelination-related gene clusters. Specifically, we showed that expression of the c946del mutant and of other pathogenic FOXG1 variants correlated with overexpression of proteolipid protein 1 (Plp1), a gene linked to white matter disorders. Postnatal administration of Plp1-targeting antisense oligonucleotides (ASOs) in Foxg1 c946del mice improved neurological deficits. Our data suggest Plp1 as a new target for therapeutic strategies mitigating disease phenotypes in FOXG1 syndrome patients.

Enhanced Fyn-tau and NR2B-PSD95 interactions in epileptic foci in experimental models and human epilepsy

Epilepsy and Alzheimer's disease share some common pathologies such as neurodegeneration, seizures and impaired cognition. However, the molecular mechanisms of these changes are still largely unknown. Fyn, a Src-family non-receptor tyrosine kinase (SFK), and its interaction with tau in mediating brain pathology in epilepsy and Alzheimer's disease can be a potential therapeutic target for disease modification. Although Fyn and tau pathology occurs in both Alzheimer's disease and epilepsy, the dynamics of Fyn-tau and PSD95-NR2B interactions affected by seizures and their impact on brain pathology in epilepsy have not been investigated. In this study, we demonstrate a significant increase of Fyn-tau interactions following seizure induction by kainate in both acute and chronic rodent models and in human epilepsy. In the early phase of epileptogenesis, we show increased Fyn/tau/NR2B/PSD95/neuronal nitric oxide synthase complexes after status epilepticus and a postsynaptic increase of phosphorylated tau (pY18 and AT8), Fyn (pSFK-Y416), NMDAR (pNR2B-Y1472) and neuronal nitric oxide synthase. Hippocampal proximity ligation assay and co-immunoprecipitation revealed a sustained increase of Fyn-tau and NR2B-PSD95 complexes/binding in rat chronic epilepsy at 3 months post-status epilepticus. Enhanced Fyn-tau complexes strongly correlated with the frequency of spontaneously recurring convulsive seizures and epileptiform spikes in the chronic epilepsy model. In human epileptic brains, we also identified increased Fyn-tau and NR2B-PSD95 complexes, tau phosphorylation (pY18 and AT8) and Fyn activation (pSFK-Y416), implying the translational and therapeutic potential of these molecular interactions. In tau knockout mice and in rats treated with a Fyn/SFK inhibitor saracatinib, we found a significant reduction of phosphorylated Fyn, tau (AT8 in saracatinib-treated), NR2B and neuronal nitric oxide synthase and their interactions (Fyn-tau and NR2B-PSD95 in saracatinib-treated group; NR2B-PSD95 in tau knockout group). The reduction of Fyn-tau and NR2B-PSD95 interactions in the saracatinib-treated group, in contrast to the vehicle-treated group, correlated with the modification in seizure progression in the rat chronic epilepsy model. These findings from animal models and human epilepsy provide evidence for the role of Fyn-tau and NR2B-PSD95 interactions in seizure-induced brain pathology and suggest that blocking such interactions could modify the progression of epilepsy.

Emerging role of Jumonji domain-containing protein D3 in inflammatory diseases

Jumonji domain-containing protein D3 (JMJD3) is a 2-oxoglutarate-dependent dioxygenase that specifically removes transcriptional repression marks di- and tri-methylated groups from lysine 27 on histone 3 (H3K27me2/3). The erasure of these marks leads to the activation of some associated genes, thereby influencing various biological processes, such as development, differentiation, and immune response. However, comprehensive descriptions regarding the relationship between JMJD3 and inflammation are lacking. Here, we provide a comprehensive overview of JMJD3, including its structure, functions, and involvement in inflammatory pathways. In addition, we summarize the evidence supporting JMJD3's role in several inflammatory diseases, as well as the potential therapeutic applications of JMJD3 inhibitors. Additionally, we also discuss the challenges and opportunities associated with investigating the functions of JMJD3 and developing targeted inhibitors and propose feasible solutions to provide valuable insights into the functional exploration and discovery of potential drugs targeting JMJD3 for inflammatory diseases.

The link between Alzheimer's disease and stroke: A detrimental synergism

Being age-related disorders, both Alzheimer's disease (AD) and stroke share multiple risk factors, such as hypertension, smoking, diabetes, and apolipoprotein E (APOE) Ɛ4 genotype, and coexist in patients. Accumulation of amyloid-β plaques and neurofibrillary tangled impair cognitive potential, leading to AD. Blocked blood flow in the neuronal tissues, causes neurodegeneration and cell death in stroke. AD is commonly characterized by cerebral amyloid angiopathy, which significantly elevates the risk of hemorrhagic stroke. Patients with AD and stroke have been both reported to exhibit greater cognitive impairment, followed by multiple pathophysiological mechanisms shared between the two. The manuscript aims to elucidate the relationship between AD and stroke, as well as the common pathways and risk factors while understanding the preventive therapies that might limit the negative impacts of this correlation, with diagnostic modalities and current AD treatments. The authors provide a comprehensive review of the link and aid the healthcare professionals to identify suitable targets and risk factors, that may retard cognitive decline and neurodegeneration in patients. However, more intricate research is required in this regard and an interdisciplinary approach that would target both the vascular and neurodegenerative factors would improve the quality of life in AD patients.

Remodeling brain pathological microenvironment to lessen cerebral ischemia injury by multifunctional injectable hydrogels

Ischemia stroke is one of the leading causes of death and disability worldwide. Owing to the limited delivery efficiency to the brain caused by the blood-brain barrier (BBB) and off-target effects of systemic treatment, it is crucial to develop an in situ drug delivery system to improve the therapeutic effect in ischemic stroke. Briefly, we report a multifunctional in situ hydrogel delivery system for the co-delivery of reactive oxygen species (ROS)-responsive nanoparticles loaded with atorvastatin calcium (DSPE-se-se-PEG@AC NPs) and β-nerve growth factor (NGF), which is expected to remodel pathological microenvironment for improving cerebral ischemia injury. The in vitro results exhibited the multifunctional hydrogel scavenged oxygen-glucose deprivation (OGD)-induced free radical, rescued the mitochondrial function, and maintained the survival and function of neurons, hence reducing neuronal apoptosis and neuroinflammation, consequently relieving ischemia injury in hippocampal neurons cell line (HT22). In the rat ischemia stroke model, the hydrogel significantly minified cerebral infarction by regulating inflammatory response, saving apoptotic neurons, and promoting angiogenesis and neurogenesis. Besides, the hydrogel distinctly improved the rats' neurological deficits after cerebral ischemia injury over the long-term observation. In conclusion, the in-situ hydrogel platform has demonstrated promising therapeutic effects in both in vitro and in vivo studies, indicating its potential as a new and effective therapy.

Huanglian Jiedu decoction alleviates neurobehavioral damage in mice with chronic alcohol exposure through the RAS-RAF-MEK-ERK pathway

Objective

Long-term alcohol consumption can cause organic damage to the brain, resulting in mental and nervous system abnormalities and intellectual impairment. Huanglian Jiedu decoction (HLJDD) is the classic representative of clearing heat and detoxifying. This study aimed to explore the effects and possible mechanisms of HLJDD on brain injury in chronic alcohol-exposed mice.

Methods

The alcohol-exposed mice were treated with different doses of HLJDD to observe behavioral changes, hippocampal Aβ1-42 deposition, number and ultrastructural changes of neurons in the hippocampus and prefrontal cortex, and expressions of synaptic proteins. On this basis, transcriptome sequencing was used to analyze the differentially expressed genes in different treatment groups, and functional enrichment analysis was performed. Then, WB and RT-PCR were used to verify the expression of the pathway.

Results

Chronic alcohol exposure reduced body weight in mice, led to motor cognitive impairment, increased Aβ1-42 in the hippocampus, decreased the number of neurons in the hippocampus and prefrontal cortex, and the expression of PSD95 and SYN in the hippocampus. HLJDD significantly improved the cognitive dysfunction of mice and alleviated the damage of the hippocampus and prefrontal cortex. Transcriptome sequencing results showed that the regulatory effects of HLJDD on chronic alcohol-exposed mice may be related to the RAS pathway. Further experiments confirmed that chronic alcohol exposure caused a significant increase in protein and gene expressions of the RAS-RAF-MEK-ERK pathway in mouse, and this activation was reversed by HLJDD.

Conclusion

HLJDD may ameliorate brain damage caused by chronic alcohol exposure by regulating the RAS-RAF-MEK-ERK pathway.

Targeting 14-3-3θ-mediated TDP-43 pathology in amyotrophic lateral sclerosis and frontotemporal dementia mice

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are characterized by cytoplasmic deposition of the nuclear TAR-binding protein 43 (TDP-43). Although cytoplasmic re-localization of TDP-43 is a key event in the pathogenesis of ALS/FTD, the underlying mechanisms remain unknown. Here, we identified a non-canonical interaction between 14-3-3θ and TDP-43, which regulates nuclear-cytoplasmic shuttling. Neuronal 14-3-3θ levels were increased in sporadic ALS and FTD with TDP-43 pathology. Pathogenic TDP-43 showed increased interaction with 14-3-3θ, resulting in cytoplasmic accumulation, insolubility, phosphorylation, and fragmentation of TDP-43, resembling pathological changes in disease. Harnessing this increased affinity of 14-3-3θ for pathogenic TDP-43, we devised a gene therapy vector targeting TDP-43 pathology, which mitigated functional deficits and neurodegeneration in different ALS/FTD mouse models expressing mutant or non-mutant TDP-43, including when already symptomatic at the time of treatment. Our study identified 14-3-3θ as a mediator of cytoplasmic TDP-43 localization with implications for ALS/FTD pathogenesis and therapy.

Tau reduction with artificial microRNAs modulates neuronal physiology and improves tauopathy phenotypes in mice

Abnormal tau accumulation is the hallmark of several neurodegenerative diseases, named tauopathies. Strategies aimed at reducing tau in the brain are promising therapeutic interventions, yet more precise therapies would require targeting specific nuclei and neuronal subpopulations affected by disease while avoiding global reduction of physiological tau. Here, we developed artificial microRNAs directed against the human MAPT mRNA to dwindle tau protein by engaging the endogenous RNA interference pathway. In human differentiated neurons in culture, microRNA-mediated tau reduction diminished neuronal firing without affecting neuronal morphology or impairing axonal transport. In the htau mouse model of tauopathy, we locally expressed artificial microRNAs in the prefrontal cortex (PFC), an area particularly vulnerable to initiating tau pathology in this model. Tau knockdown prevented the accumulation of insoluble and hyperphosphorylated tau, modulated firing activity of putative pyramidal neurons, and improved glucose uptake in the PFC. Moreover, such tau reduction prevented cognitive decline in aged htau mice. Our results suggest target engagement of designed tau-microRNAs to effectively reduce tau pathology, providing a proof of concept for a potential therapeutic approach based on local tau knockdown to rescue tauopathy-related phenotypes.

Trans- and Cis-Phosphorylated Tau Protein: New Pieces of the Puzzle in the Development of Neurofibrillary Tangles in Post-Ischemic Brain Neurodegeneration of the Alzheimer's Disease-like Type

Recent evidence indicates that experimental brain ischemia leads to dementia with an Alzheimer's disease-like type phenotype and genotype. Based on the above evidence, it was hypothesized that brain ischemia may contribute to the development of Alzheimer's disease. Brain ischemia and Alzheimer's disease are two diseases characterized by similar changes in the hippocampus that are closely related to memory impairment. Following brain ischemia in animals and humans, the presence of amyloid plaques in the extracellular space and intracellular neurofibrillary tangles was revealed. The phenomenon of tau protein hyperphosphorylation is a similar pathological feature of both post-ischemic brain injury and Alzheimer's disease. In Alzheimer's disease, the phosphorylated Thr231 motif in tau protein has two distinct trans and cis conformations and is the primary site of tau protein phosphorylation in the pre-entanglement cascade and acts as an early precursor of tau protein neuropathology in the form of neurofibrillary tangles. Based on the latest publication, we present a similar mechanism of the formation of neurofibrillary tangles after brain ischemia as in Alzheimer's disease, established on trans- and cis-phosphorylation of tau protein, which ultimately influences the development of tauopathy.

A transient protein folding response targets aggregation in the early phase of TDP-43-mediated neurodegeneration

Understanding the mechanisms that drive TDP-43 pathology is integral to combating amyotrophic lateral sclerosis (ALS), frontotemporal lobar degeneration (FTLD) and other neurodegenerative diseases. Here we generated a longitudinal quantitative proteomic map of the cortex from the cytoplasmic TDP-43 rNLS8 mouse model of ALS and FTLD, and developed a complementary open-access webtool, TDP-map ( https://shiny.rcc.uq.edu.au/TDP-map/ ). We identified distinct protein subsets enriched for diverse biological pathways with temporal alterations in protein abundance, including increases in protein folding factors prior to disease onset. This included increased levels of DnaJ homolog subfamily B member 5, DNAJB5, which also co-localized with TDP-43 pathology in diseased human motor cortex. DNAJB5 over-expression decreased TDP-43 aggregation in cell and cortical neuron cultures, and knockout of Dnajb5 exacerbated motor impairments caused by AAV-mediated cytoplasmic TDP-43 expression in mice. Together, these findings reveal molecular mechanisms at distinct stages of ALS and FTLD progression and suggest that protein folding factors could be protective in neurodegenerative diseases.

Multi-Omics Profiling Identifies Microglial Annexin A2 as a Key Mediator of NF-κB Pro-inflammatory Signaling in Ischemic Reperfusion Injury

Cerebral stroke is one of the leading causes of mortality and disability worldwide. Restoring the cerebral circulation following a period of occlusion and subsequent tissue oxygenation leads to reperfusion injury. Cerebral ischemic reperfusion (I/R) injury triggers immune and inflammatory responses, apoptosis, neuronal damage, and even death. However, the cellular function and molecular mechanisms underlying cerebral I/R-induced neuronal injury are incompletely understood. By integrating proteomic, phosphoproteomic, and transcriptomic profiling in mouse hippocampi after cerebral I/R, we revealed that the differentially expressed genes and proteins mainly fall into several immune inflammatory response-related pathways. We identified that Annexin 2 (Anxa2) was exclusively upregulated in microglial cells in response to cerebral I/R in vivo and oxygen-glucose deprivation and reoxygenation (OGD/R) in vitro. RNA-seq analysis revealed a critical role of Anxa2 in the expression of inflammation-related genes in microglia via the NF-κB signaling. Mechanistically, microglial Anxa2 is required for nuclear translocation of the p65 subunit of NF-κB and its transcriptional activity upon OGD/R in BV2 microglial cells. Anxa2 knockdown inhibited the OGD/R-induced microglia activation and markedly reduced the expression of pro-inflammatory factors, including TNF-α, IL-1β, and IL-6. Interestingly, conditional medium derived from Anxa2-depleted BV2 cell cultures with OGD/R treatment alleviated neuronal death in vitro. Altogether, our findings revealed that microglia Anxa2 plays a critical role in I/R injury by regulating NF-κB inflammatory responses in a non-cell-autonomous manner, which might be a potential target for the neuroprotection against cerebral I/R injury.

HuR deficiency abrogated the enhanced NLRP3 signaling in experimental ischemic stroke

Human antigen R (HuR) is a universally expressed RNA-binding protein that plays an essential role in governing the fate of mRNA transcripts. Accumulating evidence indicated that HuR is involved in the development and functions of several cell types. However, its role in cerebral ischemia/reperfusion injury (CIRI) remains unclear. In this study, we found that HuR was significantly upregulated after CIRI. Moreover, we found that silencing HuR could inhibit the inflammatory response of microglia and reduce the damage to neurons caused by oxygen-glucose deprivation/reperfusion treatment. In vivo, we found that microglial HuR deficiency significantly ameliorated CIRI and reduced NLRP3-mediated inflammasome activation. Mechanistically, we found that HuR could regulate NLRP3 mRNA stability by binding to the AU-rich element (ARE) region within the 3' untranslated region (UTR) of NLRP3 mRNA. In addition, we found that the upregulation of HuR was dependent on the upregulation of NADPH oxidase-mediated ROS accumulation. Collectively, our studies revealed that HuR could regulate NLRP3 expression and that HuR deficiency abrogated the enhanced NLRP3 signaling in experimental ischemic stroke. Targeting HuR may be a novel therapeutic strategy for cerebral ischemic stroke treatment.

Apoptosis, Autophagy, and Mitophagy Genes in the CA3 Area in an Ischemic Model of Alzheimer's Disease with 2-Year Survival

Background

Currently, no evidence exists on the expression of apoptosis (CASP3), autophagy (BECN1), and mitophagy (BNIP3) genes in the CA3 area after ischemia with long-term survival.

Objective

The goal of the paper was to study changes in above genes expression in CA3 area after ischemia in the period of 6-24 months.

Methods

In this study, using quantitative RT-PCR, we present the expression of genes associated with neuronal death in a rat ischemic model of Alzheimer's disease.

Results

First time, we demonstrated overexpression of the CASP3 gene in CA3 area after ischemia with survival ranging from 0.5 to 2 years. Overexpression of the CASP3 gene was accompanied by a decrease in the activity level of the BECN1 and BNIP3 genes over a period of 0.5 year. Then, during 1-2 years, BNIP3 gene expression increased significantly and coincided with an increase in CASP3 gene expression. However, BECN1 gene expression was variable, increased significantly at 1 and 2 years and was below control values 1.5 years post-ischemia.

Conclusions

Our observations suggest that ischemia with long-term survival induces neuronal death in CA3 through activation of caspase 3 in cooperation with the pro-apoptotic gene BNIP3. This study also suggests that the BNIP3 gene regulates caspase-independent pyramidal neuronal death post-ischemia. Thus, caspase-dependent and -independent death of neuronal cells occur post-ischemia in the CA3 area. Our data suggest new role of the BNIP3 gene in the regulation of post-ischemic neuronal death in CA3. This suggests the involvement of the BNIP3 together with the CASP3 in the CA3 in neuronal death post-ischemia.

Low-dose ionizing radiation promotes motor recovery and brain rewiring by resolving inflammatory response after brain injury and stroke

Traumatic brain injury (TBI) and stroke share a common pathophysiology that worsens over time due to secondary tissue injury caused by sustained inflammatory response. However, studies on pharmacological interventions targeting the complex secondary injury cascade have failed to show efficacy. Here, we demonstrated that low-dose ionizing radiation (LDIR) reduced lesion size and reversed motor deficits after TBI and photothrombotic stroke. Magnetic resonance imaging demonstrated significant reduction of infarct volume in LDIR-treated mice after stroke. Systems-level transcriptomic analysis showed that genes upregulated in LDIR-treated stoke mice were enriched in pathways associated with inflammatory and immune response involving microglia. LDIR induced upregulation of anti-inflammatory- and phagocytosis-related genes, and downregulation of key pro-inflammatory cytokine production. These findings were validated by live-cell assays, in which microglia exhibited higher chemotactic and phagocytic capacities after LDIR. We observed substantial microglial clustering at the injury site, glial scar clearance and reversal of motor deficits after stroke. Cortical microglia/macrophages depletion completely abolished the beneficial effect of LDIR on motor function recovery in stroke mice. LDIR promoted axonal projections (brain rewiring) in motor cortex and recovery of brain activity detected by electroencephalography recordings months after stroke. LDIR treatment delayed by 8 h post-injury still maintained full therapeutic effects on motor recovery, indicating that LDIR is a promising therapeutic strategy for TBI and stroke.

Improving Cognition Without Clearing Amyloid: Effects of Tau and Ultrasound Neuromodulation

Alzheimer's disease is characterized by progressive impairment of neuronal functions culminating in neuronal loss and dementia. A universal feature of dementia is protein aggregation, a process by which a monomer forms intermediate oligomeric assembly states and filaments that develop into end-stage hallmark lesions. In Alzheimer's disease, this is exemplified by extracellular amyloid-β (Aβ) plaques which have been placed upstream of tau, found in intracellular neurofibrillary tangles and dystrophic neurites. This implies causality that can be modeled as a linear activation cascade. When Aβ load is reduced, for example, in response to an anti-Aβ immunotherapy, cognitive functions improve in plaque-forming mice. They also deteriorate less in clinical trial cohorts although real-world clinical benefits remain to be demonstrated. Given the existence of aged humans with unimpaired cognition despite a high plaque load, the central role of Aβ has been challenged. A counter argument has been that clinical symptoms would eventually develop if these aged individuals were to live long enough. Alternatively, intrinsic mechanisms that protect the brain in the presence of pathology may exist. In fact, Aβ toxicity can be abolished by either reducing or manipulating tau (through which Aβ signals), at least in preclinical models. In addition to manipulating steps in this linear pathocascade model, mechanisms of restoring brain reserve can also counteract Aβ toxicity. Low-intensity ultrasound is a neuromodulatory modality that can improve cognitive functions in Aβ-depositing mice without the need for removing Aβ. Together, this highlights a dissociation of Aβ and cognition, with important implications for therapeutic interventions.

Alpha-, Beta-, and Gamma-Secretase, Amyloid Precursor Protein, and Tau Protein Genes in the Hippocampal CA3 Subfield in an Ischemic Model of Alzheimer's Disease with Survival up to 2 Years

Background

Understanding the phenomena underlying the non-selective susceptibility to ischemia of pyramidal neurons in the CA3 is important from the point of view of elucidating the mechanisms of memory loss and the development of dementia.

Objective

The aim of the study was to investigate changes in genes expression of amyloid precursor protein, its cleaving enzymes and tau protein in CA3 post-ischemia with survival of 12-24 months.

Methods

We used an ischemic model of Alzheimer's disease to study the above genes using an RT-PCR protocol.

Results

The expression of the amyloid precursor protein gene was above the control values at all times post-ischemia. The expression of the α-secretase gene also exceeded the control values post-ischemia. The expression of the β-secretase gene increased 12 and 24 months post-ischemia, and 18 months was below control values. Presenilin 1 and 2 genes expression was significantly elevated at all times post-ischemia. Also, tau protein gene expression was significantly elevated throughout the observation period, and peak gene expression was present 12 months post-ischemia.

Conclusions

The study suggests that the genes studied are involved in the non-amyloidogenic processing of amyloid precursor protein. Additionally data indicate that brain ischemia with long-term survival causes damage and death of pyramidal neurons in the CA3 area of the hippocampus in a modified tau protein-dependent manner. Thus defining a new and important mechanism of pyramidal neuronal death in the CA3 area post-ischemia. In addition expression of tau protein gene modification after brain ischemia is useful in identifying ischemic mechanisms occurring in Alzheimer's disease.

Are Ischemic Stroke and Alzheimer's Disease Genetically Consecutive Pathologies?

Complex diseases that affect the functioning of the central nervous system pose a major problem for modern society. Among these, ischemic stroke (IS) holds a special place as one of the most common causes of disability and mortality worldwide. Furthermore, Alzheimer's disease (AD) ranks first among neurodegenerative diseases, drastically reducing brain activity and overall life quality and duration. Recent studies have shown that AD and IS share several common risk and pathogenic factors, such as an overlapping genomic architecture and molecular signature. In this review, we will summarize the genomics and RNA biology studies of IS and AD, discussing the interconnected nature of these pathologies. Additionally, we highlight specific genomic points and RNA molecules that can serve as potential tools in predicting the risks of diseases and developing effective therapies in the future.

Secondary neurodegeneration following Stroke: what can blood biomarkers tell us?

Stroke is one of the leading causes of death and the primary source of disability in adults, resulting in neuronal necrosis of ischemic areas, and in possible secondary degeneration of regions surrounding or distant to the initial damaged area. Secondary neurodegeneration (SNDG) following stroke has been shown to have different pathogenetic origins including inflammation, neurovascular response and cytotoxicity, but can be associated also to regenerative processes. Aside from focal neuronal loss, ipsilateral and contralateral effects distal to the lesion site, disruptions of global functional connectivity and a transcallosal diaschisis have been reported in the chronic stages after stroke. Furthermore, SNDG can be observed in different areas not directly connected to the primary lesion, such as thalamus, hippocampus, amygdala, substantia nigra, corpus callosum, bilateral inferior fronto-occipital fasciculus and superior longitudinal fasciculus, which can be highlighted by neuroimaging techniques. Although the clinical relevance of SNDG following stroke has not been well understood, the identification of specific biomarkers that reflect the brain response to the damage, is of paramount importance to investigate in vivo the different phases of stroke. Actually, brain-derived markers, particularly neurofilament light chain, tau protein, S100b, in post-stroke patients have yielded promising results. This review focuses on cerebral morphological modifications occurring after a stroke, on associated cellular and molecular changes and on state-of-the-art of biomarkers in acute and chronic phase. Finally, we discuss new perspectives regarding the implementation of blood-based biomarkers in clinical practice to improve the rehabilitation approaches and post stroke recovery.

Blood tau-PT217 contributes to the anesthesia/surgery-induced delirium-like behavior in aged mice

INTRODUCTION

Blood phosphorylated tau at threonine 217 (tau-PT217) is a newly established biomarker for Alzheimer's disease and postoperative delirium in patients. However, the mechanisms and consequences of acute changes in blood tau-PT217 remain largely unknown.

METHODS

We investigated the effects of anesthesia/surgery on blood tau-PT217 in aged mice, and evaluated the associated changes in B cell populations, neuronal excitability in anterior cingulate cortex, and delirium-like behavior using positron emission tomography imaging, nanoneedle technology, flow cytometry, electrophysiology, and behavioral tests.

RESULTS

Anesthesia/surgery induced acute increases in blood tau-PT217 via enhanced generation in the lungs and release from B cells. Tau-PT217 might cross the blood-brain barrier, increasing neuronal excitability and inducing delirium-like behavior. B cell transfer and WS635, a mitochondrial function enhancer, mitigated the anesthesia/surgery-induced changes.

DISCUSSION

Acute increases in blood tau-PT217 may contribute to brain dysfunction and postoperative delirium. Targeting B cells or mitochondrial function may have therapeutic potential for preventing or treating these conditions.

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.

Friend or foe: role of pathological tau in neuronal death

Neuronal death is one of the most common pathological hallmarks of diverse neurological diseases, which manifest varying degrees of cognitive or motor dysfunction. Neuronal death can be classified into multiple forms with complicated and unique regulatory signaling pathways. Tau is a key microtubule-associated protein that is predominantly expressed in neurons to stabilize microtubules under physiological conditions. In contrast, pathological tau always detaches from microtubules and is implicated in a series of neurological disorders that are characterized by irreversible neuronal death, such as necrosis, apoptosis, necroptosis, pyroptosis, ferroptosis, autophagy-dependent neuronal death and phagocytosis by microglia. However, recent studies have also revealed that pathological tau can facilitate neuron escape from acute apoptosis, delay necroptosis through its action on granulovacuolar degeneration bodies (GVBs), and facilitate iron export from neurons to block ferroptosis. In this review, we briefly describe the current understanding of how pathological tau exerts dual effects on neuronal death by acting as a double-edged sword in different neurological diseases. We propose that elucidating the mechanism by which pathological tau affects neuronal death is critical for exploring novel and precise therapeutic strategies for neurological disorders.

TDP-43 pathology and functional deficits in wild-type and ALS/FTD mutant cyclin F mouse models

AIMS

Amyotrophic lateral sclerosis (ALS) is characterised by a progressive loss of upper and lower motor neurons leading to muscle weakness and eventually death. Frontotemporal dementia (FTD) presents clinically with significant behavioural decline. Approximately 10% of cases have a known family history, and disease-linked mutations in multiple genes have been identified in FTD and ALS. More recently, ALS and FTD-linked variants have been identified in the CCNF gene, which accounts for an estimated 0.6% to over 3% of familial ALS cases.

METHODS

In this study, we developed the first mouse models expressing either wild-type (WT) human CCNF or its mutant pathogenic variant S621G to recapitulate key clinical and neuropathological features of ALS and FTD linked to CCNF disease variants. We expressed human CCNF WT or CCNFS621G throughout the murine brain by intracranial delivery of adeno-associated virus (AAV) to achieve widespread delivery via somatic brain transgenesis.

RESULTS

These mice developed behavioural abnormalities, similar to the clinical symptoms of FTD patients, as early as 3 months of age, including hyperactivity and disinhibition, which progressively deteriorated to include memory deficits by 8 months of age. Brains of mutant CCNF_S621G mice displayed an accumulation of ubiquitinated proteins with elevated levels of phosphorylated TDP-43 present in both CCNF_WT and mutant CCNF_S621G mice. We also investigated the effects of CCNF expression on interaction targets of CCNF and found elevated levels of insoluble splicing factor proline and glutamine-rich (SFPQ). Furthermore, cytoplasmic TDP-43 inclusions were found in both CCNF_WT and mutant CCNF_S621G mice, recapitulating the key hallmark of FTD/ALS pathology.

CONCLUSIONS

In summary, CCNF expression in mice reproduces clinical presentations of ALS, including functional deficits and TDP-43 neuropathology with altered CCNF-mediated pathways contributing to the pathology observed.

Deregulated Transcription and Proteostasis in Adult mapt Knockout Mouse

Transcriptomics and phosphoproteomics were carried out in the cerebral cortex of B6.Cg-Mapttm1(EGFP)Klt (tau knockout: tau-KO) and wild-type (WT) 12 month-old mice to learn about the effects of tau ablation. Compared with WT mice, tau-KO mice displayed reduced anxiety-like behavior and lower fear expression induced by aversive conditioning, whereas recognition memory remained unaltered. Cortical transcriptomic analysis revealed 69 downregulated and 105 upregulated genes in tau-KO mice, corresponding to synaptic structures, neuron cytoskeleton and transport, and extracellular matrix components. RT-qPCR validated increased mRNA levels of col6a4, gabrq, gad1, grm5, grip2, map2, rab8a, tubb3, wnt16, and an absence of map1a in tau-KO mice compared with WT mice. A few proteins were assessed with Western blotting to compare mRNA expression with corresponding protein levels. Map1a mRNA and protein levels decreased. However, β-tubulin III and GAD1 protein levels were reduced in tau-KO mice. Cortical phosphoproteomics revealed 121 hypophosphorylated and 98 hyperphosphorylated proteins in tau-KO mice. Deregulated phosphoproteins were categorized into cytoskeletal (n = 45) and membrane proteins, including proteins of the synapses and vesicles, myelin proteins, and proteins linked to membrane transport and ion channels (n = 84), proteins related to DNA and RNA metabolism (n = 36), proteins connected to the ubiquitin-proteasome system (UPS) (n = 7), proteins with kinase or phosphatase activity (n = 21), and 22 other proteins related to variegated pathways such as metabolic pathways, growth factors, or mitochondrial function or structure. The present observations reveal a complex altered brain transcriptome and phosphoproteome in tau-KO mice with only mild behavioral alterations.

Tau and GSK-3β are Critical Contributors to α-Synuclein-Mediated Post-Stroke Brain Damage

Post-stroke secondary brain damage is significantly influenced by the induction and accumulation of α-Synuclein (α-Syn). α-Syn-positive inclusions are often present in tauopathies and elevated tau levels and phosphorylation promotes neurodegeneration. Glycogen synthase kinase 3β (GSK-3β) is a known promoter of tau phosphorylation. We currently evaluated the interaction of α-Syn with GSK-3β and tau in post-ischemic mouse brain. Transient focal ischemia led to increased cerebral protein-protein interaction of α-Syn with both GSK-3β and tau and elevated tau phosphorylation. Treatment with a GSK-3β inhibitor prevented post-ischemic tau phosphorylation. Furthermore, α-Syn interaction was observed to be crucial for post-ischemic GSK-3β-dependent tau hyperphosphorylation as it was not seen in α-Syn knockout mice. Moreover, tau knockout mice show significantly smaller brain damage after transient focal ischemia. Overall, the present study indicates that GSK-3β catalyzes the α-Syn-dependent tau phosphorylation and preventing this interaction is crucial to limit post-ischemic secondary brain damage.

Diagnosis of cerebral malaria: Tools to reduce Plasmodium falciparum associated mortality

Cerebral malaria (CM) is a major cause of mortality in Plasmodium falciparum (Pf) infection and is associated with the sequestration of parasitised erythrocytes in the microvasculature of the host's vital organs. Prompt diagnosis and treatment are key to a positive outcome in CM. However, current diagnostic tools remain inadequate to assess the degree of brain dysfunction associated with CM before the window for effective treatment closes. Several host and parasite factor-based biomarkers have been suggested as rapid diagnostic tools with potential for early CM diagnosis, however, no specific biomarker signature has been validated. Here, we provide an updated review on promising CM biomarker candidates and evaluate their applicability as point-of-care tools in malaria-endemic areas.

Treatment of epilepsy using a targeted p38γ kinase gene therapy

Hyperphosphorylated microtubule-associated protein tau has been implicated in dementia, epilepsy, and other neurological disorders. In contrast, site-specific phosphorylation of tau at threonine 205 (T205) by the kinase p38γ was shown to disengage tau from toxic pathways, serving a neuroprotective function in Alzheimer's disease. Using a viral-mediated gene delivery approach in different mouse models of epilepsy, we show that p38γ activity-enhancing treatment reduces seizure susceptibility, restores neuronal firing patterns, reduces behavioral deficits, and ameliorates epilepsy-induced deaths. Furthermore, we show that p38γ-mediated phosphorylation of tau at T205 is essential for this protection in epilepsy, as a lack of this critical interaction reinstates pathological features and accelerates epilepsy in vivo. Hence, our work provides a scope to harness p38γ as a future therapy applicable to acute neurological conditions.

The Inhibition of Zinc Excitotoxicity and AMPK Phosphorylation by a Novel Zinc Chelator, 2G11, Ameliorates Neuronal Death Induced by Global Cerebral Ischemia

AMP-activated protein kinase (AMPK) is necessary for maintaining a positive energy balance and essential cellular processes such as glycolysis, gene transcription, glucose uptake, and several other biological functions. However, brain injury-induced energy and metabolic stressors, such as cerebral ischemia, increase AMPK phosphorylation. Phosphorylated AMPK contributes to excitotoxicity, oxidative, and metabolic problems. Furthermore, brain disease-induced release of zinc from synaptic vesicles contributes to neuronal damage via mechanisms including ROS production, apoptotic cell death, and DNA damage. For this reason, we hypothesized that regulating zinc accumulation and AMPK phosphorylation is critical for protection against global cerebral ischemia (GCI). Through virtual screening based on the structure of AMPK subunit alpha 2, we identified a novel compound, 2G11. In this study, we verified that 2G11 administration has neuroprotective effects via the blocking of zinc translocation and AMPK phosphorylation after GCI. As a result, we demonstrated that 2G11 protected hippocampal neurons against GCI and OGD/R-derived cellular damage. In conclusion, we propose that AMPK inhibition and zinc chelation by 2G11 may be a promising tool for preventing GCI-induced hippocampal neuronal death.

Galangin inhibited ferroptosis through activation of the PI3K/AKT pathway in vitro and in vivo

Ferroptosis is an iron-dependent form of nonapoptotic cell death characterized by the accumulation of lipid peroxides in cells. In recent years, extensive attention has been dedicated to exploring safe and effective natural ferroptosis regulators which can provide novel treatment strategies for ferroptosis-related diseases. This study identified galangin, a natural flavonoid, as an effective inhibitor of ferroptosis, which could increase cell viability in RSL3-inhibited HT1080 cells, decrease levels of lipid ROS and MDA, improve PTGS2 mRNA expression, and enhance the expression of glutathione peroxidase 4 (GPX4). Ferroptosis is widely present in ischemia-reperfusion (IR) injury. This study found that galangin significantly ameliorated the pathological damage of liver tissue in mice with IR, reduced levels of serum ALT, AST, and MDA, and increased the expression of GPX4. The results of RNA-seq exhibited ferroptosis was significant and the PI3K/AKT pathway deserved to explore the inhibition effects of galangin on ferroptosis. Indeed, galangin treatment significantly rescued RSL3-inhibited phosphorylation levels of PI3K, AKT, and CREB proteins, and the ferroptosis inhibitory effects of galangin were counteracted by PI3K inhibitor LY294002. These findings indicated that galangin may exert its anti-ferroptosis effects via activating the PI3K/AKT/CREB signaling pathway and it will hopefully serve as a promising effective measure to attenuate IR injury by inhibiting ferroptosis.

Mitochondrial ferritin alleviates apoptosis by enhancing mitochondrial bioenergetics and stimulating glucose metabolism in cerebral ischemia reperfusion

Oxidative stress and deficient bioenergetics are key players in the pathological process of cerebral ischemia reperfusion injury (I/R). As a mitochondrial iron storage protein, mitochondrial ferritin (FtMt) plays a pivotal role in protecting neuronal cells from oxidative damage under stress conditions. However, the effects of FtMt in mitochondrial function and activation of apoptosis under cerebral I/R are barely understood. In the present study, we found that FtMt deficiency exacerbates neuronal apoptosis via classical mitochondria-depedent pathway and the endoplasmic reticulum (ER) stress pathway in brains exposed to I/R. Conversely, FtMt overexpression significantly inhibited oxygen and glucose deprivation and reperfusion (OGD/R)-induced apoptosis and the activation of ER stress response. Meanwhile, FtMt overexpression rescued OGD/R-induced mitochondrial iron overload, mitochondrial dysfunction, the generation of reactive oxygen species (ROS) and increased neuronal GSH content. Using the Seahorse and O2K cellular respiration analyser, we demonstrated that FtMt remarkably improved the ATP content and the spare respiratory capacity under I/R conditions. Importantly, we found that glucose consumption was augmented in FtMt overexpressing cells after OGD/R insult; overexpression of FtMt facilitated the activation of glucose 6-phosphate dehydrogenase and the production of NADPH in cells after OGD/R, indicating that the pentose-phosphate pathway is enhanced in FtMt overexpressing cells, thus strengthening the antioxidant capacity of neuronal cells. In summary, our results reveal that FtMt protects against I/R-induced apoptosis through enhancing mitochondrial bioenergetics and regulating glucose metabolism via the pentose-phosphate pathway, thus preventing ROS overproduction, and preserving energy metabolism.

Loss of LAMP5 interneurons drives neuronal network dysfunction in Alzheimer's disease

In Alzheimer's disease (AD), where amyloid-β (Aβ) and tau deposits in the brain, hyperexcitation of neuronal networks is an underlying disease mechanism, but its cause remains unclear. Here, we used the Collaborative Cross (CC) forward genetics mouse platform to identify modifier genes of neuronal hyperexcitation. We found LAMP5 as a novel regulator of hyperexcitation in mice, critical for the survival of distinct interneuron populations. Interestingly, synaptic LAMP5 was lost in AD brains and LAMP5 interneurons degenerated in different AD mouse models. Genetic reduction of LAMP5 augmented functional deficits and neuronal network hypersynchronicity in both Aβ- and tau-driven AD mouse models. To this end, our work defines the first specific function of LAMP5 interneurons in neuronal network hyperexcitation in AD and dementia with tau pathology.

Tau target identification reveals NSF-dependent effects on AMPA receptor trafficking and memory formation

Microtubule-associated protein tau is a central factor in Alzheimer's disease and other tauopathies. However, the physiological functions of tau are unclear. Here, we used proximity-labelling proteomics to chart tau interactomes in primary neurons and mouse brains in vivo. Tau interactors map onto pathways of cytoskeletal, synaptic vesicle and postsynaptic receptor regulation and show significant enrichment for Parkinson's, Alzheimer's and prion disease. We find that tau interacts with and dose-dependently reduces the activity of N-ethylmaleimide sensitive fusion protein (NSF), a vesicular ATPase essential for AMPA-type glutamate receptor (AMPAR) trafficking. Tau-deficient (tau-/- ) neurons showed mislocalised expression of NSF and enhanced synaptic AMPAR surface levels, reversible through the expression of human tau or inhibition of NSF. Consequently, enhanced AMPAR-mediated associative and object recognition memory in tau-/- mice is suppressed by both hippocampal tau and infusion with an NSF-inhibiting peptide. Pathologic mutant tau from mouse models or Alzheimer's disease significantly enhances NSF inhibition. Our results map neuronal tau interactomes and delineate a functional link of tau with NSF in plasticity-associated AMPAR-trafficking and memory.

Natural Compounds for SIRT1-Mediated Oxidative Stress and Neuroinflammation in Stroke: A Potential Therapeutic Target in the Future

Stroke is a fatal cerebral vascular disease with a high mortality rate and substantial economic and social costs. ROS production and neuroinflammation have been implicated in both hemorrhagic and ischemic stroke and have the most critical effects on subsequent brain injury. SIRT1, a member of the sirtuin family, plays a crucial role in modulating a wide range of physiological processes, including apoptosis, DNA repair, inflammatory response, and oxidative stress. Targeting SIRT1 to reduce ROS and neuroinflammation might represent an emerging therapeutic target for stroke. Therefore, we conducted the present review to summarize the mechanisms of SIRT1-mediated oxidative stress and neuroinflammation in stroke. In addition, we provide a comprehensive introduction to the effect of compounds and natural drugs on SIRT1 signaling related to oxidative stress and neuroinflammation in stroke. We believe that our work will be helpful to further understand the critical role of the SIRT1 signaling pathway and will provide novel therapeutic potential for stroke treatment.

Cell Death Mechanisms in Cerebral Ischemia-Reperfusion Injury

Ischemic stroke is one of the major causes of morbidity and mortality, affecting millions of people worldwide. Inevitably, the interruption of cerebral blood supply after ischemia may promote a cascade of pathophysiological processes. Moreover, the subsequent restoration of blood flow and reoxygenation may further aggravate brain tissue injury. Although recombinant tissue plasminogen activator (rt-PA) is the only approved therapy for restoring blood perfusion, the reperfusion injury and the narrow therapeutic time window restrict its application for most stroke patients. Increasing evidence indicates that multiple cell death mechanisms are relevant to cerebral ischemia-reperfusion injury, including apoptosis, necrosis, necroptosis, autophagy, pyroptosis, ferroptosis, and so on. Therefore, it is crucial to comprehend various cell death mechanisms and their interactions. In this review, we summarize the various signaling pathways underlying cerebral ischemia-reperfusion injury and elaborate on the crosstalk between the different mechanisms.

Shared pathophysiology: Understanding stroke and Alzheimer's disease

Alzheimer's disease and stroke share several known vascular risk factors. The pathophysiology and whether one predisposes to the other is a topic of ongoing investigation. In this critical review, we highlight what is known about each pathway and the shared potential mechanisms. We offer insight into topics that warrant further investigation. We address topics of both neurodegeneration and secondary cascades. Furthermore, the concept of targeting secondary mechanisms early might be a viable treatment option for ongoing preventative measures. The review is intended to serve as a catalyst for further scientific inquiry into this important topic.

Glutamate excitotoxicity: Potential therapeutic target for ischemic stroke

Glutamate-mediated excitotoxicity is an important mechanism leading to post ischemic stroke damage. After acute stroke, the sudden reduction in cerebral blood flow is most initially followed by ion transport protein dysfunction and disruption of ion homeostasis, which in turn leads to impaired glutamate release, reuptake, and excessive N-methyl-D-aspartate receptor (NMDAR) activation, promoting neuronal death. Despite extensive evidence from preclinical studies suggesting that excessive NMDAR stimulation during ischemic stroke is a central step in post-stroke damage, NMDAR blockers have failed to translate into clinical stroke treatment. Current treatment options for stroke are very limited, and there is therefore a great need to develop new targets for neuroprotective therapeutic agents in ischemic stroke to extend the therapeutic time window. In this review, we highlight recent findings on glutamate release, reuptake mechanisms, NMDAR and its downstream cellular signaling pathways in post-ischemic stroke damage, and review the pathological changes in each link to help develop viable new therapeutic targets. We then also summarize potential neuroprotective drugs and therapeutic approaches for these new targets in the treatment of ischemic stroke.

Tau Acts in Concert With Kinase/Phosphatase Underlying Synaptic Dysfunction

Alzheimer's disease (AD) is characterized by two pathological features: neurofibrillary tangles (NFTs), formed by microtubule-associated protein tau, and abnormal accumulation of amyloid-β (Aβ). Multiple evidence placed synaptic tau as the vital fact of AD pathology, especially at the very early stage of AD. In the present review, we discuss tau phosphorylation, which is critical for the dendritic localization of tau and synaptic plasticity. We review the related kinases and phosphatases implicated in the synaptic function of tau. We also review the synergistic effects of these kinases and phosphatases on tau-associated synaptic deficits. We aim to open a new perspective on the treatment of AD.

Network activity changes in the pathophysiology of Alzheimer's disease: the role of aging and early entorhinal cortex dysfunction

The greatest risk factor for development of the deadly neurodegenerative disorder known as Alzheimer's disease (AD) is advancing age. Currently unknown is what mediates the impact of advanced age on development of AD. Also unknown is what impact activity alterations in the entorhinal cortex (EC) has on the spread of AD pathology such as pathological tau through the brain as AD progresses. This review focuses on evidence in the literature that describes how one potential age-related change, that of glutamate-mediated increases in neuronal activity, may ultimately increase the risk of developing AD and promote the spread of tau pathology in AD-affected brains from the EC to later regions such as the hippocampus and prefrontal cortex. A better understanding of these detrimental alterations may allow for earlier detection of AD, offering a better prognosis for affected individuals.