Deregulated mitochondrial microRNAs in Alzheimer's disease: Focus on synapse and mitochondria

Advanced nano delivery system for stem cell therapy for Alzheimer's disease

Alzheimer's Disease (AD) represents one of the most significant neurodegenerative challenges of our time, with its increasing prevalence and the lack of curative treatments underscoring an urgent need for innovative therapeutic strategies. Stem cells (SCs) therapy emerges as a promising frontier, offering potential mechanisms for neuroregeneration, neuroprotection, and disease modification in AD. This article provides a comprehensive overview of the current landscape and future directions of stem cell therapy in AD treatment, addressing key aspects such as stem cell migration, differentiation, paracrine effects, and mitochondrial translocation. Despite the promising therapeutic mechanisms of SCs, translating these findings into clinical applications faces substantial hurdles, including production scalability, quality control, ethical concerns, immunogenicity, and regulatory challenges. Furthermore, we delve into emerging trends in stem cell modification and application, highlighting the roles of genetic engineering, biomaterials, and advanced delivery systems. Potential solutions to overcome translational barriers are discussed, emphasizing the importance of interdisciplinary collaboration, regulatory harmonization, and adaptive clinical trial designs. The article concludes with reflections on the future of stem cell therapy in AD, balancing optimism with a pragmatic recognition of the challenges ahead. As we navigate these complexities, the ultimate goal remains to translate stem cell research into safe, effective, and accessible treatments for AD, heralding a new era in the fight against this devastating disease.

Panax Quinquefolium Saponins protects neuronal activity by promoting mitophagy in both in vitro and in vivo models of Alzheimer's disease

ETHNOPHARMACOLOGICAL RELEVANCE

In the realm of traditional Chinese medicine, Panax quinquefolius L. has garnered significant attention for its potential to treat various ailments associated with deficiencies, including qi, blood, and kidneys. As its primary bioactive constituent, Panax quinquefolius saponins (PQS) have the potential therapeutic role of Alzheimer's disease (AD) treatment, but with unclear mechanisms of action. Meanwhile, AD is considered as a common dementia disease with kidney insufficiency and deficiency by traditional medicine, and often accompanied by autophagy in modern medical research.

AIM OF THE STUDY

This study aimed to investigate the therapeutic effects of PQS on AD through the regulation of mitophagy.

MATERIALS AND METHODS

The chemical constituents of PQS were characterised using the UPLC-QTOF-MS technique. After that, the HT22 cell line was used to establish the D-galactose-induced cell model, and the SAMP8 mice model of AD was also employed. Cell viability was assessed using the CCK-8 assay, ROS detection, JC-1 staining, Mito-tracker Red and LC3 staining, and Mito-tracker Green and Lyso-tracker Red staining were used to assess levels of mitophagy. The Morris Water Maze (MWM) was used for the experimental evaluation of learning and memory abilities in mice. Subsequently, the mechanism was studied by pathological staining and western blotting.

RESULTS

Fifty-eight triterpenoid saponins were identified from PQS, and PQS alleviated D-galactose-induced HT22 cell death and increased intracellular levels of mitochondrial autophagy-related factors. In vivo, PQS significantly improved cognitive deficits and mitigated AD-like pathological features by activating the mitophagy mechanism. Furthermore, PQS may promote Pink1/Parkin-mediated mitophagy by activating the AMPK/mTOR/ULK1/DRP1 and SIRT1/PGC-1α pathways.

CONCLUSION

In conclusion, PQS have demonstrated the potential to mitigate mitochondrial dysfunction and enhance cognitive function in AD through the activation of mitophagy. This promising strategy holds great promise for the treatment of AD.

Steroidogenic acute regulatory protein mediated variations of gender-specific sex neurosteroids in Alzheimer's disease: Relevance to hormonal and neuronal imbalance

The steroidogenic acute regulatory (StAR) protein mediates the rate-liming step in neuro/steroid biosynthesis. Multifaceted and delicate changes during aging, disrupting hormonal and neuronal homeostasis, constitute human senescence, an inevitable phenomenon that attributes to increased morbidity and mortality. Aging, along with progressive decreases in bioactive neurosteroids, is the primary risk factor for Alzheimer's disease (AD), which preferentially impacts two-thirds of women and one-third of men. AD is neuropathologically characterized by the accumulation of extracellular amyloid-β and intracellular phosphorylated Tau containing neurofibrillary tangles, resulting in dementia. Postmortem brains pertaining to gender-specific AD patients exhibit varied suppression of StAR and sex neurosteroid levels compared with age-matched cognitively healthy subjects, in which the attenuation of StAR is inversely correlated with the AD pathological markers. Interestingly, retinoid signaling upregulates StAR-motivated neurosteroid biosynthesis and reinstates various neurodegenerative vulnerabilities that promote AD pathogenesis. This review summarizes current understanding of StAR-driven alterations of sex neurosteroids in gender-specific AD risks and provides biochemical and molecular insights into therapeutic interventions for preventing and/or alleviating dementia for healthy aging.

Epigenetic biomarkers in Alzheimer's disease: Diagnostic and prognostic relevance

Alzheimer's disease (AD) is a leading cause of cognitive decline in the aging population, presenting a critical need for early diagnosis and effective prognostic tools. Epigenetic modifications, including DNA methylation, histone modifications, and non-coding RNAs, have emerged as promising biomarkers for AD due to their roles in regulating gene expression and potential for reversibility. This review examines the current landscape of epigenetic biomarkers in AD, emphasizing their diagnostic and prognostic relevance. DNA methylation patterns in genes such as APP, PSEN1, and PSEN2 are highlighted for their strong associations with AD pathology. Alterations in DNA methylation at specific CpG sites have been consistently observed in AD patients, suggesting their utility in early detection. Histone modifications, such as acetylation and methylation, also play a crucial role in chromatin remodelling and gene expression regulation in AD. Dysregulated histone acetylation and methylation have been linked to AD progression, making these modifications valuable biomarkers. Non-coding RNAs, including microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), further contribute to the epigenetic regulation in AD. miRNAs can modulate gene expression post-transcriptionally and have been found in altered levels in AD, while lncRNAs can influence chromatin structure and gene expression. The presence of these non-coding RNAs in biofluids like blood and cerebrospinal fluid positions them as accessible and minimally invasive biomarkers. Technological advancements in detecting and quantifying epigenetic modifications have propelled the field forward. Techniques such as next-generation sequencing, bisulfite sequencing, and chromatin immunoprecipitation assays offer high sensitivity and specificity, enabling the detailed analysis of epigenetic changes in clinical samples. These tools are instrumental in translating epigenetic research into clinical practice. This review underscores the potential of epigenetic biomarkers to enhance the early diagnosis and prognosis of AD, paving the way for personalized therapeutic strategies and improved patient outcomes. The integration of these biomarkers into clinical workflows promises to revolutionize AD management, offering hope for better disease monitoring and intervention.

The new perspective of Alzheimer's Disease Research: Mechanism and therapeutic strategy of neuronal senescence

Alzheimer's disease (AD), commonly known as senile dementia, is a neurodegenerative disease with insidious onset and gradually worsening course. The brain is particularly sensitive to senescence, and neuronal senescence is an important risk factor for the occurrence of AD. However, the exact pathogenesis between neuronal senescence and AD has not been fully elucidated so far. Neuronal senescence is characterized by the permanent stagnation of the cell cycle, and the changes in its structure, function, and microenvironment are closely related to the pathogenesis and progression of AD. In recent years, studies such as the Aβ cascade hypothesis and Tau protein phosphorylation have provided new strategies for the therapy of AD, but due to the complexity of the etiology of AD, there are still no effective treatment measures. This article aims to deeply analyze the pathogenesis between AD and neuronal senescence, and sort out various existing therapeutic methods, to provide new ideas and references for the clinical treatment of AD.

Mitochondrial dysfunction as a therapeutic strategy for neurodegenerative diseases: Current insights and future directions

Neurodegenerative diseases, as common diseases in the elderly, tend to become younger due to environmental changes, social development and other factors. They are mainly characterized by progressive loss or dysfunction of neurons in the central or peripheral nervous system, and common diseases include Parkinson's disease, Alzheimer's disease, Huntington's disease and so on. Mitochondria are important organelles for adenosine triphosphate (ATP) production in the brain. In recent years, a large amount of evidence has shown that mitochondrial dysfunction plays a direct role in neurodegenerative diseases, which is expected to provide new ideas for the treatment of related diseases. This review will summarize the main mechanisms of mitochondrial dysfunction in neurodegenerative diseases, as well as collating recent advances in the study of mitochondrial disorders and new therapies.

The Role of Reactive Oxygen Species in Alzheimer's Disease: From Mechanism to Biomaterials Therapy

Alzheimer's disease (AD) is a chronic, insidious, and progressive neurodegenerative disease that remains a clinical challenge for society. The fully approved drug lecanemab exhibits the prospect of therapy against the pathological processes, while debatable adverse events conflict with the drug concentration required for the anticipated therapeutic effects. Reactive oxygen species (ROS) are involved in the pathological progression of AD, as has been demonstrated in much research regarding oxidative stress (OS). The contradiction between anticipated dosage and adverse event may be resolved through targeted transport by biomaterials and get therapeutic effects through pathological progression via regulation of ROS. Besides, biomaterials fix delivery issues by promoting the penetration of drugs across the blood-brain barrier (BBB), protecting the drug from peripheral degradation, and elevating bioavailability. The goal is to comprehensively understand the mechanisms of ROS in the progression of AD disease and the potential of ROS-related biomaterials in the treatment of AD. This review focuses on OS and its connection with AD and novel biomaterials in recent years against AD via OS to inspire novel biomaterial development. Revisiting these biomaterials and mechanisms associated with OS in AD via thorough investigations presents a considerable potential and bright future for improving effective interventions for AD.

Synaptic mitochondria: A crucial factor in the aged hippocampus

Aging is a multifaceted biological process characterized by progressive molecular and cellular damage accumulation. The brain hippocampus undergoes functional deterioration with age, caused by cellular deficits, decreased synaptic communication, and neuronal death, ultimately leading to memory impairment. One of the factors contributing to this dysfunction is the loss of mitochondrial function. In neurons, mitochondria are categorized into synaptic and non-synaptic pools based on their location. Synaptic mitochondria, situated at the synapses, play a crucial role in maintaining neuronal function and synaptic plasticity, whereas non-synaptic mitochondria are distributed throughout other neuronal compartments, supporting overall cellular metabolism and energy supply. The proper function of synaptic mitochondria is essential for synaptic transmission as they provide the energy required and regulate calcium homeostasis at the communication sites between neurons. Maintaining the structure and functionality of synaptic mitochondria involves intricate processes, including mitochondrial dynamics such as fission, fusion, transport, and quality control mechanisms. These processes ensure that mitochondria remain functional, replace damaged organelles, and sustain cellular homeostasis at synapses. Notably, deficiencies in these mechanisms have been increasingly associated with aging and the onset of age-related neurodegenerative diseases. Synaptic mitochondria from the hippocampus are particularly vulnerable to age-related changes, including alterations in morphology and a decline in functionality, which significantly contribute to decreased synaptic activity during aging. This review comprehensively explores the critical roles that mitochondrial dynamics and quality control mechanisms play in preserving synaptic activity and neuronal function. It emphasizes the emerging evidence linking the deterioration of synaptic mitochondria to the aging process and the development of neurodegenerative diseases, highlighting the importance of these organelles from hippocampal neurons as potential therapeutic targets for mitigating cognitive decline and synaptic degeneration associated with aging. The novelty of this review lies in its focus on the unique vulnerability of hippocampal synaptic mitochondria to aging, underscoring their importance in maintaining brain function across the lifespan.

Autophagy-lysosomal pathway impairment and cathepsin dysregulation in Alzheimer's disease

Alzheimer's disease (AD) is characterized by neuronal loss, attributed to amyloid-beta (Aβ) aggregation and accumulation. The autophagy-lysosomal pathway, including cathepsins B and D, is crucial for protein degradation and clearance, but it is impaired in some diseases. This review summarizes current knowledge on the dysregulation of this pathway in AD. Accumulating evidence suggests that Aβ overload impairs autophagy-lysosomal function and cathepsin activity, exacerbating Aβ accumulation and neurodegeneration. However, the precise mechanisms underlying these interactions remain elusive. Despite these challenges, targeting the lysosomal pathway emerges as a promising therapeutic strategy, and a comprehensive understanding of the autophagy-lysosomal system is essential to develop effective interventions for AD.

Mitochondrial modulation treating postoperative cognitive dysfunction neuroprotection via DRP1 inhibition by Mdivi1

This study investigated the role of mitochondrial dynamics in postoperative cognitive dysfunction (POCD) and assessed the therapeutic potential of mitochondrial modulation, particularly through the inhibition of dynamin-related protein 1 (DRP1) with Mdivi-1. Our findings indicated that DRP1 inhibition substantially mitigated neuroinflammation mediated by microglial cells, contributing to improved cognitive function in POCD models. The administration of Mdivi-1 led to a notable decrease in mitochondrial fission, reduced reactive oxygen species (ROS) production, and stabilization of mitochondrial membrane potential, all of which correlate with diminished neuroinflammation, as evidenced by lower NOD-like receptor family pyrin domain containing 3 (NLRP3)/ interleukin-1β (IL-1β) expression in microglial cells. Importantly, Mdivi-1 treatment was also found to enhance synaptic plasticity, increasing synaptic spine density in the hippocampal region of POCD mice. This improvement in mitochondrial health and synaptic integrity was paralleled by enhanced cognitive performance, as demonstrated in Y-maze tests. These results underscored the critical role of mitochondrial dynamics in the pathophysiology of POCD and suggested that targeting mitochondrial dysfunction, specifically through DRP1 inhibition, could be an effective approach for POCD treatment.

NAD+-boosting agent nicotinamide mononucleotide potently improves mitochondria stress response in Alzheimer's disease via ATF4-dependent mitochondrial UPR

Extensive studies indicate that mitochondria dysfunction is pivotal for Alzheimer's disease (AD) pathogenesis; while cumulative evidence suggests that increased mitochondrial stress response (MSR) may mitigate neurodegeneration in AD, explorations to develop a MSR-targeted therapeutic strategy against AD are scarce. We combined cell biology, molecular biology, and pharmacological approaches to unravel a novel molecular pathway by which NAD+-boosting agent nicotinamide mononucleotide (NMN) regulates MSR in AD models. Here, we report dyshomeostasis plasma UPRmt-mitophagy-mediated MSR profiles in AD patient samples. NMN restores NAD+ metabolic profiles and improves MSR through the ATF4-dependent UPRmt pathway in AD-related cross-species models. At the organismal level, NAD+ repletion with NMN supplementation ameliorates mitochondrial proteotoxicity, decreases hippocampal synaptic disruption, decreases neuronal loss, and brain atrophy in mice model of AD. Remarkably, omics features of the hippocampus with NMN show that NMN leads to transcriptional changes of genes and proteins involved in MSR characteristics, principally within the astrocyte unit rather than microglia and oligodendrocytes. In brief, our work provides evidence that MSR has an active role in the pathogenesis of AD, as reducing mitochondrial homeostasis via atf4 depletion in AD mice aggravates the hallmarks of the disease; conversely, bolstering mitochondrial proteostasis by NMN decreases protein aggregation, restores memory performance, and delays disease progression, ultimately translating to increased healthspan.

Exploring the Mechanisms and Therapeutic Approaches of Mitochondrial Dysfunction in Alzheimer's Disease: An Educational Literature Review

Alzheimer's disease (AD) presents a significant challenge to global health. It is characterized by progressive cognitive deterioration and increased rates of morbidity and mortality among older adults. Among the various pathophysiologies of AD, mitochondrial dysfunction, encompassing conditions such as increased reactive oxygen production, dysregulated calcium homeostasis, and impaired mitochondrial dynamics, plays a pivotal role. This review comprehensively investigates the mechanisms of mitochondrial dysfunction in AD, focusing on aspects such as glucose metabolism impairment, mitochondrial bioenergetics, calcium signaling, protein tau and amyloid-beta-associated synapse dysfunction, mitophagy, aging, inflammation, mitochondrial DNA, mitochondria-localized microRNAs, genetics, hormones, and the electron transport chain and Krebs cycle. While lecanemab is the only FDA-approved medication to treat AD, we explore various therapeutic modalities for mitigating mitochondrial dysfunction in AD, including antioxidant drugs, antidiabetic agents, acetylcholinesterase inhibitors (FDA-approved to manage symptoms), nutritional supplements, natural products, phenylpropanoids, vaccines, exercise, and other potential treatments.

MicroRNAs: pioneering regulators in Alzheimer's disease pathogenesis, diagnosis, and therapy

This article delves into Alzheimer's disease (AD), a prevalent neurodegenerative condition primarily affecting the elderly. It is characterized by progressive memory and cognitive impairments, severely disrupting daily life. Recent research highlights the potential involvement of microRNAs in the pathogenesis of AD. MicroRNAs (MiRNAs), short non-coding RNAs comprising 20-24 nucleotides, significantly influence gene regulation by hindering translation or promoting degradation of target genes. This review explores the role of specific miRNAs in AD progression, focusing on their impact on β-amyloid (Aβ) peptide accumulation, intracellular aggregation of hyperphosphorylated tau proteins, mitochondrial dysfunction, neuroinflammation, oxidative stress, and the expression of the APOE4 gene. Our insights contribute to understanding AD's pathology, offering new avenues for identifying diagnostic markers and developing novel therapeutic targets.

Alleviating neuronal inflammation induced by Aβ42 in SH-SY5Y through interaction with polysialic acid-oligomannuronate conjugate

Amyloid beta (Aβ) aggregation is one of the distinctive pathological hallmarks of Alzheimer's disease (AD). Therefore, the development of effective inhibitors against Aβ aggregate formation offers great promise for the treatment of AD. In this study, we designed a novel negatively charged functionalized conjugate aimed at inhibiting Aβ42 aggregation and attenuating neurotoxicity by grafting polysialic acid with mannuronate oligosaccharide, a biocompatible glycan extracted from seaweeds, designated as polysialic acid-mannan conjugate (PSA-MOS). ThT, biological microscopy, TEM and CD confirmed the inhibition of Aβ42 aggregation by PSA-MOS, as well as its ability to inhibit the conformational transition of Aβ42 to β-sheet. CCK-8 assay demonstrated that PSA-MOS was not cytotoxic to SH-SY5Y (p < 0.05) and promoted cell proliferation. In the Aβ42-induced SH-SY5Y injury models, PSA-MOS dose-dependently ameliorated cytotoxicity (p < 0.0001) and significantly reduced the levels of inflammatory factors of IL-1β (p < 0.0001), IL-6 (p < 0.0001) and TNF-α (p < 0.05). MD simulations demonstrated that PSA-MOS effectively impeded the α-helix to β-sheet transition of the Aβ42 monomer via electrostatic interactions with its CTR and NTR regions. These findings demonstrate the therapeutic potential of PSA-MOS as promising glycoconjugate for the treatment of AD.

High fat diet affects the hippocampal expression of miRNAs targeting brain plasticity-related genes

Metabolic disorders such as insulin resistance and type 2 diabetes are associated with brain dysfunction and cognitive deficits, although the underpinning molecular mechanisms remain elusive. Epigenetic factors, such as non-coding RNAs, have been reported to mediate the molecular effects of nutrient-related signals. Here, we investigated the changes of miRNA expression profile in the hippocampus of a well-established experimental model of metabolic disease induced by high fat diet (HFD). In comparison to the control group fed with standard diet, we observed 69 miRNAs exhibiting increased expression and 63 showing decreased expression in the HFD mice's hippocampus. Through bioinformatics analysis, we identified numerous potential targets of the dysregulated miRNAs, pinpointing a subset of genes regulating neuroplasticity that were targeted by multiple differentially modulated miRNAs. We also validated the expression of these synaptic and non-synaptic proteins, confirming the downregulation of Synaptotagmin 1 (SYT1), calcium/calmodulin dependent protein kinase I delta (CaMK1D), 2B subunit of N-methyl-D-aspartate glutamate receptor (GRIN2B), the DNA-binding protein Special AT-Rich Sequence-Binding Protein 2 (SATB2), and RNA-binding proteins Cytoplasmic polyadenylation element-binding protein 1 (CPEB1) and Neuro-oncological ventral antigen 1 (NOVA1) in the hippocampus of HFD mice. In summary, our study offers a snapshot of the HFD-related miRNA landscape potentially involved in the alterations of brain functions associated with metabolic disorders. By shedding light on the specific miRNA-mRNA interactions, our research contributes to a deeper understanding of the molecular mechanisms underlying the effects of HFD on the synaptic function.

Recent advances in Alzheimer's disease: Mechanisms, clinical trials and new drug development strategies

Alzheimer's disease (AD) stands as the predominant form of dementia, presenting significant and escalating global challenges. Its etiology is intricate and diverse, stemming from a combination of factors such as aging, genetics, and environment. Our current understanding of AD pathologies involves various hypotheses, such as the cholinergic, amyloid, tau protein, inflammatory, oxidative stress, metal ion, glutamate excitotoxicity, microbiota-gut-brain axis, and abnormal autophagy. Nonetheless, unraveling the interplay among these pathological aspects and pinpointing the primary initiators of AD require further elucidation and validation. In the past decades, most clinical drugs have been discontinued due to limited effectiveness or adverse effects. Presently, available drugs primarily offer symptomatic relief and often accompanied by undesirable side effects. However, recent approvals of aducanumab (1) and lecanemab (2) by the Food and Drug Administration (FDA) present the potential in disrease-modifying effects. Nevertheless, the long-term efficacy and safety of these drugs need further validation. Consequently, the quest for safer and more effective AD drugs persists as a formidable and pressing task. This review discusses the current understanding of AD pathogenesis, advances in diagnostic biomarkers, the latest updates of clinical trials, and emerging technologies for AD drug development. We highlight recent progress in the discovery of selective inhibitors, dual-target inhibitors, allosteric modulators, covalent inhibitors, proteolysis-targeting chimeras (PROTACs), and protein-protein interaction (PPI) modulators. Our goal is to provide insights into the prospective development and clinical application of novel AD drugs.

Presenilin2 D439A Mutation Induces Dysfunction of Mitochondrial Fusion/Fission Dynamics and Abnormal Regulation of GTPase Activity

Alzheimer's disease (AD) is an age-related progressive neurodegenerative disease, and approximately 10% of AD cases are early-onset familial AD (EOFAD), which is mainly linked to point mutations in genes encoding presenilins (PS1 and PS2). Mutations in PS2 are extremely rare and have not received enough attention. Recently, studies have found that Rho GTPase activity is closely related to the pathogenesis of AD. In this study, we used transcriptome sequencing in PS2 siRNA-transfected SH-SY5Y cells and found a group of differentially expressed genes (DEGs) related to the regulation of GTPase activity. Among those DEGs, the most significantly downregulated was Rho guanine nucleotide exchange factor 5 (ARHGEF5). GTPase activity in PS2 siRNA-transfected cells was significantly decreased. Then, we found that the expression of ARHGEF5 and the GTPase activity of Mitochondrial Rho GTPase 2 (Miro2) in PS2 D439A mutant SH-SY5Y cells were significantly decreased. We found for the first time that PS2 can bind to Miro2, and the PS2 D439A mutation reduced the binding between PS2 and Miro2, reduced the expression of Miro2, and resulted in an imbalance in mitochondrial fusion/fission dynamics. In conclusion, PS2 gene knockdown may participate in the pathogenesis of AD through the regulation of GTPase activity. The imbalance in mitochondrial dynamics mediated by the PS2 D439A mutation through regulation of the expression and GTPase activity of Miro2 may be a potential pathogenic mechanism of AD.

Honokiol relieves hippocampal neuronal damage in Alzheimer's disease by activating the SIRT3-mediated mitochondrial autophagy

BACKGROUND

This work elucidated the effect of honokiol (HKL) on hippocampal neuronal mitochondrial function in Alzheimer's disease (AD).

METHODS

APP/PS1 mice were used as AD mice models and exposed to HKL and 3-TYP. Morris water maze experiment was performed to appraise cognitive performance of mice. Hippocampal Aβ+ plaque deposition and neuronal survival was evaluated by immunohistochemistry and Nissl staining. Hippocampal neurons were dissociated from C57BL/6 mouse embryos. Hippocampal neuronal AD model was constructed by Aβ oligomers induction and treated with HKL, CsA and 3-TYP. Neuronal viability and apoptosis were detected by cell counting kit-8 assay and TUNEL staining. mRFP-eGFP-LC3 assay, MitoSOX Red, dichlorodihydrofluorescein diacetate, and JC-1 staining were performed to monitor neuronal autophagosomes, mitochondrial reactive oxygen species (ROS), neuronal ROS, and mitochondrial membrane potential. Autophagy-related proteins were detected by Western blot.

RESULTS

In AD mice, HKL improved cognitive function, relieved hippocampal Aβ1-42 plaque deposition, promoted hippocampal neuron survival, and activated hippocampal SIRT3 expression and mitochondrial autophagy. These effects of HKL on AD mice were abolished by 3-TYP treatment. In hippocampal neuronal AD model, HKL increased neuronal activity, attenuated neuronal apoptosis and Aβ aggregation, activated SIRT3 and mitochondrial autophagy, reduced mitochondrial and neuronal ROS, and elevated mitochondrial membrane potential. CsA treatment and 3-TYP treatment abrogated the protection of HKL on hippocampal neuronal AD model. The promotion of mitochondrial autophagy by HKL in hippocampal neuronal AD model was counteracted by 3-TYP.

CONCLUSIONS

HKL activates SIRT3-mediated mitochondrial autophagy to mitigate hippocampal neuronal damage in AD. HKL may be effective in treating AD.

Revolutionizing early Alzheimer's disease and mild cognitive impairment diagnosis: a deep learning MRI meta-analysis

BACKGROUND

 The early diagnosis of Alzheimer's disease (AD) and mild cognitive impairment (MCI) remains a significant challenge in neurology, with conventional methods often limited by subjectivity and variability in interpretation. Integrating deep learning with artificial intelligence (AI) in magnetic resonance imaging (MRI) analysis emerges as a transformative approach, offering the potential for unbiased, highly accurate diagnostic insights.

OBJECTIVE

 A meta-analysis was designed to analyze the diagnostic accuracy of deep learning of MRI images on AD and MCI models.

METHODS

 A meta-analysis was performed across PubMed, Embase, and Cochrane library databases following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, focusing on the diagnostic accuracy of deep learning. Subsequently, methodological quality was assessed using the QUADAS-2 checklist. Diagnostic measures, including sensitivity, specificity, likelihood ratios, diagnostic odds ratio, and area under the receiver operating characteristic curve (AUROC) were analyzed, alongside subgroup analyses for T1-weighted and non-T1-weighted MRI.

RESULTS

 A total of 18 eligible studies were identified. The Spearman correlation coefficient was -0.6506. Meta-analysis showed that the combined sensitivity and specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio were 0.84, 0.86, 6.0, 0.19, and 32, respectively. The AUROC was 0.92. The quiescent point of hierarchical summary of receiver operating characteristic (HSROC) was 3.463. Notably, the images of 12 studies were acquired by T1-weighted MRI alone, and those of the other 6 were gathered by non-T1-weighted MRI alone.

CONCLUSION

 Overall, deep learning of MRI for the diagnosis of AD and MCI showed good sensitivity and specificity and contributed to improving diagnostic accuracy.

Role of senataxin in R-loop-mediated neurodegeneration

Senataxin is an RNA:DNA helicase that plays an important role in the resolution of RNA:DNA hybrids (R-loops) formed during transcription. R-loops are involved in the regulation of biological processes such as immunoglobulin class switching, gene expression and DNA repair. Excessive accumulation of R-loops results in DNA damage and loss of genomic integrity. Senataxin is critical for maintaining optimal levels of R-loops to prevent DNA damage and acts as a genome guardian. Within the nucleus, senataxin interacts with various RNA processing factors and DNA damage response and repair proteins. Senataxin interactors include survival motor neuron and zinc finger protein 1, with whom it co-localizes in sub-nuclear bodies. Despite its ubiquitous expression, mutations in senataxin specifically affect neurons and result in distinct neurodegenerative diseases such as amyotrophic lateral sclerosis type 4 and ataxia with oculomotor apraxia type 2, which are attributed to the gain-of-function and the loss-of-function mutations in senataxin, respectively. In addition, low levels of senataxin (loss-of-function) in spinal muscular atrophy result in the accumulation of R-loops causing DNA damage and motor neuron degeneration. Senataxin may play multiple functions in diverse cellular processes; however, its emerging role in R-loop resolution and maintenance of genomic integrity is gaining attention in the field of neurodegenerative diseases. In this review, we highlight the role of senataxin in R-loop resolution and its potential as a therapeutic target to treat neurodegenerative diseases.

Activation of GPER1 by G1 prevents PTSD-like behaviors in mice: Illustrating the mechanisms from BDNF/TrkB to mitochondria and synaptic connection

BACKGROUND

G1 is a specific agonist of G protein-coupled estrogen receptor 1 (GPER1), which binds and activates GPER1 to exert various neurological functions. However, the preventive effect of G1 on post-traumatic stress disorder (PTSD) and its mechanisms are unclear.

OBJECTIVE

To evaluate the protective effect of G1 against synaptic and mitochondrial impairments and to investigate the mechanism of G1 to improve PTSD from brain-derived neurotrophic factor (BDNF)/tyrosine kinase receptor B (TrkB) signaling.

METHODS

This study initially detected GPER1 expression in the hippocampus of single prolonged stress (SPS) mice, utilizing both Western blot and immunofluorescence staining. Subsequently, the effects of G1 on PTSD-like behaviors, synaptic, and mitochondrial functions in SPS mice were investigated. Additionally, the involvement of BDNF/TrkB signaling involved in the protection was further confirmed using GPER1 antagonist and TrkB inhibitor, respectively.

RESULTS

The expression of GPER1 was reduced in the hippocampus of SPS mice, and G1 treatment given for 14 consecutive days significantly improved PTSD-like behaviors in SPS mice compared with model group. Electrophysiological local field potential (LFP) results showed that G1 administration for 14 consecutive days could reverse the abnormal changes in the gamma oscillation in the CA1 region of SPS mice. Meanwhile, G1 administration for 14 consecutive days could significantly improve the abnormal expression of synaptic proteins, increase the expression of mitochondria-related proteins, increase the number of synapses in the hippocampus, and ameliorate the damage of hippocampal mitochondrial structure in SPS mice. In addition, G15 (GPER1 inhibitor) and ANA-12 (TrkB inhibitor) blocked the ameliorative effects of G1 on PTSD-like behaviors and aberrant expression of hippocampal synaptic and mitochondrial proteins in SPS mice and inhibited the reparative effects of G1 on structural damage to hippocampal mitochondria, respectively.

CONCLUSION

G1 improved PTSD-like behaviors in SPS mice, possibly by increasing hippocampal GPER1 expression and promoting BDNF/TrkB signaling to repair synaptic and mitochondrial functional impairments. This study would provide critical mechanism for the prevention and treatment of PTSD.

Causal relationships between peripheral immune cells and Alzheimer's disease: a two-sample Mendelian randomization study

OBJECTIVE

Previous research suggests that peripheral immune cells may play a role in the development of Alzheimer's disease (AD). Our study aims to determine if the composition of peripheral immune cells directly contributes to the occurrence of AD.

METHODS

We utilized a two-sample Mendelian randomization (MR) approach to examine the association between peripheral immune cells and AD.The primary analysis method used was the inverse variance weighted (IVW) method, and we also conducted analyses using MR Egger, weighted median, simple mode, and weighted mode methods to ensure the accuracy of the results.Heterogeneity and horizontal pleiotropy were evaluated using Cochran's Q statistics and the MR Egger intercept, respectively.

RESULTS

The study found a significant correlation between increased IgD + CD24- AC cells (Odds Ratio [OR] = 1.03, 95% Confidence Interval [CI] = 1.01-1.06, P = 0.0172), increased CD4 + %leukocyte (OR = 1.08, 95% CI = 1.02-1.14, P = 0.0086), and increased CD4 + CD8dim AC cells (OR = 1.06, 95% CI = 1.01-1.11, P = 0.0218), with an increased susceptibility to AD. Conversely, an increase in EM DN (CD4-CD8-) %T cells (OR = 0.95, 95% CI = 0.92-0.99, P = 0.0164) and an increase in DN (CD4-CD8-) AC cells (OR = 0.93, 95% CI = 0.88-0.99, P = 0.0145) were associated with a protective effect against AD.

CONCLUSION

Our findings establish a causal link between peripheral immune cells and AD. This study is the first to examine the relationship between peripheral immune cells and AD using MR, offering valuable insights for early diagnosis and treatment decisions.

Infectious viruses and neurodegenerative diseases: The mitochondrial defect hypothesis

Global attention is riveted on neurodegenerative diseases due to their unresolved aetiologies and lack of efficacious therapies. Two key factors implicated include mitochondrial impairment and microglial ageing. Several viral infections, including Herpes simplex virus-1 (HSV-1), human immunodeficiency virus (HIV) and Epstein-Barr virus, are linked to heightened risk of these disorders. Surprisingly, numerous studies indicate viruses induce these aforementioned precipitating events. Epstein-Barr virus, Hepatitis C Virus, HIV, respiratory syncytial virus, HSV-1, Japanese Encephalitis Virus, Zika virus and Enterovirus 71 specifically impact mitochondrial function, leading to mitochondrial malfunction. These vital organelles govern various cell activities and, under specific circumstances, trigger microglial ageing. This article explores the role of viral infections in elucidating the pathogenesis of neurodegenerative ailments. Various viruses instigate microglial ageing via mitochondrial destruction, causing senescent microglia to exhibit activated behaviour, thereby inducing neuroinflammation and contributing to neurodegeneration.

Neuroprotective effects of Shenghui decoction via inhibition of the JNK/p38 MAPK signaling pathway in an AlCl3-induced zebrafish (Danio rerio) model of Alzheimer's disease

ETHNOPHARMACOLOGICAL RELEVANCE

Alzheimer's disease (AD) is a multi-factorial degenerative disease, and multi-targeted therapies targeting multiple pathogenic mechanisms should be explored. Shenghui decoction (SHD) is an ancient traditional Chinese medicine (TCM) formula used clinically to alleviate AD. However, the precise mechanism of action of SHD as a therapeutic agent for AD remains unclear.

AIM OF THE STUDY

This study investigated the neuroprotective properties and potential mechanisms of action of SHD in mitigating AD-like symptoms induced by AlCl3 in a zebrafish model.

MATERIALS AND METHODS

Active components of SHD were detected using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Zebrafish were exposed to AlCl3 (200 μg/L) for 30 days to establish an AD zebrafish model. AlCl3-exposed zebrafish were treated with SHD or donepezil. Behavioral tests were used to assess learning and memory, locomotor activity, and AD-related anxiety and aggression in AlCl3-exposed zebrafish. Nissl staining and transmission electron microscopy were used to evaluate histological alterations in brain neurons. The concentrations of pro-inflammatory cytokines (tumor necrosis factor-α, TNF-α; interleukin-1β, IL-1β) were quantified using Enzyme-linked immunosorbent assay (ELISA). Markers of oxidative stress and cholinergic activity (acetylcholinesterase, AChE) were detected using biochemical assays. Western blotting and immunofluorescence were used to detect the protein expression levels of Aβ, p-tau, PSD-95, synaptophysin, TLR4, phosphorylation of NF-κB p65, p38, and JNK.

RESULTS

Fifteen SHD compounds were identified by UPLC-MS/MS analysis. SHD improved AlCl3-induced dyskinesia, learning and memory impairment, anxiety-like behavior, and aggressive behavior in zebrafish. AlCl3-exposed zebrafish showed AD-like pathology, overexpression of Aβ, hyperphosphorylated tau protein, marked neuronal damage, decreased expression of synaptic proteins, synaptophysin, and PSD-95, and impairment of synaptic structural plasticity. These effects were reversed by the SHD treatment. We also observed that SHD ameliorated oxidative stress and decreased AChE activity and inflammatory cytokine levels. These effects are similar to those observed for donepezil. Meanwhile, SHD could decrease the protein expression of TLR4 and inhibit phosphorylation of NF-κB, JNK, and p38 MAPK. These results demonstrate that SHD has the potential to exert neuroprotective effects, which may be partly mediated via inhibition of the JNK/p38 MAPK signaling pathway.

CONCLUSIONS

Our findings revealed the therapeutic mechanism of SHD in mitigating AD progression and suggested that SHD is a potent neuroprotectant that contributes to the future development of TCM modernization and broader clinical applications.

Molecular crosstalk and putative mechanisms underlying mitochondrial quality control: The hidden link with methylmercury-induced cognitive impairment

Methylmercury (MeHg) is a neurotoxin associated with foetal neurodevelopmental and adult cognitive deficits. Neurons are highly dependent on the tricarboxylic acid cycle and oxidative phosphorylation to produce ATP and meet their high energy demands. Therefore, mitochondrial quality control (MQC) is critical for neuronal homeostasis. While existing studies have generated a wealth of data on the toxicity of MeHg, the complex cascades and molecular pathways governing the mitochondrial network remain to be elucidated. Here, 0.6, 1.2 and 2.4 mg/kg body weight of MeHg were administered intragastrically to pregnant Sprague Dawley rats to model maternal MeHg exposure. The results of the in vivo study revealed that MeHg-treated rats tended to perform more directionless repetitive strategies in the Morris Water Maze and fewer target-orientation strategies than control offspring. Moreover, pathological injury and synaptic toxicity were observed in the hippocampus. Transmission electron microscopy (TEM) demonstrated that the autophagosomes encapsulated damaged mitochondria, while showing a typical mitochondrial fission phenotype, which was supported by the activation of PINK1-dependent key regulators of mitophagy. Moreover, there was upregulation of DRP1 and FIS1. Additionally, MeHg compensation promoted mitochondrial biogenesis, as evidenced by the activation of the mitochondrial PGC1-α-NRF1-TFAM signalling pathway. Notably, SIRT3/AMPK was activated by MeHg, and the expression and activity of p-AMPK, p-LKB1 and SIRT3 were consistently coordinated. Collectively, these findings provide new insights into the potential molecular mechanisms regulating MeHg-induced cognitive deficits through SIRT3/AMPK MQC network coordination.

Regulatory roles of microRNAs in modulating mitochondrial dynamics, amyloid beta fibrillation, microglial activation, and cholinergic signaling: Implications for alzheimer's disease pathogenesis

Alzheimer's Disease (AD) remains a formidable challenge due to its complex pathology, notably involving mitochondrial dysfunction and dysregulated microRNA (miRNA) signaling. This study delves into the underexplored realm of miRNAs' impact on mitochondrial dynamics and their interplay with amyloid-beta (Aβ) aggregation and tau pathology in AD. Addressing identified gaps, our research utilizes advanced molecular techniques and AD models, alongside patient miRNA profiles, to uncover miRNAs pivotal in mitochondrial regulation. We illuminate novel miRNAs influencing mitochondrial dynamics, Aβ, and tau, offering insights into their mechanistic roles in AD progression. Our findings not only enhance understanding of AD's molecular underpinnings but also spotlight miRNAs as promising therapeutic targets. By elucidating miRNAs' roles in mitochondrial dysfunction and their interactions with hallmark AD pathologies, our work proposes innovative strategies for AD therapy, aiming to mitigate disease progression through targeted miRNA modulation. This contribution marks a significant step toward novel AD treatments, emphasizing the potential of miRNAs in addressing this complex disease.

Mitochondria-Associated MicroRNAs and Parkinson's Disease

Parkinson's Disease (PD) occurs as a result of the progressive loss of dopaminergic neurons within the substantia nigra causing motor and non-motor symptoms and has become more prevalent within the last several decades. With mitochondria being essential to cellular survival, mitochondrial dysfunction contributes to the disease progression by increasing neuron loss through (1) insufficient ATP production and (2) reactive oxygen species generation. MicroRNAs (miRNAs) are small molecules located throughout cells that regulate gene expression, particularly mitochondrial function. Through their own dysregulation, miRNAs offset the delicate balance of mitochondrial function by altering or dysregulating the expression of proteins, increasing neuroinflammation, increasing retention of toxic substances, limiting the removal of reactive oxygen species, and preventing mitophagy. Improper mitochondrial function places cells at increased risk of apoptosis, a major concern in individuals with PD due to their reduced number of dopaminergic neurons. This article has identified the 17 most promising mitochondrial associated miRNAs within PD: hsa-miR-4639-5p, miR-376a, miR-205, miR-421, miR-34b/c, miR-150, miR-7, miR-132, miR-17-5p, miR-20a, miR-93, miR-106, miR-181, miR-193b, miR-128, miR-181a, and miR-124-3p. These miRNAs alter mitochondrial function and synaptic energy by impeding normal gene expression when up or downregulated. However, there is limited research regarding mitochondria-localized miRNAs that are typically seen in other diseases. Mitochondria-localized miRNA may have a greater impact on mitochondrial dysfunction due to their proximity. Further research is needed to determine the location of these miRNAs and to better understand their regulatory capabilities on mitochondrial and synaptic function within PD.

Human dental pulp stem cells mitigate the neuropathology and cognitive decline via AKT-GSK3β-Nrf2 pathways in Alzheimer's disease

Oxidative stress is increasingly recognized as a major contributor to the pathophysiology of Alzheimer's disease (AD), particularly in the early stages of the disease. The multiplicity advantages of stem cell transplantation make it fascinating therapeutic strategy for many neurodegenerative diseases. We herein demonstrated that human dental pulp stem cells (hDPSCs) mediated oxidative stress improvement and neuroreparative effects in in vitro AD models, playing critical roles in regulating the polarization of hyperreactive microglia cells and the recovery of damaged neurons. Importantly, these therapeutic effects were reflected in 10-month-old 3xTg-AD mice after a single transplantation of hDPSCs, with the treated mice showing significant improvement in cognitive function and neuropathological features. Mechanistically, antioxidant and neuroprotective effects, as well as cognitive enhancements elicited by hDPSCs, were at least partially mediated by Nrf2 nuclear accumulation and downstream antioxidant enzymes expression through the activation of the AKT-GSK3β-Nrf2 signaling pathway. In conclusion, our findings corroborated the neuroprotective capacity of hDPSCs to reshape the neuropathological microenvironment in both in vitro and in vivo AD models, which may be a tremendous potential therapeutic candidate for Alzheimer's disease.

Mitophagy activation by rapamycin enhances mitochondrial function and cognition in 5×FAD mice

Alzheimer's disease (AD) is the most prevalent form of dementia, characterized by severe mitochondrial dysfunction, which is an intracellular process that is significantly compromised in the early stages of AD. Mitophagy, the selective removal of damaged mitochondria, is a potential therapeutic strategy for AD. Rapamycin, a mammalian target of rapamycin (mTOR) inhibitor, augmented autophagy and mitigated cognitive impairment. Our study revealed that rapamycin enhances cognitive function by activating mitophagy, alleviating neuronal loss, and improving mitochondrial dysfunction in 5 ×FAD mice. Interestingly, the neuroprotective effect of rapamycin in AD were negated by treatment with 3-MA, a mitophagy inhibitor. Overall, our findings suggest that rapamycin ameliorates cognitive impairment in 5 ×FAD mice via mitophagy activation and its downstream PINK1-Parkin pathway, which aids in the clearance of amyloid-β (Aβ) and damaged mitochondria. This study reveals a novel mechanism involving mitophagy regulation underlying the therapeutic effect of rapamycin in AD. This study provides new insights and therapeutic targets for rapamycin in the treatment of AD. However, there are still some shortcomings in this topic; if we can further knock out the PINK1/Parkin gene in animals or use siRNA technology, we can further confirm the experimental results.

Biomarker profiling to determine clinical impact of microRNAs in cognitive disorders

Alzheimer's disease (AD) and post-stroke cognitive impairment (PSCI) are the leading causes of progressive dementia related to neurodegenerative and cerebrovascular injuries in elderly populations. Despite decades of research, patients with these conditions still lack minimally invasive, low-cost, and effective diagnostic and treatment methods. MicroRNAs (miRNAs) play a vital role in AD and PSCI pathology. As they are easily obtained from patients, miRNAs are promising candidates for the diagnosis and treatment of these two disorders. In this study, we performed complete sequencing analysis of miRNAs from 24 participants, split evenly into the PSCI, post-stroke non-cognitive impairment (PSNCI), AD, and normal control (NC) groups. To screen for differentially expressed miRNAs (DE-miRNAs) in patients, we predicted their target genes using bioinformatics analysis. Our analyses identified miRNAs that can distinguish between the investigated disorders; several of them were novel and never previously reported. Their target genes play key roles in multiple signaling pathways that have potential to be modified as a clinical treatment. In conclusion, our study demonstrates the potential of miRNAs and their key target genes in disease management. Further in-depth investigations with larger sample sizes will contribute to the development of precise treatments for AD and PSCI.

ABCA7 deficiency causes neuronal dysregulation by altering mitochondrial lipid metabolism

ABCA7 loss-of-function variants are associated with increased risk of Alzheimer's disease (AD). Using ABCA7 knockout human iPSC models generated with CRISPR/Cas9, we investigated the impacts of ABCA7 deficiency on neuronal metabolism and function. Lipidomics revealed that mitochondria-related phospholipids, such as phosphatidylglycerol and cardiolipin were reduced in the ABCA7-deficient iPSC-derived cortical organoids. Consistently, ABCA7 deficiency-induced alterations of mitochondrial morphology accompanied by reduced ATP synthase activity and exacerbated oxidative damage in the organoids. Furthermore, ABCA7-deficient iPSC-derived neurons showed compromised mitochondrial respiration and excess ROS generation, as well as enlarged mitochondrial morphology compared to the isogenic controls. ABCA7 deficiency also decreased spontaneous synaptic firing and network formation in iPSC-derived neurons, in which the effects were rescued by supplementation with phosphatidylglycerol or NAD+ precursor, nicotinamide mononucleotide. Importantly, effects of ABCA7 deficiency on mitochondria morphology and synapses were recapitulated in synaptosomes isolated from the brain of neuron-specific Abca7 knockout mice. Together, our results provide evidence that ABCA7 loss-of-function contributes to AD risk by modulating mitochondria lipid metabolism.

A review of the mechanisms of abnormal ceramide metabolism in type 2 diabetes mellitus, Alzheimer's disease, and their co-morbidities

The global prevalence of type 2 diabetes mellitus (T2DM) and Alzheimer's disease (AD) is rapidly increasing, revealing a strong association between these two diseases. Currently, there are no curative medication available for the comorbidity of T2DM and AD. Ceramides are structural components of cell membrane lipids and act as signal molecules regulating cell homeostasis. Their synthesis and degradation play crucial roles in maintaining metabolic balance in vivo, serving as important mediators in the development of neurodegenerative and metabolic disorders. Abnormal ceramide metabolism disrupts intracellular signaling, induces oxidative stress, activates inflammatory factors, and impacts glucose and lipid homeostasis in metabolism-related tissues like the liver, skeletal muscle, and adipose tissue, driving the occurrence and progression of T2DM. The connection between changes in ceramide levels in the brain, amyloid β accumulation, and tau hyper-phosphorylation is evident. Additionally, ceramide regulates cell survival and apoptosis through related signaling pathways, actively participating in the occurrence and progression of AD. Regulatory enzymes, their metabolites, and signaling pathways impact core pathological molecular mechanisms shared by T2DM and AD, such as insulin resistance and inflammatory response. Consequently, regulating ceramide metabolism may become a potential therapeutic target and intervention for the comorbidity of T2DM and AD. The paper comprehensively summarizes and discusses the role of ceramide and its metabolites in the pathogenesis of T2DM and AD, as well as the latest progress in the treatment of T2DM with AD.

The role of RLIP76 in oxidative stress and mitochondrial dysfunction: Evidence based on autopsy brains from Alzheimer's disease patients

Several converging lines of evidence from our group support a potential role of RLIP76 (AKA Rlip) in neurodegenerative disorders, including Alzheimer's Disease (AD). However, the role of Rlip in Alzheimer's and other neurodegenerative diseases is not well understood. The purpose of the present study is to determine the role of Rlip in the brains of AD patients and control subjects. To achieve our goals, we used frozen tissues and formalin-fixed paraffin-embedded postmortem brains from AD patients of different Braak stages and age-matched control subjects. Our immunohistology and immunoblotting blotting analysis revealed that expression of Rlip protein gradually and significantly decreased (p = 0.0001) with AD progression, being lowest in Braak stage IV-V. Rlip was colocalized with Amyloid beta (Aβ) and phosphorylated tau (p-Tau) as observed by IHC staining and co-immunoprecipitation studies. Lipid peroxidation (4-HNE generation) and H2O2 production were significantly higher (p = 0.004 and 0.0001 respectively) in AD patients compared to controls, and this was accompanied by lower ATP production in AD (p = 0.0009). Oxidative DNA damage was measured by 8-Hydroxyguanosine (8-OHdG) in tissue lysates by ELISA and COMET assay. AD 8-OHdG levels were significantly higher (p = 0.0001) compared to controls. COMET assay was performed in brain cells, isolated from frozen postmortem samples. The control samples showed minimal DNA in comets representing few DNA strand breaks (<20 %), (score-0-1). However, the AD group showed an average of 50 % to 65 % of DNA in comet tails (score-4-5) indicating numerous DNA strand breaks. The difference between the two groups was significant (p = 0.001), as analyzed by Open Comet by ImageJ. Elevated DNA damage was further examined by western blot analysis for phosphorylated histone variant H2AX (γH2AX). Induction of γH2AX was very significant (p < 0.0001) and confirmed the presence of double-strand breaks in DNA. Overall, our results indicate an important role for Rlip in maintaining neuronal health and homeostasis by suppressing cellular oxidative stress and DNA damage. Based on our findings, we cautiously conclude that Rlip is a promising therapeutic target for Alzheimer's disease.

Investigating the Potential Shared Molecular Mechanisms between COVID-19 and Alzheimer's Disease via Transcriptomic Analysis

SARS-CoV-2 caused the COVID-19 pandemic. COVID-19 may elevate the risk of cognitive impairment and even cause dementia in infected individuals; it may accelerate cognitive decline in elderly patients with dementia, possibly in Alzheimer's disease (AD) patients. However, the mechanisms underlying the interplay between AD and COVID-19 are still unclear. To investigate the underlying mechanisms and associations between AD progression and SARS-CoV-2 infection, we conducted a series of bioinformatics research into SARS-CoV-2-infected cells, COVID-19 patients, AD patients, and SARS-CoV-2-infected AD patients. We identified the common differentially expressed genes (DEGs) in COVID-19 patients, AD patients, and SARS-CoV-2-infected cells, and these DEGs are enriched in certain pathways, such as immune responses and cytokine storms. We constructed the gene interaction network with the signaling transduction module in the center and identified IRF7, STAT1, STAT2, and OAS1 as the hub genes. We also checked the correlations between several key transcription factors and the SARS-CoV-2 and COVID-19 pathway-related genes. We observed that ACE2 expression is positively correlated with IRF7 expression in AD and coronavirus infections, and interestingly, IRF7 is significantly upregulated in response to different RNA virus infections. Further snRNA-seq analysis indicates that NRGN neurons or endothelial cells may be responsible for the increase in ACE2 and IRF7 expression after SARS-CoV-2 infection. The positive correlation between ACE2 and IRF7 expressions is confirmed in the hippocampal formation (HF) of SARS-CoV-2-infected AD patients. Our findings could contribute to the investigation of the molecular mechanisms underlying the interplay between AD and COVID-19 and to the development of effective therapeutic strategies for AD patients with COVID-19.

Abnormal interaction of Rlip with mutant APP/Abeta and phosphorylated tau reduces wild-type Rlip levels and disrupt Rlip function in Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disease that affects a large proportion of the aging population. RalBP1 (Rlip) is a stress-activated protein, that plays an important role in aging and neurodegenerative diseases such as Alzheimer's disease. Mutant APP and mutant Tau interact with the Rlip protein which leads to decreased wild-type Rlip levels and disrupt Rlip function in Alzheimer's disease. Rlip is a promising new target for aging, Alzheimer's disease, and other neurological diseases.

Drug Target to Alleviate Mitochondrial Dysfunctions in Alzheimer's Disease: Recent Advances and Therapeutic Implications

Alzheimer's disease (AD) is a severe progressive neurodegenerative condition associated with neuronal damage and reduced cognitive function that primarily affects the aged worldwide. While there is increasing evidence suggesting that mitochondrial dysfunction is one of the most significant factors contributing to AD, its accurate pathobiology remains unclear. Mitochondrial bioenergetics and homeostasis are impaired and defected during AD pathogenesis. However, the potential of mutations in nuclear or mitochondrial DNA encoding mitochondrial constituents to cause mitochondrial dysfunction has been considered since it is one of the intracellular processes commonly compromised in early AD stages. Additionally, electron transport chain dysfunction and mitochondrial pathological protein interactions are related to mitochondrial dysfunction in AD. Many mitochondrial parameters decline during aging, causing an imbalance in reactive oxygen species (ROS) production, leading to oxidative stress in age-related AD. Moreover, neuroinflammation is another potential causative factor in AD-associated mitochondrial dysfunction. While several treatments targeting mitochondrial dysfunction have undergone preclinical studies, few have been successful in clinical trials. Therefore, this review discusses the molecular mechanisms and different therapeutic approaches for correcting mitochondrial dysfunction in AD, which have the potential to advance the future development of novel drug-based AD interventions.

Cognitive impairment is associated with BDNF-TrkB signaling mediating synaptic damage and reduction of amino acid neurotransmitters in heart failure

Heart failure (HF) is often accompanied by cognitive impairment (CI). Brain-derived neurotrophic factor (BDNF) deficiency is closely associated with CI. However, the role and mechanism of BDNF in HF with CI is still not fully understood. Here, the case-control study was designed including 25 HF without CI patients (HF-NCI) and 50 HF with CI patients (HF-CI) to investigate the predictive value of BDNF in HF-CI while animal and cell experiments were used for mechanism research. Results found that BDNF levels in serum neuronal-derived exosomes were downregulated in HF-CI patients. There was no significant difference in serum BDNF levels among the two groups. HF rats showed obvious impairment in learning and memory; also, they had reduced thickness and length of postsynaptic density (PSD) and increased synaptic cleft width. Expression of BDNF, TrkB, PSD95, and VGLUT1 was significantly decreased in HF rats brain. In addition, compared with sham rats, amino acids were significantly reduced with no changes in the acetylcholine and monoamine neurotransmitters. Further examination showed that the number of synaptic bifurcations and the expression of BDNF, TrkB, PSD95, and VGLUT1 were all decreased in the neurons that interfered with BDNF-siRNA compared with those in the negative control neurons. Together, our results demonstrated that neuronal-derived exosomal BDNF act as effective biomarkers for prediction of HF-CI. The decrease of BDNF in the brain triggers synaptic structural damage and a decline in amino acid neurotransmitters via the BDNF-TrkB-PSD95/VGLUT1 pathway. This discovery unveils a novel pathological mechanism underlying cognitive impairment following heart failure.

Oxidative damage in neurodegeneration: roles in the pathogenesis and progression of Alzheimer disease

Alzheimer disease (AD) is associated with multiple etiologies and pathological mechanisms, among which oxidative stress (OS) appears as a major determinant. Intriguingly, OS arises in various pathways regulating brain functions, and it seems to link different hypotheses and mechanisms of AD neuropathology with high fidelity. The brain is particularly vulnerable to oxidative damage, mainly because of its unique lipid composition, resulting in an amplified cascade of redox reactions that target several cellular components/functions ultimately leading to neurodegeneration. The present review highlights the "OS hypothesis of AD," including amyloid beta-peptide-associated mechanisms, the role of lipid and protein oxidation unraveled by redox proteomics, and the antioxidant strategies that have been investigated to modulate the progression of AD. Collected studies from our groups and others have contributed to unraveling the close relationships between perturbation of redox homeostasis in the brain and AD neuropathology by elucidating redox-regulated events potentially involved in both the pathogenesis and progression of AD. However, the complexity of AD pathological mechanisms requires an in-depth understanding of several major intracellular pathways affecting redox homeostasis and relevant for brain functions. This understanding is crucial to developing pharmacological strategies targeting OS-mediated toxicity that may potentially contribute to slow AD progression as well as improve the quality of life of persons with this severe dementing disorder.

Insights into role of microRNA in Alzheimer's disease: From contemporary research to bedside perspective

One of the most prevalent neurodegenerative disorders is Alzheimer's disease (AD). Despite the pervasiveness of AD being considerable, the rates of both diagnosis and therapy are comparatively less and still lacking. For the treatment of AD, acetylcholinesterase inhibitors and NMDA receptor antagonists (Memantine) have received clinical approval. The approved drugs are only capable of mitigating the symptoms; however, halting the progression of the disease remains a matter of substantial concern. MicroRNAs (miRs) are a subclass of non-coding single-stranded RNA molecules that target mRNAs to control the expression of genes in certain tissues. Dysregulation in the expression and function of miRs contributes to a neurodegeneration-like pathogenesis seen in Alzheimer's disease (AD), featuring hallmark characteristics such as Aβ aggregation, hyper-phosphorylation of Tau proteins, mitochondrial dysfunction, neuroinflammation, and apoptosis. These factors collectively underpin the cognitive deterioration and learning disabilities associated with AD. According to the research, numerous miRs have considerably different expression patterns in AD patients compared to healthy people. Due to these attributes, miRs prove to be effective diagnostic and therapeutic agents for AD. This review will examine clinical and preclinical data concerning the potential of miRs as diagnostic and therapeutic agents, utilizing various techniques (such as miR antagonists or inhibitors, miR agonists or mimics, miR sponges, and miR antisense oligonucleotides) to target specific pathogenic mechanisms in AD.

miRNA-137-5p improves spatial memory and cognition in Alzheimer's mice by targeting ubiquitin-specific peptidase 30

BACKGROUND

Alzheimer's disease (AD) is a prevalent neurodegenerative disorder causing progressive dementia. Research suggests that microRNAs (miRNAs) could serve as biomarkers and therapeutic targets for AD. Reduced levels of miR-137 have been observed in the brains of AD patients, but its specific role and downstream mechanisms remain unclear. This study sought to examine the therapeutic potential of miR-137-5p agomir in alleviating cognitive dysfunction induced in AD models and explore its potential mechanisms.

METHODS

This study utilized bioinformatic analysis and a dual-luciferase reporter assay to investigate the relationship between miR-137-5p and ubiquitin-specific peptidase 30 (USP30). In vitro experiments were conducted using SH-SY5Y cells to assess the impact of miR-137-5p on Aβ1-42 neurotoxicity. In vivo experiments on AD mice evaluated the effects of miR-137-5p on cognition, Aβ1-42 deposition, Tau hyperphosphorylation, and neuronal apoptosis, as well as its influence on USP30 levels.

RESULTS

It was discovered that miR-137-5p mimics efficiently counteract Aβ1-42 neurotoxicity in SH-SY5Y cells, a protective effect that is negated by USP30 overexpression. In vivo experiments demonstrated that miR-137-5p enhances the cognition and mobility of AD mice, significantly reducing Aβ1-42 deposition, Tau hyperphosphorylation, and neuronal apoptosis within the hippocampus and cortex regions. Mechanistically, miR-137-5p significantly suppresses USP30 levels in mice, though USP30 overexpression partially buffers against miR-137-5p-induced AD symptom improvement.

CONCLUSION

Our study proposes that miR-137-5p, by instigating the downregulation of USP30, has the potential to act as a novel and promising therapeutic target for AD.

The role of mitochondrial dynamics in disease

Mitochondria are multifaceted and dynamic organelles regulating various important cellular processes from signal transduction to determining cell fate. As dynamic properties of mitochondria, fusion and fission accompanied with mitophagy, undergo constant changes in number and morphology to sustain mitochondrial homeostasis in response to cell context changes. Thus, the dysregulation of mitochondrial dynamics and mitophagy is unsurprisingly related with various diseases, but the unclear underlying mechanism hinders their clinical application. In this review, we summarize the recent developments in the molecular mechanism of mitochondrial dynamics and mitophagy, particularly the different roles of key components in mitochondrial dynamics in different context. We also summarize the roles of mitochondrial dynamics and target treatment in diseases related to the cardiovascular system, nervous system, respiratory system, and tumor cell metabolism demanding high-energy. In these diseases, it is common that excessive mitochondrial fission is dominant and accompanied by impaired fusion and mitophagy. But there have been many conflicting findings about them recently, which are specifically highlighted in this view. We look forward that these findings will help broaden our understanding of the roles of the mitochondrial dynamics in diseases and will be beneficial to the discovery of novel selective therapeutic targets.

Factors affecting the GABAergic synapse function in Alzheimer's disease: Focus on microRNAs

Alzheimer's disease (AD) is a progressive neurological disease characterized by the loss of cognitive function, confusion, and memory deficit. Accumulation of abnormal proteins, amyloid beta (Aß), and phosphorylated Tau (p-tau) forms plaques and tangles that deteriorate synapse function, resulting in neurodegeneration and cognitive decline in AD. The human brain is composed of different types of neurons and/or synapses that are functionally defective in AD. The GABAergic synapse, the most abundant inhibitory neuron in the human brain was found to be dysfunctional in AD and contributes to disrupting neurological function. This study explored the types of GABA receptors associated with neurological dysfunction and various biological and environmental factors that cause GABAergic neuron dysfunction in AD, such as Aβ, p-tau, aging, sex, astrocytes, microglia, APOE, mental disorder, diet, physical activity, and sleep. Furthermore, we explored the role of microRNAs (miRNAs) in the regulation of GABAergic synapse function in neurological disorders and AD states. We also discuss the molecular mechanisms underlying GABAergic synapse dysfunction with a focus on miR-27b, miR-30a, miR-190a/b, miR-33, miR-51, miR-129-5p, miR-376-3p, miR-376c, miR-30b and miR-502-3p. The purpose of our article is to highlight the recent research on miRNAs affecting the regulation of GABAergic synapse function and factors that contribute to the progression of AD.

Healthy brain aging and delayed dementia in Texas rural elderly

Healthy aging is the process of preserving and enhancing one's independence, physical and mental well-being, and overall quality of life. It involves the mental, emotional, and cognitive wellness. Although biological and genetic factors have a significant influence on the process of aging gracefully, other adjustable factors also play a crucial role. Adopting positive behaviors such as maintaining a nutritious and balanced diet, engaging in regular physical activity, effectively managing stress and anxiety, ensuring sufficient sleep, nurturing spiritual coping mechanisms, and prioritizing overall well-being from an early stage can collectively influence both lifespan and the quality of health during advanced years. We aim to explore the potential impacts of biological, psychosocial, and environmental factors on the process of healthy cognitive aging in individuals who exhibit healthy aging. Additionally, we plan to present initial findings that demonstrate how maintaining good cognitive health during aging could potentially postpone the emergence of neurodegenerative disorders. We hypothesize that there will be strong associations between biological, environmental, and social factors that cause some elderly to be superior in cognitive health than others. For preliminary data collection, we recruited 25 cognitively healthy individuals and 5 individuals with MCI/AD between the ages of 60-90 years. We conducted anthropometric measurements, and blood biomarker testing, administered surveys, and obtained structural brain magnetic resonance imaging (MRI) scans. The Montreal Cognitive Assessment (MoCA) scores and sub-scores for the healthy group were also reported. We found that at baseline, individuals exhibiting healthy cognitive aging, and those with MCI/AD had comparable measures of anthropometrics and blood biomarkers. The healthy group exhibited lower signs of brain volume loss and the ones observed were age-related. Moreover, within the healthy group, there was a significant correlation (p = 0.003) between age and MoCA scores. Conversely, within the individuals with MCI/AD, the MRI scans showed disease signs of grey and white matter and loss of cerebral volume. Healthy brain aging is a scientific area that remains under-explored. Our current study findings support our hypothesis. Future studies are required in diverse populations to determine the various biological, psychological, environmental, lifestyle, and social factors that contribute to it.

Role of diet and exercise in aging, Alzheimer's disease, and other chronic diseases

Alzheimer's disease (AD) is a progressive neurodegenerative disease, characterized by memory loss and multiple cognitive impairments. Genetic mutations cause a small proportion (1-2%) of early-onset AD, with mutations in amyloid precursor protein (APP), presenilin 1 (PS1) and presenilin 2 (PS2). Major contributing factors of late-onset AD are ApoE4 genotype, traumatic brain injury, diabetes, obesity, hypertension, cardiovascular conditions, in addition to lifestyle factors, such as unhealthy diet and lack of physical exercise. Disease progression can be delayed and/or prevented to a greater extent by adopting healthy lifestyle with balanced and antioxidant enriched diet and daily exercise. The interaction and interplay of diet, exercise, age, and pharmacological interventions holds a crucial role in the progression, pathogenesis and management of AD and its comorbidities, including diabetes, obesity, hypertension and cardiovascular conditions. Antioxidant enriched diet contributes to brain health, glucose control, weight management, and cardiovascular well-being. Regular exercise removes toxins including free radicals and enhances insulin sensitivity, and supports cardiovascular function. In the current article, we discussed, the role of diet, and exercise in aging, AD and other conditions including diabetes, obesity, hypertension, cardiovascular conditions. This article also highlights the impact of medication, socioeconomic and lifestyle factors, and pharmacological interventions. These aspects were discussed in different races and ethnic groups in Texas, and the US.

Sex-specific declines in cholinergic-targeting tRNA fragments in the nucleus accumbens in Alzheimer's disease

INTRODUCTION

Females with Alzheimer's disease (AD) suffer accelerated dementia and loss of cholinergic neurons compared to males, but the underlying mechanisms are unknown. Seeking causal contributors to both these phenomena, we pursued changes in transfer RNS (tRNA) fragments (tRFs) targeting cholinergic transcripts (CholinotRFs).

METHODS

We analyzed small RNA-sequencing (RNA-Seq) data from the nucleus accumbens (NAc) brain region which is enriched in cholinergic neurons, compared to hypothalamic or cortical tissues from AD brains; and explored small RNA expression in neuronal cell lines undergoing cholinergic differentiation.

RESULTS

NAc CholinotRFs of mitochondrial genome origin showed reduced levels that correlated with elevations in their predicted cholinergic-associated mRNA targets. Single-cell RNA seq from AD temporal cortices showed altered sex-specific levels of cholinergic transcripts in diverse cell types; inversely, human-originated neuroblastoma cells under cholinergic differentiation presented sex-specific CholinotRF elevations.

DISCUSSION

Our findings support CholinotRFs contributions to cholinergic regulation, predicting their involvement in AD sex-specific cholinergic loss and dementia.

Co-administration of dl-3-n-butylphthalide and neprilysin is neuroprotective in Alzheimer disease associated with mild traumatic brain injury

dl-3-n-Butylphthalide is a potent synthetic Chinese celery extract that is highly efficient in inducing neuroprotection in concussive head injury (CHI), Parkinson's disease, Alzheimer's disease, stroke as well as depression, dementia, anxiety and other neurological diseases. Thus, there are reasons to believe that dl-3-n-butylphthalide could effectively prevent Alzheimer's disease brain pathology. Military personnel during combat operation or veterans are often the victims of brain injury that is a major risk factor for developing Alzheimer's disease in their later lives. In our laboratory we have shown that CHI exacerbates Alzheimer's disease brain pathology and reduces the amyloid beta peptide (AβP) inactivating enzyme neprilysin. We have used TiO2 nanowired-dl-3-n-butylphthalide in attenuating Parkinson's disease brain pathology exacerbated by CHI. Nanodelivery of dl-3-n-butylphthalide appears to be more potent as compared to the conventional delivery of the compound. Thus, it would be interesting to examine the effects of nanowired dl-3-n-butylphthalide together with nanowired delivery of neprilysin in Alzheimer's disease model on brain pathology. In this investigation we found that nanowired delivery of dl-3-n-butylphthalide together with nanowired neprilysin significantly attenuated brain pathology in Alzheimer's disease model with CHI, not reported earlier. The possible mechanism and clinical significance is discussed based on the current literature.

Stress induced exacerbation of Alzheimer's disease brain pathology is thwarted by co-administration of nanowired cerebrolysin and monoclonal amyloid beta peptide antibodies with serotonin 5-HT6 receptor antagonist SB-399885

Alzheimer's disease is one of the devastating neurodegenerative diseases affecting mankind worldwide with advancing age mainly above 65 years and above causing great misery of life. About more than 7 millions are affected with Alzheimer's disease in America in 2023 resulting in huge burden on health care system and care givers and support for the family. However, no suitable therapeutic measures are available at the moment to enhance quality of life to these patients. Development of Alzheimer's disease may reflect the stress burden of whole life inculcating the disease processes of these neurodegenerative disorders of the central nervous system. Thus, new strategies using nanodelivery of suitable drug therapy including antibodies are needed in exploring neuroprotection in Alzheimer's disease brain pathology. In this chapter role of stress in exacerbating Alzheimer's disease brain pathology is explored and treatment strategies are examined using nanotechnology based on our own investigation. Our observations clearly show that restraint stress significantly exacerbate Alzheimer's disease brain pathology and nanodelivery of a multimodal drug cerebrolysin together with monoclonal antibodies (mAb) to amyloid beta peptide (AβP) together with a serotonin 5-HT6 receptor antagonist SB399885 significantly thwarted Alzheimer's disease brain pathology exacerbated by restraint stress, not reported earlier. The possible mechanisms and future clinical significance is discussed.

Mitochondria and Brain Disease: A Comprehensive Review of Pathological Mechanisms and Therapeutic Opportunities

Mitochondria play a vital role in maintaining cellular energy homeostasis, regulating apoptosis, and controlling redox signaling. Dysfunction of mitochondria has been implicated in the pathogenesis of various brain diseases, including neurodegenerative disorders, stroke, and psychiatric illnesses. This review paper provides a comprehensive overview of the intricate relationship between mitochondria and brain disease, focusing on the underlying pathological mechanisms and exploring potential therapeutic opportunities. The review covers key topics such as mitochondrial DNA mutations, impaired oxidative phosphorylation, mitochondrial dynamics, calcium dysregulation, and reactive oxygen species generation in the context of brain disease. Additionally, it discusses emerging strategies targeting mitochondrial dysfunction, including mitochondrial protective agents, metabolic modulators, and gene therapy approaches. By critically analysing the existing literature and recent advancements, this review aims to enhance our understanding of the multifaceted role of mitochondria in brain disease and shed light on novel therapeutic interventions.

Neuroimaging in Dementia: More than Typical Alzheimer Disease

Alzheimer disease (AD) is the most common cause of dementia. The prevailing theory of the underlying pathology assumes amyloid accumulation followed by tau protein aggregation and neurodegeneration. However, the current antiamyloid and antitau treatments show only variable clinical efficacy. Three relevant points are important for the radiologic assessment of dementia. First, besides various dementing disorders (including AD, frontotemporal dementia, and dementia with Lewy bodies), clinical variants and imaging subtypes of AD include both typical and atypical AD. Second, atypical AD has overlapping radiologic and clinical findings with other disorders. Third, the diagnostic process should consider mixed pathologies in neurodegeneration, especially concurrent cerebrovascular disease, which is frequent in older age. Neuronal loss is often present at, or even before, the onset of cognitive decline. Thus, for effective emerging treatments, early diagnosis before the onset of clinical symptoms is essential to slow down or stop subsequent neuronal loss, requiring molecular imaging or plasma biomarkers. Neuroimaging, particularly MRI, provides multiple imaging parameters for neurodegenerative and cerebrovascular disease. With emerging treatments for AD, it is increasingly important to recognize AD variants and other disorders that mimic AD. Describing the individual composition of neurodegenerative and cerebrovascular disease markers while considering overlapping and mixed diseases is necessary to better understand AD and develop efficient individualized therapies.

The Role of microRNAs in Epigenetic Regulation of Signaling Pathways in Neurological Pathologies

In recent times, there has been a significant increase in researchers' interest in the functions of microRNAs and the role of these molecules in the pathogenesis of many multifactorial diseases. This is related to the diagnostic and prognostic potential of microRNA expression levels as well as the prospects of using it in personalized targeted therapy. This review of the literature analyzes existing scientific data on the involvement of microRNAs in the molecular and cellular mechanisms underlying the development of pathologies such as Alzheimer's disease, cerebral ischemia and reperfusion injury, and dysfunction of the blood-brain barrier.