siRNA Mediated GSK3β Knockdown Targets Insulin Signaling Pathway and Rescues Alzheimer's Disease Pathology: Evidence from In Vitro and In Vivo Studies

Cellulose-like chitosan microfibrils facilitate targeted release and enhance the prolonged residence time of quercetin-selenium nanoparticles for Alzheimer's disease treatment

The effect of digestion on nanocarriers will affect the release and pharmacological effects of bioactive compounds in delivery systems. The digestion of cellulose is limited to gut microbiota, which offers a new research strategy for targeted delivery of bioactive compounds. Herein, positively charged cellulose-like chitosan/polyvinylpyrrolidone nanofiber was prepared to improve the residence time, colon target and gut microbiota regulation activity of quercetin decorated selenium nanoparticles (QUE@SeNPs/CS/PVPNFs). Selenium nanoparticles block the degradation of quercetin and QUE@SeNPs/CS/PVPNFs only decompose when caused by chitosanase secretion from gut microbiota. In vivo imaging showed that the residence time of QUE@SeNPs/CS/PVPNFs was longer than that of QUE@SeNPs. Thus, it significantly decreased the lipid concentrations in liver, which further inhibited insulin resistance in mice. Moreover, QUE@SeNPs/CS/PVPNFs treatment improves gut barrier integrity, increased the relative abundance of anti-obesity and anti-inflammation related bacterial including Akkermansia, Lactobacillus and Bacteroides. Consequently, the inflammatory factor (IL-β and TNF-α) levels in gut, liver and brain were also decreased. Nissl and PSD-95 staining indicated that QUE@SeNPs/CS/PVPNFs ameliorated synapse dysfunction in the brain. Therefore, QUE@SeNPs/CS/PVPNFs has a greater effect than QUE@SeNPs in improving cognitive ability in Morris water maze. Overall, QUE@SeNPs/CS/PVPNFs with prolonged residence time attenuates cognitive disorder via gut-liver-brain axis in AD.

Nanoscale drug formulations for the treatment of Alzheimer's disease progression

Alzheimer's disease (AD) is a devastating neurodegenerative disorder with no effective disease-modifying treatments. The blood-brain barrier hinders drug delivery to the brain, limiting therapeutic efficacy. Nanoparticle-based systems have emerged as promising tools to overcome these challenges. This review highlights recent advances in nanoparticle technologies for AD treatment, including liposomes, polymeric, inorganic, and biomimetic nanoparticles. These nanoparticles improve drug delivery across the blood-brain barrier, improve stability and bioavailability, and enable targeted delivery to affected brain regions. Functionalization strategies further enhance their therapeutic potential. Multifunctional nanoparticles combining therapeutic and diagnostic properties offer theranostic approaches. While progress has been made, challenges related to safety, targeting precision, and clinical translation remain. Future perspectives emphasize the need for collaborative efforts to optimize nanoparticle design, conduct rigorous studies, and accelerate the development of effective nanotherapeutics. With continued innovation, nanoparticle-based delivery systems hold great promise for revolutionizing AD treatment.

Molecular Signaling Pathways of Quercetin in Alzheimer's Disease: A Promising Arena

Alzheimer's disease (AD) is a neurodegenerative disease characterized by cognitive impairment and memory deficit. Even with extensive research and studies, presently, there is no effective treatment for the management of AD. Besides, most of drugs used in the treatment of AD did not avert the AD neuropathology, and the disease still in a progressive status. For example, acetyl cholinesterase inhibitors are associated with many adverse effects, such as insomnia and nightmares. As well, acetylcholinesterase inhibitors augment cholinergic neurotransmission leading to the development of adverse effects related to high acetylcholine level, such as salivation, rhinorrhea, vomiting, loss of appetite, and seizure. Furthermore, tacrine has poor bioavailability and causes hepatotoxicity. These commonly used drugs do not manage the original causes of AD. For those reasons, natural products were repurposed for the treatment of AD and neurodegenerative diseases. It has been shown that phytochemicals produce neuroprotective effects against the development and progression of neurodegenerative diseases by different mechanisms, including antioxidant and anti-inflammatory effects. Quercetin (QCN) has been reported to exert an effective neuroprotective effect against AD and other neurodegenerative diseases by lessening oxidative stress. In this review, electronic databases such as PubMed, Scopus, and Web of Science were searched for possible relevant studies and article linking the effect of QCN on AD. Findings from this review highlighted that many studies highlighted different mechanistic signaling pathways regarding the neuroprotective effect of QCN in AD. Nevertheless, the precise molecular mechanism of QCN in AD was not completely clarified. Consequently, this review aims to discuss the molecular mechanism of QCN in AD.

Should We Consider Neurodegeneration by Itself or in a Triangulation with Neuroinflammation and Demyelination? The Example of Multiple Sclerosis and Beyond

Neurodegeneration is preeminent in many neurological diseases, and still a major burden we fail to manage in patient's care. Its pathogenesis is complicated, intricate, and far from being completely understood. Taking multiple sclerosis as an example, we propose that neurodegeneration is neither a cause nor a consequence by itself. Mitochondrial dysfunction, leading to energy deficiency and ion imbalance, plays a key role in neurodegeneration, and is partly caused by the oxidative stress generated by microglia and astrocytes. Nodal and paranodal disruption, with or without myelin alteration, is further involved. Myelin loss exposes the axons directly to the inflammatory and oxidative environment. Moreover, oligodendrocytes provide a singular metabolic and trophic support to axons, but do not emerge unscathed from the pathological events, by primary myelin defects and cell apoptosis or secondary to neuroinflammation or axonal damage. Hereby, trophic failure might be an overlooked contributor to neurodegeneration. Thus, a complex interplay between neuroinflammation, demyelination, and neurodegeneration, wherein each is primarily and secondarily involved, might offer a more comprehensive understanding of the pathogenesis and help establishing novel therapeutic strategies for many neurological diseases and beyond.

Zebrafish as a model organism to study sporadic Alzheimer's disease: Behavioural, biochemical and histological validation

Alzheimer's disease (AD) is a global burden to the healthcare system with no viable treatment options till date. Rodents and primates have been extensively used as models for understanding AD pathogenesis and identifying therapeutic targets. However, the focus is now shifting towards developing alternate models. Zebrafish is emerging as a preferred model for neurodegenerative conditions because of its simple nervous system, highly conserved genome and short duration required to model disease condition. The present study is aimed to develop streptozotocin (STZ)-induced model of sporadic AD (sAD) in zebrafish. STZ was administered to adult zebrafish (4-6 mo) at different doses (1 to 50 mg/kg body weight, intracerebroventricularly). Kaplan-Meier survival analysis revealed time and dose dependent mortality in the zebrafish administered with STZ. Based on survival analysis, 1 to 10 mg/kg body weight of STZ was selected for behavioural, molecular and histological studies. STZ administered fish had anxiety and stress-like behaviour in novel tank and light/dark preference tests. STZ-induced cognitive and memory deficits assessed using novel object recognition and spatial alternation tests. Further, expression of markers of amyloidogenic pathway (appa and bace1) were increased in terms of mRNA and protein levels in a time and dose dependent manner following STZ administration. However, expression of non-amyloidogenic pathway mediator (adam10) was reduced at both mRNA and protein level. Histological assessment using hematoxylin and eosin, and Nissl stain revealed loss of neurons in STZ administered fish. The ratio of phosphor-tauser396/total-tau was increased in STZ administered fish. Based on these findings, 5 mg/kg body weight of STZ was found to be most appropriate dose to exhibit sAD phenotype. Mass spectrometric analysis confirmed the presence of amyloid beta oligomers in brains of STZ administered fish. Transmission electron microscopy also showed the presence of higher order insoluble amyloid fibrils with twists. Immunohistochemical analysis revealed amyloid beta deposits in brain of STZ administered fish. Golgi-cox staining indicated decreased number of dendrites, whereas microglia had increased density, span ratio, soma area and lacunarity. The results of the present study demonstrate presence of AD hallmarks and phenotype in zebrafish 7 days post STZ administration (5 mg/kg). The study validates the potential of STZ-induced sAD in zebrafish as a reliable model for studying pathophysiology and rapid screening of therapeutic molecules against sAD.

Emerging paradigms in Alzheimer's therapy

Alzheimer's disease is a neurodegenerative disorder that affects elderly, and its incidence is continuously increasing across the globe. Unfortunately, despite decades of research, a complete cure for Alzheimer's disease continues to elude us. The current medications are mainly symptomatic and slow the disease progression but do not result in reversal of all disease pathologies. The growing body of knowledge on the factors responsible for the onset and progression of the disease has resulted in the identification of new targets that could be targeted for treatment of Alzheimer's disease. This has opened new vistas for treatment of Alzheimer's disease that have moved away from chemotherapeutic agents modulating a single target to biologics and combinations that acted on multiple targets thereby offering better therapeutic outcomes. This review discusses the emerging directions in therapeutic interventions against Alzheimer's disease highlighting their merits that promise to change the treatment paradigm and challenges that limit their clinical translation.

Advances in carrier-delivered small interfering RNA based therapeutics for treatment of neurodegenerative diseases

Neurodegenerative diseases are devastating diseases that severely affect the health of people all over the world. RNA therapies have become one of the most promising critical drug treatments for neurodegenerative diseases due to their excellent gene and protein editing effects. However, the successful transport of RNA via the systemic route to the central nervous system remains one of the major obstacles in treating neurodegenerative diseases. This review will focus on therapeutic RNA that can successfully overcome the blood-brain barrier (BBB), with particular attention to small interfering RNAs (siRNAs), focusing on different types of neurodegenerative disease treatment strategies and accelerating their translation into clinical practice.

Identification of immune infiltration and PANoptosis-related molecular clusters and predictive model in Alzheimer's disease based on transcriptome analysis

This study aims to explore the expression profile of PANoptosis-related genes (PRGs) and immune infiltration in Alzheimer's disease (AD). Based on the Gene Expression Omnibus database, this study investigated the differentially expressed PRGs and immune cell infiltration in AD and explored related molecular clusters. Gene set variation analysis (GSVA) was used to analyze the expression of Gene Ontology and Kyoto Encyclopedia of Genes and Genomes in different clusters. Weighted gene co-expression network analysis was utilized to find co-expressed gene modules and core genes in the network. By analyzing the intersection genes in random forest, support vector machine, generalized linear model, and extreme gradient boosting (XGB), the XGB model was determined. Eventually, the first five genes (Signal Transducer and Activator of Transcription 3, Tumor Necrosis Factor (TNF) Receptor Superfamily Member 1B, Interleukin 4 Receptor, Chloride Intracellular Channel 1, TNF Receptor Superfamily Member 10B) in XGB model were selected as predictive genes. This research explored the relationship between PANoptosis and AD and established an XGB learning model to evaluate and screen key genes. At the same time, immune infiltration analysis showed that there were different immune infiltration expression profiles in AD.

Alterations of mRNAs and Non-coding RNAs Associated with Neuroinflammation in Alzheimer's Disease

Alzheimer's disease is a neurodegenerative pathology whose pathognomonic hallmarks are increased generation of β-amyloid (Aβ) peptide, production of hyperphosphorylated (pTau), and neuroinflammation. The last is an alteration closely related to the progression of AD and although it is present in multiple neurodegenerative diseases, the pathophysiological events that characterize neuroinflammatory processes vary depending on the disease. In this article, we focus on mRNA and non-coding RNA alterations as part of the pathophysiological events characteristic of neuroinflammation in AD and the influence of these alterations on the course of the disease through interaction with multiple RNAs related to the generation of Aβ, pTau, and neuroinflammation itself.

GSK3: A potential target and pending issues for treatment of Alzheimer's disease

Glycogen synthase kinase-3 (GSK3), consisting of GSK3α and GSK3β subtypes, is a complex protein kinase that regulates numerous substrates. Research has observed increased GSK3 expression in the brains of Alzheimer's disease (AD) patients and models. AD is a neurodegenerative disorder with diverse pathogenesis and notable cognitive impairments, characterized by Aβ aggregation and excessive tau phosphorylation. This article provides an overview of GSK3's structure and regulation, extensively analyzing its relationship with AD factors. GSK3 overactivation disrupts neural growth, development, and function. It directly promotes tau phosphorylation, regulates amyloid precursor protein (APP) cleavage, leading to Aβ formation, and directly or indirectly triggers neuroinflammation and oxidative damage. We also summarize preclinical research highlighting the inhibition of GSK3 activity as a primary therapeutic approach for AD. Finally, pending issues like the lack of highly specific and affinity-driven GSK3 inhibitors, are raised and expected to be addressed in future research. In conclusion, GSK3 represents a target in AD treatment, filled with hope, challenges, opportunities, and obstacles.

Mind the Metabolic Gap: Bridging Migraine and Alzheimer's disease through Brain Insulin Resistance

Brain insulin resistance has recently been described as a metabolic abnormality of brain glucose homeostasis that has been proven to downregulate insulin receptors, both in astrocytes and neurons, triggering a reduction in glucose uptake and glycogen synthesis. This condition may generate a mismatch between brain's energy reserve and expenditure, ??mainly during high metabolic demand, which could be involved in the chronification of migraine and, in the long run, at least in certain subsets of patients, in the prodromic phase of Alzheimer's disease, along a putative metabolic physiopathological continuum. Indeed, the persistent disruption of glucose homeostasis and energy supply to neurons may eventually impair protein folding, an energy-requiring process, promoting pathological changes in Alzheimer's disease, such as amyloid-β deposition and tau hyperphosphorylation. Hopefully, the "neuroenergetic hypothesis" presented herein will provide further insight on there being a conceivable metabolic bridge between chronic migraine and Alzheimer's disease, elucidating novel potential targets for the prophylactic treatment of both diseases.

Functionalized nanoparticles to deliver nucleic acids to the brain for the treatment of Alzheimer's disease

Brain-targeted gene delivery across the blood-brain barrier (BBB) is a significant challenge in the 21st century for the healthcare sector, particularly in developing an effective treatment strategy against Alzheimer's disease (AD). The Internal architecture of the brain capillary endothelium restricts bio-actives entry into the brain. Additionally, therapy with nucleic acids faces challenges like vulnerability to degradation by nucleases and potential immune responses. Functionalized nanocarrier-based gene delivery approaches have resulted in safe and effective platforms. These nanoparticles (NPs) have demonstrated efficacy in protecting nucleic acids from degradation, enhancing transport across the BBB, increasing bioavailability, prolonging circulation time, and regulating gene expression of key proteins involved in AD pathology. We provided a detailed review of several nanocarriers and targeting ligands such as cell-penetrating peptides (CPPs), endogenous proteins, and antibodies. The utilization of functionalized NPs extends beyond a singular system, serving as a versatile platform for customization in related neurodegenerative diseases. Only a few numbers of bioactive regimens can go through the BBB. Thus, exploring functionalized NPs for brain-targeted gene delivery is of utmost necessity. Currently, genes are considered high therapeutic potential molecules for altering any disease-causing gene. Through surface modification, nanoparticulate systems can be tailored to address various diseases by replacing the target-specific molecule on their surface. This review article presents several nanoparticulate delivery systems, such as lipid NPs, polymeric micelles, exosomes, and polymeric NPs, for nucleic acids delivery to the brain and the functionalization strategies explored in AD research.

TFR1 knockdown alleviates iron overload and mitochondrial dysfunction during neural differentiation of Alzheimer's disease-derived induced pluripotent stem cells by interacting with GSK3B

Iron metabolism disorders are implicated in the pathogenesis of Alzheimer's disease (AD). It was previously reported that transferrin receptor (TFR1) expression was upregulated in AD mouse model. However, the precise biological functions of TFR1 in AD progression remains unclear. Herein, we observed a gradual increase in TFR1 protein expression during the differentiation of AD patient-derived induced pluripotent stem cells (AD-iPS). TFR1 knockdown inhibited the protein expression of ferritin and ferritin heavy chain 1 (FTH1), enhanced the expression of ferroportin 1 (FPN1), and decreased intracellular levels of total iron, labile iron, and reactive oxygen species (ROS). Moreover, TFR1 knockdown improved mitochondrial membrane potential (MMP), increased adenosine triphosphate (ATP) content, downregulated mitochondrial fission proteins, and upregulated mitochondrial fusion proteins. TFR1 knockdown alleviated iron overload and mitochondrial dysfunction in neural cells differentiated from AD-iPS, while TFR1 overexpression showed the opposite results. Additionally, TFR1interacted with glycogen synthase kinase 3 beta (GSK3B) and promoted GSK3B expression. GSK3B overexpression reversed the inhibitory effects of TFR1 knockdown on iron overload and mitochondrial dysfunction in AD-iPS differentiated neural cells. In conclusion, TFR1 knockdown alleviated iron overload and mitochondrial dysfunction in neural cells differentiated from AD-iPS by promoting GSK3B expression. Our findings provide a potential therapeutic target for the treatment of AD.

RNA therapeutics for neurological diseases

INTRODUCTION

Ribonucleic acid (RNA) therapeutics are a new class of drugs whose importance is highlighted by the growing number of molecules in the clinic.

SOURCES OF DATA

We focus on RNA therapeutics for neurogenetic disorders, which are broadly defined as diseases with a genetic background and with at least one clinical sign affecting the nervous system. A systematic search identified 14 RNA drugs approved by FDA and many others in development.

AREAS OF AGREEMENT

The field of RNA therapeutics is changing the therapeutic scenario across many disorders.

AREAS OF CONTROVERSY

Despite its recent successes, RNA therapeutics encountered several hurdles and some clinical failures. Delivery to the brain represents the biggest challenge.

GROWING POINTS

The many advantages of RNA drugs make the development of these technologies a worthwhile investment.

AREAS TIMELY FOR DEVELOPING RESEARCH

Clinical failures stress the importance of implementing clinical trial design and optimizing RNA molecules to hold the promise of revolutionizing the treatment of human diseases.

TREM2 deficiency inhibits microglial activation and aggravates demyelinating injury in neuromyelitis optica spectrum disorder

Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory demyelinating disorder of the central nervous system (CNS) triggered by autoimmune mechanisms. Microglia are activated and play a pivotal role in response to tissue injury. Triggering receptor expressed on myeloid cells 2 (TREM2) is expressed by microglia and promotes microglial activation, survival and phagocytosis. Here, we identify a critical role for TREM2 in microglial activation and function during AQP4-IgG and complement-induced demyelination. TREM2-deficient mice had more severe tissue damage and neurological impairment, as well as fewer oligodendrocytes with suppressed proliferation and maturation. The number of microglia clustering in NMOSD lesions and their proliferation were reduced in TREM2-deficient mice. Moreover, morphology analysis and expression of classic markers showed compromised activation of microglia in TREM2-deficient mice, which was accompanied by suppressed phagocytosis and degradation of myelin debris by microglia. These results overall indicate that TREM2 is a key regulator of microglial activation and exert neuroprotective effects in NMOSD demyelination.

A Flower-like Brain Targeted Selenium Nanocluster Lowers the Chlorogenic Acid Dose for Ameliorating Cognitive Impairment in APP/PS1 Mice

Aβ aggregation-related neuroinflammation and imbalance of brain glucose homeostasis play important roles in the pathological process of Alzheimer's disease (AD). Chlorogenic acid (CGA) is one of the most common dietary polyphenols with neuroprotective effects. However, due to the low bioavailability of CGA, its application dose is usually high in vivo. In our previous study, the spherical selenium nanoparticles act as drug carriers to improve the bioactivity of resveratrol. Here, the brain-targeting peptide (TGN peptide) and CGA were used to prepare a new flowerlike selenium nanocluster (TGN-CGA@SeNCs) for enhancing the bioavailability of CGA. After decoration on selenium nanoclusters, the solubility and stability of CGA was obviously increased. Oral administration of a low dose of CGA (80 mg/kg/body weight) only slightly inhibited Aβ aggregate-related neuroinflammation and glucose homeostasis disorder in the brain. Moreover, CGA showed less effect on increasing the diversity and richness of gut microbiota. At the same concentration, the CGA-modified selenium nanocluster (CGA@SeNCs) and TGN-CGA@SeNCs showed better function in ameliorating the gut microbiota disorder. Especially, TGN-CGA@SeNCs significantly increased the relative abundance of Turicibacter, Colidextribacter, Ruminococcus, Alloprevotella, and Alistipes against oxidative stress, inflammation, and glucose homeostasis imbalance. Notably, only TGN-CGA@SeNCs can transport through the blood-brain barrier (BBB), and TGN-CGA@SeNCs showed better effects than CGA@SeNCs in regulating Aβ aggregation and improving brain glucose homeostasis. These results broadened the application of TGN-CGA@SeNCs, effectively improving the bioactivity of CGA, which also lowers the CGA dose for preventing AD progression.

Systems Medicine as a Strategy to Deal with Alzheimer's Disease

The traits of Alzheimer's disease (AD) include amyloid plaques made of Aβ1-40 and Aβ1-42, and neurofibrillary tangles by the hyperphosphorylation of tau protein. AD is a complex disorder that is heterogenous in genetical, neuropathological, and clinical contexts. Current available therapeutics are unable to cure AD. Systems medicine is a strategy by viewing the body as a whole system, taking into account each individual's unique health profile, provide treatment and associated nursing care clinically for the patient, aiming for precision. Since the onset of AD can lead towards cognitive impairment, it is vital to intervene and diagnose early and prevent further progressive loss of neurons. Moreover, as the individual's brain functions are impaired due to neurodegeneration in AD, it is essential to reconstruct the neurons or brain cells to enable normal brain functions. Although there are different subtypes of AD due to varied pathological lesions, in the majority cases of AD, neurodegeneration and severe brain atrophy develop at the chronic stage. Novel approaches including RNA based gene therapy, stem cell based technology, bioprinting technology, synthetic biology for brain tissue reconstruction are researched in recent decades in the hope to decrease neuroinflammation and restore normal brain function in individuals of AD. Systems medicine include the prevention of disease, diagnosis and treatment by viewing the individual's body as a whole system, along with systems medicine based nursing as a strategy against AD that should be researched further.

Probiotic supplement as a promising strategy in early tau pathology prevention: Focusing on GSK-3β?

Neurofibrillary tangles (NFT) is one of the hallmarks of Alzheimer's disease (AD). Recent research suggests that pretangle tau, the soluble precursor of NFT, is an initiator for AD pathogenesis, thus targeting pretangle tau pathology may be a promising early intervention focus. The bidirectional communications between the gut and the brain play a crucial role in health. The compromised gut-brain axis is involved in various neurodegenerative diseases including AD. However, most research on the relationship between gut microbiome and AD have focused on amyloid-β. In this mini review, we propose to target preclinical pretangle tau stages with gut microbiota interventions such as probiotic supplementation. We discuss the importance of targeting pretangle tau that starts decades before the onset of clinical symptoms, and potential intervention focusing on probiotic regulation of tau hyperphosphorylation. A particular focus is on GSK-3β, a protein kinase that is at the interface between tau phosphorylation, AD and diabetes mellitus.

Combinational treatments of RNA interference and extracellular vesicles in the spinocerebellar ataxia

Spinocerebellar ataxia (SCA) is an autosomal dominant neurodegenerative disease (ND) with a high mortality rate. Symptomatic treatment is the only clinically adopted treatment. However, it has poor effect and serious complications. Traditional diagnostic methods [such as magnetic resonance imaging (MRI)] have drawbacks. Presently, the superiority of RNA interference (RNAi) and extracellular vesicles (EVs) in improving SCA has attracted extensive attention. Both can serve as the potential biomarkers for the diagnosing and monitoring disease progression. Herein, we analyzed the basis and prospect of therapies for SCA. Meanwhile, we elaborated the development and application of miRNAs, siRNAs, shRNAs, and EVs in the diagnosis and treatment of SCA. We propose the combination of RNAi and EVs to avoid the adverse factors of their respective treatment and maximize the benefits of treatment through the technology of EVs loaded with RNA. Obviously, the combinational therapy of RNAi and EVs may more accurately diagnose and cure SCA.