Involvement of trigeminal axons in nose-to-brain delivery of glucagon-like peptide-2 derivative

Nose-to-brain drug delivery: from bench to bedside

There is increasing interest in nose-to-brain delivery as an innovative drug delivery strategy for neurodegenerative disorders such as Parkinson's or Alzheimer's disease. The unique anatomy of the nose-brain interface facilitates direct drug transport via the olfactory and trigeminal pathways to the brain, bypassing the blood-brain barrier. Different administration techniques as well as advanced drug formulations like targeted nanoparticles and thermoresponsive systems have been explored to improve the delivery efficiency and the therapeutic efficacy. This review provides an up-to-date perspective on this fast-developing field, and discusses different studies on safety and pharmacokinetic properties. A thorough evaluation of preclinical and clinical studies reveals both promises and challenges of this delivery method, highlighting approved drugs for the treatment of epilepsy and migraine that successfully utilize intranasal routes. The current landscape of research on nose-to-brain delivery is critically discussed, and a rationale is provided for ongoing research to optimize therapeutic strategies.

The review of nasal drug delivery system: The strategies to enhance the efficiency of intranasal drug delivery by improving drug absorption

Nasal drug administration constitutes an efficient and non-invasive modality of drug delivery, and its distinctive physiological structure offers potentialities for treating a variety of diseases. To elevate the drug absorption and delivery efficiency, it is of paramount importance to delineate the transport routes and their enhancement mechanisms. Nevertheless, drug absorption pathways vary depending on the disease target, these variations present opportunities for targeted delivery and challenges for achieving precision. Hence, this review outlines the anatomical structure of the nasal cavity, and subsequently elaborates on the drug transport pathways within the nasal cavity and their influencing factors. Based on the distinct sites of drug action, diseases suitable for nasal drug administration are categorized into three types: systemic diseases, local nasal diseases, and central nervous system diseases. Grounded on multiple transport routes and their influencing factors, this review proposes strategies like optimizing formulation viscosity, using penetration enhancers, adding mucosal adhesives and improving delivery device, offering insights into future advancements in nasal drug delivery systems.

Glucagon-like peptide-1 receptor agonists in neurodegenerative diseases: Promises and challenges

Glucagon-like peptide-1 (GLP-1) receptor agonists (GRA) belong to a class of compounds that reduce blood glucose and energy intake by simulating actions of endogenous incretin hormone GLP-1 after it is released by the gut following food consumption. They are used to treat type 2 diabetes mellitus (T2DM) and obesity and have systemic effects on various organs, including the brain, liver, pancreas, heart, and the gut. Patients with T2DM have a higher risk of developing neurodegenerative diseases (NDs), including Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS) and Huntington's disease (HD), accompanied by more severe motor deficits and faster disease progression, suggesting dysregulation of insulin signaling in these diseases. Experimental studies have shown that GRA have protective effects to modulate neuroinflammation, oxidative stress, mitochondrial and autophagic functions, and protein misfolding. Hence the compounds have generated enormous interest as novel therapeutic agents against NDs. To date, clinical trials have shown that three GRA, exenatide, liraglutide and lixisenatide can improve motor deficits as an add-on therapy in PD patients and liraglutide can improve cognitive function in AD patients. The neuroprotective effects of these and other GRA, such as PT320 (a sustained-released exenatide) and semaglutide, are still under investigation. The dual GLP-1/gastric inhibitory polypeptide (GIP) receptor agonists have been demonstrated to have beneficial effects in AD and PD mice models. Overall, GRA are highly promising novel drugs, but future clinical studies should identify which subsets of patients should be targeted as potential candidates for their symptomatic and/or neuroprotective benefits, investigate whether combinations with other classes of drugs can further augment their efficacy, and evaluate their long-term disease-modifying and adverse effects.

Nose-to-Brain Delivery of Circular RNA SCMH1-Loaded Lipid Nanoparticles for Ischemic Stroke Therapy

Ischemic stroke represents one of the leading cerebrovascular diseases with a high rate of mortality and disability globally. To date, there are no effective clinical drugs available to improve long-term outcomes for post-stroke patients. A novel nucleic acid agent circSCMH1 which can promote sensorimotor function recovery in rodent and nonhuman primate animal stroke models has been found. However, there are still delivery challenges to overcome for its clinical implementation. Besides, its effects on post-stroke cognitive functions remain unexplored. Herein, lipid nanoparticle circSCMH1@LNP1 is established to deliver circSCMH1 and explore its therapeutic efficacy comprehensively. Distribution experiments demonstrate that intranasal administration of circSCMH1@LNP1 significantly increases circSCMH1 distribution in the peri-infarct region and reduces its non-specific accumulation in other organs compared to intravenous injection. Therapeutic results indicate that circSCMH1@LNP1 promotes synaptic plasticity, vascular repair, neuroinflammation relief, and myelin sheath formation, thereby achieving enhanced sensorimotor and cognitive function recovery in post-stroke mice. In conclusion, this research presents a simple and effective LNP system for efficient delivery of circSCMH1 via intranasal administration to repair post-stroke brain injury. It is envisioned that this study may bridge a crucial gap between basic research and translational application, paving the way for clinical implementation of novel circSCMH1 in post-stroke patient management.

Advances in cell-penetrating peptide-based nose-to-brain drug delivery systems

The incidence of brain disorders has gained worldwide attention and the presence of the blood-brain barrier prevents numerous drugs from reaching the targeted brain. The specific physiology of the nasal cavity and the brain provides the feasibility of direct nose-brain delivery, a system that bypasses the blood-brain barrier in a non-invasive manner for brain-targeted drug delivery via intracellular and extracellular mechanisms. The use of CPPs provides further feasibility for naso-brain drug delivery studies, and liposomes, nanopolymer particles, and gels modified with CPPs have demonstrated significant brain-targeting capabilities after nasal delivery. In this paper, the physiology of the nasal cavity and brain, the pathways of naso-brain delivery and the influencing factors are discussed in detail. At the same time, the introduction, classification, mechanism of action and application of CPPs in the nasal-brain delivery system are discussed in detail to provide a theoretical basis for the in-depth study of the application of CPPs in the nasal-brain delivery system.

Dodecyl creatine ester, a promising treatment to deliver creatine to neurons, achieves pharmacology efficacy in creatine transporter deficiency

Dodecyl creatine ester (DCE) is a creatine prodrug currently developed for brain diseases, including creatine transporter deficiency (CTD), an incurable rare genetic disease. A dual strategy combining a prodrug to bypass the non-functional creatine transporter and its delivery via the nose-to-brain pathway has been proposed to replenish creatine levels in cerebral cells, particularly in neurons of CTD patients. In vitro and in vivo studies in various animal models, including wild-type non-human primates and creatine transporter deficient mice, show that formulated DCE, when administered intranasally, achieves significant cerebral distribution up to the target cells, the neurons, and modulates the expression of neuronal markers related to cognitive function at doses intended for patients. These compelling results contribute to a better understanding of the pharmacokinetics and pharmacodynamics of DCE after nasal administration, with a particular focus on the crucial role of the nose-to-brain pathway in DCE distribution.

Current strategic arsenal and advances in nose to brain nanotheranostics for therapeutic intervention of glioblastoma multiforme

The fight against Glioblastoma multiforme (GBM) is ongoing and the long-term outlook for GBM remains challenging due to low prognosis but every breakthrough brings us closer to improving patient outcomes. Significant hurdles in GBM are heterogeneity, fortified tumor location, and blood-brain barrier (BBB), hindering adequate drug concentrations within functioning brain regions, thus leading to low survival rates. The nasal passageway has become an appealing location to commence the course of cancer therapy. Utilization of the nose-to-brain (N2B) route for drug delivery takes a sidestep from the BBB to allow therapeutics to directly access the central nervous system (CNS) and enhance drug localization in the vicinity of the tumor. This comprehensive review provides insights into pertinent anatomy and cellular organization of the nasal cavity, present-day diagnostic tools, intracranial invasive therapies, and advancements in intranasal (IN) therapies in GBM models for better clinical outcomes. Also, this review highlights groundbreaking carriers and delivery techniques that could revolutionize GBM management such as biomimetics, image guiding-drug delivery, and photodynamic and photothermal therapies for GBM management.

Targeting the hypothalamus for modeling age-related DNA methylation and developing OXT-GnRH combinational therapy against Alzheimer's disease-like pathologies in male mouse model

The hypothalamus plays an important role in aging, but it remains unclear regarding the underlying epigenetics and whether this hypothalamic basis can help address aging-related diseases. Here, by comparing mouse hypothalamus with two other limbic system components, we show that the hypothalamus is characterized by distinctively high-level DNA methylation during young age and by the distinct dynamics of DNA methylation and demethylation when approaching middle age. On the other hand, age-related DNA methylation in these limbic system components commonly and sensitively applies to genes in hypothalamic regulatory pathways, notably oxytocin (OXT) and gonadotropin-releasing hormone (GnRH) pathways. Middle age is associated with transcriptional declines of genes which encode OXT, GnRH and signaling components, which similarly occur in an Alzheimer's disease (AD)-like model. Therapeutically, OXT-GnRH combination is substantially more effective than individual peptides in treating AD-like disorders in male 5×FAD model. In conclusion, the hypothalamus is important for modeling age-related DNA methylation and developing hypothalamic strategies to combat AD.

Advanced Noninvasive Strategies for the Brain Delivery of Therapeutic Proteins and Peptides

Recent years have witnessed rapid progress in the discovery of therapeutic proteins and peptides for the treatment of central nervous system (CNS) diseases. However, their clinical applications have been considerably hindered by challenges such as low biomembrane permeability, poor stability, short circulation time, and the formidable blood-brain barrier (BBB). Recently, substantial improvements have been made in understanding the dynamics of the BBB and developing efficient approaches for delivering proteins and peptides to the CNS, especially by using various nanoparticles. Herein, we present an overview of the up-to-date understanding of the BBB under physiological and pathological conditions, emphasizing their effects on brain drug delivery. We summarize advanced strategies and elucidate the underlying mechanisms for delivering proteins and peptides to the brain. We highlight the developments and applications of nanocarriers in treating CNS diseases via BBB crossing. We also provide critical opinions on the limitations and obstacles of the current strategies and put forward prospects for future research.

Intranasal delivery of glucagon-like peptide-1 to the brain for obesity treatment: opportunities and challenges

INTRODUCTION

Glucagon-like peptide-1 receptor agonists (GLP-1 RAs), approved by the US FDA for obesity treatment, are typically administered subcutaneously, an invasive method leading to suboptimal patient adherence and peripheral side effects. Additionally, this route requires the drug to cross the restrictive blood-brain barrier (BBB), limiting its safety and effectiveness in weight management and cognitive addiction disorders. Delivering the drug intranasally could overcome these drawbacks.

AREAS COVERED

This review summarizes GLP-1 RAs used as anti-obesity agents, focusing on the intranasal route as a potential pathway to deliver these biomolecules to the brain. It also discusses strategies to overcome challenges associated with nasal delivery.

EXPERT OPINION

Nose-to-brain (N2B) pathways can address limitations of the subcutaneous route for GLP-1 RAs. However, peptide delivery to the brain is challenging due to nasal physiological barriers and the drug's physicochemical properties. Innovative approaches, such as cell permeation enhancers, mucoadhesive systems, and nanocarriers in nasal formulations, along with efficient drug delivery devices, show promising preclinical results. Despite this, successful preclinical data does not guarantee clinical effectiveness, highlighting the need for comprehensive clinical investigations to optimize formulations and fully utilize the nose-to-brain interface for peptide delivery.

Cell-penetrating peptides for transmucosal delivery of proteins

Enabling non-invasive delivery of proteins across the mucosal barriers promises improved patient compliance and therapeutic efficacies. Cell-penetrating peptides (CPPs) are emerging as a promising and versatile tool to enhance protein and peptide permeation across various mucosal barriers. This review examines the structural and physicochemical attributes of the nasal, buccal, sublingual, and oral mucosa that hamper macromolecular delivery. Recent development of CPPs for overcoming those mucosal barriers for protein delivery is summarized and analyzed. Perspectives regarding current challenges and future research directions towards improving non-invasive transmucosal delivery of macromolecules for ultimate clinical translation are discussed.

Evaluation of nasal delivery systems of olanzapine by desorption electrospray ionization mass spectrometry imaging

Nose-to-brain delivery presents an attractive administration route for neuroactive drugs that suffer from compromised bioavailability or fail to pass the blood-brain barrier. However, the conventional gauge of effectiveness for intranasal delivery platforms primarily involves detecting the presence of the administered drug within the brain, with little insight into its precise localization within brain structures. This may undermine the therapeutic efficacy of drugs and hinder the design of systems that target specific brain regions. In this study, we designed two intranasal delivery systems for the antipsychotic drug, olanzapine, and evaluated its distribution in the rat brain following intranasal administration. The first evaluated system was an olanzapine-loaded microemulsion and the second one was nanoparticulate aqueous dispersion of olanzapine. Both systems exhibited characteristics that render them compatible for intranasal administration, and successfully delivered olanzapine to the brain. We further employed an ambient mass spectrometry imaging method, called desorption electrospray ionization mass spectrometry imaging, to visualize the signal intensity of olanzapine in different brain regions following the intranasal administration of these two systems. Substantial variations in the distribution patterns of olanzapine across various brain structures were revealed, potentially highlighting the importance of mass spectrometry imaging in designing and evaluating intranasal drug delivery platforms.

Stimuli-responsive nanoparticles delivered by a nasal-brain pathway alleviate depression-like behavior through extensively scavenging ROS

Depression is one of the most common mental diseases, which seriously affects patients' physical and mental health. Emerging evidence has indicated that oxidative stress (OS) is a major cause of neurodegeneration involved in the pathogenesis of depression. Consequently, targeted reactive oxygen species (ROS) elimination is regarded as a promising strategy for efficient depression therapy. In addition, insufficient brain drug delivery is the main obstacle to depression therapy owing to the presence of the blood-brain barrier (BBB). To achieve the goals of bypassing the BBB and promoting antioxidant therapy for depression, a broad-spectrum ROS scavenging NPs was rationally designed through a nasal-brain pathway developed for combined ROS scavenging and brain drug delivery. A hexa-arginine (R6) modified ROS-responsive dextran (DEX) derivate was synthesized for antidepressant olanzapine (Olz) and H2 donor amino borane (AB) loading to prepare Olz/RDPA nanoparticles (NPs). Subsequently, the NPs were dispersed into a thermoresponsive hydrogel system based on poloxamer. In vitro and in vivo results demonstrated that Olz/RDPA in situ thermoresponsive hydrogel system could effectively deliver NPs to the brain via the nasal-brain pathway and alleviate depression-like behaviors through combined ROS depletion and inhibition of 5-HT dysfunction of the oxidative stress-induced. The proposed ROS-scavenging nanotherapeutic would open a new window for depression treatment. STATEMENT OF SIGNIFICANCE: ROS is an innovative therapeutic target involving the pathology of depression whereas targeted delivery of ROS scavenging has not been achieved yet. In the current study, ROS-responsive nanoparticles (Olz/RDPA NPs) were prepared and dispersed in a thermosensitive hydrogel for delivery through the nasal-brain pathway for the treatment of depression. Sufficient ROS depletion and improvement of delivery capacity by the nasal-brain pathway effectively could reverse oxidative stress and alleviate depressive-like behavior. Collectively, these nanoparticles may represent a promising strategy for the treatment of depression.