Intranasal Delivery: Effects on the Neuroimmune Axes and Treatment of Neuroinflammation

In-depth Mechanism, Challenges, and Opportunities of Delivering Therapeutics in Brain Using Intranasal Route

Central nervous system-related disorders have become a continuing threat to human life and the current statistic indicates an increasing trend of such disorders worldwide. The primary therapeutic challenge, despite the availability of therapies for these disorders, is to sustain the drug's effective concentration in the brain while limiting its accumulation in non-targeted areas. This is attributed to the presence of the blood-brain barrier and first-pass metabolism which limits the transportation of drugs to the brain irrespective of popular and conventional routes of drug administration. Therefore, there is a demand to practice alternative routes for predictable drug delivery using advanced drug delivery carriers to overcome the said obstacles. Recent research attracted attention to intranasal-to-brain drug delivery for promising targeting therapeutics in the brain. This review emphasizes the mechanisms to deliver therapeutics via different pathways for nose-to-brain drug delivery with recent advancements in delivery and formulation aspects. Concurrently, for the benefit of future studies, the difficulties in administering medications by intranasal pathway have also been highlighted.

Intranasal delivery of stem cells labeled by nanoparticles in neurodegenerative disorders: Challenges and opportunities

Neurodegenerative disorders occur through progressive loss of function or structure of neurons, with loss of sensation and cognition values. The lack of successful therapeutic approaches to solve neurologic disorders causes physical disability and paralysis and has a significant socioeconomic impact on patients. In recent years, nanocarriers and stem cells have attracted tremendous attention as a reliable approach to treating neurodegenerative disorders. In this regard, nanoparticle-based labeling combined with imaging technologies has enabled researchers to survey transplanted stem cells and fully understand their fate by monitoring their survival, migration, and differentiation. For the practical implementation of stem cell therapies in the clinical setting, it is necessary to accurately label and follow stem cells after administration. Several approaches to labeling and tracking stem cells using nanotechnology have been proposed as potential treatment strategies for neurological diseases. Considering the limitations of intravenous or direct stem cell administration, intranasal delivery of nanoparticle-labeled stem cells in neurological disorders is a new method of delivering stem cells to the central nervous system (CNS). This review describes the challenges and limitations of stem cell-based nanotechnology methods for labeling/tracking, intranasal delivery of cells, and cell fate regulation as theragnostic labeling. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Neurological Disease.

Activation of LRP6 with HLY78 Attenuates Oxidative Stress and Neuronal Apoptosis via GSK3β/Sirt1/PGC-1α Pathway after ICH

Background

Oxidative stress and neuronal apoptosis have important roles in the pathogenesis after intracerebral hemorrhage (ICH). Previous studies have reported that low-density lipoprotein receptor-related protein 6 (LRP6) exerts neuroprotection in several neurological diseases. Herein, we investigate the role of LRP6 receptor activation with HLY78 to attenuate oxidative stress and neuronal apoptosis after ICH, as well as the underlying mechanism.

Methods

A total of 199 CD1 mice were used. ICH was induced via injection of autologous blood into the right basal ganglia. HLY78 was administered via intranasal injection at 1 h after ICH. To explore the underlying mechanism, LRP6 siRNA and selisistat, a Sirt1 selective antagonist, were injected intracerebroventricularly at 48 h before ICH induction. Neurobehavioral tests, Western blot, and immunofluorescence staining were performed.

Results

The expression of endogenous p-LRP6 was gradually increased and expressed on neurons after ICH. HLY78 significantly improved the short- and long-term neurobehavioral deficits after ICH, which was accompanied with decreased oxidative stress and neuronal apoptosis, as well as increased expression of p-GSK3β, Sirt1, and PGC-1α, as well as downregulation of Romo-1 and C-Caspase-3. LRP6 knockdown or Sirt1 inhibition abolished these effects of HLY78 after ICH.

Conclusion

Our results suggest that administration of HLY78 attenuated oxidative stress, neuronal apoptosis, and neurobehavioral impairments through the LRP6/GSK3β/Sirt1/PGC-1α signaling pathway after ICH.

Emerging concepts in the treatment of optic neuritis: mesenchymal stem cell-derived extracellular vesicles

BACKGROUND

Optic neuritis (ON) is frequently encountered in multiple sclerosis, neuromyelitis optica spectrum disorder, anti-myelin oligodendrocyte glycoprotein associated disease, and other systemic autoimmune disorders. The hallmarks are an abnormal optic nerve and inflammatory demyelination; episodes of optic neuritis tend to be recurrent, and particularly for neuromyelitis optica spectrum disorder, may result in permanent vision loss.

MAIN BODY

Mesenchymal stem cell (MSC) therapy is a promising approach that results in remyelination, neuroprotection of axons, and has demonstrated success in clinical studies in other neuro-degenerative diseases and in animal models of ON. However, cell transplantation has significant disadvantages and complications. Cell-free approaches utilizing extracellular vesicles (EVs) produced by MSCs exhibit anti-inflammatory and neuroprotective effects in multiple animal models of neuro-degenerative diseases and in rodent models of multiple sclerosis (MS). EVs have potential to be an effective cell-free therapy in optic neuritis because of their anti-inflammatory and remyelination stimulating properties, ability to cross the blood brain barrier, and ability to be safely administered without immunosuppression.

CONCLUSION

We review the potential application of MSC EVs as an emerging treatment strategy for optic neuritis by reviewing studies in multiple sclerosis and related disorders, and in neurodegeneration, and discuss the challenges and potential rewards of clinical translation of EVs including cell targeting, carrying of therapeutic microRNAs, and prolonging delivery for treatment of optic neuritis.

Current State and Future Directions of Intranasal Delivery Route for Central Nervous System Disorders: A Scientometric and Visualization Analysis

Background: The management of various central nervous system (CNS) disorders has been challenging, due to highly compact blood-brain barrier (BBB) impedes the access of most pharmacological agents to the brain. Among multiple strategies proposed to circumvent this challenge, intranasal delivery route has sparked great interest for brain targeting in the past decades. The aim of this study was to apply scientometric method to estimate the current status and future trends of the field from a holistic perspective.

Methods: All relevant publications during 1998–2020 were retrieved from the Web of Science Core Collection (SCIE, 1998-present). Two different scientometric software including VOS viewer and CiteSpace, and one online platform were used to conduct co-authorship, co-citation, and co-occurrence analysis of journals, countries, institutes, authors, references and keywords.

Results: A total of 2,928 documents, including 2,456 original articles and 472 reviews, were retrieved. Our analysis revealed a significant increasing trend in the total number of scientific publications over the past 2 decades (R² = 0.98). The United States dominated the field, reflecting in the largest amount of publications (971), the highest H-index (99), and extensive international collaboration. Jamia Hamdard contributed to most publications. Frey WH and Illum L were key researchers with the highest number of publications and citations, respectively. The International Journal of Pharmaceutics was the most influential academic journal, and Pharmacology/Pharmacy and Neurosciences/Neurology were the hottest research categories in this field. Based on keywords occurrence analysis, four main topics were identified, and the current research focus of this field has shifted from cluster 4 (pathways and mechanisms of intranasal delivery) to cluster 2 (the study of nasal drug delivery systems), especially the nanostructured and nano-sized carrier systems. Keywords burst detection revealed that the research focus on oxidative stress, drug delivery, neuroinflammation, nanostructured lipid carrier, and formulation deserves our continued attention.

Conclusion: To the authors’ knowledge, this is the first scientometric analysis regarding intranasal delivery research. This study has demonstrated a comprehensive knowledge map, development landscape and future directions of intranasal delivery research, which provides a practical and valuable reference for scholars and policymakers in this field.

Advances in intranasal application of stem cells in the treatment of central nervous system diseases

Stem cells are characterized by their self-renewal and multipotency and have great potential in the therapy of various disorders. However, the blood-brain barrier (BBB) limits the application of stem cells in the therapy of neurological disorders, especially in a noninvasive way. It has been shown that small molecular substances, macromolecular proteins, and even stem cells can bypass the BBB and reach the brain parenchyma following intranasal administration. Here, we review the possible brain-entry routes of transnasal treatment, the cell types, and diseases involved in intranasal stem cell therapy, and discuss its advantages and disadvantages in the treatment of central nervous system diseases, to provide a reference for the application of intranasal stem cell therapy.

TGR5 activation attenuates neuroinflammation via Pellino3 inhibition of caspase-8/NLRP3 after middle cerebral artery occlusion in rats

BACKGROUND

Nucleotide-binding oligomerization domain-like receptor pyrin domain-containing protein 3 (NLRP3) plays an important role in mediating inflammatory responses during ischemic stroke. Bile acid receptor Takeda-G-protein-receptor-5 (TGR5) has been identified as an important component in regulating brain inflammatory responses. In this study, we investigated the mechanism of TGR5 in alleviating neuroinflammation after middle cerebral artery occlusion (MCAO).

METHODS

Sprague-Dawley rats were subjected to MCAO and TGR5 agonist INT777 was administered intranasally 1 h after MCAO. Small interfering RNAs (siRNA) targeting TGR5 and Pellino3 were administered through intracerebroventricular injection 48 h before MCAO. Infarct volumes and neurologic scores were evaluated, and ELISA, flow cytometry, immunofluorescence staining, immunoblotting, and co-immunoprecipitation were used for the evaluations.

RESULTS

Endogenous TGR5 and Pellino3 levels increased after MCAO. TGR5 activation by INT777 significantly decreased pro-inflammatory cytokine, cleaved caspase-8, and NLRP3 levels, thereby reducing brain infarctions; both short- and long-term neurobehavioral assessments showed improvements. Ischemic damage induced the interaction of TGR5 with Pellino3. Knockdown of either TGR5 or Pellino3 increased the accumulation of cleaved caspase-8 and NLRP3, aggravated cerebral impairments, and abolished the anti-inflammatory effects of INT777 after MCAO.

CONCLUSIONS

TGR5 activation attenuated brain injury by inhibiting neuroinflammation after MCAO, which could be mediated by Pellino3 inhibition of caspase-8/NLRP3.

Think Big, Start Small: How Nanomedicine Could Alleviate the Burden of Rare CNS Diseases

The complexity and organization of the central nervous system (CNS) is widely modulated by the presence of the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCSFB), which both act as biochemical, dynamic obstacles impeding any type of undesirable exogenous exchanges. The disruption of these barriers is usually associated with the development of neuropathologies which can be the consequence of genetic disorders, local antigenic invasions, or autoimmune diseases. These disorders can take the shape of rare CNS-related diseases (other than Alzheimer's and Parkinson's) which a exhibit relatively low or moderate prevalence and could be part of a potential line of treatments from current nanotargeted therapies. Indeed, one of the most promising therapeutical alternatives in that field comes from the development of nanotechnologies which can be divided between drug delivery systems and diagnostic tools. Unfortunately, the number of studies dedicated to treating these rare diseases using nanotherapeutics is limited, which is mostly due to a lack of interest from industrial pharmaceutical companies. In the present review, we will provide an overview of some of these rare CNS diseases, discuss the physiopathology of these disorders, shed light on how nanotherapies could be of interest as a credible line of treatment, and finally address the major issues which can hinder the development of efficient therapies in that area.