Protective Effect of Insulin in Mouse Nasal Mucus Against Olfactory Epithelium Injury

Effects of Different Types of Medications on Olfactory Dysfunction in CRSwNP: A Systematic Review and Network Meta-Analysis

OBJECTIVE

To evaluate the efficacy of various pharmacological treatments for olfactory disorders in patients with chronic rhinosinusitis with nasal polyps (CRSwNP).

DATA SOURCES

PubMed, Embase, Cochrane Library, and Web of Science.

METHODS

We searched the related literature in PubMed, Embase, Cochrane Library, and Web of Science up to Aug 2024 to appraise the effects of pharmacotherapy on olfactory sensation. After that, two reviewers independently screened the retrieved articles, extracted the pertinent data, and assessed the risk of bias in the included studies. Then we used Stata 14.2 to perform a network meta-analysis.

RESULTS

Ninteen randomized controlled trials (RCTs) and 2354 participants were included. Compared with placebo, biologics demonstrated the most significant improvement in subjective olfactory dysfunction (OD) [standardized mean difference (SMD) = -0.75, 95% confidence intervals (CI) (-1.08, -0.41)]. In terms of objective olfactory function improvement, biologics also exhibited the greatest effect (SMD = 0.93, 95% CI [0.56, 1.31]). Among various biologics, dupilumab was the most effective in alleviating both subjective OD (SMD = -1.30, 95% CI [-1.51, -1.09]) and objective OD (mean difference [MD] = 11.13, 95% CI [9.91, 12.35]).

CONCLUSIONS

Our research results indicated that biologics might show better performance in terms of improving the olfactory sensation of patients with CRSwNP, particularly dupilumab. However, given the limitations of this study, future research should employ more standardized olfactory assessment methods and conduct more large-scale RCTs, ultimately guiding clinicians and patients in making informed and optimal treatment choices.

LEVEL OF EVIDENCE

NA.

Allergic Fungal Rhinosinusitis and Eosinophilic Chronic Rhinosinusitis Have Different Phenotypes in Japan

BACKGROUND

Allergic fungal rhinosinusitis (AFRS) is a subtype of chronic rhinosinusitis driven by Types 1 and 3 allergies to fungi. In Japan, it is relatively rare and characterized by prominent eosinophilic infiltration of the sinonasal mucosa, together with eosinophilic mucin containing scattered fungi in the sinus cavity. Eosinophilic chronic rhinosinusitis (eCRS) involves similar eosinophilic infiltration and shares some clinical features with AFRS. However, the clinical differences between eCRS and AFRS remain to be fully elucidated. The aim of this study was to clarify the phenotypes of eCRS and AFRS.

METHODS

This multicenter retrospective study enrolled patients with AFRS and eCRS and compared their clinical parameters. A cluster analysis was conducted to determine the phenotypes of the two diseases.

RESULTS

AFRS patients had a younger age of onset and exhibited milder computed tomography and nasal polyp scores than eCRS patients. Total IgE was significantly higher in AFRS patients than in eCRS patients, while mucosal eosinophil counts were similar. Olfactory disturbances were significantly less severe in AFRS patients compared with eCRS patients. The cluster analysis revealed three phenotypes for AFRS: one that was distinct and independent from eCRS, representing the more classically described AFRS patients, and more the other two that shared characteristics with eCRS.

CONCLUSIONS

AFRS exhibits unique clinical features compared with eCRS. Cluster analysis identified three distinct AFRS phenotypes characterized by CT findings, eosinophilic inflammation, and specific IgE levels against inhaled antigens. These findings underscore the importance of differential diagnosis and personalized treatment strategies for AFRS and eCRS.

Insulin Delivery to the Brain via the Nasal Route: Unraveling the Potential for Alzheimer's Disease Therapy

This comprehensive review delves into the potential of intranasal insulin delivery for managing Alzheimer's Disease (AD) while exploring the connection between AD and diabetes mellitus (DM). Both conditions share features of insulin signalling dysregulation and oxidative stress that accelerate inflammatory response. Given the physiological barriers to brain drug delivery, including the blood-brain barrier, intranasal administration emerges as a non-invasive alternative. Notably, intranasal insulin has shown neuroprotective effects, impacting Aβ clearance, tau phosphorylation, and synaptic plasticity. In preclinical studies and clinical trials, intranasally administered insulin achieved rapid and extensive distribution throughout the brain, with optimal formulations exhibiting minimal systemic circulation. The detailed mechanism of insulin transport through the nose-to-brain pathway is elucidated in the review, emphasizing the role of olfactory and trigeminal nerves. Despite promising prospects, challenges in delivering protein drugs from the nasal cavity to the brain remain, including enzymes, tight junctions, mucociliary clearance, and precise drug deposition, which hinder its translation to clinical settings. The review encompasses a discussion of the strategies to enhance the intranasal delivery of therapeutic proteins, such as tight junction modulators, cell-penetrating peptides, and nano-drug carrier systems. Moreover, successful translation of nose-to-brain drug delivery necessitates a holistic understanding of drug transport mechanisms, brain anatomy, and nasal formulation optimization. To date, no intranasal insulin formulation has received regulatory approval for AD treatment. Future research should address challenges related to drug absorption, nasal deposition, and the long-term effects of intranasal insulin. In this context, the evaluation of administration devices for nose-to-brain drug delivery becomes crucial in ensuring precise drug deposition patterns and enhancing bioavailability.

Structures and functions of the normal and injured human olfactory epithelium

The olfactory epithelium (OE) is directly exposed to environmental agents entering the nasal cavity, leaving OSNs prone to injury and degeneration. The causes of olfactory dysfunction are diverse and include head trauma, neurodegenerative diseases, and aging, but the main causes are chronic rhinosinusitis (CRS) and viral infections. In CRS and viral infections, reduced airflow due to local inflammation, inflammatory cytokine production, release of degranulated proteins from eosinophils, and cell injury lead to decreased olfactory function. It is well known that injury-induced loss of mature OSNs in the adult OE causes massive regeneration of new OSNs within a few months through the proliferation and differentiation of progenitor basal cells that are subsequently incorporated into olfactory neural circuits. Although normal olfactory function returns after injury in most cases, prolonged olfactory impairment and lack of improvement in olfactory function in some cases poses a major clinical problem. Persistent inflammation or severe injury in the OE results in morphological changes in the OE and respiratory epithelium and decreases the number of mature OSNs, resulting in irreversible loss of olfactory function. In this review, we discuss the histological structure and distribution of the human OE, and the pathogenesis of olfactory dysfunction associated with CRS and viral infection.

An overview of in vitro and in vivo techniques for characterization of intranasal protein and peptide formulations for brain targeting

The surge in neurological disorders necessitates innovative strategies for delivering active pharmaceutical ingredients to the brain. The non-invasive intranasal route has emerged as a promising approach to optimize drug delivery to the central nervous system by circumventing the blood-brain barrier. While the intranasal approach offers numerous advantages, the lack of a standardized protocol for drug testing poses challenges to both in vitro and in vivo studies, limiting the accurate interpretation of nasal drug delivery and pharmacokinetic data. This review explores the in vitro experimental assays employed by the pharmaceutical industry to test intranasal formulation. The focus lies on understanding the diverse techniques used to characterize the intranasal delivery of drugs targeting the brain. Parameters such as drug release, droplet size measurement, plume geometry, deposition in the nasal cavity, aerodynamic performance and mucoadhesiveness are scrutinized for their role in evaluating the performance of nasal drug products. The review further discusses the methodology for in vivo characterization in detail, which is essential in evaluating and refining drug efficacy through the nose-to-brain pathway. Animal models are indispensable for pre-clinical drug testing, offering valuable insights into absorption efficacy and potential variables affecting formulation safety. The insights presented aim to guide future research in intranasal drug delivery for neurological disorders, ensuring more accurate predictions of therapeutic efficacy in clinical contexts.

A Comprehensive Review on Nanomedicine: Promising Approach for Treatment of Brain Tumor through Intranasal Administration

Brain tumors have become one of the deadliest cancers; however, their treatment is still limited by conventional approaches. Brain tumors, among other CNS diseases, are the most lethal form of cancer due to ineffective diagnosis and profiling. The major limiting factor in treating brain tumors is the blood-brain barrier (BBB), and the required therapeutic concentration is not achieved. Hence, most drugs are prescribed at higher doses, which have several unwanted side effects. Nanotechnology has emerged as an interesting and promising new approach for treating neurological disorders, including brain tumors, with the potential to overcome concerns related to traditional therapeutic approaches. Moreover, biomimetic nanomaterials have been introduced to successfully cross the blood-brain barrier and be consumed by deep skin cancer for imaging brain tumors using multimodal functional nanostructures for more specific and reliable medical assessment. These nanomedicines can address several challenges by enhancing the bioavailability of therapeutics through controlled pharmacokinetics and pharmacodynamics. Further nasal drug delivery has been considered as an alternative approach for the brain's targeting for the treatment of several CNS diseases. A drug can be directly delivered to the brain by bypassing the BBB through intranasal administration. This review discusses intranasal nanomedicine-based therapies for brain tumor targeting, which can be explored from different perspectives.