Updated epithelial barrier dysfunction in chronic rhinosinusitis: Targeting pathophysiology and treatment response of tight junctions

PM2.5 exacerbates nasal epithelial barrier dysfunction in allergic rhinitis by inducing NLRP3-mediated pyroptosis via the AhR/CYP1A1/ROS axis

Fine particulate matter (PM2.5), a major air pollutant, plays a critical role in exacerbating respiratory diseases such as allergic rhinitis (AR) by inducing inflammation. While its association with AR is well established, the precise mechanisms by which PM2.5 triggers pyroptosis and compromises nasal epithelial barrier integrity remain unclear. This study investigates the role of PM2.5 in promoting pyroptosis in nasal epithelial cells and its contribution to AR pathogenesis. Clinical analysis revealed significantly elevated levels of NLRP3 inflammasomes and pyroptosis-related proteins in the nasal mucosa of patients with AR compared with the control group. In vitro and in vivo experiments further demonstrated that PM2.5 exposure led to a dose-dependent increase in these markers in nasal epithelial cells and AR mouse models. Functional studies using NLRP3 agonists and inhibitors confirmed that PM2.5 induces NLRP3-mediated pyroptosis, resulting in tight junction protein degradation and compromised epithelial barrier integrity. Mechanistic investigations showed that PM2.5 activates the aryl hydrocarbon receptor (AhR) pathway, driving the transcription of cytochrome P450 1A1 (CYP1A1) and increasing reactive oxygen species (ROS) production. Notably, AhR downregulation alleviated PM2.5-induced pyroptosis and epithelial barrier dysfunction, whereas CYP1A1 overexpression reversed these protective effects, highlighting the pivotal role of the AhR/CYP1A1/ROS axis in mediating PM2.5-induced epithelial damage. In conclusion, this study uncovers a novel mechanism by which PM2.5 promotes NLRP3-mediated pyroptosis through the AhR/CYP1A1/ROS signaling pathway, ultimately leading to epithelial barrier disruption and AR exacerbation. These findings highlight the urgent need for strategies to minimize PM2.5 exposure and mitigate its detrimental effects on respiratory health.

Advanced oral drug delivery systems for gastrointestinal targeted delivery: the design principles and foundations

Oral administration has long been considered the most convenient method of drug delivery, requiring minimal expertise and invasiveness. Unlike injections, it avoids discomfort, wound infections, and complications, leading to higher patient compliance. However, the effectiveness of oral delivery is often hindered by the harsh biological barriers of the gastrointestinal tract, which limit the bioaccessibility and bioavailability of drugs. The development of oral drug delivery systems (ODDSs) represents a critical area for the advancement of pharmacotherapy. This review highlights the characteristics and precise targeting mechanisms of ODDSs. It first examines the unique properties of each gastrointestinal compartment, including the stomach, small intestine, intestinal mucus, intestinal epithelial barrier, and colon. Based on these features, it outlines the targeting strategies and design principles for ODDSs aimed at overcoming gastrointestinal barriers to enhance disease treatment. Lastly, the review discusses the challenges and potential future directions for ODDS development, emphasizing their importance for advancing drug delivery technologies and accelerating their future growth.

The characterization and validation of regulated cell death-related genes in chronic rhinosinusitis with nasal polyps

BACKGROUND

Regulated cell death (RCD), a genetically controlled process mediated by specialized molecular pathways (commonly termed programmed cell death), plays pivotal roles in diverse pathophysiological processes. However, the landscape and functional implications of RCD subtypes in chronic rhinosinusitis with nasal polyps (CRSwNP) remain poorly characterized. This study aimed to systematically investigate the involvement of RCD mechanisms in the pathogenesis and progression of CRSwNP.

METHODS

Transcriptomic datasets (GSE136825, GSE23552, GSE198950, GSE196169, GSE156285) related to CRSwNP were retrieved from the Gene Expression Omnibus (GEO) database. A comprehensive panel of 18 RCD-associated gene sets was compiled through a systematic literature review. Gene set variation analysis (GSVA) was employed to profile RCD activation patterns in CRSwNP. Integrative bioinformatics approaches including weighted gene co-expression network analysis (WGCNA) and least absolute shrinkage and selection operator (LASSO) regression were implemented to identify hub RCD-related genes and construct a cell death index (CDI). Single-cell RNA sequencing (scRNA-seq) data were analyzed to map RCD dynamics across cellular subpopulations. Clinical validation was performed using qRT-PCR quantification of key genes in nasal polyp/inferior turbinate tissues, with the concurrent assessment of symptom severity via visual analogue scale (VAS) scores.

RESULTS

GSVA revealed significant upregulation of 8 RCD subtypes in CRSwNP: apoptosis, ferroptosis, necroptosis, entotic cell death, lysosome-dependent cell death, NETosis, immunogenic cell death, and anoikis. Pathway enrichment analysis demonstrated that RCD-related differentially expressed genes were predominantly involved in epithelial-mesenchymal transition (EMT) and immune-inflammatory regulation. Furthermore, the WGCNA algorithm and LASSO analysis identified 8 key cell death genes (PTHLH, GRINA, S100A9, SCG2, HMOX1, RNF183, TYROBP, SEMA7A), which were utilized to construct the cell death-related index (CDI). In training and validation cohorts, the CDI was significantly elevated in CRSwNP compared to control and exhibited high diagnostic performance, with elevated scores correlating with enhanced immune cell infiltration. Single-cell resolution analysis uncovered cell type-specific RCD activation patterns. Clinical validation confirmed significantly higher expression of S100A9, PTHLH, and HMOX1 in eosinophilic versus non-eosinophilic polyps. Notably, expression levels of PTHLH, S100A9, HMOX1, GRINA, and TYROBP showed strong positive correlations with VAS scores.

CONCLUSIONS

Our investigation delineates an RCD activation signature in CRSwNP pathogenesis, characterized by 8 key cell death modalities and their regulatory genes. The novel CDI exhibits promising diagnostic potential, while mechanistic insights suggest RCD pathways may drive disease progression through EMT potentiation and inflammatory cascade amplification. These findings provide a framework for developing RCD-targeted therapeutic strategies in CRSwNP.

A long-term mixed eosinophilic and neutrophilic chronic rhinosinusitis C57BL/6 mouse model with neuroinflammation, olfactory dysfunction and anxiety-like behaviors

BACKGROUND

Chronic rhinosinusitis (CRS) is a heterogeneous condition characterized by persistent inflammation and high recurrence rates. The mixed granulocytic endotype, marked by increased eosinophils and neutrophils, is particularly refractory and prone to relapse.

OBJECTIVE

This study aimed to evaluate the papain-induced mouse model for investigating the more refractory mixed granulocytic CRS endotype, characterized by elevated eosinophils and neutrophils.

METHODS

Male C57BL/6 mice were intranasally administered papain for 11 days to induce CRS. Cytokine profiles, nasal tissue histology, olfactory bulb analysis, assessments of olfactory function, cognition, anxiety-like and depression-like behaviors were performed at 30, 60, and 90 days post-treatment.

RESULTS

A long-term mixed eosinophilic and neutrophilic CRS model was successfully established, showing elevated IgE, IL-4, IL-5, IL-13, IL-33, TSLP, and TNF-α in nasal lavage fluid, alongside infiltration of eosinophils and neutrophils in both olfactory and respiratory regions. Chronic pathology included increased mast cells, goblet cells, basal cells, mucus hyperproduction, and epithelial damage, persisting up to 90 days, with partial improvement observed at the 60-day mark. Brain analysis revealed ongoing neuroinflammation, olfactory dysfunction, and anxiety-like behaviors in CRS mice, without signs of cognitive impairment or depression-like behaviors.

CONCLUSIONS

This study phenotypically delineated a long-term mixed eosinophilic and neutrophilic CRS mouse model, demonstrating sustained neuroinflammation, olfactory dysfunction, and anxiety-like behaviors following short-term papain exposure. These findings highlighted the role of mixed inflammation in CRS and provided a time-efficient platform for further exploration of its pathogenesis and mind-brain-body interactions.

Gene Expression of Extracellular Matrix Proteins, MMPs, and TIMPs in Post-Operative Tissues of Chronic Rhinosinusitis Patients

Chronic rhinosinusitis (CRS) is a persistent inflammatory condition of the sinus mucosa characterized by significant tissue remodeling. This study aimed to evaluate the gene expression of extracellular matrix (ECM) proteins, matrix metalloproteinases (MMPs), and tissue inhibitors of metalloproteinases (TIMPs) in post-operative tissues of CRS patients. A total of 30 patients diagnosed with CRS, divided into CRSwNP (with nasal polyps) and CRSsNP (without nasal polyps) groups, were compared with a control group of 10 individuals undergoing nasal surgeries for non-CRS conditions. Gene expression analysis was conducted using quantitative real-time PCR, and plasma cytokine levels were measured via ELISA. Results indicated significantly higher expression of collagen I, collagen III, fibronectin, vimentin, periostin, and tenascin C in CRS tissues, especially in CRSsNP patients. Conversely, elastin expression was markedly lower. MMP-2, MMP-9, TIMP-1, and TIMP-2 expression was significantly altered, with CRSsNP showing lower levels compared to CRSwNP and controls. TGF-β1 expression was elevated in both CRS groups, particularly in CRSsNP, highlighting its role in fibrosis and ECM remodeling. Additionally, increased plasma concentrations of TSLP and TGF-β1 suggest epithelial activation and immune dysregulation in CRS. These findings underscore distinct remodeling profiles in CRS endotypes, emphasizing the need for targeted therapeutic strategies based on molecular phenotyping. Understanding ECM dysregulation and inflammatory pathways in CRS may lead to improved, individualized treatment approaches.

Exploring the comorbidity association and biological mechanisms of chronic rhinosinusitis and chronic obstructive pulmonary disease

Although chronic rhinosinusitis (CRS) and chronic obstructive pulmonary disease (COPD) are both common chronic inflammatory diseases, the interaction between their comorbidities remains poorly understood within the unified airway disease framework. This study, for the first time, integrated multi-omics analysis and large-scale epidemiological data to explore their common mechanisms and clinical significance. The NHANES database was used for analysis, and multivariate logistic regression was employed to assess the comorbidity risk of CRS and COPD. Machine-learning models (glmnet, ranger, and xgboost) were used to analyze the NHANES data to determine the best model. Subsequently, Mendelian randomization(MR) was applied to explore relevant associations. Additionally, CRS and COPD datasets from GEO were further analyzed to identify potential targets. The NHANES analysis showed a significant association between CRS and COPD, with MR results indicating that CRS significantly increased the risk of COPD. Multi-omics integration revealed that C3 and CD163 are core targets in CRS/COPD patients. The ranger model was identified as the most suitable in this study. This study provides new evidence that CRS is an independent risk factor for COPD and establishes a unified airway mechanism centered on C3-CD163-mediated inflammation. These findings advance the "one airway, one disease" paradigm and support a dual-target therapeutic strategy.

Identification of DIO2 as a Molecular Therapeutic Target for Depression in Chronic Rhinosinusitis: A Comprehensive Bioinformatics and Experimental Study

Chronic rhinosinusitis (CRS) and depression are both common conditions with significant socioeconomic impact. The high co-occurrence of depression in CRS patients suggests a common pathophysiology, but the mechanisms are unclear. This study aimed to identify potential molecular links between the two conditions. We retrieved gene expression datasets for CRS and depression from the GEO database. Using differentially expressed genes (DEGs) analysis and weighted gene co-expression network analysis (WGCNA), we identified co-expression genes associated with CRS and depression. Enrichment analyses including GO, KEGG, and GSEA were performed to explore biological pathways. Machine learning algorithms including random forest and LASSO regression were engaged to screen for shared hub genes predictive of CRS and depression. Single-cell RNA sequencing (scRNA-seq) data were analyzed to delineate the expression profiles of the shared hub genes across different cell types. Animal experiments were employed to validate the role of core genes in CRS-related depression. We identified five shared hub genes: CHRDL1, DIO2, HSD17B6, PDE3A, and PLA2G5, with the TGF-β signaling, cytokine-cytokine interaction receptors, and cell adhesion as key biological pathways. DIO2, as identified by machine learning, is a promising diagnostic biomarker for CRS and depression. The scRNA-seq analysis showed that DIO2 is primarily expressed in neurons and astrocytes. Animal experiments showed that overexpression of DIO2 improved the depressive-like behaviors in CRS mice. This study sheds new light on the molecular basis of the comorbidity between CRS and depression. DIO2 is a potential diagnostic and therapeutic target for CRS patients with comorbid depression.

Polyphenols-rich Portulaca oleracea L. (purslane) alleviates ulcerative colitis through restiring the intestinal barrier, gut microbiota and metabolites

Ulcerative colitis (UC) is a recurrent intestinal disease caused by a complex of factors, and there are serious adverse effects and tolerance problems associated with the current long-term use of therapeutic drugs. The development of natural food sources and multi-targeted drugs for the treatment of UC is imminent. Portulaca oleracea L. (PO), as a vegetable, has been shown in studies to have an anti-UC effects. However, the relationship between the abundant active ingredients contained in Portulaca oleracea L. and the improvement of intestinal barrier, gut microbiota and metabolites is unclear. In the present study, Portulaca oleracea L. which was found to be rich in phenolic acid-based active ingredients, were effective in alleviating dextran sulfate sodium (DSS)-induced body weight loss, disease activity index (DAI) score and colon length in mice. It also decreased C-reactive protein (CRP) and myeloperoxidase (MPO) responses, reduced the permeation of fluorescein isothiocyanate (FITC)-dextran, lipopolysaccharide (LPS) and evans blue (EB), and improved histopathological scores. Meanwhile, in vitro and in vivo validation revealed the protective effects of purslane on the intestinal barrier indicators ZO-1, Occludin and Claudin-1, and inhibited the expression of inflammation-associated iNOS and NLRP3 proteins through the NF-κB signaling pathway. In addition, purslane increased the diversity of the intestinal flora, enhancing the proportion of the genera Butyricoccus, Dorea and Bifidobacterium and decreasing the percentage of Bacteroides, Turicibacter and Parabacteroides. Serum metabolomics analysis showed that the imbalance of 39 metabolites was significantly reversed after PO deployment. Enrichment analysis showed that Pentose phosphate pathway and Pyruvate metabolism pathway were the key pathways of PO against UC. Overall, purslane effectively improved the intestinal barrier disruption and intestinal inflammation by inhibiting the NF-κB signaling pathway, and adjusted the disorder of gut microbiota and metabolites to exert anti-UC effects.

Systemic barrier dysfunction in type 2 inflammation diseases: perspective in the skin, airways, and gastrointestinal tract

The epithelial barrier in different organs is the first line of defense against environmental insults and allergens, with type 2 immunity serving as a protective function. Genetic factors, and biological and chemical insults from the surrounding environment altered regulate epithelial homeostasis through disruption of epithelial tight junction proteins or dilated intercellular spaces. Recent studies suggest that epithelial barrier dysfunction contributes to pathologic alteration in diseases with type 2 immune dysregulation including (but not limited to) atopic dermatitis, prurigo nodularis, asthma, chronic rhinosinusitis with nasal polyps, and eosinophilic esophagitis. In this review, we summarized current understanding of dysfunction of barrier and its interaction with type 2 inflammation across different organs, and discussed the role of epithelial barrier disruption in the pathogenesis of type 2 inflammation. In addition, recent progresses of emerging barrier restorative therapies are reviewed.

Type 2 immunity in allergic diseases

Significant advancements have been made in understanding the cellular and molecular mechanisms of type 2 immunity in allergic diseases such as asthma, allergic rhinitis, chronic rhinosinusitis, eosinophilic esophagitis (EoE), food and drug allergies, and atopic dermatitis (AD). Type 2 immunity has evolved to protect against parasitic diseases and toxins, plays a role in the expulsion of parasites and larvae from inner tissues to the lumen and outside the body, maintains microbe-rich skin and mucosal epithelial barriers and counterbalances the type 1 immune response and its destructive effects. During the development of a type 2 immune response, an innate immune response initiates starting from epithelial cells and innate lymphoid cells (ILCs), including dendritic cells and macrophages, and translates to adaptive T and B-cell immunity, particularly IgE antibody production. Eosinophils, mast cells and basophils have effects on effector functions. Cytokines from ILC2s and CD4+ helper type 2 (Th2) cells, CD8 + T cells, and NK-T cells, along with myeloid cells, including IL-4, IL-5, IL-9, and IL-13, initiate and sustain allergic inflammation via T cell cells, eosinophils, and ILC2s; promote IgE class switching; and open the epithelial barrier. Epithelial cell activation, alarmin release and barrier dysfunction are key in the development of not only allergic diseases but also many other systemic diseases. Recent biologics targeting the pathways and effector functions of IL4/IL13, IL-5, and IgE have shown promising results for almost all ages, although some patients with severe allergic diseases do not respond to these therapies, highlighting the unmet need for a more detailed and personalized approach.

Interaction between nasal epithelial cells and Tregs in allergic rhinitis responses to allergen via CCL1/CCR8

Background

The airway epithelial barrier is the first defence against aeroallergens. Nasal epithelial cells (NECs) are vital in regulating innate and adaptive mucosal immunity in allergic rhinitis (AR). Tregs produce cytokines essential for the immunomodulatory activities in allergen immunotherapy. Understanding the relationship between NECs and Tregs in the airway hyperresponsiveness network is essential for developing novel treatments.

Methods

Using an in vitro human Treg-NEC co-culture system of AR and health control group, the chemokine expression profiles of NECs were examined using immunohistochemistry, RT-PCR, and ELISA, and functional surface markers of Tregs were detected using flow cytometric analysis. Correlation analysis was performed between cytokines derived from NECs and surface markers of CD4+CD8+Foxp3+ Tregs in the AR group after co-culture, including TSLP/CTLA4, CCL1/CTLA4, TSLP/CTLA4, TSLP/CCR8, and CCL1/CCR8.

Results

CCR8 and CTLA-4 expressions after co-culturing were higher than single culture. Following Derp1 stimulation, TSLP, IL-25 and TGF-β expressions in the AR + Derp1 group were increased. CCL1 mRNA was lower in the AR + Derp1 group than control group. In the AR + Derp1 group, TSLP was higher, and CCL1 protein levels were decreased. There were no significant differences in IL-25, TGF-β and IL-10. When Treg co-culture group added, changes were similar to that observed in pNECs. After co-culture, CCL1/CCR8 was positively correlated in AR.

Conclusion

Human pNECs can communicate with Tregs directly, CCL1/CCR8 may be the pathway between NECs and Tregs in vitro and may play a key role in the immune network of AR.

House dust mite induced mucosal barrier dysfunction and type 2 inflammatory responses via the MAPK/AP-1/IL-24 Signaling pathway in allergic rhinitis

The epithelial barrier, previously regarded only as a physical defense, is now understood to play a vital role in immune responses and the regulation of inflammation. Allergic rhinitis (AR) is a prevalent chronic inflammatory condition of the nasal mucosa, with House Dust Mite (HDM) identified as a significant inhalant allergen that can impair this barrier. IL-24 has emerged as a key cytokine in allergic diseases, involved in maintaining epithelial cell homeostasis. Nevertheless, the underlying mechanisms of these effects remain inadequately understood. This study explores HDM-induced IL-24 secretion and mucosal barrier impairment using patient and animal tissue samples. Our results confirm that HDM sensitization triggers inflammatory changes in the nasal cavity, with IL-24 acting as a key mediator of type 2 inflammation and AR severity. HDM enhances IL-24 secretion via the P38 MAPK pathway and transcription factor AP-1, while IL-24 downregulates occludin and ZO-1 expression through the STAT1/STAT3 signaling pathway, compromising barrier function and increasing permeability. Furthermore, IL-24 promotes IL-33 secretion, further exacerbating the inflammatory response in AR. These findings clarify the mechanisms of epithelial barrier disruption in HDM-sensitized allergic rhinitis and suggest that modulating the IL-24 signaling pathway may serve as a promising therapeutic strategy to restore barrier integrity in AR.

Extracellular Vesicles Are Prevalent and Effective Carriers of Environmental Allergens in Indoor Dust

The global incidence of allergic diseases is rising and poses a substantial threat to human health. Allergenic proteins released by various allergenic species play a critical role in the pathogenesis of allergic diseases and have been widely detected in the environmental matrix. However, the release, presence and interaction of environmental allergens with human body remain to be elucidated. In this study, we reported the widespread of allergen-harboring extracellular vesicles (EVs) in indoor dust from 75 households across five provinces in China. Particle size and abundance of EVs were correlated with specific environmental factors. EVs showed long persistence and high resistance to environmental stress. Metagenomics and metaproteomics data revealed that most indoor allergenic species released allergens within the EVs into dust. A higher abundance of allergenic species and their derived EVs was observed in urban areas compared to rural areas. ELISA confirmed the allergenic activity of the EV-associated allergens. Allergens are common components and even markers of EVs, as evidenced by the data compilation of various allergenic species. The proportion of EV-associated allergens varied across species. EVs facilitated allergen entry into epithelial cells. Intranasally administered EVs can be rapidly transported to the lungs and gastrointestinal tract. EV-associated allergens exhibited higher allergenicity compared with non-EV allergens. Our findings elucidate a vesicle pathway through which environmental allergens are released, persist, and trigger allergic responses within EVs.

Thymic Stromal Lymphopoietin (TSLP): Evidence in Respiratory Epithelial-driven Diseases Including Chronic Rhinosinusitis with Nasal Polyps

PURPOSE OF THE REVIEW

Thymic stromal lymphopoietin (TSLP) is increasingly recognized for its pivotal role in the pathogenesis of various epithelial-driven chronic inflammatory diseases. This review navigates the existing evidence on TSLP, with a particular focus on asthma, before delving into the current understanding of its role in chronic rhinosinusitis with nasal polyps (CRSwNP). We explore the role of TSLP in the pathogenesis of asthma and CRSwNP, two conditions often interconnected and collectively referred to as"Global Airway Disease". Additionally, this review assesses the therapeutic potential of TSLP inhibition as a treatment option for both CRSwNP and asthma. A systematic literature search was conducted; selected publications were used to describe the biology of TSLP, including its expression and diverse effects on inflammation.

RECENT FINDINGS

The role of TSLP in asthma is well established and supported by the efficacy of tezepelumab, the first anti-TSLP monoclonal antibody approved for both type 2 (T2)-high and T2-low severe asthma. TSLP may be a key contributor to CRSwNP pathogenesis as evidenced by genetic and mechanistic studies in which TSLP has been shown to regulate T2 inflammation and influence non-T2 responses. Preliminary data from the NAVIGATOR trial indicate that tezepelumab may reduce CRSwNP symptoms in patients with comorbid asthma. While further research is required to clarify the extent of TSLP contribution in CRSwNP, this review highlights the potential of anti-TSLP therapies as a novel approach for managing severe, uncontrolled CRSwNP. If these preliminary findings are confirmed, targeting TSLP could become a promising strategy to treat CRSwNP with or without comorbid asthma.

Quercetin restores respiratory mucosal barrier dysfunction in Mycoplasma gallisepticum-infected chicks by enhancing Th2 immune response

BACKGROUND

Mycoplasma gallisepticum (MG) has long been a pathogenic microorganism threatening the global poultry industry. Previous studies have demonstrated that the mechanism by which quercetin (QUE) inhibits the colonization of MG in chicks differs from that of antibiotics. However, the molecular mechanism by which QUE facilitates the clearance of MG remains unclear.

PURPOSE

The aim of this study was to investigate the molecular mechanism of MG clearance by QUE, with the expectation of providing new options for the treatment of MG.

METHODS

A model of MG infection in chicks and MG-induced M1 polarization in HD-11 cells were established. The mechanism of QUE clearance of MG was investigated by evaluating the relationship between tracheal mucosal barrier integrity, antibody levels, Th1/Th2 immune balance and macrophage metabolism and M1/M2 polarization balance. Furthermore, network pharmacology and molecular docking techniques were employed to explore the potential molecular pathways connecting QUE, M2 polarization, and fatty acid oxidation (FAO).

RESULTS

The findings indicate that QUE remodels tracheal mucosal barrier function by regulating tight junctions and secretory immunoglobulin A (sIgA) expression levels. This process entails the regulatory function of QUE on the Th1/Th2 immune imbalance that is induced by MG infection in the tracheal mucosa. Moreover, QUE intervention impeded the M1 polarization of HD-11 cells induced by MG infection, while simultaneously promoting M2 polarization through the induction of FAO. Conversely, inhibitors of the FAO pathway impede this effect. The results of computer network analysis suggest that QUE may induce FAO via the PI3K/AKT pathway to promote M2 polarization. Notably, inhibition of the PI3K/AKT pathway was found to effectively inhibit M2 polarization in HD-11 cells, while having a limited effect on FAO.

CONCLUSIONS

QUE promotes M2 polarization of HD-11 cells to enhance Th2 immune response through FAO and PI3K/AKT pathways, thereby restoring tracheal mucosal barrier function and ultimately inhibiting MG colonization.

The epithelial era of asthma research: knowledge gaps and future direction for patient care

The Epithelial Science Expert Group convened on 18-19 October 2023, in Naples, Italy, to discuss the current understanding of the fundamental role of the airway epithelium in asthma and other respiratory diseases and to explore the future direction of patient care. This review summarises the key concepts and research questions that were raised. As an introduction to the epithelial era of research, the evolution of asthma management throughout the ages was discussed and the role of the epithelium as an immune-functioning organ was elucidated. The role of the bronchial epithelial cells in lower airway diseases beyond severe asthma was considered, as well as the role of the epithelium in upper airway diseases such as chronic rhinosinusitis. The biology and application of biomarkers in patient care was also discussed. The Epithelial Science Expert Group also explored future research needs by identifying the current knowledge and research gaps in asthma management and ranking them by priority. It was identified that there is a need to define and support early assessment of asthma to characterise patients at high risk of severe asthma. Furthermore, a better understanding of asthma progression is required. The development of new treatments and diagnostic tests as well as the identification of new biomarkers will also be required to address the current unmet needs. Finally, an increased understanding of epithelial dysfunction will determine if we can alter disease progression and achieve clinical remission.

Saccharomyces boulardii alleviates allergic asthma by restoring gut microbiota and metabolic homeostasis via up-regulation of METTL3 in an m6A-dependent manner

BACKGROUND

Allergic asthma is a heterogeneous disease and new strategies are needed to prevent or treat this disease. Studies have shown that probiotic interventions are effective in preventing asthma. Here, we investigated the impact of Saccharomyces boulardii (S. boulardii) on ovalbumin (OVA)-induced allergic asthma in mice, as well as the underlying mechanisms.

METHODS

First, we constructed a mouse asthma model using OVA and given S. boulardii intervention. Next, we measured N6-methyladenosine (m6A) levels in lung injury tissues. 16 s rRNA was employed to identify different gut microbiota in fecal samples. The analysis of differential metabolites in feces was performed by non-targeted metabolomics. Pearson correlation coefficient was utilized to analyze correlation between gut microbiota, metabolites and methyltransferase-like 3 (METTL3). Finally, we collected mouse feces treated by OVA and S. boulardii intervention for fecal microbiota transplantation (FMT) and interfered with METTL3.

RESULTS

S. boulardii improved inflammation and oxidative stress and alleviated lung damage in asthmatic mice. In addition, S. boulardii regulated m6A modification levels in asthmatic mice. 16 s rRNA sequencing showed that S. boulardii remodeled gut microbiota homeostasis in asthmatic mice. Non-targeted metabolomics analysis showed S. boulardii restored metabolic homeostasis in asthmatic mice. There was a correlation between gut microbiota, differential metabolites, and METTL3 analyzed by Pearson correlation. Additionally, through FMT and interference of METTL3, we found that gut microbiota mediated the up-regulation of METTL3 by S. boulardii improved inflammation and oxidative stress in asthmatic mice, and alleviated lung injury.

CONCLUSIONS

S. boulardii alleviated allergic asthma by restoring gut microbiota and metabolic homeostasis via up-regulation of METTL3 in an m6A-dependent manner.