Airway smooth muscle pathophysiology in asthma

Procyanidin B2 mitigate asthmatic airway remodeling by inhibiting TGF-β1-induced airway smooth muscle proliferation through ROS signaling

INTRODUCTION

Asthma is characterized by airway remodeling with increased airway smooth muscle (ASM) mass which contributes significantly to the progressive decline in lung function in asthma patients. Despite advances in therapeutic strategies targeting airway remodeling, their efficacy remains suboptimal. Procyanidin B2, antioxidants derived from grape seeds, have demonstrated potential benefits in the treatment of asthma. However, the role of procyanidin B2 involved in mitigating the process of airway remodeling and the underlying mechanisms remain unclear.

METHODS

This study investigated the effects of procyanidin B2 on ASM in asthma, with a particular focus on the molecular mechanisms involved. The markers of ASM proliferation and phenotypic switching by procyanidin B2 administration were analyzed, as well as its regulatory influence on key signaling pathways in asthma pathophysiology, to elucidate the underlying mechanism of procyanidin B2 in the control of ASM function.

RESULTS

The results showed that procyanidin B2 effectively modulated ASM proliferation and phenotypic switching. Procyanidin B2 inhibited TGF-β1-induced proliferation and phenotypic switching of ASM cells by reducing the expression of transformation markers (α-SMA, COL1A1). Blocking critical pathways such as MAPK and Akt signaling may be responsible for the suppression of ASM ROS production, which has been implicated in the pathogenesis of asthma remodeling.

CONCLUSION

This study revealed procyanidin B2 as a promising therapeutic option for asthma, highlighting the novel potential of procyanidin B2 in ASM-driven changes in this disease. These findings provide the basis and support for further research on procyanidin B2 intervention as a means to improve clinical outcomes in asthma patients.

Inverted L-shape association between a body shape index and peak expiratory flow among middle-aged and older adults: findings from the China Health and Retirement Longitudinal Study (CHARLS)

BACKGROUND

Peak expiratory flow (PEF) serves as a direct indicator of the functional status of the respiratory system. Higher body fat content, especially abdominal obesity, may relate to a deterioration in long-term respiratory function. The "A Body Shape Index" (ABSI) better assesses abdominal obesity, but its association with PEF is poorly understood.

METHODS

The analysis demonstrated data from 14,386 middle-aged and older adults from the 2015 China Health and Retirement Longitudinal Study (CHARLS). ABSI, a sex-specific metric integrating waist circumference, weight, and height via allometric modeling derived from Chinese anthropometrics, was analyzed against PEF/PEF prediction using multivariable linear and spline regressions to characterize nonlinear associations. Threshold effects, subgroup, and sensitivity analyses ensured robustness.

RESULTS

This research showed a negative relationship between ABSI and both PEF and PEF predictions. An inverted L-shaped curve in the spline analysis characterized the association between ABSI and PEF/PEF prediction across the sexes. The ABSI threshold was 0.0782 and 0.0691 in males and females, respectively.

CONCLUSIONS

Abdominal obesity negatively affects respiratory function, with ABSI thresholds varying by sex. Therefore, weight management should focus on a healthy ABSI to reduce abdominal obesity and safeguard respiratory health.

USP22/BRD4 mediated hedgehog pathway activation contributes to airway remodeling in asthma

Bromodomain-containing protein 4 (BRD4) is recognized as a member of the bromodomain and extraterminal (BET) family that is involved in the airway inflammation and airway remodeling of asthma. However, the underlying mechanisms of BRD4 in airway smooth muscle cells (ASMCs) proliferation and airway remodeling remain unclear. Primary cultured rat ASMCs and ovalbumin (OVA)-induced rat asthma models were applied to address these issues in the present study. We showed that transforming growth factor β1 (TGF-β1) increased the protein expression of ubiquitin specific peptidase 22 (USP22), which deubiquitinated BRD4 therefore increased its expression, and then resulted in the upregulation of glioma-associated oncogene homolog 1 (GLI1) and osteopontin (OPN) leading to ASMCs proliferation. We further confirmed that induction of TGF-β1 sequentially upregulated USP22, BRD4, GLI1 and OPN leading to airway remodeling in OVA-induced rat asthma models, targeting TGF-β1/USP22/BRD4/GLI1/OPN pathway axis effectively attenuated airway remodeling and asthma development. Our study provides novel sights to understand the role of TGF-β1/USP22/BRD4/GLI1/OPN axis in airway remodeling, and targeting this pathway might have potential value for the prevention and treatment of asthma.

Store-operated Ca2+ entry contributes to the ASM phenotype transition in asthma

AIM OF THE STUDY

Phenotype modulation of airway smooth muscle cells (ASMC), characterized by a shift toward a more proliferative and synthetic phenotype from contractile cells, plays a crucial role in airway remodeling in asthma. STIM1 and Orai1, key components of store-operated Ca2+ entry (SOCE), have been demonstrated to enhance ASMC proliferation and migration. This study investigated the impact of STIM1/Orai1-mediated SOCE on ASMC phenotype transition and extracellular matrix (ECM) deposition in asthma.

MATERIALS AND METHODS

The ASMCs were treated with PDGF-BB and SOCE inhibitors. Immunocytochemistry staining, enzyme-linked immunosorbent assay, and western blot assay were employed to detect the ASMC's proliferation as well as the expressions of contractile proteins, inflammatory cytokines and ECM. Moreover, the effect of SOCE repression in ECM deposition were evaluated in an asthmatic mouse model.

RESULTS

ASMCs from airways of mice were treated with PDGF-BB to induce the 'proliferative/synthetic' phenotype. We observed elevated expressions of STIM1 and Orai1 in phenotype-switched ASMCs, along with enhanced SOCE. SKF-96365 and RO2959, which target of STIM1/Orai1, could significantly inhibit SOCE activation in ASMCs. Moreover, these SOCE inhibitors mitigated the elevated proliferation rate, decreased the secretion of inflammatory cytokines and restored the reduced levels of contractile proteins in phenotype-switched ASMCs induced by PDGF-BB. Furthermore, we observed that PDGF-BB-induced 'proliferative/synthetic' ASMCs exhibited increased production of ECM components, including collagen I and fibronectin, as well as metalloproteinases (MMPs) such as MMP2 and MMP9, all of which were effectively inhibited by SKF-96365 and RO2959. In vivo experiments also demonstrated that SOCE inhibitors decreased ECM deposition and MMPs production in the asthmatic mouse model.

CONCLUSIONS

These findings underscored the significant role of STIM1/Orai1-mediated SOCE in ASMC phenotype modulation and its impact on the excessive ECM deposition driven by ASMCs. Thus, our findings suggest that STIM1/Orai1-mediated SOCE may contribute to airway remodeling in asthma.

Thoracic mobility in school-aged asthmatic children

Introduction

Asthma is a chronic respiratory condition frequently observed in childhood, which can have detrimental effects on breathing and thoracic mobility.

Objective

To describe the thoracic mobility of 6- to 11-year-old children diagnosed with asthma and compare it with that of non-asthmatic children in schools in Cali, Colombia.

Materials and methods

This cross-sectional analytical study used a non-probabilistic convenience sampling technique to assess thoracic mobility. Data were analyzed using STATA 14® statistical software. Measurement of thoracic mobility was performed using cirtometry at the axillary (CAx) and xiphoid (CX) levels according to the protocol established by Bockenhauer et al. Asthma prevalence, history, symptoms, and associated risk factors were assessed using the self-administered International Asthma and Allergies in Childhood (ISAAC) questionnaire. In addition, anthropometric measurements were collected to account for potential confounding variables.

Results

Of the 282 children enrolled, 193 met the inclusion criteria, and 11.9% were diagnosed with asthma. The asthmatic group exhibited several identified risk factors, including exposure to dust (47.8%), environmental fumes (30.4%), tobacco smoke (13%), and colds (47.8%). There were no statistically significant differences in anthropometric variables between the two groups. However, the asthmatic group showed significantly reduced thoracic mobility compared to the non-asthmatic group, especially in the CAx measurement (5.82 cm ± 2 for the non-asthmatic group vs. 5.18 cm ± 1.2 for the asthmatic group; p = 0.047).

Conclusions

Individuals diagnosed with asthma have reduced thoracic mobility compared to those without the condition.

Yanghe Pingchuan granules induce ferroptosis in airway smooth muscle cells to improve bronchial asthma via the METTL3/P53/SLC7A11 signaling pathway

BACKGROUND

Recent studies have found that ferroptosis is strongly associated with the development of bronchial asthma (BA). However, the mechanism underlying the role of ferroptosis in asthma remains unclear. Yanghe Pingchuan granules (YPG) have significant curative effect in the clinical treatment of BA. In our previous study, we found that YPG inhibit pyroptosis in the airway smooth muscle cells (ASMCs) of and reducing airway inflammation. Whether ferroptosis participated in the YPG treated BA activity is an interesting project.

PURPOSE

The aim of this study was to investigate the protective effects and the related mechanisms of YPG against BA.

METHODS

We used ultra high-performance liquid chromatograph (UPLC) to analyze the composition of YPG. Ovalbumin (OVA)-induced BA models were developed in vivo. YPG was administered to rats by gavage and ASMCs were isolated and cultured using α-SMA and CCK8 was used to assess cell viability. Gene editing, m6A RNA immunoprecipitation (MeRIP), western blotting, RT-qPCR, and transmission electron microscopy (TEM) was used to assess ferroptosis protein and mRNA expression in ASMCs. Further, the mechanism of YPG-induced regulation of ferroptosis in ASMCs via the METTL3/P53/SLC7A11 signaling axis was interrogated. BA rats were used to verify the therapeutic effects and mechanism of YPG. Moreover, hematoxylin and eosin staining was used to evaluate pathological changes using animal samples, while immunofluorescence, western blotting, RT-qPCR, and TEM were used to verify the mechanism by which YPG improved BA through the METTL3/P53/SLC7A11 signaling axis.

RESULTS

Qualitative analysis revealed seven major components in YPG. Our in vivo and in vitro data confirm that YPG significantly induced ferroptosis in ASMCs. YPG treatment effectively increased the expression of Fe2+, P53, and PTGS2, while decreasing SLC7A11, GPX4, and FTH1 expression. Moreover, TEM data revealed that YPG-induced mitochondrial membrane rupture and ridge disappearance. Additionally, YPG significantly increased METTL3 expression levels and upregulated the levels of P53 m6A, thus promoting its degradation. Notably, overexpression of METTL3 and P53 induces ferroptosis of ASMCs BA rats.

CONCLUSION

We show that YPG may induce ferroptosis of ASMCs in BA rats by activating the METTL3/P53/SLC7A11 signaling pathway, thus alleviating disease symptoms.

Oxidative stress in asthma pathogenesis: mechanistic insights and implications for airway smooth muscle dysfunction

Airway smooth muscle (ASM) dysfunction is a key factor in the narrowing of airways in asthma patients, characterized by excessive secretion of inflammatory factors, increased mass, and amplified contractile responses. These pathological features are instrumental in the propagation of airway inflammation, structural remodeling, and the escalation of airway hyperresponsiveness (AHR), which are also principal factors underlying the limitations of current therapeutic strategies. In asthmatic ASM, an imbalance between oxidant production and antioxidant defenses culminates in oxidative stress, which is involved in the excessive secretion of inflammatory factors, increased mass, and amplified contractile responses of ASM, and is a critical etiological factor implicated in the dysregulation of ASM function. The molecular pathways through which oxidative stress exerts its effects on ASM in asthma are multifaceted, with the Nrf2/HO-1, MAPK, and PI3K/Akt pathways being particularly noteworthy. These characteristic pathways play a potential role by connecting with different upstream and downstream signaling molecules and are involved in the amplification of ASM inflammatory responses, increased mass, and AHR. This review provides a comprehensive synthesis of the phenotypic expression of ASM dysfunction in asthma, the interplay between oxidants and antioxidants, and the evidence base and molecular underpinnings linking oxidative stress to ASM dysfunction. Given the profound implications of ASM dysfunction on the airflow limitation in asthma and the seminal role of oxidative stress in this process, a deeper exploration of these mechanisms is essential for unraveling the pathogenesis of asthma and may offer novel perspectives for its prophylaxis and management.

Breviscapine Attenuates Lipopolysaccharide-Induced Airway Dysfunction in Normal Human Bronchial Epithelial Cells by Suppressing the TLR4/MyD88 Signaling Pathway

Pediatric asthma is a common chronic respiratory disorder characterized by airway inflammation and hyperresponsiveness. Breviscapine (Bre) is a natural flavonoid with a broad spectrum of pharmacological activities. Previous studies have found that Bre exerts a protective effect on inflammation in airway and lung tissues. However, the effect of Bre on asthma has not yet been reported. The effects of Bre on asthmatic airway dysfunction were investigated in lipopolysaccharide (LPS)-induced normal human bronchial epithelial cells (NHBEs). Cell viability was determined by CCK-8 assay. Secretion levels of cytokines (IL-1β and IL-6) and chemokine (MCP-1) in the supernatant of NHBEs were measured by using ELISA. Whether Bre could influence LPS-caused oxidative stress in NHBEs was evaluated by detecting malondialdehyde (MDA) production and activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). RT-PCR was applied to determine the mRNA levels of mucin 5 AC (MUC5AC), collagen I (Col-I), and fibronectin (FN). Western blotting was performed to assess the expression levels of toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88), and TNF receptor associated factor 6 (TRAF6). To further confirm the role of TLR4/MyD88 signaling pathway, TLR4-overexpressing cells were constructed. Results showed that Bre attenuated LPS-induced inflammatory responses with decreased release of IL-1β, IL-6, and MCP-1 in NHBEs. The oxidative status in LPS-stimulated NHBEs was suppressed by Bre treatment, as shown by reduced MDA production and increased activities of SOD and GSH-Px. Bre also attenuated LPS-induced expression of MUC5AC, Col-I, and FN. LPS induced the activation of the TLR4/MyD88 signaling pathway in NHBEs, which could be reversed by Bre treatment. Additionally, overexpression of TLR4 lessened the protective effects of Bre on LPS-stimulated NHBEs. Overall, the foregoing results suggested that the TLR4/MyD88 signaling pathway mediated a critical protective effect of Bre on LPS-induced asthmatic airway dysfunction, which provided evidence for the potential usage of Bre for the treatment of asthma.

Investigation of the mechanistic impact of CBL0137 on airway remodeling in asthma

BACKGROUND

Bronchial asthma, a chronic inflammatory airway disease, is characterized by airway remodeling, including thickening of the airway smooth muscle layer, primarily due to abnormal proliferation of airway smooth muscle cells (ASMCs). CBL0137 (Curaxin-137 hydrochloride), a histone chaperone facilitate chromatin transcription (FACT) inhibitor, has demonstrated anti-tumor properties, including inhibition of proliferation, promotion of apoptosis, and increased autophagy. However, its effects on ASMCs and airway remodeling remain unexplored.

METHODS

Asthma models were established using ovalbumin (OVA) in female C57BL/6 J mice, with therapeutic interventions using CBL0137 and budesonide. Lung tissues were analyzed using Hematoxylin and eosin (H&E), PAS, Masson's trichrome, and α-SMA immunofluorescence staining. ASMCs extracted from Sprague-Dawley rats were cultured in vitro experiments, with phenotypic changes assessed via flow cytometry. Gene and protein expressions were analyzed using RT-PCR and Western blotting.

RESULTS

CBL0137 significantly reduced airway resistance, goblet cell proliferation, alveolar collagen deposition, and airway smooth muscle layer thickening in asthmatic mice. In vitro, CBL0137 inhibited ASMC proliferation and induced apoptosis, downregulating cyclin-B1, Cdc2, and Bcl-2 while upregulating caspase-3.

CONCLUSIONS

CBL0137 mitigates airway remodeling of asthmatic mice by modulating ASMC proliferation and apoptosis, presenting a potential therapeutic strategy for asthma treatment.

Beyond Tumors: The Pivotal Role of TRIM Proteins in Chronic Non-Tumor Lung Diseases

While TRIM proteins are extensively studied in the context of lung tumors, their roles in non-tumor chronic lung diseases remain underexplored. This review delves into the emerging significance of TRIM family proteins in the pathogenesis of idiopathic pulmonary fibrosis (IPF), asthma, chronic obstructive pulmonary disease (COPD), and pulmonary hypertension (PH). TRIM proteins modulate key pathological processes, including inflammation, fibrosis, and cellular remodeling, contributing to disease progression. We highlight their potential as biomarkers and therapeutic targets, offering promising avenues for drug development in these debilitating respiratory disorders. However, the translation of these findings into clinical applications faces significant challenges. These include the dual functional nature of TRIM proteins, their context-dependent roles, the complexity of their downstream signaling networks, and the limitations of current therapeutic strategies in achieving tissue-specific targeting with minimal off-target effects. Addressing these challenges will require innovative approaches and interdisciplinary efforts to unlock the therapeutic potential of TRIM proteins in non-tumor chronic lung diseases.

CAD-Q (COPD-Asthma Differentiation Questionnaire): Performance of a new diagnostic score to differentiate between COPD and asthma in adults

BACKGROUND

Chronic obstructive pulmonary disease (COPD) and asthma are the two most prevalent chronic respiratory diseases, significantly impacting public health. Utilizing clinical questionnaires to identify and differentiate patients with COPD and asthma for further diagnostic procedures has emerged as an effective strategy to address this issue. We developed a new diagnostic tool, the COPD-Asthma Differentiation Questionnaire (CAD-Q), to differentiate between COPD and asthma in adults.

METHODS

A cross-sectional study with diagnostic test analysis was done. Relevant clinical variables for diagnosing COPD and asthma were identified through crude Odds Ratios (OR) and a logistic regression model provided adjusted ORs. The CAD-Q, including sensitivity, specificity, predictive values, likelihood ratios, and ROC-curve, was compared to the LFQ, CDQ, PUMA, "Could it be COPD," and COPD-PS questionnaires.

RESULTS

235 (52.9%) patients had COPD and 209 (47.1%) had asthma. A score ≥ 20 on the CAD-Q questionnaire showed a ROC-curve of 70% (95% CI: 65-75; p < 0.001) with a sensitivity of 83.8% (95% CI: 81.1-86.6), specificity of 47.8% (95% CI: 44.1-51.6), positive predictive value of 37.8% (95% CI: 34.2-41.5), negative predictive value of 88.7% (95% CI: 86.3-91), LR + of 1.61 (95% CI: 1.447-1.786), LR - of 0.34 (95% CI: 0.304-0.376) for diagnosing COPD. When comparing CAD-Q with other questionnaires for differentiating COPD and asthma, CAD-Q and CDQ had the highest sensitivity (83.8% and 77.9%). PUMA and "Could it be COPD" had the highest specificity (62.7% and 62.6%). CAD-Q and COPD-PS showed the highest negative predictive values (88.7% and 62.1%). CAD-Q, LFQ, and CDQ had the highest a ROC-curve (70%, 66%, and 66%).

CONCLUSION

The CAD-Q questionnaire effectively discriminated between COPD and asthma, outperforming previous tools. These findings support further research and refinement of diagnostic tools and call for validation in diverse clinical settings.

Histamine-induced cytosolic calcium mobilization in human bronchial smooth muscle cells

Histamine is a well-known mediator of bronchoconstriction. Despite the widespread use of histamine as a tool to study the bronchial smooth muscle function, the precise mechanism by which it causes calcium mobilization in bronchial smooth muscle cells remains unclear. Therefore, the current study aimed to investigate the mechanism of action of histamine in calcium mobilization in cultured human bronchial smooth muscle cells. A series of in vitro calcium imaging experiments have shown that histamine increases intracellular calcium levels in a concentration-dependent manner. The half maximum concentration of cytosolic Ca2+ peak was 3.00 ± 0.25 µM of histamine. Histamine was able to mobilize calcium from intracellular stores, even in the absence of extracellular calcium. These histamine-induced calcium elevations were completely blocked by the H1 receptor antagonist chlorpheniramine (1 µM). Histamine-induced calcium elevation was also completely inhibited by the phospholipase C (PLC) inhibitor U73122 (1 µM) and inositol 1,4,5-trisphosphate (InsP3) receptor inhibitor caffeine (20 mM). Cyanide p-(trifluoromethoxy)phenylhydrazone (1 µM) and oligomycin (1 µg/ml) effectively attenuated histamine-induced calcium release from intracellular stores. In the presence of histamine, cytosolic calcium elevation induced by reperfusion of 1.28 mM extracellular calcium after the depletion of stores was significantly inhibited by FCCP and oligomycin, unlike in the presence of thapsigargin. Based on the above results, we can conclude that histamine activates the intracellular PLC/InP3 pathway through the H1 receptor, which in turn activates the InP3 receptor present in intracellular stores to mobilize calcium in human bronchial smooth muscle cells. In addition, the mitochondria appear to be involved in the release of calcium from intracellular stores. These results provide insights into the mechanisms underlying histamine-induced calcium mobilization for bronchoconstriction under pathophysiological conditions.

N-cadherin antagonism is bronchoprotective in severe asthma models

Severe asthma induces substantial mortality and chronic disability due to intractable airway obstruction, which may become resistant to currently available therapies including corticosteroids and β-adrenergic agonist bronchodilators. A key effector of these changes is exaggerated airway smooth muscle (ASM) cell contraction to spasmogens. No drugs in clinical use effectively prevent ASM hyperresponsiveness in asthma across all severities. We find that N-cadherin, a membrane cell-cell adhesion protein up-regulated in ASM from patients with severe asthma, is required for the development of airway obstruction induced by allergic airway inflammation in mice. Inhibition of N-cadherin by ADH-1 reduced airway hyperresponsiveness independent of allergic inflammation, prevented bronchoconstriction, and actively promoted bronchodilation of airways ex vivo. ADH-1 inhibited ASM contraction by disrupting N-cadherin-δ-catenin interactions, which decreased intracellular actin remodeling. These data provide evidence for an intercellular communication pathway mediating ASM contraction and identify N-cadherin as a potential therapeutic target for inhibiting bronchoconstriction in asthma.

Integration of bioprinting advances and biomechanical strategies forin vitrolung modelling

The recent occurrence of the Covid-19 pandemic and frequent wildfires have worsened pulmonary diseases and raised the urgent need for investigating host-pathogen interactions and advancing drug and vaccine therapies. Historically, research and experimental studies have relied on two-dimensional cell culture dishes and/or animal models, which suffer from physiological differences from the human lung. More recently, there has been investigation into the use of lung-on-a-chip models and organoids, while the use of bioprinting technologies has also emerged to fabricate three-dimensional constructs or lung models with enhanced physiological relevance. Concurrently, achievements have also been made to develop biomimetic strategies for simulating thein vivobiomechanical conditions induced by lung breathing, though challenges remain with incorporating these strategies with bioprinted models. Bioprinted models combined with advanced biomimetic strategies would represent a promising approach to advance disease discovery and therapeutic development. As inspired, this article briefly reviews the recent progress of both bioprintedin vitrolung models and biomechanical strategies, with a focus on native lung tissue microstructure and biomechanical properties, bioprinted constructs, and biomimetic strategies to mimic the native environment. This article also urges that the integration of bioprinting advances and biomimetic strategies would be essential to achieve synergistic effects forin vitrolung modelling. Key issues and challenges are also identified and discussed along with recommendations for future research.

Airway epithelial cells promote in vitro airway smooth muscle cell proliferation by activating the Wnt/β-catenin pathway

Asthma is a common chronic inflammatory airway disease, imposing a substantial health and economic burden on society and individuals. Current treatments primarily focus on symptom relief and lung function improvement, often failing to address the underlying pathology. Thus, exploring new therapeutic approaches is crucial. Airway smooth muscle cells (ASMCs) play a key role in regulating airway tone and airflow, while abnormal ASMCs proliferation contributes to airway remodeling in asthma. Airway epithelial cells (AECs), serving as the first barrier against pathogens and allergens, also have critical immune functions. This study focuses on the interaction between AECs and ASMCs, as AECs are more accessible for drug delivery due to their location at the airway surface. Investigating this relationship could facilitate novel interventions targeting AECs to inhibit pathological ASMCs activity. In our experiment, we isolated ASMCs and AECs from healthy mice and found that AECs significantly promoted ASMCs proliferation in co-culture. RNA sequencing revealed that this process might be linked to the activation of the canonical Wnt signaling pathway in ASMCs. By using Wnt pathway inhibitors (endo-IWR1) and siRNA to disrupt Wnt receptors, we reversed this phenotype. This finding suggests that AECs may promote ASMCs proliferation by activating the Wnt pathway in ASMCs. The Wnt/β-catenin pathway appears to play an important role in ASMCs proliferation, indicating that future pathological studies should consider the potential involvement of the Wnt pathway in airway remodeling.

Mechanisms of mechanical stimulation in the development of respiratory system diseases

During respiration, mechanical stress can initiate biological responses that impact the respiratory system. Mechanical stress plays a crucial role in the development of the respiratory system. However, pathological mechanical stress can impact the onset and progression of respiratory diseases by influencing the extracellular matrix and cell transduction processes. In this article, we explore the mechanisms by which mechanical forces communicate with and influence cells. We outline the basic knowledge of respiratory mechanics, elucidating the important role of mechanical stimulation in influencing respiratory system development and differentiation from a microscopic perspective. We also explore the potential mechanisms of mechanical transduction in the pathogenesis and development of respiratory diseases such as asthma, lung injury, pulmonary fibrosis, and lung cancer. Finally, we look forward to new research directions in cellular mechanotransduction, aiming to provide fresh insights for future therapeutic research on respiratory diseases.

WTAP Promotes the Excessive Proliferation of Airway Smooth Muscle Cells in Asthma by Enhancing AXIN1 Levels Through the Recognition of YTHDF2

Asthma is a common chronic respiratory disease in children, the incidence rate of which has increased in recent years. Wilms tumour 1-associated protein (WTAP) is an N6-methyladenosine (m6A) methyltransferase. The purpose of this study was to explore the specific mechanism of WTAP in asthma progression, and clarify the intricate interplay between m6A modifications, WTAP, AXIN1, and their collective impact on airway smooth muscle cells (ASMCs) proliferation in asthma. Platelet-derived growth factor-BB (PDGF-BB)-treated ASMCs were used to establish an asthma model in vitro. The cell phenotype was tested using CCK-8, transwell, and wound healing assays. The expression of the Wnt signalling pathway was detected by western blotting. In addition, the relationship between WTAP/YTDHF2 and AXIN1 was assessed by a double luciferase reporter assay. Actinomycin D treatment and RT‒qPCR assays were performed to determine the mRNA stability of AXIN1. We found that WTAP was significantly increased in PDGF-BB-treated ASMCs. Knockdown of WTAP inhibited the excessive cell viability and migration of ASMCs induced by PDGF-BB. Furthermore, WTAP knockdown increased AXIN1 levels and inhibited the Wnt signalling pathway. Furthermore, WTAP knockdown decreased the m6A levels and enhanced the mRNA stability of AXIN1. WTAP overexpression showed the opposite effect. In addition, YTHDF2 was demonstrated to be the reader that recognizes the WTAP-mediated m6A modification of AXIN1. YTHDF2 knockdown enhanced the mRNA stability of AXIN1 and reversed the effect of WTAP overexpression on PDGF-BB-treated ASMCs. WTAP knockdown inhibited the excessive cell viability and migration of ASMCs by enhancing the m6A levels of AXIN1, which was further recognized by YTHDF2. The upregulation of AXIN1 mediated by the WTAP/YTHDF2 axis further inhibited the Wnt signalling pathway. Our study provides a new method for the treatment of asthma. This work not only deepens our understanding of the molecular underpinnings of asthma but also identifies potential therapeutic targets for the development of novel treatments aimed at inhibiting ASMC proliferation and alleviating asthma symptoms.

Genome-Wide DNA methylation profile analysis identifies differentially methylated loci associated with personal PM2.5 exposure in adults with asthma

Particulate matter with aerodynamic diameters ≤2.5 µm (PM2.5) is a major environmental risk factor for acute asthma exacerbation, and the underlying mechanism is not completely understood. Studies have indicated that DNA methylation is a potential mechanism linking PM2.5 to its health effects. We conducted a panel study involving 24 adult patients with asthma in Beijing,China between 2017 and 2019. PM2.5 and other atmospheric pollutant exposure data were repeatedly measured. Blood samples were collected for genome-wide DNA methylation analysis. A linear mixed-effects (LME) model was conducted to identify differentially methylated probes (DMPs) associated with PM2.5 exposure. After filtering out probes that did not meet the criteria through quality control, 811,001 CpG sites were included in the LME model, and 36 DMPs were strongly associated with personal PM2.5 exposure at false discovery rate (FDR) < 0.05, of which 22 and 14 DMPs negatively and positively correlated with personal PM2.5 exposure, respectively. Functional analysis revealed that DMPs affected smooth muscle cell contraction and development, extracellular matrix synthesis and secretion, T cell activation and differentiation, and inflammatory factor production. This study provides evidence linking personal PM2.5 exposure to genome-wide DNA methylation in adult patients with asthma. Identifying enrichment pathways can provide biological insights into the acute health effects of PM2.5.

Circular RNAs in human diseases

Circular RNAs (circRNAs) are a unique class of RNA molecules formed through back-splicing rather than linear splicing. As an emerging field in molecular biology, circRNAs have garnered significant attention due to their distinct structure and potential functional implications. A comprehensive understanding of circRNAs' functions and potential clinical applications remains elusive despite accumulating evidence of their involvement in disease pathogenesis. Recent research highlights their significant roles in various human diseases, but comprehensive reviews on their functions and applications remain scarce. This review provides an in-depth examination of circRNAs, focusing first on their involvement in non-neoplastic diseases such as respiratory, endocrine, metabolic, musculoskeletal, cardiovascular, and renal disorders. We then explore their roles in tumors, with particular emphasis on exosomal circular RNAs, which are crucial for cancer initiation, progression, and resistance to treatment. By detailing their biogenesis, functions, and impact on disease mechanisms, this review underscores the potential of circRNAs as diagnostic biomarkers and therapeutic targets. The review not only enhances our understanding of circRNAs' roles in specific diseases and tumor types but also highlights their potential as novel diagnostic and therapeutic tools, thereby paving the way for future clinical investigations and potential therapeutic interventions.

scRNA-seq identifies unique macrophage population in murine model of ozone induced asthma exacerbation

Ozone (O 3 ) inhalation triggers asthmatic airway hyperresponsiveness (AHR), but the mechanisms by which this occurs are unknown. Previously, we developed a murine model of dust mite, ragweed, and aspergillus (DRA)-induced allergic lung inflammation followed by O 3 exposure for mechanistic investigation. The present study used single cell RNA-sequencing for unbiased profiling of immune cells within the lungs of mice exposed to DRA, O 3 , or DRA+O 3 , to identify the components of the immune cell niche that contribute to AHR. Alveolar macrophages (AMs) had the greatest number of differentially expressed genes following DRA+O 3 , most of which were unique to the 2-hit exposure. Following DRA+O 3 , AMs activated transcriptional pathways related to cholesterol biosynthesis, degradation of the extracellular matrix, endosomal TLR processing, and various cytokine signals. We also identified AM and monocyte subset populations that were unique to the DRA+O 3 group. These unique AMs activated gene pathways related to inflammation, sphingolipid metabolism, and bronchial constriction. The unique monocyte population had a gene signature that suggested phospholipase activation and increased degradation of the extracellular matrix. Flow cytometry analysis of BAL immune cells showed recruited monocyte-derived AMs after DRA and DRA+O 3 , but not after O 3 exposure alone. O 3 alone increased BAL neutrophils but this response was attenuated in DRA+O 3 mice. DRA-induced changes in the airspace immune cell profile were reflected in elevated BAL cytokine/chemokine levels following DRA+O 3 compared to O 3 alone. The present work highlights the role of monocytes and AMs in the response to O 3 and suggests that the presence of distinct subpopulations following allergic inflammation may contribute to O 3 -induced AHR.

CXCL3: A key player in tumor microenvironment and inflammatory diseases

CXCL3 (C-X-C Motif Chemokine 3), a member of the C-X-C chemokine subfamily, operates as a potent chemoattractant for neutrophils, thereby orchestrating the recruitment and migration of leukocytes alongside eliciting an inflammatory response. Recent inquiries have shed light on the pivotal roles of CXCL3 in the context of carcinogenesis. In the tumor microenvironment, CXCL3 emanating from both tumor and stromal cells intricately modulates cellular behaviors through autocrine and paracrine actions, primarily via interaction with its receptor CXCR2. Activation of signaling cascades such as ERK/MAPK, AKT, and JAK2/STAT3 underscores CXCL3's propensity to favor tumorigenic processes. However, CXCL3 exhibits dualistic behaviors, as evidenced by its capacity to exert anti-tumor effects under specific conditions. Additionally, the involvement of CXCL3 extends to inflammatory disorders like eclampsia, obesity, and asthma. This review encapsulates the structural attributes, biological functionalities, and molecular underpinnings of CXCL3 across both tumorigenesis and inflammatory diseases.

Zedoarondiol inhibits human bronchial smooth muscle cell proliferation through the CAV-1/PDGF signalling pathway

Airway remodelling in lung diseases can be treated by inhibiting excessive smooth muscle cell proliferation. Zedoarondiol (Zed) is a natural compound isolated from the Chinese herb Curcuma longa. The caveolin-1 (CAV-1) is widely expressed in lung cells and plays a key role in platelet-derived growth factor (PDGF) signalling and cell proliferation. This study aims to investigate the effect of Zed on human bronchial smooth muscle cell (HBSMC) proliferation and explore its potential molecular mechanisms. We assessed the effect of Zed on the proliferation of PDGF-stimulated HBSMCs and performed proteomic analysis to identify potential molecular targets and pathways. CAV1 siRNA was used to validate our findings in vitro. In PDGF-stimulated HBSMCs, Zed significantly inhibited excessive proliferation of HBSMCs. Proteomic analysis of zedoarondiol-treated HBSMCs revealed significant enrichment of differentially expressed proteins in cell proliferation-related pathways and biological processes. Zed inhibition of HBSMC proliferation was associated with upregulation of CAV1, regulation of the CAV-1/PDGF pathway and inhibition of MAPK and PI3K/AKT signalling pathway activation. Treatment of HBSMCs with CAV1 siRNA partly reversed the inhibitory effect of Zed on HBSMC proliferation. Thus, this study reveals that zedoarondiol potently inhibits HBSMC proliferation by upregulating CAV-1 expression, highlighting its potential value in airway remodelling and related diseases.

Long non-coding RNA MEG3 knockdown represses airway smooth muscle cells proliferation and migration via sponging miR-143-3p/FGF9 in asthma

BACKGROUND

Asthma is a respiratory disease characterized by airway remodeling. We aimed to find out the role and mechanism of lncRNA MEG3 in asthma.

METHODS

We established a cellular model of asthma by inducing human airway smooth muscle cells (HASMCs) with PDGF-BB, and detected levels of lncRNA MEG3, miR-143-3p and FGF9 in HASMCs through qRT-PCR. The functions of lncRNA MEG3 or miR-143-3p on HASMCs were explored by cell transfection. The binding sites of miR-143-3p and FGF9 were subsequently analyzed with bioinformatics software, and validated with dual-luciferase reporter assay. MTT, 5-Ethynyl-2'-deoxyuridine (EdU) assay, and Transwell were used to detect the effects of lncRNA MEG3 or miR-143-3p on proliferation and migration of HASMCs. QRT-PCR and western blot assay were used to evaluate the level of proliferation-related marker PCNA in HASMCs.

RESULTS

The study found that lncRNA MEG3 negatively correlated with miR-143-3p, and miR-143-3p could directly target with FGF9. Silence of lncRNA MEG3 can suppress migration and proliferation of PDGF-BB-induced HASMCs via increasing miR-143-3p. Further mechanistic studies revealed that miR-143-3p negatively regulated FGF9 expression in HASMCs. MiR-143-3p could inhibit PDGF-BB-induced HASMCs migration and proliferation through downregulating FGF9.

CONCLUSION

LncRNA MEG3 silencing could inhibit the migration and proliferation of HASMCs through regulating miR-143-3p/FGF9 signaling axis. These results imply that lncRNA MEG3 plays a protective role against asthma.

Airway hyperresponsiveness in asthma: The role of the epithelium

Airway hyperresponsiveness (AHR) is a key clinical feature of asthma. The presence of AHR in people with asthma provides the substrate for bronchoconstriction in response to numerous diverse stimuli, contributing to airflow limitation and symptoms including breathlessness, wheeze, and chest tightness. Dysfunctional airway smooth muscle significantly contributes to AHR and is displayed as increased sensitivity to direct pharmacologic bronchoconstrictor stimuli, such as inhaled histamine and methacholine (direct AHR), or to endogenous mediators released by activated airway cells such as mast cells (indirect AHR). Research in in vivo human models has shown that the disrupted airway epithelium plays an important role in driving inflammation that mediates indirect AHR in asthma through the release of cytokines such as thymic stromal lymphopoietin and IL-33. These cytokines upregulate type 2 cytokines promoting airway eosinophilia and induce the release of bronchoconstrictor mediators from mast cells such as histamine, prostaglandin D2, and cysteinyl leukotrienes. While bronchoconstriction is largely due to airway smooth muscle contraction, airway structural changes known as remodeling, likely mediated in part by epithelial-derived mediators, also lead to airflow obstruction and may enhance AHR. In this review, we outline the current knowledge of the role of the airway epithelium in AHR in asthma and its implications on the wider disease. Increased understanding of airway epithelial biology may contribute to better treatment options, particularly in precision medicine.

Nanoplastics Penetrate Human Bronchial Smooth Muscle and Small Airway Epithelial Cells and Affect Mitochondrial Metabolism

Micro- and nanoplastic particles, including common forms like polyethylene and polystyrene, have been identified as relevant pollutants, potentially causing health problems in living organisms. The mechanisms at the cellular level largely remain to be elucidated. This study aims to visualize nanoplastics in bronchial smooth muscle (BSMC) and small airway epithelial cells (SAEC), and to assess the impact on mitochondrial metabolism. Healthy and asthmatic human BSMC and SAEC in vitro cultures were stimulated with polystyrene nanoplastics (PS-NPs) of 25 or 50 nm size, for 1 or 24 h. Live cell, label-free imaging by holotomography microscopy and mitochondrial respiration and glycolysis assessment were performed. Furthermore, 25 and 50 nm NPs were shown to penetrate SAEC, along with healthy and diseased BSMC, and they impaired bioenergetics and induce mitochondrial dysfunction compared to cells not treated with NPs, including changes in oxygen consumption rate and extracellular acidification rate. NPs pose a serious threat to human health by penetrating airway tissues and cells, and affecting both oxidative and glycolytic metabolism.

PM2.5 exposure-induced senescence-associated secretory phenotype in airway smooth muscle cells contributes to airway remodeling

Fine particulate matter (PM2.5) has been linked to increased severity and incidence of airway diseases, especially chronic obstructive pulmonary disease (COPD) and asthma. Airway remodeling is an important event in both COPD and asthma, and airway smooth muscle cells (ASMCs) are key cells which directly involved in airway remodeling. However, it was unclear how PM2.5 affected ASMCs. This study investigates the effects of PM2.5 on airway smooth muscle and its mechanism. We first showed that inhaled particulate matter was distributed in the airway smooth muscle bundle, combined with increased airway smooth muscle bundle and collagen deposition in vivo. Then, we demonstrated that PM2.5 induced up-regulation of collagen-I and alpha-smooth muscle actin (α-SMA) expression in rat and human ASMCs in vitro. Next, we found PM2.5 led to rat and human ASMCs senescence and exhibited senescence-associated secretory phenotype (SASP) by autophagy-induced GATA4/TRAF6/NF-κB signaling, which contributed to collagen-I and α-SMA synthesis as well as airway smooth muscle remodeling. Together, our results provided evidence that SASP induced by PM2.5 in airway smooth muscle cells prompted airway remodeling.

Aerobic physical training reduces severe asthma phenotype involving kinins pathway

INTRODUCTION

Aerobic physical training (APT) reduces eosinophilic airway inflammation, but its effects and mechanisms in severe asthma remain unknown.

METHODS

An in vitro study employing key cells involved in the pathogenesis of severe asthma, such as freshly isolated human eosinophils, neutrophils, and bronchial epithelial cell lineage (BEAS-2B) and lung fibroblasts (MRC-5 cells), was conducted. Additionally, an in vivo study using male C57Bl/6 mice, including Control (Co; n = 10), Trained (Exe; n = 10), house dust mite (HDM; n = 10), and HDM + Trained (HDM + Exe; n = 10) groups, was carried out, with APT performed at moderate intensity, 5x/week, for 4 weeks.

RESULTS

HDM and bradykinin, either alone or in combination, induced hyperactivation in human neutrophils, eosinophils, BEAS-2B, and MRC-5 cells. In contrast, IL-10, the primary anti-inflammatory molecule released during APT, inhibited these inflammatory effects, as evidenced by the suppression of numerous cytokines and reduced mRNA expression of the B1 receptor and ACE-2. The in vivo study demonstrated that APT decreased bronchoalveolar lavage levels of bradykinin, IL-1β, IL-4, IL-5, IL-17, IL-33, TNF-α, and IL-13, while increasing levels of IL-10, klotho, and IL-1RA. APT reduced the accumulation of polymorphonuclear cells, lymphocytes, and macrophages in the peribronchial space, as well as collagen fiber accumulation, epithelial thickness, and mucus accumulation. Furthermore, APT lowered the expression of the B1 receptor and ACE-2 in lung tissue and reduced bradykinin levels in the lung tissue homogenate compared to the HDM group. It also improved airway resistance, tissue resistance, and tissue damping. On a systemic level, APT reduced total leukocytes, eosinophils, neutrophils, basophils, lymphocytes, and monocytes in the blood, as well as plasma levels of IL-1β, IL-4, IL-5, IL-17, TNF-α, and IL-33, while elevating the levels of IL-10 and IL-1RA.

CONCLUSION

These findings indicate that APT inhibits the severe asthma phenotype by targeting kinin signaling.

The airway epithelium: an orchestrator of inflammation, a key structural barrier and a therapeutic target in severe asthma

Asthma is a disease of heterogeneous pathology, typically characterised by excessive inflammatory and bronchoconstrictor responses to the environment. The clinical expression of the disease is a consequence of the interaction between environmental factors and host factors over time, including genetic susceptibility, immune dysregulation and airway remodelling. As a critical interface between the host and the environment, the airway epithelium plays an important role in maintaining homeostasis in the face of environmental challenges. Disruption of epithelial integrity is a key factor contributing to multiple processes underlying asthma pathology. In this review, we first discuss the unmet need in asthma management and provide an overview of the structure and function of the airway epithelium. We then focus on key pathophysiological changes that occur in the airway epithelium, including epithelial barrier disruption, immune hyperreactivity, remodelling, mucus hypersecretion and mucus plugging, highlighting how these processes manifest clinically and how they might be targeted by current and novel therapeutics.

Increased Risk of New-Onset Asthma After COVID-19: A Nationwide Population-Based Cohort Study

BACKGROUND

Previous studies have suggested that respiratory virus infections may be associated with new-onset asthma. However, whether coronavirus disease 2019 (COVID-19) is associated with an increased risk of new-onset asthma remains unclear.

OBJECTIVE

We aimed to evaluate whether recent COVID-19 increases the risk of new-onset asthma and whether COVID-19 vaccination could mitigate this risk.

METHODS

We constructed 3 different study designs using the Korean National Health Insurance claim-based database: study 1: COVID-19-diagnosed subjects (COVID-19 cohort) and their matched controls; study 2: COVID-19-vaccinated subjects (vaccination cohort) and their matched controls; and study 3: vaccination cohort and their matched controls, excluding subjects diagnosed with COVID-19.

RESULTS

In study 1, 1.6% of the COVID-19 cohort and 0.7% of the matched cohort developed new-onset asthma, with incidences of 31.28 and 14.55 per 1,000 person-years, respectively (P < .001). The COVID-19 cohort had a higher risk of new-onset asthma (adjusted hazard ratio [aHR] 2.14; 95% CI 1.88-2.45) than matched controls. In study 2, the vaccination cohort had a lower risk of new-onset asthma than the matched controls (aHR 0.82; 95% CI 0.76-0.89). However, among subjects without a COVID-19 diagnosis, COVID-19 vaccination was not associated with a reduced risk of new-onset asthma in study 3 (aHR 0.95; 95% CI 0.87-1.04). In subgroup analysis, the risk of new-onset asthma was significantly lower in fully vaccinated subjects and higher in older subjects and in those with diabetes mellitus than in their counterparts.

CONCLUSIONS

The COVID-19 was associated with a higher incidence of new-onset asthma, which might be preventable by COVID-19 vaccination.

Cysteine and glycine-rich protein 2 retards platelet-derived growth factor-BB-evoked phenotypic transition of airway smooth muscle cells by decreasing YAP/TAZ activity

Cysteine and glycine-rich protein 2 (Csrp2) has emerged as a key factor in controlling the phenotypic modulation of smooth muscle cells. The phenotypic transition of airway smooth muscle cells (ASMCs) is a pivotal step in developing airway remodeling during the onset of asthma. However, whether Csrp2 mediates the phenotypic transition of ASMCs in airway remodeling during asthma onset is undetermined. This work aimed to address the link between Csrp2 and the phenotypic transition of ASMCs evoked by platelet-derived growth factor (PDGF)-BB in vitro. The overexpression or silencing of Csrp2 in ASMCs was achieved through adenovirus-mediated gene transfer. The expression of mRNA was measured by quantitative real-time-PCR. Protein levels were determined through Western blot analysis. Cell proliferation was detected by EdU assay and Calcein AM assays. Cell cycle distribution was assessed via fluorescence-activated cell sorting assay. Cell migration was evaluated using the scratch-wound assay. The transcriptional activity of Yes-associated protein (YAP)/transcriptional coactivator with PDZ-binding motif (TAZ) was measured using the luciferase reporter assay. A decline in Csrp2 level occurred in PDGF-BB-stimulated ASMCs. Increasing Csrp2 expression repressed the PDGF-BB-evoked proliferation and migration of ASMCs. Moreover, increasing Csrp2 expression impeded the phenotypic change of PDGF-BB-stimulated ASMCs from a contractile phenotype into a synthetic/proliferative phenotype. On the contrary, the opposite effects were observed in Csrp2-silenced ASMCs. The activity of YAP/TAZ was elevated in PDGF-BB-stimulated ASMCs, which was weakened by Csrp2 overexpression or enhanced by Csrp2 silencing. The YAP/TAZ activator could reverse Csrp2-overexpression-mediated suppression of the PDGF-BB-evoked phenotypic switching of ASMCs, while the YAP/TAZ suppressor could dimmish Csrp2-silencing-mediated enhancement on PDGF-BB-evoked phenotypic switching of ASMCs. In summary, Csrp2 serves as a determinant for the phenotypic switching of ASMCs. Increasing Csrp2 is able to impede PDGF-BB-evoked phenotypic change of ASMCs from a synthetic phenotype into a synthetic/proliferative phenotype through the effects on YAP/TAZ. This work implies that Csrp2 may be a key player in airway remodeling during the onset of asthma.

Asthma and COPD: A Focus on β-Agonists - Past, Present and Future

Asthma has been recognised as a respiratory disorder for millennia and the focus of targeted drug development for the last 120 years. Asthma is one of the most common chronic non-communicable diseases worldwide. Chronic obstructive pulmonary disease (COPD), a leading cause of morbidity and mortality worldwide, is caused by exposure to tobacco smoke and other noxious particles and exerts a substantial economic and social burden. This chapter reviews the development of the treatments of asthma and COPD particularly focussing on the β-agonists, from the isolation of adrenaline, through the development of generations of short- and long-acting β-agonists. It reviews asthma death epidemics, considers the intrinsic efficacy of clinical compounds, and charts the improvement in selectivity and duration of action that has led to our current medications. Important β2-agonist compounds no longer used are considered, including some with additional properties, and how the different pharmacological properties of current β2-agonists underpin their different places in treatment guidelines. Finally, it concludes with a look forward to future developments that could improve the β-agonists still further, including extending their availability to areas of the world with less readily accessible healthcare.

Circular RNAs: emerging players in asthma and COPD

Circular RNAs (circRNAs) belong to a unique class of endogenously expressed non-protein-coding RNAs with a distinct circularized structure, characterized by the absence of 5'-cap and 3'-polyadenylate ends. They are generally formed through back-splicing from pre-mRNAs. They serve as regulators of transcription and splicing, and act as sponges for microRNAs (miRNAs) and RNA-binding proteins, thereby modulating the expression of target genes. As a result, they exert a substantial impact on a diverse array of cellular and biological processes, including cell proliferation, migration, inflammation, and oxidative stress. Asthma and COPD are chronic airway conditions that currently have no cure. In recent years, emerging evidence suggests that altered expression of circRNAs in airway, bronchial and immune cells is involved in asthma and COPD pathogenesis. Studies exploring circRNA dysregulation in asthma have showcased their involvement in regulating the proliferation, migration, and inflammation of airway smooth muscle and bronchial epithelial cells, as well as impacting goblet cell metaplasia, Th2 cell differentiation, and macrophage activation, primarily through interactions with miRNAs. Similarly, in COPD, circRNAs have shown altered expression patterns in the blood and lungs of patients, and these changes have been linked to modulating inflammation, oxidative stress, and airway remodeling in preclinical models. Furthermore, certain circRNAs have demonstrated promising potential as diagnostic and prognostic biomarkers for both asthma and COPD. This review delves into the current understanding of the function and molecular mechanisms of circRNAs in asthma and COPD, along with exploring their potential as biomarkers in these respiratory conditions.

Polymorphism in ADAM33 gene associated with asthmatics in West Bengal, India - An investigation by in-silico analysis

Introduction

Asthma is one of the common chronic polygenic inflammatory diseases. Genome wide association studies have identified ADAM33 as an asthma candidate gene. The present study investigated possible association of rs2280090 (T1), rs2280091 (T2) and rs3918396 (S1) single nucleotide polymorphisms (SNPs) of ADAM33 with aeroallergen induced asthma in West Bengal population, India. In addition, in-silico analysis was performed to find out changes in protein function.

Methods

Forced expiratory volume in 1 second (FEV1)/Forced vital capacity (FVC), peak expiratory flow rate (PEFR) were assessed using spirometry in 1039 participants. Allergic sensitivity of 619 spirometry positive asthma patients was assessed by skin prick test (SPT) against 22 aeroallergens. For genotyping of T1, T2, and S1 SNPs in 540 allergic asthma patient and 420 control subjects, polymerase chain reaction-based restriction fragment length polymorphism was performed. Total Immunoglobulin-E (IgE) level was measured in both patients and controls. ADAM333 haplotype blocks were constructed using Haploview software v.4.2. Structural model of transmembrane and cytoplasmic domains of ADAM33 was generated using RaptorX. Protein-protein interaction was analysed using the STRING server.

Results

Highest number of patient sensitivity was observed towards Cocos nusifera (n = 215) and Dermatophagoides farinae (n = 229). Significant difference in sensitivity was observed between child and late adult (P = 0.03), child and early adult (P = 0.02), adolescent and late adult (P = 0.02) and adolescent and early adult (P = 0.01). Genotypic frequencies differed significantly between patients and controls (P < 0.05). rs2280090 GG, rs2280091GG and AG genotype, and rs3918396 AA carried significant risk for asthma (P = 0.02, P = 0.008, P = 0.04, P = 0.01 respectively). ADAM33 T1, T2, and S1 polymorphisms were in high Linkage Disequilibrium (D = 0.98). Haplotype consisting of rs2280090G, rs2280091G and rs3918396A alleles were found significantly higher in patient population in comparison with controls (OR = 2.03). IgE level differed significantly among different genotypes for T1, T2, and S1 SNPs analysed in pair (P < 0.0001). FEV1/FVC ratio differed significantly among different genotypes for T1, T2 and S1 SNPs analysed in pair (P < 0.0001). Significant difference of FEV1/FVC was also found between GGA and AAG haplotype (P < 0.0001). In-silico analysis revealed T1 and T2 polymorphisms are located in cytoplasmic domain of ADAM33 may cause bronchial smooth muscle cell mobility and cellular hyperplasia as well as cytoskeletal remodelling by altered interaction with different cytoplasmic proteins found by string analysis.

Conclusion

Present study showed significant association of T1, T2, and S1 polymorphisms of ADAM33 with aeroallergen-induced asthma in West Bengal, India. These polymorphisms may be used as prognostic markers and possible targets for therapeutics in future.

Critical roles of airway smooth muscle in mediating deep-inspiration-induced bronchodilation: a big stretch?

BACKGROUND

Deep inspiration (DI) has been shown to induce bronchodilation and bronchoprotection in bronchochallenged healthy subjects, but not in asthmatics. Strain-induced relaxation of airway smooth muscle (ASM) is considered one of the factors responsible for these effects. Other factors include the release or redistribution of pulmonary surfactant, alteration in mucus plugs, and changes in airway heterogeneity.

MAIN BODY

The present review is focused on the DI effect on ASM function, based on recent findings from ex vivo sheep lung experiments showing a large change in airway diameter during a DI. The amount of stretch on the airways, when applied to isolated airway rings in vitro, caused a substantial decrease in ASM contractility that takes many minutes to recover. When challenged with a bronchoconstrictor, the increase in pulmonary resistance in the ex vivo ovine lungs is mostly due to the increase in airway resistance.

CONCLUSIONS

Although non-ASM related factors cannot be excluded, the large strain on the airways associated with a DI substantially reduces ASM contractility and thus can account for most of the bronchodilatory and bronchoprotective effects of DI.

Intrinsically bioactive and biomimetic nanoparticle-derived therapies alleviate asthma by regulating multiple pathological cells

Asthma is a serious global public health concern. Airway neutrophilic inflammation is closely related to severe asthma, for which effective and safe therapies remain to be developed. Here we report nanotherapies capable of simultaneously regulating multiple target cells relevant to the pathogenesis of neutrophilic asthma. A nanotherapy LaCD NP based on a cyclic oligosaccharide-derived bioactive material was engineered. LaCD NP effectively accumulated in the injured lungs of asthmatic mice and mainly distributed in neutrophils, macrophages, and airway epithelial cells after intravenous or inhalation delivery, thereby ameliorating asthmatic symptoms and attenuating pulmonary neutrophilic inflammation as well as reducing airway hyperresponsiveness, remodeling, and mucus production. Surface engineering via neutrophil cell membrane further enhanced targeting and therapeutic effects of LaCD NP. Mechanistically, LaCD NP can inhibit the recruitment and activation of neutrophils, especially reducing the neutrophil extracellular traps formation and NLRP3 inflammasome activation in neutrophils. Also, LaCD NP can suppress macrophage-mediated pro-inflammatory responses and prevent airway epithelial cell death and smooth muscle cell proliferation, by mitigating neutrophilic inflammation and its direct effects on relevant cells. Importantly, LaCD NP showed good safety performance. Consequently, LaCD-derived multi-bioactive nanotherapies are promising for effective treatment of neutrophilic asthma and other neutrophil-associated diseases.

Macrophage migration inhibitory factor exacerbates asthmatic airway remodeling via dynamin-related protein 1-mediated autophagy activation

BACKGROUND

Macrophage migration inhibitory factor (MIF) and GTPase dynamin-related protein 1 (Drp1)-dependent aberrant mitochondrial fission are closely linked to the pathogenesis of asthma. However, it is unclear whether Drp1-mediated mitochondrial fission and its downstream targets mediate MIF-induced proliferation of airway smooth muscle cells (ASMCs) in vitro and airway remodeling in chronic asthma models. The present study aims to clarify these issues.

METHODS

In this study, primary cultured ASMCs and ovalbumin (OVA)-induced asthmatic rats were applied. Cell proliferation was detected by CCK-8 and EdU assays. Western blotting was used to detect extracellular signal-regulated kinase (ERK) 1/2, Drp1, autophagy-related markers and E-cadherin protein phosphorylation and expression. Inflammatory cytokines production, airway reactivity test, histological staining and immunohistochemical staining were conducted to evaluate the development of asthma. Transmission electron microscopy was used to observe the mitochondrial ultrastructure.

RESULTS

In primary cultured ASMCs, MIF increased the phosphorylation level of Drp1 at the Ser616 site through activation of the ERK1/2 signaling pathway, which further activated autophagy and reduced E-cadherin expression, ultimately leading to ASMCs proliferation. In OVA-induced asthmatic rats, MIF inhibitor 4-iodo-6-phenylpyrimidine (4-IPP) treatment, suppression of mitochondrial fission by Mdivi-1 or inhibiting autophagy with chloroquine phosphate (CQ) all attenuated the development of airway remodeling.

CONCLUSIONS

The present study provides novel insights that MIF promotes airway remodeling in asthma by activating autophagy and degradation of E-cadherin via ERK/Drp1 signaling pathway, suggesting that targeting MIF/ERK/Drp1 might have potential therapeutic value for the prevention and treatment of asthma.

Epithelial-Mesenchymal Transition Mechanisms in Chronic Airway Diseases: A Common Process to Target?

Epithelial-to-mesenchymal transition (EMT) is a reversible process, in which epithelial cells lose their epithelial traits and acquire a mesenchymal phenotype. This transformation has been described in different lung diseases, such as lung cancer, interstitial lung diseases, asthma, chronic obstructive pulmonary disease and other muco-obstructive lung diseases, such as cystic fibrosis and non-cystic fibrosis bronchiectasis. The exaggerated chronic inflammation typical of these pulmonary diseases can induce molecular reprogramming with subsequent self-sustaining aberrant and excessive profibrotic tissue repair. Over time this process leads to structural changes with progressive organ dysfunction and lung function impairment. Although having common signalling pathways, specific triggers and regulation mechanisms might be present in each disease. This review aims to describe the various mechanisms associated with fibrotic changes and airway remodelling involved in chronic airway diseases. Having better knowledge of the mechanisms underlying the EMT process may help us to identify specific targets and thus lead to the development of novel therapeutic strategies to prevent or limit the onset of irreversible structural changes.

Design, Synthesis, and Biological Evaluation of Novel Spiro Imidazobenzodiazepines to Identify Improved Inhaled Bronchodilators

Novel gamma-aminobutyric acid receptor (GABAAR) ligands structurally related to imidazobenzodiazepine MIDD0301 were synthesized using spiro-amino acid N-carboxyanhydrides (NCAs). These compounds demonstrated increased resistance to phase 2 metabolism and avoided the formation of a 6H isomer. Compound design was guided by molecular docking using the available crystal structure of the α1β3γ2 GABAAR and correlated with in vitro binding data. The carboxylic acid containing GABAAR ligands have high aqueous solubility, low permeability, and low cell toxicity. The inability of GABAAR ligands to cross the blood-brain barrier was confirmed in vivo by the absence of sensorimotor inhibition. Pharmacological activities at lung GABAARs were demonstrated by ex vivo relaxation of guinea pig airway smooth muscle and reduction of methacholine-induced airway hyperresponsiveness (AHR) in conscious mice. We identified bronchodilator 5c with an affinity of 9 nM for GABAARs that was metabolically stable in the presence of human and mouse microsomes.

Functional α7 nicotinic receptors in human airway smooth muscle increase intracellular calcium concentration and contractility in asthmatics

Although nicotinic acetylcholine receptors (nAChRs) are commonly associated with neurons in the brain and periphery, recent data indicate that they are also expressed in non-neuronal tissues. We recently found the alpha7 (α7nAChR) subunit is highly expressed in human airway smooth muscle (hASM) with substantial increase in asthmatics, but their functionality remains unknown. We investigated the location and functional role of α7nAChRs in hASM cells from normal versus mild-moderate asthmatic patients. Immunostaining and protein analyses showed α7nAChR in the plasma membrane including in asthmatics. In asthmatic hASM, patch-clamp recordings revealed significantly higher functional homomeric α7nAChR channels. Real-time fluorescence imaging showed nicotine, via α7nAChR, increases intracellular Ca2+ ([Ca2+]i) independent of ACh effects, particularly in asthmatic hASM, while cellular traction force microscopy showed nicotine-induced contractility including in asthmatics. These results indicate functional homomeric and heteromeric nAChRs that are increased in asthmatic hASM, with pharmacology that likely differ owing to different subunit interfaces that form the orthosteric sites. nAChRs may represent a novel target in alleviating airway hyperresponsiveness in asthma.NEW & NOTEWORTHY Cigarette smoking and vaping exacerbate asthma. Understanding the mechanisms of nicotine effects in asthmatic airways is important. This study demonstrates that functional alpha7 nicotinic acetylcholine receptors (α7nAChRs) are expressed in human airway smooth muscle, including from asthmatics, and enhance intracellular calcium and contractility. Although a7nAChRs are associated with neuronal pathways, α7nAChR in smooth muscle suggests inhaled nicotine (e.g., vaping) can directly influence airway contractility. Targeting α7nAChR may represent a novel approach to alleviating airway hyperresponsiveness in asthma.

Noncoding RNAs in asthmatic airway smooth muscle cells

Asthma is a complex and heterogeneous airway disease caused by genetic, environmental and epigenetic factors treated with hormones and biologics. Irreversible pathological changes to airway smooth muscle cells (ASMCs) such as hyperplasia and hypertrophy can occur in asthmatic patients. Determining the mechanisms responsible is vital for preventing such changes. In recent years, noncoding RNAs (ncRNAs), especially microRNAs, long noncoding RNAs and circular RNAs, have been found to be associated with abnormalities of the ASMCs. This review highlights recent ncRNA research into ASMC pathologies. We present a schematic that illustrates the role of ncRNAs in pathophysiological changes to ASMCs that may be useful in future research in diagnostic and treatment strategies for patients with asthma.

Targeting calcium signaling by inositol trisphosphate receptors: A novel mechanism for the anti-asthmatic effects of Houttuynia cordata

Asthma is a chronic inflammatory disease characterized by airway hypersensitivity and remodeling. The current treatments provide only short-term benefits and may have undesirable side effects; thus, alternative or supplementary therapy is needed. Because intracellular calcium (Ca²⁺) signaling plays an essential role in regulating the contractility and remodeling of airway smooth muscle cells, the targeting of Ca²⁺ signaling is a potential therapeutic strategy for asthma. Houttuynia cordata is a traditional Chinese herb that is used to treat asthma due to its anti-allergic and anti-inflammatory properties. We hypothesized that H. cordata might modulate intracellular Ca²⁺ signaling and could help relieve asthmatic airway remodeling. We found that the mRNA and protein levels of inositol trisphosphate receptors (IP₃Rs) were elevated in interleukin-stimulated primary human bronchial smooth muscle cells and a house dust mite-sensitized model of asthma. The upregulation of IP₃R expression enhanced intracellular Ca²⁺ release upon stimulation and contributed to airway remodeling in asthma. Intriguingly, pretreatment with H. cordata essential oil rectified the disruption of Ca²⁺ signaling, mitigated asthma development, and prevented airway narrowing. Furthermore, our analysis suggested that houttuynin/2-undecanone could be the bioactive component in H. cordata essential oil because we found similar IP₃R suppression in response to the commercially available derivative sodium houttuyfonate. An in silico analysis showed that houttuynin, which downregulates IP₃R expression, binds to the IP₃ binding domain of IP₃R and may mediate a direct inhibitory effect. In summary, our findings suggest that H. cordata is a potential alternative treatment choice that may reduce asthma severity by targeting the dysregulation of Ca²⁺ signaling.

The Role of Vitamins in the Pathogenesis of Asthma

Vitamins play a crucial role in the proper functioning of organisms. Disturbances of their levels, seen as deficiency or excess, enhance the development of various diseases, including those of the cardiovascular, immune, or respiratory systems. The present paper aims to summarize the role of vitamins in one of the most common diseases of the respiratory system, asthma. This narrative review describes the influence of vitamins on asthma and its main symptoms such as bronchial hyperreactivity, airway inflammation, oxidative stress, and airway remodeling, as well as the correlation between vitamin intake and levels and the risk of asthma in both pre- and postnatal life.

LXA4 inhibits TGF-β1-induced airway smooth muscle cells proliferation and migration by suppressing the Smad/YAP pathway

The aims of the present study were to examine the signaling mechanisms for transforming growth factor-β1 (TGF-β1)-induced rat airway smooth muscle cells (ASMCs) proliferation and migration and to determine the effect of lipoxin A4 (LXA4) on TGF-β1-induced rat ASMCs proliferation and migration and its underlying mechanisms. TGF-β1 upregulated transcriptional coactivator Yes-associated protein (YAP) expression by activating Smad2/3 and then upregulated cyclin D1, leading to rat ASMCs proliferation and migration. This effect was reversed after treatment with the TGF-β1 receptor inhibitor SB431542. YAP is a critical mediator of TGF-β1-induced ASMCs proliferation and migration. Knockdown of YAP disrupted the pro-airway remodeling function of TGF-β1. Preincubation of rat ASMCs with LXA4 blocked TGF-β1-induced activation of Smad2/3 and changed its downstream targets, YAP and cyclin D1, resulting in the inhibition of rat ASMCs proliferation and migration. Our study suggests that LXA4 suppresses Smad/YAP signaling to inhibit rat ASMCs proliferation and migration and therefore has potential value in the prevention and treatment of asthma by negatively modulating airway remodeling.

Asthma

Asthma is one of the most common chronic non-communicable diseases worldwide and is characterised by variable airflow obstruction, causing dyspnoea and wheezing. Highly effective therapies are available; asthma morbidity and mortality have vastly improved in the past 15 years, and most patients can attain good asthma control. However, undertreatment is still common, and improving patient and health-care provider understanding of when and how to adjust treatment is crucial. Asthma management consists of a cycle of assessment of asthma control and risk factors and adjustment of medications accordingly. With the introduction of biological therapies, management of severe asthma has entered the precision medicine era-a shift that is driving clinical ambitions towards disease remission. Patients with severe asthma often have co-existing conditions contributing to their symptoms, mandating a multidimensional management approach. In this Seminar, we provide a clinically focused overview of asthma; epidemiology, pathophysiology, diagnosis, and management in children and adults.

Myocd regulates airway smooth muscle cell remodeling in response to chronic asthmatic injury

Abnormal growth of airway smooth muscle cells is one of the key features in asthmatic airway remodeling, which is associated with asthma severity. The mechanisms underlying inappropriate airway smooth muscle cell growth in asthma remain largely unknown. Myocd has been reported to act as a key transcriptional coactivator in promoting airway-specific smooth muscle development in fetal lungs. Whether Myocd controls airway smooth muscle remodeling in asthma has not been investigated. Mice with lung mesenchyme-specific deletion of Myocd after lung development were generated, and a chronic asthma model was established by sensitizing and challenging the mice with ovalbumin for a prolonged period. Comparison of the asthmatic pathology between the Myocd knockout mice and the wild-type controls revealed that abrogation of Myocd mitigated airway smooth muscle cell hypertrophy and hyperplasia, accompanied by reduced peri-airway inflammation, decreased fibrillar collagen deposition on airway walls, and attenuation of abnormal mucin production in airway epithelial cells. Our study indicates that Myocd is a key transcriptional coactivator involved in asthma airway remodeling. Inhibition of Myocd in asthmatic airways may be an effective approach to breaking the vicious cycle of asthmatic progression, providing a novel strategy in treating severe and persistent asthma. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Effect of icariin on the H2O2-induced proliferation of mouse airway smooth muscle cells through miR-138-5p regulating SIRT1/AMPK/PGC-1α axis

Icariin exerts antioxidative and anti-inflammatory effects and is used in the treatment of bronchial asthma. However, the specific modes of action are uncertain. In this study, we investigated whether icariin could modulate the silencing information regulator 2-related enzyme 1 (SIRT1)/adenosine monophosphate-activated protein kinase (AMPK)/peroxisome proliferator-activated receptor gamma co-activator 1α (PGC-1α) axis by regulating miR-138-5p during H₂O₂-induced proliferation of mouse airway smooth muscle cells (ASMCs). Primary BALB/c mouse ASMCs were cultured using the tissue block adherence method and were induced with hydrogen peroxide (H₂O₂; 200 μmol/L) to establish a bronchial asthma ASMC proliferation model. With the aid of Western Blot and quantitative real-time polymerase chain reaction (qRT-PCR) in H₂O₂-induced ASMCs, the expression of miR-138-5p, SIRT1, AMPK, PGC-1α, α-smooth muscle actin (α-SMA), transforming growth factor-β1 (TGF-β1), collagen I, and collagen III protein and mRNA were investigated. The proliferation rate and activities of superoxide dismutase1 (SOD1), reduced glutathione (GSH), malonaldehyde (MDA), and reactive oxygen species (ROS) in ASMCs were determined. The results suggest Compared with the H₂O₂-induced group, icariin inhibited the miR-138-5p expression; enhanced SIRT1, p-AMPK, and PGC-1α expression; attenuated MDA activity and ROS level; lowered TGF-β1, collagen I, and collagen III expression levels; and decreased the proliferation of ASMCs induced by H₂O₂. The dual-luciferase reporter gene assay results showed that SIRT1 is a regulatory target of miR-138-5p.The results suggest that Icariin could improve the H₂O₂-induced proliferation of ASMCs. The mechanism may be related to the increase of activation of SIRT1/AMPK/PGC-1α axis by suppressing the expression of miR-138-5p. Thus, SIRT1 is the regulatory target of miR-138-5p.

Increased serum cotinine and obesity negatively impact asthma exacerbations and hospitalizations: A cross-sectional analysis of NHANES

Background

Asthma is the most common non-communicable chronic airway disease worldwide. Obesity and cigarette use independently increase asthma morbidity and mortality. Current literature suggests that obesity and smoking synergistically increase asthma-related wheezing.

Objective

To assess whether increased serum cotinine and obesity act synergistically to increase the likelihood of having an asthma exacerbation, emergency department (ED) visit, or hospitalization.

Methods

A cross-sectional analysis of the 2011-2015 iterations of NHANES database was performed. Patients aged 18 years or greater with asthma were included. Serum cotinine was utilized as an accurate measurement of cigarette use. Logistic regression models were constructed to determine whether elevated serum cotinine and obesity were associated with self-reported asthma exacerbations, asthma-specific ED usage, and hospitalizations for any reason in the past year. Odds ratios were adjusted for age, gender, race, and ethnicity. Interactions were assessed by multiplying the adjusted effect sizes for elevated cotinine and obesity.

Results

We identified 2179 (N = 32,839,290) patients with asthma, of which 32.2% were active smokers and 42.7% were obese. Patients with an elevated cotinine and asthma were significantly more likely to have had an asthma-related ED visit in the past year (adjusted odds ratio [AOR] 1.82; 95% CI 1.19-2.79), have a physician-prescribed asthma medication (AOR 2.04; 95% CI 1.11-3.74), and have a hospitalization for any reason (AOR 3.65; 95% CI 1.88-7.07) compared to those with low cotinine. Patients with asthma and obesity were more likely to have an asthma-related ED visit (AOR 1.67; 95% CI 1.06-2.62) or hospitalization for any reason in the past year compared to non-obese patients (AOR 2.76; 95% CI 1.69-4.5). However, a statistically significant interaction between obesity and cotinine was only identified in patients who currently have asthma compared to a previous asthma diagnosis (AOR 1.76; 95% CI 1.10-2.82). There were no synergistic interactions among ED usage or asthma exacerbations.

Conclusion

Nearly one-third of patients with asthma were current smokers, and almost half were obese. This study identified elevated serum cotinine, a metabolite of cigarette use, and obesity as key risk factors for asthma exacerbations, asthma-related ED visits, and hospitalizations for any reason. Elevated serum cotinine and obesity were not found to act synergistically in increasing asthma exacerbations or ED visits. However, the presence of both risk factors increased the risk of currently having asthma (compared to a previous diagnosis) by 76%. Serum cotinine may be useful in predicting asthma outcomes.

β-sitosterol targets glucocorticoid receptor to reduce airway inflammation and remodeling in allergic asthma

INTRODUCTION

In most asthma patients, symptoms are controlled by treatment with glucocorticoid, but long-term or high-dose use can produce adverse effects. Therefore, it is crucial to find new therapeutic strategies. β-sitosterol could suppress type Ⅱ inflammation in ovalbumin (OVA)-induced mice, but its mechanisms have remained unclear.

METHODS

A binding activity of β-sitosterol with glucocorticoid receptor (GR) was analyzed by molecular docking. Human bronchial epithelial cells (BEAS-2B) and human bronchial smooth muscle cells (HBSMC) were treated with different concentrations (0, 1, 5, 10, 20, and 50 μg/mL) of β-sitosterol for suitable concentration selection. In transforming growth factor (TGF)-β1 treated BEAS-2B and HBSMC, cells were treated with 20 μg/mL β-sitosterol or dexamethasone (Dex) to analyze its possible mechanism. In OVA-induced mice, 2.5 mg/kg β-sitosterol or Dex administration was performed to analyze the therapeutic mechanism of β-sitosterol. A GR antagonist RU486 was used to confirm the mechanism of β-sitosterol in the treatment of asthma.

RESULTS

A good binding of β-sitosterol to GR (score = -8.2 kcal/mol) was found, and the GR expression was upregulated with β-sitosterol dose increase in BEAS-2B and HBSMC. Interleukin (IL)-25 and IL-33 secretion was significantly decreased by β-sitosterol in the TGF-β1-induced BEAS-2B, and the levels of collagen 1A and α-smooth muscle actin (SMA) were reduced in the TGF-β1-induced HBSMC. In the OVA-challenged mice, β-sitosterol treatment improved airway inflammation and remodeling through suppressing type Ⅱ immune response and collagen deposition. The therapeutic effects of β-sitosterol were similar to Dex treatment in vitro and in vivo. RU486 treatment clearly hampered the therapeutic effects of β-sitosterol in the TGF-β1-induced cells and OVA-induced mice.

CONCLUSION

This study identified that β-sitosterol binds GR to perform its functions in asthma treatment. β-sitosterol represent a potential therapeutic drug for allergic asthma.