Airway remodelling in asthma: from benchside to clinical practice

Role of impulse oscillometry in diagnosis and follow-up in bronchial asthma

Background

Asthma is defined as a chronic inflammatory disorder of the airways, characterized by bronchial hyper-responsiveness and variable airflow obstruction, that is often reversible either spontaneously or with treatment. Impulse oscillometry is a newer diagnostic modality for asthma. It is based on the measurement of sound waves reflected by airway resistance.

Objectives

The aim of this article is to study the role of impulse oscillometry in diagnosis and follow-up of bronchial asthma.

Methods

Fifty-five clinically diagnosed bronchial asthma patients were evaluated with spirometry and impulse oscillometry before and after 3 months of inhaled treatment. The sensitivity to diagnose and follow-up was compared using proper statistical tests.

Results

Impulse oscillometry was superior to spirometry in diagnosing bronchial asthma and also in accessing the treatment response after 3 months.

Conclusion

Impulse oscillometry is superior in predicting bronchial asthma and its parameters are also more sensitive in accessing treatment response. It can replace spirometry as it is easy to perform and effort independent.

Consensus on mild asthma management: results of a modified Delphi study

OBJECTIVE

In order to understand the role of regular controller inhaled corticosteroids (ICS) versus as-needed ICS-formoterol in managing mild asthma, we performed a modified Delphi procedure.

METHODS

Opinions from 16 respiratory experts to three surveys and during a virtual scientific workshop helped to develop final consensus statements (pre-defined as 70% agreement).

RESULTS

Thirteen participants completed all rounds (response rate 81%). At the end of the procedure, there was final consensus on: regular daily ICS being the recommended treatment approach in mild persistent asthma, with better symptom control and robust long-term clinical data compared with as-needed ICS-formoterol (85%); to avoid noncompliance, frequently seen in mild asthma patients, regular ICS dosing should be accompanied by ongoing education on treatment adherence (100%); treatment aims should be targeting asthma control (92%) and reduction of exacerbation risk (85%). No consensus was reached on whether GINA or national guidelines most influence prescribing decisions.

CONCLUSIONS

It is important to encourage patients to be adherent and to target both asthma control and exacerbation risk reduction. There is robust clinical evidence to support proactive regular dosing with ICS controller therapy plus as-needed short-acting beta-agonists for the management of patients with mild asthma.

ABBREVIATIONS.

Supplemental data for this article is available online at https://doi.org/10.1080/02770903.2022.2034850 .

Expression of MUC-2, MUC-6, NAPE-PLD, IL-6 and IL-13 in Healthy and Metaplastic Bronchial Epithelium

Background: The normal tissue structure of the respiratory system is necessary to provide adequate protection of the airways and lungs. Prolonged exposure to trigger factors can result in adaptive mechanism activation and lead to the development of chronic pulmonary diseases or even dysplastic changes. Materials and methods: Respiratory system material with a pseudostratified ciliated epithelium was obtained from 12 patients (aged 16 to 95), and material with a stratified squamosa epithelium was obtained from six patients (aged 23 to 93). Routine staining was performed, and an immunohistochemistry was conducted for MUC-2, MUC-6, NAPE-PLD, IL-6 and IL-13. Results: Inflammatory processes were not detected in any of the specimens. A number of correlations were identified, with the most important being a strong positive correlation for IL-13 between the alveolar epithelium and alveolar macrophages and a strong positive correlation for IL-6 between the alveolar epithelium and alveolar macrophages in the stratified squamous epithelium group. We also detected a statistically significant difference in IL-6 in alveolar macrophages. Conclusions: There were no signs of dysplastic changes in either group. Increased secretion of IL-13 in the stratified squamous epithelium group shows its involvement in metaplastic changes in the bronchial epithelium. The secretion of atypical factors by hyaline cartilage demonstrates its plasticity and adaptability.

Cellular senescence is increased in airway smooth muscle cells of elderly persons with asthma

Senescent cells can drive age-related tissue dysfunction partially via a senescence-associated secretory phenotype (SASP) involving proinflammatory and profibrotic factors. Cellular senescence has been associated with a structural and functional decline during normal lung aging and age-related diseases such as chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF). Asthma in the elderly (AIE) represents a major healthcare burden. AIE is associated with bronchial airway hyperresponsiveness and remodeling, which involves increased cell proliferation and higher rates of fibrosis, and resistant to standard therapy. Airway smooth muscle (ASM) cells play a major role in asthma such as remodeling via modulation of inflammation and the extracellular matrix (ECM) environment. Whether senescent ASM cells accumulate in AIE and contribute to airway structural or functional changes is unknown. Lung tissues from elderly persons with asthma showed greater airway fibrosis compared with age-matched elderly persons with nonasthma and young age controls. Lung tissue or isolated ASM cells from elderly persons with asthma showed increased expression of multiple senescent markers including phospho-p53, p21, telomere-associated foci (TAF), as well as multiple SASP components. Senescence and SASP components were also increased with aging per se. These data highlight the presence of cellular senescence in AIE that may contribute to airway remodeling.

Role of airway epithelial cell miRNAs in asthma

The airway epithelial cells and overlying layer of mucus are the first point of contact for particles entering the lung. The severity of environmental contributions to pulmonary disease initiation, progression, and exacerbation is largely determined by engagement with the airway epithelium. Despite the cellular cross-talk and cargo exchange in the microenvironment, epithelial cells produce miRNAs associated with the regulation of airway features in asthma. In line with this, there is evidence indicating miRNA alterations related to their multifunctional regulation of asthma features in the conducting airways. In this review, we discuss the cellular components and functions of the airway epithelium in asthma, miRNAs derived from epithelial cells in disease pathogenesis, and the cellular exchange of miRNA-bearing cargo in the airways.

Elevated serum periostin levels among arsenic-exposed individuals and their associations with the features of asthma

Chronic exposure to arsenic via drinking water is a serious public health issue in many countries. Arsenic causes not only cancers but also non-malignant diseases, including asthma. We have previously reported that arsenic exposure increases the risk of Th2-mediated allergic asthma. The serum level of periostin, an extracellular matrix protein activated by Th2 cytokines, is recognized as a biomarker for Th2-mediated eosinophilic asthma and contributes to enhanced airway inflammation and remodeling. However, the role of periostin in arsenic-related asthma is unknown. Therefore, this study was designed to explore the associations of serum periostin levels with arsenic exposure and the features of asthma in 442 individuals in Bangladesh who participated in our previous study. Exposure levels of the participants were determined by measuring the arsenic concentrations in drinking water, hair, and nails through inductively coupled plasma mass spectroscopy. Periostin levels in serum were assessed by immunoassay. In this study, we found that serum periostin levels of the participants were increased with increasing exposure to arsenic. Notably, even the participants with 10.1-50 μg/L arsenic in drinking water had significantly higher levels of periostin than participants with <10 μg/L of water arsenic. Elevated serum periostin levels were positively associated with serum levels of Th2 mediators, such as interleukin (IL)-4, IL-5, IL-13, and eotaxin. Each log increase in periostin levels was associated with approximately eight- and three-fold increases in the odds ratios (ORs) for reversible airway obstruction (RAO) and asthma symptoms, respectively. Additionally, causal mediation analyses revealed that arsenic exposure metrics had both direct and indirect (periostin-mediated) effects on the risk of RAO and asthma symptoms. Thus, the results suggested that periostin may be involved in the arsenic-related pathogenesis of Th2-mediated asthma. The elevated serum periostin levels may predict the greater risk of asthma among the people living in arsenic-endemic areas.

Regulatory T Cells, a Viable Target Against Airway Allergic Inflammatory Responses in Asthma

Asthma is a multifactorial disorder characterized by the airway chronic inflammation, hyper-responsiveness (AHR), remodeling, and reversible obstruction. Although asthma is known as a heterogeneous group of diseases with various clinical manifestations, recent studies suggest that more than half of the clinical cases are ‘‘T helper type 2 (Th2)-high’’ type, whose pathogenesis is driven by Th2 responses to an inhaled allergen from the environmental exposures. The intensity and duration of inflammatory responses to inhaled allergens largely depend on the balance between effector and regulatory cells, but many questions regarding the mechanisms by which the relative magnitudes of these opposing forces are remained unanswered. Regulatory T cells (Tregs), which comprise diverse subtypes with suppressive function, have long been attracted extensive attention owing to their capability to limit the development and progression of allergic diseases. In this review we seek to update the recent advances that support an essential role for Tregs in the induction of allergen tolerance and attenuation of asthma progression once allergic airway inflammation established. We also discuss the current concepts about Treg induction and Treg-expressed mediators relevant to controlling asthma, and the therapies designed based on these novel insights against asthma in clinical settings.

Airway fibrin formation cascade in allergic asthma exacerbation: implications for inflammation and remodeling

BACKGROUND

Airway remodeling in patients with asthma, which leads to a decline in pulmonary function, is likely the result of repeated exacerbations often provoked by aeroallergen exposures. Aeroallegen exposure triggers a stereotypic response orchestrated by growth factor cytokines and other protein mediators. This results in a late-phase allergic reaction characterized by vascular permeability, recruitment of activated leukocytes, and activation of structural cells of the airway. The spectrum of protein mediators and their functions are incompletely understood.

METHODS

Bronchoalveolar lavage fluid (BALF) samples were obtained from 12 volunteers who exhibited robust eosinophilic recruitment following segmental bronchial provocation with allergen (SBP-Ag). We systematically identified and quantified proteins in BALF using high-performance liquid chromatography-high-resolution mass spectrometry (LC-MS/MS) followed by pathway analysis and correlations with airway physiology.

RESULTS

Pairwise analysis of protein abundance in BALF pre- vs post-SBP-Ag revealed that 55 proteins were upregulated and 103 proteins were downregulated. We observed enrichment of groups of proteins mapping to hemostasis/fibrin clot, platelet activation, lipoprotein assembly, neutrophil degranulation proteins, and acute-phase inflammation-airway remodeling pathways. The abundances of F2 and Fibrinogen γ (FGG) correlated with eosinophil numbers, whereas SERPINA3 negatively correlated with change in FeNO. The coagulation proteins F2 and KNG negatively correlated with FN1 an index of airway remodeling. Interestingly, patients with lower FEV1 showed distinct allergen-induced patterns of 8 BALF proteins, including MUC1, alarmins (HSPB1), and actin polymerization factors.

CONCLUSIONS

Protein abundance of the fibrin formation cascade, platelet activation and remodeling are associated with late-phase leukocyte numbers and markers of remodeling. Patients with lower FEV1 have distinct dynamic responses to allergen.

Novel potential treatable traits in asthma: Where is the research taking us?

Asthma is a complex, heterogeneous disease in which the underlying mechanisms are not fully understood. Patients are often grouped into phenotypes (based on clinical, biologic, and physiologic characteristics) and endotypes (based on distinct genetic or molecular mechanisms). Recently, patients with asthma have been broadly split into 2 phenotypes based on their levels of type 2 inflammation: type 2 and non-type 2 asthma. However, this approach is likely oversimplified, and our understanding of the non-type 2 mechanisms in asthma remains extremely limited. A better understanding of asthma phenotypes and endotypes may assist in development of drugs for new therapeutic targets in asthma. One approach is to identify "treatable traits," which are specific patient characteristics related to phenotypes and endotypes that can be targeted by therapies. This review will focus on emerging treatable traits in asthma and aim to describe novel patient subgroups and endotypes that may represent the next step in the search for new therapeutic approaches.

A serological biomarker of type I collagen degradation is related to a more severe, high neutrophilic, obese asthma subtype

Background

Asthma is a heterogeneous disease; therefore, biomarkers that can assist in the identification of subtypes and direct therapy are highly desirable. Asthma is a chronic inflammatory disease that leads to changes in the extracellular matrix (ECM) by matrix metalloproteinases (MMPs) degradation causing fragments of type I collagen that is released into circulation.

Objective

Here, we asked if MMP-generated type I collagen (C1M) was associated with subtypes of asthma.

Methods

C1M was serologically assessed at baseline in the adult participants of the All Age Asthma study (ALLIANCE) (n = 233), and in The Prospective Epidemiological Risk Factor study (PERF) (n = 283). In addition, C1M was assessed in mice sensitized to ovalbumin (OVA) and challenged with OVA aerosol. C1M was evaluated in mice with and without acute neutrophilic inflammation provoked by poly(cytidylic-inosinic) acid and mice treated with CP17, a peptide inhibiting neutrophil accumulation.

Results

Serum C1M was significantly increased in asthmatics compared to healthy controls (p = 0.0005). We found the increased C1M levels in asthmatics were related to blood neutrophil and body mass index (BMI) in the ALLIANCE cohort, which was validated in the PERF cohort. When patients were stratified into obese (BMI > 30) asthmatics with high neutrophil levels and uncontrolled asthma, this group had a significant increase in C1M compared to normal-weight (BMI < 25) asthmatics with low neutrophil levels and controlled asthma (p = 0.0277). C1M was significantly elevated in OVA mice with acute neutrophilic inflammation compared to controls (P = 0.0002) and decreased in mice treated with an inhibitor of neutrophil infiltration (p = 0.047).

Conclusion & clinical relevance

C1M holds the potential to identify a subtype of asthma that relates to severity, obesity, and high neutrophils. These data suggest that C1M is linked to a subtype of overall inflammation, not only derived from the lung. The link between C1M and neutrophils were further validated in in vivo model.

Trial registration

(ALLIANCE, NCT02419274).

Supplementary information

The online version contains supplementary material available at 10.1186/s40733-022-00084-6.

Translational Analysis of Moderate to Severe Asthma GWAS Signals Into Candidate Causal Genes and Their Functional, Tissue-Dependent and Disease-Related Associations

Asthma affects more than 300 million people globally and is both under diagnosed and under treated. The most recent and largest genome-wide association study investigating moderate to severe asthma to date was carried out in 2019 and identified 25 independent signals. However, as new and in-depth downstream databases become available, the translational analysis of these signals into target genes and pathways is timely. In this study, unique (U-BIOPRED) and publicly available datasets (HaploReg, Open Target Genetics and GTEx) were investigated for the 25 GWAS signals to identify 37 candidate causal genes. Additional traits associated with these signals were identified through PheWAS using the UK Biobank resource, with asthma and eosinophilic traits amongst the strongest associated. Gene expression omnibus dataset examination identified 13 candidate genes with altered expression profiles in the airways and blood of asthmatic subjects, including MUC5AC and STAT6. Gene expression analysis through publicly available datasets highlighted lung tissue cell specific expression, with both MUC5AC and SLC22A4 genes showing enriched expression in ciliated cells. Gene enrichment pathway and interaction analysis highlighted the dominance of the HLA-DQA1/A2/B1/B2 gene cluster across many immunological diseases including asthma, type I diabetes, and rheumatoid arthritis. Interaction and prediction analyses found IL33 and IL18R1 to be key co-localization partners for other genes, predicted that CD274 forms co-expression relationships with 13 other genes, including the HLA-DQA1/A2/B1/B2 gene cluster and that MUC5AC and IL37 are co-expressed. Drug interaction analysis revealed that 11 of the candidate genes have an interaction with available therapeutics. This study provides significant insight into these GWAS signals in the context of cell expression, function, and disease relationship with the view of informing future research and drug development efforts for moderate-severe asthma.

Epithelial 3D-spheroids as a tool to study air pollutant-induced lung pathology

Cigarette smoke (CS) and air pollutants (AP) activate pathological processes in bronchial epithelial cells resulting in lung function decline which severely impacts human health. Knowledge about the molecular mechanism(s) by which CS and AP induce pathology is limited. Our previous studies in 2D cultures of human bronchial epithelial (BEAS-2B) cells showed that CS exposure activates transforming growth factor-β1 (TGF-β1) release and signaling. Furthermore, CS exposure reduced the expression of E-cadherin, which was prevented by applying a TGF-β1 neutralizing antibody. Exposure of BEAS-2B cells cultured in 2D to diesel exhaust particles (DEP) increased TGF-β1 protein expression and reduced the expression of epithelial cell markers, whereas mesenchymal markers are upregulated. Conventional 2D cell culture may, however, not fully reflect the physiology of bronchial epithelial cells in vivo. To simulate the in vivo situation more closely we cultured the bronchial epithelial cells in a 3D environment in the current study. Treatment of epithelial spheroids with TGF-β resulted in reduced E-cadherin and increased collagen I expression, indicating the activation of epithelial-to-mesenchymal transition (EMT). Similarly, exposure of spheroids to DEP induced and EMT-like phenotype. Collectively, our data indicate AP induces an EMT-like phenotype of BEAS-2B cells in 3D spheroid cultures. This opens new avenues for drug development for the treatment of lung diseases induced by AP. The 3D spheroid cell culture is a novel, innovative and physiologically relevant model for culturing a variety of cells. It is a versatile tool for both high-throughput studies and for identifying molecular mechanisms involved in bronchial epithelial cell (patho)physiology.

Holy Grail: the journey towards disease modification in asthma

At present, there is no cure for asthma, and treatment typically involves therapies that prevent or reduce asthma symptoms, without modifying the underlying disease. A “disease-modifying” treatment can be classed as able to address the pathogenesis of a disease, preventing progression or leading to a long-term reduction in symptoms. Such therapies have been investigated and approved in other indications, e.g. rheumatoid arthritis and immunoglobulin E-mediated allergic disease. Asthma's heterogeneous nature has made the discovery of similar therapies in asthma more difficult, although novel therapies (e.g. biologics) may have the potential to exhibit disease-modifying properties. To investigate the disease-modifying potential of a treatment, study design considerations can be made, including: appropriate end-point selection, length of trial, age of study population (key differences between adults/children in physiology, pathology and drug metabolism) and comorbidities in the patient population. Potential future focus areas for disease-modifying treatments in asthma include early assessments (e.g. to detect patterns of remodelling) and interventions for patients genetically susceptible to asthma, interventions to prevent virally induced asthma and therapies to promote a healthy microbiome. This review explores the pathophysiology of asthma, the disease-modifying potential of current asthma therapies and the direction future research may take to achieve full disease remission or prevention.

Asthma is a complex, heterogeneous disease, which currently has no cure; this review explores the disease-modifying potential of asthma therapies and the direction future research may take to achieve disease remission or prevention.https://bit.ly/31AxYou

Plasma proteome changes linked to late phase response after inhaled allergen challenge in asthmatics

BACKGROUND

A subset of individuals with allergic asthma develops a late phase response (LPR) to inhaled allergens, which is characterized by a prolonged airway obstruction, airway inflammation and airway hyperresponsiveness. The aim of this study was to identify changes in the plasma proteome and circulating hematopoietic progenitor cells associated with the LPR following inhaled allergen challenge.

METHODS

Serial plasma samples from asthmatics undergoing inhaled allergen challenge were analyzed by mass spectrometry and immunosorbent assays. Peripheral blood mononuclear cells were analyzed by flow cytometry. Mass spectrometry data were analyzed using a linear regression to model the relationship between airway obstruction during the LPR and plasma proteome changes. Data from immunosorbent assays were analyzed using linear mixed models.

RESULTS

Out of 396 proteins quantified in plasma, 150 showed a statistically significant change 23 h post allergen challenge. Among the most upregulated proteins were three protease inhibitors: alpha-1-antitrypsin, alpha-1-antichymotrypsin and plasma serine protease inhibitor. Altered levels of 13 proteins were associated with the LPR, including increased factor XIII A and decreased von Willebrand factor. No relationship was found between the LPR and changes in the proportions of classical, intermediate, and non-classical monocytes.

CONCLUSIONS

Allergic reactions to inhaled allergens in asthmatic subjects were associated with changes in a large proportion of the measured plasma proteome, whereof protease inhibitors showed the largest changes, likely to influence the inflammatory response. Many of the proteins altered in relation to the LPR are associated with coagulation, highlighting potential mechanistic targets for future treatments of type-2 asthma.

Exploring the Potential Effects and Mechanisms of Asarum sieboldii Radix Essential Oil for Treatment of Asthma

Asthma, a common chronic pulmonary disorder characterized by airway remodeling, hyperresponsiveness and obstruction, can be aggravated by repeated exposure to particulate matter (PM). The potential effect and mechanisms of Asarum sieboldii Radix essential oil (AEO) against asthma were explored based on network pharmacology. AEO was pre-treated using a nebulizer for 3 weeks and the mice were sensitized to ovalbumin (OVA) and PM10 with the co-treatment of AEO for 4 weeks. In addition, A549 lung epithelial cells were sensitized with PM10 to investigate the underlying mechanisms of AEO regarding the lung-fibrosis-related mediators. The target genes of methyl eugenol, a main compound of AEO, were highly matched by 48% with the gene set of asthma. AEO markedly inhibited the increase in epithelial thickness through the accumulation of goblet cells in the airways. Collagen deposition in the lung tissues of OVA+PM10-challenged asthmatic mice was significantly decreased by AEO. AEO also inhibited the influx of inflammatory cells in the bronchoalveolar lavage fluid, as well as the increases in serum IgE and IgG2a and cytokines in the lung tissues. Furthermore, AEO regulated the expressions of fibrotic mediators, especially POSTN and TGF-β. In conclusion, we expect that AEO can be one of the effective alternative therapeutics to relieve asthma.

The Ability of Resveratrol to Attenuate Ovalbumin-Mediated Allergic Asthma Is Associated With Changes in Microbiota Involving the Gut-Lung Axis, Enhanced Barrier Function and Decreased Inflammation in the Lungs

Asthma is a chronic respiratory disease highly prevalent worldwide. Recent studies have suggested a role for microbiome-associated gut-lung axis in asthma development. In the current study, we investigated if Resveratrol (RES), a plant-based polyphenol, can attenuate ovalbumin (OVA)-induced murine allergic asthma, and if so, the role of microbiome in the gut-lung axis in this process. We found that RES attenuated allergic asthma with significant improvements in pulmonary functions in OVA-exposed mice when tested using plethysmography for frequency (F), mean volume (MV), specific airway resistance (sRaw), and delay time(dT). RES treatment also suppressed inflammatory cytokines in the lungs. RES modulated lung microbiota and caused an abundance of Akkermansia muciniphila accompanied by a reduction of LPS biosynthesis in OVA-treated mice. Furthermore, RES also altered gut microbiota and induced enrichment of Bacteroides acidifaciens significantly in the colon accompanied by an increase in butyric acid concentration in the colonic contents from OVA-treated mice. Additionally, RES caused significant increases in tight junction proteins and decreased mucin (Muc5ac) in the pulmonary epithelium of OVA-treated mice. Our results demonstrated that RES may attenuate asthma by inducing beneficial microbiota in the gut-lung axis and through the promotion of normal barrier functions of the lung.

Role of Th17 Cytokines in Airway Remodeling in Asthma and Therapy Perspectives

Airway remodeling is a frequent pathological feature of severe asthma leading to permanent airway obstruction in up to 50% of cases and to respiratory disability. Although structural changes related to airway remodeling are well-characterized, immunological processes triggering and maintaining this phenomenon are still poorly understood. As a consequence, no biotherapy targeting cytokines are currently efficient to treat airway remodeling and only bronchial thermoplasty may have an effect on bronchial nerves and smooth muscles with uncertain clinical relevance. Th17 cytokines, including interleukin (IL)-17 and IL-22, play a role in neutrophilic inflammation in severe asthma and may be involved in airway remodeling. Indeed, IL-17 is increased in sputum from severe asthmatic patients, induces the expression of "profibrotic" cytokines by epithelial, endothelial cells and fibroblasts, and provokes human airway smooth muscle cell migration in in vitro studies. IL-22 is also increased in asthmatic samples, promotes myofibroblast differentiation, epithelial-mesenchymal transition and proliferation and migration of smooth muscle cells in vitro. Accordingly, we also found high levels of IL-17 and IL-22 in a mouse model of dog-allergen induced asthma characterized by a strong airway remodeling. Clinical trials found no effect of therapy targeting IL-17 in an unselected population of asthmatic patients but showed a potential benefit in a sub-population of patients exhibiting a high level of airway reversibility, suggesting a potential role on airway remodeling. Anti-IL-22 therapies have not been evaluated in asthma yet but were demonstrated efficient in severe atopic dermatitis including an effect on skin remodeling. In this review, we will address the role of Th17 cytokines in airway remodeling through data from in vitro, in vivo and translational studies, and examine the potential place of Th17-targeting therapies in the treatment of asthma with airway remodeling.

Novel regulators of airway epithelial barrier function during inflammation: potential targets for drug repurposing

INTRODUCTION

Endogenous inflammatory signaling molecules resulting from deregulated immune responses, can impair airway epithelial barrier function and predispose individuals with airway inflammatory diseases to exacerbations and lung infections. Targeting the specific endogenous factors disrupting the airway barrier therefore has the potential to prevent disease exacerbations without affecting the protective immune responses.

AREAS COVERED

Here, we review the endogenous factors and specific mechanisms disrupting airway epithelial barrier during inflammation and reflect on whether these factors can be specifically targeted by repurposed existing drugs. Literature search was conducted using PubMed, drug database of US FDA and European Medicines Agency until and including September 2021.

EXPERT OPINION

IL-4 and IL-13 signaling are the major pathways disrupting the airway epithelial barrier during airway inflammation. However, blocking IL-4/IL-13 signaling may adversely affect protective immune responses and increase susceptibility of host to infections. An alternate approach to modulate airway epithelial barrier function involves targeting specific downstream component of IL-4/IL-13 signaling or different inflammatory mediators responsible for regulation of airway epithelial barrier. Airway epithelium-targeted therapy using inhibitors of HDAC, HSP90, MIF, mTOR, IL-17A and VEGF may be a potential strategy to prevent airway epithelial barrier dysfunction in airway inflammatory diseases.

Role of Secretoglobin+ (club cell) NFκB/RelA-TGFβ signaling in aero-allergen-induced epithelial plasticity and subepithelial myofibroblast transdifferentiation

Repetitive aeroallergen exposure is linked to sensitization and airway remodeling through incompletely understood mechanisms. In this study, we examine the dynamic mucosal response to cat dander extract (CDE), a ubiquitous aero-allergen linked to remodeling, sensitization and asthma. We find that daily exposure of CDE in naïve C57BL/6 mice activates innate neutrophilic inflammation followed by transition to a lymphocytic response associated with waves of mucosal transforming growth factor (TGF) isoform expression. In parallel, enhanced bronchiolar Smad3 expression and accumulation of phospho-SMAD3 was observed, indicating paracrine activation of canonical TGFβR signaling. CDE exposure similarly triggered epithelial cell plasticity, associated with expression of mesenchymal regulatory factors (Snai1 and Zeb1), reduction of epithelial markers (Cdh1) and activation of the NFκB/RelA transcriptional activator. To determine whether NFκB functionally mediates CDE-induced growth factor response, mice were stimulated with CDE in the absence or presence of a selective IKK inhibitor. IKK inhibition substantially reduced the level of CDE-induced TGFβ1 expression, pSMAD3 accumulation, Snai1 and Zeb1 expression. Activation of epithelial plasticity was demonstrated by flow cytometry in whole lung homogenates, where CDE induces accumulation of SMA⁺Epcam⁺ population. Club cells are important sources of cytokine and growth factor production. To determine whether Club cell innate signaling through NFκB/RelA mediated CDE induced TGFβ signaling, we depleted RelA in Secretoglobin (Scgb1a1)-expressing bronchiolar cells. Immunofluorescence-optical clearing light sheet microscopy showed a punctate distribution of Scgb1a1 progenitors throughout the small airway. We found that RelA depletion in Secretoglobin⁺ cells results in inhibition of the mucosal TGFβ response, blockade of EMT and reduced subepithelial myofibroblast expansion. We conclude that the Secretoglobin—derived bronchiolar cell is central to coordinating the innate response required for mucosal TGFβ1 response, EMT and myofibroblast expansion. These data have important mechanistic implications for how aero-allergens trigger mucosal injury response and remodeling in the small airway.

LncRNA RP5-857K21.7 inhibits PDGF-BB-induced proliferation and migration of airway smooth muscle cells through the miR-508-3p/PI3K/AKT/mTOR axis

The continuous increase in the prevalence of asthma poses a threat to human health. Despites numerous researches, the understanding of asthma development still remain elusive, hindering the development of effective treatment. Here, we explored the role of lncRNA RP5-857K21.7 (RP5-857K21.7) in the development of asthma and its potential molecular mechanism of regulation. Airway smooth muscle cells (ASMCs) were isolated and cultured after which some of the cells were induced with PDGF-BB to build an asthma cell model, and then, qRT-PCR analysis was used to measure the expression level of RP5-857K21.7 in the cell model. Result shows that the RP5-857K21.7 is significantly downregulated in PDGF-BB-induced ASMCs cells. Through CCK-8, transwell, and flow cytometry assay, we examined the functional impact of RP5-857K21.7 on the proliferation, migration, and apoptosis of the ASMCs, respectively, and found that the overexpression of RP5-857K21.7 markedly inhibit PDGF-BB-induced ASMCs cell proliferation, migration and induce apoptosis. Bioinformatics analysis predicted that the RP5-857K21.7 could sponge miR-508-3p and result was validated through a dual-luciferase reporter assay, biotinylated RNA pull-down assay, and RIP-qRT-PCR analysis. Mechanistically, RP5-857K21.7 regulates the PI3K/AKT/mTOR pathway by endogenously sponging miR-508-3p to inhibit PDGF-BB-induced ASMCs cell proliferation, migration and induce apoptosis. The current research suggests that the RP5-857K21.7 and its associated molecular pathway (miR-508-3p/PI3K/AKT/mTOR axis) might be a useful therapeutic target for the treatment of asthma disease.

Evodiamine protects against airway remodelling and inflammation in asthmatic rats by modulating the HMGB1/NF-κB/TLR-4 signalling pathway

CONTEXT

Evodiamine, which is isolated from Evodia rutaecarpa (Rutaceae), possess strong anti-inflammatory, immunomodulatory, and antibacterial properties.

OBJECTIVE

The protective effects of evodiamine in asthma were evaluated.

MATERIALS AND METHODS

Thirty-two Sprague-Dawley (SD) rats were used, asthma was induced by injecting intraperitoneally with a mixture of Al(OH)₃ (100 mg) and ovalbumin (OA; 1 mg/kg), further exposing them to a 2% OA aerosol for 1 week. All animals were divided into four groups: control, asthma, and evodiamine 40 and 80 mg/kg p.o. treated group. Serum levels of inflammatory cytokines, interferon gamma (IFN-γ), and immunoglobulin E (IgE) and infiltrations of inflammatory cells in the bronchoalveolar lavage fluid (BALF) of the animals were determined. The thickness of the smooth muscle layer and airway wall in the intact small bronchioles of asthmatic rats was examined as well.

RESULTS

Cytokine levels in the serum and BALF were lower in the evodiamine-treated group than in the asthma group. Evodiamine treatment reduced IgE and IFN-γ levels as well as the inflammatory cell infiltrate in the lung tissue of asthmatic rats. The thickness of the smooth muscle layer and airway wall of intact small bronchioles was less in the evodiamine-treated group than in the asthma group. Lower levels of TLR-4, MyD88, NF-κB, and HMGB1 mRNA in lung tissue were measured in the evodiamine-treated group than in the asthma group.

DISCUSSION AND CONCLUSION

The effect of evodiamine treatment protects the asthma, as evodiamine reduces airway inflammation and remodelling in the lung tissue by downregulating the HMGB1/NF-κB/TLR-4 pathway in asthma.

Human microphysiological models of airway and alveolar epithelia

Human organ-on-a-chip models are powerful tools for preclinical research that can be used to study the mechanisms of disease and evaluate new targets for therapeutic intervention. Lung-on-a-chip models have been one of the most well-characterized designs in this field and can be altered to evaluate various types of respiratory disease and to assess treatment candidates prior to clinical testing. These systems are capable of overcoming the flaws of conventional two-dimensional (2-D) cell culture and in vivo animal testing due to their ability to accurately recapitulate the in vivo microenvironment of human tissue with tunable material properties, microfluidic integration, delivery of precise mechanical and biochemical cues, and designs with organ-specific architecture. In this review, we first describe an overview of currently available lung-on-a-chip designs. We then present how recent innovations in human stem cell biology, tissue engineering, and microfabrication can be used to create more predictive human lung-on-a-chip models for studying respiratory disease. Finally, we discuss the current challenges and future directions of lung-on-a-chip designs for in vitro disease modeling with a particular focus on immune and multiorgan interactions.

Caspase-11 regulates lung inflammation in response to house dust mites

Asthma is an inflammatory lung disorder characterized by mucus hypersecretion, cellular infiltration, and bronchial hyper-responsiveness. House dust mites (HDM) are the most prevalent cause of allergic sensitization. Canonical and noncanonical inflammasomes are multiprotein complexes that assemble in response to pathogen or danger-associated molecular patterns (PAMPs or DAMPs). Murine caspase-11 engages the noncanonical inflammasome. We addressed the role of caspase-11 in mediating host responses to HDM and subsequent allergic inflammation using caspase-11-/- mice, which lack caspase-11 while express caspase-1. We found that HDM induce caspase-11 expression in vitro. The presence of IL-4 and IL-13 promote caspase-11 expression. Additionally, caspase-11-/- macrophages show reduced release of IL-6, IL-12, and KC, and express lower levels of costimulatory molecules (e.g., CD40, CD86 and MHCII) in response to HDM stimulation. Notably, HDM sensitization of caspase-11-/- mice resulted in similar levels of IgE responses and hypothermia in response to nasal HDM challenge compared to WT. However, analysis of cell numbers and cytokines in bronchiolar alveolar lavage fluid (BALF) and histopathology of representative lung segments demonstrate altered inflammatory responses and reduced neutrophilia in the airways of the caspase-11-/- mice. These findings indicate that caspase-11 regulates airway inflammation in response to HDM exposure.

Corticosteroid insensitivity persists in the absence of STAT1 signaling in severe allergic airway inflammation

Corticosteroid insensitivity in asthma limits the ability to effectively manage severe asthma, which is characterized by persistent airway inflammation, airway hyperresponsiveness (AHR), and airflow obstruction despite corticosteroid treatment. Recent reports indicate that corticosteroid insensitivity is associated with increased interferon-γ (IFN-γ) levels and T-helper (Th) 1 lymphocyte infiltration in severe asthma. Signal transducer and activator of transcription 1 (STAT1) activation by IFN-γ is a key signaling pathway in Th1 inflammation; however, its role in the context of severe allergic airway inflammation and corticosteroid sensitivity remains unclear. In this study, we challenged wild-type (WT) and Stat1^-/- mice with mixed allergens (MA) augmented with c-di-GMP [bis-(3'-5')-cyclic dimeric guanosine monophosphate], an inducer of Th1 cell infiltration with increased eosinophils, neutrophils, Th1, Th2, and Th17 cells. Compared with WT mice, Stat1^-/- had reduced neutrophils, Th1, and Th17 cell infiltration. To evaluate corticosteroid sensitivity, mice were treated with either vehicle, 1 or 3 mg/kg fluticasone propionate (FP). Corticosteroids significantly reduced eosinophil infiltration and cytokine levels in both c-di-GMP + MA-challenged WT and Stat1^-/- mice. However, histological and functional analyses show that corticosteroids did not reduce airway inflammation, epithelial mucous cell abundance, airway smooth muscle mass, and AHR in c-di-GMP + MA-challenged WT or Stat1^-/- mice. Collectively, our data suggest that increased Th1 inflammation is associated with a decrease in corticosteroid sensitivity. However, increased airway pathology and AHR persist in the absence of STAT1 indicate corticosteroid insensitivity in structural airway cells is a STAT1 independent process.

CC16 deficiency in the context of early life Mycoplasma pneumoniae infection results in augmented airway responses in adult mice

Studies have shown that club cell secretory protein (CC16) plays important protective roles in the lungs, yet its complete biological functions are unclear. We devised a translational mouse model in order to investigate the impact of early life infections, in the context of CC16 deficiency, on lung function in adult mice. CC16 sufficient (WT) and deficient (CC16^-/-) mice were infected with Mycoplasma pneumoniae (Mp) as weanlings and assessed as adults (early life infection model; ELIM) and compared to adult mice infected for only three days (adult infection model; AIM). CC16^-/- Mp-infected mice had significantly increased airway hyperresponsiveness (AHR) in both models compared to WT mice. However, CC16^-/- mice infected in early life (ELIM) displayed significantly increased AHR compared to CC16^-/- mice infected in adulthood (AIM). In stark contrast, lung function in ELIM WT mice returned to levels similar to saline-treated controls. While WT mice cleared Mp infection in the ELIM, CC16^-/- mice remained colonized with Mp throughout the model, which likely contributed to increased airway remodeling and persistence of Muc5ac expression. When CC16^-/- mouse tracheal epithelial cells (MTECs) were infected with Mp, increased Mp colonization and collagen gene expression were also detected compared to WT cells, suggesting that CC16 plays a protective role during Mp infection, in part through epithelial-driven host defense mechanisms.

Pathogenesis, clinical features of asthma COPD overlap (ACO), and therapeutic modalities

Both asthma and COPD are heterogeneous diseases identified by characteristic symptoms and functional abnormalities, with airway obstruction common in both diseases. Asthma COPD overlap (ACO) does not define a single disease but is a descriptive term for clinical use that includes several overlapping clinical phenotypes of chronic airways disease with different underlying mechanisms. This literature review was initiated to describe published studies, identify gaps in knowledge, and propose future research goals regarding the disease pathology of ACO, especially the airway remodelling changes and inflammation aspects. Airway remodelling occurs in asthma and COPD, but there are differences in the structures affected and the prime anatomic site at which they occur. Reticular basement membrane thickening and cellular infiltration with eosinophils and T-helper (CD4+) lymphocytes are prominent features of asthma. Epithelial squamous metaplasia, airway wall fibrosis, emphysema, bronchoalveolar lavage (BAL) neutrophilia and (CD8+) T-cytotoxic lymphocyte infiltrations in the airway wall are features of COPD. There is no universally accepted definition of ACO, nor are there clearly defined pathological characteristics to differentiate from asthma and COPD. Understanding etiological concepts within the purview of inflammation and airway remodelling changes in ACO would allow better management of these patients.

Synthesis and in vitro evaluation of anti-inflammatory, antioxidant, and anti-fibrotic effects of new 8-aminopurine-2,6-dione-based phosphodiesterase inhibitors as promising anti-asthmatic agents

Phosphodiesterase (PDE) inhibitors are currently an extensively studied group of compounds that can bring many benefits in the treatment of various inflammatory and fibrotic diseases, including asthma. Herein, we describe a series of novel N'-phenyl- or N'-benzylbutanamide and N'-arylidenebutanehydrazide derivatives of 8-aminopurine-2,6-dione (27-43) and characterized them as prominent pan-PDE inhibitors. Most of the compounds exhibited antioxidant and anti-inflammatory activity in lipopolysaccharide (LPS)-induced murine macrophages RAW264.7. The most active compounds (32-35 and 38) were evaluated in human bronchial epithelial cells (HBECs) derived from asthmatics. To better map the bronchial microenvironment in asthma, HBECs after exposure to selected 8-aminopurine-2,6-dione derivatives were incubated in the presence of two proinflammatory and/or profibrotic factors: transforming growth factor type β (TGF-β) and interleukin 13 (IL-13). Compounds 32-35 and 38 significantly reduced both IL-13- and TGF-β-induced expression of proinflammatory and profibrotic mediators, respectively. Detailed analysis of their inhibition preferences for selected PDEs showed high affinity for isoenzymes important in the pathogenesis of asthma, including PDE1, PDE3, PDE4, PDE7, and PDE8. The presented data confirm that structural modifications within the 7 and 8 positions of the purine-2,6-dione core result in obtaining preferable pan-PDE inhibitors which in turn exert an excellent anti-inflammatory and anti-fibrotic effect in the bronchial epithelial cells derived from asthmatic patients. This dual-acting pan-PDE inhibitors constitute interesting and promising lead structures for further anti-asthmatic agent discovery.

Airway smooth muscle remodelling in mild and moderate equine asthma

BACKGROUND

Airway smooth muscle remodelling in severe equine asthma includes both thickening of airway smooth muscle, resulting from hyperplasia and hypertrophy, and changes in contractility. However, airway smooth muscle changes have not been studied in milder forms of the disease.

OBJECTIVES

To investigate bronchial smooth muscle remodelling in horses with mild and moderate asthma (MEA).

STUDY DESIGN

Retrospective case-control study.

METHODS

The endobronchial biopsies from 18 horses with MEA referred to the Equine Hospital of the Université de Montréal and from seven healthy age-matched control horses were studied. The diagnosis was based on clinical signs and bronchoalveolar lavage fluid cytology. Airway smooth muscle cell proliferation was measured by quantifying the expression of the proliferating cell nuclear antigen (PCNA) using immunohistochemistry and histomorphometry. The expression of the (+)insert smooth muscle myosin heavy chain (SMMHC) isoform, an hypercontractile protein, was assessed by RT-qPCR.

RESULTS

Expression of the (+)insert SMMHC isoform in airway smooth muscle was approximately 1.5 times greater in horses with MEA compared with controls (P = .02, mean difference 0.01). Although there were no differences between groups in the proliferation of airway smooth muscle cells (P = .4) or myocyte density (P = .3, mean difference -0.6), the percentage of proliferating myocytes was correlated to pulmonary neutrophilia in horses with neutrophilic inflammation (P = .01, r = .80) and to the expression of the (+)insert SMMHC isoform in asthmatic horses (P = .03, r = .66).

MAIN LIMITATIONS

Small cohorts of horses were studied, and conclusions are limited to the central airways.

CONCLUSIONS

These results confirm the presence of bronchial smooth muscle remodelling in mild forms of equine asthma and pave the way for the development of biomarkers to measure asthma progression and response to therapy.

Augmented angiogenic transcription factor, SOX18, is associated with asthma exacerbation

BACKGROUND

Asthma characterized by airway hyperresponsiveness, inflammation, fibrosis, and angiogenesis. SRY-related HMG-box 18 (SOX18) is an important transcription factor involved in angiogenesis, tissue injury, wound-healing, and in embryonic cardiovascular and lymphatic vessels development. The role of angiogenic transcription factors, SOX18 and the related, prospero homeobox 1 (PROX1) and chicken ovalbumin upstream promoter transcription factor II (COUP-TFII), in asthma has had limited study.

OBJECTIVE

In this study, we aimed to elucidate the role of SOX18 in the pathogenesis of bronchial asthma.

METHODS

Plasma SOX18 protein was measured in control subjects, and subject with stable or exacerbated asthma. SOX18, PROX1, and COUP-TFII protein was measured by western blot, and immunohistochemistry in a murine model of ovalbumin-induced allergic asthma (OVA). SOX18, PROX1, and COUP-TFII protein was measured in lung human microvascular endothelial cells (HMVEC-L) and normal human bronchial epithelial (NHBE) cells treated with house dust mite (Der p1).

RESULTS

Plasma SOX18 tended to be higher in subject with asthma compared to control subjects and increased more during exacerbation as compared to stable disease. In mice, OVA challenge lead to increased lung SOX18, PROX1, COUP-TFII, mucous gland hyperplasia and submucosal collagen. In NHBE cells, SOX18, PROX1 and COUP-TFII increased following Der p1 treatment. SOX18 protein increased in HMVEC-L following Der p1 treatment.

CONCLUSION

These results suggest that SOX18 may be involved in asthma pathogenesis and be associated with asthma exacerbation.

Eosinophils, a Jack of All Trades in Immunity: Therapeutic Approaches for Correcting Their Functional Disorders

BACKGROUND AND OBJECTIVE

Eosinophils are primitive myeloid cells derived from bonemarrow precursors and require the intervention of interleukin (IL)-5 for their survival and persistence in blood and tissues. Under steady-state conditions, they contribute to immune regulation and homeostasis. Under pathological circumstances, eosinophils are involved in host protection against parasites and participate in allergy and inflammation.

DISCUSSION

Mostly, in asthma, eosinophils provoke airway damage via the release of granule contents and IL-13 with mucus hypersecretion and differentiation of goblet cells. Then, tissue remodeling follows with the secretion of transforming growth factor-β. Eosinophils are able to kill helminth larvae acting as antigen-presenting cells with the involvement of T helper (h)-2 cells and subsequent antibody response. However, they also exert pro-worm activity with the production of suppressive cytokine (IL- 10 and IL-4) and inhibition of nitric oxide. Eosinophils may play a pathogenic role in the course of chronic and autoimmune disease, e.g., inflammatory bowel disease and eosinophilic gastroenteritis, regulating Th2 responses and promoting a profibrotic effect. In atopic dermatitis, eosinophils are commonly detected and may be associated with disease severity. In cutaneous spontaneous urticaria, eosinophils participate in the formation of wheals, tissue remodeling and modifications of vascular permeability. With regard to tumor growth, it seems that IgE can exert anti-neoplastic surveillance via mast cell and eosinophil-mediated cytotoxicity, the so-called allergo-oncology. From a therapeutic point of view, monoclonal antibodies directed against IL-5 or the IL-5 receptors have been shown to be very effective in patients with severe asthma. Finally, as an alternative treatment, polyphenols for their anti-inflammatory and anti-allergic activities seem to be effective in reducing serum IgE and eosinophil count in bronchoalveolar lavage in murine asthma.

CONCLUSION

Eosinophils are cells endowed with multiple functions and their modulation with monoclonal antibodies and nutraceuticals may be effective in the treatment of chronic disease.

Hypoxia-induced preadipocyte factor 1 expression in human lung fibroblasts through ERK/PEA3/c-Jun pathway

Background

Several studies have reported that hypoxia plays a pathological role in severe asthma and tissue fibrosis. Our previous study showed that hypoxia induces A disintegrin and metalloproteinase 17 (ADAM17) expression in human lung fibroblasts. Moreover, preadipocyte factor 1 (Pref-1) is cleaved by ADAM17, which participates in adipocyte differentiation. Furthermore, Pref­1 overexpression is involved in tissue fibrosis including liver and heart. Extracellular signal-regulated kinase (ERK) could active downstram gene expression through polyoma enhancer activator 3 (PEA3) phosphorylation. Studies have demonstrated that PEA3 and activator protein 1 (AP-1) play crucial roles in lung fibrosis, and the Pref-1 promoter region contains PEA3 and AP-1 binding sites as predicted. However, the roles of ERK, PEA3, and AP-1 in hypoxia-stimulated Pref-1 expression in human lung fibroblasts remain unknown.

Methods

The protein expression in ovalbumin (OVA)-induced asthmatic mice was performed by immunohistochemistry and immunofluorescence. The protein expression or the mRNA level in human lung fibroblasts (WI-38) was detected by western blot or quantitative PCR. Small interfering (si) RNA was used to knockdown gene expression. The collaboration with PEA3 and c-Jun were determined by coimmunoprecipitation. Translocation of PEA3 from the cytosol to the nucleus was observed by immunocytochemistry. The binding ability of PEA3 and AP-1 to Pref-1 promoter was assessed by chromatin immunoprecipitation.

Results

Pref-1 and hypoxia-inducible factor 1α (HIF-1α) were expressed in the lung sections of OVA-treated mice. Colocalization of PEA3 and Fibronectin was detected in lung sections from OVA-treated mice. Futhermore, Hypoxia induced Pref­1 protein upregulation and mRNA expression in human lung fibroblasts (WI­38 cells). In 60 confluent WI-38 cells, hypoxia up-regulated HIF-1α and Pref-1 protein expression. Moreover, PEA3 small interfering (si) RNA decreased the expression of hypoxia-induced Pref­1 in WI­38 cells. Hypoxia induced PEA3 phosphorylation, translocation of PEA3 from the cytosol to the nucleus, PEA3 recruitment and AP-1 binding to the Pref­1 promoter region, and PEA3-luciferase activity. Additionally, hypoxia induced c-Jun-PEA3 complex formation. U0126 (an ERK inhibitor), curcumin (an AP­1 inhibitor) or c-Jun siRNA downregulated hypoxia-induced Pref-1 expression.

Conclusions

These results implied that ERK, PEA3, and AP­1 participate in hypoxia­induced Pref­1 expression in human lung fibroblasts.

Lung Pericytes in Pulmonary Vascular Physiology and Pathophysiology

Pericytes are mesenchymal-derived mural cells localized within the basement membrane of pulmonary and systemic capillaries. Besides structural support, pericytes control vascular tone, produce extracellular matrix components, and cytokines responsible for promoting vascular homeostasis and angiogenesis. However, pericytes can also contribute to vascular pathology through the production of pro-inflammatory and pro-fibrotic cytokines, differentiation into myofibroblast-like cells, destruction of the extracellular matrix, and dissociation from the vessel wall. In the lung, pericytes are responsible for maintaining the integrity of the alveolar-capillary membrane and coordinating vascular repair in response to injury. Loss of pericyte communication with alveolar capillaries and a switch to a pro-inflammatory/pro-fibrotic phenotype are common features of lung disorders associated with vascular remodeling, inflammation, and fibrosis. In this article, we will address how to differentiate pericytes from other cells, discuss the molecular mechanisms that regulate the interactions of pericytes and endothelial cells in the pulmonary circulation, and the experimental tools currently used to study pericyte biology both in vivo and in vitro. We will also discuss evidence that links pericytes to the pathogenesis of clinically relevant lung disorders such as pulmonary hypertension, idiopathic lung fibrosis, sepsis, and SARS-COVID. Future studies dissecting the complex interactions of pericytes with other pulmonary cell populations will likely reveal critical insights into the origin of pulmonary diseases and offer opportunities to develop novel therapeutics to treat patients afflicted with these devastating disorders. © 2021 American Physiological Society. Compr Physiol 11:2227-2247, 2021.

Andrographolide Inhibition of Th17-Regulated Cytokines and JAK1/STAT3 Signaling in OVA-Stimulated Asthma in Mice

Asthma has long been considered a disease of airway inflammation. The excessive or prolonged production of inflammatory mediators can result in airway remodeling and severe clinical syndromes such as dyspnea or even apnea. Therefore, pharmaceutical intervention is required to restrain the excessive release of such inflammatory mediators in control of asthma. Novel therapeutics and mechanistic insight are sought for the management of this chronic inflammatory disease. Andrographolide (AG) is a type of diterpenoid ester compound and is reported to demonstrate multiple properties such as antioxidation and anti-inflammation. However, the anti-inflammatory capacity of AG by regulating immunologic function in airway of asthma has not been fully studied to date. Therefore, this study investigates whether AG is capable of suppressing the inflammatory response of asthma in OVA-stimulated mice and the mechanism by which this is achieved. Animals were randomly divided into 4 groups: control group, OVA model group, OVA + AG (0.1 mg/ml) group, and OVA + dimethylsulfoxide (DMSO) group. The serum, BALF, and lung tissue of the mice were collected separately for the administration of ELISA, rt-PCR, western blot and pathological section and staining. We found that AG attenuated the OVA-induced production of IL-6, IL-17A, IL-17F, and RORγt; inhibited the OVA-mediated phosphorylation of JAK 1 and STAT3; and alleviated airway remodeling and the neutrophil infiltration of lung tissue. We conclude that AG inhibits the inflammatory response of asthma in OVA-stimulated mice by blocking the activation of Th17-regulated cytokines and the JAK1/STAT3 signaling pathway.

Evolution of proteomics technologies for understanding respiratory syncytial virus pathogenesis

Introduction: Respiratory syncytial virus (RSV) is a major human pathogen associated with long term morbidity. RSV replication occurs primarily in the epithelium, producing a complex cellular response associated with acute inflammation and long-lived changes in pulmonary function and allergic disease. Proteomics approaches provide important insights into post-transcriptional regulatory processes including alterations in cellular complexes regulating the coordinated innate response and epigenome.Areas covered: Peer-reviewed proteomics studies of host responses to RSV infections and proteomics techniques were analyzed. Methodologies identified include 1)." bottom-up" discovery proteomics, 2). Organellar proteomics by LC-gel fractionation; 3). Dynamic changes in protein interaction networks by LC-MS; and 4). selective reaction monitoring MS. We introduce recent developments in single-cell proteomics, top-down mass spectrometry, and photo-cleavable surfactant chemistries that will have impact on understanding how RSV induces extracellular matrix (ECM) composition and airway remodeling.Expert opinion: RSV replication induces global changes in the cellular proteome, dynamic shifts in nuclear proteins, and remodeling of epigenetic regulatory complexes linked to the innate response. Pathways discovered by proteomics technologies have led to deeper mechanistic understanding of the roles of heat shock proteins, redox response, transcriptional elongation complex remodeling and ECM secretion remodeling in host responses to RSV infections and pathological sequelae.

Distinct Patterns of Tissue Remodeling and Their Prognostic Role in Chronic Rhinosinusitis

INTRODUCTION

Tissue remodeling refers to structural changes that occur in damaged tissue and is associated with disease severity in asthma. However, the characteristics of tissue remodeling and its prognostic role in chronic rhinosinusitis (CRS) remain unclear. In this report, we evaluated the clinical implications of tissue remodeling in CRS.

METHODS

We performed a retrospective cohort study of adult patients who underwent endoscopic sinus surgery for bilateral CRS. The histopathology of sinus mucosa was determined by evaluating the inflammatory cell count and tissue remodeling markers (squamous metaplasia, subepithelial gland proliferation, basement membrane [BM] thickening, stromal edema, and fibrosis). Eosinophilic CRS (ECRS) was defined as an eosinophil count >15/high-power field in the biopsied tissue. Patient characteristics, allergy test grade, preoperative Lund-Mackay score (LMS), and pre- and postoperative Lund-Kennedy scores (LKSs) were analyzed.

RESULTS

Of the identified patients, 59.1% were classified as ECRS and the remaining 40.9% as non-ECRS. Regarding tissue remodeling markers, stromal edema was seen in 90.9%, BM thickening in 63.6%, and stromal fibrosis in 34.1% of patients. In cases with stromal edema and BM thickening, greater tissue eosinophilia was observed, while stromal fibrosis decreased tissue eosinophilia (p < 0.05). Prognostically, subepithelial gland proliferation alone was an independent risk factor for poor postoperative endoscopic findings (odds ratio: 8.250, 95% confidence interval: 1.128-60.319, p = 0.038).

CONCLUSIONS

Tissue eosinophilia was commonly associated with BM thickening and stromal edema. Subepithelial gland proliferation predicted a poor surgical prognosis in CRS. These findings imply that tissue remodeling provides additional information not only on the CRS endotype but also on the postsurgical prognosis.

New Avenues for Phosphodiesterase Inhibitors in Asthma

Introduction

Phosphodiesterases (PDEs) are isoenzymes ubiquitously expressed in the lungs where they catalyse cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (GMP), which are fundamental second messengers in asthma, thereby regulating the intracellular concentrations of these cyclic nucleotides, their signaling pathways and, consequently, myriad biological responses. The superfamily of PDEs is composed of 11 families with a distinct substrate specificity, molecular structure and subcellular localization. Experimental studies indicate a possible role in asthma mainly for PDE3, PDE4, PDE5 and PDE7. Consequently, drugs that inhibit PDEs may offer novel therapeutic options for the treatment of this disease.

Areas Covered

In this article, we describe the progress made in recent years regarding the possibility of using PDE inhibitors in the treatment of asthma.

Expert Opinion

Many data indicate the potential benefits of PDE inhibitors as an add-on treatment especially in severe asthma due to their bronchodilator and/or anti-inflammatory activity, but no compound has yet reached the market as asthma treatment mainly because of their limited tolerability. Therefore, there is a growing interest in developing new PDE inhibitors with an improved safety profile. In particular, the research is focused on the development of drugs capable of interacting simultaneously with different PDEs, or to be administered by inhalation. CHF 6001 and RPL554 are the only molecules that currently are under clinical development but there are several new agents with interesting pharmacological profiles. It will be stimulating to assess the impact of such agents on individual treatable traits in specially designed studies.

The SWI/SNF-Related, Matrix Associated, Actin-Dependent Regulator of Chromatin A4 Core Complex Represses Respiratory Syncytial Virus-Induced Syncytia Formation and Subepithelial Myofibroblast Transition

Epigenetics plays an important role in the priming the dynamic response of airway epithelial cells to infectious and environmental stressors. Here, we examine the epigenetic role of the SWI/SNF Related, Matrix Associated, Actin Dependent Regulator of Chromatin A4 (SMARCA4) in the epithelial response to RSV infection. Depletion of SMARCA4 destabilized the abundance of the SMARCE1/ARID1A SWI/SNF subunits, disrupting the innate response and triggering a hybrid epithelial/mesenchymal (E/M) state. Assaying SMARCA4 complex-regulated open chromatin domains by transposase cleavage -next generation sequencing (ATAC-Seq), we observed that the majority of cleavage sites in uninfected cells have reduced chromatin accessibility. Paradoxically, SMARCA4 complex-depleted cells showed enhanced RSV-inducible chromatin opening and gene expression in the EMT pathway genes, MMP9, SNAI1/2, VIM, and CDH2. Focusing on the key MMP9, we observed that SMARCA4 complex depletion reduced basal BRD4 and RNA Polymerase II binding, but enhanced BRD4/Pol II binding in response to RSV infection. In addition, we observed that MMP9 secretion in SMARCA4 complex deficient cells contributes to mesenchymal transition, cellular fusion (syncytia) and subepithelial myofibroblast transition. We conclude the SMARCA4 complex is a transcriptional repressor of epithelial plasticity, whose depletion triggers a hybrid E/M state that affects the dynamic response of the small airway epithelial cell in mucosal remodeling via paracrine MMP9 activity.

Human rhinovirus 16 induces antiviral and inflammatory response in the human vascular endothelium

The effect of rhinovirus on airway epithelium is very well described. However, its influence on the vascular endothelium is unknown. The current study assesses the effect of rhinovirus HRV16 on the antiviral and inflammatory response in the human vascular endothelial cells (ECs). HRV16 increased IFN-β, RANTES, and IP-10 mRNA expression and protein release. HRV16 copy number in ECs reached maximal value 10 h after incubation. Increase in virus copies was accompanied by the enhancement of Toll- and RIG-I-like receptors: TLR3, RIG-I, and MDA5. Additionally, HRV16 increased OAS-1 and PKR mRNA expression, enzymes responsible for virus degradation and inhibition of replication. ICAM-1 blockade decreased HRV16 copy number in ECs and inhibited IFN-β, RANTES, IP-10, OAS1, PKR, TLR3, RIG-I, and MDA5 mRNA expression increase upon subsequent induction with HRV16. The vascular endothelium may be infected by human rhinovirus and generate antiviral and inflammatory innate response. Results of the study indicate the possible involvement of the vascular endothelium in the immunopathology of rhinoviral airway infections.

Role of Collagen in Airway Mechanics

Collagen is the most abundant airway extracellular matrix component and is the primary determinant of mechanical airway properties. Abnormal airway collagen deposition is associated with the pathogenesis and progression of airway disease. Thus, understanding how collagen affects healthy airway tissue mechanics is essential. The impact of abnormal collagen deposition and tissue stiffness has been an area of interest in pulmonary diseases such as cystic fibrosis, asthma, and chronic obstructive pulmonary disease. In this review, we discuss (1) the role of collagen in airway mechanics, (2) macro- and micro-scale approaches to quantify airway mechanics, and (3) pathologic changes associated with collagen deposition in airway diseases. These studies provide important insights into the role of collagen in airway mechanics. We summarize their achievements and seek to provide biomechanical clues for targeted therapies and regenerative medicine to treat airway pathology and address airway defects.

Riparin II potentials the effect of ephedrine on inflammation and remodelling in the airway of rats suffering from asthma by regulating transforming growth factor-β/Smad3 signalling pathway

Asthma is a chronic obstructive lung disorder involving hyperresponsive lung tissue. This study evaluated the protective effects of riparin II against asthma and determined the synergistic effects of riparin II with ephedrine in treatment of asthma. Asthma was induced by intraperitoneal injection of Al(OH)3 (100 mg) with ovalbumin 1 mg/kg and subsequent exposure to 2% ovalbumin aerosol for 1 week. All animals were treated with riparin II 50 mg/kg and ephedrine 25 mg/kg alone and in combination for the duration of the study. Interleukin levels were assessed in the serum and bronchoalveolar lavage fluid (BALF) of asthmatic rats, while inflammatory cell infiltration was determined in the lungs. Airway remodelling was determined by assessing the lung tissue expression levels of transforming growth factor beta 1 (TGF-β1), Smad, and collagen I in asthmatic rats. There were lower levels of cytokines in the serum and BALF in riparin II-treated rats than in negative control rats. Moreover, inflammatory cell and IgE levels were reduced while interferon level was enhanced in the lungs of riparin II-treated rats, compared to negative control rats. These data reveal that treatment with riparin II ameliorates the altered expression of TGF-β1, Smad, and collagen I in lung tissue of asthmatic rats. In conclusion, riparin II treatment alone and in combination with ephedrine ameliorated the hyperresponsiveness of lung tissue due to reductions in airway remodelling and inflammation in asthmatic rats.

Effects of Inhalation of STIM-Orai Antagonist SKF 96365 on Ovalbumin-Induced Airway Remodeling in Guinea Pigs

Airway remodeling (AR) consists of wall thickening and hyperreactivity. STIM (stromal interaction molecule) and Orai protein pathways mediate extracellular Ca²⁺ signals involved in AR. This study aims to define the effects on AR of the STIM-Orai antagonist SKF 96365 given by inhalation in three increasing doses in ovalbumin-induced AR. In the control group, the antiasthmatic budesonide and salbutamol were given in the same model. The airway structure was evaluated by histological and immunohistochemistry and reactivity by specific airway resistance, contraction strength of isolated airway smooth muscles, and mucociliary clearance expressed by ciliary beating frequency. The immuno-biochemical markers of chronic inflammation were evaluated by BioPlex and ELISA assays. The AR was mediated by inflammatory cytokines and growth factors. The findings show significant anti-remodeling effects of SKF 96365, which were associated with a decrease in airway hyperreactivity. The anti-remodeling effect of SKF 96365 was mediated via the suppression of IL-4, IL-5, and IL-13 synthesis, and IL-12-INF-γ-TGF-β pathway. The budesonide-related AR suppression had to do with a decrease in proinflammatory cytokines and an increase in the anti-inflammatory IL-10, with negligible influence on growth factors synthesis and mucous glands activity.

Exposure to Polyhexamethylene Guanidine Exacerbates Bronchial Hyperresponsiveness and Lung Inflammation in a Mouse Model of Ovalbumin-Induced Asthma

Humidifier disinfectants (HDs) exposure has now been associated with acute lung injury and pulmonary fibrosis; polyhexamethylene guanidine (PHMG) has been confirmed to cause severe lung inflammation and fibrosis in mice. Recent evidence also indicates that HDs exposure increases the asthma risk in children, but the underlying mechanisms remain unclear. We aimed to investigate the effects of PHMG exposure on asthma in mice and the potential underlying mechanisms. BALB/c mice were intranasally administered PHMG (0.1 mg/kg/day; 5 days per week) during 2 episodes of ovalbumin (OVA) sensitization and were then challenged with 1% OVA by inhalation. Bronchial hyperresponsiveness (BHR), inflammatory cell influx into bronchoalveolar lavage (BAL) fluid, serum total and OVA-specific immunoglobulin (Ig) E levels, and histopathological changes in the lung were analyzed. The levels of asthma-related cytokines and chemokines were assayed in the lung tissues to evaluate possible mechanisms. Exposure to PHMG following OVA sensitization and challenge significantly enhanced BHR, inflammatory cell counts in BAL fluid, airway inflammation, and total serum IgE levels in the asthma mouse model. In addition, the levels of chemokine ligand (CCL) 11 and serpine F1/pigment epithelium-derived factor (SERPINF1) were significantly elevated in the lungs of these mice compared to those in the control and OVA-treated only groups. Our findings suggest that PHMG can enhance the development of allergic responses and lung inflammation via CCL11- and SERPINF1-induced signaling in a mouse model of asthma.

Nanoapproaches to Modifying Epigenetics of Epithelial Mesenchymal Transition for Treatment of Pulmonary Fibrosis

Idiopathic Pulmonary Fibrosis (IPF) is a chronically progressive interstitial lung that affects over 3 M people worldwide and rising in incidence. With a median survival of 2-3 years, IPF is consequently associated with high morbidity, mortality, and healthcare burden. Although two antifibrotic therapies, pirfenidone and nintedanib, are approved for human use, these agents reduce the rate of decline of pulmonary function but are not curative and do not reverse established fibrosis. In this review, we discuss the prevailing epithelial injury hypothesis, wherein pathogenic airway epithelial cell-state changes known as Epithelial Mesenchymal Transition (EMT) promotes the expansion of myofibroblast populations. Myofibroblasts are principal components of extracellular matrix production that result in airspace loss and mortality. We review the epigenetic transition driving EMT, a process produced by changes in histone acetylation regulating mesenchymal gene expression programs. This mechanistic work has focused on the central role of bromodomain-containing protein 4 in mediating EMT and myofibroblast transition and initial preclinical work has provided evidence of efficacy. As nanomedicine presents a promising approach to enhancing the efficacy of such anti-IPF agents, we then focus on the state of nanomedicine formulations for inhalable delivery in the treatment of pulmonary diseases, including liposomes, polymeric nanoparticles (NPs), inorganic NPs, and exosomes. These nanoscale agents potentially provide unique properties to existing pulmonary therapeutics, including controlled release, reduced systemic toxicity, and combination delivery. NP-based approaches for pulmonary delivery thus offer substantial promise to modify epigenetic regulators of EMT and advance treatments for IPF.

Regulatory T cells mediated immunomodulation during asthma: a therapeutic standpoint

Asthma is an inflammatory disease of the lung airway network, which is initiated and perpetuated by allergen-specific CD4⁺ T cells, IgE antibodies, and a massive release of Th2 cytokines. The most common clinical manifestations of asthma progression include airway inflammation, pathological airway tissue and microvascular remodeling, which leads to airway hyperresponsiveness (AHR), and reversible airway obstruction. In addition to inflammatory cells, a tiny population of Regulatory T cells (Tregs) control immune homeostasis, suppress allergic responses, and participate in the resolution of inflammation-associated tissue injuries. Preclinical and clinical studies have demonstrated a tremendous therapeutic potential of Tregs in allergic airway disease, which plays a crucial role in immunosuppression, and rejuvenation of inflamed airways. These findings supported to harness the immunotherapeutic potential of Tregs to suppress airway inflammation and airway microvascular reestablishment during the progression of the asthma disease. This review addresses the therapeutic impact of Tregs and how Treg mediated immunomodulation plays a vital role in subduing the development of airway inflammation, and associated airway remodeling during the onset of disease.

iTRAQ-based proteomic analysis reveals potential serum biomarkers of allergic and nonallergic asthma

BACKGROUND

Asthma is heterogeneous disease with different phenotypes, endotypes and severities. Definition of these subgroups requires the identification of biomarkers in biological samples, and serum proteomics is a useful and minimally invasive method for this purpose. Therefore, the aim of this study was to detect serum proteins whose abundance is distinctively associated with different asthma phenotypes (allergic vs nonallergic) or severities.

METHODS

For each group of donors (32 healthy controls, 43 allergic rhinitis patients and 192 asthmatics with different phenotypes and severities), we generated two pools of sera that were analysed by a shotgun MS approach based on combinatorial peptide ligand libraries and iTRAQ-LC-MS/MS.

RESULTS

MS analyses identified 18 proteins with a differential abundance. Functional/network study of these proteins identified key processes for asthma pathogenesis, such as complement activation, extracellular matrix organization, platelet activation and degranulation, or post-translational protein phosphorylation. Furthermore, our results highlighted an enrichment of the "Regulation of Insulin-like Growth Factor (IGF) transport and uptake by Insulin-like Growth Factor Binding Proteins (IGFBPs)" route in allergic asthma and the lectin pathway of complement activation in nonallergic asthma. Thus, several proteins (eg IGFALS, HSPG2, FCN2 or MASP1) displayed a differential abundance between the different groups of donors. Particularly, our results revealed IGFALS as a useful biomarker for moderate-severe allergic asthma.

CONCLUSION

Our data suggest a set of serum biomarkers, especially IGFALS, capable of differentiating allergic from nonallergic asthma. These proteins reveal different pathophysiological mechanisms and may be useful in the future for diagnosis, prognosis or targeted therapy purposes.

Enhanced mitophagy in bronchial fibroblasts from severe asthmatic patients

Background

Sub-epithelial fibrosis is a characteristic feature of airway remodeling in asthma which correlates with disease severity. Current asthma medications are ineffective in treating fibrosis. In this study, we aimed to investigate the mitochondrial phenotype in fibroblasts isolated from airway biopsies of non-asthmatic and severe asthmatic subjects by examining mitophagy as a mechanism contributing to fibroblast persistence and thereby, fibrosis in severe asthma.

Methods

Bioinformatics analysis of publicly available transcriptomic data was performed to identify the top enriched pathways in asthmatic fibroblasts. Endogenous expression of mitophagy markers in severe asthmatic and non-asthmatic fibroblasts was determined using qRT-PCR, western blot and immunofluorescence. Mitophagy flux was examined by using lysosomal protease inhibitors, E64d and pepstatin A. Mitochondrial membrane potential and metabolic activity were also evaluated using JC-1 assay and MTT assay, respectively.

Results

Bioinformatics analysis revealed the enrichment of Pink/Parkin-mediated mitophagy in asthmatic fibroblasts compared to healthy controls. In severe asthmatic fibroblasts, the differential expression of mitophagy genes, PINK1 and PRKN, was accompanied by the accumulation of PINK1, Parkin and other mitophagy proteins at baseline. The further accumulation of endogenous LC3BII, p62 and PINK1 in the presence of E64d and pepstatin A in severe asthmatic fibroblasts reinforced their enhanced mitophagy flux. Significantly reduced mitochondrial membrane potential and metabolic activity were also demonstrated at baseline confirming the impairment in mitochondrial function in severe asthmatic fibroblasts. Interestingly, these fibroblasts displayed neither an apoptotic nor senescent phenotype but a pro-fibrotic phenotype with an adaptive survival mechanism triggered by increased AMPKα phosphorylation and mitochondrial biogenesis.

Conclusions

Our results demonstrated a role for mitophagy in the pathogenesis of severe asthma where the enhanced turnover of damaged mitochondria may contribute to fibrosis in severe asthma by promoting the persistence and pro-fibrotic phenotype of fibroblasts.

CASCADE: a phase 2, randomized, double-blind, placebo-controlled, parallel-group trial to evaluate the effect of tezepelumab on airway inflammation in patients with uncontrolled asthma

BACKGROUND

Patients with severe, uncontrolled asthma, particularly those with a non-eosinophilic phenotype, have a great unmet need for new treatments that act on a broad range of inflammatory pathways in the airway. Tezepelumab is a human monoclonal antibody that blocks the activity of thymic stromal lymphopoietin, an epithelial cytokine. In the PATHWAY phase 2b study (NCT02054130), tezepelumab reduced exacerbations by up to 71% in adults with severe, uncontrolled asthma, irrespective of baseline eosinophilic inflammatory status. This article reports the design and objectives of the phase 2 CASCADE study.

METHODS

CASCADE is an ongoing exploratory, phase 2, randomized, double-blind, placebo-controlled, parallel-group study aiming to assess the anti-inflammatory effects of tezepelumab 210 mg administered subcutaneously every 4 weeks for 28 weeks in adults aged 18-75 years with uncontrolled, moderate-to-severe asthma. The primary endpoint is the change from baseline to week 28 in airway submucosal inflammatory cells (eosinophils, neutrophils, T cells and mast cells) from bronchoscopic biopsies. Epithelial molecular phenotyping, comprising the three-gene-mean technique, will be used to assess participants' type 2 (T2) status to enable evaluation of the anti-inflammatory effect of tezepelumab across the continuum of T2 activation. Other exploratory analyses include assessments of the impact of tezepelumab on airway remodelling, including reticular basement membrane thickening and airway epithelial integrity. At the onset of the COVID-19 pandemic, the protocol was amended to address the possibility that site visits would be limited. The amendment allowed for: at-home dosing of study drug by a healthcare professional, extension of the treatment period by up to 6 months so patients are able to attend an onsite visit to undergo the end-of-treatment bronchoscopy, and replacement of final follow-up visits with a virtual or telephone visit.

DISCUSSION

CASCADE aims to determine the mechanisms by which tezepelumab improves clinical asthma outcomes by evaluating the effect of tezepelumab on airway inflammatory cells and remodelling in patients with moderate-to-severe, uncontrolled asthma. An important aspect of this study is the evaluation of the anti-inflammatory effect of tezepelumab across patients with differing levels of eosinophilic and T2 inflammation.

TRIAL REGISTRATION

NCT03688074 (ClinicalTrials.gov). Registered 28 September 2018.