The pivotal role of airway smooth muscle in asthma pathophysiology. J Allergy (Cairo). 2011;2011:742710. [PMID: 22220184 PMCID: PMC3246780 DOI: 10.1155/2011/742710]

Pulmonary adaptation to repeated poly(I:C) exposure is impaired in asthmatic mice: an observational study

BACKGROUND

While asthma exacerbations remain a major challenge in patient management, few animal models exist to explore the underlying mechanisms. Here, we established an animal model of asthma that can be used to study pathophysiological mechanisms and therapeutic strategies on asthma exacerbation.

METHODS

Female BALB/c mice were sensitized and exposed to PBS or Dermatophagoides pteronyssinus (DerP) extract for 11 weeks. Asthmatic phenotype was assessed through lung inflammation, bronchial hyperresponsiveness and bronchial smooth muscle remodeling. Asthmatic and control mice were exposed once or three times to poly(I:C) to simulate virus-induced inflammation.

RESULTS

Fourteen days after exposure to DerP, asthmatic mice showed resolution of inflammation with sustained bronchial hyperresponsiveness and bronchial smooth muscle remodeling compared to control. At this stage, when mice were subjected to a single exposure to poly(I:C), control and asthmatic mice were characterized by a significant increase in neutrophilic inflammation and bronchial hyperresponsiveness. When mice were repeatedly exposed to poly(I:C), control mice showed a significant decrease in neutrophilic inflammation and bronchial hyperresponsiveness, while asthmatic mice experienced worsening of these outcomes.

CONCLUSIONS

This observational study report an asthmatic mouse model that can undergo exacerbation after repeated exposure to poly(I:C). Our findings on pulmonary adaptation in control mice may also pave the way for further research into the mechanism of adaptation that may be impaired in asthma and raise the question of whether asthma exacerbation may be a loss of adaptation.

A review of the safety profile, antioxidant, anti-inflammatory, and bronchorelaxant activities of Waltheria indica Linn (Malvaceae): A potential antiasthmatic phytomedicine

Introduction

Waltheria indica Linn (Malvaceae) is a widely distributed plant in West Africa. It is commonly used in Burkina Faso to treat inflammation-related diseases, including asthma. Previous reviews have focused on the ethnobotanical, traditional uses, phytochemistry, and pharmacological properties of Waltheria indica. This report aims to compile the biological and pharmacological activities that highlight the anti-asthmatic properties of Waltheria indica L. (W. indica).

Method

Electronic databases, such as PubMed, Scopus, Hinari, SciFinder, Google Scholar, and ScienceDirect, were used to gather data on Watheria indica. Data on the toxicological, anti-inflammatory, antioxidant, and bronchorelaxant effects of W. indica were collected.

Results

Twenty-three studies describing the biological and pharmacological activities relevant to assessing the anti-asthmatic properties of W. indica were found. Nine articles investigated the anti-inflammatory effects, and three manuscripts were found to have bronchorelaxant activity. Five publications reported the antioxidant activity of the plant extracts. Research on the extracts revealed a tolerable safety profile in rats and mice with an LD50 ranging from 300 to 5000 mg/kg body weight, depending on the parts of the plant used. Phenolic compounds, particularly flavonoids, alkaloids, and saponins, were found to be responsible for the activities involved in the assessment of anti-asthmatic properties.

Conclusion

The results of this review suggest that W. indica could be a valuable resource for the treatment of asthma and other respiratory diseases. However, further chemical and pharmacological investigations are needed to understand its mechanism of action in treating asthma.

A high-throughput 3D cantilever array to model airway smooth muscle hypercontractility in asthma

Asthma is often characterized by tissue-level mechanical phenotypes that include remodeling of the airway and an increase in airway tightening, driven by the underlying smooth muscle. Existing therapies only provide symptom relief and do not improve the baseline narrowing of the airway or halt progression of the disease. To investigate such targeted therapeutics, there is a need for models that can recapitulate the 3D environment present in this tissue, provide phenotypic readouts of contractility, and be easily integrated into existing assay plate designs and laboratory automation used in drug discovery campaigns. To address this, we have developed DEFLCT, a high-throughput plate insert that can be paired with standard labware to easily generate high quantities of microscale tissues in vitro for screening applications. Using this platform, we exposed primary human airway smooth muscle cell-derived microtissues to a panel of six inflammatory cytokines present in the asthmatic niche, identifying TGF-β1 and IL-13 as inducers of a hypercontractile phenotype. RNAseq analysis further demonstrated enrichment of contractile and remodeling-relevant pathways in TGF-β1 and IL-13 treated tissues as well as pathways generally associated with asthma. Screening of 78 kinase inhibitors on TGF-β1 treated tissues suggests that inhibition of protein kinase C and mTOR/Akt signaling can prevent this hypercontractile phenotype from emerging, while direct inhibition of myosin light chain kinase does not. Taken together, these data establish a disease-relevant 3D tissue model for the asthmatic airway, which combines niche specific inflammatory cues and complex mechanical readouts that can be utilized in drug discovery efforts.

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.

New insights into the pathophysiology and therapeutic targets of asthma and comorbid chronic rhinosinusitis with or without nasal polyposis

Asthma and chronic rhinosinusitis with nasal polyps (CRSwNP) or without (CRSsNP) are chronic respiratory diseases. These two disorders often co-exist based on common anatomical, immunological, histopathological, and pathophysiological basis. Usually, asthma with comorbid CRSwNP is driven by type 2 (T2) inflammation which predisposes to more severe, often intractable, disease. In the past two decades, innovative technologies and detection techniques in combination with newly introduced targeted therapies helped shape our understanding of the immunological pathways underlying inflammatory airway diseases and to further identify several distinct clinical and inflammatory subsets to enhance the development of more effective personalized treatments. Presently, a number of targeted biologics has shown clinical efficacy in patients with refractory T2 airway inflammation, including anti-IgE (omalizumab), anti-IL-5 (mepolizumab, reslizumab)/anti-IL5R (benralizumab), anti-IL-4R-α (anti-IL-4/IL-13, dupilumab), and anti-TSLP (tezepelumab). In non-type-2 endotypes, no targeted biologics have consistently shown clinical efficacy so far. Presently, multiple therapeutical targets are being explored including cytokines, membrane molecules and intracellular signalling pathways to further expand current treatment options for severe asthma with and without comorbid CRSwNP. In this review, we discuss existing biologics, those under development and share some views on new horizons.

The Complex Journey of the Calcium Regulation Downstream of TAS2R Activation

Bitter taste receptors (TAS2Rs) have recently arisen as a potential drug target for asthma due to their localization in airway cells. These receptors are expressed in all cell types of the respiratory system comprising epithelial, smooth muscle and immune cells; however, the expression pattern of the subtypes is different in each cell type and, accordingly, so is their role, for example, anti-inflammatory or bronchodilator. The most challenging aspect in studying TAS2Rs has been the identification of the downstream signaling cascades. Indeed, TAS2R activation leads to canonical IP3-dependent calcium release from the ER, but, alongside, there are other mechanisms that differ according to the histological localization. In this review, we summarize the current knowledge on the cytosolic calcium modulation downstream of TAS2R activation in the epithelial, smooth muscle and immune cells of the airway system.

Airway smooth muscle function in asthma

Known to have affected around 340 million people across the world in 2018, asthma is a prevalent chronic inflammatory disease of the airways. The symptoms such as wheezing, dyspnea, chest tightness, and cough reflect episodes of reversible airway obstruction. Asthma is a heterogeneous disease that varies in clinical presentation, severity, and pathobiology, but consistently features airway hyperresponsiveness (AHR)—excessive airway narrowing due to an exaggerated response of the airways to various stimuli. Airway smooth muscle (ASM) is the major effector of exaggerated airway narrowing and AHR and many factors may contribute to its altered function in asthma. These include genetic predispositions, early life exposure to viruses, pollutants and allergens that lead to chronic exposure to inflammatory cells and mediators, altered innervation, airway structural cell remodeling, and airway mechanical stress. Early studies aiming to address the dysfunctional nature of ASM in the etiology and pathogenesis of asthma have been inconclusive due to the methodological limitations in assessing the intrapulmonary airways, the site of asthma. The study of the trachealis, although convenient, has been misleading as it has shown no alterations in asthma and it is not as exposed to inflammatory cells as intrapulmonary ASM. Furthermore, the cartilage rings offer protection against stress and strain of repeated contractions. More recent strategies that allow for the isolation of viable intrapulmonary ASM tissue reveal significant mechanical differences between asthmatic and non-asthmatic tissues. This review will thus summarize the latest techniques used to study ASM mechanics within its environment and in isolation, identify the potential causes of the discrepancy between the ASM of the extra- and intrapulmonary airways, and address future directions that may lead to an improved understanding of ASM hypercontractility in asthma.

Antispasmodic activity of the ethanol extract of Citrullus lanatus seeds: Justifying ethnomedicinal use in Pakistan to treat asthma and diarrhea

ETHNOPHARMACOLOGICAL RELEVANCE

Citrullus lanatus (Thunb.) belongs to the ground family, Cucurbitaceae, known for edible fruit. Besides nutritional benefits, the traditional herbal practitioners in Pakistan and India used their seeds to treat gastrointestinal, respiratory, and urinary disorders. In Northern Sudan, its seeds are often used as a laxative. Its root is laxative and emetic at a high dose. Its seeds are also used to treat bedwetting and urinary tract obstruction.

AIM OF THE STUDY

This study aimed to elucidate the multi-target mechanisms of Citrullus lanatus seeds to treat asthma and diarrhea. The pharmacological experiments were designed and conducted, along with the pharmacology network and molecular docking predictions, to verify the seeds biopotency for antispasmodic and bronchodilator properties.

METHODS

LC ESI-MS/MS were performed to identify the potentially active compounds in hydroethanolic extract of Citrullus lanatus seeds, then to quantify them by HPLC. The quantified bioactive compounds of Citrullus lanatus, i.e., stigmasterol, quinic acid, malic acid, epicatechin, caffeic acid, rutin, p-coumaric acid, quercetin, ferulic acid, scopoletin, apigenin, and kaempferol were subjected to in silico studies for molecular docking. The hydroethanolic extract of Citrullus lanatus seeds was examined on isolated rabbit tissue, i.e., jejunum, trachea, and urinary bladder. The antiperistalsis, antidiarrheal and antisecretory studies were also performed in animal models.

RESULTS

In silico studies revealed that bioactive compounds of C. lanatus seeds interfere with asthma and diarrhea-associated target genes, which are a member of calcium mediate signaling, regulation of cytosolic calcium concentration, smooth muscle contraction, and inflammatory responses. It was also found that rutin, quercetin, kaempferol, and scopoletin were stronger binding to voltage-gated calcium channels, calcium/calmodulin-dependent protein kinase, myosin light chain kinase, and phosphoinositide phospholipase C, thus, exerting calcium channel blocker activity. The hydroethanolic extract of C. lanatus seeds exerted a concentration-dependent relaxant response for the spasmolytic response on isolated jejunum and trachea preparations and caused relaxation of spastic contraction of K⁺ (80 mM). Furthermore, it caused a non-parallel rightward shift with suppression of calcium concentration-response curves. In animal models, the Cl.EtOH showed antiperistalsis, antidiarrheal and antisecretory response.

CONCLUSION

Thus, we confirm Citrullus lanatus seeds have some medicinal effects by regulating the contractile response through target proteins of calcium mediates signaling and can be a promising component in the medical treatment for asthma and diarrhea.

Role of Obesity in Inflammation and Remodeling of Asthmatic Airway

Obesity is considered as an important risk factor for the onset of asthma and plays a key role in enhancing the disease's severity. Obese asthmatic individuals represent a distinct phenotype of asthma that is associated with additional symptoms, more severe exacerbation, decreased response to standard medication, and poor quality of life. Obesity impairs the function of the lung airway in asthmatic individuals, leading to increased inflammation and severe remodeling of the bronchus; however, the molecular events that trigger such changes are not completely understood. In this manuscript, we review the current findings from studies that focused on understanding the role of obesity in modulating the functions of airway cells, including lung immune cells, epithelial cells, smooth muscle cells, and fibroblasts, leading to airway inflammation and remodeling. Finally, the review sheds light on the current knowledge of different therapeutic approaches for treating obese asthmatic individuals. Given the fact that the prevalence of asthma and obesity has been increasing rapidly in recent years, it is necessary to understand the molecular mechanisms that play a role in the disease pathophysiology of obese asthmatic individuals for developing novel therapies.

Gastric motility and pulmonary function in children with functional abdominal pain disorders and asthma: A pathophysiological study

Background

An association has been shown between functional abdominal pain disorders (FAPDs) and asthma. However, the exact reason for this association is obscured. The main objective of this study is to identify the possible underlying pathophysiological mechanisms for the association between FAPDs and asthma using gastric motility and lung function tests.

Methods

This was a cross-sectional comparative study that consisted of four study groups. Twenty-four children (age 7–12 years) each were recruited for four study groups; asthma only, FAPDs only, both asthma and FAPDs, and healthy controls. Asthma was diagnosed using the history and bronchodilator reversibility test. The diagnosis of FAPDs was made using Rome IV criteria. All subjects underwent ultrasound assessment of gastric motility and pulmonary function assessment by spirometry, using validated techniques.

Results

All gastric motility parameters, gastric emptying rate, amplitude of antral contraction, and antral motility index, were significantly impaired in children with FAPDs only, children with asthma only, and children with both asthma & FAPDs, compared to controls (p<0.05). Pulmonary function parameters indicating airway obstruction (FEV₁/FVC ratio, peak expiratory flow rate, FEF25-75%) were not impaired in children with FAPDs only compared to controls (p>0.05), but significantly impaired in children with asthma and children with both disorders. Antral motility index correlated with the FEV₁/FVC ratio (r = 0.60, p = 0.002) and FEF25%-75% (r = 0.49, p = 0.01) in children with both asthma and FAPDs.

Conclusions

Gastric motor functions were significantly impaired in children with asthma, children with FAPDs, and children with both disorders. Motility index, measuring overall gastric motor activity, showed a significant positive correlation with lung function parameters that measure airflow limitation. Therefore, these diseases might arise as a result of primary disturbance of smooth muscle activity in the airways and gastrointestinal wall, which could be a possible pathophysiological mechanism for this association between asthma and FAPDs.

Molecular pathways involved in COVID-19 and potential pathway-based therapeutic targets

Deciphering the molecular downstream consequences of severe acute respiratory syndrome coronavirus (SARS-CoV)- 2 infection is important for a greater understanding of the disease and treatment planning. Furthermore, greater understanding of the underlying mechanisms of diagnostic and therapeutic strategies can help in the development of vaccines and drugs against COVID-19. At present, the molecular mechanisms of SARS-CoV-2 in the host cells are not sufficiently comprehended. Some of the mechanisms are proposed considering the existing similarities between SARS-CoV-2 and the other members of the β-CoVs, and others are explained based on studies advanced in the structure and function of SARS-CoV-2. In this review, we endeavored to map the possible mechanisms of the host response following SARS-CoV-2 infection and surveyed current research conducted by in vitro, in vivo and human observations, as well as existing suggestions. We addressed the specific signaling events that can cause cytokine storm and demonstrated three forms of cell death signaling following virus infection, including apoptosis, pyroptosis, and necroptosis. Given the elicited signaling pathways, we introduced possible pathway-based therapeutic targets; ADAM17 was especially highlighted as one of the most important elements of several signaling pathways involved in the immunopathogenesis of COVID-19. We also provided the possible drug candidates against these targets. Moreover, the cytokine-cytokine receptor interaction pathway was found as one of the important cross-talk pathways through a pathway-pathway interaction analysis for SARS-CoV-2 infection.

The Impact of Monoclonal Antibodies on Airway Smooth Muscle Contractility in Asthma: A Systematic Review

Airway hyperresponsiveness (AHR) represents a central pathophysiological hallmark of asthma, with airway smooth muscle (ASM) being the effector tissue implicated in the onset of AHR. ASM also exerts pro-inflammatory and immunomodulatory actions, by secreting a wide range of cytokines and chemokines. In asthma pathogenesis, the overexpression of several type 2 inflammatory mediators including IgE, IL-4, IL-5, IL-13, and TSLP has been associated with ASM hyperreactivity, all of which can be targeted by humanized monoclonal antibodies (mAbs). Therefore, the aim of this review was to systematically assess evidence across the literature on mAbs for the treatment of asthma with respect to their impact on the ASM contractile tone. Omalizumab, mepolizumab, benralizumab, dupilumab, and tezepelumab were found to be effective in modulating the contractility of the ASM and preventing the AHR, but no available studies concerning the impact of reslizumab on the ASM were identified from the literature search. Omalizumab, dupilumab, and tezepelumab can directly modulate the ASM in asthma, by specifically blocking the interaction between IgE, IL-4, and TSLP, and their receptors are located on the surface of ASM cells. Conversely, mepolizumab and benralizumab have prevalently indirect impacts against AHR by targeting eosinophils and other immunomodulatory effector cells promoting inflammatory processes. AHR has been suggested as the main treatable trait towards precision medicine in patients suffering from eosinophilic asthma, therefore, well-designed head-to-head trials are needed to compare the efficacy of those mAbs that directly target ASM contractility specifically against the AHR in severe asthma, namely omalizumab, dupilumab, and tezepelumab.

Adiponectin and Asthma: Knowns, Unknowns and Controversies

Adiponectin is an adipokine associated with the healthy obese phenotype. Adiponectin increases insulin sensitivity and has cardio and vascular protection actions. Studies related to adiponectin, a modulator of the innate and acquired immunity response, have suggested a role of this molecule in asthma. Studies based on various asthma animal models and on the key cells involved in the allergic response have provided important insights about this relation. Some of them indicated protection and others reversed the balance towards negative effects. Many of them described the cellular pathways activated by adiponectin, which are potentially beneficial for asthma prevention or for reduction in the risk of exacerbations. However, conclusive proofs about their efficiency still need to be provided. In this article, we will, briefly, present the general actions of adiponectin and the epidemiological studies supporting the relation with asthma. The main focus of the current review is on the mechanisms of adiponectin and the impact on the pathobiology of asthma. From this perspective, we will provide arguments for and against the positive influence of this molecule in asthma, also indicating the controversies and sketching out the potential directions of research to complete the picture.

Asthmatic Eosinophils Promote Contractility and Migration of Airway Smooth Muscle Cells and Pulmonary Fibroblasts In Vitro

Enhanced contractility and migration of airway smooth muscle cells (ASMC) and pulmonary fibroblasts (PF) are part of airway remodeling in asthma. Eosinophils are the central inflammatory cells that participate in airway inflammation. However, the role of asthmatic eosinophils in ASMC and PF contractility, migration, and differentiation to contractile phenotype has not yet been precisely described. A total of 38 individuals were included in this study: 13 steroid-free non-severe allergic asthma (AA) patients, 11 severe non-allergic eosinophilic asthma (SNEA) patients, and 14 healthy subjects (HS). For AA patients and HS groups, a bronchial allergen challenge with D. pteronyssinus was performed. Individual combined cell cultures were prepared from isolated peripheral blood eosinophils and immortalized ASMC or commercial PF cell lines separately. The migration of ASMC and PF was evaluated using wound healing assay and contractility using collagen gel assay. Gene expression of contractile apparatus proteins, COL1A1, COL5A1, and FN, in ASMC and PF was evaluated using qRT-PCR. We found that contractility and migration of ASMC and PF significantly increased after incubation with asthmatic eosinophils compared to HS eosinophils, p < 0.05, and SNEA eosinophils demonstrated the highest effect on contractility of ASMC and migration of both cell lines, p < 0.05. AA and SNEA eosinophils significantly increased gene expression of contractile apparatus proteins, COL1A1 and FN, in both cell lines, p < 0.05. Furthermore, the allergen-activated AA eosinophils significantly increased the contractility of ASMC, and migration and gene expression in ASMC and PF, p < 0.05. Thus, asthmatic eosinophils change ASMC and PF behavior by increasing their contractility and migration, contributing to airway remodeling.

The Impact of Endoplasmic Reticulum-Associated Protein Modifications, Folding and Degradation on Lung Structure and Function

The accumulation of unfolded/misfolded proteins in the endoplasmic reticulum (ER) causes ER stress and induces the unfolded protein response (UPR) and other mechanisms to restore ER homeostasis, including translational shutdown, increased targeting of mRNAs for degradation by the IRE1-dependent decay pathway, selective translation of proteins that contribute to the protein folding capacity of the ER, and activation of the ER-associated degradation machinery. When ER stress is excessive or prolonged and these mechanisms fail to restore proteostasis, the UPR triggers the cell to undergo apoptosis. This review also examines the overlooked role of post-translational modifications and their roles in protein processing and effects on ER stress and the UPR. Finally, these effects are examined in the context of lung structure, function, and disease.

Proteomic profiling of biomarkers by MALDI-TOF mass spectrometry for the diagnosis of tracheobronchial stenosis after tracheobronchial tuberculosis

Tracheobronchial tuberculosis (TB) leads to airway stenosis, irreversible airway damage and even death. The present study aimed to identify biomarkers for the diagnosis of tracheobronchial stenosis (TBS) secondary to tracheobronchial TB. A cohort was recruited, including patients with TBS after tracheobronchial TB, TBS after tracheal intubation or tracheotomy (TIT) and no stenosis of early-stage lung cancer,. Proteomic profiling was performed to gain insight into the mechanisms of the pathological processes. Differentially expressed proteins in the serum and bronchial alveolar lavage fluid (BALF) from patients were detected by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Subsequently, ELISA was performed to validate the changes of protein levels in an additional cohort. MALDI-TOF MS revealed that 8 peptides in the serum, including myeloid-associated differentiation marker, keratin type I cytoskeletal 18, fibrinogen α-chain, angiotensinogen (AGT), apolipoprotein A-I (APOAI), clusterin and two uncharacterized peptides, and nine peptides in BALF, including argininosuccinate lyase, APOAI, AGT and five uncharacterized peptides, were differentially expressed (molecular-weight range, 1,000-10,000 Da) in the TB group compared with the TIT group. The ELISA results indicated that the changes in the protein levels had a similar trend as those identified by proteomic profiling. In conclusion, the present study identified proteins that may serve as potential biomarkers and provide novel insight into the molecular mechanisms underlying TBS after tracheobronchial TB.

Regulatory Effects of Nur77 on Airway Remodeling and ASMC Proliferation in House Dust Mite-Induced Asthma

Airway remodeling played a vital role in the development of asthma, and airway smooth muscle (ASM) mass was its hallmark. However, few strategies targeting ASM remodeling were developed in treating asthma. Nur77 was the transcription factor nuclear receptor involved in the pathogenesis of several lung diseases. Nur77 distribution and expression were determined in an HDM-mediated allergic asthma model. Its effect on airway hyperresponsiveness (AHR), chronic inflammation, and ASM remodeling in asthmatic mice was evaluated using a lentivirus-mediated shRNA. Possible mechanisms were explored by examining Nur77 actions and its underlying pathways in primary human AMC cells (ASMCs). In this study, we reported that Nur77 expression was mainly distributed along ASM and increased in lungs of HDM-challenged mice. Nur77 depletion by lentivirus-mediated shRNA ameliorated AHR, chronic inflammation, goblet cell hyperplasia, and airway remodeling in the asthmatic mouse model. By means of primary human ASMC, we discovered that Nur77 upregulation by HDM stimulation promoted cell proliferation and ROS production, as well as reduced antioxidant gene expression. These alterations might associate with MFN2/MAPK/AKT pathways. These findings broadened our understanding of airway remodeling and ASMC proliferation, which might provide a novel therapeutic target for asthma patients.

Airway mechanical compression: its role in asthma pathogenesis and progression

The lung is a mechanically active organ, but uncontrolled or excessive mechanical forces disrupt normal lung function and can contribute to the development of disease. In asthma, bronchoconstriction leads to airway narrowing and airway wall buckling. A growing body of evidence suggests that pathological mechanical forces induced by airway buckling alone can perpetuate disease processes in asthma. Here, we review the data obtained from a variety of experimental models, including in vitro, ex vivo and in vivo approaches, which have been used to study the impact of mechanical forces in asthma pathogenesis. We review the evidence showing that mechanical compression alters the biological and biophysical properties of the airway epithelium, including activation of the epidermal growth factor receptor pathway, overproduction of asthma-associated mediators, goblet cell hyperplasia, and a phase transition of epithelium from a static jammed phase to a mobile unjammed phase. We also define questions regarding the impact of mechanical forces on the pathology of asthma, with a focus on known triggers of asthma exacerbations such as viral infection.

Environmental and Endogenous Acids Can Trigger Allergic-Type Airway Reactions

Inflammatory allergic and nonallergic respiratory disorders are spreading worldwide and often coexist. The root cause is not clear. This review demonstrates that, from a biochemical point of view, it is ascribable to protons (H+) released into cells by exogenous and endogenous acids. The hypothesis of acids as the common cause stems from two considerations: (a) it has long been known that exogenous acids present in air pollutants can induce the irritation of epithelial surfaces, particularly the airways, inflammation, and bronchospasm; (b) according to recent articles, endogenous acids, generated in cells by phospholipases, play a key role in the biochemical mechanisms of initiation and progression of allergic-type reactions. Therefore, the intracellular acidification and consequent Ca2+ increase, induced by protons generated by either acid pollutants or endogenous phospholipases, may constitute the basic mechanism of the multimorbidity of these disorders, and environmental acidity may contribute to their spread.

MiRNA-620 promotes TGF-β1-induced proliferation of airway smooth muscle cell through controlling PTEN/AKT signaling pathway

Asthma is an inflammatory syndrome characterized by airway hyperresponsiveness, bronchial inflammation, and airway remodeling. The hypertrophy and hyperplasia of airway smooth muscle cells (ASMCs) are hallmarks of bronchial remodeling in asthma. In this study, the regulatory effects of microRNA-620 (miR-620) on ASMC proliferation and apoptosis in response to transforming growth factor β1 (TGF-β1) stimulation was investigated. The expression of miR-620 was significantly upregulated in TGF-β1-treated ASMCs compared with vehicle-treated cells. Downregulation of miR-620 suppressed the proliferation and increased apoptosis in TGF-β1-stimulated ASMCs. Phosphatase and tensin homolog (PTEN) was predicted and confirmed as a downstream target of miR-620. PTEN was upregulated in miR-620-inhibitor transfected ASMCs, but decreased in cells delivered with miR-620 mimics. Moreover, knocking down miR-620 alone efficiently reduced the phosphorylation of protein kinase B (AKT), decreased TGF-β1-induced proliferation and promoted apoptosis in ASMCs, whereas downregulation of PTEN in miR-620 inhibitor-transfected cells restored the activation of AKT, increased TGF-β1-triggered proliferation, and partially inhibited ASMC apoptosis. Taken together, the present study provided evidence that miR-620 increased TGF-β1-mediated proliferation and suppressed apoptosis in ASMCs via the regulation of PTEN and AKT expression. These findings suggest that miR-620/PTEN/AKT axis may be considered as a therapeutic target for asthma treatment.

Dabigatran ameliorates airway smooth muscle remodeling in asthma by modulating Yes-associated protein

Accumulating evidence indicates that thrombin, the major effector of the coagulation cascade, plays an important role in the pathogenesis of asthma. Interestingly, dabigatran, a drug used in clinical anticoagulation, directly inhibits thrombin activity. The aim of this study was to investigate the effects and mechanisms of dabigatran on airway smooth muscle remodeling in vivo and in vitro. Here, we found that dabigatran attenuated inflammatory pathology, mucus production, and collagen deposition in the lungs of asthmatic mice. Additionally, dabigatran suppressed Yes‐associated protein (YAP) activation in airway smooth muscle of asthmatic mice. In human airway smooth muscle cells (HASMCs), dabigatran not only alleviated thrombin‐induced proliferation, migration and up‐regulation of collagen I, α‐SMA, CTGF and cyclin D1, but also inhibited thrombin‐induced YAP activation, while YAP activation mediated thrombin‐induced HASMCs remodeling. Mechanistically, thrombin promoted actin stress fibre polymerization through the PAR1/RhoA/ROCK/MLC2 axis to activate YAP and then interacted with SMAD2 in the nucleus to induce downstream target genes, ultimately aggravating HASMCs remodeling. Our study provides experimental evidence that dabigatran ameliorates airway smooth muscle remodeling in asthma by inhibiting YAP signalling, and dabigatran may have therapeutic potential for the treatment of asthma.

Asthmatic Bronchial Smooth Muscle Increases CCL5-Dependent Monocyte Migration in Response to Rhinovirus-Infected Epithelium

Asthma exacerbations, a major concern in therapeutic strategies, are most commonly triggered by viral respiratory infections, particularly with human rhinovirus (HRV). Infection of bronchial epithelial (BE) cells by HRV triggers inflammation, notably monocyte recruitment. The increase of bronchial smooth muscle (BSM) mass in asthma, a hallmark of bronchial remodeling, is associated with the annual rate of exacerbations. The aim of the present study was to assess whether or not BSM could increase monocyte migration induced by HRV-infected BE. We used an advanced in vitro model of co-culture of human BE cells in air-liquid interface with human BSM cells from control and asthmatic patients. Inflammation triggered by HRV infection (HRV-16, MOI 0.1, 1 h) was assessed at 24 h with transcriptomic analysis and multiplex ELISA. In vitro CD14⁺ monocyte migration was evaluated with modified Boyden chamber. Results showed that HRV-induced monocyte migration was substantially increased in the co-culture model with asthmatic BSM, compared with control BSM. Furthermore, the well-known monocyte migration chemokine, CCL2, was not involved in this increased migration. However, we demonstrated that CCL5 was further increased in the asthmatic BSM co-culture and that anti-CCL5 blocking antibody significantly decreased monocyte migration induced by HRV-infected BE. Taken together, our findings highlight a new role of BSM cells in HRV-induced inflammation and provide new insights in mucosal immunology which may open new opportunities for prevention and/or treatment of asthma exacerbation.

Crosstalk Between Signaling Pathways Involved in the Regulation of Airway Smooth Muscle Cell Hyperplasia

Increased ASM mass, primarily due to ASM hyperplasia, has been recognized as a hallmark of airway remodeling in asthma. Increased ASM mass is the major contributor to the airway narrowing, thus worsening the bronchoconstriction in response to stimuli. Inflammatory mediators and growth factors released during inflammation induce increased ASM mass surrounding airway wall via increased ASM proliferation, diminished ASM apoptosis and increased ASM migration. Several major pathways, such as MAPKs, PI3K/AKT, JAK2/STAT3 and Rho kinase, have been reported to regulate these cellular activities in ASM and were reported to be interrelated at certain points. This article aims to provide an overview of the signaling pathways/molecules involved in ASM hyperplasia as well as the mapping of the interplay/crosstalk between these major pathways in mediating ASM hyperplasia. A more comprehensive understanding of the complexity of cellular signaling in ASM cells will enable more specific and safer drug development in the control of asthma.

Modeling the pasture-associated severe equine asthma bronchoalveolar lavage fluid proteome identifies molecular events mediating neutrophilic airway inflammation

Background: Pasture-associated severe equine asthma is a warm season, environmentally-induced respiratory disease characterized by reversible airway obstruction, persistent and non-specific airway hyper-responsiveness, and chronic neutrophilic airway inflammation. During seasonal exacerbation, signs vary from mild to life-threatening episodes of wheezing, coughing, and chronic debilitating labored breathing.

Purpose: In human asthma, neutrophilic airway inflammation is associated with more severe and steroid-refractory asthma phenotypes, highlighting a need to decipher the mechanistic basis of this disease characteristic. We hypothesize that the collective biological activities of proteins in bronchoalveolar lavage fluid (BALF) of horses with pasture-associated severe asthma predict changes in neutrophil functions that contribute to airway neutrophilic inflammation.

Methods: Using shotgun proteomics, we identified 1,003 unique proteins in cell-free BALF from six horses experiencing asthma exacerbation and six control herdmates. Contributions of each protein to ten neutrophil functions were modeled using manual biocuration to determine each protein’s net effect on the respective neutrophil functions.

Results: A total of 417 proteins were unique to asthmatic horses, 472 proteins were unique to control horses (p<0.05), and 114 proteins were common in both groups. Proteins whose biological activities are responsible for increasing neutrophil migration, chemotaxis, cell spreading, transmigration, and infiltration, which would collectively bring neutrophils to airways, were over-represented in the BALF of asthmatic relative to control horses. By contrast, proteins whose biological activities support neutrophil activation, adhesion, phagocytosis, respiratory burst, and apoptosis, which would collectively shorten neutrophil lifespan, were under-represented in BALF of asthmatic relative to control horses. Interaction networks generated using Ingenuity^® Pathways Analysis further support the results of our biocuration.

Conclusion: Congruent with our hypothesis, the collective biological functions represented in differentially expressed proteins of BALF from horses with pasture-associated severe asthma support neutrophilic airway inflammation. This illustrates the utility of systems modeling to organize functional genomics data in a manner that characterizes complex molecular events associated with clinically relevant disease.

The ethanol extract of Involcucrum castaneae ameliorated ovalbumin-induced airway inflammation and smooth muscle thickening in guinea pigs

ETHNOPHARMACOLOGICAL RELEVANCE

Involucrum castaneae(IC)is used in Chinese folk medicine to treat various lung diseases, as well as for its reducing phlegm and anti-inflammatory properties.

AIM OF THE STUDY

The purpose of this experiment is to verify the effect of IC on airway inflammation, responsiveness in ovalbumin (OVA)-induced asthmatic guinea pigs. The main chemical components of IC were also analyzed.

MATERIALS AND METHODS

The potential of the ethanol extract of Involucrum castaneae (EEIC) to protect against OVA-induced allergic airway response in guinea pigs was investigated. The latency of asthma in guinea pigs were recorded after the allergic asthma induced. Enzyme-linked immunosorbent assay (ELISA) was used to measure the levels of immunoglobulin E (IgE), interleukin-5 (IL-5), nerve growth factor (NGF) and interferon-γ (IFN-γ) in asthma allergy. Reverse transcription-PCR (RT-PCR) was used to detect the expression of IL-5 mRNA in asthmatic guinea pig lungs. Paraffin sections of lung tissue were used to analyze pathological changes. The total flavonoid content was determined and the chemical components were analyzed by LC-MS/MS.

RESULTS

It was found that EEIC was able to reduce the number of eosinophil (EOS) in bronchoalveolar lavage fluid (BALF) and peripheral blood (PB) in the guinea pig model of OVA -induced asthma. Meanwhile, it also significantly reduced the levels of inflammation-related factors IgE and IL-5, decreased the expression of IL-5 mRNA in lung tissue, and increased the level of IFN-γ. Pathological examination of paraffin section of lung tissue showed that EEIC can reduce the thickening of bronchial smooth muscle and reduce the infiltration damage of tissues by various inflammatory cells. The presence of flavonoids, terpenoids and phenolic compounds in EEIC might be responsible for these activities.

CONCLUSION

IC alleviated airway inflammation and smooth muscle thickening in guinea pigs with OVA-sensitized allergic asthma. The paper explains the traditional efficacy and material basis of IC and lays a foundation for further development.

TGF-β1 induces airway smooth muscle cell proliferation and remodeling in asthmatic mice by up-regulating miR-181a and suppressing PTEN

Several studies have shown that transforming growth factor β1 (TGF-β1) plays a crucial role in remodeling and proliferation of airway smooth muscle cells (ASMCs). However, its molecular mechanism needs to be further studied. TGF-β1 can up-regulate the level of miR-181a in multiple cells, while miR-181a is expressed in asthma. We asked whether TGF-β1 plays a role in asthma through regulation of miR-181a. For this purpose, ASMCs were stimulated with TGF-β1 and the expression level of miR-181a and extracellular matrix (ECM) protein were measured by quantitative real time polymerase chain reaction (qRT-PCR) and western blotting. The cell proliferation and migration ability of TGF-β1-induced ASMCs were detected by Cell Counting Kit-8 (CCK-8) and transwell method, respectively. Luciferase assay was used to verify whether PTEN is a direct target of miR-181a in ASMCs. miR-181a expression level was increased in TGF-β1-induced ASMCs and miR-181a could inhibit the cell proliferation, migration, and excessive secretion of ECM. The results of the luciferase assay showed that miR-181a plays a role in TGF-β1-induced ASMCs targeting PTEN and the results of western blotting indicated that TGF-β1 could activate Akt/mTOR signaling pathway by up-regulating miR-181a and down-regulating siPTEN. In conclusion, TGF-β1 may induce airway smooth muscle cell proliferation and airway remodeling of asthma by up-regulating miR-181a and suppressing PTEN, and miR-181a inhibitor may function as an inhibitor of ASMCs proliferation through inactivation of the Akt/mTOR pathway.

Association between functional abdominal pain disorders and asthma in adolescents: A cross-sectional study

AIM

To find the association between asthma and different types of functional abdominal pain disorders (FAPDs) among teenagers.

METHOD

A cross-sectional study was conducted among 13 to 15-year-old children from six randomly selected schools in Anuradhapura district of Sri Lanka. Data were collected using translated and validated self-administered questionnaires (Rome III questionnaire, International Study on Asthma and Allergies in Childhood questionnaire, and Pediatric Quality of Life Inventory 4.0) and administered under an examination setting after obtaining parental consent and assent.

RESULTS

Of the 1101 children included in the analysis, 157 (14.3%) had asthma and 101 (9.2%) had at least one FAPDs. Of children with asthma, 19.1% had at least one type of FAPDs. Prevalence rates of functional abdominal pain (FAP) (8.9% vs 3.3% in non-asthmatics), functional dyspepsia (FD) (2.5% vs 0.7%), and abdominal migraine (AM) (3.2% vs 0.4%) were higher in those with asthma (P < 0.05, multiple logistic regression analysis), but not in those with irritable bowel syndrome (4.5% vs 3.1%, P = 0.2). Severe abdominal pain (10.8% vs 4.6%), bloating (16.6% vs 9.6%), nausea (6.4% vs 2.9%), and anorexia (24.2% vs 16.2%) were more prevalent among asthmatics (P < 0.05). Lower gastrointestinal symptoms did not show a significant difference. Scores obtained for health related quality of life (HRQoL) were lower in those with asthma and FAPDs (P < 0.05, unpaired t-test).

CONCLUSION

Asthma is associated with three different types of FAPDs, namely, FD, AM, and FAP. HRQoL is significantly impaired in teenagers with asthma and FAPDs.

Modulatory role of gabapentin against ovalbumin-induced asthma, bronchial and airway inflammation in mice

Allergic asthma is a type of chronic immune-mediated inflammatory lung disorders with constantly increased worldwide prevalence. Gabapentin is an L-type calcium channel blocker used essentially as antiepileptic and recently has been indicated for management of post-operative and neuropathic pains as an anti-inflammatory. The current study was conducted to evaluate the anti-inflammatory and anti-allergic properties of gabapentin in a mouse-model of Ovalbumin-induced allergic asthma. Mice received OVA (10 mg) adsorbed on Al(OH)₃ on days 0 and 7 and were challenged by exposure to nebulized OVA solution (1%) form days 14-16. Asthma induction was associated with significant biochemical, oxidative and inflammatory imbalance. Daily oral gabapentin (50 mg/kg), significantly reduced lung inflammatory cells counts', serum LDH and catalase activities and lung/body weight index. Moreover, gabapentin significantly increased lung GSH concentration and enhanced SOD activity. Lung contents of TNFα, IL-4 and IL-13 significantly declined as well. IL-13; is the major contributor to airway hyper-responsiveness; the charetrestic hallmark of asthma and IL-4; a major chemoattractant cytokine. Lung histopathology significantly improved parallel to the biochemical improvements. In conclusion; Gabapentin's modulatory effect on IL-4, IL-13 and TNFα activities accounts for the observed anti-inflammatory and anti-allergic properties.

Role of microRNA in severe asthma

The various roles of microRNAs (miRNAs) in the epigenetic regulation of human disease are gaining importance as areas of research, and a better understanding of these roles may identify targets for development of novel therapies for severe asthma. MiRNAs, a class of small non-coding RNAs that serve as post-transcriptional gene repressors, are recognized as critical components in regulating tissue homeostasis. Alteration in miRNA expression disrupts homeostasis and is an underlying mechanism for development of chronic respiratory diseases, including asthma. Differential profiles of miRNA expression are involved in inflammation and remodeling pathogenicity via activating airway structural cells and immune cells and inducing cytokine releases. miRNA action leads to asthma progression from mild to severe stages. Here, current knowledge of the heterogeneous roles of miRNAs in severe asthma, including biological mechanisms underlying Th2 and macrophage polarization, type 2 innate lymphoid cell (ILC2) biology regulation, steroid-resistant asthma phenotype, airway smooth muscle (ASM) dysfunction, and impaired anti-viral innate immune, are reviewed.

Caveolin-3 differentially orchestrates cholinergic and serotonergic constriction of murine airways

The mechanisms of controlling airway smooth muscle (ASM) tone are of utmost clinical importance as inappropriate constriction is a hallmark in asthma and chronic obstructive pulmonary disease. Receptors for acetylcholine and serotonin, two relevant mediators in this context, appear to be incorporated in specialized, cholesterol-rich domains of the plasma membrane, termed caveolae due to their invaginated shape. The structural protein caveolin-1 partly accounts for anchoring of these receptors. We here determined the role of the other major caveolar protein, caveolin-3 (cav-3), in orchestrating cholinergic and serotonergic ASM responses, utilizing newly generated cav-3 deficient mice. Cav-3 deficiency fully abrogated serotonin-induced constriction of extrapulmonary airways in organ baths while leaving intrapulmonary airways unaffected, as assessed in precision cut lung slices. The selective expression of cav-3 in tracheal, but not intrapulmonary bronchial epithelial cells, revealed by immunohistochemistry, might explain the differential effects of cav-3 deficiency on serotonergic ASM constriction. The cholinergic response of extrapulmonary airways was not altered, whereas a considerable increase was observed in cav-3^-/- intrapulmonary bronchi. Thus, cav-3 differentially organizes serotonergic and cholinergic signaling in ASM through mechanisms that are specific for airways of certain caliber and anatomical position. This may allow for selective and site-specific intervention in hyperreactive states.

Transforming Growth Factor β1 Function in Airway Remodeling and Hyperresponsiveness. The Missing Link?

The pathogenesis of asthma includes a complex interplay among airway inflammation, hyperresponsiveness, and remodeling. Current evidence suggests that airway structural cells, including bronchial smooth muscle cells, myofibroblasts, fibroblasts, and epithelial cells, mediate all three aspects of asthma pathogenesis. Although studies show a connection between airway remodeling and changes in bronchomotor tone, the relationship between the two remains unclear. Transforming growth factor β1 (TGF-β1), a growth factor elevated in the airway of patients with asthma, plays a role in airway remodeling and in the shortening of various airway structural cells. However, the role of TGF-β1 in mediating airway hyperresponsiveness remains unclear. In this review, we summarize the literature addressing the role of TGF-β1 in airway remodeling and shortening. Through our review, we aim to further elucidate the role of TGF-β1 in asthma pathogenesis and the link between airway remodeling and airway hyperresponsiveness in asthma and to define TGF-β1 as a potential therapeutic target for reducing asthma morbidity and mortality.

IL-17F induces IL-6 via TAK1-NFκB pathway in airway smooth muscle cells

Introduction

Interleukin (IL)‐17F plays a critical role in the pathophysiology of asthma. However, the precise role of IL‐17F in airway smooth muscle cells (ASMCs) and its regulatory mechanisms remain to be defined. Therefore, we sought to investigate the expression of IL‐6 by IL‐17F and the involvement of transforming growth factor β‐activated kinase 1 (TAK1) and nuclear factor (NF)‐κB by in ASMCs.

Methods

ASMCs were cultured in the presence or absence of IL‐17F. The expression of IL‐6 gene and protein was analyzed using real‐time PCR and ELISA, and the activation of TAK1 and NF‐κB was detected by Western blotting. The effect of TAK1 inhibitor 5Z‐7‐oxozeaenol and NF‐κB inhibitor BAY 11‐7082 on the expression of IL‐6 was investigated. Finally, the short interfering RNAs (siRNAs) targeting TAK1 and a subunit of NF‐κB, p65 were transfected into ASMCs.

Results

The expression of IL‐6 gene and protein was significantly induced by IL‐17F. IL‐17F activated TAK1 and NF‐κB in ASMCs. Transfection of siRNAs targeting TAK1 abolished IL‐17F‐induced phosphorylation of p65. Both 5Z‐7‐oxozeaenol and BAY 11‐7082 significantly inhibited IL‐17F‐induced IL‐6 production in a dose‐dependent manner. Similarly, transfection of the cells with siRNAs targeting TAK1 and p65 inhibited the expression of IL‐6.

Conclusions

Collectively, these results provided evidence supporting the potential importance of the Th17‐ASMCs crosstalk via the IL‐17F‐IL‐6 axis in airway inflammation and as a candidate pharmacological target for airway inflammatory diseases such as asthma.

CD38 in the pathogenesis of allergic airway disease: Potential therapeutic targets

CD38 is an ectoenzyme that catalyzes the conversion of β-nicotinamide adenine dinucleotide (β-NAD) to cyclic adenosine diphosphoribose (cADPR) and adenosine diphosphoribose (ADPR) and NADP to nicotinic acid adenine dinucleotide phosphate (NAADP) and adenosine diphosphoribose-2'-phosphate (ADPR-P). The metabolites of NAD and NADP have roles in calcium signaling in different cell types including airway smooth muscle (ASM) cells. In ASM cells, inflammatory cytokines augment CD38 expression and to a greater magnitude in cells from asthmatics, indicating a greater capacity for the generation of cADPR and ADPR in ASM from asthmatics. CD38 deficient mice develop attenuated airway responsiveness to inhaled methacholine following allergen sensitization and challenge compared to wild-type mice indicating its potential role in asthma. Regulation of CD38 expression in ASM cells is achieved by mitogen activated protein kinases, specific isoforms of PI3 kinases, the transcription factors NF-κB and AP-1, and post-transcriptionally by microRNAs. This review will focus on the role of CD38 in intracellular calcium regulation in ASM, contribution to airway inflammation and airway hyperresponsiveness in mouse models of allergic airway inflammation, the transcriptional and post-transcriptional mechanisms of regulation of expression, and outline approaches to inhibit its expression and activity.

Overexpression of soluble ADAM33 promotes a hypercontractile phenotype of the airway smooth muscle cell in rat

A disintegrin and metalloproteinase 33 (ADAM33) has been identified as a susceptibility gene for asthma, but details of the causality are not fully understood. We hypothesize that soluble ADAM33 (sADAM33) overexpression can alter the mechanical behaviors of airway smooth muscle cells (ASMCs) via regulation of the cell's contractile phenotype, and thus contributes to airway hyperresponsiveness (AHR) in asthma. To test this hypothesis, we either overexpressed or knocked down the sADAM33 in rat ASMCs by transfecting the cells with sADAM33 coding sequence or a small interfering RNA (siRNA) that specifically targets the ADAM33 disintegrin domain, and subsequently assessed the cells for stiffness, contractility and traction force, together with the expression level of contractile and proliferative phenotype markers. We also investigated whether these changes were dependent on Rho/ROCK pathway by culturing the ASMCs either in the absence or presence of ROCK inhibitor (H1152). The results showed that the ASMCs with sADAM33 overexpression were stiffer and more contractile, generated greater traction force, exhibited increased expression levels of contractile phenotype markers and markedly enhanced Rho activation. Furthermore these changes were largely attenuated when the cells were cultured in the presence of H-1152. However, the knock-down of ADAM33 seemed insufficient to influence majority of the mechanical behaviors of the ASMCs. Taken together, we demonstrated that sADAM33 overexpression altered the mechanical behaviors of ASMCs in vitro, which was most likely by promoting a hypercontractile phenotype transition of ASMCs through Rho/ROCK pathway. This revelation may establish the previously missing link between ADAM33 expression and AHR, and also provide useful insight for targeting sADAM33 in asthma prevention and therapy.

Stem Cells in Lung Injury and Repair

In this review, we summarize the recent literature on the biology of endogenous stem cells in adult lung injury repair. We focus on in vivo studies in mice with an emphasis on data generated using cell-specific Cre-dependent lineage-tracing systems. These studies provide new information on the identification of lung stem cells, their hierarchical relationships, the plasticity of their behavior in different types of injury, and the molecular signals that control their fates. Although most of this work has been on epithelial hierarchies, we expect that further development of robust genetic tools will foster meaningful investigations into how nonepithelial cell populations are controlled during lung injury repair in adults. The ultimate challenge will be to translate these findings to the pathogenesis and treatment of human lung diseases.

Aberrant DNA Methylation of Phosphodiesterase [corrected] 4D Alters Airway Smooth Muscle Cell Phenotypes

Airway hyperresponsiveness (AHR) is a hallmark feature in asthma characterized by exaggerated airway contractile response to stimuli due to increased airway sensitivity and chronic airway remodeling. We have previously shown that allergen-induced AHR in mice is associated with aberrant DNA methylation in the lung genome, suggesting that AHR could be epigenetically regulated, and these changes might predispose the animals to asthma. Previous studies demonstrated that overexpression of phosphodiesterase 4D (PDE4D) is associated with increased AHR. However, epigenetic regulation of this gene in asthmatic airway smooth muscle cells (ASMCs) has not been examined. In this study, we aimed to examine the relationship between epigenetic regulation of PDE4D and ASMC phenotypes. We identified CpG site-specific hypomethylation at PDE4D promoter in human asthmatic ASMCs. We next used methylated oligonucleotides to introduce CpG site-specific methylation at PDE4D promoter and examined its effect on ASMCs. We showed that PDE4D methylation decreased cell proliferation and migration of asthmatic ASMCs. We further elucidated that methylated PDE4D decreased PDE4D expression in asthmatic ASMCs, increased cAMP level, and inhibited the aberrant increase in Ca(2+) level. Moreover, PDE4D methylation reduced the phosphorylation level of downstream effectors of Ca(2+) signaling, including myosin light chain kinase and p38. Taken together, our findings demonstrate that gene-specific epigenetic changes may predispose ASMCs to asthma through alterations in cell phenotypes. Modulation of ASMC phenotypes by methylated PDE4D oligonucleotides can reverse the aberrant ASMC functions to normal phenotypes. This has provided new insight to the development of novel therapeutic options for this debilitative disease.

MicroRNA Mediated Chemokine Responses in Human Airway Smooth Muscle Cells

Airway smooth muscle (ASM) cells play a critical role in the pathophysiology of asthma due to their hypercontractility and their ability to proliferate and secrete inflammatory mediators. microRNAs (miRNAs) are gene regulators that control many signaling pathways and thus serve as potential therapeutic alternatives for many diseases. We have previously shown that miR-708 and miR-140-3p regulate the MAPK and PI3K signaling pathways in human ASM (HASM) cells following TNF-α exposure. In this study, we investigated the regulatory effect of these miRNAs on other asthma-related genes. Microarray analysis using the Illumina platform was performed with total RNA extracted from miR-708 (or control miR)-transfected HASM cells. Inhibition of candidate inflammation-associated gene expression was further validated by qPCR and ELISA. The most significant biologic functions for the differentially expressed gene set included decreased inflammatory response, cytokine expression and signaling. qPCR revealed inhibition of expression of CCL11, CXCL10, CCL2 and CXCL8, while the release of CCL11 was inhibited in miR-708-transfected cells. Transfection of cells with miR-140-3p resulted in inhibition of expression of CCL11, CXCL12, CXCL10, CCL5 and CXCL8 and of TNF-α-induced CXCL12 release. In addition, expression of RARRES2, CD44 and ADAM33, genes known to contribute to the pathophysiology of asthma, were found to be inhibited in miR-708-transfected cells. These results demonstrate that miR-708 and miR-140-3p exert distinct effects on inflammation-associated gene expression and biological function of ASM cells. Targeting these miRNA networks may provide a novel therapeutic mechanism to down-regulate airway inflammation and ASM proliferation in asthma.

The parasitic worm-derived immunomodulator, ES-62 and its drug-like small molecule analogues exhibit therapeutic potential in a model of chronic asthma

Chronic asthma is associated with persistent lung inflammation and long-term remodelling of the airways that have proved refractory to conventional treatments such as steroids, despite their efficacy in controlling acute airway contraction and bronchial inflammation. As its recent dramatic increase in industrialised countries has not been mirrored in developing regions, it has been suggested that helminth infection may protect humans against developing asthma. Consistent with this, ES-62, an immunomodulator secreted by the parasitic worm Acanthocheilonema viteae, can prevent pathology associated with chronic asthma (cellular infiltration of the lungs, particularly neutrophils and mast cells, mucus hyper-production and airway thickening) in an experimental mouse model. Importantly, ES-62 can act even after airway remodelling has been established, arresting pathogenesis and ameliorating the inflammatory flares resulting from repeated exposure to allergen that are a debilitating feature of severe chronic asthma. Moreover, two chemical analogues of ES-62, 11a and 12b mimic its therapeutic actions in restoring levels of regulatory B cells and suppressing neutrophil and mast cell responses. These studies therefore provide a platform for developing ES-62-based drugs, with compounds 11a and 12b representing the first step in the development of a novel class of drugs to combat the hitherto intractable disorder of chronic asthma.

Matrix stiffness-modulated proliferation and secretory function of the airway smooth muscle cells

Multiple pulmonary conditions are characterized by an abnormal misbalance between various tissue components, for example, an increase in the fibrous connective tissue and loss/increase in extracellular matrix proteins (ECM). Such tissue remodeling may adversely impact physiological function of airway smooth muscle cells (ASMCs) responsible for contraction of airways and release of a variety of bioactive molecules. However, few efforts have been made to understand the potentially significant impact of tissue remodeling on ASMCs. Therefore, this study reports how ASMCs respond to a change in mechanical stiffness of a matrix, to which ASMCs adhere because mechanical stiffness of the remodeled airways is often different from the physiological stiffness. Accordingly, using atomic force microscopy (AFM) measurements, we found that the elastic modulus of the mouse bronchus has an arithmetic mean of 23.1 ± 14 kPa (SD) (median 18.6 kPa). By culturing ASMCs on collagen-conjugated polyacrylamide hydrogels with controlled elastic moduli, we found that gels designed to be softer than average airway tissue significantly increased cellular secretion of vascular endothelial growth factor (VEGF). Conversely, gels stiffer than average airways stimulated cell proliferation, while reducing VEGF secretion and agonist-induced calcium responses of ASMCs. These dependencies of cellular activities on elastic modulus of the gel were correlated with changes in the expression of integrin-β1 and integrin-linked kinase (ILK). Overall, the results of this study demonstrate that changes in matrix mechanics alter cell proliferation, calcium signaling, and proangiogenic functions in ASMCs.

Clonally expanded human airway smooth muscle cells exhibit morphological and functional heterogeneity

BACKGROUND

Mesenchyme-derived airway cell populations including airway smooth muscle (ASM) cells, fibroblasts and myofibroblasts play key roles in the pathogenesis of airway inflammation and remodeling. Phenotypic and functional characterisation of these cell populations are confounded by their heterogeneity in vitro. It is unclear which mechanisms underlie the creation of these different sub-populations.The study objectives were to investigate whether ASM cells are capable of clonal expansion and if so (i) what proportion possess this capability and (ii) do clonal populations exhibit variation in terms of morphology, phenotype, proliferation rates and pro-relaxant or pro-contractile signaling pathways.

METHODS

Early passage human ASM cells were subjected to single-cell cloning and their doubling time was recorded. Immunocytochemistry was performed to assess localization and levels of markers previously reported to be specifically associated with smooth muscle or fibroblasts. Finally functional assays were used to reveal differences between clonal populations specifically assessing mitogen-induced proliferation and pro-relaxant and pro-contractile signaling pathways.

RESULTS

Our studies provide evidence that a high proportion (58%) of single cells present within early passage human ASM cell cultures have the potential to create expanded cell populations. Despite being clonally-originated, morphological heterogeneity was still evident within these clonal populations as assessed by the range in expression of markers associated with smooth muscle cells. Functional diversity was observed between clonal populations with 10 μM isoproterenol-induced cyclic AMP responses ranging from 1.4 - 5.4 fold cf basal and bradykinin-induced inositol phosphate from 1.8 - 5.2 fold cf basal.

CONCLUSION

In summary we show for the first time that primary human ASM cells are capable of clonal expansion and that the resulting clonal populations themselves exhibit phenotypic plasticity.

CD4+ T cells enhance the unloaded shortening velocity of airway smooth muscle by altering the contractile protein expression

Abundant data indicate that pathogenesis in allergic airways disease is orchestrated by an aberrant T-helper 2 (Th2) inflammatory response. CD4(+) T cells have been localized to airway smooth muscle (ASM) in both human asthmatics and in rodent models of allergic airways disease, where they have been implicated in proliferative responses of ASM. Whether CD4(+) T cells also alter ASM contractility has not been addressed. We established an in vitro system to assess the ability of antigen-stimulated CD4(+) T cells to modify contractile responses of the Brown Norway rat trachealis muscle. Our data demonstrated that the unloaded velocity of shortening (Vmax) of ASM was significantly increased upon 24 h co-incubation with antigen-stimulated CD4(+) T cells, while stress did not change. Enhanced Vmax was dependent upon contact between the CD4(+) T cells and the ASM and correlated with increased levels of the fast (+)insert smooth muscle myosin heavy chain isoform. The levels of myosin light chain kinase and myosin light chain phosphorylation were also increased within the muscle. The alterations in mechanics and in the levels of contractile proteins were transient, both declining to control levels after 48 h of co-incubation. More permanent alterations in muscle phenotype might be attainable when several inflammatory cells and mediators interact together or after repeated antigenic challenges. Further studies will await new tissue culture methodologies that preserve the muscle properties over longer periods of time. In conclusion, our data suggest that inflammatory cells promote ASM hypercontractility in airway hyper-responsiveness and asthma.

Respiratory allergies: a general overview of remedies, delivery systems, and the need to progress

The spread of respiratory allergies is increasing in parallel with the alarm of the scientific community. Evidently, our knowledge of the onset mechanisms of these diseases and, as a consequence, of the available remedies is inadequate. This review provides a brief, general description of current therapeutic resources and the state of research with regard to both drugs and medical devices in order to highlight their limits and the urgent need for progress. Increasing the amount of basic biochemical research will improve our knowledge of such onset mechanisms and the potential efficacy of therapeutic preparations.

Ultrashort-TE MRI longitudinal study and characterization of a chronic model of asthma in mice: inflammation and bronchial remodeling assessment

Asthma is a chronic disease characterized by bronchial hyperresponsiveness (BHR), bronchial inflammation and remodeling. The great improvements in (1)H MRI ultrashort-TE (UTE) sequences in the last decade have allowed lung images with high-resolution and good signal-to-noise ratio to be obtained in parenchymal tissues. In this article, we present a UTE (1)H MRI high-resolution study of a chronic model of asthma in mice with the aim to longitudinally assess the main features of asthma using a fully noninvasive approach. Balb/c mice (n = 6) were sensitized with ovalbumin over a period of 75 days. The control group (n = 3) received normal saline on the same days. MRI acquisitions were performed on days 0, 38 and 78 to study the inflammatory volumes and bronchial remodeling (peribronchial signal intensity index, PBSI). Plethysmographic studies were performed on days 0, 39 and 79 to assess BHR to methacholine using the enhanced pause (Penh) ratio. The average inflammatory volume measured by MRI in the ovalbumin group (15.6 ± 2.4 μL) was increased significantly relative to control mice (-0.3 ± 0.7 μL) on day 38. The inflammatory volume was larger (34.2 ± 3.1 μL) on day 78 in the ovalbumin group. PBSI was significantly higher in the ovalbumin group on day 78 (1.53 ± 0.08) relative to the control group (1.16 ± 0.10), but not on day 38. After sensitization, asthmatic mice presented BHR to methacholine on days 39 and 79. Penh ratios correlated significantly with the inflammatory volume on day 39 and with the PBSI on day 79. This study shows, for the first time, that high-resolution UTE (1)H MRI of the lungs may allow the noninvasive quantification of peribronchial eosinophilic inflammation with airways occlusion by mucus and of bronchial remodeling in a murine asthma model that correlates with functional parameters.

A new approach for the study of lung smooth muscle phenotypes and its application in a murine model of allergic airway inflammation

Phenotypes of lung smooth muscle cells in health and disease are poorly characterized. This is due, in part, to a lack of methodologies that allow for the independent and direct isolation of bronchial smooth muscle cells (BSMCs) and vascular smooth muscle cells (VSMCs) from the lung. In this paper, we describe the development of a bi-fluorescent mouse that permits purification of these two cell populations by cell sorting. By subjecting this mouse to an acute allergen based-model of airway inflammation that exhibits many features of asthma, we utilized this tool to characterize the phenotype of so-called asthmatic BSMCs. First, we examined the biophysical properties of single BSMCs from allergen sensitized mice and found increases in basal tone and cell size that were sustained ex vivo. We then generated for the first time, a comprehensive characterization of the global gene expression changes in BSMCs isolated from the bi-fluorescent mice with allergic airway inflammation. Using statistical methods and pathway analysis, we identified a number of differentially expressed mRNAs in BSMCs from allergen sensitized mice that code for key candidate proteins underlying changes in matrix formation, contractility, and immune responses. Ultimately, this tool will provide direction and guidance for the logical development of new markers and approaches for studying human lung smooth muscle.

IL-13 R110Q, a Naturally Occurring IL-13 Polymorphism, Confers Enhanced Functional Activity in Cultured Human Bronchial Smooth Muscle Cells

Purpose

Interleukin (IL)-13, a Th2-type cytokine, plays a pivotal role in the pathogenesis of asthma through its direct effects on airway smooth muscles. A naturally occurring IL-13 polymorphism, R110Q, is strongly associated with increased total serum IgE levels and asthma. In the present study, we aimed to determine whether the IL-13 R110Q variant would display different biochemical properties or altered functions in comparison with wild-type (WT) IL-13 in cultured human bronchial smooth muscle cells (hBSMCs).

Methods

Culture supernatants and cell proteins were collected from cultured hBSMCs that were treated with 50 ng/mL IL-13 or IL-13 R110Q for 24 hours. Eotaxin released into hBSMC culture medium was determined by ELISA. The expression levels of the high-affinity IgE receptor (FcεRI) α-chain, smooth muscle-specific actin alpha chain (α-SMA), smooth muscle myosin heavy chain (SmMHC), and calreticulin in the cells were measured on Western blots.

Results

Compared with WT IL-13, treatment with the IL-13 R110Q variant resulted in a significant increase in eotaxin release as well as significant, although modest, increases in the expression levels of α-SMA, SmMHC, calreticulin, and FcεRI α-chain.

Conclusions

The results of the present study suggenst that the IL-13 R110Q variant may enhance enhanced functional activities in hBSMCs.

Diagnostic, functional, and therapeutic roles of microRNA in allergic diseases

Allergic inflammation is accompanied by the coordinated expression of a myriad of genes and proteins that initiate, sustain, and propagate immune responses and tissue remodeling. MicroRNAs (miRNAs) are a class of short single-stranded RNA molecules that posttranscriptionally silence gene expression and have been shown to fine-tune gene transcriptional networks because single miRNAs can target hundreds of genes. Considerable attention has been focused on the key role of miRNAs in regulating homeostatic immune architecture and acquired immunity. Recent studies have identified miRNA profiles in multiple allergic inflammatory diseases, including asthma, eosinophilic esophagitis, allergic rhinitis, and atopic dermatitis. Specific miRNAs have been found to have critical roles in regulating key pathogenic mechanisms in allergic inflammation, including polarization of adaptive immune responses and activation of T cells (eg, miR-21 and miR-146), regulation of eosinophil development (eg, miR-21 and miR-223), and modulation of IL-13-driven epithelial responses (eg, miR-375). This review discusses recent advances in our understanding of the expression and function of miRNAs in patients with allergic inflammation, their role as disease biomarkers, and perspectives for future investigation and clinical utility.

The pharmacological modulation of allergen-induced asthma

Aeroallergens are the most common triggers for the development of asthma. Recent birth cohort studies have identified viral infections occurring against a background of aeroallergen sensitization as a potent risk factor for initiation of asthma. Viral infection enhances immunopathogenic potential of pre-existing inhalant allergy via modulating airway mucosal dendritic cells. By using an allergen inhalation challenge clinical model, studies have shown that the late asthma response (LAR) is associated with more pronounced allergen-induced airway inflammation and airway hyperresponsiveness. The degree of airway eosinophilia, regulated by bone marrow progenitor cells and interleukin-5 level, correlates with the magnitude of the LAR and the increase in hyperresponsiveness. Both myeloid and plasmacytoid dendritic cell subsets have been involved in the pathogenesis of allergen-induced LAR. Myeloid dendritic cells are responsible for the allergen presentation and induction of inflammation and plasmacytoid dendritic cells play a role in the resolution of allergen-induced inflammation. A variety of potential new classes of asthma medication has also been evaluated with the allergen inhalation challenge in mild asthmatic subjects. Examples are TPI ASM8, an inhaled anti-sense oligonucleotide drug product, which attenuated both early and LARs via inhibition of the target gene mRNA of chemokine receptor 3, and the common β chain of interleukin-3, interleukin-5 and granulocyte-macrophage colony-stimulating factor receptor. Anti-human antibody interleukin-13 (IM-638) significantly attenuated both early and late allergen-induced asthma response. Pitrakinra, which targets both interleukin-4 and interleukin-13, substantially diminishes allergen-induced airway responses. Allergen-induced airway responses are a valuable way to evaluate the activity of possible new therapies in asthmatic airways.