Pharmacotherapy and airway remodelling in asthma?

Single-cell analysis reveals alterations in cellular composition and cell-cell communication associated with airway inflammation and remodeling in asthma

BACKGROUND

Asthma is a heterogeneous disease characterized by airway inflammation and remodeling, whose pathogenetic complexity was associated with abnormal responses of various cell types in the lung. The specific interactions between immune and stromal cells, crucial for asthma pathogenesis, remain unclear. This study aims to determine the key cell types and their pathological mechanisms in asthma through single-cell RNA sequencing (scRNA-seq).

METHODS

A 16-week mouse model of house dust mite (HDM) induced asthma (n = 3) and controls (n = 3) were profiled with scRNA-seq. The cellular composition and gene expression profiles were assessed by bioinformatic analyses, including cell enrichment analysis, trajectory analysis, and Gene Set Enrichment Analysis. Cell-cell communication analysis was employed to investigate the ligand-receptor interactions.

RESULTS

The asthma model results in airway inflammation coupled with airway remodeling and hyperresponsiveness. Single-cell analysis revealed notable changes in cell compositions and heterogeneities associated with airway inflammation and remodeling. GdT17 cells were identified to be a primary cellular source of IL-17, related to inflammatory exacerbation, while a subpopulation of alveolar macrophages exhibited numerous significantly up-regulated genes involved in multiple pathways related to neutrophil activities in asthma. A distinct fibroblast subpopulation, marked by elevated expression levels of numerous contractile genes and their regulators, was observed in increased airway smooth muscle layer by immunofluorescence analysis. Asthmatic stromal-immune cell communication significantly strengthened, particularly involving GdT17 cells, and macrophages interacting with fibroblasts. CXCL12/CXCR4 signaling was remarkedly up-regulated in asthma, predominantly bridging the interaction between fibroblasts and immune cell populations. Fibroblasts and macrophages could jointly interact with various immune cell subpopulations via the CCL8/CCR2 signaling. In particular, fibroblast-macrophage cell circuits played a crucial role in the development of airway inflammation and remodeling through IL1B paracrine signaling.

CONCLUSIONS

Our study established a mouse model of asthma that recapitulated key pathological features of asthma. ScRNA-seq analysis revealed the cellular landscape, highlighting key pathological cell populations associated with asthma pathogenesis. Cell-cell communication analysis identified the crucial ligand-receptor interactions contributing to airway inflammation and remodeling. Our findings emphasized the significance of cell-cell communication in bridging the possible causality between airway inflammation and remodeling, providing valuable hints for therapeutic strategies for asthma.

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.

Pharmacological Properties of 2,4,6-Trihydroxy-3-Geranyl Acetophenone and the Underlying Signaling Pathways: Progress and Prospects

2,4,6-Trihydroxy-3-geranyl acetophenone (tHGA) is a bioactive phloroglucinol compound found in Melicope pteleifolia (Champ. ex Benth.) T.G.Hartley, a medicinal plant vernacularly known as “tenggek burung”. A variety of phytochemicals have been isolated from different parts of the plant including leaves, stems, and roots by using several extraction methods. Specifically, tHGA, a drug-like compound containing phloroglucinol structural core with acyl and geranyl group, has been identified in the methanolic extract of the young leaves. Due to its high nutritional and medicinal values, tHGA has been extensively studied by using various experimental models. These studies have successfully discovered various interesting pharmacological activities of tHGA such as anti-inflammatory, endothelial and epithelial barrier protective, anti-asthmatic, anti-allergic, and anti-cancer. More in-depth investigations later found that these activities were attributable to the modulatory actions exerted by tHGA on specific molecular targets. Despite these findings, the association between the mechanisms and signaling pathways underlying each pharmacological activity remains largely unknown. Also, little is known about the medicinal potentials of tHGA as a drug lead in the current pharmaceutical industry. Therefore, this mini review aims to summarize and relate the pharmacological activities of tHGA in terms of their respective mechanisms of action and signaling pathways in order to present a perspective into the overall modulatory actions exerted by tHGA. Besides that, this mini review will also pinpoint the unexplored potentials of this compound and provide some valuable insights into the potential applications of tHGA which may serve as a guide for the development of modern medication in the future.

Novel phosphodiesterases inhibitors from the group of purine-2,6-dione derivatives as potent modulators of airway smooth muscle cell remodelling

Airway remodelling (AR) is an important pathological feature of chronic asthma and chronic obstructive pulmonary disease. The etiology of AR is complex and involves both lung structural and immune cells. One of the main contributors to airway remodelling is the airway smooth muscle (ASM), which is thickened by asthma, becomes more contractile and produces more extracellular matrix. As a second messenger, adenosine 3',5'-cyclic monophosphate (cAMP) has been shown to contribute to ASM cell (ASMC) relaxation as well as to anti-remodelling effects in ASMC. Phosphodiesterase (PDE) inhibitors have drawn attention as an interesting new group of potential anti-inflammatory and anti-remodelling drugs. Recently, new hydrazide and amide purine-2,6-dione derivatives with anti-inflammatory properties have been synthesized by our team (compounds 1 and 2). We expanded our study of their PDE selectivity profile, ability to increase intracellular cAMP levels, metabolic stability and, above all, their capacity to modulate cell responses associated with ASMC remodelling. The results show that both compounds have subtype specificity for several PDE isoforms (including inhibition of PDE1, PDE3, PDE4 and PDE7). Interestingly, such combined PDE subtype inhibition exerts improved anti-remodelling efficacies against several ASMC-induced responses such as proliferation, contractility, extracellular matrix (ECM) protein expression and migration when compared to other non-selective and selective PDE inhibitors. Our findings open novel perspectives in the search for new chemical entities with dual anti-inflammatory and anti-remodelling profiles in the group of purine-2,6-dione derivatives as broad-spectrum PDE inhibitors.

The Role of Airway Myofibroblasts in Asthma

Airway remodeling is a characteristic feature of asthma and is thought to play an important role in the pathogenesis of airway hyperresponsiveness. Myofibroblasts are key structural cells involved in injury and repair, and there is evidence that dysregulation of their normal function contributes to airway remodeling. Despite the importance of myofibroblasts, a lack of specific cellular markers and inconsistent nomenclature have limited recognition of their key role in airway remodeling. Myofibroblasts are increased several-fold in the airways in asthma, in proportion to the severity of the disease. Myofibroblasts are postulated to be derived from both tissue-resident and bone marrow-derived cells, depending on the stage of injury and the tissue. A small number of studies have demonstrated attenuation of myofibroblast numbers and also reversal of established myofibroblast populations in asthma and other inflammatory processes. In this article, we review what is currently known about the biology of myofibroblasts in the airways in asthma and identify potential targets to reduce or reverse the remodeling process. However, further translational research is required to better understand the mechanistic role of the myofibroblast in asthma.

IL33/ST2 contributes to airway remodeling via p-JNK MAPK/STAT3 signaling pathway in OVA-induced allergic airway inflammation in mice

Aim of this study: Airway remodeling, which encompasses structural changes in airway is a main feature of asthma. Interleukin-33 (IL-33) has been reported to be a vital cytokine in airway remodeling in asthma, but the underlying mechanisms are not clear yet. This study focused on discussing the role of IL-33 in airway remodeling in asthma. Material and methods: Female BALB/c mice were divided into a control group, an OVA induced allergic airway disease group and an anti-ST2 antibody intervention group. Immunohistochemistry and western blot were performed to detect IL-33, ST2 expression in addition to airway remodeling markers a-smooth muscle actin (a-SMA) and type 1 collagen in OVA-induced mice model. Levels of p-JNK and p-STAT3 activation in mice were detected by western blot. Human lung fibroblast (HLF) were stimulated with rhIL-33, anti-ST2 antibody and JNK inhibitor sp600125 and levels of JNK and STAT3 activation were determined via western blot and immunofluorescence staining. Results: Anti-ST2 treatment inhibited JNK/STAT3 phosphorylation and airway remodeling in OVA-induced mouse model. IL-33 induced a-SMA and collagen 1 expression was inhibited by anti-ST2 antibody and sp600125 treatment via decreased JNK/STAT3 phosphorylation in human lung fibroblast. Conclusions: IL-33 promoted airway remodeling by interacting with ST2 to activate the JNK/STAT3 signaling pathway in asthma.

IL-32γ attenuates airway fibrosis by modulating the integrin-FAK signaling pathway in fibroblasts

Background

Fibrosis in severe asthma often leads to irreversible organ dysfunction. However, the mechanism that regulates fibrosis remains poorly understood. Interleukin (IL)-32 plays a role in several chronic inflammatory diseases, including severe asthma. In this study, we investigated whether IL-32 is involved in fibrosis progression in the lungs.

Methods

Murine models of chronic airway inflammation induced by ovalbumin and Aspergillus melleus protease and bleomycin-induced pulmonary fibrosis were employed. We evaluated the degree of tissue fibrosis after treatment with recombinant IL-32γ (rIL-32γ). Expression of fibronectin and α-smooth muscle actin (α-SMA) was examined and the transforming growth factor (TGF)-β-related signaling pathways was evaluated in activated human lung fibroblasts (MRC-5 cells) treated with rIL-32γ.

Results

rIL-32γ significantly attenuated collagen deposition and α-SMA production in both mouse models. rIL-32γ inhibited the production of fibronectin and α-SMA in MRC-5 cells stimulated with TGF-β. Additionally, rIL-32γ suppressed activation of the integrin-FAK-paxillin signaling axis but had no effect on the Smad and non-Smad signaling pathways. rIL-32γ localized outside of MRC-5 cells and inhibited the interaction between integrins and the extracellular matrix without directly binding to intracellular FAK and paxillin.

Conclusions

These results demonstrate that IL-32γ has anti-fibrotic effects and is a novel target for preventing fibrosis.

Electronic supplementary material

The online version of this article (10.1186/s12931-018-0863-3) contains supplementary material, which is available to authorized users.

The Variants in the 3' Untranslated Region of the Matrix Metalloproteinase 9 Gene as Modulators of Treatment Outcome in Children with Asthma

PURPOSE

The maintaining of asthma control is difficult due to high variability in response to therapy among patients. Since matrix metalloproteinase 9 (MMP9) is implicated in inflammation and remodeling of asthmatic airways, it could be associated with adequate response to asthma therapy. The aim of this study was to investigate whether variants in 3' end of the MMP9 gene are associated with clinical phenotype and responsiveness to treatment in children with asthma.

METHODS

The study included 127 asthmatic children from Slovenia. Variants in the 3' end of the MMP9 gene were analyzed by direct DNA sequencing and the obtained results were correlated with clinical parameters.

RESULTS

Two variants were detected, rs13925 and rs20544. For the variant rs20544, statistically significant difference in airway hyperresponsiveness (p = 0.011) and asthma control (p = 0.049) between genotypes was found. Patients with TT genotype had lower airway sensitivity, and after 12 months of treatment showed significant improvement in Asthma Control Test (ACT) scores compared to CC and CT genotype. For the variant rs13925, the association with lung function was observed. The carriers of A allele showed noticeable improvement of lung function after the first 6 months of treatment in comparison to the carriers of G allele (p = 0.046).

CONCLUSION

The main finding of our study is the association of MMP9 genotypes rs20544 TT and rs13925 AA and AG with better asthma control, and indirectly better response to treatment. Based on these results, MMP9 deserves further research as a potential predictive biomarker for asthma.

Developments in the field of allergy in 2016 through the eyes of Clinical and Experimental Allergy

In this article, we described the development in the field of allergy as described by Clinical and Experimental Allergy in 2016. Experimental models of allergic disease, basic mechanisms, clinical mechanisms, allergens, asthma and rhinitis, and clinical allergy are all covered.

Role of canonical transient receptor potential channel-3 in acetylcholine-induced mouse airway smooth muscle cell proliferation

AIMS

Canonical transient receptor potential channel-3 (TRPC3)-encoded Ca²⁺-permeable nonselective cation channel (NSCC) has been proven to be an important native constitutively active channel in airway smooth muscle cell (ASMC), which plays significant roles in physiological and pathological conditions by controlling Ca²⁺ homeostasis in ASMC. Acetylcholine (ACh) is generally accepted as a contractile parasympathetic neurotransmitter in the airway. Recently studies have revealed the pathological role of ACh in airway remodeling, however, the mechanisms remain unclear. Here, we investigated the role of TRPC3 in ACh-induced ASMC proliferation.

MATERIALS AND METHODS

Primary mouse ASMCs were cultured with or without ACh treatment, then cell viability, TRPC3 expression, NSCC currents and [Ca²⁺]_i changes were examined by MTT assay, cell counting, Western blotting, standard whole-cell patch clamp recording and calcium imaging, respectively. Small interfering RNA (siRNA) technology was used to confirm the contribution of TRPC3 to ACh-induced ASMC proliferation.

KEY FINDINGS

TRPC3 blocker Gd³⁺, antibody or siRNA largely inhibited ACh-induced up-regulation of TRPC3 protein, enhancement of NSCC currents, resting [Ca²⁺]_i and KCl-induced changes in [Ca²⁺]_i, eventually inhibiting ACh-induced ASMC proliferation.

SIGNIFICANCE

Our data suggested ACh could induce ASMC proliferation, and TRPC3 may be involved in ACh-induced ASMC proliferation that occurs with airway remodeling.

Airway remodeling in asthma: what really matters

Airway remodeling is generally quite broadly defined as any change in composition, distribution, thickness, mass or volume and/or number of structural components observed in the airway wall of patients relative to healthy individuals. However, two types of airway remodeling should be distinguished more clearly: (1) physiological airway remodeling, which encompasses structural changes that occur regularly during normal lung development and growth leading to a normal mature airway wall or as an acute and transient response to injury and/or inflammation, which ultimately results in restoration of a normal airway structures; and (2) pathological airway remodeling, which comprises those structural alterations that occur as a result of either disturbed lung development or as a response to chronic injury and/or inflammation leading to persistently altered airway wall structures and function. This review will address a few major aspects: (1) what are reliable quantitative approaches to assess airway remodeling? (2) Are there any indications supporting the notion that airway remodeling can occur as a primary event, i.e., before any inflammatory process was initiated? (3) What is known about airway remodeling being a secondary event to inflammation? And (4), what can we learn from the different animal models ranging from invertebrate to primate models in the study of airway remodeling? Future studies are required addressing particularly pheno-/endotype-specific aspects of airway remodeling using both endotype-specific animal models and “endotyped” human asthmatics. Hopefully, novel in vivo imaging techniques will be further advanced to allow monitoring development, growth and inflammation of the airways already at a very early stage in life.

An orally active geranyl acetophenone attenuates airway remodeling in a murine model of chronic asthma

2,4,6-Trihydroxy-3-geranyl acetophenone (tHGA) is a synthetic compound that is naturally found in Melicope ptelefolia. We had previously demonstrated that parenteral administration of tHGA reduces pulmonary inflammation in OVA-sensitized mice. In this study, we evaluated the effect of orally administered tHGA upon airway remodeling in a murine model of chronic asthma. Female BALB/C mice were sensitized intraperitoneally with ovalbumin (OVA) on day 0, 7 and 14, followed by aerosolized 1% OVA 3 times per week for 6 weeks. Control groups were sensitized with saline. OVA sensitized animals were either treated orally with vehicle (saline with 1% DMSO and Tween 80), tHGA (80, 40, 20mg/kg) or zileuton (30mg/kg) 1h prior to each aerosolized OVA sensitization. On day 61, mice underwent methacholine challenge to determine airway hyperresponsiveness prior to collection of bronchoalveolar lavage (BAL) fluid and lung samples. BAL fluid inflammatory cell counts and cytokine concentrations were evaluated while histological analysis and extracellular matrix protein concentrations were determined on collected lung samples. Oral tHGA treatment attenuated airway hyperresponsiveness and inhibited airway remodeling in a dose-dependent fashion. tHGA's effect on airway remodeling could be attributed to the reduction of inflammatory cell infiltration and decreased expression of cytokines associated with airway remodeling. Oral administration of tHGA attenuates airway hyperresponsiveness and remodeling in OVA-induced BALB/c mice. tHGA is an interesting compound that should be evaluated further for its possible role as an alternative non-steroidal pharmacological approach in the management of asthma.

Bronchoconstriction Induces Structural and Functional Airway Alterations in Non-sensitized Rats

The impact of mechanical forces on pathogenesis of airway remodeling and the functional consequences in asthma remains to be fully established. In the present study, we investigated the effect of repeated bronchoconstriction induced by methacholine (MCh) on airway remodeling and airway hyperresponsiveness (AHR) in rats with or without sensitization to an external allergen. We provide evidence that repeated bronchoconstriction, using MCh, alone induces airway inflammation and remodeling as well as AHR in non-allergen-sensitized rats. Also, we found that the airways are structurally and functionally altered by bronchoconstriction induced by either allergen or MCh in allergen-sensitized animals. This finding provides a new animal model for the development of airway remodeling and AHR in mammals and can be used for studying the complex reciprocal relationship between bronchoconstriction and airway inflammation. Further studies on presented animal models are required to clarify the exact mechanisms underlying airway remodeling due to bronchoconstriction and the functional consequences.

Airway Remodeling in Chronic Obstructive Pulmonary Disease and Asthma: the Role of Matrix Metalloproteinase-9

Chronic obstructive pulmonary disease (COPD) and asthma are both associated with airflow restriction and progressive remodeling, which affect the respiratory tract. Among various biological factors involved in the pathomechanisms of both diseases, proteolytic enzymes--matrix metalloproteinases (MMPs)--play an important role, especially MMP-9. In this review, the authors discuss the current topics of research concerning the possible role of MMP-9 in both mentioned diseases. They include the analysis of protein levels, nucleotide polymorphisms of MMP-9 gene and their possible correlation with asthma and COPD. Finally, the authors refer to the studies on MMP-9 inhibition as a new perspective for increasing the effectiveness of treatment in asthma and COPD.

Statins in Asthma: Potential Beneficial Effects and Limitations

Asthma's sustenance as a global pandemic, across centuries, can be attributed to the lack of an understanding of its workings and the inability of the existing treatment modalities to provide a long lasting cure without major adverse effects. The discovery of statins boosted by a better comprehension of the pathophysiology of asthma in the past few decades has opened up a potentially alternative line of treatment that promises to be a big boon for the asthmatics globally. However, the initial excellent results from the preclinical and animal studies have not borne the results in clinical trials that the scientific world was hoping for. In light of this, this review analyzes the ways by which statins could benefit in asthma via their pleiotropic anti-inflammatory properties and explain some of the queries raised in the previous studies and provide recommendations for future studies in this field.

Urinary leukotriene E4 levels in atopic and non-atopic preschool children with recurrent episodic (viral) wheezing: a potential marker?

Backround: Reliable biological markers for the differentiation of asthma phenotypes in preschool children with wheezing are lacking. The purpose of the study is to assess the relationship of urinary Leukotriene E4 (U-LTE4) to particular asthma phenotypes in preschool children with recurrent episodic (viral) wheezing following upper respiratory tract infections with or without atopic predisposition.

METHODS

Ninety-six preschool patients with recurrent episodic wheezing participated, 52 atopic and 44 non-atopic, during exacerbation and in remission. Exacerbation was defined on clinical basis (wheeze in the presence of coryzal symptoms). Atopy was determined by specific serum IgE measurement and skin-prick testing. U-LTE4 was determined by enzyme immunoassay. Thirty-six age-matched, non-asthmatic, non-atopic children served as controls.

RESULTS

During exacerbation, U-LTE4 was significantly higher in all children with recurrent episodic wheezing in comparison to A: Remission: 642.20 ± 268 versus 399.45 ± 204, p value <0.001 and B:

CONTROLS

642.20 ± 268 versus 271.39 ± 83, p value <0.001. Atopic patients demonstrated significantly higher levels of U-LTE4 compared to non-atopic, both during exacerbation 872.13 ± 246 versus 613.15 ± 150, p value = 0.0013 and during remission 507.59 ± 182 versus 283.59 ± 160, p value <0.001. During remission, a highly significant difference of U-LTE4 was found when controls were compared to atopic patients: 271.39 ± 83 versus 507.59 ± 182, p value = 0.002 but not when compared to non-atopic ones: 271.39 ± 83 versus 283.59 ± 160, p value = 0.432.

CONCLUSION

U-LTE4 is strongly associated with the acute wheeze episode in preschool children, more so in atopics. Increased basal levels of U-LTE4 occur only in atopics. This suggests a potential role of U-LTE4 as a marker of atopic, virus-induced asthma in preschool children.

Central role of cellular senescence in TSLP-induced airway remodeling in asthma

Background

Airway remodeling is a repair process that occurs after injury resulting in increased airway hyper-responsiveness in asthma. Thymic stromal lymphopoietin (TSLP), a vital cytokine, plays a critical role in orchestrating, perpetuating and amplifying the inflammatory response in asthma. TSLP is also a critical factor in airway remodeling in asthma.

Objectives

To examine the role of TSLP-induced cellular senescence in airway remodeling of asthma invitro and invivo.

Methods

Cellular senescence and airway remodeling were examined in lung specimens from patients with asthma using immunohischemical analysis. Both small molecule and shRNA approaches that target the senescent signaling pathways were used to explore the role of cellular senescence in TSLP-induced airway remodeling invitro. Senescence-Associated β-galactosidase (SA-β-Gal) staining, and BrdU assays were used to detect cellular senescence. In addition, the Stat3-targeted inhibitor, WP1066, was evaluated in an asthma mouse model to determine if inhibiting cellular senescence influences airway remodeling in asthma.

Results

Activation of cellular senescence as evidenced by checkpoint activation and cell cycle arrest was detected in airway epithelia samples from patients with asthma. Furthermore, TSLP-induced cellular senescence was required for airway remodeling invitro. In addition, a mouse asthma model indicates that inhibiting cellular senescence blocks airway remodeling and relieves airway resistance.

Conclusion

TSLP stimulation can induce cellular senescence during airway remodeling in asthma. Inhibiting the signaling pathways of cellular senescence overcomes TSLP-induced airway remodeling.

Lost to follow-up in asthmatics does not mean treatment failure: causes and clinical outcomes of non-adherence to outpatient treatment in adult asthma

Purpose

Long-term asthma management is recommended to asthmatics; however, many patients do not adhere to follow-up treatment. It is unclear why many asthmatics do not adhere to follow-up treatment and long-term clinical course after discontinuation of asthma management. This study investigates the factors associated with loss to follow-up and observes the clinical course in asthmatics who discontinued asthma treatment.

Methods

A retrospective investigation was conducted after reviewing medical records of adult patients who were newly diagnosed with asthma at a university hospital in Seoul, South Korea from January 2005 to March 2007. We compared baseline demographics and the clinical and laboratory profiles of patients to see if they successfully adhered to the treatment at an outpatient clinic for at least 3 years. The clinical course and asthma control status were surveyed by telephone for patients who were lost to follow-up within 3 years.

Results

A total of 351 (73.9%) out of 475 patients were lost to follow-up within 3 years of asthma diagnosis. Patients lost to follow-up were younger and had clinical features of less severe asthma at time of diagnosis (higher FEV1 and PC20, and lower grade treatments) compared to patients who adhered to the follow-up for longer than 3 years (all P<0.05). Among the 198 responders to the telephone survey, 124 responders (62.6%) answered that they eventually discontinued asthma medication. A significantly higher proportion of the 124 responders who discontinued asthma treatment maintained symptom improvement compared to the 74 responders who continued asthma medication (77.4% vs. 55.4%, P=0.003).

Conclusions

Almost three quarters of newly diagnosed asthmatics discontinued asthma medication within 3 years despite a medical recommendation. There are considerable numbers of asthmatics who can maintain long-term asthma control status without medication.

Fixed airflow obstruction among nonsmokers with asthma:a case-comparison study

BACKGROUND

Airflow obstruction in asthma is usually reversible, but fixed obstruction develops in some individuals. Little is known about risk factors for development of fixed airflow obstruction in nonsmokers with asthma.

METHODS

This case-comparison study recruited nonsmokers aged over 45 years with physician-diagnosed asthma from specialist outpatient clinics and primary care. Two age-matched groups were recruited on the basis of spirometry: anobstructed group (post-bronchodilator FEV(1) ≤ 70% predicted, FEV1/FVC ratio < lower limit of normal) and a control group with normal lung function. Subjects completed a questionnaire and interview, and underwent spirometry, venesection, exhaled nitric oxide (ENO) measurement, allergen skinprick testing, and formal lung function testing.

RESULTS

Thirty-four obstructed subjects and 40 controls participated in the study. Obstructed subjects exhibited greater evidence of systemic inflammation, abnormal glucose homeostasis, and central obesity than controls. Obstructed subjects reported longer duration of asthma, and childhood respiratory infection was commoner in that group. Metabolic syndrome prevalence was similar between groups, but several features of insulin resistance were associated with reduced FEV(1). Cough and sputum were common among controls.

CONCLUSIONS

Risk of fixed airflow obstruction may correlate with lifetime asthma duration. Individuals with coexisting asthma and fixed airflow obstruction have heightened systemic inflammation. A variety of chronic respiratory symptoms are common among "healthy" nonsmokers with asthma.

Thymic stromal lymphopoietin promotes asthmatic airway remodelling in human lung fibroblast cells through STAT3 signalling pathway

This study aimed to identify the role and regulation of thymic stromal lymphopoietin (TSLP) in asthmatic airway remodelling. To identify the expression of TSLP, α smooth muscle actin (α-SMA) and collagen I in bronchial tissues, bronchial biopsy specimens were collected from patients with asthma and healthy controls and stained with specific antibodies, respectively. To characterize the signalling pathways regulated by TSLP, we silenced or overexpressed TSLP in human lung fibroblast (HLF-1) cells by shRNA approaches or transfection and detected the expression of TSLP receptor (TSLPR) by enzyme-linked immunosorbent assay and Western blot analysis. In TSLP signalling pathway, the protein expression of total signal transducer and activator of transcription 3 (STAT3), STAT5, the phosphorylation of STAT3 (pSTAT3) and STAT5 (pSTAT5), TSLP, α-SMA and collagen I were also detected by Western blotting. In addition, the α-SMA, collagen I and mRNA expression were determined by real-time reverse-transcription. To further confirm the TSLP-STAT3 signalling pathway in HLF-1 cells, we inhibited STAT3 activity by targeted small molecules and then detected TSLP-induced expression of α-SMA and collagen I in both mRNA and protein levels by quantitative real-time reverse-transcription and Western blotting, respectively. First, overexpression of TSLP, α-SMA and collagen I was detected in epithelium collected from patients with asthma. Second, STAT3 activity and the expression of α-SMA and collagen I were controlled, regulated by TSLP. Specifically, the pSTAT3, α-SMA and collagen I were induced by the introduction of TSLP in HLF-1 cells, and the repression of α-SMA and collagen I was detected after TSLP silencing. Third, no changes of pSTAT5 were found in the presence of the STAT3 inhibitor, and TSLP-induced α-SMA and collagen I upregulation is in a STAT3 dependent manner. If we inhibit STAT3 activity by STAT3 targeted small molecules, TSLP-induced α-SMA and collagen I upregulation cannot be detected. The functions of TSLP in asthmatic airway remodelling were performed through STAT3 signalling pathway.

Corticosteroid administration reduces the concentration of hyaluronan in bronchoalveolar lavage in a murine model of eosinophilic airway inflammation

OBJECTIVE

To analyze the effect of corticosteroid administration on the concentration of hyaluronan (HA) in bronchoalveolar lavage (BAL) in a murine model of eosinophilic airway inflammation and to study the mechanisms involved.

MATERIALS AND METHODS

Untreated-mice or mice treated with 1 μg/g/day betamethasone (Bm) or 0.25 μg/g/day(-1) budesonide (Bd) were sensitized and challenged with Dermatophagoides pteronyssinus (Dp) or saline (control group). The concentration of HA in BAL was determined by ELISA. In vitro migration assays were performed using a Boyden chamber and the expression of HA synthases (HAS) was analyzed by RT-PCR.

RESULTS

We found a significant increase (P < 0.01) in the levels of HA in BAL from Dp-treated mice that was prevented by Bm or Bd. Corticosteroids also inhibited the increase in HAS expression, and the phosphorylation of Akt and ERK in the lungs of challenged mice. Finally, we found that low molecular weight HA induces the chemotaxis of BAL cells in vitro through a mechanism mediated by CD44.

CONCLUSION

We conclude that corticosteroids prevent the increase in HA in BAL from Dp-challenged mice. This effect is associated with reduced expression of HAS and reduced phosphorylation of Akt and ERK in the lungs of challenged mice.

Can anti-IgE therapy prevent airway remodeling in allergic asthma?

Airway remodeling is a central feature of asthma. It is exemplified by thickening of the lamina reticularis and structural changes to the epithelium, submucosa, smooth muscle, and vasculature of the airway wall. Airway remodeling may result from persistent airway inflammation. Immunoglobulin E (IgE) is an important mediator of allergic reactions and has a central role in airway inflammation and asthma-related symptoms. Anti-IgE therapies (such as omalizumab) have the potential to block an early step in the allergic cascade and therefore have the potential to reduce airway remodeling. The reduction in free IgE levels following anti-IgE therapy leads to reductions in high-affinity IgE receptor (FcεRI) expression on mast cells, basophils, and dendritic cells. This combined effect results in attenuation of several markers of inflammation, including peripheral and bronchial tissue eosinophilia and levels of granulocyte macrophage colony-stimulating factor, interleukin (IL)-2, IL-4, IL-5, and IL-13. Considering the previously demonstrated anti-inflammatory effects of anti-IgE therapy, along with results from a small study showing continued benefit after discontinuation of long-term treatment, a larger study to assess its effect on markers of airway remodeling is underway.

Effect of bronchoconstriction on airway remodeling in asthma

BACKGROUND

Asthma is characterized pathologically by structural changes in the airway, termed airway remodeling. These changes are associated with worse long-term clinical outcomes and have been attributed to eosinophilic inflammation. In vitro studies indicate, however, that the compressive mechanical forces that arise during bronchoconstriction may induce remodeling independently of inflammation. We evaluated the influence of repeated experimentally induced bronchoconstriction on airway structural changes in patients with asthma.

METHODS

We randomly assigned 48 subjects with asthma to one of four inhalation challenge protocols involving a series of three challenges with one type of inhaled agent presented at 48-hour intervals. The two active challenges were with either a dust-mite allergen (which causes bronchoconstriction and eosinophilic inflammation) or methacholine (which causes bronchoconstriction without eosinophilic inflammation); the two control challenges (neither of which causes bronchoconstriction) were either saline alone or albuterol followed by methacholine (to control for nonbronchoconstrictor effects of methacholine). Bronchial-biopsy specimens were obtained before and 4 days after completion of the challenges.

RESULTS

Allergen and methacholine immediately induced similar levels of bronchoconstriction. Eosinophilic inflammation of the airways increased only in the allergen group, whereas both the allergen and the methacholine groups had significant airway remodeling not seen in the two control groups. Subepithelial collagen-band thickness increased by a median of 2.17 μm in the allergen group (interquartile range [IQR], 0.70 to 3.67) and 1.94 μm in the methacholine group (IQR, 0.37 to 3.24) (P<0.001 for the comparison of the two challenge groups with the two control groups); periodic acid-Schiff staining of epithelium (mucus glands) also increased, by a median of 2.17 percentage points in the allergen group (IQR, 1.03 to 4.77) and 2.13 percentage points in the methacholine group (IQR, 1.14 to 7.96) (P=0.003 for the comparison with controls). There were no significant differences between the allergen and methacholine groups.

CONCLUSIONS

Bronchoconstriction without additional inflammation induces airway remodeling in patients with asthma. These findings have potential implications for management.

Role of hyaluronan and hyaluronan-binding proteins in human asthma

BACKGROUND

The characteristics of human asthma are chronic inflammation and airway remodeling. Hyaluronan, a major extracellular matrix component, accumulates during inflammatory lung diseases, including asthma. Hyaluronan fragments stimulate macrophages to produce inflammatory cytokines. We hypothesized that hyaluronan and its receptors would play a role in human asthma.

OBJECTIVE

To investigate the role of hyaluronan and hyaluronan-binding proteins in human asthma.

METHODS

Twenty-one subjects with asthma and 25 healthy control subjects underwent bronchoscopy with endobronchial biopsy and bronchoalveolar lavage. Fibroblasts were cultured, and hyaluronan and hyaluronan synthase expression was determined at baseline and after exposure to several mediators relevant to asthma pathobiology. The expression of hyaluronan-binding proteins CD44, TLR (Toll-like receptor)-2, and TLR4 on bronchoalveolar lavage macrophages was determined by flow cytometry. IL-8 production by macrophages in response to hyaluronan fragment stimulation was compared.

RESULTS

Airway fibroblasts from patients with asthma produced significantly increased concentrations of lower-molecular-weight hyaluronan compared with those of normal fibroblasts. Hyaluronan synthase 2 mRNA was markedly increased in asthmatic fibroblasts. Asthmatic macrophages showed a decrease in cell surface CD44 expression and an increase in TLR2 and TLR4 expression. Macrophages from subjects with asthma showed an increase in responsiveness to low-molecular-weight hyaluronan stimulation, as demonstrated by increased IL-8 production.

CONCLUSION

Hyaluronan homeostasis is deranged in asthma, with increased production by fibroblasts and decreased CD44 expression on alveolar macrophages. Upregulation of TLR2 and TLR4 on macrophages with increased sensitivity to hyaluronan fragments suggests a novel proinflammatory mechanism by which persistence of hyaluronan fragments could contribute to chronic inflammation and airway remodeling in asthma.

Airway remodeling: a potential therapeutic target in asthma

BACKGROUND

Apart from airway inflammation, airway remodeling is one of the main pathological features of asthma. However, it remains unclear when airway remodeling starts in children and whether it could be a potential therapeutic target in asthma.

DATA SOURCES

We have reviewed the recent literature regarding structural changes after airway remodeling, the relationship between airway inflammation and airway remodeling, the relationship between childhood asthma and airway remodeling, and the role of long-term medication in asthma treatment for airway remodeling.

RESULTS

The relationship between airway inflammation and airway remodeling is still controversial. A number of morphological and pathological studies have confirmed that airway remodeling occurs not only in adult asthma, but also in childhood asthma. It develops early in the disease process of asthma. At present, long-term medication in asthma treatment mainly focuses on anti-inflammation. However, there are no therapeutic interventions that revert airway remodeling once it is established.

CONCLUSIONS

Airway remodeling may provide a possible new therapeutic target in the management of asthma. It is imperative to strengthen the research in developing new medications specifically for asthma airway remodeling. Prevention and treatment of airway remodeling become top priority in future asthma research.

Pharmacologic modulation of experimentally induced allergic asthma

Allergic asthma is the most frequent disease of the respiratory tract. The aim of the current experimental and clinical studies was to find new sources of drugs able to control asthmatic inflammation and airway hyperresponsiveness. Our experimental studies were focused on efficiency evaluation of substances able to influence activities of ion channels, phosphodiesterase (PDE) isoforms, substances from the group of polyphenols and NO metabolism modulators during experimentally induced allergic asthma.

Inactivation of capsaicin-sensitive nerves reduces pulmonary remodeling in guinea pigs with chronic allergic pulmonary inflammation

Pulmonary remodeling is an important feature of asthma physiopathology that can contribute to irreversible changes in lung function. Although neurokinins influence lung inflammation, their exact role in the extracellular matrix (ECM) remodeling remains to be determined. Our objective was to investigate whether inactivation of capsaicin-sensitive nerves modulates pulmonary ECM remodeling in animals with chronic lung inflammation. After 14 days of capsaicin (50 mg/kg, sc) or vehicle administration, male Hartley guinea pigs weighing 250-300 g were submitted to seven inhalations of increasing doses of ovalbumin (1, 2.5, and 5 mg/mL) or saline for 4 weeks. Seventy-two hours after the seventh inhalation, animals were anesthetized and mechanically ventilated and the lung mechanics and collagen and elastic fiber content in the airways, vessels and lung parenchyma were evaluated. Ovalbumin-exposed animals presented increasing collagen and elastic fiber content, respectively, in the airways (9.2 ± 0.9; 13.8 ± 1.2), vessels (19.8 ± 0.8; 13.4 ± 0.5) and lung parenchyma (9.2 ± 0.9; 13.8 ± 1.2) compared to control (P < 0.05). Capsaicin treatment reduced collagen and elastic fibers, respectively, in airways (1.7 ± 1.1; 7.9 ± 1.5), vessels (2.8 ± 1.1; 4.4 ± 1.1) and lung tissue (2.8 ± 1.1; 4.4 ± 1.1) of ovalbumin-exposed animals (P < 0.05). These findings were positively correlated with lung mechanical responses to antigenic challenge (P < 0.05). In conclusion, inactivation of capsaicin-sensitive nerve fibers reduces pulmonary remodeling, particularly collagen and elastic fibers, which contributes to the attenuation of pulmonary functional parameters.

Mepacrine treatment attenuates allergic airway remodeling segregated from airway inflammation in mice

Asthma is a chronic airway disease characterized by increased airway hyperresponsiveness, airway inflammation, and airway remodeling including collagen deposition in subepithelial regions. We have shown earlier that mepacrine has anti-inflammatory activity and decreased the features of airway remodeling in a subacute model of asthma, when administered during the inflammatory phase. But it was not clear whether the reduction of airway remodeling by mepacrine was a direct effect or indirectly related to the reduction in the airway inflammation. In this study, we determined the effect of mepacrine on airway remodeling and airway hyperresponsiveness (AHR) in a chronic model of asthma which showed the features of airway inflammation in the initial stage (inflammation predominant stage) and airway remodeling with mild airway inflammation in a later stage (remodeling predominant stage). Mepacrine was administered only in the later stage that more accurately simulates human asthma, where airway remodeling already exists at the time of diagnosis. The remodeling predominant stage was associated with high levels of Th2 cytokines like IL-4 and IL-13, increase in the levels of profibrotic mediators such as arginase and TGF-β, and increased collagen deposition. These were efficiently attenuated by mepacrine treatment and led to a significant reduction in AHR. Thus, we conclude from this study that mepacrine has direct effects on established airway remodeling independent of its anti-inflammatory effects.

Effects of pharmacological and non-pharmacological interventions

BACKGROUND

Asthma is recognised as a condition with variable airway obstruction with pathophysiological features that include activation of a wide range of inflammatory and structural cells. Additionally, structural changes in the airways have been demonstrated. This includes increased thickening of components in the basement membrane region, increased smooth muscle mass, increased vascularisation and many other events that is often referred to as remodelling of the airways. These processes and the underlying mechanisms have attracted considerable attention.

METHODS AND RESULTS

This review describes the different interventive approaches that have been tried in order to improve asthma control and affect the underlying pathophysiological pathways. These include elimination of harmful environmental and occupational exposures, a wide range of pharmacological agents as well as bronchial thermoplasty. The existing evidence for effects on airway inflammation and airway remodelling is discussed in relationship to mechanistic aspects and short- and long-term outcome.

CONCLUSION

It is expected that modulation of the asthmatic airway remodelling will become an even more important endpoint in the near future.

Relationship between matrix production by bronchial fibroblasts and lung function and AHR in asthma

The reasons for enhanced deposition of extracellular matrix in the airways of asthmatic patients and the subsequent consequences on lung function are uncertain. Here, we investigated the synthesis of procollagen I and proteoglycans, the activity of various metalloproteinases (MMPs) and the production of their inhibitor TIMP-1 in biopsy-derived bronchial fibroblasts from eight patients with stable mild-to-moderate asthma, and how they are related to patients' lung function and airway hyperreactivity (AHR). Following 24-h fibroblast incubation in 0.4% serum, procollagen I carboxyterminal propeptide (PICP), TIMP-1 and MMP-1 in cell media were analysed by ELISA, MMP-2, MMP-3, MMP-9 by zymography and total proteoglycan production by [(35)S]-sulphate-incorporation/ion chromatography. Patients' FEV(1)% predicted and methacholine log PD(20) negatively correlated with PICP synthesized by patients' bronchial fibroblasts (r = -0.74 and r = -0.71, respectively). PICP and proteoglycan amounts positively correlated (0.8 ≤ r ≤ 0.9) with MMP-2 and MMP-3 activity. A positive correlation (r = 0.75) was also found between proteoglycan production and TIMP-1. There was no correlation between MMP-9 activity and PICP or proteoglycan production. MMP-9 activity positively correlated with patients' FEV(1)% predicted (r = 0.97) and methacholine log PD(20) (r = 0.86), whereas negative associations (-0.6 ≤ r ≤ -0.7) were observed for MMP-2 and MMP-3. In stable mild-to-moderate asthma, increased procollagen I synthesis and activity of MMP-2 and MMP-3 in bronchial fibroblasts may negatively affect patients' lung function and AHR. In contrast, MMP-9 activity was not associated with procollagen or proteoglycan production, or worsening of patients' lung function and AHR. An enhanced production of procollagen I and proteoglycans might be a result of a negative feedback from their degradation by MMP-2 and MMP-3.

Optimal management of preschool asthma

Asthma is common in most parts of the world and remains the most common single reason preschool aged children are admitted to hospital in developed countries. In determining what the optimal management of preschool asthma is, several factors must be considered, including: the aims of treating preschool asthma; which children require treatment; and what treatment is effective. The most controversial aspects of treating preschool asthma relate to maintenance treatment. Guidelines for managing asthma in children have been developed; however, the relative lack of appropriate clinical trials in preschool children is a problem. Prolonged treatment with inhaled corticosteroids controls asthma during treatment but has no disease-modifying effects. Intermittent treatment with inhaled corticosteroids initiated at the onset of asthma-like symptoms and continued for short periods is ineffective. Short-term treatment with leukotriene receptor antagonists provides symptomatic relief but evidence for long-term efficacy is lacking. Further data are needed to determine optimal asthma management in preschool children.

Budesonide treatment of patients with collagenous colitis restores normal eosinophil and T-cell activity in the colon

BACKGROUND

The aim of this study was to assess the activity of eosinophils, neutrophils, and CD4+ as well as CD8+ T-cells in 11 patients with active collagenous colitis (CC) before and after 8 weeks of budesonide treatment (9 mg once daily) compared to 10 healthy individuals.

METHODS

Clinical symptoms were recorded and intestinal biopsy samples were taken and analyzed by flow cytometry. Eosinophils with a high surface expression of CD44 and low CD9 expression were classified as activated. Neutrophil activity was assessed by their expression of CD66b, and CD69 was used as an activation marker for T-cells.

RESULTS

All patients responded to the treatment. The eosinophils in active CC showed increased activity compared to controls. The activity was back to control levels after treatment. Neutrophils were not activated in CC patients before or after treatment. CD8+ T-cells from untreated CC patients had a lower activity than controls, and a tendency of lower activity was observed on CD4+ T-cells. After treatment, the activity was increased on both types of T-cells and was not different from controls.

CONCLUSIONS

In the present study we demonstrated that the inflammation in CC is characterized by activated eosinophils but there is no neutrophil activity. CD4+ and CD8+ T-cells are increased in numbers in active CC but, surprisingly, they had a lower grade of activity than in control subjects. The major finding of this study is that budesonide treatment restores the normal activation of eosinophils and T-cells, accompanied by clinical remission.

Protease inhibitors in respiratory disease: focus on asthma and chronic obstructive pulmonary disease

Respiratory diseases, such as asthma and chronic obstructive pulmonary disease (COPD), are a major health burden on society and current treatment modalities for these diseases have not significantly changed over the past 40 years. The only major pharmacological advancement for the treatment of these diseases has been to increase the duration of action of bronchodilators (asthma: salmeterol; COPD: tiotropium bromide) and glucocorticosteroids (asthma: fluticasone propionate) and, increasingly, to formulate these agents in the same delivery device. Despite our increasing understanding of the cell and molecular biology of these diseases, the development of novel treatments remains beyond the reach of the scientific community. Proteases are a family of proteins with diverse biological activity, which are found in abundance within the airways of asthma and COPD, and have been implicated in the pathogenesis of these diseases. The targeting of proteases, including mast cell tryptase, neutrophil elastase and matrix metalloprotease with low-molecular-weight inhibitors, has highlighted the potential role of these enzymes in mediating certain aspects of the disease process in preclinical studies. Several challenges remain regarding the development of protease inhibitors, including the synthesis of highly potent and specific inhibitors, and target validation in man.

Airway vascular reactivity and vascularisation in human chronic airway disease

Altered bronchial vascular reactivity and remodelling including angiogenesis are documented features of asthma and other chronic inflammatory airway diseases. Expansion of the bronchial vasculature under these conditions involves both functional (vasodilation, hyperperfusion, increased microvascular permeability, oedema formation, and inflammatory cell recruitment) and structural changes (tissue and vascular remodelling) in the airways. These changes in airway vascular reactivity and vascularisation have significant pathophysiological consequences, which are manifest in the clinical symptoms of airway disease. Airway vascular reactivity is regulated by a wide variety of neurotransmitters and inflammatory mediators. Similarly, multiple growth factors are implicated in airway angiogenesis, with vascular endothelial growth factor amongst the most important. Increasing attention is focused on the complex interplay between angiogenic growth factors, airway smooth muscle and the various collagen-derived fragments that exhibit anti-angiogenic properties. The balance of these dynamic influences in airway neovascularisation processes and their therapeutic implications is just beginning to be elucidated. In this review article, we provide an account of recent developments in the areas of vascular reactivity and airway angiogenesis in chronic airway diseases.

Effect of extracellular matrix composition on airway epithelial cell and fibroblast structure: implications for airway remodeling in asthma

BACKGROUND

Airway remodeling in asthma is characterized by structural changes to the airways including extracellular matrix (ECM) deposition and epithelial metaplasia. Extracellular matrix deposition in the subepithelial region may play an important role in modulation of epithelial cell and fibroblast structure and function because it lies in immediate contact with these cell types and exists within the functional epithelial mesenchymal trophic unit.

OBJECTIVE

To investigate the effect of aberrant ECM components on airway epithelial cells and fibroblasts and the relationship among subepithelial ECM deposition, other remodeling changes, and airway hyperresponsiveness.

METHODS

BEAS-2B human airway epithelial cells and WI-38 human airway fibroblast cells were cultured on various ECM protein substrates (Matrigel, representing normal basement membrane matrix, or aberrant matrix proteins collagen I, collagen III, and fibronectin). Airway remodeling changes were determined using morphometry in sections from a murine model of chronic allergic airway disease. Airway reactivity to methacholine was determined, and these parameters correlated.

RESULTS

Abnormal ECM substrates induced epithelial and fibroblast proliferation and altered the cell morphology of both human airway epithelial cells and fibroblasts when compared with normal basement membrane ECM. Subepithelial matrix deposition in the mouse correlated with epithelial thickness, but only weak correlations were noted among the other parameters.

CONCLUSIONS

We have demonstrated that ECM may affect the growth of airway epithelial cells and fibroblasts in vitro and may influence epithelial thickness in the mouse. These findings may have implications for understanding the pathogenesis of asthma and future therapeutic targeting of airway remodeling.

Animal models of airway inflammation and airway smooth muscle remodelling in asthma

Asthma is a complex disease that involves chronic inflammation and subsequent decline in airway function. The widespread use of animal models has greatly contributed to our understanding of the cellular and molecular pathways underlying human allergic asthma. Animal models of allergic asthma include smaller animal models which offer 'ease of use' and availability of reagents, and larger animal models that may be used to address aspects of allergic airways disease not possible in humans or smaller animal models. This review examines the application and suitability of various animal models for studying mechanisms of airway inflammation and tissue remodelling in allergic asthma, with a specific focus on airway smooth muscle.

TGF-beta1 induces human bronchial epithelial cell-to-mesenchymal transition in vitro

The subepithelial fibrosis component of airway remodeling in asthma is mediated through induction of transforming growth factor-beta1 (TGF-beta1) expression with consequent activation of myofibroblasts to produce extracellular matrix proteins. The number of myofibroblasts is increased in the asthmatic airway and is significantly correlated with the thickness of lamina reticularis. However, much is still unknown regarding the origin of bronchial myofibroblasts. Emerging evidence suggests that myofibroblasts can derive from epithelial cells by an epithelial-to-mesenchymal transition (EMT). In this study we investigated whether TGF-beta1 could induce bronchial epithelial EMT in the human bronchial epithelial cell. Cultured human bronchial epithelial cells, 16HBE-14o, were stimulated with 10 ng/ml TGF-beta1. Morphologic changes were observed and stress fiber by actin reorganization was detected by indirect immunostaining. The expression of alpha-SMA (alpha-smooth muscle actin) and the epithelial cell marker E-cadherin were detected in those 16HBE-14o cells after TGF-beta1 stimulation for 72 h, using immunostaining and RT-PCR. The contents of collagen I were determined by radioimmunoassay, and the levels of endogenous TGF-beta1 were measured with ELISA. Human bronchial epithelial cells stimulated with TGF-beta1 were converted from a "cobblestone" epithelial structure into an elongated fibroblast-like shape. Incubation of human bronchial epithelial cells with TGF-beta1 induced de novo expression of alpha-SMA, increased formation of stress fiber by F-actin reorganization, and loss of epithelial marker E-cadherin. Moreover, a significant increase in the levels of collagen I and endogenous TGF-beta1 released from bronchial epithelial cells stimulated with TGF-beta1 were observed. These results suggested that human bronchial epithelial cells, under stimulation of TGF-beta1, underwent transdifferentiation into myofibroblasts.

High-resolution computed tomography evaluation of airway distensibility in asthmatic and healthy subjects

PURPOSE

Airway-wall remodelling may result in reduced airway distensibility in bronchial asthma. This study evaluated the baseline airway calibre and distensibility in asthmatic patients by means of high-resolution computed tomography (HRCT).

MATERIALS AND METHODS

We studied seven patients (two men, age range 36-69 years) with chronic asthma [forced expiratory volume in the first second (FEV(1)) range: 30%-87% of predicted; FEV1/forced vital capacity (FVC) range 48%-75% of predicted) under stable clinical conditions and six healthy control subjects (three men, age range 29-50 years). In all subjects, HRCT scanning, at suspended end-expiratory volume, was performed at rest and during ventilation with 6 and 12 cmH(2)O by nasal insufflation with continuous positive airway pressure (nCPAP), both at baseline and after inhalation of 200 mug oxitropium bromide metered dose inhaler (MDI). External and lumen diameter (mm) of the right apical upper lobe bronchus were measured in all HRCT scans.

RESULTS

In asthmatics, 12 cmH(2)O insufflation significantly changed baseline lumen (3.3+/-0.7 mm vs. 3.8+/-0.6 mm; p<0.01) and external diameter (6.2+/-0.9 mm vs. 6.7+/-0.8 mm; p<0.05), whereas in healthy controls, both 6 and 12 cmH(2)O insufflation significantly changed baseline lumen diameter (4.0+/-1.6 mm vs. 4.8+/-1.6 mm and 4.7+/-1.7 mm; p<0.01). In asthmatic patients, oxitropium bromide inhalation significantly changed baseline lumen diameter (3.3+/-0.7 mm vs. 4.4+/-0.6 mm; p<0.05), whereas the application of 6 or 12 cmH(2)O insufflation did not modify any bronchial diameters. In healthy controls, oxitropium bromide inhalation significantly changed baseline lumen diameter (4.0+/-.6 mm vs. 5+/-1.5 mm; p<0.05). The application of 12 cmH(2)O but not of 6 cmH(2)O induced a significant change in lumen diameter (5.0+/-1.5 mm vs. 6,0+/-1.6 mm; p<0.05).

CONCLUSIONS

Our results show that airway distensibility in asthmatic patients, as assessed by HRCT, can differ compared with that of healthy controls. HRCT can provide useful information on airway distensibility.

MEN16132, a kinin B2 receptor antagonist, prevents the endogenous bradykinin effects in guinea-pig airways

Kinins have been suggested to be involved in human airway diseases such as asthma and rhinitis. MEN16132 is a non-peptide kinin B(2) receptor antagonist able to inhibit the responses produced by intravenous bradykinin into the airways, as bronchoconstriction and microvascular leakage; we tested the effect of MEN16132 on endogenously generated bradykinin through the dextran sulfate-induced contact activation of kinin-kallikrein cascade in guinea-pigs. After dextran sulfate administration (1.5 mg/kg i.v.), the pulmonary insufflation pressure was monitored and the microvascular leakage of upper and lower airways was assessed using Evans blue as tracer of plasma protein extravasation. Our results demonstrated that topical MEN16132 strongly inhibited the dextran sulfate-induced bronchoconstriction (0.3 mM solution aerosol for 5 min) and plasma protein extravasation in both lower airways (3-10 microM solution aerosol for 5 min) and nasal mucosa (0.3 nmol/nostril); Icatibant, the peptide antagonist of kinin B(2) receptor, exerted a 3-30-fold less potent inhibitory effect than MEN16132. We conclude that local application of MEN16132 into the airways abolishes the responses produced by the endogenous generation of bradykinin and it can be useful as new pharmacological tool to check the role of kinins in human diseases.

Indoor ultrafine particles and childhood asthma: exploring a potential public health concern

Exposure to airborne particulate matter has a negative effect on respiratory health in both children and adults. The ultrafine fraction of particulate air pollution is of particular interest because of its increased ability to cause oxidative stress and inflammation in the lungs. We reviewed the literature, and to date findings suggest that ultrafine particles (UFPs) may play an important role in triggering asthma symptoms. Furthermore, we believe that indoor UFP exposures may be particularly important because people spend the majority of their time indoors where sources of these contaminants are often present. While several epidemiological studies have examined the respiratory effects of ambient UFP exposures, the relationship between indoor UFP exposures and childhood asthma has yet to be examined in clinical or epidemiological studies. However, the portable instrumentation necessary to conduct such investigations is increasingly available, and we expect that this issue will be addressed in the near future. Therefore, the aim of this article is to provide a general review of UFP toxicity as related to childhood asthma in order to draw attention to a potentially important public health concern.

PRACTICAL IMPLICATIONS

A number of indoor sources of ultrafine particles (UFPs) have been identified, but the health effects of indoor UFP exposures remain largely unexplored. The potential respiratory effects of such exposures seem most concerning because these particles are known to cause oxidative stress and inflammation in the lungs. Subsequently, indoor UFP exposures may contribute to the exacerbation of asthma symptoms in susceptible individuals. This paper provides a review of UFP toxicity as related to childhood asthma, and to date evidence suggests that further investigation into the respiratory effects of indoor UFP exposures is warranted.

Eosinophils and CCR3 regulate interleukin-13 transgene-induced pulmonary remodeling

Interleukin (IL)-13 transgene overexpression in the lung induces features of chronic inflammatory lung disorders, including an eosinophil-rich inflammatory cell infiltration, airway hyper-reactivity, and remodeling of the airway (eg, subepithelial fibrosis, goblet cell metaplasia, and smooth muscle hypertrophy and hyperplasia). Here, we aimed to define the role of eosinophils and eosinophil signaling molecules [eg, eotaxins and CC chemokine receptor (CCR) 3] in IL-13-mediated airway disease. To accomplish this, we mated IL-13-inducible lung transgenic mice with mice deficient in eosinophil chemoattractant molecules (eotaxin-1, eotaxin-2, and their receptor CCR3) and with mice genetically deficient in eosinophils (Deltadbl-GATA). We report that in the absence of eotaxin-2 or CCR3, there was a profound reduction in IL-13-induced eosinophil recruitment into the lung lumen. In contrast, in the absence of eotaxin-1, there was a fourfold increase in IL-13-mediated eosinophil recruitment into the airway. IL-13 transgenic mice deficient in CCR3 had a 98% reduction in lung eosinophils. Furthermore, the reduction in pulmonary eosinophils correlated with attenuation in IL-13-induced mucus cell metaplasia and collagen deposition. Mechanistic analysis identified alterations in pulmonary protease and transforming growth factor-beta1 expression in eosinophil-deficient mice. Taken together, these data definitively identify a functional contribution by eosinophils on the effects of chronic IL-13 expression in the lung.

Steroids reduce local inflammatory mediator secretion and mucosal permeability in collagenous colitis patients

AIM: To study the effect of oral steroids upon clinical response and rectal mucosa secretion of eosinophil cationic protein (ECP), myeloperoxidase (MPO), basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF) and albumin in patients with collagenous colitis (CC).

METHODS: A segmental perfusion technique was used to collect perfusates from rectum of CC patients once before and twice (one and four weeks) after the start of steroid treatment. Clinical data was monitored and ECP, MPO, bFGF, VEGF and albumin concentrations were analyzed by immunochemical methods in perfusates and in serum.

RESULTS: Steroids reduced the number of bowel movements by more than five times within one week and all patients reported improved subjective well-being at wk 1 and 4. At the same time, the median concentrations of ECP, bFGF, VEGF and albumin in rectal perfusates decreased significantly. MPO values were above the detection limit in only 3 patients before treatment and in none during treatment. VEGF, bFGF, ECP and albumin concentrations correlated with each other with the exception of ECP and albumin. A decrease of serum ECP and VEGF concentrations was also seen even if the overtime reduction was not significant.

CONCLUSION: Oral steroid treatment in CC patients induced a simultaneous reduction of bowel movements and rectal release of ECP, bFGF, VEGF and albumin, suggesting that these polypeptides and increased mucosal permeability are important components of the pathophysiology in collagenous colitis.

A randomized clinical trial of peak flow versus symptom monitoring in older adults with asthma

OBJECTIVE

To determine whether peak flow monitoring has value above and beyond symptom monitoring when used as part of an asthma management plan.

METHODS

From a large managed-care organization, 296 adults, aged 50-92 yr, were recruited and randomly assigned in equal numbers to either use of symptoms or peak flow rate (twice daily or "as needed") for asthma monitoring, and monitored every 6 mo for 2 yr. Interventions were delivered in four 90-min small-group classes and included a personalized action plan and coaching in proper use of asthma inhalers.

RESULTS

We found no significant differences between peak flow rate and symptom monitoring, or between twice-daily and as-needed peak flow monitoring in the primary or secondary study outcomes: health care utilization (acute, nonacute, or total asthma visits), Asthma Quality-of-Life Questionnaire (AQLQ) scores, and lung function. AQLQ scores and prebronchodilator FEV1 increased significantly for both groups between baseline and 6 mo (AQLQ: mean, 0.4 units; 95% confidence interval, 0.3, 0.5; p < 0.0001; FEV1% predicted: mean, 4%). Inhaler technique improved substantially in both groups.

CONCLUSIONS

Peak flow monitoring has no advantage over symptom monitoring as an asthma management strategy for older adults with moderate-severe asthma when used in a comprehensive asthma management program. Improved outcomes in both groups suggest that understanding proper medication use, regular monitoring of asthma status, and understanding how to respond to changes are of primary importance.

Understanding the pathophysiology of severe asthma to generate new therapeutic opportunities

Although asthma is defined in terms of reversibility of airflow obstruction, as the disease becomes more severe and chronic, it adopts different characteristics, including a degree of fixed airflow obstruction and corticosteroid refractoriness. Underlying these phenotypes is evidence of airway wall remodeling, which should be distinguished from the increase in smooth muscle linked to airways hyperresponsiveness. Aberrant epithelial-mesenchymal communication leads to a chronic wound scenario, which is characterized by activation of the epithelial-mesenchymal trophic unit, epithelial damage, the laying down of new matrix, and greater involvement of neutrophils in the inflammatory response. In allergic asthmatic patients who remain symptomatic despite high-dose corticosteroid therapy, blockade of IgE with omalizumab confers appreciable clinical benefit. Chronic severe asthma is also accompanied by a marked increase in TNF-alpha production that might contribute to corticosteroid refractoriness. Based on this, TNF blockade with the soluble fusion protein entanercept produces improvement in asthma symptoms, lung function, and quality of life paralleled by a marked reduction in airways hyperresponsiveness. Identification of novel susceptibility genes, such as a disintegrin and metalloprotease 33 (ADAM33), will provide further targets against which to direct novel therapies for asthma, especially at the more severe end of the disease spectrum.

Airway smooth muscle excitation-contraction coupling and airway hyperresponsiveness

The primary complaints from patients with asthma pertain to function of airway smooth muscle (ASM) function including shortness of breath, wheezing, and coughing. Thus, it is imperative to better understand the mechanisms underlying excitation-contraction coupling in ASM. Here, we review the various signaling pathways underlying contraction in ASM, and then examine how these are altered in asthma and airway hyperresponsiveness (a hallmark feature of asthma). Throughout, we highlight how studies of vascular smooth muscle have helped or hindered progress in understanding ASM physiology and pathophysiology.

Inhaled corticosteroids and decline of lung function in community residents with asthma

BACKGROUND

Inhaled corticosteroids (ICS) constitute the cornerstone of treatment for asthma. Many studies have reported beneficial short term effects of these drugs, but there are few data on the long term effects of ICS on the decline in forced expiratory volume in 1 second (FEV(1)). This study was undertaken to determine whether adults with asthma treated with ICS have a less pronounced decline in FEV(1) than those not treated with ICS.

METHODS

Two hundred and thirty four asthmatic individuals from a longitudinal epidemiological study of the general population of Copenhagen, Denmark were divided into two groups; 44 were treated with ICS and 190 were not treated with ICS. The annual decline in FEV(1) was measured over a 10 year follow up period.

RESULTS

The decline in FEV(1) in the 44 patients receiving ICS was 25 ml/year compared with 51 ml/year in the 190 patients not receiving this treatment (p<0.001). The linear regression model with ICS as the variable of interest and sex, smoking, and wheezing as covariates showed that treatment with ICS was associated with a less steep decline in FEV(1) of 18 ml/year (p = 0.01). Adjustment for additional variables including age, socioeconomic status, body mass index, mucus hypersecretion, and use of other asthma medications did not change these results.

CONCLUSIONS

Treatment with ICS is associated with a significantly reduced decline in ventilatory function.

Prolonged ozone exposure in an allergic airway disease model: adaptation of airway responsiveness and airway remodeling

Background

Short-term exposure to high concentrations of ozone has been shown to increase airway hyper-responsiveness (AHR). Because the changes in AHR and airway inflammation and structure after chronic ozone exposure need to be determined, the goal of this study was to investigate these effects in a murine model of allergic airway disease.

Methods

We exposed BALB/c mice to 2 ppm ozone for 4, 8, and 12 weeks. We measured the enhanced pause (Penh) to methacholine and performed cell differentials in bronchoalveolar lavage fluid. We quantified the levels of IL-4 and IFN-γ in the supernatants of the bronchoalveolar lavage fluids using enzyme immunoassays, and examined the airway architecture under light and electron microscopy.

Results

The groups exposed to ozone for 4, 8, and 12 weeks demonstrated decreased Penh at methacholine concentrations of 12.5, 25, and 50 mg/ml, with a dose-response curve to the right of that for the filtered-air group. Neutrophils and eosinophils increased in the group exposed to ozone for 4 weeks compared to those in the filtered-air group. The ratio of IL-4 to INF-γ increased significantly after exposure to ozone for 8 and 12 weeks compared to the ratio for the filtered-air group. The numbers of goblet cells, myofibroblasts, and smooth muscle cells showed time-dependent increases in lung tissue sections from the groups exposed to ozone for 4, 8, and 12 weeks.

Conclusion

These findings demonstrate that the increase in AHR associated with the allergic airway does not persist during chronic ozone exposure, indicating that airway remodeling and adaptation following repeated exposure to air pollutants can provide protection against AHR.

Kinase inhibitors and airway inflammation

Kinases are believed to play a crucial role in the expression and activation of inflammatory mediators in the airway, in T-cell function and airway remodelling. Important kinases such as Inhibitor of kappaB kinase (IKK)2, mitogen activated protein (MAP) kinases and phsopho-inositol (PI)3 kinase regulate inflammation either through activation of pro-inflammatory transcription factors such as activating protein-1 (AP-1) and nuclear factor kappaB (NF-kappaB), which are activated in airway disease, or through regulation of mRNA half-life. Selective kinase inhibitors have been developed which reduce inflammation and some characteristics of disease in animal models. Targeting specific kinases that are overexpressed or over active in disease should allow for selective treatment of respiratory diseases. Interest in this area has intensified due to the success of the specific Abelson murine leukaemia viral oncogene (Abl) kinase inhibitor imatinib mesylate (Gleevec) in the treatment of chronic myelogenous leukaemia. Encouraging data from animal models and primary cells and early Phase I and II studies in other diseases suggest that inhibitors of p38 MAP kinase and IKK2 may prove to be useful novel therapies in the treatment of severe asthma, chronic obstructive pulmonary disease (COPD), cystic fibrosis and other inflammatory airway diseases.