Airway TGF-β1 and oxidant stress in children with severe asthma: association with airflow limitation

The Role of Transforming Growth Factor-β (TGF-β) in Asthma and Chronic Obstructive Pulmonary Disease (COPD)

Asthma and chronic obstructive pulmonary disease (COPD) represent chronic inflammatory respiratory disorders that, despite having distinct pathophysiological underpinnings, both feature airflow obstruction and respiratory symptoms. A critical component in the pathogenesis of each condition is the transforming growth factor-β (TGF-β), a multifunctional cytokine that exerts varying influences across these diseases. In asthma, TGF-β is significantly involved in airway remodeling, a key aspect marked by subepithelial fibrosis, hypertrophy of the smooth muscle, enhanced mucus production, and suppression of emphysema development. The cytokine facilitates collagen deposition and the proliferation of fibroblasts, which are crucial in the structural modifications within the airways. In contrast, the role of TGF-β in COPD is more ambiguous. It initially acts as a protective agent, fostering tissue repair and curbing inflammation. However, prolonged exposure to environmental factors such as cigarette smoke causes TGF-β signaling malfunction. Such dysregulation leads to abnormal tissue remodeling, marked by excessive collagen deposition, enlargement of airspaces, and, thus, accelerated development of emphysema. Additionally, TGF-β facilitates the epithelial-to-mesenchymal transition (EMT), a process contributing to the phenotypic alterations observed in COPD. A thorough comprehension of the multifaceted role of TGF-β in asthma and COPD is imperative for elaborating precise therapeutic interventions. We review several promising approaches that alter TGF-β signaling. Nevertheless, additional studies are essential to delineate further the specific mechanisms of TGF-β dysregulation and its potential therapeutic impacts in these chronic respiratory diseases.

Malondialdehyde as a Potential Oxidative Stress Marker for Allergy-Oriented Diseases: An Update

Malondialdehyde (MDA) is a compound that is derived from the peroxidation of polyunsaturated fatty acids. It has been used as a biomarker to measure oxidative stress in various biological samples in patients who are affected by a wide range of diseases. The aim of our work is to provide an updated overview of the role of MDA as a marker of oxidative stress in allergy-related diseases. We considered studies involving both paediatric and adult patients affected by rhinitis, asthma, urticaria and atopic dermatitis. The measurement of MDA was performed on different types of samples. The reported data highlight the role of serum MDA in inflammatory airway diseases. According to the literature review, the oxidative stress status in asthmatic patients, assessed via MDA determination, appears to worsen in the presence of other allergic airway diseases and in relation to the disease severity. This suggests that MDA can be a suitable marker for monitoring the disease status. However, there are several limitations in the considered studies due to the different samples used and the lack of phenotyping and description of the clinical period of patients examined. In cutaneous allergic diseases, the role of MDA is controversial because of the smallness of the studies and the heterogeneity of the samples and patients.

Relationship between Neutrophil Gelatinase-Associated Lipocalin, Eosinophil Cationic Protein, Cytokines, and Atopic Sensitization in Patients with Allergic Diseases

The effect of neutrophil gelatinase-associated lipocalin (NGAL) on eosinophil activation, atopic sensitization, and systemic inflammation in allergic diseases has rarely been investigated. This study aimed to investigate the relationship between NGAL, eosinophil cationic protein (ECP), cytokines, and allergen-specific immunoglobulin E (sIgE) in allergic diseases. A total of 136 patients with allergies and 58 healthy individuals were evaluated. The concentrations of NGAL, ECP, tumor necrosis factor-α (TNF-α), interleukin-5 (IL-5), sIgE, total IgE (tIgE), and high-sensitivity C-reactive protein (hsCRP) were measured. The transforming growth factor-β1 (TGF-β1) level was measured as a profibrotic marker of bronchial asthma. Allergic patients had significantly higher NGAL, ECP, and hsCRP levels than healthy individuals. However, there was no significant difference in NGAL levels between patients with positive and negative ECP tests and those with high and low sIgE scores. Asthmatic patients with elevated NGAL exhibited a significantly higher TGF-β1 level than those without elevated NGAL. However, no significant difference was observed in the ECP, IL-5, and sIgE levels between the two groups. Among the patients with a positive ECP test, subjects with elevated hsCRP had two times higher NGAL levels than those without elevated hsCRP. NGAL was positively correlated with TNF-α, TGF-β1, and hsCRP, but not with ECP, IL-5, tIgE, and sIgE. An elevated NGAL level led to a 1.3-fold increase in the prevalence of high TGF-β1 (odds ratio: 1.31; 95% CI: 1.04–2.58; P < 0.001). In conclusion, NGAL elevation may be more closely linked to allergic inflammation and a possible fibrotic change in the airways than to the severity of eosinophil activation and atopic sensitization.

Pathobiology of Airway Remodeling in Asthma: The Emerging Role of Integrins

Airway remodeling is a complex clinical feature of asthma that involves long-term disruption and modification of airway architecture, which contributes significantly to airway hyperresponsiveness (AHR) and lung function decline. It is characterized by thickening of the airway smooth muscle layer, deposition of a matrix below the airway epithelium, resulting in subepithelial fibrosis, changes within the airway epithelium, leading to disruption of the barrier, and excessive mucous production and angiogenesis within the airway wall. Airway remodeling contributes to stiffer and less compliant airways in asthma and leads to persistent, irreversible airflow obstruction. Current asthma treatments aim to reduce airway inflammation and exacerbations but none are targeted towards airway remodeling. Inhibiting the development of airway remodeling or reversing established remodeling has the potential to dramatically improve symptoms and disease burden in asthmatic patients. Integrins are a family of transmembrane heterodimeric proteins that serve as the primary receptors for extracellular matrix (ECM) components, mediating cell-cell and cell-ECM interactions to initiate intracellular signaling cascades. Cells present within the lungs, including structural and inflammatory cells, express a wide and varying range of integrin heterodimer combinations and permutations. Integrins are emerging as an important regulator of inflammation, repair, remodeling, and fibrosis in the lung, particularly in chronic lung diseases such as asthma. Here, we provide a comprehensive summary of the current state of knowledge on integrins in the asthmatic airway and how these integrins promote the remodeling process, and emphasize their potential involvement in airway disease.

Clinical Characteristics and Management Strategies for Adult Obese Asthma Patients

The rates of asthma and obesity are increasing concurrently in the United States. Epidemiologic studies demonstrate that the incidence of asthma increases with obesity. Furthermore, obese individuals have asthma that is more severe, harder to control, and resistant to standard medications. In fact, specific asthma-obesity phenotypes have been identified. Various pathophysiologic mechanisms, including mechanical, inflammatory, metabolic and microbiome-associated, are at play in promulgating the obese-asthma phenotypes. While standard asthma medications, such as inhaled corticosteroids and biologics, are currently used to treat obese asthmatics, they may have limited effectiveness. Targeting the underlying aberrant processes, such as addressing steroid resistance, microbiome, metabolic and weight loss approaches, may be helpful.

Respiratory syncytial virus persistent infection causes acquired CFTR dysfunction in human bronchial epithelial cells

OBJECTIVES

Many studies have shown that respiratory syncytial virus persistent infection may be the main cause of chronic respiratory pathology.However, the mechanism is unclear. Cystic fibrosis transmembrane conduction regulator (CFTR) is an apical membrane chloride channel, which is very important for the regulation of epithelial fluid, chloride ion, and bicarbonate transport. CFTR dysfunction will lead to changes in bronchial secretions and impair mucus clearance, which is related to airway inflammation. In our previous study, we observed the down-regulation of CFTR in airway epithelial cells in respiratory syncytial virus (RSV) infected mouse model. In this study, we further investigated the expression and function of CFTR by constructing an airway epithelial cell model of RSV persistent infection.

METHODS

16HBE14o- cells were infected with RSV at 0.01 multiplicity of infection (MOI). The expression of CFTR was detected by real-time RT-PCR, immunofluorescence, and Western blotting. The intracellular chloride concentration was measured by N-(ethoxycarbonylmethyl)-6-methoxyquinolium bromide (MQAE) and the chloride current was measured by whole-cell patch clamp recording.

RESULTS

16HBE14o- cells infected with RSV were survived to successive passages of the third generation (G3), while the expression and function of CFTR was progressively decreased upon RSV infection from the first generation (G1) to G3. Exposure of 16HBE14o- cells to RSV led to the gradual increase of TGF-β1 as well as phosphorylation of Smad2 following progressive RSV infection. Disruption of TGF-β1 signaling by SB431542 prevented Smad2 phosphorylation and rescued the expression of CFTR.

CONCLUSIONS

RSV infection can lead to defective CFTR function in airway epithelial cells, which may be mediated via activation of TGF-β1 signaling pathway.

Pediatric Obesity-Related Asthma: The Role of Nutrition and Nutrients in Prevention and Treatment

Childhood obesity rates have dramatically risen in numerous countries worldwide. Obesity is likely a factor in increased asthma risk, which is already one of the most widespread chronic respiratory pathologies. The pathogenic mechanism of asthma risk has still not yet been fully elucidated. Moreover, the role of obesity-related inflammation and pulmonary overreaction to environmental triggers, which ultimately result in asthma-like symptoms, and the importance of dietary characteristics is well recognized. Diet is an important adjustable element in the asthma development. Food-specific composition of the diet, in particular fat, sugar, and low-quality nutrients, is likely to promote the chronic inflammatory state seen in asthmatic patients with obesity. An unbalanced diet or supplementation as a way to control asthma more efficiently has been described. A personalized dietary intervention may improve respiratory symptoms and signs and therapeutic response. In this narrative review, we presented and discussed more recent literature on asthma associated with obesity among children, focusing on the risk of asthma among children with obesity, asthma as a result of obesity focusing on the role of adipose tissue as a mediator of systemic and local airway inflammation implicated in asthma regulation, and the impact of nutrition and nutrients in the development and treatment of asthma. Appropriate early nutritional intervention could possibly be critical in preventing and managing asthma associated with obesity among children.

Zhike Pingchuan Granule suppresses interleukin (IL)-6 or the medium of M2 macrophages induced apoptosis in human bronchial epithelial cells

The aim of this study was to explore the effects and action mechanism of Zhike Pingchuan Granule in human bronchial epithelial cells induced by IL-6 or the supernatant of M2. Upon IL-6 stimulation at different doses, Cell Counting Kit-8 (CCK8) assay and flow cytometry were, respectively, utilized to detect the cell viability and apoptosis levels of 16-HBE cells. ELISA and Western blot were, respectively, used to analyze the inflammatory markers and JAK2/STAT3 signals. Immunofluorescence assay was performed to identify M0 and M2 cells. As shown in results, ZKPC perturbed the expression of IL-6 inducible genes important for apoptosis, oxidative and inflammatory response, which was enhanced by JAK2 inhibitor. Besides the inhibitory effects on the phosphorylation levels of JAK2/STAT3, ZKPC markedly increased cell viability and reduced apoptosis in human bronchial epithelial cells (16-HBE) cultured in the supernatant of M2 cells. Collectively, ZKPC could inhibit the IL-6-induced JAK/STAT3 signaling cascade, increase cell viability and decrease apoptosis induced by the supernatant of M2. A more comprehensive understanding of the action mechanism of ZKPC on JAK2/STAT3 signaling pathway in human bronchial epithelial cells induced by IL-6 or M2 supernatant will enable ZKPC development in the control of asthma.

Molecular mechanisms of oxidative stress in asthma

The lungs are exposed to reactive oxygen species oxygen (ROS) produced as a result of inhalation of oxygen, as well as smoke and other air pollutants. Cell metabolism and the NADPH oxidases (Nox) generate low levels of intracellular ROS that act as signal transduction mediators by inducing oxidative modifications of histones, enzymes and transcription factors. Redox signalling is also regulated by localised production and sensing of ROS in mitochondria, the endoplasmic reticulum (ER) and inside the nucleus. Intracellular ROS are maintained at low levels through the action of a battery of enzymatic and non-enzymatic antioxidants. Asthma is a heterogeneous airway inflammatory disease with different immune endotypes; these include atopic or non-atopic Th2 type immune response associated with eosinophilia, or a non-Th2 response associated with neutrophilia. Airway remodelling and hyperresponsiveness accompany the inflammatory response in asthma. Over-production of ROS resulting from infiltrating immune cells, particularly eosinophils and neutrophils, and a concomitant impairment of antioxidant responses lead to development of oxidative stress in asthma. Oxidative stress is augmented in severe asthma and during exacerbations, as well as by air pollution and obesity, and causes oxidative damage of tissues promoting airway inflammation and hyperresponsiveness. Furthermore, deregulated Nox activity, mitochondrial dysfunction, ER stress and/or oxidative DNA damage, resulting from exposure to irritants, inflammatory mediators or obesity, may lead to redox-dependent changes in cell signalling. ROS play a central role in airway epithelium-mediated sensing, development of innate and adaptive immune responses, and airway remodelling and hyperresponsiveness. Nonetheless, antioxidant compounds have proven clinically ineffective as therapeutic agents for asthma, partly due to issues with stability and in vivo metabolism of these compounds. The compartmentalised nature of ROS production and sensing, and the role of ROS in homeostatic responses and in the action of corticosteroids and β2-adrenergic receptor agonists, adds another layer of complexity to antioxidant therapy development. Nox inhibitors and mitochondrial-targeted antioxidants are in clinical development for a number of diseases but they have not yet been investigated in asthma. A better understanding of the complex role of ROS in the pathogenesis of asthma will highlight new opportunities for more targeted and effective redox therapies.

Functional significance of 8-isoprostanes in sinonasal disease and asthma

BACKGROUND

The purpose of this study was to investigate how 8-isoprostanes, used as a marker of airway oxidative stress, were related to sinus disease and asthma.

METHODS

We analyzed samples and data from two separate studies, one investigating sinonasal disease in asthma, the other investigating the effect of BMI on airway disease. We measured airway (nasal lavage) 8-isoprostanes and investigated the relationship with measures of sinus and asthma symptoms, asthma control and lung function.

RESULTS

The study of people with sinonasal disease and poorly controlled asthma included 48 obese, 31 overweight and 23 lean participants. In multivariate analysis, nasal lavage 8-isoprostane levels increased with increasing BMI (p < 0.01), and were higher in Caucasian than African American participants (p = 0.01). Sinus symptoms were inversely related to nasal 8-isoprostanes (p = 0.02) independent of BMI and Race. In the study investigating the effect of BMI on airway disease, we enrolled 13 controls with obesity and 21 people with obesity and asthma: 8-isoprostane levels were higher in obese controls than in obese people with asthma (p < 0.01), and levels were inversely related to sinus symptoms (p = 0.02) and asthma control (p < 0.01).

INTERPRETATION

8-isoprostanes in nasal lavage are increased in obesity, and increased in Caucasians compared with African Americans. However, levels are higher in obese controls than obese people with asthma, and appear inversely related to symptoms of airway disease.

CLINICAL IMPLICATION

Airway 8-isoprostanes likely reflect complex oxidative signaling pathways, which are altered in obesity and those of different race, rather than being a simple marker of airway oxidative injury.

CAPSULE SUMMARY

Increased airway oxidative signaling (8-isoprostanes), may reflect normal physiology in the setting of obesity, as decreased levels are associated with disease activity in people with chronic sinonasal disease and asthma.

Ceramide in apoptosis and oxidative stress in allergic inflammation and asthma

BACKGROUND

Nothing is known about the mechanisms by which increased ceramide levels in the lung contribute to allergic responses and asthma severity.

OBJECTIVE

We sought to investigate the functional role of ceramide in mouse models of allergic airway disease that recapitulate the cardinal clinical features of human allergic asthma.

METHODS

Allergic airway disease was induced in mice by repeated intranasal administration of house dust mite or the fungal allergen Alternaria alternata. Processes that can be regulated by ceramide and are important for severity of allergic asthma were correlated with ceramide levels measured by mass spectrometry.

RESULTS

Both allergens induced massive pulmonary apoptosis and also significantly increased reactive oxygen species in the lung. Prevention of increases in lung ceramide levels mitigated allergen-induced apoptosis, reactive oxygen species, and neutrophil infiltration. In contrast, dietary supplementation of the antioxidant α-tocopherol decreased reactive oxygen species but had no significant effects on elevation of ceramide level or apoptosis, indicating that the increases in lung ceramide levels in allergen-challenged mice are not mediated by oxidative stress. Moreover, specific ceramide species were altered in bronchoalveolar lavage fluid from patients with severe asthma compared with in bronchoalveolar lavage fluid from individuals without asthma.

CONCLUSION

Our data suggest that elevation of ceramide level after allergen challenge contributes to the apoptosis, reactive oxygen species generation, and neutrophilic infiltrate that characterize the severe asthmatic phenotype. Ceramide might be the trigger of formation of Creola bodies found in the sputum of patients with severe asthma and could be a biomarker to optimize diagnosis and to monitor and improve clinical outcomes in this disease.

The Role of Macrophages in the Development of Acute and Chronic Inflammatory Lung Diseases

Macrophages play an important role in the innate and adaptive immune responses of organ systems, including the lungs, to particles and pathogens. Cumulative results show that macrophages contribute to the development and progression of acute or chronic inflammatory responses through the secretion of inflammatory cytokines/chemokines and the activation of transcription factors in the pathogenesis of inflammatory lung diseases, such as acute lung injury (ALI), acute respiratory distress syndrome (ARDS), ARDS related to COVID-19 (coronavirus disease 2019, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)), allergic asthma, chronic obstructive pulmonary disease (COPD), and idiopathic pulmonary fibrosis (IPF). This review summarizes the functions of macrophages and their associated underlying mechanisms in the development of ALI, ARDS, COVID-19-related ARDS, allergic asthma, COPD, and IPF and briefly introduces the acute and chronic experimental animal models. Thus, this review suggests an effective therapeutic approach that focuses on the regulation of macrophage function in the context of inflammatory lung diseases.

Oxidative stress and obesity-related asthma

Obesity is an asthma comorbidity associated with poor control, increased exacerbation risk and reduced response to inhaled and systemic corticosteroids. It affects children and adults differentially. In those with early onset asthma, it associated with increased eosinophilic inflammation, whereas in late onset, it correlates with lower nitric oxide (NO) and predominantly non-T2 inflammation. There are probably multiple pathways by which obesity impacts asthma; airway and systemic oxidative stress has been proposed as a mechanism that could potentially explain the obesity mediated increased comorbidity and poor response to treatment. More likely than not, oxidative stress is an epiphenomenon of a very diverse set of processes driven by complex changes in airway and systemic metabolism. This article provides a comprehensive overview of the clinical, metabolic, pathophysiological and therapeutic aspects of oxidative stress in patients with obesity and asthma.

TGF-β: The missing link in obesity-associated airway diseases?

Obesity is emerging as a global public health epidemic. The co-morbidities associated with obesity significantly contribute to reduced quality of life, mortality, and global healthcare burden. Compared to other asthma comorbidities, obesity prominently engenders susceptibility to inflammatory airway diseases such as asthma and chronic obstructive pulmonary disease (COPD), contributes to greater disease severity and evokes insensitivity to current therapies. Unlike in other metabolic diseases associated with obesity, the mechanistic link between obesity and airway diseases is only poorly defined. Transforming growth factor-β (TGF-β) is a pleiotropic inflammatory cytokine belonging to a family of growth factors with pivotal roles in asthma. In this review, we summarize the role of TGF-β in major obesity-associated co-morbidities to shed light on mechanisms of the diseases. Literature evidence shows that TGF-β mechanistically links many co-morbidities with obesity through its profibrotic, remodeling, and proinflammatory functions. We posit that TGF-β plays a similar mechanistic role in obesity-associated inflammatory airway diseases such as asthma and COPD. Concerning the role of TGF-β on metabolic effects of obesity, we posit that TGF-β has a similar mechanistic role in obesity-associated inflammatory airway diseases in interplay with different comorbidities such as hypertension, metabolic diseases like type 2 diabetes, and cardiomyopathies. Future studies in TGF-β-dependent mechanisms in obesity-associated inflammatory airway diseases will advance our understanding of obesity-induced asthma and help find novel therapeutic targets for prevention and treatment.

Ceruloplasmin and oxidative stress in severe eosinophilic asthma patients treated with Mepolizumab and Benralizumab

INTRODUCTION

Severe eosinophilic asthma has been associated with Th2 airway inflammation and elevated proinflammatory cytokines and chemokines, such as IL-5. Precision therapies have recently been shown to improve asthma symptoms with a steroid-sparing effect. Two such therapies, Benralizumab and Mepolizumab, humanized IgG antibodies directed against the IL-5 receptor and IL-5, have been approved for severe eosinophilic asthma.

METHODS

Here we used a differential proteomic approach to analyse serum from patients with severe eosinophilic asthma treated with Benralizumab and Mepolizumab in a search for differential molecular modifications responsible of their effects. Enrichment analysis of differential proteins was performed for the two treatments.

RESULTS AND DISCUSSION

After one month of Benralizumab treatment we detected up-regulation of certain protein species of the antioxidant ceruloplasmin. To investigate oxidative stress, we performed redox proteomics which detected lower oxidative burst after one month of Benralizumab treatment than in the pre-treatment phase or after one month of Mepolizumab therapy.

Subacute TGFβ Exposure Drives Airway Hyperresponsiveness in Cystic Fibrosis Mice through the PI3K Pathway

Cystic fibrosis (CF) is a lethal genetic disease characterized by progressive lung damage and airway obstruction. The majority of patients demonstrate airway hyperresponsiveness (AHR), which is associated with more rapid lung function decline. Recent studies in the neonatal CF pig demonstrated airway smooth muscle (ASM) dysfunction. These findings, combined with observed CF transmembrane conductance regulator (CFTR) expression in ASM, suggest that a fundamental defect in ASM function contributes to lung function decline in CF. One established driver of AHR and ASM dysfunction is transforming growth factor (TGF) β1, a genetic modifier of CF lung disease. Prior studies demonstrated that TGFβ exposure in CF mice drives features of CF lung disease, including goblet cell hyperplasia and abnormal lung mechanics. CF mice displayed aberrant responses to pulmonary TGFβ, with elevated PI3K signaling and greater increases in lung resistance compared with controls. Here, we show that TGFβ drives abnormalities in CF ASM structure and function through PI3K signaling that is enhanced in CFTR-deficient lungs. CF and non-CF mice were exposed intratracheally to an adenoviral vector containing the TGFβ1 cDNA, empty vector, or PBS only. We assessed methacholine-induced AHR, bronchodilator response, and ASM area in control and CF mice. Notably, CF mice demonstrated enhanced AHR and bronchodilator response with greater ASM area increases compared with non-CF mice. Furthermore, therapeutic inhibition of PI3K signaling mitigated the TGFβ-induced AHR and goblet cell hyperplasia in CF mice. These results highlight a latent AHR phenotype in CFTR deficiency that is enhanced through TGFβ-induced PI3K signaling.

Alternatively activated macrophages; a double-edged sword in allergic asthma

BACKGROUND

Macrophages are heterogenous phagocytic cells with an important role in the innate immunity. They are, also, significant contributors in the adaptive immune system. Macrophages are the most abundant immune cells in the lung during allergic asthma, which is the most common chronic respiratory disease of both adults and children. Macrophages activated by Th1 cells are known as M1 macrophages while those activated by IL-4 and IL-13 are called alternatively activated macrophages (AAM) or M2 cells. AAM are subdivided into four distinct subtypes (M2a, M2b, M2c and M2d), depending on the nature of inducing agent and the expressed markers. BODY: IL-4 is the major effector cytokine in both alternative activation of macrophages and pathogenesis of asthma. Thus, the role of M2a macrophages in asthma is a major concern. However, this is controversial. Therefore, further studies are required to improve our knowledge about the role of IL-4-induced macrophages in allergic asthma, through precisive elucidation of the roles of specific M2a proteins in the pathogenesis of asthma. In the current review, we try to illustrate the different functions of M2a macrophages (protective and pathogenic roles) in the pathogenesis of asthma, including explanation of how different M2a proteins and markers act during the pathogenesis of allergic asthma. These include surface markers, enzymes, secreted proteins, chemokines, cytokines, signal transduction proteins and transcription factors.

CONCLUSIONS

AAM is considered a double-edged sword in allergic asthma. Finally, we recommend further studies that focus on increased selective expression or suppression of protective and pathogenic M2a markers.

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.

Complement regulatory protein CD46 induces autophagy against oxidative stress-mediated apoptosis in normal and asthmatic airway epithelium

Autophagy plays a major role in defending against oxidative stress in respiratory epithelial cells. The complement regulatory protein CD46 can enhance autophagy and decrease local complement activation at sites of inflammation. This study investigated the mechanism by which CD46 protects against oxidative stress-mediated apoptosis in respiratory epithelium in asthmatic patients. Nasal mucosa samples were obtained from 60 adults with mild asthma who received turbinectomy and 30 controls. A decreased expression of CD46 and increased apoptosis were noted in the damaged nasal epithelium from the asthmatic patients. Primary epithelial cells cultured with Dermatophagoides pteronyssinus 2 showed decreased CD46 and increased cleaved CASPASE-3A expressions. Crosslinking CD46 mAb could induce the formation of autophagosomes and LC3-II expression in primary epithelial cells. CD46 engagement could induce autophagy against hydrogen peroxide-induced epithelial cell death, whereas the autophagy inhibitor 3-methyladenine decreased this effect. In addition, CD46 engagement decreased the expressions of PRO-IL-1β and NLRP3, enhanced the expression of scaffold protein GOPC, and diminished hydrogen peroxide-induced 8-OHdG, IL-1β and IL-6 production. Silencing ATG5 in human lung epithelial A549 cells decreased CD46-activated autophagy with LC3-II. CD46 induced autophagy and decreased the oxidative stress-mediated apoptosis of respiratory epithelium, and this may offer a new therapeutic strategy to treat asthma.

MFG-E8/integrin β3 signaling contributes to airway inflammation response and airway remodeling in an ovalbumin-induced murine model of asthma

Asthma is the most common chronic childhood disease worldwide, characterized by airway remodeling and chronic inflammation, orchestrated primarily by Th2 cytokines. The aim of the current study was to explore the influences of milk fat globule epidermal growth factor 8 (MFG-E8)/integrin β3 signaling involved in airway inflammation and remodeling in asthma. BALB/c mice were sensitized by intraperitoneal injection of ovalbumin (OVA), followed by OVA nebulization. The levels of MFG-E8 expression were declined markedly in the OVA-induced allergy murine model. In addition, administration of MFG-E8 strongly reduced the accumulation of T-helper type 2 (Th2)-associated cytokines (such as interleukin-4, -5, and -13) as well as chemokine CCL11 (eotaxin) in bronchoalveolar lavage fluid and tissues in the OVA-sensitized mice. Moreover, MFG-E8 remarkably repressed the total immunoglobulin E and OVA-specific immunoglobulin E in serum in OVA-challenged mice. Meanwhile, treatment with recombinant murine MFG-E8 noticeably prevented inflammatory cell infiltration into the airways, as showed by a marked decrease in the numbers of total immune cells, eosinophils, neutrophils, macrophages, and lymphocytes in the bronchoalveolar lavage fluid in response to OVA challenge. Importantly, MFG-E8 apparently alleviated OVA-driven airway remodeling, which were evidenced by declined secretion of important mediators of airway remodeling, including transforming growth factor-β1, matrix metalloproteinase 9, ADAM8, and vascular endothelial growth factor, and reduced airway collagen deposition and inhibited goblet cell hyperplasia in OVA-induced asthma in mice. Mechanistically, integrin 3 contributes to the protective effect of MFG-E8 in inhibiting airway inflammation and remodeling in OVA-driven features of allergic asthma. Overall, MFG-E8, as a candidate molecule to evaluate airway inflammation and remodeling, could be a potential target for the management and prevention of asthma exacerbations, suggesting that MFG-E8/integrin β3 signaling may serve as a promising therapeutic agent for childhood asthma.

MicroRNA-590-5p represses proliferation of human fetal airway smooth muscle cells by targeting signal transducer and activator of transcription 3

INTRODUCTION

Pediatric asthma has remained a health threat to children in recent years. The abnormal proliferation of airway smooth muscle (ASM) cells contributes to airway remodeling during development of asthma. MicroRNAs (miRNAs) are critical regulators of ASM cell proliferation during airway remodeling. miR-590-5p has been reported to regulate cell proliferation in various cell types. However, it remains unclear whether miR-590-5p regulates ASM cell proliferation. In this study, we aimed to investigate the potential role of miR-590-5p in regulating fetal ASM cell proliferation in vitro stimulated by platelet-derived growth factor (PDGF).

MATERIAL AND METHODS

miRNA, mRNA, and protein expression was detected by real-time quantitative polymerase chain reaction and western blot. Cell proliferation was detected by CCK-8 and BrdU assays. The target of miR-590-5p was confirmed by dual-luciferase reporter assay.

RESULTS

MiR-590-5p expression was significantly down-regulated in fetal ASM cells stimulated with PDGF (p < 0.05). Overexpression of miR-590-5p inhibited cell proliferation (p < 0.05), whereas the suppression of miR-590-5p promoted cell proliferation of fetal ASM cells stimulated with PDGF (p < 0.05). Signal transducer and activator of transcription 3 (STAT3) was identified as a target gene of miR-590-5p. In addition, miR-590-5p negatively regulated STAT3 expression (p < 0.05). Moreover, miR-590-5p also modulated downstream genes of STAT3 including cyclin D3 and p27 (p < 0.05). The restoration of STAT3 significantly reversed the inhibitory effect of miR-590-5p on fetal ASM cell proliferation.

CONCLUSIONS

MiR-590-5p inhibits proliferation of fetal ASM cells by down-regulating STAT3, thereby suggesting a novel therapeutic target for the treatment of pediatric asthma.

Chitotriosidase inhibits allergic asthmatic airways via regulation of TGF-β expression and Foxp3+ Treg cells

BACKGROUND

Chitotriosidase (chitinase 1, Chit1), a major true chitinase in humans, is induced in childhood asthma and has been implicated in the pathogenesis of a variety of inflammatory and tissue remodeling responses. However, the role and the mechanisms that underlie these contributions to the diseases have not been defined. We hypothesized that Chit1 plays a significant role in the pathogenesis of allergic asthma.

METHODS

Wild-type and Chit1-deficient mice and cells in culture were used to define the roles of Chit1 in models of allergic adaptive Th2 inflammation. In addition, the levels of sputum Chit1 were evaluated in pediatric asthma patients and compared to control.

RESULTS

The levels of sputum Chit1 were significantly increased in the patients with childhood asthma. Mice with Chit1 null mutation demonstrated enhanced allergic Th2 inflammatory and cytokine and IgE responses to OVA or house dust mite allergen sensitization and challenge. However, the expression levels of TGF-β1 were significantly decreased with a diminished number of Foxp3+ regulatory T cells (Treg) in the lungs of Chit1-/- mice compared to WT controls. In vitro, the absence of Chit1 significantly reduced TGF-β-stimulated conversion of CD4+ CD25- naïve T cells to CD4+ Foxp3+ Treg cells, suggesting Chit1 is required for optimal effect of TGF-β1 in Treg cell differentiation.

CONCLUSION

Chit1 plays a protective role in the pathogenesis of allergic inflammation and asthmatic airway responses via regulation of TGF-β expression and Foxp3+ Treg cells.

TGF-β1 Evokes Human Airway Smooth Muscle Cell Shortening and Hyperresponsiveness via Smad3

Transforming growth factor β1 (TGF-β1), a cytokine whose levels are elevated in the airways of patients with asthma, perpetuates airway inflammation and modulates airway structural cell remodeling. However, the role of TGF-β1 in excessive airway narrowing in asthma, or airway hyperresponsiveness (AHR), remains unclear. In this study, we set out to investigate the direct effects of TGF-β1 on human airway smooth muscle (HASM) cell shortening and hyperresponsiveness. The dynamics of AHR and single-cell excitation-contraction coupling were measured in human precision-cut lung slices and in isolated HASM cells using supravital microscopy and magnetic twisting cytometry, respectively. In human precision-cut lung slices, overnight treatment with TGF-β1 significantly augmented basal and carbachol-induced bronchoconstriction. In isolated HASM cells, TGF-β1 increased basal and methacholine-induced cytoskeletal stiffness in a dose- and time-dependent manner. TGF-β1-induced single-cell contraction was corroborated by concomitant increases in myosin light chain and myosin phosphatase target subunit 1 phosphorylation levels, which were attenuated by small interfering RNA-mediated knockdown of Smad3 and pharmacological inhibition of Rho kinase. Strikingly, these physiological effects of TGF-β1 occurred through a RhoA-independent mechanism, with little effect on HASM cell [Ca2+]i levels. Together, our data suggest that TGF-β1 enhances HASM excitation-contraction coupling pathways to induce HASM cell shortening and hyperresponsiveness. These findings reveal a potential link between airway injury-repair responses and bronchial hyperreactivity in asthma, and define TGF-β1 signaling as a potential target to reduce AHR in asthma.

TGF-β1 Suppresses the Type I IFN Response and Induces Mitochondrial Dysfunction in Alveolar Macrophages

TGF-β1 is a pleiotropic cytokine with an established role in fibrosis; however, the immunosuppressive effects of TGF-β1 are less characterized. Elevated levels of TGF-β1 are found in patients with acute and chronic lung diseases, and the underlying disease processes are exacerbated by respiratory viral infections. The alveolar macrophage is the first line of cellular defense against respiratory viral infections, and its response to infections is dependent on environmental cues. Using the mouse alveolar macrophage line, MH-S, and human CD14⁺ monocyte-derived macrophages, we examined the effects of TGF-β1 on the type I IFN antiviral response, macrophage polarization, and mitochondrial bioenergetics following a challenge with human respiratory syncytial virus (RSV). Our results showed that TGF-β1 treatment of macrophages decreased the antiviral and proinflammatory response, and suppressed basal, maximal, spare mitochondrial respiration, and mitochondrial ATP production. Challenge with RSV following TGF-β1 treatment further exacerbated mitochondrial dysfunction. The TGF-β1 and TGF-β1+RSV-treated macrophages had a higher frequency of apoptosis and diminished phagocytic capacity, potentially through mitochondrial stress. Disruption of TGF-β1 signaling or rescue of mitochondrial respiration may be novel therapeutically targetable pathways to improve macrophage function and prevent secondary bacterial infections that complicate viral respiratory infections.

Overexpression of microRNA-375 impedes platelet-derived growth factor-induced proliferation and migration of human fetal airway smooth muscle cells by targeting Janus kinase 2

The abnormal proliferation and migration of airway smooth muscle (ASM) cells play a critical role in airway remodeling during the development of asthma. MicroRNAs (miRNAs) have emerged as critical regulators of ASM cell proliferation and migration in airway remodeling. In this study, we aimed to investigate the potential role of miR-375 in the regulation of platelet-derived growth factor (PDGF)-induced fetal ASM cell proliferation and migration. Our results showed that miR-375 expression was significantly decreased in fetal ASM cells that were treated with PDGF. Functional data showed that overexpression of miR-375 inhibited the proliferation and migration of fetal ASM cells, whereas inhibition of miR-375 enhanced the proliferation and migration of fetal ASM cells. The results of bioinformatics analysis and a dual-luciferase reporter assay showed that miR-375 binds directly to the 3'-untranslated region of Janus kinase 2 (JAK2). Further data confirmed that miR-375 negatively regulates the expression of JAK2 in fetal ASM cells. Moreover, miR-375 also impeded the PDGF-induced activation of signal transducer and activator of transcription 3 (STAT3) in fetal ASM cells. However, restoration of JAK2 expression partially reversed the inhibitory effect of miR-375 on fetal ASM cell proliferation and migration. Overall, our results demonstrate that miR-375 inhibits fetal ASM cell proliferation and migration by targeting JAK2/STAT3 signaling. Our study provides a potential therapeutic target for the development of novel treatment strategies for pediatric asthma.

In the Shadow of Fibrosis: Innate Immune Suppression Mediated by Transforming Growth Factor-β

Transforming growth factor-β (TGFB) regulates cell proliferation, differentiation, apoptosis, and matrix homeostasis and is intimately involved in fibrosis. TGFB expression is increased in fibrotic lung diseases, such as idiopathic pulmonary fibrosis, and in chronic inflammatory conditions, such as chronic obstructive pulmonary disease and asthma. In addition to exhibiting profibrotic activities, the protein exhibits profound immune-suppressive actions involving both innate and adaptive responses, but often this aspect of TGFB biology is overlooked. Recent investigations have demonstrated that TGFB causes wide-ranging immune suppression, including blunting of pivotal early innate IFN responses. These activities permit severe virus infections, often followed by secondary bacterial infections, which may last longer, with augmented inflammation, scarring, fibrosis, and loss of lung function. Strategies to oppose TGFB actions or to enhance IFN responses may help ameliorate the detrimental consequences of infection in patients with diseases characterized by TGFB overexpression, inflammation, and fibrosis.

Thymic stromal lymphopoietin and apocynin alter the expression of airway remodeling factors in human rhinovirus-infected cells

Airway remodeling is a characteristic of bronchial asthma. The process involves the expression of many genes, such as transforming growth factor-beta (TGF-β), tissue inhibitors of metalloproteinases (TIMP-1), MMP and arginase. Human rhinovirus (HRV) is known to cause asthma exacerbations, and viral infections might be involved in the development of airway remodeling. Therefore, the aim of this study was to determine the influence of HRV on the genes involved in airway remodeling and to examine the impact of thymic stromal lymphopoietin (TSLP) and contribution of oxidative stress on airway remodeling in the context of HRV infection. Peripheral blood mononuclear cells, isolated from blood collected from 10 healthy volunteers, and human lung fibroblasts were infected with HRV-16. The cells were treated with apocynin or TSLP 48h after infection. The expression of TGF-β1, TIMP-1 and arginase I mRNA and protein were determined by real-time PCR, immunoblotting and ELISA, respectively. Rhinovirus infection significantly increased the expression of TGF-β1 and arginase I, on the mRNA and protein levels. This effect was inhibited by apocynin, though only on the mRNA level. TIMP-1 expression was not influenced by HRV; however, apocynin caused a significant increase of TIMP-1 mRNA expression. TSLP increased the expression of TGF-β1 and arginase I mRNA in fibroblasts, but not in PBMC.

MiR-23b controls TGF-β1 induced airway smooth muscle cell proliferation via direct targeting of Smad3

BACKGROUND

MicroRNAs are small yet versatile gene tuners that regulate a variety of cellular processes, including cell growth and proliferation. Here we report that miR-23b inhibited airway smooth muscle cells (ASMCs) proliferation through directly targeting of Smad3.

METHODS

We obtained ASMCs by laser capture microdissection of normal and asthmatic mice lung tissues. Mice ASMCs were cultured and induced by TGF-β1. The implication between TGF-β1 and miR-23b in ASMCs were detected by RT-PCR. The effects of miR-23b on ASMCs proliferation and apoptosis were assessed by transient transfection of miR-23b mimics and inhibitor. The expression of Smad3 in ASMCs were detected by RT-PCR and Western blotting analysis. Dual-Luciferase Reporter Assay System will be applied to identify whether Smad3 is a target gene of miR-23b.

RESULTS

TGF-β1 and miR-23b mRNA expression of in-situ bronchial ASMCs collected by laser capture microdissection were increased in asthmatic mice compared to non-asthma controls. This is accompanied by an increase in miR-23b mRNA expression in TGF-β1 induced ASMCs. miR-23b up-regulation significantly inhibited TGF-β1-induced ASMCs proliferation and promoted apoptosis. MiR-23b negatively regulates the expression of Smad3 in ASMCs. Dual-Luciferase Reporter Assay System demonstrated that Smad3 was a direct target of miR-23b.

CONCLUSIONS

MiR-23b may function as an inhibitor of asthma airway remodeling by suppressing ASMCs proliferation via direct targeting of Smad3.

Severe Asthma in Children: Lessons Learned and Future Directions

Severe asthma in children is a complicated and heterogeneous disorder that is extremely challenging to treat. Although most children with asthma derive clinical benefit from daily administration of low-to-medium-dose inhaled corticosteroid (ICS) therapy, a small subset of children with "severe" or "refractory" asthma require high doses of ICS and even systemic corticosteroids to maintain symptom control. These children with severe asthma are at increased risk for adverse outcomes including medication-related side effects and recurrent and life-threatening exacerbations that significantly impair quality of life. This review highlights findings on severe asthma in school-age children (age 6-17 years) from the National Heart, Lung and Blood Institute's Severe Asthma Research Program (SARP) over a 10-year period, between 2001 and 2011. Although SARP has advanced knowledge of the unique clinical, biological, and molecular attributes of severe asthma in children, considerable gaps remain for which additional studies are needed.

MiR-143-3p controls TGF-β1-induced cell proliferation and extracellular matrix production in airway smooth muscle via negative regulation of the nuclear factor of activated T cells 1

MicroRNAs (miRNAs) are small noncoding RNAs that function in diverse biological processes. However, little is known about the precise role of microRNAs in the functioning of airway smooth muscle cells (ASMCs). Here, we investigated the potential role and mechanisms of the miR-143 -3p on proliferation and the extracellular matrix (ECM) protein production of ASMCs. We demonstrated that miR-143-3p was aberrantly lower in ASMCs isolated from individuals with asthma than in individuals without asthma. Meanwhile, TGF-β1 caused a marked decrease in a time-dependent manner in miR-143-3p expression in ASMCs from asthmatics. Additionally, the overexpression of miR- 143-3p robustly reduced TGF-β1-induced ASMCs proliferation and downregulated CDK and cyclin expression, whereas the inhibition of miR-143-3p significantly enhanced ASMCs proliferation and upregulated the level of CDKs and cyclins. Re-expression of miR-143-3p attenuated ECM protein deposition reflected as a marked decrease in the expression of type I collagen and fibronectin, whereas miR-143-3p downregulation caused an opposite effect on the expression of type I collagen and fibronectin. Moreover, qRT-PCR and western blot analysis indicated that miR-143-3p negatively regulated the expression of nuclear factor of activated T cells 1 (NFATc1). Subsequent analyses demonstrated that NFATc1 was a direct and functional target of miR-143-3p, which was validated by the dual luciferase reporter assay. Most importantly, the overexpression of NFATc1 effectively reversed the inhibition of miR-143-3p on TGF-β1-induced proliferation, and strikingly abrogated the effect of miR-143-3p on the expression of CDK4 and Cyclin D1. Together, miR-143-3p may function as an inhibitor of asthma airway remodeling by suppressing proliferation and ECM protein deposition in TGF-β1-mediated ASMCs via the negative regulation of NFATc1 signaling, suggesting miR-143-3p as a potential therapeutic target for asthma.

Molecular Background of miRNA Role in Asthma and COPD: An Updated Insight

Inflammatory airway diseases are a significant health problems requiring new approaches to the existing therapies and addressing fundamental issues. Difficulties in developing effective therapeutic strategies might be caused by lack of understanding of their exact molecular mechanism. MicroRNAs (miRNAs) are a class of regulators that already revolutionized the view of gene expression regulation. A cumulating number of investigations show a pivotal role of miRNAs in the pathogenesis of asthma, chronic obstructive pulmonary disease (COPD), or airway remodeling through the regulation of many pathways involved in their pathogenesis. Expression changes of several miRNAs have also been found to play a role in the development and/or improvement in asthma or COPD. Still, relatively little is known about the role of miRNAs in inflammatory disorders. The microRNA profiles may differ depending on the cell type or antigen-presenting cell. Based on the newest literature, this review discusses the current knowledge concerning miRNA contribution and influence on lung inflammation and chosen inflammatory airway diseases: asthma and COPD.

Immunization against TGF-β1 reduces collagen deposition but increases sustained inflammation in a murine asthma model

Transforming growth factor (TGF)-β1 is involved in the processes of airway inflammation and remodeling; however, its reported roles in asthma pathogenesis are controversial. We sought both to investigate the effects of active immunization targeting TGF-β1 on allergen-induced airway inflammatory responses and to evaluate its possible application for asthma treatment. BALB/c mice were immunized with a virus-like-particle (VLP) vaccine presenting a TGF-β1 peptide. For the preventive intervention of acute allergic airway inflammation, immunization was conducted before sensitization and challenges with ovalbumin (OVA), and for the therapeutic treatment of chronic inflammatory responses, immunization was initiated after inflammatory responses were established. Preventive immunization with VLPs led to increased proinflammatory IL-4, IL-13, and IL-33 levels in the bronchoalveolar lavage fluids (BALF) with no significant effects on lung tissue inflammation and airway goblet cell hyperplasia. Therapeutic treatment showed that at 24 h after the fourth 2-day challenge with OVA following 2 intraperitoneal sensitizations, airway subepithelial collagen deposition was significantly ameliorated in vaccinated mice, whereas the lung histology and cytokine profile in the BALF were not changed. In contrast, after a 4-week recovery from the last OVA challenge, the vaccinated mice's collagen deposition remained reduced, but they sustained lung-tissue inflammation and goblet-cell hyperplasia; elevated IL-13, TNF, and IFN-γ levels in the BALF; and increased airway resistance, tissue resistance, and tissue elastance. In a conclusion, the role of TGF-β1 is complicated in allergic airway inflammatory responses. It is important to make a careful assessment in accordance with specific disease conditions when targeting TGF-β1 for a therapeutic purpose.

Sinomenine attenuates airway inflammation and remodeling in a mouse model of asthma

Asthma is an inflammatory disease that involves airway inflammation and remodeling. Sinomenine (SIN) has been demonstrated to have immunosuppressive and anti-inflammatory properties. The aim of the present study was to investigate the inhibitory effects of SIN on airway inflammation and remodeling in an asthma mouse model and observe the effects of SIN on the transforming growth factor-β1 (TGF-β1)/connective tissue growth factor (CTGF) pathway and oxidative stress. Female BALB/c mice were sensitized by repetitive ovalbumin (OVA) challenge for 6 weeks in order to develop a mouse model of asthma. OVA-sensitized animals received SIN (25, 50 and 75 mg/kg) or dexamethasone (2 mg/kg). A blank control group received saline only. The area of smooth muscle and collagen, levels of mucus secretion and inflammatory cell infiltration were evaluated 24 h subsequent to the final OVA challenge. mRNA and protein levels of TGF-β1 and CTGF were determined by reverse transcription-quantitative polymerase chain reaction and immunohistology, respectively. The indicators of oxidative stress were detected by spectrophotometry. SIN significantly reduced allergen-induced increases in smooth muscle thickness, mucous gland hypertrophy, goblet cell hyperplasia, collagen deposition and eosinophilic inflammation. The levels of TGF-β1 and CTGF mRNA and protein were significantly reduced in the lungs of mice treated with SIN. Additionally, the total antioxidant capacity was increased in lungs following treatment with SIN. The malondialdehyde content and myeloperoxidase activities in the lungs from OVA-sensitized mice were significantly inhibited by SIN. In conclusion, SIN may inhibit airway inflammation and remodeling in asthma mouse models, and may have therapeutic efficacy in the treatment of asthma.

Severe asthma in school-age children: evaluation and phenotypic advances

Although the majority of children with asthma have a favorable clinical response to treatment with low to moderate doses of inhaled corticosteroids (ICS), a small subset of children have "severe" asthma characterized by ongoing symptoms and airway inflammation despite treatment with high doses of ICS and even oral corticosteroids. Although there is symptom heterogeneity in the affected children, children with severe asthma share the risk for adverse outcomes, including recurrent and potentially life-threatening exacerbations, which contribute to substantial economic burden. This article reviews current knowledge of severe asthma in school-age children (age 6-17 years) with a focus on recent literature published after January 2012. Clinical management approaches for children with severe asthma are discussed as well as current phenotyping efforts and emerging phenotypic-directed therapies that may be of benefit for subpopulations of children with severe asthma in the future.

Increased epidermal growth factor in nasopharyngeal aspirates from infants with recurrent wheeze

Airway remodeling is known to be a consequence of repeated injury and thought to be involved in early stage of asthma. We aimed to investigate the mediators associated with airway remodeling in recurrent early wheezers. Thirty-three infants, aged 2 years or less, admitted with exacerbation of wheezing were enrolled. All of them had experienced three or more episodes of wheezing before admission. They were categorized into two groups: those who had been hospitalized two or more times for severe wheezing (N = 19) and those who had only once or never been hospitalized (N = 14). Epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), and transforming growth factor (TGF)-β1 levels in nasopharyngeal aspirates (NPA) collected on admission were measured. The difference between two patients groups divided based on their hospitalization history was assessed. We also examined these mediators in older asthmatic children (N = 15) admitted with exacerbation and their relationship with lung function parameters measured after stabilization. NPA EGF levels were significantly increased in recurrent early wheezers compared to controls. EGF, VEGF, and TGF-β1 levels were significantly higher in those with a previous history of multiple hospitalizations than in those without. In older asthmatic children, EGF levels were related with age and duration of asthma, but showed an inverse correlation with forced expiratory volume in 1 sec and forced expiratory flow between 25% and 75% of vital capacity. Our study shows that there might be significant damage during exacerbation in wheezy infants as levels of the mediators, EGF, VEGF, and TGF-β1 were higher in those who had been frequently hospitalized. It seems to suggest that those infants with severe recurrent wheezing might have chronic airway obstruction.

Vitamin D attenuates cytokine-induced remodeling in human fetal airway smooth muscle cells

Asthma in the pediatric population remains a significant contributor to morbidity and increasing healthcare costs. Vitamin D3 insufficiency and deficiency have been associated with development of asthma. Recent studies in models of adult airway diseases suggest that the bioactive Vitamin D3 metabolite, calcitriol (1,25-dihydroxyvitamin D3 ; 1,25(OH)2 D3 ), modulates responses to inflammation; however, this concept has not been explored in developing airways in the context of pediatric asthma. We used human fetal airway smooth muscle (ASM) cells as a model of the early postnatal airway to explore how calcitriol modulates remodeling induced by pro-inflammatory cytokines. Cells were pre-treated with calcitriol and then exposed to TNFα or TGFβ for up to 72 h. Matrix metalloproteinase (MMP) activity, production of extracellular matrix (ECM), and cell proliferation were assessed. Calcitriol attenuated TNFα enhancement of MMP-9 expression and activity. Additionally, calcitriol attenuated TNFα and TGFβ-induced collagen III expression and deposition, and separately, inhibited proliferation of fetal ASM cells induced by either inflammatory mediator. Analysis of signaling pathways suggested that calcitriol effects in fetal ASM involve ERK signaling, but not other major inflammatory pathways. Overall, our data demonstrate that calcitriol can blunt multiple effects of TNFα and TGFβ in developing airway, and point to a potentially novel approach to alleviating structural changes in inflammatory airway diseases of childhood.

Severe asthma in children

Severe asthma in children is characterized by sustained symptoms despite treatment with high doses of inhaled corticosteroids or oral corticosteroids. Children with severe asthma may fall into 2 categories, difficult-to-treat asthma or severe therapy-resistant asthma. Difficult-to-treat asthma is defined as poor control due to an incorrect diagnosis or comorbidities, or poor adherence due to adverse psychological or environmental factors. In contrast, treatment resistant is defined as difficult asthma despite management of these factors. It is increasingly recognized that severe asthma is a highly heterogeneous disorder associated with a number of clinical and inflammatory phenotypes that have been described in children with severe asthma. Guideline-based drug therapy of severe childhood asthma is based primarily on extrapolated data from adult studies. The recommendation is that children with severe asthma be treated with higher-dose inhaled or oral corticosteroids combined with long-acting β-agonists and other add-on therapies, such as antileukotrienes and methylxanthines. It is important to identify and address the influences that make asthma difficult to control, including reviewing the diagnosis and removing causal or aggravating factors. Better definition of the phenotypes and better targeting of therapy based upon individual patient phenotypes is likely to improve asthma treatment in the future.

Cysteine oxidation impairs systemic glucocorticoid responsiveness in children with difficult-to-treat asthma

BACKGROUND

The mechanisms underlying glucocorticoid responsiveness are largely unknown. Although redox regulation of the glucocorticoid receptor (GR) has been reported, it has not been studied in asthmatic patients.

OBJECTIVE

We characterized systemic cysteine oxidation and its association with inflammatory and clinical features in healthy children and children with difficult-to-treat asthma. We hypothesized that cysteine oxidation would be associated with increased markers of oxidative stress and inflammation, increased features of asthma severity, decreased clinically defined glucocorticoid responsiveness, and impaired GR function.

METHODS

PBMCs were collected from healthy children (n = 16) and children with asthma (n = 118) aged 6 to 17 years. Children with difficult-to-treat asthma underwent glucocorticoid responsiveness testing with intramuscular triamcinolone. Cysteine, cystine, and inflammatory chemokines and reactive oxygen species generation were quantified, and expression and activity of the GR were assessed.

RESULTS

Cysteine oxidation was present in children with difficult-to-treat asthma and accompanied by increased reactive oxygen species generation and increased CCL3 and CXCL1 mRNA expression. Children with the greatest extent of cysteine oxidation had more features of asthma severity, including poorer symptom control, greater medication use, and less glucocorticoid responsiveness despite inhaled glucocorticoid therapy. Cysteine oxidation also modified the GR protein by decreasing available sulfhydryl groups and decreasing nuclear GR expression and activity.

CONCLUSIONS

A highly oxidized cysteine redox state promotes a posttranslational modification of the GR that might inhibit its function. Given that cysteine oxidation is prevalent in children with difficult-to-treat asthma, the cysteine redox state might represent a potential therapeutic target for restoration of glucocorticoid responsiveness in this population.

Level of serum neutrophil gelatinase-associated lipocalin in childhood asthma

BACKGROUND

The role of neutrophil gelatinase-associated lipocalin (NGAL) in childhood asthma remains unknown. This study aimed to measure the serum levels of NGAL in children with asthma and to investigate the correlation between NGAL and transforming growth factor beta 1 (TGF-β1), a good indicator of airway remodeling in children with asthma.

METHODS

This prospective, cross-sectional study was conducted on 75 children. Serum NGAL and TGF-β1 concentrations were measured by the ELISA method. Complete blood count, high sensitive C reactive protein (hsCRP), eosinophil cationic protein (ECP), and total serum IgE were investigated in the study population. Atopy in the asthma group was investigated using a skin prick test and specific IgE measurements.

RESULTS

Forty-three asthmatic children and 32 healthy children were enrolled in the study. Total eosinophil numbers, white blood cell count, total serum IgE levels and ECP levels were significantly higher in the asthma group than in the control group (p<0.05). Similarly, serum TGF-β1 levels were significantly higher in children with asthma (p=0.012). The difference in NGAL levels between the groups was insignificant (p=0.268). NGAL levels did not show a significant correlation with total IgE, ECP, eosinophil numbers and TGF-β1 levels (p>0.05).

CONCLUSION

As a conclusion, while elevated TGF-β1 levels in children with asthma might be regarded as an indicator of airway remodeling, we did not find a similar prediction strength for NGAL. Further studies are required to better identify the role of NGAL in childhood asthma and to determine its potential use as a clinical marker.

Fenretinide prevents inflammation and airway hyperresponsiveness in a mouse model of allergic asthma

Arachidonic acid (AA) and docosahexaenoic acid (DHA) play important roles in inflammation and disease progression, where AA is viewed as proinflammatory and DHA as antiinflammatory. We observe in our model of allergic asthma that the AA/DHA ratio is significantly skewed in a proinflammatory direction. Fenretinide, a vitamin A derivative, has been shown to correct fatty acid imbalances in other diseases. Therefore, we explored if fenretinide can have a protective effect in allergic asthma. To accomplish this, we measured the levels of AA and DHA in the lungs of nonallergic, ovalbumin-induced allergic, and fenretinide-treated allergic mice. We also investigated the effect of allergic asthma and fenretinide treatment on markers of oxidative stress, levels of metabolites, IgE production, airway hyperresponsiveness, and histological changes. Our data demonstrate that treatment of allergen-sensitized mice with fenretinide before allergen challenge prevents ovalbumin-induced changes in the AA/DHA ratio. The levels of several metabolites, such as serotonin, and markers of cellular stress, which are increased after ovalbumin challenge, are also controlled by fenretinide treatment. We observed the protective effect of fenretinide against ovalbumin-induced airway hyperresponsiveness and inflammation in the lungs, illustrated by a complete block in the infiltration of inflammatory cells to the airways and dramatically diminished goblet cell proliferation, even though IgE remained high. Our results demonstrate that fenretinide is an effective agent targeting inflammation, oxidation, and lung pathology observed in allergic asthma.

Triptolide inhibits TGF-β1 induced proliferation and migration of rat airway smooth muscle cells by suppressing NF-κB but not ERK1/2

BACKGROUND

Airway remodeling contributes to increased mortality in asthma. We have reported that triptolide can inhibit airway remodeling in a mouse asthma model. In this study, we aimed to investigate the effect of triptolide on airway smooth muscle cells (ASMCs) proliferation, migration and the possible mechanism.

METHODS

Rat airway smooth muscle cells were cultured and made synchronized, then pretreated with different concentrations of triptolide before stimulated by TGF-β1. Cell proliferation was evaluated by cell counting and MTT assay. Flow cytometry was used to study the influence of triptolide on cell cycle. Migration was measured by Transwell analysis. Signal proteins (NF-κB p65 and ERK1/2) were detected by western blotting analysis. LDH releasing test and flow cytometry analysis of apoptosis were also performed to explore the potential cytotoxic or pro-apoptotic effects of triptolide.

RESULTS

Triptolide significantly inhibited TGF-β1 induced ASMC proliferation and migration (p<0.05). The cell cycle was blocked at G1/S-interphase by triptolide dose dependently. Western blotting analysis showed TGF-β1 induced NF-κB p65 phosphorylation was inhibited by triptolide pretreatment, but ERK1/2 was not affected. No cytotoxic or pro-apoptotic effects were detected under the concentration of triptolide we used.

CONCLUSIONS

Triptolide may function as an inhibitor of asthma airway remodeling by suppressing ASMCs proliferation and migration through inactivation of NF-κB pathway. This article is protected by copyright. All rights reserved.

Transforming growth factor β and severe asthma: a perfect storm

Asthma is a chronic inflammatory airway disease involving complex interplay between resident and infiltrative cells, which in turn are regulated by a wide range of host mediators. Identifying useful biomarkers correlating with clinical symptoms and degree of airway obstruction remain important to effective future asthma treatments. Transforming growth factor β (TGF-β) is a major mediator involved in pro-inflammatory responses and fibrotic tissue remodeling within the asthmatic lung. Its role however, as a therapeutic target remains controversial. The aim of this review is to highlight its role in severe asthma including interactions with adaptive T-helper cells, cytokines and differentiation through regulatory T-cells. Associations between TGF-β and eosinophils will be addressed and the effects of genetic polymorphisms of the TGF-β1 gene explored in the context of asthma. We highlight TGF-β1 as a potential future therapeutic target in severe asthma including its importance in identifying emerging clinical phenotypes in asthmatic subjects who may be suitable for individualized therapy through TGF-β modulation.

Asthmatic airway epithelial cells differentially regulate fibroblast expression of extracellular matrix components

BACKGROUND

Airway remodeling might explain lung function decline among asthmatic children. Extracellular matrix (ECM) deposition by human lung fibroblasts (HLFs) is implicated in airway remodeling. Airway epithelial cell (AEC) signaling might regulate HLF ECM expression.

OBJECTIVES

We sought to determine whether AECs from asthmatic children differentially regulate HLF expression of ECM constituents.

METHODS

Primary AECs were obtained from well-characterized atopic asthmatic (n = 10) and healthy (n = 10) children intubated during anesthesia for an elective surgical procedure. AECs were differentiated at an air-liquid interface for 3 weeks and then cocultured with HLFs from a healthy child for 96 hours. Collagen I (COL1A1), collagen III (COL3A1), hyaluronan synthase (HAS) 2, and fibronectin expression by HLFs and prostaglandin E2 synthase (PGE2S) expression by AECs were assessed by using RT-PCR. TGF-β1 and TGF-β2 concentrations in media were measured by using ELISA.

RESULTS

COL1A1 and COL3A1 expression by HLFs cocultured with AECs from asthmatic patients was greater than that by HLFs cocultured with AECs from healthy subjects (2.2-fold, P < .02; 10.8-fold, P < .02). HAS2 expression by HLFs cocultured with AECs from asthmatic patients was 2.5-fold higher than that by HLFs cocultured with AECs from healthy subjects (P < .002). Fibronectin expression by HLFs cocultured with AECs from asthmatic patients was significantly greater than that by HLFs alone. TGF-β2 activity was increased in cocultures of HLFs with AECs from asthmatic patients (P < .05), whereas PGES2 was downregulated in AEC-HLF cocultures (2.2-fold, P < .006).

CONCLUSIONS

HLFs cocultured with AECs from asthmatic patients showed differential expression of the ECM constituents COL1A1 and COL3A1 and HAS2 compared with HLFs cocultured with AECs from healthy subjects. These findings support a role for altered ECM production in asthmatic airway remodeling, possibly regulated by unbalanced AEC signaling.

The role of transforming growth factor-β1 in airway inflammation of childhood asthma

TGF-beta-targeting structural and inflammatory cells has been implicated in the mechanisms leading to the inflammatory and restructuring processes in asthma, suggesting an impact of TGF-beta1 signaling on the development and persistency of this disease. We investigated the potential early involvement of TGF-beta1 activity in the immunological and molecular mechanisms underlying progression of inflammation in childhood asthma. We evaluated the levels of TGF-beta1 in induced sputum supernatants (ISSs) and the expression of small mother cell against decapentaplegic (Smad) 2 and Smad7 proteins in induced sputum cells (ISCs) from children with intermittent asthma (IA), moderate asthma (MA) and control subjects (C). Furthermore, we investigated the regulatory role of TGF-beta1 activity on eosinophil and neutrophil adhesion to epithelial cells using adhesion assay, and on the granulocyte expression of adhesion molecule CD11b/CD18 Macrophage-1 antigen (MAC-1), by flow cytometry. We found that the levels of TGF-beta1 are increased in ISSs of IA and MA in comparison to C, concomitantly to the activation of intracellular signaling TGFbeta/Smads pathway in ISCs. In MA, TGF-beta1 levels correlated with the number of sputum eosinophils and neutrophils. Furthermore, we showed the ability of sputum TGF-beta1 to promote eosinophil and neutrophil adhesion to epithelial cells, and to increase the expression of MAC-1 on the granulocyte surface. This study shows the activation of TGFbeta/Smad signaling pathway in the airways of children with IA and, despite the regular ICS treatment, in children with MA, and provides evidence for the contribution of TGF-beta1 in the regulation of granulocyte activation and trafficking.

A liver-X-receptor ligand, T0901317, attenuates IgE production and airway remodeling in chronic asthma model of mice

The liver-X-receptors have shown anti-inflammatory ability in several animal models of respiratory disease. Our purpose is to investigate the effect of LXR ligand in allergen-induced airway remodeling in mice. Ovalbumin-sensitized mice were chronically challenged with aerosolized ovalbumin for 8 weeks. Some mice were administered a LXR agonist, T0901317 (12.5, 25, 50 mg/kg bodyweight) before challenge. Then mice were evaluated for airway inflammation, airway hyperresponsiveness and airway remodeling. T0901317 failed to attenuate the inflammatory cells and Th2 cytokines in bronchoalveolar lavage fluid. But the application of T0901317 reduced the thickness of airway smooth muscle and the collagen deposition. Meanwhile, T0901317 treatment evidently abolished the high level of OVA-specific IgE, TGF-β1 and MMP-9 in lung. So LXRs may attenuate the progressing of airway remodeling, providing a potential treatment of asthma.