HB-EGF-Promoted Airway Smooth Muscle Cells and Their Progenitor Migration Contribute to Airway Smooth Muscle Remodeling in Asthmatic Mouse

Eosinophils and tissue remodeling: Relevance to airway disease

The ability of human tissue to reorganize and restore its existing structure underlies tissue homeostasis in the healthy airways, but in disease can persist without normal resolution, leading to an altered airway structure. Eosinophils play a cardinal role in airway remodeling both in health and disease, driving epithelial homeostasis and extracellular matrix turnover. Physiological consequences associated with eosinophil-driven remodeling include impaired lung function and reduced bronchodilator reversibility in asthma, and obstructed airflow in chronic rhinosinusitis with nasal polyps. Given the contribution of airway remodeling to the development and persistence of symptoms in airways disease, targeting remodeling is an important therapeutic consideration. Indeed, there is early evidence that eosinophil attenuation may reduce remodeling and disease progression in asthma. This review provides an overview of tissue remodeling in both health and airway disease with a particular focus on eosinophilic asthma and chronic rhinosinusitis with nasal polyps, as well as the role of eosinophils in these processes and the implications for therapeutic interventions. Areas for future research are also noted, to help improve our understanding of the homeostatic and pathological roles of eosinophils in tissue remodeling, which should aid the development of targeted and effective treatments for eosinophilic diseases of the airways.

Epidermal growth factor receptor in asthma: A promising therapeutic target?

Activation of the epidermal growth factor receptor (EGFR) pathway is involved in the pathogenesis of asthma. Although decades of intensive research have focused on the role of EGFR in asthma, the specific mechanisms and pathways of EGFR signaling remain unclear. Various reports have indicated that inhibition of EGFR improves the pathological features in asthma models. However, extending these experimental findings to clinical applications is difficult. Several measures can be adopted to promote clinical application of EGFR inhibitors. This review focuses on the role of EGFR in the pathogenesis of asthma and the development of a potentially novel therapeutic target for asthma.

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.

HB-EGF-induced IL-8 secretion from airway epithelium leads to lung fibroblast proliferation and migration

BACKGROUND

We have reported that heparin-binding epidermal growth factor (HB-EGF) is increased in patients with chronic obstructive pulmonary disease (COPD) and associated with collagen deposition, but the mechanisms remain unclear. In the present study, we aimed to investigated the inflammatory cytokines secreted by bronchial epithelial cells following exposure to HB-EGF that promoted proliferation and migration of human lung fibroblast.

METHODS

HB-EGF-induced inflammatory cytokines were assayed in two airway epithelial cells (primary human bronchial epithelial cells [HBECs] and BEAS-2B cells). Moreover, the culture supernatants derived from HB-EGF-treated HBECs and BEAS-2B cells were added to human primary lung fibroblasts. The effect of culture supernatants on proliferation and migration of fibroblasts was assessed.

RESULTS

IL-8 expression was significantly increased in bronchial epithelial cells treated with HB-EGF, which was at least partially dependent on NF-kB pathways activation. HB-EGF-induced IL-8 was found to further promote lung fibroblasts proliferation and migration, and the effects were attenuated after neutralizing IL-8.

CONCLUSIONS

These findings suggest that HB-EGF may be involved in the pathology of airway fibrosis by induction of IL-8 from airway epithelium, subsequently causing lung fibroblasts proliferation and migration. Thus, inhibition of HBEGF and/or IL-8 production could prevent the development of airway fibrosis by modulating fibroblast activation.

LncRNAs and their regulatory networks in breast muscle tissue of Chinese Gushi chickens during late postnatal development

BACKGROUND

Chicken skeletal muscle is an important economic product. The late stages of chicken development constitute the main period that affects meat production. LncRNAs play important roles in controlling the epigenetic process of growth and development. However, studies on the role of lncRNAs in the late stages of chicken breast muscle development are still lacking. In this study, to investigate the expression characteristics of lncRNAs during chicken muscle development, 12 cDNA libraries were constructed from Gushi chicken breast muscle samples from 6-, 14-, 22-, and 30-week-old chickens.

RESULTS

A total of 1252 new lncRNAs and 1376 annotated lncRNAs were identified. Furthermore, 53, 61, 50, 153, 117, and 78 DE-lncRNAs were found in the W14 vs. W6, W22 vs. W14, W22 vs. W6, W30 vs. W6, W30 vs. W14, and W30 vs. W22 comparison groups, respectively. After GO enrichment analysis of the DE-lncRNAs, several muscle development-related GO terms were found in the W22 vs. W14 comparison group. Moreover, it was found that the MAPK signaling pathway was one of the most frequently enriched pathways in the different comparison groups. In addition, 12 common target DE-miRNAs of DE-lncRNAs were found in different comparison groups, some of which were muscle-specific miRNAs, such as gga-miR-206, gga-miR-1a-3p, and miR-133a-3p. Interestingly, the precursors of four newly identified miRNAs were found to be homologous to lncRNAs. Additionally, we found some ceRNA networks associated with muscle development-related GO terms. For example, the ceRNA networks contained the DYNLL2 gene with 12 lncRNAs that targeted 2 miRNAs. We also constructed PPI networks, such as IGF-I-EGF and FZD6-WNT11.

CONCLUSIONS

This study revealed, for the first time, the dynamic changes in lncRNA expression in Gushi chicken breast muscle at different periods and revealed that the MAPK signaling pathway plays a vital role in muscle development. Furthermore, MEF2C and its target lncRNA may be involved in muscle regulation through the MAPK signaling pathway. This research provided valuable resources for elucidating posttranscriptional regulatory mechanisms to promote the development of chicken breast muscles after hatching.

Tespa1 plays a role in the modulation of airway hyperreactivity through the IL-4/STAT6 pathway

BACKGROUND

Thymocyte-expressed, positive selection-associated 1 (Tespa1) is a critical signaling molecule in thymocyte development. This study aimed to investigate the regulatory effect of Tespa1 on mast cells in the pathogenesis of asthma and its relationship with the interleukin (IL)-4/signal transducers and activators of transcription 6 (STAT6) signaling pathway.

METHODS

Tespa1 mRNA expression analysis and IgE levels were carried out using the induced sputum of 33 adults with stable asthma and 36 healthy controls. Tespa1-knockout mice (Tespa1-/-, KO) and C57BL/6 background (wild-type, WT) mice were sensitized and treated with ovalbumin (OVA) to establish an asthma model. Pathological changes, number and activity of mast cells, and changes in activation of the IL-4/STAT6 pathway in lung tissue were detected. The changes of tryptase expression and STAT6 activation after mast cell gene knockout were analyzed in vitro. The changes of enzyme expression and STAT6 activation after mast cell gene knockout were analyzed in vitro. The association between the Tespa1 and p-STAT6 was analyzed by co-immunoprecipitation method.

RESULTS

Compared with the healthy controls, Tespa1 expression was decreased, and IgE levels were elevated in the sputum of asthmatic patients. Animal experiments showed that Tespa1-/- mice exhibited more severe inflammation, higher quantity of goblet cells and mast cells in the bronchium, and greater expression of mast cell tryptase, which is induced by ovalbumin, than WT mice. And IL-4, IL-13, phospho-Janus kinase 1, and p-STAT6 expressions presented a higher increase in the Tespa1-/- mouse model than in the WT mouse model. Further in vitro studies confirmed that IL-4 could more significantly promote tryptase and p-STAT6 activities in Tespa1-/- mast cells than their WT counterparts. Correlation analysis results showed a negative correlation between Tespa1 and p-STAT6. Co-immunoprecipitation results demonstrated an association between Tespa1 and p-STAT6.

CONCLUSIONS

Altogether, our results indicate that Tespa1 can negatively regulate mast cell activity, and this event is related to the mast cell IL-4/STAT6 signaling pathway and could be therapeutically exploited to treat asthma attacks.

Modified method for effective primary vascular smooth muscle progenitor cell culture from peripheral blood

In previous studies, vascular smooth muscle progenitor cells (vSMPCs) isolated from peripheral blood mononuclear cells (PBMCs) were cultured using medium containing platelet-derived growth factor-BB (PDGF-BB) for 4 weeks. However, this method requires long culture periods of up to 4 weeks and yields low cell counts. Therefore, we proposed the modified method to improve the cell yield and purity and to reduce the cell culture period. PBMCs were isolated from human peripheral blood and cultured by the conventional method using medium containing PDGF-BB alone or the modified method using medium containing PDGF-BB, basic fibroblast growth factor (bFGF), and insulin-transferrin-selenium ITS for 4 weeks. The purity of vSMPCs was analyzed for the expression of a- smooth muscle actin (SMA) by flow cytometry and significantly higher in the modified method than conventional methods at the 1st and 2nd weeks. Also, mRNA expression of a-SMA by real-time PCR was significantly higher in the modified method than conventional method at the 2 weeks. The yield of vSMPCs by trypan blue exclusion assay was significantly higher in the modified method than conventional method at the 1st, 2nd and 3rd weeks. The primary culture using the modified method with PDGF-BB, bFGF, and ITS not only improved cell purity and yield, but also shortened the culture period, compared to the conventional culture method for vSMPCs. The modified method will be a time-saving and useful tool in various studies related to vascular pathology.

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

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

TSLP promotes asthmatic airway remodeling via p38-STAT3 signaling pathway in human lung fibroblast

PURPOSE

Thymic stromal lymphopoietin (TSLP) acts as a critical cytokine involved in asthmatic airway remodeling. Our study aimed to characterize the crosstalk between airway epithelial cells and fibroblasts regulated by TSLP through the signaling pathways of Mitogen-activated protein kinase (MAPK) and signal transducer and activator of transcription 3 (STAT3).

MATERIALS AND METHODS

Human biopsy specimens and lung tissues from mice were stained with hematoxylin and eosin (H&E) and immunohistochemistry. Human lung fibroblasts were stimulated with human recombinant TSLP. The protein expression of phosphorylation of STAT3 (p-STAT3) and phosphorylation of MAPK as well as the expression of collagen I and alpha-smooth muscle actin (α-SMA) were detected by Western blotting and immunofluorescence. Co-culture was performed to detect the influence of TSLP secreted by airway epithelial cells on fibroblasts. An ovalbumin (OVA)-induced asthmatic murine model was established with or without intraperitoneal injection of SB203580 (inhibitor of p-38). Protein expression in lung tissue was detected by immunohistochemistry and western blotting.

RESULT

TSLP could activate MAPK in HLF-1. SB203580 could inhibit the activation of p38, attenuate phosphorylation of STAT3, and decrease the expression of collagen I and α-SMA consequently in human fibroblasts. Co-culture demonstrated that TSLP secreted by epithelial cells could promote the expression of collagen I and α-SMA and aggravates airway remodeling in fibroblasts. In vivo, expression of TSLP, collagen I, α-SMA, p-p38 and p-STAT3 was upregulated in airway tissue of OVA-challenged mice and downregulated in mice which were treated by SB203580. The tissue staining showed that airway structure change was attenuated by SB203580 compared with OVA challenged mice as well.

CONCLUSIONS

TSLP might promote asthmatic airway remodeling via p38 MAPK-STAT3 axis activation and the crosstalk between airway epithelial cells and fibroblasts could aggravate remodeling. Blockade of p38 could alleviate airway remodeling which might provide a new therapeutic target for asthma.

Ibrutinib Exacerbates Bleomycin-Induced Pulmonary Fibrosis via Promoting Inflammation

Idiopathic pulmonary fibrosis (IPF) is a progressive and irreversible lung disease with high mortality rate. The etiology is unknown and treatment choices are limited. Thus, there is great interest to investigate novel agents for IPF therapy. Ibrutinib, BTK, and ITK irreversible inhibitor is a FDA-approved small molecule for the clinical therapy of B cell lymphoma. Its role in pulmonary fibrosis remains unknown. In this study, we investigated the anti-fibrotic activity of ibrutinib. Strikingly, ibrutinib did not inhibit but exacerbated bleomycin-induced pulmonary fibrosis by increased epithelial cell apoptosis, and inflammation in the lung. The upregulated TGF-β and EMT transformation also contributes to enhanced myofibroblast differentiation and ECM deposition. Our findings reveal the detrimental effects of ibrutinib against bleomycin-mediated fibrosis and added to the understanding of IPF pathogenesis.

Heparin-binding epidermal growth factor contributes to COPD disease severity by modulating airway fibrosis and pulmonary epithelial-mesenchymal transition

Although airway fibrosis and epithelial-mesenchymal transition (EMT) contribute to airway remodeling in chronic obstructive pulmonary disease (COPD), the mechanisms underlying their development have not been fully elucidated. In the present study, we aimed to assess heparin-binding epidermal growth factor (HB-EGF) expression in the airways of patients with COPD and to elucidate the possible role of HB-EGF in the pathology of COPD. Sputum and lung tissue HB-EGF expression was evaluated in control subjects and patients with COPD. The relationships between HB-EGF expression, disease severity, collagen deposition (fibrosis), and EMT were investigated. In vitro, human bronchial epithelial (HBE) cells and lung fibroblast cells exposed to the recombinant HB-EGF, collagen deposition and EMT were assessed. We found that sputum HB-EGF expression was significantly increased in patients with COPD compared with non-smokers and smokers without COPD. There was a significant positive correlation between sputum HB-EGF and COPD assessment test (CAT) score. HB-EGF expression was significantly increased in the lung tissue samples of patients with COPD and associated with collagen deposition and N- and E-cadherin, and vimentin expression. In vitro, HB-EGF promoted collagen production in lung fibroblasts. Moreover, HB-EGF induced the EMT process through induction of N-and E-cadherin, and vimentin expression in HBE cells. Collectively, HB-EGF induces airway remodeling by modulating airway fibrosis and pulmonary EMT, and contributes to the COPD severity. The current data may provide insight into the underlying pathogenesis of COPD, in which HB-EGF has an important pathogenic role.

Interleukin-37 alleviates airway inflammation and remodeling in asthma via inhibiting the activation of NF-κB and STAT3 signalings

Asthma is a common respiratory inflammatory disorder disease of childhood, and airway smooth muscle cells (ASMCs) play an important role in this disease. Recently, studies have found that interleukin (IL)-37 inhibits allergic airway inflammation of asthmatic mouse models. The aim of this study was to investigate the exact mechanism of IL-37 in asthma. In this study, we found recombinant human IL-37 protein significantly reduced ovalbumin (OVA)-induced airway hyperresponsiveness, inflammatory cell infiltration, the epithelial-mesenchymal-transition (EMT) process, and levels of IL-4, IL-6 and IL-13, but increased interferon (IFN)-γ expression. Moreover, IL-37 treatment remarkably inhibited transforming growth factor (TGF)-β1-induced cell proliferation, migration, EMT, and inflammatory response in ASMCs. IL-37 notably upregulated IκB expression and downregulated levels of NF-κB p65, phospho-NF-κB p65, STAT3 and phospho-STAT3 both in OVA-induced mice and in TGF-β1-stimulated ASMCs. The effects of IL-37 on TGF-β1-induced ASMCs were abrogated by STAT3 upregulation. Additionally, PDTC, a NF-κB inhibitor, showed the similar effects as IL-37 in ASMCs. In conclusion, IL-37 may alleviate airway inflammation and remodeling in asthma through suppressing the activation of NF-κB and STAT3.

Store-operated Ca2+ channels in airway epithelial cell function and implications for asthma

The epithelial cells of the lung are at the interface of a host and its environment and are therefore directly exposed to the inhaled air-borne particles. Rather than serving as a simple physical barrier, airway epithelia detect allergens and other irritants and then help organize the subsequent immune response through release of a plethora of secreted signals. Many of these signals are generated in response to opening of store-operated Ca²⁺ channels in the plasma membrane. In this review, we describe the properties of airway store-operated channels and their role in regulating airway epithelial cell function.

This article is part of the themed issue ‘Evolution brings Ca²⁺ and ATP together to control life and death’.

Fibulin-5 promotes airway smooth muscle cell proliferation and migration via modulating Hippo-YAP/TAZ pathway

Asthma is a common chronic disease mainly occurs from childhood. Increased airway smooth muscle mass is involved in the pathogenesis of asthma. Fibulin-5 was upregulated in the lung tissues of patients with COPD and idiopathic pulmonary fibrosis. This study aimed to investigate Fibulin-5 expression in asthmatic patients and the effect and mechanism of Fibulin-5 on the proliferation and migration of airway smooth muscle cells (ASMCs). The expression of Fibulin-5, YAP, and TAZ in the induced sputum of 38 asthmatic children (19 mild and 19 moderate asthmatics) and 19 healthy controls was determined. The effects and mechanisms of Fibulin-5 on the proliferation and migration of ASMCs were analyzed through upregulating Fibulin-5. We found compared with healthy controls, the expression of Fibulin-5, YAP, and TAZ was increased in the induced sputum of asthmatic children and much higher in moderate asthmatics. Fibulin-5 overexpression promoted the proliferation and migration of ASMCs, upregulated the expression of YAP and TAZ, and reduced the levels of p-YAP and p-TAZ. YAP inhibitor (Peptide 17) abrogated the proliferation and migration of ASMCs induced by Fibulin-5 overexpression in a dose-dependent manner. Additionally, Fibulin-5 overexpression enhanced its binding capacity of β1 integrin, and β1 integrin blocking antibody partly reversed the effect of Fibulin-5 overexpression on the levels of YAP and TAZ. In conclusion, Fibulin-5 expression is correlated with the pathogenesis of childhood asthma. It may function at least partly through binding to β1 integrin and modulating Hippo-YAP/TAZ pathway to promote the proliferation and migration of ASMCs.

Regulation of human airway smooth muscle cell migration and relevance to asthma

Airway remodelling is an important feature of asthma pathogenesis. A key structural change inherent in airway remodelling is increased airway smooth muscle mass. There is emerging evidence to suggest that the migration of airway smooth muscle cells may contribute to cellular hyperplasia, and thus increased airway smooth muscle mass. The precise source of these cells remains unknown. Increased airway smooth muscle mass may be collectively due to airway infiltration of myofibroblasts, neighbouring airway smooth muscle cells in the bundle, or circulating hemopoietic progenitor cells. However, the relative contribution of each cell type is not well understood. In addition, although many studies have identified pro and anti-migratory agents of airway smooth muscle cells, whether these agents can impact airway remodelling in the context of human asthma, remains to be elucidated. As such, further research is required to determine the exact mechanism behind airway smooth muscle cell migration within the airways, how much this contributes to airway smooth muscle mass in asthma, and whether attenuating this migration may provide a therapeutic avenue for asthma. In this review article, we will discuss the current evidence with respect to the regulation of airway smooth muscle cell migration in asthma.

Anti-asthmatic effect of pitavastatin through aerosol inhalation is associated with CD4+ CD25+ Foxp3+ T cells in an asthma mouse model

Statins are competitive inhibitors of 3-hydroxy-3-methylglutaryl-CoA (HMG-A) reductase, and studies have shown that statins also have anti-inflammatory and immunomodulatory properties. The purpose of this study was to investigate the anti-asthmatic effects of pitavastatin, a type of statin, in an asthma mouse model. Mice were sensitized and challenged with ovalbumin (OVA) to establish the asthma model. These mice were then treated with inhaled pitavastatin (5 mg/kg) or dexamethasone (2 mg/kg), the latter of which served as a positive control. The results of the study showed that pitavastatin reduced allergen-induced increases in airway resistance and alleviated bronchial tube thickness and goblet cell hyperplasia in lung tissues. In addition, the results showed that pitavastatin inhibited OVA-induced increases in eosinophil counts and total inflammatory cell counts in bronchoalveolar lavage fluid (BALF) and increased the percentage of CD4+ CD25+ Foxp3+ Treg in the BALF of asthmatic mice. IL-4 and IL-17 levels were decreased, whereas IFN-γ levels were significantly increased in the BALF of pitavastatin-treated mice compared with the BALF of OVA-challenged mice. These results suggest that pitavastatin has potential as a therapy for allergic airway disease and that its effects are associated with its ability to regulate CD4+ CD25+ Foxp3+ T cell counts.

Reduction of Asthmatic Parameters by Sea Hare Hydrolysates in a Mouse Model of Allergic Asthma

Sea hare has a variety of biological activities. However, little is known regarding the anti-asthmatic effects of sea hare. This study was performed to identify the effect of sea hare hydrolysates (SHH) on an ovalbumin (OVA)-induced allergic asthma model. The experimental asthma model was sensitized and challenged with OVA. We found that a high-dose of SHH (HSHH) significantly inhibited OVA-induced airway inflammation and mucus production around the airway in lung sections, while low- and medium-dose SHH showed an insignificant effect. In addition, HSHH highly reduced OVA-induced production of interleukin-4, -5, -13, leukotriene D4, E4, and histamine in bronchoalveolar lavage fluid. HSHH decreased the histamine-induced increase in the intracellular Ca²⁺ level and contractions in asthmatic smooth muscle cells. Furthermore, HSHH did not affect the weights of the spleen nor thymus, whereas dexamethasone (DEX), a steroidal anti-inflammatory drug, reduced them. Taken together, these results showed that HSHH reduced asthmatic parameters in a mouse model of allergic asthma, and suggest that SHH could be used as a potential therapeutic agent for asthma.

The Biology of Eosinophils and Their Role in Asthma

This review will describe the structure and function of the eosinophil. The roles of several relevant cell surface molecules and receptors will be discussed. We will also explore the systemic and local processes triggering eosinophil differentiation, maturation, and migration to the lungs in asthma, as well as the cytokine-mediated pathways that result in eosinophil activation and degranulation, i.e., the release of multiple pro-inflammatory substances from eosinophil-specific granules, including cationic proteins, cytokines, chemokines growth factors, and enzymes. We will discuss the current understanding of the roles that eosinophils play in key asthma processes such as airway hyperresponsiveness, mucus hypersecretion, and airway remodeling, in addition to the evidence relating to eosinophil–pathogen interactions within the lungs.