Airway remodeling and airway smooth muscle in asthma

Transcriptomic evaluation of skin tape-strips in children with allergic asthma uncovers epidermal barrier dysfunction and asthma-associated biomarkers abnormalities

INTRODUCTION

Tape-strips, a minimally invasive method validated for the evaluation of several skin diseases, may help identify asthma-specific biomarkers in the skin of children with allergic asthma.

METHODS

Skin tape-strips were obtained and analyzed with RNA-Seq from children with moderate allergic asthma (MAA) (n = 11, mean age 7.00; SD = 1.67), severe allergic asthma (SAA) (n = 9, mean age 9.11; SD = 2.37), and healthy controls (HCs) (n = 12, mean age 7.36; SD = 2.03). Differentially expressed genes (DEGs) were identified by fold change ≥2 with a false discovery rate <0.05. Transcriptomic biomarkers were analyzed for their accuracy in distinguishing asthma from HCs, their relationships with asthma-related outcomes (exacerbation rate, lung function-FEV1, IOS-R5-20, and lung inflammation-FeNO), and their links to skin (barrier and immune response) and lung (remodeling, metabolism, aging) pathogenetic pathways.

RESULTS

RNA-Seq captured 1113 in MAA and 2117 DEGs in SAA. Epidermal transcriptomic biomarkers for terminal differentiation (FLG/filaggrin), cell adhesion (CDH19, JAM2), lipid biosynthesis/metabolism (ACOT2, LOXL2) were significantly downregulated. Gene set variation analysis revealed enrichment of Th1/IFNγ pathways (p < .01). MAA and SAA shared downregulation of G-protein-coupled receptor (OR4A16, TAS1R3), upregulation of TGF-β/ErbB signaling-related (ACVR1B, EGFR, ID1/2), and upregulation of mitochondrial-related (HIGD2A, VDAC3, NDUFB9) genes. Skin transcriptomic biomarkers correlated with the annualized exacerbation rate and with lung function parameters. A two-gene classifier (TSSC4-FAM212B) was able to differentiate asthma from HCs with 100% accuracy.

CONCLUSION

Tape-strips detected epithelial barrier and asthma-associated signatures in normal-appearing skin from children with allergic asthma and may serve as an alternative to invasive approaches for evaluating asthma endotypes.

Impact of obesity on airway remodeling in asthma: pathophysiological insights and clinical implications

The prevalence of obesity among asthma patients has surged in recent years, posing a significant risk factor for uncontrolled asthma. Beyond its impact on asthma severity and patients' quality of life, obesity is associated with reduced lung function, increased asthma exacerbations, hospitalizations, heightened airway hyperresponsiveness, and elevated asthma-related mortality. Obesity may lead to metabolic dysfunction and immune dysregulation, fostering chronic inflammation characterized by increased pro-inflammatory mediators and adipocytokines, elevated reactive oxygen species, and reduced antioxidant activity. This chronic inflammation holds the potential to induce airway remodeling in individuals with asthma and obesity. Airway remodeling encompasses structural and pathological changes, involving alterations in the airway's epithelial and subepithelial layers, hyperplasia and hypertrophy of airway smooth muscle, and changes in airway vascularity. In individuals with asthma and obesity, airway remodeling may underlie heightened airway hyperresponsiveness and increased asthma severity, ultimately contributing to the development of persistent airflow limitation, declining lung function, and a potential increase in asthma-related mortality. Despite efforts to address the impact of obesity on asthma outcomes, the intricate mechanisms linking obesity to asthma pathophysiology, particularly concerning airway remodeling, remain incompletely understood. This comprehensive review discusses current research investigating the influence of obesity on airway remodeling, to enhance our understanding of obesity's role in the context of asthma airway remodeling.

Estrogen receptors differentially modifies lamellipodial and focal adhesion dynamics in airway smooth muscle cell migration

Sex-steroid signaling, especially estrogen, has a paradoxical impact on regulating airway remodeling. In our previous studies, we demonstrated differential effects of 17β-estradiol (E2) towards estrogen receptors (ERs: α and β) in regulating airway smooth muscle (ASM) cell proliferation and extracellular matrix (ECM) production. However, the role of ERs and their signaling on ASM migration is still unexplored. In this study, we examined how ERα versus ERβ affects the mitogen (Platelet-derived growth factor, PDGF)-induced human ASM cell migration as well as the underlying mechanisms involved. We used Lionheart-FX automated microscopy and transwell assays to measure cell migration and found that activating specific ERs had differential effects on PDGF-induced ASM cell migration. Pharmacological activation of ERβ or shRNA mediated knockdown of ERα and specific activation of ERβ blunted PDGF-induced cell migration. Furthermore, specific ERβ activation showed inhibition of actin polymerization by reducing the F/G-actin ratio. Using Zeiss confocal microscopy coupled with three-dimensional algorithmic ZEN-image analysis showed an ERβ-mediated reduction in PDGF-induced expressions of neural Wiskott-Aldrich syndrome protein (N-WASP) and actin-related proteins-2/3 (Arp2/3) complex, thereby inhibiting actin-branching and lamellipodia. In addition, ERβ activation also reduces the clustering of actin-binding proteins (vinculin and paxillin) at the leading edge of ASM cells. However, cells treated with E2 or ERα agonists do not show significant changes in actin/lamellipodial dynamics. Overall, these findings unveil the significance of ERβ activation in regulating lamellipodial and focal adhesion dynamics to regulate ASM cell migration and could be a novel target to blunt airway remodeling.

Human Airway Basal Cells Undergo Reversible Squamous Differentiation and Reshape Innate Immunity

Histological and lineage immunofluorescence examination revealed that healthy conducting airways of humans and animals harbor sporadic poorly differentiated epithelial patches mostly in the dorsal noncartilage regions that remarkably manifest squamous differentiation. In vitro analysis demonstrated that this squamous phenotype is not due to intrinsic functional change in underlying airway basal cells. Rather, it is a reversible physiological response to persistent Wnt signaling stimulation during de novo differentiation. Squamous epithelial cells have elevated gene signatures of glucose uptake and cellular glycolysis. Inhibition of glycolysis or a decrease in glucose availability suppresses Wnt-induced squamous epithelial differentiation. Compared with pseudostratified airway epithelial cells, a cascade of mucosal protective functions is impaired in squamous epithelial cells, featuring increased epithelial permeability, spontaneous epithelial unjamming, and enhanced inflammatory responses. Our study raises the possibility that the squamous differentiation naturally occurring in healthy airways identified herein may represent "vulnerable spots" within the airway mucosa that are sensitive to damage and inflammation when confronted by infection or injury. Squamous metaplasia and hyperplasia are hallmarks of many airway diseases, thereby expanding these areas of vulnerability with potential pathological consequences. Thus, investigation of physiological and reversible squamous differentiation from healthy airway basal cells may provide critical knowledge to understand pathogenic squamous remodeling, which is often nonreversible, progressive, and hyperinflammatory.

Baicalin Inhibits Airway Smooth Muscle Cells Proliferation through the RAS Signaling Pathway in Murine Asthmatic Airway Remodeling Model

Background

Studies that looked at asthma airway remodeling pathogenesis and prevention have led to the discovery of the rat sarcoma viral oncogene (RAS) signaling pathway as a key mechanism that controls airway smooth muscle cell (ASMC) proliferation. Baicalin has great anti-inflammatory, proliferation-inhibited, and respiratory disease-relieving properties. However, the inhibitory effects and mechanisms of baicalin on ASMC-mediated airway remodeling in mice are still poorly understood.

Methods

After establishing the asthmatic mice model by ovalbumin (OVA) and interfering with baicalin, airway remodeling characteristics such as airway resistance, mRNA, and protein expression levels of remodeling-related cytokines were measured by histopathological assessment, quantitative real-time polymerase chain reaction (qPCR), enzyme-linked immunosorbent assay (ELISA), and western blot. Further efforts on detailed mechanisms were used antibody arrays to compare the expression and activation of proteins involved in the RAS signaling pathway. In addition, validation experiments were performed in ASMC proliferation model and low-expression cells of the target gene by using shRNA.

Results

In OVA-induced asthmatic mice model, baicalin significantly reduced the infiltration of inflammatory cells in lung tissue, attenuated airway resistance, and decreased mRNA and protein expression levels of remodeling-related cytokines such as interleukin-13 (IL-13), vascular endothelial growth factor (VEGF), transforming growth factor-beta 1 (TGF-β1), matrix metallopeptidase 9 (MMP9), and tissue inhibitor of metalloproteinase 1 (TIMP1). The results of antibody arrays involved in RAS signaling pathway revealed that OVA and baicalin administration altered the activation of protein kinase C alpha type (PKC-α), A-rapidly accelerated fibrosarcoma (A-RAF), mitogen-activated protein kinase 2 (MEK2), extracellular regulated MAP kinase (ERK), MAPK interacting serine/threonine kinase 1 (MNK1), and ETS transcription factor 1 (ELK1). The above results were further verified in the ASMC proliferation model. A-RAF silencing (shA-RAF) could promote ASMC proliferation and downregulate p-MEK2, p-ERK, p-MNK1, and p-ELK1 expression.

Conclusion

The effects of baicalin against airway remodeling and ASMC proliferation might partially be achieved by suppressing the RAS signaling pathway. Baicalin may be a new therapeutic option for managing airway remodeling in asthma patients.

Chryseriol attenuates the progression of OVA-induced asthma in mice through NF-κB/HIF-1α and MAPK/STAT1 pathways

BACKGROUND

Asthma is a hackneyed chronic inflammatory disease of the airway. Chryseriol (CSR) is a kind of flavonoid, and has the effect of bronchiectasis, indicating its potential application for treating respiratory diseases. However, the functions of CSR in asthma have not been reported till now.

MATERIALS AND METHODS

The histopathologic changes of the lung tissues were assessed by hematoxylin and eosin staining. The cell apoptosis was identified through terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling assay. Total numbers of eosinophils, neutrophils, and macrophages were assessed under microscope. The levels of interleukin (IL)-1β, IL-4, IL-5, and IL-13 were detected by enzyme-linked-immunosorbent serologic assay. The airway hyper-responsiveness (AHR) was evaluated by the whole body plethysmography. The levels of methane dicarboxylic aldehyde, superoxide dismutase, glutathione S-transferase, and glutathione in lung homogenates were confirmed by using corresponding commercial kits. The protein expressions were examined by Western blot analysis.

RESULTS

The ovalbumin (OVA) was utilized to establish asthma mouse model. At first, it was revealed that CSR treatment reduced lung injury in OVA-stimulated mice. Moreover, cell apoptosis was enhanced after OVA stimulation but was attenuated by CSR treatment. In addition, CSR treatment decreased the infiltration of inflammatory cells and the production of inflammatory factors in OVA-treated mice. Further investigations demonstrated that CSR treatment relieved AHR in OVA-stimulated mice. The oxidative stress was strengthened in OVA-treated mice, but these effects were relieved by CSR treatment. Lastly, it was discovered that CSR treatment retarded nuclear factor kappa B (NF-κB)/hypoxia-inducible factor 1 alpha (HIF-1α) and p38 mitogen-activated protein kinase (MAPK)/signal transducer and activator of transcription 1 (STAT1) pathways in OVA-triggered asthma mice.

CONCLUSION

Our findings proved that CSR attenuated the progression of OVA-induced asthma in mice through inhibiting NF-κB/HIF-1α and MAPK/STAT1 pathways. This work might highlight the functions of CSR in the treatment of asthma.

NR4A1 modulates intestinal smooth muscle cell phenotype and dampens inflammation-associated intestinal remodeling

Stricture formation is a common complication of Crohn's disease (CD), driven by enhanced deposition of extracellular matrix (ECM) and expansion of the intestinal smooth muscle layers. Nuclear receptor subfamily 4 group A member 1 (NR4A1) is an orphan nuclear receptor that exhibits anti-proliferative effects in smooth muscle cells (SMCs). We hypothesized that NR4A1 regulates intestinal SMC proliferation and muscle thickening in the context of inflammation. Intestinal SMCs isolated from Nr4a1^+/+ and Nr4a1^-/- littermates were subjected to shotgun proteomic analysis, proliferation, and bioenergetic assays. Proliferation was assessed in the presence and absence of NR4A1 agonists, cytosporone-B (Csn-B) and 6-mercaptopurine (6-MP). In vivo, we compared colonic smooth muscle thickening in Nr4a1^+/+ and Nr4a1^-/- mice using the chronic dextran sulfate sodium (DSS) model of colitis. Second, SAMP1/YitFc mice (a model of spontaneous ileitis) were treated with Csn-B and small intestinal smooth muscle thickening was assessed. SMCs isolated from Nr4a1^-/- mice exhibited increased abundance of proteins related to cell proliferation, metabolism, and ECM production, whereas Nr4a1^+/+ SMCs highly expressed proteins related to the regulation of the actin cytoskeleton and contractile processes. SMCs isolated from Nr4a1^-/- mice exhibited increased proliferation and alterations in cellular metabolism, whereas activation of NR4A1 attenuated proliferation. In vivo, Nr4a1^-/- mice exhibited increased colonic smooth muscle thickness following repeated cycles of DSS. Activating NR4A1 with Csn-B, in the context of established inflammation, reduced ileal smooth muscle thickening in SAMP1/YitFc mice. Targeting NR4A1 may provide a novel approach to regulate intestinal SMC phenotype, limiting excessive proliferation that contributes to stricture development in CD.

Insights into potential mechanisms of asthma patients with COVID-19: A study based on the gene expression profiling of bronchoalveolar lavage fluid

Background

The 2019 novel coronavirus disease (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is currently a major challenge threatening the global healthcare system. Respiratory virus infection is the most common cause of asthma attacks, and thus COVID-19 may contribute to an increase in asthma exacerbations. However, the mechanisms of COVID-19/asthma comorbidity remain unclear.

Methods

The “Limma” package or “DESeq2” package was used to screen differentially expressed genes (DEGs). Alveolar lavage fluid datasets of COVID-19 and asthma were obtained from the GEO and GSV database. A series of analyses of common host factors for COVID-19 and asthma were conducted, including PPI network construction, module analysis, enrichment analysis, inference of the upstream pathway activity of host factors, tissue-specific analysis and drug candidate prediction. Finally, the key host factors were verified in the GSE152418 and GSE164805 datasets.

Results

192 overlapping host factors were obtained by analyzing the intersection of asthma and COVID-19. FN1, UBA52, EEF1A1, ITGB1, XPO1, NPM1, EGR1, EIF4E, SRSF1, CCR5, PXN, IRF8 and DDX5 as host factors were tightly connected in the PPI network. Module analysis identified five modules with different biological functions and pathways. According to the degree values ranking in the PPI network, EEF1A1, EGR1, UBA52, DDX5 and IRF8 were considered as the key cohost factors for COVID-19 and asthma. The H₂O₂, VEGF, IL-1 and Wnt signaling pathways had the strongest activities in the upstream pathways. Tissue-specific enrichment analysis revealed the different expression levels of the five critical host factors. LY294002, wortmannin, PD98059 and heparin might have great potential to evolve into therapeutic drugs for COVID-19 and asthma comorbidity. Finally, the validation dataset confirmed that the expression of five key host factors were statistically significant among COVID-19 groups with different severity and healthy control subjects.

Conclusions

This study constructed a network of common host factors between asthma and COVID-19 and predicted several drugs with therapeutic potential. Therefore, this study is likely to provide a reference for the management and treatment for COVID-19/asthma comorbidity.

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

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

Qufeng Xuanbi Formula Ameliorates Airway Remodeling in Asthmatic Mice by Suppressing Airway Smooth Muscle Cell Proliferation through MEK/ERK Signaling Pathway

Asthma is a common chronic respiratory disease. The Qufeng Xuanbi formula (QFXBF), a Chinese herbal decoction, has shown efficacy in the management of asthma. The purpose of this study was to investigate the potential therapeutic effects of QFXBF in the treatment of asthma both in vitro and in vivo. Platelet-derived growth factor (PDGF)-induced airway smooth muscle cell (ASMC) proliferation and MTT assays were used to explore the effects of QFXBF on the proliferation of ASMCs. Moreover, 40 female BALB/c mice were randomly divided into five groups: control group, ovalbumin (OVA) group, high QFXBF group, low QFXBF group, and dexamethasone (DEX) group (n = 8 per group). A mouse allergic asthma model was established using the intranasally administered OVA sensitization method. Morphological changes in the lung tissue were examined by hematoxylin and eosin (H&E) staining and Masson's trichrome staining. Finally, the protein expression of alpha-smooth muscle actin (α-SMA), proliferating cell nuclear antigen (PCNA), phospho-mitogen-activated protein kinase (p-MEK1/2), mitogen-activated protein kinase (MEK1/2), phospho-extracellular signal-regulated kinases (p-ERK1/2), and extracellular signal-regulated kinases (ERK1/2) in ASMCs and lung tissue were determined by western blotting and immunofluorescent staining assays. PDGF significantly increased the viability of ASMCs. Compared with mice in the control group, the airway walls and airway smooth muscle of mice in the OVA group were thickened, and the number of inflammatory cells around the bronchus significantly increased. Moreover, the administration of QFXBF markedly inhibited the proliferation of ASMCs and alleviated the pathological changes induced by OVA. Furthermore, the protein expressions of p-ERK1/2, p-MEK1/2, PCNA, and α-SMA were significantly increased in OVA-treated mice and PDGF-treated ASMCs. Finally, treatment with QFXBF also significantly decreased the protein expression of p-ERK1/2, p-MEK1/2, α-SMA, and PCNA. QFXBF inhibited the proliferation of ASMCs by suppressing MEK/ERK signaling in PDGF-induced ASMCs and OVA-induced mice.

MiR-18a Inhibits PI3K/AKT Signaling Pathway to Regulate PDGF BB-Induced Airway Smooth Muscle Cell Proliferation and Phenotypic Transformation

The increased proliferation and migration of airway smooth muscle cells (ASMCs) is a key process in the formation of airway remodeling in asthma. In this study, we focused on the expression of mircoRNA-18a (miR-18a) in airway remodeling in bronchial asthma and its related mechanisms. ASMCs are induced by platelet-derived growth factor BB (PDGF-BB) for in vitro airway remodeling. The expression of miR-18a in sputum of asthmatic patients and healthy volunteers was detected by qRT-PCR. The expression of miR-18a was over-expressed or interfered with in PDGF-BB-treated ASMCs. Cell proliferation, apoptosis and migration were detected by MTT, flow cytometry and Transwell, respectively; the expression of contractile phenotype marker proteins (SM-22α, α-SM-actin, calponin) and key molecules of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway (PI3K, p-PI3K, AKT and p-AKT) in ASMCs were detected by Western blot. The expression of miR-18a was down-regulated in the sputum and PDGF-BB-treated ASMCs of asthma patients. PDGF-BB could promote the proliferation and migration of ASMCs and inhibit their apoptosis; it could also promote the phenotypic transformation of ASMCs and activate the PI3K/AKT pathway. MiR-18a could inhibit the proliferation, migration ability and phenotypic transformation of ASMCs induced by PDGF-BB to a certain extent and alleviate the effect of PDGF-BB in supressing apoptosis, while miR-18a could inhibit the activation of the PI3K/AKT pathway. MiR-18a inhibits PDGF-BB-induced proliferation, migration and phenotypic conversion of ASMCs by inhibiting the PI3K/AKT pathway, thus attenuating airway remodeling in asthma.

Silencing of miR-10b-5p alleviates the mechanical stretch-induced proliferation of HASMCs

MicroRNAs (miRNAs) are important mediators to human airway smooth muscle cells (HASMCs) phenotype remodeling and airway diseases. MicroRNA-10b-5p (miR-10b-5p) has been extensively studied in different fields. This study set out to probe into the effect of miR-10b-5p in cyclic mechanical stretch-induced apoptosis in HASMCs. The results showed that after 15 % deformation, 0.5 s stretching and 0.5 s cyclic mechanical stretching relaxation (0.5 Hz) occurred to HASMCs, miR-10b-5p showed up-regulation without inducing significant apoptosis. Moreover, the mRNA and protein expressions of FLT1 were reduced. Then, dual-luciferase reporter assay verified that FLT1 was targeted by miR-10b-5p, and miR-10b-5p silencing increased FLT1 expression, leading to a prolonged arrest of stretch-treated HASMCs at the G1/S stage, and increased cell apoptosis compared with control group. Furthermore, the activity of Caspase-3 was reinforced, and the ratio of Bcl-2 to Bax was markedly reduced after miR-10b-5p silencing. The current study proved that expression levels of p-PI3K and p-Akt in stretch-treated HASMCs of the inhibition group were significantly inhibited in comparison to those of the controls. The effects of miR-10b-5p overexpression are opposite to that of inhibition of miR-10b-5p in stretched HASMCs. In conclusion, this study showed that miR-10b-5p silencing could weaken the hypertrophy of HASMCs. MiR-10b-5p negatively regulated FLT1 expression, but positively regulated the PI3K/Akt pathway in HASMCs. By referring to other previous studies, we concluded that miR-10b-5p might be a potent target in the treatment of airway diseases.

MiR-18a Inhibits PI3K/AKT Signaling Pathway to Regulate PDGF BB-Induced Airway Smooth Muscle Cell Proliferation and Phenotypic Transformation

The increased proliferation and migration of airway smooth muscle cells (ASMCs) is a key process in the formation of airway remodeling in asthma. In this study, we focused on the expression of mircoRNA-18a (miR-18a) in airway remodeling in bronchial asthma and its related mechanisms. ASMCs are induced by platelet-derived growth factor BB (PDGF-BB) for in vitro airway remodeling. The expression of miR-18a in sputum of asthmatic patients and healthy volunteers was detected by qRT-PCR. The expression of miR-18a was over-expressed or interfered with in PDGF-BB-treated ASMCs. Cell proliferation, apoptosis and migration were detected by MTT, flow cytometry and Transwell, respectively; the expression of contractile phenotype marker proteins (SM-22alpha, alpha-SM-actin, calponin) and key molecules of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway (PI3K, p-PI3K, AKT and p-AKT) in ASMCs were detected by Western blot. The expression of miR-18a was down-regulated in the sputum and PDGF-BB-treated ASMCs of asthma patients. PDGF-BB could promote the proliferation and migration of ASMCs and inhibit their apoptosis; it could also promote the phenotypic transformation of ASMCs and activate the PI3K/AKT pathway. MiR-18a could inhibit the proliferation, migration ability and phenotypic transformation of ASMCs induced by PDGF-BB to a certain extent and alleviate the effect of PDGF-BB in supressing apoptosis, while miR-18a could inhibit the activation of the PI3K/AKT pathway. MiR-18a inhibits PDGF-BB-induced proliferation, migration and phenotypic conversion of ASMCs by inhibiting the PI3K/AKT pathway, thus attenuating airway remodeling in asthma.

Role of miR-185-5p as modulator of periostin synthesis and smooth muscle contraction in asthma

Asthma is a chronic respiratory disease produced by an aberrant immune response that originates with breathing difficulties and cough, through airway remodeling. The above pathophysiological events of asthma emerge the regulators of effectors, like epigenetics, which include microRNAs (miRNAs) who perform post‐transcriptional regulation, controlling diverse pathways in respiratory diseases. The objective of the study was to determine how miR‐185‐5p regulates the secretion of periostin by airway structural cells, and smooth muscle cells contraction, both related to airway remodeling in asthma. We used miR‐185‐5p mimic and inhibitors in bronchial smooth muscle cells (BSMCs) and small airway epithelial cells (SAECs) from healthy subjects. Gene expression and protein levels of periostin (POSTN), CDC42, and RHOA were analyzed by RT‐PCR and ELISA/Western blot, respectively. BSMC contractility was analyzed using cell‐embedded collagen gels and measurement of intracellular calcium was performed using Fura‐2. Additionally, miR‐185‐5p and periostin expression were evaluated in sputum from healthy and asthmatics. From these experiments, we observed that miR‐185‐5p modulation regulates periostin mRNA and protein in BSMCs and SAECs. A tendency for diminished miR‐185‐5p expression and higher periostin levels was seen in sputum cells from asthmatics compared to healthy, with an inverse correlation observed between POSTN and miR‐185‐5p. Inhibition of miR‐185‐5p produced higher BSMCs contraction induced by histamine. Calcium mobilization was not modified by miR‐185‐5p, showing that miR‐185‐5p role in BSMC contractility is performed by regulating CDC42 and RhoA pro‐contractile factors instead. In conclusion, miR‐185‐5p is a modulator of periostin secretion by airway structural cells and of smooth muscle contraction, which can be related to asthma pathophysiology, and thus, might be a promising therapeutic target.

Oxidative Stress Promotes Corticosteroid Insensitivity in Asthma and COPD

Corticosteroid insensitivity is a key characteristic of patients with severe asthma and COPD. These individuals experience greater pulmonary oxidative stress and inflammation, which contribute to diminished lung function and frequent exacerbations despite the often and prolonged use of systemic, high dose corticosteroids. Reactive oxygen and nitrogen species (RONS) promote corticosteroid insensitivity by disrupting glucocorticoid receptor (GR) signaling, leading to the sustained activation of pro-inflammatory pathways in immune and airway structural cells. Studies in asthma and COPD models suggest that corticosteroids need a balanced redox environment to be effective and to reduce airway inflammation. In this review, we discuss how oxidative stress contributes to corticosteroid insensitivity and the importance of optimizing endogenous antioxidant responses to enhance corticosteroid sensitivity. Future studies should aim to identify how antioxidant-based therapies can complement corticosteroids to reduce the need for prolonged high dose regimens in patients with severe asthma and COPD.

SET knockdown attenuated phenotype modulation and calcium channel associated markers of airway smooth muscle cells in asthmatic mice

Background

Dysfunctional phenotype modulation and calcium channels in airway smooth muscle cells (ASMCs) are important characteristics of airway remodeling in chronic asthma. However, the mechanisms underlying these pathological processes remain unclear. SET (I2PP2A, inhibitor-2 of protein phosphatase 2A) has many significant functions and is involved in various physiological and pathological processes. This study aimed to determine the function of SET in chronic asthma.

Methods

BALB/c mice were sensitized by ovalbumin injection and repeated inhalation of ovalbumin. The Penh value was measured using the Buxco whole body plethysmography system. A short hairpin RNA of the SET gene was designed and transfected into ASMCs derived from asthmatic mice. Flow cytometry of Annexin-V/propidium iodide staining was used for evaluating cell apoptosis. Western blot was adopted to measure the expression levels of ASMCs phenotype modulation markers and calcium channel-associated proteins.

Results

The results showed that shRNA targeting SET significantly decreased the expression of SET, and enhanced the apoptosis of ASMCs. SET knockdown promoted the expression of contractile phenotype markers such as α-SMA (alpha smooth muscle Actin), SM-MHC (smooth muscle Myosin heavy chain), and calponin, and inhibited the expression of synthetic phenotype markers including vimentin and CD44. The expression of the calcium channel-related proteins STIM1 (Stromal interaction molecule 1) and Orai1 were also inhibited after SET knockdown.

Conclusions

These data demonstrated that SET participated in the development of airway dysfunction in asthma, suggesting that the silencing of SET may be a new therapeutic target for the treatment of asthma patients.

LncRNA H19 Inhibits Proliferation and Migration of Airway Smooth Muscle Cells Induced by PDGF-BB Through miR-21/PTEN/Akt Axis

Background

LncRNA H19 expression is down-regulated in patients with asthma. The hyperplasia of airway smooth muscle cells (ASMCs) promotes the development of airway remodeling in asthma. Therefore, we attempted to evaluate the regulatory function of H19 in the proliferation and migration of ASMCs.

Methods

The expressions of H19 and miR-21 were detected using qRT-PCR. PDGF-BB-induced abnormal proliferation and migration of ASMCs was used as the airway remodeling model in vitro. The expressions of H19 and miR-21 were modified by transfection with pcDNA3.1-H19 and miR-21 mimic, respectively. CCK-8 assay, flow cytometry-based cell cycle analysis was conducted to examine the proliferation ability of ASMCs. The migration ability was measured by transwell assay. Dual-luciferase reporter system was carried out to find the potential relationship between miR-21 and H19 or PTEN. Western blot was conducted to detect the expressions of PCNA, MMP-9, α-SMA, PTEN, and the phosphorylation level of Akt.

Results

LncRNA-H19 expression was decreased and microRNA-21 expression was increased in serum samples of children with asthma and PDGF-BB-stimulated ASMCs. Overexpression of H19 reduced the proliferation and migration ability of ASMCs with PDGF-BB treatment and these changes were reversed by miR-21 mimic. H19 promoted the protein level of PTEN via sponging miR-21. Overexpression of H19 suppressed miR-21-induced phosphorylation of Akt, and the suppression effect of H19 on phosphorylation of Akt was significantly reduced after transfecting shPTEN in ASMCs.

Conclusion

In this study, overexpression of H19 suppressed the proliferation and migration of ASMCs induced by PDGF-BB via miR-21/PTEN/Akt axis, which could be a potential biomarker and target for treating hyperplasia of airway smooth muscle cells.

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

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

Transcriptomic analysis delineates potential signature genes and miRNAs associated with the pathogenesis of asthma

Asthma is a multifarious disease affecting several million people around the world. It has a heterogeneous risk architecture inclusive of both genetic and environmental factors. This heterogeneity can be utilised to identify differentially expressed biomarkers of the disease, which may ultimately aid in the development of more localized and molecularly targeted therapies. In this respect, our study complies with meta-analysis of microarray datasets containing mRNA expression profiles of both asthmatic and control patients, to identify the critical Differentially Expressed Genes (DEGs) involved in the pathogenesis of asthma. We found a total of 30 DEGs out of which 13 were involved in the pathway and functional enrichment analysis. Moreover, 5 DEGs were identified as the hub genes by network centrality-based analysis. Most hub genes were involved in protease/antiprotease pathways. Also, 26 miRNAs and 20 TFs having an association with these hub genes were found to be intricated in a 3-node miRNA Feed-Forward Loop. Out of these, miR-34b and miR-449c were identified as the key miRNAs regulating the expression of SERPINB2 gene and SMAD4 transcription factor. Thus, our study is suggestive of certain miRNAs and unexplored pathways which may pave a way to unravel critical therapeutic targets in asthma.

Pulmonary delivery of ORMDL3 short hairpin RNA - a potential tool to regulate allergen-induced airway inflammation

Aim/Purpose: Exposure to various allergens has been shown to increase expression of ORMDL3 in the lung in models of allergic asthma. Studies using genetically modified (transgenic or knock out) mice have revealed some of the functions of ORMDL3 in asthma pathogenesis, although amid debate. The goal of this study was to use targeted post-transcriptional downregulation of ORMDL3 in allergen-challenged wild-type (WT) mice by RNA interference to further elucidate the functional role of ORMDL3 in asthma pathogenesis and evaluate a potential therapeutic option.Methods: Allergen (ovalbumin [OVA])-challenged WT mice were administered intranasally (i.n) with a single dose of five short hairpin RNA (shRNA) constructs with different target sequence for murine ORMDL3 cloned in a lentiviral vector or with the empty vector (control). Mice were evaluated for allergen-induced airway hyperresponsiveness (AHR) and various features of airway inflammation after 72 hours.Results: I.n administration of a single dose of ORMDL3 shRNAs to OVA-challenged mice resulted in reduction of ORMDL3 gene expression in the lungs associated with a significant reduction in AHR to inhaled methacholine and in the number of inflammatory cells recruited in the airways, specifically eosinophils, as well as in airway mucus secretion compared to OVA-challenged mice that received the empty vector. Administration of ORMDL3 shRNAs also significantly inhibited levels of IL-13, eotaxin-2 and sphingosine in the lungs. Additionally, ORMDL3 shRNAs significantly inhibited the allergen-mediated increase in monohexyl ceramides C22:0 and C24:0.Conclusions: Post-transcriptional down regulation of ORMDL3 in allergic lungs using i.n-delivered ORMDL3 shRNA (akin to inhaled therapy) attenuates development of key features of airway allergic disease, confirming the involvement of ORMDL3 in allergic asthma pathogenesis and serving as a model for a potential therapeutic strategy.

Long-Term Sequelae of Smoking and Cessation in Spontaneously Hypertensive Rats

Smoking is a major risk factor for heart attack, stroke, and lung cancer. Tobacco smoke (TS) causes bronchitis, emphysema, persistent cough, and dyspnea. Smoking cessation minimizes risks of TS-related disease. To determine whether smoking cessation could reverse TS-induced pulmonary changes, 10-week-old male spontaneously hypertensive rats were exposed to TS or filtered air (FA) for 39 weeks and allowed to live out their normal lifespan. Significantly (P ≤ .05) decreased survival was noted by 21 months in TS versus FA rats. In TS rats, persistent peribronchiolar, perivascular, alveolar, and subpleural inflammation were observed with pervasive infiltration of pigmented foamy macrophages and plausible intra-alveolar fibrosis and osseous metaplasia. Alveolar airspace was significantly (P ≤ .05) increased in TS versus FA rats as was the volume of stored epithelial mucosubstances in the left central axial airway. Increased mucin contributes to airflow obstruction and increased lung infection risks. Findings suggest TS-induced changes do not attenuate with smoking cessation but result in irreversible damage similar to chronic obstructive pulmonary disease. The observed persistent pulmonary changes mirror common TS effects such as chest congestion, sputum production, and shortness of breath long after smoking cessation and represent important targets for treatment of former smokers.

Esculetin regulates the phenotype switching of airway smooth muscle cells

Airway remodeling is one important feature of childhood asthma, which is one of the most common chronic childhood diseases. Phenotype switching of airway smooth muscle cells (ASMCs), defined as a reversible switching between contractile and proliferative phenotypes, plays an important role in the process of airway remodeling. Esculetin has shown antiinflammatory action in animal models of asthma; however, the effects of esculetin on ASMC phenotype switching have not been investigated. In the present study, platelet-derived growth factor (PDGF) was used to induce the phenotype modulation of ASMCs. The results demonstrated that esculetin pretreatment mitigated the PDGF-caused inhibitory effects on expressions of contractile phenotype protein markers, including calponin and SM22α. Esculetin also inhibited PDGF-induced migration and proliferation of ASMCs. Besides, the PDGF-induced expressions of extracellular matrix components, collagen I and fibronectin, were attenuated by esculetin pretreatment. Furthermore, PDGF-caused activation of PI3K/Akt pathway in ASMCs was inhibited by esculetin. These findings suggest that esculetin might exert its inhibitory effect on PDGF-induced ASMC phenotype switching through inhibition of PI3K/Akt pathway.

Rho-kinase inhibitor attenuates airway mucus hypersecretion and inflammation partly by downregulation of IL-13 and the JNK1/2-AP1 signaling pathway

We measured the effect of Rho-kinase on inflammation and mucus hypersecretion in the airways of mouse models of asthma. Additionally, we aimed to determine if these effects were the result of JNK 1/2-AP1 pathway inhibition.We sensitized and challenged female C57BL/6 mice using house dust mites (HDM) followed by treatment with an inhibitor of Rho-kinase. Lung tissue was harvested to evaluate inflammation and mucus secretion in the airways of asthma mice. Cytokine expression in broncho-alveolar lavage fluid (BALF) was established by ELISA and airway responsiveness, and was determined by the invasive lung function test. JNK1/2, p-JNK1/2, AP-1, and p-AP-1 protein expression was determined by Western blot analysis. Asthma model mice that were treated with Rho-kinase inhibitor showed a significantly decrease in inflammation score, inflammatory cells, and airway responsiveness. Additionally, we found that IL-13 expressions in BALF and mucus secretion were decreased in HDM-challenged mice treated with Rho-kinase inhibitor. Furthermore, Rho-kinase inhibitor treatment decreased the expression of JNK1/2 and AP-1 phosphorylation. Our findings indicated that the Rho-kinase inhibitor decreased HDM-induced mucus secretion as well as airway inflammation in asthma mice through regulation of the JNK1/2-AP-1 pathway.

Interference of miR-943-3p with secreted frizzled-related proteins4 (SFRP4) in an asthma mouse model

The aim of this study is to investigate the potential roles of miR-943-3p and its target gene secreted frizzled-related proteins4 (SFRP4) in allergic asthma and elucidate its underlying mechanism, which may prompt a new clue about developing novel treatments of this disease. An allergic asthma mouse model was generated by challenging with ovalbumin (OVA); lung pathological features of mice were viewed using H&E staining; thickness of subepithelial fibrosis and smooth muscle was measured using Masson's trichrome staining. Inflammatory cells from bronchoalveolar lavage fluid (BALF) were counted based on Diff-Quik staining and morphometric analysis. Expressions of miR-943-3p, SFRP4 and Wnt signal pathway-associated proteins were detected using RT-PCR or immunoblotting, respectively. SFRP4 was downregulated in the bronchial biopsies of allergic asthma patients and represented a unique intersection between differentially expressed genes (DEGs) and genes in the Wnt signal pathway. Both miR-943-3p upregulation and SFRP4 downregulation were detected in allergic asthma patients and OVA-induced mice. Besides, OVA-induced mice possessed more inflammatory cells in BALF including macrophage (mac), eosinophil (eos), lymphocyte (lym) and neutrophil (neu), higher expression of collagen, β-catenin and c-Myc as well as thicker subepithelial fibrosis and smooth muscle in lung than control mice. In vivo delivery of miR-943-3p agomir worsened these symptoms, while both miR-943-3p antagomir and Ad-SFRP4 administration effectively alleviated this disease. Taken together, miR-943-3p accelerated the progression of airway inflammation and remodeling in allergic asthma via suppressing the activity of SFRP4 through Wnt signaling pathway in asthma patients and OVA-induced mice.

Silencing of ADAM33 restrains proliferation and induces apoptosis of airway smooth muscle cells in ovalbumin-induced asthma model

A defibrinogen and metalloproteinase 33 (ADAM33) was reported to play an important role in asthma. Furthermore, ADAM33 may play a possible role in airway remodeling due to its high expression in myo-/fibroblasts, epithelium, as well as the airway smooth muscle cells (ASMCs). Thus, the study is supposed to investigate the effect of the downregulation of ADAM33 on the proliferation and apoptosis of ASMCs in allergic asthma. An ovalbumin-induced asthma model in rats was established for investigating the function of the silencing of ADAM33. ASMCs were cultured and divided into four groups after transfection. The messenger RNA and protein expressions of ADAM33 were measured by reverse transcription quantitative polymerase chain reaction and Western blot analysis. Cell proliferation was tested by cell counting kit-8 and cell apoptosis by TdT-mediated dUTP nick-end labeling. The allergic asthma rats showed a large number of inflammatory cell infiltration, airway smooth muscle hypertrophy and hyperplasia, and increased WA _t , WA _m , and numbers of bronchial smooth muscle nucleus. Additionally, increased numbers of eosinophils and neutrophils, expressions of immunoglobulin E and interleukin-4, content of airway air pressure, and NO, although decreased in expression of interferon-γ, were exhibited in rats with allergic asthma. In our study, upregulated ADAM33 was found, and after the silencing of ADAM33, decreased proliferation and increased apoptosis of ASMCs were observed. The study evidences that silencing of ADAM33 can decrease the proliferation and increase the apoptosis of ASMCs in a rat model of allergic asthma, suggesting ADAM33 represents a potential investigative focus target aiding allergic asthma.

Neutrophils induce smooth muscle hyperplasia via neutrophil elastase-induced FGF-2 in a mouse model of asthma with mixed inflammation

BACKGROUND

Bronchial asthma is traditionally characterized by chronic allergic inflammation, including eosinophilia and elevated Th2 cytokines. Recently, IL-17-derived neutrophil infiltration was shown to correlate with asthma severity and airway remodelling.

OBJECTIVE

To investigate the role of IL-17-derived neutrophils in airway remodelling in chronic bronchial asthma.

METHODS

We utilized house dust mite antigen-induced mouse models of asthma. Intranasal sensitization and chronic antigen challenge caused a mixed allergic inflammation that included eosinophils and neutrophils (Mix-in group). We neutralized IL-17 and fibroblast growth factor (FGF-2) and investigated the mechanism of airway remodelling in the Mix-in group.

RESULTS

The Mix-in group displayed neutrophilic infiltration and high levels of IL-17 in lung tissue. The Mix-in group also exhibited more bronchial smooth muscle hyperplasia. IL-17 neutralization decreased the magnitude of all of these effects in the Mix-in group. Antibody arrays revealed an increase in FGF-2 in the Mix-in Group relative to the Eo-ip group, and FGF-2 elevation was associated with smooth muscle hypertrophy/hyperplasia. High concentrations of neutrophil elastase enhanced E-cadherin/β-catenin signalling in bronchial epithelial cells. Neutrophil elastase inhibitor treatment decreased FGF-2 production and E-cadherin/β-catenin signalling, which inhibited smooth muscle hyperplasia.

CONCLUSION

The IL-17/neutrophil axis may play an important role in airway remodelling by contributing to smooth muscle hypertrophy/hyperplasia in mixed allergic inflammation and accordingly represents an attractive therapeutic target for severe asthma.

Regulation of eosinophil recruitment and allergic airway inflammation by heparan sulfate proteoglycan (HSPG) modifying enzymes

BACKGROUND

HSPGs are glycoproteins containing covalently attached heparan sulfate (HS) chains which bind to growth factors, chemokines, etc., and regulate various aspects of inflammation including cell recruitment. We previously showed that deletion of endothelial N-acetylglucosamine N-deacetylase-N-sulfotransferase-1 (Ndst1), an enzyme responsible for N-sulfation during HS biosynthesis, reduces allergic airway inflammation (AAI). Here, we investigated the importance of O-sulfation mediated by uronyl 2-O-sulfotransferase (Hs2st) in development of AAI relative to N-sulfation.

METHODS

Mice deficient in endothelial and leukocyte Hs2st (Hs2st^f/fTie2Cre⁺) or Ndst1 (Ndst1^f/fTie2Cre⁺) and WT mice were challenged with Alternaria alternata and evaluated for airway inflammation. Trafficking of murine eosinophils on lung endothelial cells was examined in vitro under conditions of flow.

RESULTS

Exposure to Alternaria decreased expression level of Hs2st in WT mice while level of Ndst1 remained unchanged. Compared to WT mice, Alternaria-challenged Hs2st^f/fTie2Cre⁺ mice exhibited significantly increased eosinophils in the bone marrow, bronchoalveolar lavage fluid [BALF] and lung tissue associated with persistent airway hyperresponsiveness, airway mucus hypersecretion and elevated Th2 cytokines. In contrast, Alternaria-challenged Ndst1^f/fTie2Cre⁺ mice exhibited a marked reduction in airway eosinophilia, mucus secretion and smooth muscle mass compared to WT counterparts. While BALF eotaxins were lower in Alternaria-challenged Hs2st^f/fTie2Cre⁺ relative to WT mice, they were not reduced to background levels as in allergen-challenged Ndst1^f/fTie2Cre⁺ mice. Trafficking of murine eosinophils under conditions of flow in vitro was similar on Hs2st-deficient and WT endothelial cells. Expression of ZO-1 in Hs2st-deficient lung blood vessels in control and allergen-challenged mice was significantly lower than in WT counterparts.

CONCLUSIONS

Our study demonstrates that allergen exposure reduces expression of Hs2st; loss of uronyl 2-O-sulfation in endothelial and leukocyte HSPG amplifies recruitment of eosinophils likely due to a compromised vascular endothelium resulting in persistent inflammation whereas loss of N-sulfation limits eosinophilia and attenuates inflammation underscoring the importance of site-specific sulfation in HSPG to their role in AAI.

An Official American Thoracic Society Research Statement: Current Challenges Facing Research and Therapeutic Advances in Airway Remodeling

BACKGROUND

Airway remodeling (AR) is a prominent feature of asthma and other obstructive lung diseases that is minimally affected by current treatments. The goals of this Official American Thoracic Society (ATS) Research Statement are to discuss the scientific, technological, economic, and regulatory issues that deter progress of AR research and development of therapeutics targeting AR and to propose approaches and solutions to these specific problems. This Statement is not intended to provide clinical practice recommendations on any disease in which AR is observed and/or plays a role.

METHODS

An international multidisciplinary group from within academia, industry, and the National Institutes of Health, with expertise in multimodal approaches to the study of airway structure and function, pulmonary research and clinical practice in obstructive lung disease, and drug discovery platforms was invited to participate in one internet-based and one face-to-face meeting to address the above-stated goals. Although the majority of the analysis related to AR was in asthma, AR in other diseases was also discussed and considered in the recommendations. A literature search of PubMed was performed to support conclusions. The search was not a systematic review of the evidence.

RESULTS

Multiple conceptual, logistical, economic, and regulatory deterrents were identified that limit the performance of AR research and impede accelerated, intensive development of AR-focused therapeutics. Complementary solutions that leverage expertise of academia and industry were proposed to address them.

CONCLUSIONS

To date, numerous factors related to the intrinsic difficulty in performing AR research, and economic forces that are disincentives for the pursuit of AR treatments, have thwarted the ability to understand AR pathology and mechanisms and to address it clinically. This ATS Research Statement identifies potential solutions for each of these factors and emphasizes the importance of educating the global research community as to the extent of the problem as a critical first step in developing effective strategies for: (1) increasing the extent and impact of AR research and (2) developing, testing, and ultimately improving drugs targeting AR.

Autophagy in airway diseases: a new frontier in human asthma?

The study of autophagy ('self-eating'), a fundamental cell fate pathway involved in physiological and pathological subcellular processes, opens a new frontier in the continuous search for novel therapies for human asthma. Asthma is a complex syndrome with different disease phenotypes. Autophagy plays a central role in cell physiology, energy and metabolism, and cell survival. Autophagy's hallmark is the formation of double-membrane autophagic autophagosomes, and this process is operational in airway epithelial and mesenchymal cells in asthma. Genetic associations between autophagy genes and asthma have been observed including single nucleotide polymorphisms in Atg5 which correlate with reduced lung function. Immune mechanisms important in asthma such as Th2 cells and eosinophils also manifest autophagy. Lastly, we address the role of autophagy in extracellular matrix deposition and fibrosis in asthmatic airways remodeling, a pathologic process still without effective therapy, and discuss potential pharmacologic inhibitors. We end by offering two opposing but plausible hypotheses as to how autophagy may be directly involved in airway fibrosis.

Kaempferol Inhibits Endoplasmic Reticulum Stress-Associated Mucus Hypersecretion in Airway Epithelial Cells And Ovalbumin-Sensitized Mice

Mucus hypersecretion is an important pathological feature of chronic airway diseases, such as asthma and pulmonary diseases. MUC5AC is a major component of the mucus matrix forming family of mucins in the airways. The initiation of endoplasmic reticulum (ER)-mediated stress responses contributes to the pathogenesis of airway diseases. The present study investigated that ER stress was responsible for airway mucus production and this effect was blocked by the flavonoid kaempferol. Oral administration of ≥10 mg/kg kaempferol suppressed mucus secretion and goblet cell hyperplasia observed in the bronchial airway and lung of BALB/c mice sensitized with ovalbumin (OVA). TGF-β and tunicamycin promoted MUC5AC induction after 72 h in human bronchial airway epithelial BEAS-2B cells, which was dampened by 20 μM kaempferol. Kaempferol inhibited tunicamycin-induced ER stress of airway epithelial cells through disturbing the activation of the ER transmembrane sensor ATF6 and IRE1α. Additionally, this compound demoted the induction of ER chaperones such as GRP78 and HSP70 and the splicing of XBP-1 mRNA by tunicamycin. The in vivo study further revealed that kaempferol attenuated the induction of XBP-1 and IRE1α in epithelial tissues of OVA-challenged mice. TGF-β and tunicamycin induced TRAF2 with JNK activation and such induction was deterred by kaempferol. The inhibition of JNK activation encumbered the XBP-1 mRNA splicing and MUC5AC induction by tunicamycin and TGF-β. These results demonstrate that kaempferol alleviated asthmatic mucus hypersecretion through blocking bronchial epithelial ER stress via the inhibition of IRE1α-TRAF2-JNK activation. Therefore, kaempferol may be a potential therapeutic agent targeting mucus hypersecretion-associated pulmonary diseases.

Acute high-level exposure to WTC particles alters expression of genes associated with oxidative stress and immune function in the lung

First responders (FR) present at Ground Zero in the first 72 h after the World Trade Center (WTC) collapsed have progressively exhibited significant respiratory injuries. The few toxicology studies performed to date evaluated effects from just fine (< 2.5 µm) WTC dusts; none examined health effects/toxicities from atmospheres bearing larger particle sizes, despite the fact the majority (> 96%) of dusts were > 10 µm and most FR likely entrained dusts by mouth breathing. Using a system that generated/delivered supercoarse (10-53 µm) WTC dusts to F344 rats (in a manner that mimicked FR exposures), this study sought to examine potential toxicities in the lungs. In this exploratory study, rats were exposed for 2 h to 100 mg WTC dust/m(3) (while under isoflurane [ISO] anesthesia) or an air/ISO mixture; this dose conservatively modeled likely exposures by mouth-breathing FR facing ≈750-1000 mg WTC dust/m(3). Lungs were harvested 2 h post-exposure and total RNA extracted for subsequent global gene expression analysis. Among the >  1000 genes affected by WTC dust (under ISO) or ISO alone, 166 were unique to the dust exposure. In many instances, genes maximally-induced by the WTC dust exposure (relative to in naïve rats) were unchanged/inhibited by ISO only; similarly, several genes maximally inhibited in WTC dust rats were largely induced/unchanged in rats that received ISO only. These outcomes reflect likely contrasting effects of ISO and the WTC dust on lung gene expression. Overall, the data show that lungs of rats exposed to WTC dust (under ISO) - after accounting for any impact from ISO alone - displayed increased expression of genes related to lung inflammation, oxidative stress, and cell cycle control, while several involved in anti-oxidant function were inhibited. These changes suggested acute inflammogenic effects and oxidative stress in the lungs of WTC dust-exposed rats. This study, thus, concludes that a single very high exposure to WTC dusts could potentially have adversely affected the respiratory system - in terms of early inflammatory and oxidative stress processes. As these changes were not compared with other types of dusts, the uniqueness of these WTC-mediated effects remains to be confirmed. It also still remains to be determined if these effects might have any relevance to chronic lung pathologies that became evident among FR who encountered the highest dust levels on September 11, 2001 and the 2 days thereafter. Ongoing studies using longer-range post-exposure analyses (up to 1-year or more) will help to determine if effects seen here on genes were acute, reversible, or persistent, and associated with corresponding histopathologic/biochemical changes in situ.

Inhibition of airway epithelial-to-mesenchymal transition and fibrosis by kaempferol in endotoxin-induced epithelial cells and ovalbumin-sensitized mice

Chronic airway remodeling is characterized by structural changes within the airway wall, including smooth muscle hypertrophy, submucosal fibrosis and epithelial shedding. Epithelial-to-mesenchymal transition (EMT) is a fundamental mechanism of organ fibrosis, which can be induced by TGF-β. In the in vitro study, we investigated whether 1-20 μM kaempferol inhibited lipopolysaccharide (LPS)-induced bronchial EMT in BEAS-2B cells. The in vivo study explored demoting effects of 10-20 mg/kg kaempferol on airway fibrosis in BALB/c mice sensitized with ovalbumin (OVA). LPS induced airway epithelial TGF-β1 signaling that promoted EMT with concurrent loss of E-cadherin and induction of α-smooth muscle actin (α-SMA). Nontoxic kaempferol significantly inhibited TGF-β-induced EMT process through reversing E-cadherin expression and retarding the induction of N-cadherin and α-SMA. Consistently, OVA inhalation resulted in a striking loss of epithelial morphology by displaying myofibroblast appearance, which led to bronchial fibrosis with submucosal accumulation of collagen fibers. Oral administration of kaempferol suppressed collagen deposition, epithelial excrescency and goblet hyperplasia observed in the lung of OVA-challenged mice. The specific inhibition of TGF-β entailed epithelial protease-activated receptor-1 (PAR-1) as with 20 μM kaempferol. The epithelial PAR-1 inhibition by SCH-79797 restored E-cadherin induction and deterred α-SMA induction, indicating that epithelial PAR-1 localization was responsible for resulting in airway EMT. These results demonstrate that dietary kaempferol alleviated fibrotic airway remodeling via bronchial EMT by modulating PAR1 activation. Therefore, kaempferol may be a potential therapeutic agent targeting asthmatic airway constriction.

High-fat diet promotes lung fibrosis and attenuates airway eosinophilia after exposure to cockroach allergen in mice

Obesity is an important risk factor for asthma but the mechanistic basis for this association is not well understood. In the current study, the impact of obesity on lung inflammatory responses after allergen exposure was investigated. C57BL/6 mice maintained on a high-fat diet (HFD) or a normal diet (ND) after weaning were sensitized and challenged with cockroach allergen (CRA). Airway inflammation was assessed based on inflammatory cell recruitment, measurement of lung Th1-Th2 cytokines, chemokines, eicosanoids, and other proinflammatory mediators as well as airway hyperresponsiveness (AHR). CRA-challenged mice fed a HFD exhibited significantly decreased allergen-induced airway eosinophilia along with reduced lung IL-5, IL-13, LTC4, CCL11, and CCL2 levels as well as reduced mucus secretion and smooth muscle mass compared to ND fed mice. However, allergen-challenged HFD fed mice demonstrated significantly increased PAI-1 and reduced PGE2 levels in the lung relative to corresponding ND fed mice. Interestingly, saline-exposed HFD fed mice demonstrated elevated baseline levels of TGF-β1, arginase-1, hypoxia-inducible factor-1α, and lung collagen expression associated with decreased lung function compared to corresponding ND fed mice. These studies indicate that a HFD inhibits airway eosinophilia while altering levels of PAI-1 and PGE2 in response to CRA in mice. Further, a HFD can lead to the development of lung fibrosis even in the absence of allergen exposure which could be due to innate elevated levels of specific profibrotic factors, potentially affecting lung function during asthma.

Dexamethasone reduces bronchial wall remodeling during pulmonary migration of Strongyloides venezuelensis larvae in rats

Strongyloidiasis is an intestinal parasitosis with an obligatory pulmonary cycle. A Th2-type immune response is induced and amplifies the cellular response through the secretion of inflammatory mediators. Although this response has been described as being similar to asthma, airway remodeling during pulmonary migration of larvae has not yet been established. The aim of this study was to identify the occurrence of airway remodeling during Strongyloides venezuelensis (S. v.) infection and to determine the ability of dexamethasone treatment to interfere with the mechanisms involved in this process. Rats were inoculated with 9,000 S. v. larvae, treated with dexamethasone (2 mg/kg) and killed at 1, 3, 5, 7, 14 and 21 days. Morphological and morphometric analyzes with routine stains and immunohistochemistry were conducted, and some inflammatory mediators were evaluated using ELISA. Goblet cell hyperplasia and increased bronchiolar thickness, characterized by edema, neovascularization, inflammatory infiltrate, collagen deposition and enlargement of the smooth muscle cell layer were observed. VEGF, IL1-β and IL-4 levels were elevated throughout the course of the infection. The morphological findings and the immunomodulatory response to the infection were drastically reduced in dexamethasone-treated rats. The pulmonary migration of S. venezuelensis larvae produced a transitory, but significant amount of airway remodeling with a slight residual bronchiolar fibrosis. The exact mechanisms involved in this process require further study.

Autocrine-regulated airway smooth muscle cell migration is dependent on IL-17-induced growth-related oncogenes

BACKGROUND

Airway smooth muscle cell (ASMC) migration is one of the proposed mechanisms underlying the increased airway smooth muscle mass seen in airway remodeling of patients with severe asthma. IL-17-related cytokines are a new subgroup of inflammatory mediators that have been suggested to play a role in regulating smooth muscle function. We hypothesized that IL-17-induced chemokine production from smooth muscle cells can contribute to migration of additional smooth muscle cells in the airways of asthmatic patients.

OBJECTIVE

We sought to investigate the effect of IL-17 on smooth muscle-derived chemokines and to examine the mechanisms involved in their production and contribution to the increase in airway smooth muscle migration.

METHODS

The effect of IL-17-induced supernatants on human ASMC migration was investigated. IL-17-induced growth-related oncogene (GRO) production and mRNA expression was assessed by using ELISA and RT-PCR, respectively. The direct effect of GROs on ASMC migration and the involvement of the CXCR2 receptor were also examined.

RESULTS

IL-17-induced supernatants promoted ASMC migration. After IL-17 stimulation, GROs were the most abundant chemokines produced from ASMCs, and blocking their effect by using neutralizing antibodies significantly inhibited ASMC migration. In addition, a combination of recombinant human GRO-α, GRO-β, and GRO-γ was able to promote significant migration of ASMCs that was mediated through the CXCR2 receptor.

CONCLUSION

These findings suggest that IL-17-induced GROs can be an important mediator of ASMC migration and therefore might contribute to the pathogenesis of airway remodeling in asthmatic patients.

IκB kinase β inhibitor IMD-0354 suppresses airway remodelling in a Dermatophagoides pteronyssinus-sensitized mouse model of chronic asthma

BACKGROUND

Nuclear factor (NF)-κB is a transcription factor that regulates cytokine and chemokine production in various inflammatory diseases, including bronchial asthma. IκB kinase (IKK) β is important for NF-κB activation in inflammatory conditions, and is possibly related to airway remodelling. Thus, inhibition of the IKKβ-NF-κB pathway may be an ideal strategy for the management of airway remodelling.

OBJECTIVE

We examined the effects of a newly synthesized IKKβ inhibitor, IMD-0354, in a chronic allergen exposure model of bronchial asthma in mice.

METHODS

A chronic mouse model was generated by challenge with house dust mite antigen (Dermatophagoides pteronyssinus). IMD-0354 was administrated intraperitoneally in therapeutic groups. Lung histopathology, hyperresponsiveness and the concentrations of mediators and molecules in supernatants of lung homogenates were determined.

RESULTS

NF-κB activation was inhibited by prolonged periods of IMD-0354 administration. IMD-0354 reduced the numbers of bronchial eosinophils. IMD-0354 also inhibited the pathological features of airway remodelling, including goblet cell hyperplasia, subepithelial fibrosis, collagen deposition and smooth muscle hypertrophy. Inhibition of these structural changes by IMD-0354 was the result of the suppressing the production and activation of remodelling-related mediators, such as TGF-β, via inhibition of IKKβ. IMD-0354 inhibited IL-13 and IL-1β production, and it restored the production of IFN-γ. It also ameliorated airway hyperresponsiveness.

CONCLUSION

IKKβ plays crucial roles in airway inflammation and remodelling in a chronic mouse model of asthma. A specific IKKβ inhibitor, IMD-0354, may be therapeutically beneficial for treating airway inflammation and remodelling in chronic asthma.

shRNA targeting β1-integrin suppressed proliferative aspects and migratory properties of airway smooth muscle cells

Dysfunction of airway smooth muscle (ASM) is an essential feature of airway remodeling in chronic asthma. However, the precise mechanisms of this pathological process have not been well studied. In previous study, we found that β1-integrin, which was dramatically upregulated in ASM cells in an asthmatic mouse model, was associated with the cell proliferation. In this study, we employed short hairpin RNA (shRNA) targeting β1-integrin to assess the effect of down-regulation of this receptor on the proliferative aspects and migratory properties of ASM cells in vitro. The cells were treated with shRNA expression vectors directed against β1-integrin, control vectors that included the blank control, empty vector without shRNA, and mismatched shRNA, respectively. The mRNA and protein expressions of β1-integrin were determined by real-time PCR and Western blotting. Cell proliferation was measured by BrdU ELISA and cell cycle by fluorescence-activated cell sorter. Cell apoptosis was detected by Annexin V-PE/7-AAD staining. Cell migration assays were evaluated by transwell assay and expression of IL-6 and IL-8 by ELISA. The results revealed that shRNA targeting β1-integrin significantly decreased the mRNA and protein expressions of β1-integrin, enhanced the proportion of cells in G0/G1 phase, decreased the proportion in S phase, promoted cell apoptosis, inhibited cell proliferation, migration, IL-6 and IL-8 secretion in vitro. In conclusion, the overexpression of β1-integrin in ASM cells is essential for airway dysfunction development because it promotes proliferative aspects and migratory properties of ASM cells. Importantly, shRNA targeting β1-integrin may provide a new approach to preventing airway remodeling in chronic asthma.

The role of bone marrow-derived adult stem cells in a transgenic mouse model of allergic asthma

BACKGROUND

Asthmatic airway remodeling is an abnormal injury/repair process of the small airways caused by chronic inflammation in which the quantities of multiple cells increase dramatically. However, the origin of these proliferative cells is still undetermined.

OBJECTIVE

The aim of this study was to examine whether bone marrow (BM)-derived adult stem cells are responsible for the proliferative cells in asthmatic airway remodeling.

METHODS

Adult mice were durably engrafted with BM isolated from green fluorescent protein (GFP) transgenic mice. Using GFP BM chimera mice, an ovalbumin (OVA)-induced chronic asthma mouse model was established. The distribution of BM-derived GFP+ cells in the lungs of chronic asthma mice was detected by fluorescence microscopy. The phenotype of BM-derived GFP+ cells in the lung tissues of chronic asthma mice was analyzed by flow cytometry.

RESULTS

BM chimera mice were successfully generated, with no detectable radioactive inflammation observed. Using BM chimera mice, we established a mouse model of chronic asthma characterized by a significant increase in the thickness of the airway subepithelial basement membrane and smooth muscle layers. OVA treatment caused many GFP+ cells to appear at sites of small airway inflammation. The extravascular localization of some GFP+ cells and their morphology were not consistent with leukocytes. Flow cytometric analysis of lung cells revealed a significant increase in type I collagen (Col I)+GFP+ cells and α-smooth muscle actin (α-SMA)+GFP+ cells in OVA-treated GFP BM chimera mice.

CONCLUSIONS

Considerable numbers of Col I- and α-SMA-producing cells originated from BM in the lung tissues of mice with OVA-induced chronic asthma.

Beta-agonist-associated reduction in RGS5 expression promotes airway smooth muscle hyper-responsiveness

Although short-acting and long-acting inhaled β(2)-adrenergic receptor agonists (SABA and LABA, respectively) relieve asthma symptoms, use of either agent alone without concomitant anti-inflammatory drugs (corticosteroids) may increase the risk of disease exacerbation in some patients. We found previously that pretreatment of human precision-cut lung slices (PCLS) with SABA impaired subsequent β(2)-agonist-induced bronchodilation, which occurred independently of changes in receptor quantities. Here we provide evidence that prolonged exposure of cultured human airway smooth muscle (HuASM) cells to β(2)-agonists directly augments procontractile signaling pathways elicited by several compounds including thrombin, bradykinin, and histamine. Such treatment did not increase surface receptor amounts or expression of G proteins and downstream effectors (phospholipase Cβ and myosin light chain). In contrast, β-agonists decreased expression of regulator of G protein signaling 5 (RGS5), which is an inhibitor of G-protein-coupled receptor (GPCR) activity. RGS5 knockdown in HuASM increased agonist-evoked intracellular calcium flux and myosin light chain (MLC) phosphorylation, which are prerequisites for contraction. PCLS from Rgs5(-/-) mice contracted more to carbachol than those from WT mice, indicating that RGS5 negatively regulates bronchial smooth muscle contraction. Repetitive β(2)-agonist use may not only lead to reduced bronchoprotection but also to sensitization of excitation-contraction signaling pathways as a result of reduced RGS5 expression.

Interactive effect of cigarette smoke extract and world trade center dust particles on airway cell cytotoxicity

Rescue workers and residents exposed to the environment surrounding the collapse of the World Trade Center (WTC) on September 11, 2001, have suffered a disproportionate incidence of chronic lung disease attributed to the inhalation of airborne dust. To date, the pathophysiology of this lung disease is poorly understood. The aim of this study was to examine whether airborne dust contaminants recovered from the surrounding area 24-48 h after the collapse of the WTC demonstrate direct cytotoxicity to two airway cell types that were most directly exposed to inhaled dust, airway epithelial and smooth muscle cells. It was also of interest to determine whether the presence of these dusts could modulate the effects of cigarette smoke on these cell types in that some of the individuals who responded to the collapse site were also smokers. Human cultured airway epithelial (BEAS-2B) cells were exposed to 10% cigarette smoke extract (CSE), WTC dust particles (10-53 μm; 0.01-0.5 μg/μl), or a combination of the two for 2-24 h. Cell viability was measured by determining mitochondrial integrity (MTT assays) and apoptosis (poly-ADP-ribose polymerase [PARP] immunoblotting). Conditioned cell culture media recovered from the CSE- and/or WTC dust-exposed BEAS-2B cells were then applied to cultured human airway smooth muscle cells that were subsequently assayed for mitochondrial integrity and their ability to synthesize cyclic AMP (a regulator of airway smooth muscle constriction). BEAS-2B cells underwent necrotic cell death following exposure to WTC dust or CSE for 2-24 h without evidence of apoptosis. Smooth muscle cells demonstrated cellular toxicity and enhanced cyclic AMP synthesis following exposure to conditioned media from WTC- or CSE-exposed epithelial cells. These acute toxicity assays of WTC dust and CSE offer insights into lung cell toxicity that may contribute to the pathophysiology of chronic lung disease in workers and residents exposed to WTC dust. These studies clearly showed that WTC dust (at least the supercoarse particle fraction) or CSE alone exerted direct adverse effects on airway epithelial and smooth muscle cells, and altered the signaling properties of airway smooth muscle cells. In addition the combination of CSE and WTC exerted an interactive effect on cell toxicity. It remains to be determined whether these initial cell death events might account, in part, for the chronic lung effects associated with WTC dust exposure among First Responders and others.

Increased synthesis of vascular endothelial growth factor in allergic airway inflammation in histidine decarboxylase knockout (HDC(-/-)) mice

Histamine and vascular endothelial growth factor (VEGF) have been implicated in the pathogenesis of allergic asthma; they enhance inflammation, vascular permeability, and mucus secretion. Histamine was suggested to alter the level of VEGF via the H2 receptors. Here the authors have applied histidine decarboxylase gene-targeted (HDC(-/-)) mice, lacking histamine, to investigate the effect of histamine deficiency on VEGF expression in an animal model of asthma. HDC(-/-) and wild-type (WT) mice were sensitized and challenged with ovalbumin (OVA). VEGF mRNA expression and protein level were determined in the lung. Number of VEGF-positive immune cells of bronchoalveolar lavage (BAL) and their intracellular VEGF content were measured by flow cytometry. VEGF protein level in the lung and in the BAL cells was increased in OVA treated (HDC(-/-)(ova) as well as in WT(ova)) animals compared to their controls. However, there was no difference in the VEGF levels between HDC(-/-) or WT animals, either in the lung or in the BAL cells. In conclusion, increased VEGF production of the lung or BAL immune cells can be induced by allergen provocation independently from the genetic background of the animals. These data suggest that VEGF-mediated allergic processes can persist in the absence of histamine.

Cigarette smoke extracts promote vascular smooth muscle cell proliferation and enhances contractile responses in the vasculature and airway

Cigarette smoke exposure is a strong risk factor for cardiovascular and respiratory diseases. However, the knowledge about how cigarette smoke induces damage to vasculature and airway is limited. The present study was designed to examine the effects of cigarette smoke particles extracted by heptane (heptane-soluble smoke particles, HSP), by water (water-soluble smoke particles, WSP) and by DMSO (DMSO-soluble smoke particles, DSP), which represent lipophilic, hydrophilic and ambiphoteric constituents from the cigarette smoke, respectively. Human aortic smooth muscle cell (HASMC) proliferation was assessed in cell culture. Rat resistance artery and airway contractile responses to serotonin, U46619, phenylephrine, noradrenaline, acetylcholine, des-Arg⁹-bradykinin, bradykinin, sarafotoxin 6c and endothelin-1 were monitored by a sensitive myograph system. Immunocytochemistry and cell-based phosphoELISA assay were used to demonstrate activation of extracellular signal-regulated kinases 1/2 (ERK1/2). For the first time, our results demonstrate that although all the three extracts promote HASMC proliferation, the HSP and DSP effects occur earlier. HSP and DSP, but not WSP, increase the contractile responses to sarafotoxin 6c, U46619 or bradykinin in rat mesenteric artery and/or in bronchi. ERK1/2 is activated by HSP and DSP in HASMCs and inhibition of ERK1/2 abrogated the smoke extracts-induced HASMC proliferation, while blockage of nicotinic receptors had no effects, suggesting that the toxic effects of the smoke extracts occur via activation of intracellular ERK1/2 signalling, but not nicotinic receptors.

Effect of antigenic exposure on airway smooth muscle remodeling in an equine model of chronic asthma

Recent studies suggest that airway smooth muscle remodeling is an early event in asthma, but whether it remains a dynamic process late in the course of the disease is unknown. Moreover, little is known about the effects of an antigenic exposure on chronically established smooth muscle remodeling. We measured the effects of antigenic exposure on airway smooth muscle in the central and peripheral airways of horses with heaves, a naturally occurring airway disease that shares similarities with chronic asthma. Heaves-affected horses (n = 6) and age-matched control horses (n = 5) were kept on pasture before being exposed to indoor antigens for 30 days to induce airway inflammation and bronchoconstriction. Peripheral lung and endobronchial biopsies were collected before and after antigenic exposure by thoracoscopy and bronchoscopy, respectively. Immunohistochemistry and enzymatic labeling were used for morphometric analyses of airway smooth muscle mass and proliferative and apoptotic myocytes. In the peripheral airways, heaves-affected horses had twice as much smooth muscle as control horses. Remodeling was associated with smooth muscle hyperplasia and in situ proliferation, without reduced apoptosis. Further antigenic exposure had no effect on the morphometric data. In central airways, proliferating myocytes were increased compared with control horses only after antigenic exposure. Peripheral airway smooth muscle mass is stable in chronically affected animals subjected to antigenic exposure. This increased mass is maintained in a dynamic equilibrium by an elevated cellular turnover, suggesting that targeting smooth muscle proliferation could be effective at decreasing chronic remodeling.

Expression and function of the inducible costimulator ligand B7-H2 in human airway smooth muscle cells

BACKGROUND

B7-H2 is a ligand for the inducible costimulator (ICOS). The aim of this study was to examine the expression and function of B7-H2 in human airway smooth muscle (ASM) cells and compare them with those of CD40 or OX40 ligand (OX40L).

METHODS

Expression of B7-H2, CD40 and OX40L in ASM cells and their respective counterparts in T cells was analyzed by RT-PCR or flow cytometry. The modulating effect of polyinosinic-polycytidylic acid (poly I:C) on expression of B7-H2, CD40 and OX40L was also examined. The function of these three molecules was evaluated by virtue of adhesion of anti-CD3-activated T cells, IL-6 and IL-8 production and DNA synthesis.

RESULTS

ASM cells constitutively expressed B7-H2, CD40 and OX40L that mediated adhesion of activated T cells expressing ICOS, CD40L and OX40. ASM cells responded to poly I:C with upregulated expression of B7-H2, CD40 and OX40L and displayed enhanced adhesion of activated T cells. Functional analysis performed on untreated ASM cells showed that engagement of B7-H2 with ICOS-Ig clearly induced DNA synthesis, whereas that of CD40 or OX40L with trimeric CD40L or OX40-Ig greatly increased IL-6 and IL-8 production. These responses were enhanced in poly I:C-treated ASM cells.

CONCLUSIONS

The data demonstrate that ASM cells express functionally active B7-H2, CD40 and OX40L and suggest that B7-H2-dependent signaling may play an active role in a proliferative response rather than in cytokine and chemokine production. In addition, the modulation of B7-H2, CD40 and OX40L expression and function by poly I:C may have important implications for the function of virus-infected ASM cells.

Modulation of epidermal growth factor receptor binding to human airway smooth muscle cells by glucocorticoids and beta2-adrenergic receptor agonists

EGF receptors (EGFRs) are increased in airway smooth muscle in asthma, which may contribute to both their hyperproliferation and hypercontractility. Lysophosphatidic acid (LPA) is a candidate pathological agent in asthma and other airway diseases, and LPA upregulates EGFRs in human airway smooth muscle (HASM) cells. We tested whether therapeutic glucocorticoids and/or beta(2)-adrenergic receptor (beta(2)AR) agonists also alter EGFR binding in HASM cells. Exposure to glucocorticoids for 24 h induced a twofold increase in EGFR binding similar to that with LPA; fluticasone was markedly more potent than dexamethasone. The increase in EGFR binding by glucocorticoids required 24-h exposure, consistent with transcription-mediated effects. Although the increase in EGFR binding was blocked by the protein synthesis inhibitor cycloheximide for LPA, fluticasone, and dexamethasone, only LPA induced a significant increase in EGFR protein expression detected by immunoblotting. In contrast to the increased binding induced by the glucocorticoids, the beta(2)AR agonists isoproterenol, albuterol, and salmeterol all induced a decrease in EGFR binding. beta(2)AR agonist effects were multiphasic, with an initial decline at 2-4 h that reversed by 6 h and a second, somewhat greater decrease by 18-24 h. In cells pretreated with glucocorticoids, the decreases in EGFR binding by subsequent beta(2)AR treatment were not statistically significant; glucocorticoid upregulation of EGFRs also prevented further increases by LPA. Similar increases by glucocorticoids and decreases by beta(2)AR agonists were found in HFL-1 human lung fibroblasts. These complex and opposing effects of clinically relevant glucocorticoids and beta(2)AR agonists on airway mesenchymal cell EGFRs likely contribute to their overall therapeutic profile in the diseased airway.

Galpha13 regulates methacholine-induced contraction of bronchial smooth muscle via phosphorylation of MLC20

Reversible airway constriction is induced by an increase in airway smooth muscle contractility in response to methacholine likely as a bronchospastic stimulus. Despite the finding of Galpha12 and Galpha13 up-regulation in airway hyperresponsive animals, their functional role of contraction in airway smooth muscle has not been directly explored. This study investigated the differential regulatory role of Galpha12/Galpha13 in methacholine-induced contraction of trachea and bronchus in Galpha12 or Galpha13 gene knockout mice after ovalbumin sensitization and challenges. Organ bath assays and videomicroscopy revealed that Galpha13 deficiency delayed methacholine-induced contractile response of bronchiolar smooth muscle, but not that of tracheal smooth muscle. In primary bronchial smooth muscle cells, knockdown of Galpha13 blocked methacholine-induced phosphorylation of 20 kDa regulatory light chain of myosin II (MLC20), a prerequisite step for the contractile initiation of actin and myosin. Galpha13-dependent MLC20 phosphorylation was confirmed in murine embryonic fibroblasts. After ovalbumin sensitization and challenges, wild type mice exhibited methacholine-induced bronchial contraction of lung tissue. Heterozygous absence of the Galpha13 gene abrogated methacholine-induced contractions, whereas homozygous absence of the Galpha12 gene failed to do so. Our findings indicate that Galpha13, but not Galpha12, specifically regulates cholinergic bronchial contraction in airway responsiveness via controlling phosphorylation of MLC20 by methacholine.

Targeting human mast cells expressing g-protein-coupled receptors in allergic diseases

The G-protein-coupled receptors (GPCRs) are the largest known group of integral membrane receptor proteins and are the most common targets of pharmacotherapy. Mast cells (MCs) have been reported to play an important role in allergic diseases, such as urticaria and bronchial asthma. There is an increasing body of clinical evidence that MCs are recruited into allergic reactions by non-IgE-dependent mechanisms. Human MCs are activated and secrete histamine in response to neuropeptides, such as substance P and somatostatin, mediated by a GPCR, MRGX2. The microenvironment surrounding MCs in their resident tissues is likely to contain multiple factors that modify antigen-dependent MC activation. MCs express various GPCRs, and since the function of human MCs is modulated by various GPCR ligands, such as adenosine and sphingosine-1-phosphate, which are present in high levels in the bronchial alveolar lavage fluid of asthmatic patients, the GPCRs expressed on MCs may play an important role in human allergic diseases. The GPCRs expressed on MCs may serve as drug targets for the treatment of allergic diseases.

Tissue-engineered endothelial and epithelial implants differentially and synergistically regulate airway repair

The trilaminate vascular architecture provides biochemical regulation and mechanical integrity. Yet regulatory control can be regained after injury without recapitulating tertiary structure. Tissue-engineered (TE) endothelium controls repair even when placed in the perivascular space of injured vessels. It remains unclear from vascular repair studies whether endothelial implants recapitulate the vascular epithelial lining or expose injured tissues to endothelial cells (ECs) with unique healing potential because ECs line the vascular epithelium and the vasa vasorum. We examined this issue in a nonvascular tubular system, asking whether airway repair is controlled by bronchial epithelial cells (EPs) or by ECs of the perfusing bronchial vasculature. Localized bronchial denuding injury damaged epithelium, narrowed bronchial lumen, and led to mesenchymal cell hyperplasia, hypervascularity, and inflammatory cell infiltration. Peribronchial TE constructs embedded with EPs or ECs limited airway injury, although optimum repair was obtained when both cells were present in TE matrices. EC and EP expression of PGE(2), TGFbeta1, TGFbeta2, GM-CSF, IL-8, MCP-1, and soluble VCAM-1 and ICAM-1 was altered by matrix embedding, but expression was altered most significantly when both cells were present simultaneously. EPs may provide for functional control of organ injury and fibrous response, and ECs may provide for preservation of tissue perfusion and the epithelium in particular. Together the two cells optimize functional restoration and healing, suggesting that multiple cells of a tissue contribute to the differentiated biochemical function and repair of a tissue, but need not assume a fixed, ordered architectural relationship, as in intact tissues, to achieve these effects.