Airway remodeling in asthma: new mechanisms and potential for pharmacological intervention

Aging, brain-derived neurotrophic factor, and allergen-induced pulmonary responses in mice

Asthma in the elderly is being recognized as more severe, resistant to standard therapies, and having greater morbidity. Therefore, it becomes important to understand the impact of aging-associated airway structure and functional changes toward pathogenesis of asthma in the elderly. Here, airway smooth muscle plays important roles in airway hyperreactivity and structural remodeling. The role of smooth muscle in asthma can be modulated by growth factors [including neurotrophins such as brain-derived neurotrophic factor (BDNF)] and proinflammatory senescence factors. In this study, we investigated aging effects on airway hyperreactivity, structural remodeling, inflammation, and senescence in a mouse model of allergic asthma. C57BL/6J wild-type mice or smooth muscle-specific BDNF knockout mice at 4, 18, and 24 mo of age were intranasally exposed to mixed allergens (MAs, ovalbumin, Aspergillus, Alternaria, and house dust mite) over 4 wk. Assessing lung function by flexiVent, we found that compared with 4-mo-old mice, 18- and 24-mo-old C57BL/6J mice showed decreased airway resistance and increased airway compliance after PBS or MA treatment. Deletion of smooth muscle BDNF blunted airway hyperreactivity in aged mice. Lung histology analysis revealed that aging increased bronchial airway thickness and decreased lung inflammation. Multiplex assays showed that aging largely reduced allergen-induced lung expression of proinflammatory chemokines and cytokines. By immunohistochemistry staining, we found that aging increased bronchial airway expression of senescence markers, including p21, phospho-p53, and phospho-γH2A.X. Our data suggest that aging-associated increase of airway senescence in the context of allergen exposure may contribute to asthma pathology in the elderly.NEW & NOTEWORTHY The pathogenesis of asthma in elderly is not well understood. Using a mouse model of asthma, we show that aging results in decreased lung function and less responsiveness to allergen exposure, impacted by locally produced brain-derived neurotrophic factor. Aging also decreases allergen-induced inflammation but increases airway remodeling and senescence. Our results suggest that senescence pathways may contribute to asthma pathogenesis in elderly.

TSLP Induces Epithelial-Mesenchymal Transition in Nasal Epithelial Cells From Allergic Rhinitis Patients Through TGF-β1/Smad2/3 Signaling

BACKGROUND

Airway remodeling is demonstrated in Asian patients with allergic rhinitis (AR). The epithelial-mesenchymal transition (EMT) is one of the key mechanisms underlying airway remodeling. Thymic stromal lymphopoietin (TSLP) is an important contributor to airway remodeling. Although increased TSLP is found in AR, little is known about whether TSLP is involved in airway remodeling through induction of the EMT.

OBJECTIVE

We investigated the effect of TSLP on the EMT in human nasal epithelial cells (HNECs) from AR patients.

METHODS

Human nasal epithelial cells from AR patients were stimulated with TSLP in the absence or presence of the preincubation with a selective inhibitor of transforming growth factor beta 1 (TGF-β1) receptor (SB431542). The expression of TGF-β1 in the cells was evaluated by using real-time polymerase chain reaction, Western blotting, and immunocytochemistry. Western blotting and immunocytochemistry were used to assay EMT markers including vimentin, fibroblast-specific protein 1 (FSP1) and E-cadherin, small mothers against decapentaplegic homolog2/3 (Smad2/3), and phosphorylated Smad2/3 in the cells. The levels of extracellular matrix components such as collagens I and III in supernatants were measured by enzyme-linked immunoassay. Morphological changes of the cells were observed under inverted phase-contrast microscope.

RESULTS

A concentration-dependent increase of TGF-β1 mRNA and protein was observed following stimulation with TSLP. Furthermore, TSLP decreased the expression of E-cadherin protein, but upregulated the production of FSP1 and vimentin proteins along with increased levels of collagens I and III, and the morphology of the cells was transformed into fibroblast-like shape. Additionally, a significant increase was found in phosphorylation of Smad2/3 protein. However, these effects were reversed by SB431542 preincubation.

CONCLUSION

TSLP-induced HNECs to undergo the EMT process via TGF-β1-mediated Smad2/3 activation. TSLP is an activator of the EMT in HNECs and might be a potential target for inhibiting EMT and reducing airway remodeling in AR.

Semaphorin 7a aggravates TGF-β1-induced airway EMT through the FAK/ERK1/2 signaling pathway in asthma

Background

TGF-β1 can induce epithelial-mesenchymal transition (EMT) in primary airway epithelial cells (AECs). Semaphorin7A (Sema7a) plays a crucial role in regulating immune responses and initiating and maintaining transforming growth factor β1 TGF-β1-induced fibrosis.

Objective

To determine the expression of Sema7a, in serum isolated from asthmatics and non-asthmatics, the role of Sema7a in TGF-β1 induced proliferation, migration and airway EMT in human bronchial epithelial cells (HBECs) in vitro.

Methods

The concentrations of Sema7a in serum of asthmatic patients was detected by enzyme-linked immunosorbent assay (ELISA). The expressions of Sema7a and integrin-β1 were examined using conventional western blotting and real-time quantitative PCR (RT-PCR). Interaction between the Sema7a and Integrin-β1 was detected using the Integrin-β1 blocking antibody (GLPG0187). The changes in EMT indicators were performed by western blotting and immunofluorescence, as well as the expression levels of phosphorylated Focal-adhesion kinase (FAK) and Extracellular-signal-regulated kinase1/2 (ERK1/2) were analyzed by western blot and their mRNA expression was determined by RT-PCR.

Results

We described the first differentially expressed protein of sema7a, in patients with diagnosed bronchial asthma were significantly higher than those of healthy persons (P<0.05). Western blotting and RT-PCR showed that Sema7a and Integrin-β1 expression were significantly increased in lung tissue from the ovalbumin (OVA)-induced asthma model. GLPG0187 inhibited TGF-β1-mediated HBECs EMT, proliferation and migration, which was associated with Focal-adhesion kinase (FAK) and Extracellular-signal-regulated kinase1/2 (ERK1/2) phosphorylation.

Conclusion

Sema7a may play an important role in asthma airway remodeling by inducing EMT. Therefore, new therapeutic approaches for the treatment of chronic asthma, could be aided by the development of agents that target the Sema7a.

Bronchial epithelial and airway smooth muscle cell interactions in health and disease

Chronic pulmonary diseases such as asthma, COPD, and Idiopathic pulmonary fibrosis are significant causes of mortality and morbidity worldwide. Currently, there is no radical treatment for many chronic pulmonary diseases, and the treatment options focus on relieving the symptoms and improving lung function. Therefore, efficient therapeutic agents are highly needed. Bronchial epithelial cells and airway smooth muscle cells and their crosstalk play a significant role in the pathogenesis of these diseases. Thus, targeting the interactions of these two cell types could open the door to a new generation of effective therapeutic options. However, the studies on how these two cell types interact and how their crosstalk adds up to respiratory diseases are not well established. With the rise of modern research tools and technology, such as lab-on-a-chip, organoids, co-culture techniques, and advanced immunofluorescence imaging, a substantial degree of evidence about these cell interactions emerged. Hence, this contribution aims to summarize the growing evidence of bronchial epithelial cells and airway smooth muscle cells crosstalk under normal and pathophysiological conditions. The review first discusses the impact of airway smooth muscle cells on the epithelium in inflammatory settings. Later, it examines the role of airway smooth muscle cells in the early development of bronchial epithelial cells and their recovery after injury. Then, it deliberates the effects of both healthy and stressed epithelial cells on airway smooth muscle cells, taking into account three themes; contraction, migration, and proliferation.

Long noncoding RNA antisense noncoding RNA in the INK4 locus inhibition alleviates airway remodeling in asthma through the regulation of the microRNA-7-5p/early growth response factor 3 axis

Asthma, a chronic inflammatory disease of the airways, clinically manifests as airway remodeling. The purpose of this study was to probe the potential role of long noncoding RNA (lncRNA) antisense noncoding RNA in the INK4 locus (lncRNA ANRIL) in the proliferation and migration of airway smooth muscle cell (ASMC) and to explore its potential mechanisms in asthma. Serum samples were obtained from 30 healthy volunteers and 30 patients with asthma. Additionally, platelet-derived growth factor-BB (PDGF-BB) was used to induce airway remodeling in ASMCs. The level of lncRNA ANRIL and microRNA (miR)-7-5p in serum samples were measured by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). TargetScan predicted the binding site of miR-7-5p to early growth response factor 3 (EGR3) and validated the results using a dual-luciferase reporter assay. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) and Transwell assays were used to detect cellular proliferation and migration, respectively. Subsequently, changes in proliferation- and migration-related genes were verified using western blot analysis and qRT-PCR. These results indicate that lncRNA ANRIL was upregulated in the serum and PDGF-BB-induced ASMCs of patients with asthma, whereas miR-7-5p expression was reduced. EGR3 was a direct target of miR-7-5p. LncRNA ANRIL silencing inhibited the proliferation or migration of ASMCs induced by PDGF-BB through miR-7-5p upregulation. Mechanistic studies indicated that miR-7-5p inhibits the proliferation or migration of PDGF-BB-induced ASMCs by decreasing EGR3 expression. EGR3 upregulation reverses the role of miR-7-5p in airway remodeling. Thus, downregulation of lncRNA ANRIL inhibits airway remodeling through inhibiting the proliferation and migration of PDGF-BB-induced ASMCs by regulating miR-7-5p/EGR3 signaling.

Bronchial Remodeling-based Latent Class Analysis Predicts Exacerbations in Severe Preschool Wheezers

Rationale: Children with preschool wheezing represent a very heterogeneous population with wide variability regarding their clinical, inflammatory, obstructive, and/or remodeling patterns. We hypothesized that assessing bronchial remodeling would help clinicians to better characterize severe preschool wheezers. Objectives: The main objective was to identify bronchial remodeling-based latent classes of severe preschool wheezers. Secondary objectives were to compare cross-sectional and longitudinal clinical and biological data between classes and to assess the safety of bronchoscopy. Methods: This double-center prospective study (NCT02806466) included severe preschool wheezers (1-5 yr old) requiring fiberoptic bronchoscopy. Bronchial remodeling parameters (i.e., epithelial integrity, reticular basement membrane [RBM] thickness, mucus gland, fibrosis and bronchial smooth muscle [BSM] areas, the density of blood vessels, and RBM-BSM distance) were assessed and evaluated by latent class analysis. An independent cohort of severe preschool wheezers (NCT04558671) was used to validate our results. Measurements and Main Results: Fiberoptic bronchoscopy procedures were well tolerated. A two-class model was identified: Class BR1 was characterized by increased RBM thickness, normalized BSM area, the density of blood vessels, decreased mucus gland area, fibrosis, and RBM-BSM distance compared with Class BR2. No significant differences were found between classes in the year before fiberoptic bronchoscopy. By contrast, Class BR1 was associated with a shorter time to first exacerbation and an increased risk of both frequent (3 or more) and severe exacerbations during the year after bronchoscopy in the two cohorts. Conclusions: Assessing bronchial remodeling identified severe preschool wheezers at risk of frequent and severe subsequent exacerbations with a favorable benefit to risk ratio.

Vitamin D ameliorates asthma-induced lung injury by regulating HIF-1α/Notch1 signaling during autophagy

Herein, we aimed to determine the effect of vitamin D (Vit D) and underlying mechanisms on asthma-induced lung injury via regulation of HIF-1α/Notch1 (hypoxia-inducible factor 1 alpha/neurogenic locus notch homolog protein 1) signaling during autophagy. We established an asthma mouse model using respiratory syncytial virus (RSV) nasal drop combined with ovalbumin (OVA) atomization. Mice were treated with different Vit D concentrations. Pathological changes and cell apoptosis were examined using hematoxylin-eosin (HE) staining and TUNEL (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP) nick end-labeling) assay, respectively. Additionally, periodic acid-Schiff (PAS) and Masson's trichrome staining solutions were used to examine changes in lung tissue. Immunofluorescence determined LC 3B (microtubule-associated protein 1 light chain 3B) expression in lung tissues, whereas western blotting and immunohistochemistry were used to evaluate other proteins, including HIF-1α and Notch1. Compared with the normal group, the asthma model group exhibited pathological lung tissue deterioration, elevated fibrosis, increased apoptosis cell numbers, and upregulated autophagy. Vitamin D supplementation ameliorated pathological changes and fibrosis in the lung tissue. Furthermore, Vit D treatment significantly suppressed apoptotic cell numbers and autophagy while enhancing the HIF-1α/Notch1 pathway. Given the HIF-1α/Notch1 agonistic activity, Vit D treatment inhibited apoptosis cell numbers, which were increased following asthma-induced upregulation of autophagy. Vitamin D improved asthma-induced lung tissue injury by suppressing autophagy via regulation of HIF-1α/Notch1 signaling in vivo.

MiR-365-3p is a negative regulator in IL-17-mediated asthmatic inflammation

Background

Interleukin-17, the major proinflammatory cytokine secreted by Th17 cells, makes essential contribution to pathogenesis of severe asthma, while the detailed mechanisms, especially the involvement of microRNAs which are also important participants in asthma progression, remains largely unclear.

Methods

In this study, we established a house dust mite (HDM) extract-induced murine asthmatic models and the miRNA expression in the lung tissues of mice were profiled by miRNA microarray assay. The effect of miR-365-3p on IL-17-mediated inflammation was examined by qRT-PCR and immunoblotting analysis. The involvement of ARRB2 as target gene of miR-365-3p was verified by overexpression or RNA interference.

Results

HDM extract-induced asthmatic inflammation was proved to be IL17-mediated and miR-365-3p was screened out to be the only miRNA exclusively responsive to IL-17. miR-365-3p, whose expression was significantly downregulated upon IL-17 stimulation, was demonstrated to exert remarkable anti-inflammatory effect to decrease IL-17-provoked inflammatory cytokines (KC/IL-8 and IL-6) in both airway epithelial cells and macrophages of murine and human origins, verifying its universal antagonizing activity against IL-17-initiated inflammation across the two species. ARRB2 was characterized as the key target of miR-365-3p to negate IL-17-induced inflammatory cytokines.

Conclusion

Taken together, our data supported the notion that miR-365-3p, which was diminished by IL-17 in murine and human asthmatic pathogenesis, functioned as an essential negative mediator in IL-17-stimuated inflammatory response by targeting ARRB2, which would shed new light to the understanding and therapeutics thereof of asthmatic inflammation.

Discovery of a Highly Selective β2-Adrenoceptor Agonist with a 2-Amino-2-phenylethanol Scaffold as an Oral Antiasthmatic Agent

Asthma patients in resource-poor countries cannot obtain adequate basic asthma medications because most asthma medications are supplied as inhalants. An alternative approach is to create oral antiasthmatic drugs with high β₂/β₁-selectivity, which should reduce treatment costs. In this study, we designed a cohort of compounds 1 using 2-(4-amino-3-chloro-5-(trifluoromethyl)phenyl)-2-(tert-butylamino)ethan-1-ol hydrogen chloride (1a) as the lead compound with an aim to expand the library of compounds possessing the 2-amino-2-phenylethanol scaffold. Structure-activity relationship studies on these compounds revealed that compounds created showed remarkable β₂ selectivity compared to isoproterenol and gave additional insights on the rational design of β₂-adrenoceptor agonists. Moreover, 1a was found as the best candidate compound showing the greatest potential for drug development. Cell-based assays showed that 1a was about 10 times more selective than salbutamol toward the β₂-adrenoceptor. Moreover, 1a exhibited good oral bioavailability and low acute oral toxicity. These data reveal 1a as an oral antiasthmatic agent.

Role of Th17 Cytokines in Airway Remodeling in Asthma and Therapy Perspectives

Airway remodeling is a frequent pathological feature of severe asthma leading to permanent airway obstruction in up to 50% of cases and to respiratory disability. Although structural changes related to airway remodeling are well-characterized, immunological processes triggering and maintaining this phenomenon are still poorly understood. As a consequence, no biotherapy targeting cytokines are currently efficient to treat airway remodeling and only bronchial thermoplasty may have an effect on bronchial nerves and smooth muscles with uncertain clinical relevance. Th17 cytokines, including interleukin (IL)-17 and IL-22, play a role in neutrophilic inflammation in severe asthma and may be involved in airway remodeling. Indeed, IL-17 is increased in sputum from severe asthmatic patients, induces the expression of "profibrotic" cytokines by epithelial, endothelial cells and fibroblasts, and provokes human airway smooth muscle cell migration in in vitro studies. IL-22 is also increased in asthmatic samples, promotes myofibroblast differentiation, epithelial-mesenchymal transition and proliferation and migration of smooth muscle cells in vitro. Accordingly, we also found high levels of IL-17 and IL-22 in a mouse model of dog-allergen induced asthma characterized by a strong airway remodeling. Clinical trials found no effect of therapy targeting IL-17 in an unselected population of asthmatic patients but showed a potential benefit in a sub-population of patients exhibiting a high level of airway reversibility, suggesting a potential role on airway remodeling. Anti-IL-22 therapies have not been evaluated in asthma yet but were demonstrated efficient in severe atopic dermatitis including an effect on skin remodeling. In this review, we will address the role of Th17 cytokines in airway remodeling through data from in vitro, in vivo and translational studies, and examine the potential place of Th17-targeting therapies in the treatment of asthma with airway remodeling.

Effects of cigarette smoke on the aggravation of ovalbumin-induced asthma and the expressions of TRPA1 and tight junctions in mice

The occurrence of asthma is closely related to environmental factors such as cigarette smoke (CS), one of the common risk factors. Environmental stimuli have the potential to activate transient receptor potential ankyrin 1 (TRPA1) and cause or aggravate asthma. The destruction of tight junctions (TJs) between airway epithelial cells by environmental stimuli in asthma has been researched. It is worth exploring whether CS can injury TJs and aggravate asthma by activating TRPA1. The objective of this study was to investigate the aggravation of CS on ovalbumin (OVA)-induced asthma related phenotypes and TJs expression in mice, and to explore the relationship between TRPA1 and the expression of TJs protein. Female wild type (WT) C57BL/6 mice, induced by OVA, CS and OVA plus CS (OVA + CS) respectively, were used to establish a 42-day asthma model, and mice with TRPA1 knockout (TRPA1-/-) were treated in the same way. This study detected the number of inflammatory cells in peripheral blood and bronchoalveolar lavage fluid (BALF), the levels of IL-4, IL-5, IL-13 in BALF, enhanced pause (Penh) of lung function, pathological changes and the gene and protein expressions of TRPA1 and TJs (including ZO-1, Occludin and Claudin-2) in lung tissues. Compared with normal saline (NS) group, WT mice in the OVA group and OVA + CS group were significantly higher in asthma related phenotypes. The WT-OVA + CS group also showed higher Penh value, levels of IL-5 and IL-13 in BALF and lung tissue injury scores when compared with the WT-OVA group and WT-CS group. However, WT-OVA + CS group mice had significantly larger number of neutrophils in BALF than the WT-OVA group, and had larger number of eosinophils in peripheral blood and higher levels of IL-4 in BALF than the WT-CS group. Meanwhile, compared with the WT-NS group, the expressions of TRPA1 and Claudin-2 in lung tissues increased in other three groups while their expressions of ZO-1 and Occludin decreased, among which, the WT-OVA + CS group showed more remarkable changes. Compared with the WT-OVA + CS group, mice in the TRPA1-/--OVA + CS showed a significant decrease in the number of inflammatory cells, levels of IL-4, IL-5 and IL-13 in BALF, Penh value and lung tissue injury score, and a downregulation of Claudin-2 expression while an upregulation of ZO-1 and Occludin expressions. In addition, the airway inflammation and injury, and the expressions of ZO-1, Occluding and Claudin-2 expressions were found with no statistic differences between TRPA1-/--OVA group and TRPA1-/--OVA + CS group. These results suggest that CS has aggravated the airway inflammation, pathological damage and destruction of TJs in airway epithelium of OVA-induced asthmatic mice, the processes of which are related to the increase of TRPA1 expression.

Crucial role of fatty acid oxidation in asthmatic bronchial smooth muscle remodelling

BACKGROUND

Bronchial smooth muscle (BSM) remodelling in asthma is related to an increased mitochondrial biogenesis and enhanced BSM cell proliferation in asthma. Since (i) mitochondria produce the highest levels of cellular energy and (ii) fatty acid beta-oxidation is the most powerful way to produce ATP, we hypothesized that, in asthmatic BSM cells, energetic metabolism is shifted towards the beta-oxidation of fatty acids.

OBJECTIVES

We aimed to characterize BSM cell metabolism in asthma both in vitro and ex vivo to identify a novel target for reducing BSM cell proliferation.

METHODS

Twenty-one asthmatic and 31 non-asthmatic patients were enrolled. We used metabolomic and proteomic approaches to study BSM cells. Oxidative stress, ATP synthesis, fatty acid endocytosis, metabolite production, metabolic capabilities, mitochondrial networks, cell proliferation and apoptosis were assessed on BSM cells. Fatty acid content was assessed in vivo using MALDI-spectrometry imaging.

RESULTS

Asthmatic BSM cells were characterized by an increased rate of mitochondrial respiration with a stimulated ATP production and mitochondrial β-oxidation. Fatty acid consumption was increased in asthmatic BSM both in vitro and ex vivo. Proteome remodelling of asthmatic BSM occurred via 2 canonical mitochondrial pathways. The levels of CPT2 and LDL-receptor, which internalize fatty acids through mitochondrial and cell membranes, respectively, were both increased in asthmatic BSM cells. Blocking CPT2 or LDL-receptor drastically and specifically reduced asthmatic BSM cell proliferation.

CONCLUSION

This study demonstrates a metabolic switch towards mitochondrial beta-oxidation in asthmatic BSM and identifies fatty acid metabolism as a new key target to reduce BSM remodelling in asthma.

Mitochondria are involved in bronchial smooth muscle remodeling in severe preschool wheezers

BACKGROUND

Bronchial remodeling is a key feature of asthma that is already present in preschoolers with wheezing. Moreover, bronchial smooth muscle (BSM) remodeling at preschool age is predictive of asthma at school age. However, the mechanism responsible for BSM remodeling in preschoolers with wheezing remains totally unknown. In contrast, in adult asthma, BSM remodeling has been associated with an increase in BSM cell proliferation related to increased mitochondrial mass and biogenesis triggered by an altered calcium homeostasis. Indeed, BSM cell proliferation was decreased in vitro by the calcium channel blocker gallopamil.

OBJECTIVE

Our aim was to investigate the mechanisms involved in BSM cell proliferation in preschoolers with severe wheezing, with special attention to the role of mitochondria and calcium signaling.

METHODS

Bronchial tissue samples obtained from 12 preschool controls without wheezing and 10 preschoolers with severe wheezing were used to measure BSM mass and establish primary BSM cell cultures. BSM cell proliferation was assessed by manual counting and flow cytometry, ATP content was assessed by bioluminescence, mitochondrial respiration was assessed by using either the Seahorse or Oroboros technique, mitochondrial mass and biogenesis were assessed by immunoblotting, and calcium response to carbachol was assessed by confocal microscopy. The effect of gallopamil was also evaluated.

RESULTS

BSM mass, cell proliferation, ATP content, mitochondrial respiration, mass and biogenesis, and calcium response were all increased in preschoolers with severe wheezing compared with in the controls. Gallopamil significantly decreased BSM mitochondrial biogenesis and mass, as well as cell proliferation.

CONCLUSION

Mitochondria are key players in BSM cell proliferation in preschoolers with severe wheezing and could represent a potential target to treat BSM remodeling at an early stage of the disease.

Role of Airway Smooth Muscle in Inflammation Related to Asthma and COPD

Airway smooth muscle contributes to both contractility and inflammation in the pathophysiology of asthma and COPD. Airway smooth muscle cells can change the degree of a variety of functions, including contraction, proliferation, migration, and the secretion of inflammatory mediators (phenotype plasticity). Airflow limitation, airway hyperresponsiveness, β₂-adrenergic desensitization, and airway remodeling, which are fundamental characteristic features of these diseases, are caused by phenotype changes in airway smooth muscle cells. Alterations between contractile and hyper-contractile, synthetic/proliferative phenotypes result from Ca²⁺ dynamics and Ca²⁺ sensitization. Modulation of Ca²⁺ dynamics through the large-conductance Ca²⁺-activated K⁺ channel/L-type voltage-dependent Ca²⁺ channel linkage and of Ca²⁺ sensitization through the RhoA/Rho-kinase pathway contributes not only to alterations in the contractile phenotype involved in airflow limitation, airway hyperresponsiveness, and β₂-adrenergic desensitization but also to alteration of the synthetic/proliferative phenotype involved in airway remodeling. These Ca²⁺ signal pathways are also associated with synergistic effects due to allosteric modulation between β₂-adrenergic agonists and muscarinic antagonists. Therefore, airway smooth muscle may be a target tissue in the therapy for these diseases. Moreover, the phenotype changing in airway smooth muscle cells with focuses on Ca²⁺ signaling may provide novel strategies for research and development of effective remedies against both bronchoconstriction and inflammation.

TNFα induces mitochondrial fragmentation and biogenesis in human airway smooth muscle

In human airway smooth muscle (hASM), mitochondrial volume density is greater in asthmatic patients compared with normal controls. There is also an increase in mitochondrial fragmentation in hASM of moderate asthmatics associated with an increase in dynamin-related protein 1 (Drp1) and a decrease in mitofusin 2 (Mfn2) expression, mitochondrial fission, and fusion proteins, respectively. Proinflammatory cytokines such TNFα contribute to hASM hyperreactivity and cell proliferation associated with asthma. However, the involvement of proinflammatory cytokines in mitochondrial remodeling is not clearly established. In nonasthmatic hASM cells, mitochondria were labeled using MitoTracker Red and imaged in three dimensions using a confocal microscope. After 24-h TNFα exposure, mitochondria in hASM cells were more fragmented, evidenced by decreased form factor and aspect ratio and increased sphericity. Associated with increased mitochondrial fragmentation, Drp1 expression increased while Mfn2 expression was reduced. TNFα also increased mitochondrial biogenesis in hASM cells reflected by increased peroxisome proliferator-activated receptor-γ coactivator 1α expression and increased mitochondrial DNA copy number. Associated with mitochondrial biogenesis, TNFα exposure also increased mitochondrial volume density and porin expression, resulting in an increase in maximum O2 consumption rate. However, when normalized for mitochondrial volume density, O2 consumption rate per mitochondrion was reduced by TNFα exposure. Associated with mitochondrial fragmentation and biogenesis, TNFα also increased hASM cell proliferation, an effect mimicked by siRNA knockdown of Mfn2 expression and mitigated by Mfn2 overexpression. The results of this study support our hypothesis that in hASM cells exposed to TNFα mitochondria are more fragmented, with an increase in mitochondrial biogenesis and mitochondrial volume density resulting in reduced O2 consumption rate per mitochondrion.

Specific Ag-guiding nano-vaccines attenuate neutrophil-dominant allergic asthma

Polymorphonuclear neutrophils (PMN) are one fraction of the major inflammatory cells in allergic asthma (asthma, in short); the role of PMN in the asthma pathogenesis is not fully understood yet. This study aims to investigate the effects of specific Ag-guiding exosomes on suppressing the neutrophil-dominant airway inflammation. In this study, BALB/c mice were immunized with ovalbumin plus complete Freund adjuvant to induce an asthma model featured with neutrophil-dominant lung inflammation. The Ag specific PMN (sPMN)-targeting exosomes (tExo), that were exosomes carrying a complex of specific Ag/anti-CD64 Ab and Fas ligand, were constructed to be used to alleviate neutrophilic asthma in mice. We found that sPMNs were the major cellular component in bronchoalveolar lavage fluid (BALF) in asthma mice, while less than 3% PMNs in naive control mice. The sPMNs expressed higher levels of CD64, which formed complexes with Ag-specific IgG (sIgG). The sIgG/CD64 complex-carrying PMNs could be activated upon exposing to specific Ags. Exposure to tExos induced Ag-specific PMNs apoptosis. Administration of tExos efficiently suppressed experimental asthma. We conclude that a fraction of sPMN was identified in the airway of asthma mice. The sPMNs could be activated upon exposure to specific Ags. tExos could induce sPMNs apoptosis, that show the translational potential in the treatment of asthma.

Inflammation-Induced Protein Unfolding in Airway Smooth Muscle Triggers a Homeostatic Response in Mitochondria

The effects of airway inflammation on airway smooth muscle (ASM) are mediated by pro-inflammatory cytokines such as tumor necrosis factor alpha (TNFα). In this review article, we will provide a unifying hypothesis for a homeostatic response to airway inflammation that mitigates oxidative stress and thereby provides resilience to ASM. Previous studies have shown that acute exposure to TNFα increases ASM force generation in response to muscarinic stimulation (hyper-reactivity) resulting in increased ATP consumption and increased tension cost. To meet this increased energetic demand, mitochondrial O₂ consumption and oxidative phosphorylation increases but at the cost of increased reactive oxygen species (ROS) production (oxidative stress). TNFα-induced oxidative stress results in the accumulation of unfolded proteins in the endoplasmic reticulum (ER) and mitochondria of ASM. In the ER, TNFα selectively phosphorylates inositol-requiring enzyme 1 alpha (pIRE1α) triggering downstream splicing of the transcription factor X-box binding protein 1 (XBP1s); thus, activating the pIRE1α/XBP1s ER stress pathway. Protein unfolding in mitochondria also triggers an unfolded protein response (^mtUPR). In our conceptual framework, we hypothesize that activation of these pathways is homeostatically directed towards mitochondrial remodeling via an increase in peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PGC1α) expression, which in turn triggers: (1) mitochondrial fragmentation (increased dynamin-related protein-1 (Drp1) and reduced mitofusin-2 (Mfn2) expression) and mitophagy (activation of the Phosphatase and tensin homolog (PTEN)-induced putative kinase 1 (PINK1)/Parkin mitophagy pathway) to improve mitochondrial quality; (2) reduced Mfn2 also results in a disruption of mitochondrial tethering to the ER and reduced mitochondrial Ca²⁺ influx; and (3) mitochondrial biogenesis and increased mitochondrial volume density. The homeostatic remodeling of mitochondria results in more efficient O₂ consumption and oxidative phosphorylation and reduced ROS formation by individual mitochondrion, while still meeting the increased ATP demand. Thus, the energetic load of hyper-reactivity is shared across the mitochondrial pool within ASM cells.

Multiple organs involved in the pathogenesis of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) represents the leading cause of chronic liver disease worldwide and the anticipated health burden is huge. There are limited therapeutic approaches for NAFLD now. It’s imperative to get a better understanding of the disease pathogenesis if new treatments are to be discovered. As the hepatic manifestation of metabolic syndrome, this disease involves complex interactions between different organs and regulatory pathways. It’s increasingly clear that brain, gut and adipose tissue all contribute to NAFLD pathogenesis and development, in view of their roles in energy homeostasis. In the present review, we try to summarize currently available data regarding NAFLD pathogenesis and to lay a particular emphasis on the inter-organ crosstalk evidence.

Recent Advances in β2-Agonists for Treatment of Chronic Respiratory Diseases and Heart Failure

β₂-Adrenoceptor (β₂-AR) agonists are widely used as bronchodilators. The emerge of ultralong acting β₂-agonists is an important breakthrough in pulmonary medicine. In this review, we will provide mechanistic insights into the application of β₂-agonists in asthma, chronic obstructive pulmonary disease (COPD), and heart failure (HF). Recent studies in β-AR signal transduction have revealed opposing functions of the β₁-AR and the β₂-AR on cardiomyocyte survival. Thus, β₂-agonists and β-blockers in combination may represent a novel strategy for HF management. Allosteric modulation and biased agonism at the β₂-AR also provide a theoretical basis for developing drugs with novel mechanisms of action and pharmacological profiles. Overlap of COPD and HF presents a substantial clinical challenge but also a unique opportunity for evaluation of the cardiovascular safety of β₂-agonists. Further basic and clinical research along these lines can help us develop better drugs and innovative strategies for the management of these difficult-to-treat diseases.

Long Noncoding RNAs in the Regulation of Asthma: Current Research and Clinical Implications

Asthma is a chronic airway inflammatory disorder related to variable expiratory airflow limitation, leading to wheeze, shortness of breath, chest tightness, and cough. Its characteristic features include airway inflammation, airway remodeling and airway hyperresponsiveness. The pathogenesis of asthma remains extremely complicated and the detailed mechanisms are not clarified. Long noncoding RNAs (lncRNAs) have been reported to play a prominent role in asthma and function as modulators of various aspects in pathological progress of asthma. Here, we summarize recent advances of lncRNAs in asthma pathogenesis to guide future researches, clinical treatment and drug development, including their regulatory functions in the T helper (Th) 1/Th2 imbalance, Th17/T regulatory (Treg) imbalance, eosinophils dysfunction, macrophage polarization, airway smooth muscle cells proliferation, and glucocorticoid insensitivity.

Eriobotrya japonica leaf extract attenuates airway inflammation in ovalbumin-induced mice model of asthma

ETHNOPHARMACOLOGICAL RELEVANCE

Eriobotrya japonica leaves has a very long history of medicinal use as an anti-inflammatory and antitussive agent for bronchial inflammation.

AIM OF THE STUDY

The aim of this study was to evaluate the anti-inflammatory activities of Eriobotrya japonica (EJ) leaf water extract in an ovalbumin (OVA)-induced murine asthma model and human tracheal smooth muscle cell (HTSMC).

MATERIALS AND METHODS

Mice were sensitized by intra peritoneal OVA and challenged with nebulized OVA. EJ extract was administered orally at various dose. Bronchoalveolar lavage fluid (BALF) was quantified for nitric oxide (NO), eosinophil peroxidase (EPO), interleukin (IL)-4, IL-13 level and immunoglobulin (Ig) E was quantified in serum. Lung tissue sections were stained with hematoxylin and eosin for assessment of inflammatory cell infiltration whereas mucus production and goblet cell hyperplasia were studied by periodic acid schiff staining. Western blot was done for analysis of pERK1/2 expression and NFκB translocation in HTSMC whereas iNOS and COX-2 expression in RAW264.7 cell.

RESULTS

EJ significantly reduced the levels of BALF's NO, EPO, MMPs, IL-4, IL-13, and serum IgE. It also decreases inflammatory cell infiltration and mucus production. EJ also attenuated the proliferation of HTSMC, inhibits overexpression of ERK 1/2 and translocation of NFκB in HTSMC as well as iNOS and COX-2 expression in RAW 264.7 cell.

CONCLUSION

Present study suggest that, EJ effectively protects against allergic airway inflammation thus possessing potential therapeutic option for allergic asthma management.

Role of Platelet-Derived Growth Factor (PDGF) in Asthma as an Immunoregulatory Factor Mediating Airway Remodeling and Possible Pharmacological Target

Asthma is a chronic and heterogenic disease of the respiratory system, one of the most common lung diseases worldwide. The underlying pathologies, which are chronic inflammatory process and airway remodeling (AR), are mediated by numerous cells and cytokines. Particularly interesting in this field is the platelet-derived growth factor (PDGF), one of the members of the human growth factor family. In this article, the authors analyze the available data on the role of PDGF in asthma in experimental models and in human research. PDGF is expressed in airway by various cells contributing to asthma pathogenesis—mast cells, eosinophils, and airway epithelial cells. Research confirms the thesis that this factor is also secreted by these cells in the course of asthma. The main effects of PDGF on bronchi are the proliferation of airway smooth muscle (ASM) cells, migration of ASM cells into the epithelium and enhanced collagen synthesis by lung fibroblasts. The importance of AR in asthma is well recognized and new therapies should also aim to manage it, possibly targeting PDGFRs. Further studies on new and already existing drugs, mediating the PDGF signaling and related to asthma are necessary. Several promising drugs from the tyrosine kinase inhibitors group, including nilotinib, imatinib masitinib, and sunitinib, are currently being clinically tested and other molecules are likely to emerge in this field.

Endoplasmic Reticulum Stress and Mitochondrial Function in Airway Smooth Muscle

Inflammatory airway diseases such as asthma affect more than 300 million people world-wide. Inflammation triggers pathophysiology via such as tumor necrosis factor α (TNFα) and interleukins (e.g., IL-13). Hypercontraction of airway smooth muscle (ASM) and ASM cell proliferation are major contributors to the exaggerated airway narrowing that occurs during agonist stimulation. An emergent theme in this context is the role of inflammation-induced endoplasmic reticulum (ER) stress and altered mitochondrial function including an increase in the formation of reactive oxygen species (ROS). This may establish a vicious cycle as excess ROS generation leads to further ER stress. Yet, it is unclear whether inflammation-induced ROS is the major mechanism leading to ER stress or the consequence of ER stress. In various diseases, inflammation leads to an increase in mitochondrial fission (fragmentation), associated with reduced levels of mitochondrial fusion proteins, such as mitofusin 2 (Mfn2). Mitochondrial fragmentation may be a homeostatic response since it is generally coupled with mitochondrial biogenesis and mitochondrial volume density thereby reducing demand on individual mitochondrion. ER stress is triggered by the accumulation of unfolded proteins, which induces a homeostatic response to alter protein balance via effects on protein synthesis and degradation. In addition, the ER stress response promotes protein folding via increased expression of molecular chaperone proteins. Reduced Mfn2 and altered mitochondrial dynamics may not only be downstream to ER stress but also upstream such that a reduction in Mfn2 triggers further ER stress. In this review, we summarize the current understanding of the link between inflammation-induced ER stress and mitochondrial function and the role played in the pathophysiology of inflammatory airway diseases.

Elevated eosinophils, IL5 and IL8 in induced sputum in asthma patients with accelerated FEV1 decline

BACKGROUND

Some patients with asthma present with accelerated lung function decline. This phenomenon is mostly associated with severe exacerbations and with poor asthma control.

OBJECTIVE

Our aim was to detect the extent of FEV1 decline in patients with mild asthma and to discriminate clinical, functional and inflammatory factors associated with accelerated FEV1 decline.

METHODS

We recruited 50 patients with mild asthma for pulmonary function testing and induced sputum sampling 12-15 years after the initial diagnosis. In 33 patients, from whom sputum of a good quality was obtained, inflammatory cells were counted and concentrations of cytokines IL-2, IL-4, IL-5, IL-8, IL-10, IFN-γ, angiogenin and VEGF in the sputum were measured by cytometric bead array.

RESULTS

Eighteen of 33 patients presented with accelerated FEV1 decline of more than 30 ml/year, with a mean (SEM) of 43.2 (3.9) ml/year, compared to 15 control patients with a FEV1 decline of 14.4 (2.1) ml/year. In the accelerated FEV1 decline group, we found elevated sputum levels of IL5 with a median (IQR) of 1.8 (0.4-3.2) pg/ml vs. 0.2 (0.1-1.2) pg/ml, p = 0.04; IL8 with a mean (SEM) of 1503 (194) pg/ml vs. 938 (177) pg/ml, p = 0.04; and eosinophils with a median (IQR) of 223 (41-1020) cells/μl vs. 39 (1-190) cells/μl, p = 0.03. No significant differences in other measured parameters were detected between the two groups.

CONCLUSION

Elevated sputum eosinophils, IL5 and IL8, which have a potential to stimulate airway remodelling, might be a useful non-invasive biomarkers and therapeutic targets of accelerated FEV1 decline in asthma patients.

Sevoflurane Prevents Airway Remodeling via Downregulation of VEGF and TGF-β1 in Mice with OVA-Induced Chronic Airway Inflammation

Asthma is characterized by chronic airway inflammation, which is the underlying cause of airway remodeling featured by goblet cell hyperplasia, subepithelial fibrosis, and proliferation of smooth muscle. Sevoflurane has been used to treat life-threatening asthma and our previous study shows that sevoflurane inhibits acute lung inflammation in ovalbumin (OVA)-induced allergic mice. However, the effect of sevoflurane on airway remodeling in the context of chronic airway inflammation and the underlying mechanism are still unknown. Here, female C57BL/6 mice were used to establish chronic airway inflammation model. Hematoxylin and eosin (H&E), periodic acid-Schiff (PAS), and Sirius red (SR) staining were used to evaluate airway remodeling. Protein levels of α-SMA, VEGF, and TGF-β1 in lung tissues were detected by western blotting analyses and immunohistochemistry staining. Results showed that inhalation of sevoflurane inhibited chronic airway inflammation including inflammatory cell infiltration and pro-inflammatory cytokine production in BALF of the OVA-challenged mice. Meanwhile, sevoflurane suppressed airway thickening, goblet cell hyperplasia, smooth muscle hyperplasia, collagen deposition, and fiber hyperplasia in the lung tissues of the mice with airway remodeling. Most notably, sevoflurane inhibited the OVA-induced expressions of VEGF and TGF-β1. These results suggested that sevoflurane effectively inhibits airway remodeling in mouse model of chronic airway inflammation, which may be due to the downregulation of VEGF and TGF-β1in lung tissues. Therefore, our results indicate a potential role of sevoflurane in inhibiting airway remodeling besides its known suppression effect on airway inflammation, and support the use of sevoflurane in treating severe asthma in ICU.

Bronchial thermoplasty decreases airway remodelling by blocking epithelium-derived heat shock protein-60 secretion and protein arginine methyltransferase-1 in fibroblasts

Bronchial thermoplasty (BT) is to date the only therapy that provides a lasting reduction in airway wall remodelling. However, the mechanism of action of BT is not well understood. This study aimed to characterise the changes of remodelling regulating signalling pathways by BT in asthma.Bronchoalveolar lavage fluid (BALF) was obtained from eight patients with severe asthma before and after BT. Primary bronchial epithelial cells were isolated from 23 patients before (n=66) and after (n=62) BT. Epithelial cell culture supernatant (Epi.S) was collected and applied to primary fibroblasts.Epithelial cells obtained from asthma patients after BT proliferated significantly faster compared with epithelial cells obtained before BT. In airway fibroblasts, BALF or Epi.S obtained before BT increased CCAAT enhancer-binding protein-β (C/EBPβ) expression, thereby downregulating microRNA-19a. This upregulated extracellular signal-regulated kinase-1/2 (ERK1/2) expression, protein arginine methyltransferase-1 (PRMT1) expression, cell proliferation and mitochondrial mass. BALF or Epi.S obtained after BT reduced the expression of C/EBPβ, ERK1/2, peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1α), PRMT1 and mitochondrial mass in airway fibroblasts. Proteome and transcriptome analyses indicated that epithelial cell-derived heat shock protein-60 (HSP60) is the main mediator of BT effects on fibroblasts. Further analysis suggested that HSP60 regulated PRMT1 expression, which was responsible for the increased mitochondrial mass and α-smooth muscle actin expression by asthmatic fibroblasts. These effects were ablated after BT. These results imply that BT reduces fibroblast remodelling through modifying the function of epithelial cells, especially by reducing HSP60 secretion and subsequent signalling pathways that regulate PRMT1 expression.We therefore hypothesise that BT decreases airway remodelling by blocking epithelium-derived HSP60 secretion and PRMT1 in fibroblasts.

Effects of ATP-competitive and function-selective ERK inhibitors on airway smooth muscle cell proliferation

Increased airway smooth muscle (ASM) cell mass and secretory functions are characteristics of airway inflammatory diseases, such as asthma. To date, there are no effective therapies to combat ASM cell proliferation, which contributes to bronchoconstriction and airway obstruction. Growth factors such as platelet-derived growth factor (PDGF) and the activation of the ERK1/2 are major regulators of ASM cell proliferation and airway remodeling in asthma. However, given the ubiquitous expression and multiple functions of ERK1/2, complete inhibition of ERK1/2 using ATP-competitive inhibitors may lead to unwanted off-target effects. Alternatively, we have identified compounds that are designed to target substrate docking sites and act as function-selective inhibitors of ERK1/2 signaling. Here, we show that both function-selective and ATP-competitive ERK1/2 inhibitors are effective at inhibiting PDGF-mediated proliferation, collagen production, and IL-6 secretion in ASM cells. Proteomic analysis revealed that both types of inhibitors had similar effects on reducing proteins related to TGF-β and IL-6 signaling that are relevant to airway remodeling. However, function-selective ERK1/2 inhibitors caused fewer changes in protein expression compared with ATP-competitive inhibitors. These studies provide a molecular basis for the development of function-selective ERK1/2 inhibitors to mitigate airway remodeling in asthma with defined regulation of ERK1/2 signaling.-Defnet, A. E., Huang, W., Polischak, S., Yadav, S. K., Kane, M. A., Shapiro, P., Deshpande, D. A. Effects of ATP-competitive and function-selective ERK inhibitors on airway smooth muscle cell proliferation.

Bnip3 regulates airway smooth muscle cell focal adhesion and proliferation

Increased airway smooth muscle (ASM) mass is a key contributor to airway narrowing and airway hyperresponsiveness in asthma. Besides conventional pathways and regulators of ASM proliferation, recent studies suggest that changes in mitochondrial morphology and function play a role in airway remodeling in asthma. In this study, we aimed at determining the role of mitochondrial Bcl-2 adenovirus E1B 19 kDa-interacting protein, Bnip3, in the regulation of ASM proliferation. Bnip3 is a member of the Bcl-2 family of proteins critical for mitochondrial health, mitophagy, and cell survival/death. We found that Bnip3 expression is upregulated in ASM cells from asthmatic donors compared with that in ASM cells from healthy donors and transient downregulation of Bnip3 expression in primary human ASM cells using an siRNA approach decreased cell adhesion, migration, and proliferation. Furthermore, Bnip3 downregulation altered the structure (electron density) and function (cellular ATP levels, membrane potential, and reacitve oxygen species generation) of mitochondria and decreased expression of cytoskeleton proteins vinculin, paxillin, and actinin. These findings suggest that Bnip3 via regulation of mitochondria functions and expression of adhesion proteins regulates ASM adhesion, migration, and proliferation. This study reveals a novel role for Bnip3 in ASM functions and establishes Bnip3 as a potential target in mitigating ASM remodeling in asthma.

Bitter Taste Receptors for Asthma Therapeutics

Clinical management of asthma and chronic obstructive pulmonary disease (COPD) has primarily relied on the use of beta 2 adrenergic receptor agonists (bronchodilators) and corticosteroids, and more recently, monoclonal antibody therapies (biologics) targeting specific cytokines and their functions. Although these approaches provide relief from exacerbations, questions remain on their long-term efficacy and safety. Furthermore, current therapeutics do not address progressive airway remodeling (AR), a key pathological feature of severe obstructive lung disease. Strikingly, agonists of the bitter taste receptors (TAS2Rs) deliver robust bronchodilation, curtail allergen-induced inflammatory responses in the airways and regulate airway smooth muscle (ASM) cell proliferation and mitigate features of AR in vitro and in animal models. The scope of this review is to provide a comprehensive and systematic insight into our current understanding of TAS2Rs with an emphasis on the molecular events that ensue TAS2R activation in distinct airway cell types and expand on the pleiotropic effects of TAS2R targeting in mitigating various pathological features of obstructive lung diseases. Finally, we will discuss specific opportunities that could help the development of selective agonists for specific TAS2R subtypes in the treatment of asthma.

Semaphorin 3A Is Effective in Reducing Both Inflammation and Angiogenesis in a Mouse Model of Bronchial Asthma

Semaphorin 3A (sema3A) belongs to the sub-family of the immune semaphorins that function as regulators of immune-mediated inflammation. Sema3A is a membrane associated molecule on T regulatory cells and on B regulatory cells. Being transiently ligated to the cell surface of these cells it is suggested to be a useful marker for evaluating their functional status. In earlier studies, we found that reduced sema3A concentration in the serum of asthma patients as well as reduced expression by Treg cells correlates with asthma disease severity. Stimulation of Treg cells with recombinant sema3A induced a significant increase in FoxP3 and IL-10 expression. To find out if sema3A can be of benefit to asthma patients, we evaluated the effect of sema3A injection in a mouse model of asthma. BALB\c-mice were sensitized using ovalbumin (OVA) + adjuvant for 15 days followed by OVA aerosol inhalation over five consecutive days. Four hours following air ways sensitization on each of the above days- 15 of these mice were injected intraperitoneally with 50 μg per mouse of recombinant human sema3A-FR and the remaining 15 mice were injected with a similarly purified vehicle. Five days later the mice were sacrificed, broncheo-alveolar lavage (BAL) was collected and formalin-fixed lung biopsies taken and analyzed. In sema3A treated mice, only 20% of the bronchioles and arterioles were infiltrated by inflammatory cells as compared to 90% in the control group (p = 0.0079). In addition, eosinophil infiltration was also significantly increased in the control group as compared with the sema3A treated mice. In sema3A treated mice we noticed only a small number of mononuclear and neutrophil cells in the BAL while in the control mice, the BAL was enriched with mononuclear and neutrophil cells. Finally, in the control mice, angiogenesis was significantly increased in comparison with sema3A treated mice as evidenced by the reduced concentration of microvessels in the lungs of sema3A treated mice. To conclude, we find that in this asthma model, sema3A functions as a potent suppressor of asthma related inflammation that has the potential to be further developed as a new therapeutic for the treatment of asthma.

Anti-inflammatory and anti-remodeling effects of myrtenol in the lungs of asthmatic rats: Histopathological and biochemical findings

INTRODUCTION

Asthma is a chronic inflammatory disease of the airways. In this study, we evaluated the anti-inflammatory effects of myrtenol on the inflammatory indices in the pulmonary parenchyma and airways and on the inflammatory and oxidative indices of the bronchoalveolar lavage fluid (BALF) of asthmatic rats.

METHODS

The allergic asthma was induced by sensitization (two weeks) followed by the inhalation of ovalbumin (four weeks). Animals were divided into two main groups: (1) Histopathology, and (2) measurement of inflammatory and oxidative biomarkers in the BALF. Each main group was subdivided into four subgroups: Control, Asthma, Asthma+Dexamethasone and Asthma+Myrtenol. (-)-Myrtenol (50mg/kg) or Dexamethasone (2.5mg/kg) was administered intraperitoneally once a day for one week, at the end of the inhalation period. On day 50, lung histopathologic parameters and inflammatory indices in BALF including INF-γ, IL-10, IL-1β, and TNF-α and oxidative stress biomarkers (MDA, SOD, and GPX) were measured.

RESULT

In the Asthma group, leukocyte infiltration, the thickness of smooth muscle and epithelium of airways wall and the number of goblet cells increased. Myrtenol reduced all of the above-mentioned indices except the epithelium thickness. It also inhibited the increase in BALF IL-1β, TNF-α and MDA and increased the levels of INF-γ, IL-10 and SOD.

CONCLUSION

Our results suggest that myrtenol reduced damage caused by experimental asthma by reducing the inflammatory indices, normalizing the level of interleukins and balancing oxidative stress in the lungs. It also prevented airway remodeling. Myrtenol may be suggested as a potent herbal medicine for the treatment of allergic asthma.

Mitochondrial regulation of airway smooth muscle functions in health and pulmonary diseases

Mitochondria are important for airway smooth muscle physiology due to their diverse yet interconnected roles in calcium handling, redox regulation, and cellular bioenergetics. Increasing evidence indicates that mitochondria dysfunction is intimately associated with airway diseases such as asthma, IPF and COPD. In these pathological conditions, increased mitochondrial ROS, altered bioenergetics profiles, and calcium mishandling contribute collectively to changes in cellular signaling, gene expression, and ultimately changes in airway smooth muscle contractile/proliferative properties. Therefore, understanding the basic features of airway smooth muscle mitochondria and their functional contribution to airway biology and pathology are key to developing novel therapeutics for airway diseases. This review summarizes the recent findings of airway smooth muscle mitochondria focusing on calcium homeostasis and redox regulation, two key determinants of physiological and pathological functions of airway smooth muscle.

Potential Role of Interleukin-25/Interleukin-33/Thymic Stromal Lymphopoietin-Fibrocyte Axis in the Pathogenesis of Allergic Airway Diseases

Objective:

Allergic airway diseases (AADs) are a group of heterogeneous disease mediated by T-helper type 2 (Th2) immune response and characterized with airway inflammation and remodeling, including allergic asthma, allergic rhinitis, and chronic rhinosinusitis with allergic background. This review aimed to discuss the abnormal epithelial-mesenchymal crosstalk in the pathogenesis of AADs.

Data Sources:

Articles referred in this review were collected from the database of PubMed published in English up to January 2018.

Study Selection:

We had done a literature search using the following terms “allergic airway disease OR asthma OR allergic rhinitis OR chronic sinusitis AND IL-25 OR IL-33 OR thymic stromal lymphopoietin OR fibrocyte”. Related original or review articles were included and carefully analyzed.

Results:

It is now believed that abnormal epithelial-mesenchymal crosstalk underlies the pathogenesis of AADs. However, the key regulatory factors and molecular events involved in this process still remain unclear. Epithelium-derived triple cytokines, including interleukin (IL)-25, IL-33, and thymic stromal lymphopoietin (TSLP), are shown to act on various target cells and promote the Th2 immune response. Circulating fibrocyte is an important mesenchymal cell that can mediate tissue remodeling. We previously found that IL-25-circulating fibrocyte axis was significantly upregulated in patients with asthma, which may greatly contribute to asthmatic airway inflammation and remodeling.

Conclusions:

In view of the redundancy of cytokines and “united airway” theory, we propose a new concept that IL-25/IL-33/TSLP-fibrocyte axis may play a vital role in the abnormal epithelial-mesenchymal crosstalk in some endotypes of AADs. This novel idea will guide potential new intervention schema for the common treatment of AADs sharing common pathogenesis in the future.

Novel eosinophilic gene expression networks associated with IgE in two distinct asthma populations

BACKGROUND

Asthma represents a significant public health burden; however, novel biological therapies targeting immunoglobulin E (IgE)-mediated pathways have widened clinical treatment options for the disease.

OBJECTIVE

In this study, we sought to identify gene transcripts and gene networks involved in the determination of serum IgE levels in people with asthma that can help inform the development of novel therapeutic agents.

METHODS

We analysed gene expression data from a cross-sectional study of 326 Costa Rican children with asthma, aged 6 to 12 years, from the Genetics of Asthma in Costa Rica Study and 610 young adults with asthma, aged 16 to 25 years, from the Childhood Asthma Management Program trial. We utilized differential gene expression analysis and performed weighted gene coexpression network analysis on 25 060 genes, to identify gene transcripts and network modules associated with total IgE, adjusting for age and gender. We used pathway enrichment analyses to identify key biological pathways underlying significant modules. We compared findings that replicated between both populations.

RESULTS

We identified 31 transcripts associated with total IgE that replicated between the two study cohorts. These results were notable for increased eosinophil-related transcripts (including IL5RA, CLC, SMPD3, CCL23 and CEBPE). Pathway enrichment identified the regulation of T cell tolerance as important in the determination of total IgE levels, supporting a key role for IDO1.

CONCLUSIONS AND CLINICAL RELEVANCE

These results provide robust evidence that biologically meaningful gene expression profiles (relating to eosinophilic and regulatory T cell pathways in particular) associated with total IgE levels can be identified in individuals diagnosed with asthma during childhood. These profiles and their constituent genes may represent novel therapeutic targets.

Suppressive Effect of 4-Hydroxy-2-(4-Hydroxyphenethyl) Isoindoline-1,3-Dione on Ovalbumin-Induced Allergic Asthma

4-Hydroxy-2-(4-hydroxyphenethyl)isoindoline-1,3-dione (PD1) is a synthetic phthalimide derivative of a marine compound. PD1 has peroxisome proliferator-activated receptor (PPAR) γ agonistic and anti-inflammatory effects. This study aimed to investigate the effect of PD1 on allergic asthma using rat basophilic leukemia (RBL)-2H3 mast cells and an ovalbumin (OVA)-induced asthma mouse model. In vitro, PD1 suppressed β-hexosaminidase activity in RBL-2H3 cells. In the OVA-induced allergic asthma mouse model, increased inflammatory cells and elevated Th2 and Th1 cytokine levels were observed in bronchoalveolar lavage fluid (BALF) and lung tissue. PD1 administration decreased the numbers of inflammatory cells, especially eosinophils, and reduced the mRNA and protein levels of the Th2 cytokines including interleukin (IL)-4 and IL-13, in BALF and lung tissue. The severity of inflammation and mucin secretion in the lungs of PD1-treated mice was also less. These findings indicate that PD1 could be a potential compound for anti-allergic therapy.

MMP12 -82 A>G Promoter Polymorphism in Bronchial Asthma in a Population of Central Bulgaria

A characteristic feature of inflamed lungs in bronchial asthma (BA) is airway remodeling. Due to limited information on this topic in the literature, we aimed to explore the possible role of polymorphisms in the promoter region of the macrophage elastase gene MMP12 82A>G (rs2276109) as a predisposing factor for BA in an ethnic Bulgarian population. Using restriction fragment length polymorphism analysis of polymerase chain reaction-amplified fragments (PCR-RFLP), we performed genotype analysis of 58 patients and 119 control individuals. We found statistically significant differences in the distribution of genotypes (P = .008) and alleles (P = .004) between patients and nonaffected controls. In the dominant model, carriers of the G allele genotypes had 3.6-fold lower risk for BA, compared with those with the AA genotype, after adjustment for age and sex (odds ratio [OR], -0.277; 95% confidence interval [CI], .12-.65; P = .003). The results of our study suggest that the variant G allele of the MMP12 -82 A>G promoter polymorphism might be considered protective for development of BA in ethnic Bulgarian adults residing in central Bulgaria.

New targets for resolution of airway remodeling in obstructive lung diseases

Airway remodeling (AR) is a progressive pathological feature of the obstructive lung diseases, including asthma and chronic obstructive pulmonary disease (COPD). The pathology manifests itself in the form of significant, progressive, and (to date) seemingly irreversible changes to distinct respiratory structural compartments. Consequently, AR correlates with disease severity and the gradual decline in pulmonary function associated with asthma and COPD. Although current asthma/COPD drugs manage airway contraction and inflammation, none of these effectively prevent or reverse features of AR. In this review, we provide a brief overview of the features and putative mechanisms affecting AR. We further discuss recently proposed strategies with promise for deterring or treating AR.

TRPC3 overexpression and intervention in airway smooth muscle of ovalbumin-induced hyperresponsiveness and remodeling

Transient receptor potential canonical channel 3 (TRPC3) proteins function as non-voltage-gated Ca²⁺ -permeable channels and play divergent roles in many processes of pathophysiology. The purpose of this study was to determine the relationship between TRPC3 expression and airway hyperresponsiveness and remodeling in ovalbumin-induced asthmatic Kunming mice. Mice were sensitized and challenged by ovalbumin to establish asthmatic model. Hematoxylin-eosin staining, hydroxyproline assay, and isometric tracheal ring force measurement were used to evaluate airway remodeling and hyperresponsiveness in asthmatic mice. Western blot was performed to detect the expression of TRPC3 proteins. MTT assay was used to measure the proliferation of airway smooth muscle cells. TRPC3 protein expression increased in airway smooth muscle of asthmatic mice. GdCl₃ , a nonspecific TRPC blocker, attenuated the contractile force of airway smooth muscle. Fetal bovine serum stimulated airway smooth muscle cells proliferation and augmented TRPC3 protein expression. Both TRPC3 blockade by GdCl₃ or specific TRPC3 antibodies and gene silencing by siRNA inhibited the proliferation of airway smooth muscle cells. In contrast, the current drugs treatment for asthma such as Dexamethasone and Aminophylline had no effects on TRPC3 protein overexpression. Therefore, TRPC3 protein overexpression may be involved in airway smooth muscle hyperresponsiveness and remodeling in asthmatic mice, providing evidence for a new direction of asthma pathogenesis research and a new target for drug intervention.

Death From Butane Inhalation Abuse in Teenagers: Two New Case Studies and Review of the Literature

The ready availability of butane makes butane abuse frequent. Fatalities are rare. This study presents two cases of death by butane overdose. The postmortem analyses were carried out using headspace gas chromatography-mass spectrometry. It revealed femoral blood butane concentrations of 18 and 22 mg/L, respectively, as well as specific combinations of adjuvants in each victim. In one of the victims, brain and fatty tissue also contained butane, pointing to chronic consumption. The originality of this study is to show that the identification of specific combinations of adjuvants can be helpful for identifying the brand of deodorant used. Also, sampling the skin and mucosa can help identify the method of drug delivery. The histological examination documented both the direct toxic effect of the gas on the respiratory mucosa and signs of chronic abuse. Volatile substance intoxications should be systematically considered in case of sudden death in a teenager.

Bupleurum chinense extract ameliorates an OVA-induced murine allergic asthma through the reduction of the Th2 and Th17 cytokines production by inactivation of NFκB pathway

Bupleurum chinense belongs to the Bupleurum spp. family that has been used in traditional herbal medicine for over thousand years. It has been reported to have anti-inflammatory, anti-oxidant, hepato-protective, antipyretic, analgesic, anti-fibrotic and immunomodulatory effect. However, the effect of B. Chinense on allergic asthma remains unclear. This study investigated the immunomodulatory effects of B. Chinense extracts (BCE) on airway inflammation in asthmatic mice model. In the ovalbumin (OVA)-induced allergic asthma model, we evaluated the number of total cells, differential inflammatory cells and the production of proinflammatory cytokines in bronchoalveolar lavage fluid (BALF) and lung homogenate as well as histological structure. The levels of NFκB p65, IκBα, p-NFκB p65, p-IκBα and the total immunoglobulin (Ig) E, anti-OVA IgE, anti-OVA IgG were also examined. The oral administration of 200mg/kg BCE inhibited the accumulation of inflammatory cells especially eosinophils in BALF. Also, BCE regulated the imbalance of Th1, Th2 and Th17-related production, with attenuated the expression of GATA3, IL-1β, IL-4, IL-5, IL-6, TNF-α and RORγt, IL-17A in BALF and lung homogenate, meanwhile, up-regulated the secretion of INF-γ in lung homogenate. The levels of IgE, anti-OVA IgE, anti-OVA IgG1 and anti-OVA IgG2a were also suppressed by BCE treatment in serum. Futhermore, BCE inhibited the proinflammatory cytokines via inactivation of NFκB p65 phosphorylation and IκBα degradation in cytoplasm. The histological analysis showed that the infiltration of inflammatory cells, mucus hypersecretion and collagen fiber deposits were ameliorated in BCE treated mice. In addition, BCE induced the functional differentiation of naive CD4+ T cells forward to Th1 and Tr1 through producing INF-γ and IL-10. These results suggest that BCE may have therapeutic potential for treating allergic asthma through inhibiting Th2/Th17 cytokines production by inactivation of NFκB pathway.

Nasal airway epithelial cell IL-6 and FKBP51 gene expression and steroid sensitivity in asthmatic children

Background

Many asthmatic patients exhibit uncontrolled asthma despite high-dose inhaled corticosteroids (ICS). Airway epithelial cells (AEC) have distinct activation profiles that can influence ICS response.

Objectives

A pilot study to identify gene expression markers of AEC dysfunction and markers of corticosteroid sensitivity in asthmatic and non-asthmatic control children, for comparison with published reports in adults.

Methods

AEC were obtained by nasal brushings and primary submerged cultures, and incubated in control conditions or in the presence of 10 ng/ml TNFalpha, 10^-8M dexamethasone, or both. RT-PCR-based expression of FKBP51 (a steroid hormone receptor signalling regulator), NF-kB, IL-6, LIF (an IL-6 family neurotrophic cytokine), serpinB2 (which inhibits plasminogen activation and promotes fibrin deposition) and porin (a marker of mitochondrial mass) were determined.

Results

6 patients without asthma (median age 11yr; min-max: 7–13), 8 with controlled asthma (11yr, 7–13; median daily fluticasone dose = 100 μg), and 4 with uncontrolled asthma (12yr, 7–14; 1000 μg fluticasone daily) were included. Baseline expression of LIF mRNA was significantly increased in uncontrolled vs controlled asthmatic children. TNFalpha significantly increased LIF expression in uncontrolled asthma. A similar trend was observed regarding IL-6. Dexamethasone significantly upregulated FKBP51 expression in all groups but the response was blunted in asthmatic children. No significant upregulation was identified regarding NF-kB, serpinB2 and porin.

Conclusion

LIF and FKBP51 expression in epithelial cells were the most interesting markers of AEC dysfunction/response to corticosteroid treatment.

Bitter taste receptor agonists alter mitochondrial function and induce autophagy in airway smooth muscle cells

Airway remodeling, including increased airway smooth muscle (ASM) mass, is a hallmark feature of asthma and COPD. We previously identified the expression of bitter taste receptors (TAS2Rs) on human ASM cells and demonstrated that known TAS2R agonists could promote ASM relaxation and bronchodilation and inhibit mitogen-induced ASM growth. In this study, we explored cellular mechanisms mediating the antimitogenic effect of TAS2R agonists on human ASM cells. Pretreatment of ASM cells with TAS2R agonists chloroquine and quinine resulted in inhibition of cell survival, which was largely reversed by bafilomycin A1, an autophagy inhibitor. Transmission electron microscope studies demonstrated the presence of double-membrane autophagosomes and deformed mitochondria. In ASM cells, TAS2R agonists decreased mitochondrial membrane potential and increased mitochondrial ROS and mitochondrial fragmentation. Inhibiting dynamin-like protein 1 (DLP1) reversed TAS2R agonist-induced mitochondrial membrane potential change and attenuated mitochondrial fragmentation and cell death. Furthermore, the expression of mitochondrial protein BCL2/adenovirus E1B 19-kDa protein-interacting protein 3 (Bnip3) and mitochondrial localization of DLP1 were significantly upregulated by TAS2R agonists. More importantly, inhibiting Bnip3 mitochondrial localization by dominant-negative Bnip3 significantly attenuated cell death induced by TAS2R agonist. Collectively the TAS2R agonists chloroquine and quinine modulate mitochondrial structure and function, resulting in ASM cell death. Furthermore, Bnip3 plays a central role in TAS2R agonist-induced ASM functional changes via a mitochondrial pathway. These findings further establish the cellular mechanisms of antimitogenic effects of TAS2R agonists and identify a novel class of receptors and pathways that can be targeted to mitigate airway remodeling as well as bronchoconstriction in obstructive airway diseases.

Regulation of airway inflammation and remodeling in asthmatic mice by TLR3/TRIF signal pathway

This paper aims to investigate the effect of Toll-like receptors 3 (TLR3)/TIR-domain-containing adapter-inducing interferon-β (TRIF) signal pathway on the airway inflammation and remodeling in asthmatic mice. C57BL/6 and TLR3^-/- mice were randomly divided into three groups (10 mice per group), including Control group (mice inhaled phosphate buffer saline (PBS)), Asthma group (mice inhaled ovalbumin (OVA)) and polyriboinosinic-ribocytidylic acid (poly (I: C)) group (asthmatic mice were injected intraperitoneally with TLR3 agonist poly (I: C)). Hematoxylin-eosin (HE) staining, Wright-Giemsa staining, Enzyme-linked immunosorbent assay (ELISA), Immunohistochemistry, Hydroxyproline assay, quantitative real time polymerase chain reaction (qRT-PCR) and Western blot were used to assess for the indices of airway inflammation and remodeling. In terms of WT mice, all asthma groups with or without the addition of poly (I: C) showed exaggerated inflammation and remodeling in the airways as compared to Control group, which were more seriously in poly (I: C) group than Asthma group. Furthermore, we observed the significant inhibition of airway inflammation and remodeling in the TLR3^-/- mice in both Asthma no matter with or without addition of poly (I: C) than the WT mice. TLR3 knockout could obviously relieve the airway inflammation and remodeling in asthma through inhibiting TLR3/TRIF signaling pathway.

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

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

Angiotensin-(1–7) decreases the expression of collagen I via TGF-β1/Smad2/3 and subsequently inhibits fibroblast–myofibroblast transition

Previous studies have shown that the RAS (renin–angiotensin system) might participate in airway remodelling in asthma. As a main component of the RAS, Ang-(1–7) [angiotensin-(1–7)] has been reported in few studies regarding its protective effect on asthma. However, the functional roles and relevant signalling pathways of Ang-(1–7) have not been well illustrated. In the present study, we analysed the effect of Ang-(1–7) on AngII (angiotensin II)-induced HLF (human lung fibroblast)–MF (myofibroblast) transition by detecting Col-I (collagen type I), TGF-β1 (transforming growth factor-β1) and α-SMA (α-smooth muscle actin) expression. We explored further the possible signalling pathways involved in HLF–MF transition. Our results showed that Ang-(1–7) could down-regulate the expression of Col-I, α-SMA and TGF-β1/Smad2/3 (all P<0.05). A significant decrease was found in phosphorylation of PI3K (phosphoinositide 3-kinase), Akt, p38-MAPK (mitogen-activated protein kinase) and JNK (c-Jun N-terminal kinase) signalling pathways during HLF–MF transition (all P<0.05). Our data suggests that Ang-(1–7) decreases the expression of Col-I via TGF-β1/Smad2/3 and subsequently inhibits HLF–MF transition.

A HuR/TGF-β1 feedback circuit regulates airway remodeling in airway smooth muscle cells

Background

Asthma is a worldwide health burden with an alarming prevalence. For years, asthma-associated airway injury remains elusive. Transforming growth factor β1 (TGF-β1) is a pleiotropic cytokine that has been shown to be involved in the synthesis of the matrix molecules associated with airway remodeling. Human antigen R (HuR), the member of the Hu RNA-binding protein family, can bind to a subset of short-lived mRNAs in their 3′ untranslated regions (UTR). However, the functional roles and relevant signaling pathways of HuR in airway remodeling have not been well illustrated. Thus, we aim to explore the relationship between HuR and TGF-β1 in platelet derived growth factor(PDGF)-induced airway smooth muscle (ASM) cells and asthmatic animal.

Methods

Cultured human ASM cells were stimulated by PDGF for 0, 6, 12 and 24 h. Western blotting, RT-PCR and immunofluoresence were used to detect the expression of HuR, TGF-β1, α-smooth muscle actins (α-SMA) and collagen type I (Col-I). Then knockdown of HuR, flow cytomerty was used to detect the morphological change and western blotting for functionally change of ASM cells. Furthermore, the interference of TGF-β1 and exogenous TGF-β1 were implemented to testify the influence on HuR. A murine OVA-driven allergic model based on sensitization and challenge was developed. The inflammatory response was measured by bronchoalveolar lavage fluid (BALF), airway damage was analyzed by hematoxylin and eosin staining, airway remodeling was assessed by sirius red staining and periodic acid-schiff staining, the expression level of HuR, TGF-β1 and α-SMA were measured by RT-PCR, western blotting and immunohistochemistry.

Results

Here, we found that PDGF elevated HuR expression both at mRNA and protein level in cultured ASM cells at a time-dependent manner, which was simultaneously accompanied by the enhanced expression of TGF-β1, α-SMA and Col-I. Further study revealed that the knockdown of HuR significantly increased the apoptosis of ASM cells and dampened TGF-β1, Col-I and α-SMA expression. However, interfering TGF-β1 with siRNA or extra addition of TGF-β1, HuR could restore its production as well as Col-I. Compared with normal mice stimulating with PBS, OVA-induced mice owned high amount of inflammatory cells, such as eosinophils, lymphocytes and neutrophils except macrophages. HE staining showed accumulation of inflammatory cells surrounding bronchiole and sirius red staining distinguished collagen type I and III deposition around the bronchiole. Higher abundance of HuR, TGF-β1 and α-SMA were verified in OVA-induced mice than PBS-induced mice by RT-PCR, western blotting and immunohistochemistry.

Conclusions

A HuR/TGF-β1 feedback circuit was established to regulate airway remodeling in vivo and in vitro and targeting this feedback has considerable potential for the intervention of asthma.