Azithromycin ameliorates OVA-induced airway remodeling in Balb/c mice via suppression of epithelial-to-mesenchymal transition

Research trends on airway remodeling: A bibliometrics analysis

Background

Airway remodeling is an essential pathological basis of respiratory diseases such as asthma and COPD, which is significantly related to pulmonary function and clinical symptoms. And pulmonary disease can be improved by regulating airway remodeling. This study aimed to establish a knowledge map of airway remodeling to clarify current research hotspots and future research trends.

Methods

A comprehensive search was performed to analyze all relevant articles on airway remodeling using the Web of Science Core Collection Database from January 01, 2004 to June 03, 2023.2 reviewers screened the retrieved literature. Besides, the CiteSpace (6.2. R3) and VOSviewer (1.6.19) were utilized to visualize the research focus and trend regarding the effect of airway remodeling.

Results

A total of 4077 articles about airway remodeling were retrieved. The United States is the country with the most published literature, underscoring the country's role in airway remodeling. In recent years, China has been the country with the fastest growth in the number of published literature, suggesting that China will play a more critical role in airway remodeling in the future. From the perspective of co-operation among countries, European co-operation was closer than Asian co-operation. The co-citation analysis showed that 98,313 citations were recorded in 3594 articles, and 25 clusters could be realized. In recent years, Burst detection shows that oxidative stress and epithelial-mesenchymal transition are hot words.

Conclusions

Based on the bibliometric analysis of airway remodeling studies in the past 20 years, a multi-level knowledge structure map was drawn, it mainly includes countries, institutions, research fields, authors, journals, keywords and so on. The research directions represented by obstructive airway disease, PDGF-BB treatment of airway smooth muscle, allergen-induced airway remodeling, extracellular matrix, and non-coding RNA are the research hotspots in the field of airway remodeling. While the risk factors for airway remodeling, the application of new noninvasively assessing tools, biomarkers as well as The molecular mechanism represented by EMT and autophagy had been frontiers in recent years.

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.

Exosome miR-223-3p in the bone marrow-derived mesenchymal stem cells alleviates the inflammation and airway remodeling through NLRP3-induced ASC/Caspase-1/GSDMD signaling pathway

Asthma is one of the most common chronic respiratory diseases in the world. Exploration and understanding of the pathogenesis of epithelial-mesenchymal transition in airway epithelial cells, and the development of new molecular drugs targeted at airway inflammation and remodeling have become the key and hot points in the prevention and treatment of asthma. Emerging evidence has proven that miRNAs are strongly associated with numerous chronic respiratory diseases including asthma, but the involved molecular mechanisms have not been revealed. In the present study, we successfully isolated exosomes from BMMSCs and found that the derived exosomes could improve airway inflammation and remodeling in ovalbumin-induced asthma rats. Furthermore, we found that the highly expressed miR-223-3p in exosomes might play a key pivotal role in the protective effects on airway remodeling and asthma by regulating the NLRP3-induced ASC/Caspase-1/GSDMD signaling pathway. These results provided a promising molecule candidate and target for the therapy of asthma.

Epithelial cell dysfunction in chronic rhinosinusitis: the epithelial-mesenchymal transition

INTRODUCTION

Epithelial-mesenchymal transition (EMT) is a type of epithelial cell dysfunction, which is widely present in the nasal mucosa of patients with chronic rhinosinusitis (CRS), especially CRS with nasal polyps, and contributes to pathogenesis of the disease. EMT is mediated via complex mechanisms associated with multiple signaling pathways.

AREAS COVERED

We have summarized the underlying mechanisms and signaling pathways promoting EMT in CRS. Strategies or drugs/agents targeting the genes and pathways related to the regulation of EMT are also discussed for their potential use in the treatment of CRS and asthma. A literature search of studies published in English from 2000 to 2023 was conducted using the PubMed database, employing CRS, EMT, signaling, mechanisms, targeting agents/drugs, as individual or combinations of search terms.

EXPERT OPINION

EMT in nasal epithelium not only leads to epithelial cell dysfunction but also plays an important role in nasal tissue remodeling in CRS. A comprehensive understanding of the mechanisms underlying EMT and the development of drugs/agents targeting these mechanisms may provide new treatment strategies for CRS.

CTRP3 regulates NF-κB and TGFβ1/Smad3 pathways to alleviate airway inflammation and remodeling in asthmatic mice induced by OVA

BACKGROUND

Asthma is a common illness with chronic airway inflammation. C1q/tumor necrosis factor (TNF)-related protein 3 (CTRP3) plays a vital role ininflammatory response, but its effect on asthma is imprecise. Herein, we analyzed the functions of CTRP3 in asthma.

METHODS

The BALB/c mice were randomized into four groups: control, ovalbumin (OVA), OVA+vector, and OVA+CTRP3. The asthmatic mice model was established by OVA stimulation. Overexpression of CTRP3 was implemented by the transfection of corresponding adeno-associated virus 6 (AAV6). The contents of CTRP3, E-cadherin, N-cadherin, smooth muscle alpha-actin (α-SMA), phosphorylated (p)-p65/p65, transforming growth factor-beta 1 (TGFβ1), and p-Smad3/Smad3 were determined by Western blot analysis. The quantity of total cells, eosinophils, neutrophils, and lymphocytes in bronchoalveolar lavage fluid (BALF) was assessed by using a hemocytometer. The contents of tumor necrosis factor-α and interleukin-1β in BALF were examined by enzyme-linked immunesorbent serologic assay. The lung function indicators and airway resistance (AWR) were measured. The bronchial and alveolar structures were evaluated by hematoxylin and eosin staining and sirius red staining.

RESULTS

The CTRP3 was downregulated in mice of OVA groups; however, AAV6-CTRP3 treatment markedly upregulated the expression of CTRP3. Upregulation of CTRP3 diminished asthmatic airway inflammation by decreasing the number of inflammatory cells and the contents of proinflammatory factors. CTRP3 markedly lessened AWR and improved lung function in OVA-stimulated mice. Histological analysis found that CTRP3 alleviated OVA-induced airway remodeling in mice. Moreover, CTRP3 modulated NF-κB and TGFβ1/Smad3 pathways in OVA-stimulated mice.

CONCLUSION

CTRP3 alleviated airway inflammation and remodeling in OVA-induced asthmatic mice via regulating NF-κB and TGFβ1/Smad3 pathways.

A cell wall invertase modulates resistance to fusarium crown rot and sharp eyespot in common wheat

Fusarium crown rot (FCR) and sharp eyespot (SE) are serious soil-borne diseases in wheat and its relatives that have been reported to cause wheat yield losses in many areas. In this study, the expression of a cell wall invertase gene, TaCWI-B1, was identified to be associated with FCR resistance through a combination of bulk segregant RNA sequencing and genome resequencing in a recombinant inbred line population. Two bi-parental populations were developed to further verify TaCWI-B1 association with FCR resistance. Overexpression lines and ethyl methanesulfonate (EMS) mutants revealed TaCWI-B1 positively regulating FCR resistance. Determination of cell wall thickness and components showed that the TaCWI-B1-overexpression lines exhibited considerably increased thickness and pectin and cellulose contents. Furthermore, we found that TaCWI-B1 directly interacted with an alpha-galactosidase (TaGAL). EMS mutants showed that TaGAL negatively modulated FCR resistance. The expression of TaGAL is negatively correlated with TaCWI-B1 levels, thus may reduce mannan degradation in the cell wall, consequently leading to thickening of the cell wall. Additionally, TaCWI-B1-overexpression lines and TaGAL mutants showed higher resistance to SE; however, TaCWI-B1 mutants were more susceptible to SE than controls. This study provides insights into a FCR and SE resistance gene to combat soil-borne diseases in common wheat.

Azithromycin suppresses TGF-β1-related epithelial-mesenchymal transition in airway epithelial cells via targeting RACK1

Transforming growth factor-β1 (TGF-β1) associated epithelial-mesenchymal transition (EMT) contributes to multiple respiration diseases via Smad or MAPKs pathway. Our previous study has demonstrated that the typical macrolide antibiotic, azithromycin (AZM) played a notable anti-EMT role in ovalbumin (OVA)-challenged mice. However, the precise mechanism of AZM on TGF-β1 mediated EMT in bronchial epithelial cells is still unclear. The purpose of this study was to elucidate whether azithromycin targeting RACK1 inhibits TGF-β1 mediated EMT in vitro. The results showed that AZM significantly inhibited the expression of RACK1 and the activation of the downstream JNK, ERK, and Smad3 signaling pathways, thereby suppressing the migration of bronchial epithelial cells and reversing the TGF-β1-induced EMT. The effect of AZM on TGF-β1 mediated EMT in vitro is dependent on the dose of AZM. Although RACK1 has been shown to regulate IRE1α expression with siRACK1 transfection, there was no direct interaction between IRE1α and AZM. On the contrary, weak interaction between AZM and RACK1 was predicted with molecular docking. In summary, AZM targets RACK1 to trigger downstream JNK, ERK, and Smad3 signaling pathways and is an effective anti-EMT drug for bronchial epithelial cells in a dose-dependent manner.

Collagen Triple Helix Repeat Containing 1 Deficiency Protects Against Airway Remodeling and Inflammation in Asthma Models In Vivo and In Vitro

Asthma is a chronic inflammatory disease characterized by airway remodeling and lung inflammation. Collagen triple helix repeat containing 1 (CTHRC1), a glycoprotein, is involved in multiple pathological processes, including inflammation and fibrosis. However, the function of CTHRC1 in asthma remains unclear. In the present study, the mouse asthma model was successfully generated by sensitizing and challenging mice with ovalbumin (OVA). CTHRC1 expression at both RNA and protein levels was significantly upregulated in lung tissues of asthmatic mice. Asthmatic mice exhibited significant airway remodeling as evidenced by increased bronchial wall and smooth muscle cell layer thickness, goblet cell hyperplasia and collagen deposition, and epithelial-mesenchymal transition (EMT), but those characteristics were reversed by CTHRC1 silencing. The cell model with transforming growth factor-β1 (TGF-β1) induction in bronchial epithelial cells (BEAS-2B) was conducted to verify the effects of CTHRC1 on EMT, a classic mechanism that mediates airway remodeling. The results showed that TGF-β1 stimulation increased CTHRC1 expression, and CTHRC1 knockdown inhibited TGF-β1-induced EMT. OVA-treated mice also showed increased inflammatory cell infiltration and the production of OVA-specific immunoglobulin E (IgE), interleukin (IL)-4, IL-5, and IL-13, which were decreased by CTHRC1 downregulation. The effects of CTHRC1 on OVA-induced airway inflammation were further determined by treating BEAS-2B cells with IL-13, in which CTHRC1 knockdown reduced the IL-13-induced secretion of pro-inflammatory factors, including IL-4 and IL-5. In conclusion, these results indicate that CTHRC1 silencing attenuates asthmatic airway remodeling and inflammation in vivo and in vitro, suggesting that CTHRC1 may be a potential target for asthma treatment.

New insights into autophagy in inflammatory subtypes of asthma

Asthma is a heterogeneous airway disease characterized by airway inflammation and hyperresponsiveness. Autophagy is a self-degrading process that helps maintain cellular homeostasis. Dysregulation of autophagy is involved in the pathogenesis of many diseases. In the context of asthma, autophagy has been shown to be associated with inflammation, airway remodeling, and responsiveness to drug therapy. In-depth characterization of the role of autophagy in asthma can enhance the understanding of the pathogenesis, and provide a theoretical basis for the development of new biomarkers and targeted therapy for asthma. In this article, we focus on the relationship of autophagy and asthma, and discuss its implications for asthma pathogenesis and treatment.

Recent Advances in Nanomaterials for Asthma Treatment

Asthma is a chronic airway inflammatory disease with complex mechanisms, and these patients often encounter difficulties in their treatment course due to the heterogeneity of the disease. Currently, clinical treatments for asthma are mainly based on glucocorticoid-based combination drug therapy; however, glucocorticoid resistance and multiple side effects, as well as the occurrence of poor drug delivery, require the development of more promising treatments. Nanotechnology is an emerging technology that has been extensively researched in the medical field. Several studies have shown that drug delivery systems could significantly improve the targeting, reduce toxicity and improve the bioavailability of drugs. The use of multiple nanoparticle delivery strategies could improve the therapeutic efficacy of drugs compared to traditional delivery methods. Herein, the authors presented the mechanisms of asthma development and current therapeutic methods. Furthermore, the design and synthesis of different types of nanomaterials and micromaterials for asthma therapy are reviewed, including polymetric nanomaterials, solid lipid nanomaterials, cell membranes-based nanomaterials, and metal nanomaterials. Finally, the challenges and future perspectives of these nanomaterials are discussed to provide guidance for further research directions and hopefully promote the clinical application of nanotherapeutics in asthma treatment.

CD5L attenuates allergic airway inflammation by expanding CD11chigh alveolar macrophages and inhibiting NLRP3 inflammasome activation via HDAC2

Allergic asthma is an airway inflammatory disease dominated by type 2 immune responses and there is currently no curative therapy for asthma. CD5-like antigen (CD5L) has been known to be involved in a variety of inflammatory diseases. However, the role of CD5L in allergic asthma remains unclear. In the present study, mice were treated with recombinant CD5L (rCD5L) during house dust mite (HDM) and ovalbumin (OVA) challenge to determine the role of CD5L in allergic asthma, and the underlying mechanism was further explored. Compared with PBS group, serum CD5L levels of asthmatic mice were significantly decreased, and the levels of CD5L in lung tissues and bronchoalveolar lavage fluid (BALF) were significantly increased. CD5L reduced airway inflammation and Th2 immune responses in asthmatic mice. CD5L exerted its anti-inflammatory function by increasing CD11c^high alveolar macrophages (CD11c^high AMs), and the anti-inflammatory role of CD11c^high AMs in allergic asthma was confirmed by CD11c^high AMs depletion and transfer assays. In addition, CD5L increased the CD5L⁺ macrophages and inhibited NLRP3 inflammasome activation by increasing HDAC2 expression in lung tissues of asthmatic mice. Hence, our study implicates that CD5L has potential usefulness for asthma treatment.

Azithromycin inhibits mucin secretion, mucous metaplasia, airway inflammation and airways hyperresponsiveness in mice exposed to house dust mite extract

Excessive production, secretion and retention of abnormal mucus is a pathologic feature of many obstructive airways diseases including asthma, chronic obstructive pulmonary disease, cystic fibrosis and bronchiectasis. Azithromycin is an antibiotic that also possesses immunomodulatory and mucoregulatory activities, which may contribute to the clinical effectiveness of azithromycin in these obstructive airway diseases. The current study investigated these non-antibiotic activities of azithromycin (or saline) in mice exposed daily to intranasal house dust mite (HDM) extract (or SHAM inoculation) for 10 days. HDM-exposed mice exhibited airways hyperresponsiveness to aerosolised methacholine, a pronounced mixed eosinophilic and neutrophilic inflammatory response, increased airway smooth muscle (ASM) thickness and elevated levels of epithelial mucin staining (compared to SHAM mice). Azithromycin (50 mg/kg s.c., 2 h prior to each HDM exposure) significantly attenuated HDM-induced airways hyperresponsiveness to methacholine, airways inflammation (bronchoalveolar lavage eosinophil and neutrophils numbers, and cytokine/chemokine levels), and epithelial mucin staining (mucous metaplasia) (P<0.05, 2-way ANOVA). Isolated tracheal segments of HDM-exposed mice secreted Muc5ac and Muc5b (above baseline levels) in response to exogenous ATP. Moreover, ATP-induced secretion of mucins was significantly attenuated in segments obtained from azithromycin-treated, HDM-exposed mice (P<0.05, 2-way ANOVA). In additional ex vivo studies, ATP-induced secretion of Muc5ac from HDM-exposed tracheal segments was inhibited by in vitro exposure to azithromycin. In vitro azithromycin also inhibited ATP-induced secretion of Muc5ac and Muc5b in tracheal segments from IL-13-exposed mice. In summary, azithromycin inhibited ATP-induced mucin secretion and airways inflammation in HDM-exposed mice, both of which are likely to contribute to suppression of airways hyperresponsiveness.

Factors Determining Plasticity of Responses to Drugs

The plasticity of responses to drugs is an ever-present confounding factor for all aspects of pharmacology, influencing drug discovery and development, clinical use and the expectations of the patient. As an introduction to this Special Issue of the journal IJMS on pharmacological plasticity, we address the various levels at which plasticity appears and how such variability can be controlled, describing the ways in which drug responses can be affected with examples. The various levels include the molecular structures of drugs and their receptors, expression of genes for drug receptors and enzymes involved in metabolism, plasticity of cells targeted by drugs, tissues and clinical variables affected by whole body processes, changes in geography and the environment, and the influence of time and duration of changes. The article provides a rarely considered bird’s eye view of the problem and is intended to emphasize the need for increased awareness of pharmacological plasticity and to encourage further debate.

Effects of intranasal azithromycin on features of cigarette smoke-induced lung inflammation

Airflow limitation in chronic obstructive pulmonary disease (COPD) is the result of exaggerated airway fibrosis and obliteration of the small airways due to persistent inflammation, and an impaired anti-oxidant response. EMT has been implicated as an active signalling process in cigarette smoke (CS)-induced lung pathology, and macrolide Azithromycin (AZT) use has gained interest in treating COPD. Here, we tested effectiveness of intra-nasal AZT alone and in combination with dexamethasone (DEX) on CS-induced acute lung inflammation. Human alveolar epithelial cells (A549) were treated with CS extract (CSE) for 48 h, and male Balb/c mice were exposed to CS (3 cigarettes-3 times/day) for 4 days. The effects of AZT alone (0.25 and 1.25 μM, in vitro; 0.5 and 5 mg/kg, in vivo) or in combination with DEX (1 μM, in vitro; 1 mg/kg, in vivo) on CS-induced cellular cytotoxicity, oxidative stress, inflammation, and lung function were assessed. AZT alone and in combination with DEX significantly inhibited the CS (E)-induced expression of mesenchymal protein markers and the regulatory protein β-catenin. Furthermore, AZT by itself or in combination with DEX significantly suppressed CS-induced expression of the proinflammtory cytokines TNFα, IL1β and IL6 and prevented pNFkB. Mechanistically, AZT restored the CS-induced reduction in anti-oxidant transcription factor NRF2 and upregulated HDAC2 levels, thereby repressing inflammatory gene expression. Beneficial effects of AZT functionally translated in improved lung mechanics in vivo. Further preclinical and clinical studies are warranted to fully establish and validate the therapeutic efficacy of AZT as a mono- or combination therapy for the treatment of COPD.

Effects of azithromycin on bronchial remodeling in the natural model of severe neutrophilic asthma in horses

Steroid resistance in asthma has been associated with neutrophilic inflammation and severe manifestations of the disease. Macrolide add-on therapy can improve the quality of life and the exacerbation rate in refractory cases, possibly with greater effectiveness in neutrophilic phenotypes. The mechanisms leading to these beneficial effects are incompletely understood and whether macrolides potentiate the modulation of bronchial remodeling induced by inhaled corticosteroids (ICS) is unknown. The objective of this study was to determine if adding azithromycin to ICS leads to further improvement of lung function, airway inflammation and bronchial remodeling in severe asthma. The combination of azithromycin (10 mg/kg q48h PO) and inhaled fluticasone (2500 µg q12h) was compared to the sole administration of fluticasone for five months in a randomized blind trial where the lung function, airway inflammation and bronchial remodeling (histomorphometry of central and peripheral airways and endobronchial ultrasound) of horses with severe neutrophilic asthma were assessed. Although the proportional reduction of airway neutrophilia was significantly larger in the group receiving azithromycin, the lung function and the peripheral and central airway smooth muscle mass decreased similarly in both groups. Despite a better control of airway neutrophilia, azithromycin did not potentiate the other clinical effects of fluticasone.

Azithromycin Attenuates Bleomycin-Induced Pulmonary Fibrosis Partly by Inhibiting the Expression of LOX and LOXL-2

Pulmonary fibrosis (PF) is a chronic and progressive process of tissue repair. Azithromycin (AZM) may be beneficial for the treatment of PF because AZM has anti-inflammatory and immune regulatory roles and inhibits remodeling, but the mechanism is not entirely clear. In this study, we established a mouse PF model induced by bleomycin (BLM) and primary mouse lung fibroblasts stimulated by transforming growth factor (TGF)-β1 to explore the possible mechanisms of AZM in PF. Results showed that AZM reduces mortality and lung inflammation and attenuates BLM-induced PF in mice. AZM effectively reduced the expression of α-smooth muscle actin (SMA) and type I collagen. Meanwhile, expression of lysyl oxidase (LOX) and lysyl oxidase-like protein (LOXL)-2 in the lung tissue of mice after AZM treatment was significantly lower than in the BLM group. In addition, this study found that AZM significantly inhibits the TGF-β1/Smad and JNK/c-Jun signaling pathways in vivo, and expression of a-SMA, type I collagen, LOX and LOXL-2 in the lung tissue of mice treated with AZM was significantly lower than that in the BLM group. In vitro, AZM also effectively inhibited type I collagen, LOX, LOXL-2 and JNK-c-Jun signaling pathways in TGF-β1-stimulated primary mouse fibroblasts, and this effect was similar to that of a JNK-specific inhibitor (SP600125). In conclusion, AZM effectively attenuated BLM-induced PF in mice, which may play a role by partially inhibiting the JNK/c-Jun and TGF-β1/Smad signaling pathways and reducing production of LOX and LOXL2.

Nonantimicrobial Actions of Macrolides: Overview and Perspectives for Future Development

Macrolides are among the most widely prescribed broad spectrum antibacterials, particularly for respiratory infections. It is now recognized that these drugs, in particular azithromycin, also exert time-dependent immunomodulatory actions that contribute to their therapeutic benefit in both infectious and other chronic inflammatory diseases. Their increased chronic use in airway inflammation and, more recently, of azithromycin in COVID-19, however, has led to a rise in bacterial resistance. An additional crucial aspect of chronic airway inflammation, such as chronic obstructive pulmonary disease, as well as other inflammatory disorders, is the loss of epithelial barrier protection against pathogens and pollutants. In recent years, azithromycin has been shown with time to enhance the barrier properties of airway epithelial cells, an action that makes an important contribution to its therapeutic efficacy. In this article, we review the background and evidence for various immunomodulatory and time-dependent actions of macrolides on inflammatory processes and on the epithelium and highlight novel nonantibacterial macrolides that are being studied for immunomodulatory and barrier-strengthening properties to circumvent the risk of bacterial resistance that occurs with macrolide antibacterials. We also briefly review the clinical effects of macrolides in respiratory and other inflammatory diseases associated with epithelial injury and propose that the beneficial epithelial effects of nonantibacterial azithromycin derivatives in chronic inflammation, even given prophylactically, are likely to gain increasing attention in the future. SIGNIFICANCE STATEMENT: Based on its immunomodulatory properties and ability to enhance the protective role of the lung epithelium against pathogens, azithromycin has proven superior to other macrolides in treating chronic respiratory inflammation. A nonantibiotic azithromycin derivative is likely to offer prophylactic benefits against inflammation and epithelial damage of differing causes while preserving the use of macrolides as antibiotics.

Effect of azithromycin on bronchial wall thickness in severe persistent asthma: A double-blind placebo-controlled randomized clinical trial

BACKGROUND

Azithromycin reduced airway remodeling in animal models of asthma. However, its effect on human subjects has not been studied yet. This study aimed to investigate the effect of long-term treatment with azithromycin on airways wall thickness in patients with severe persistent asthma.

METHODS

In this randomized, double-blind, placebo-controlled clinical trial, patients with severe persistent asthma received azithromycin (250 mg, BID, three days a week), prednisolone (5 mg, BID), or placebo for eight months in three separate groups in addition to the standard therapy. The improvement in right upper lobe apical segmental bronchus (RB1) wall thickness obtained by high resolution computed tomography was set as the primary outcome. Secondary outcomes included: cough severity, dyspnea severity, asthma control test (ACT) score, asthma exacerbation rate, pulmonary function tests, and fractional exhaled nitric oxide (FENO).

RESULTS

Seventy-eight out of ninety randomized subjects completed eight months of treatment with azithromycin (n = 25), prednisolone (n = 27), or placebo (n = 26). Bronchial wall thickness percentage did not change significantly in any of the groups. However, the inner radius and lumen area of azithromycin and prednisolone-treated subjects increased significantly (p < 0.05 for both). Azithromycin also significantly improved the dyspnea severity, ACT score, FENO, and FEV1, FEF_25-75, and FEV1/FVC (p < 0.05 for all). Cough severity or asthma exacerbation rate did not change significantly after eight months of treatment with azithromycin.

CONCLUSION

Long-term treatment with azithromycin increased lumen radius and lumen area in patients with severe persistent asthma. However, there was no significant change in wall thickness in any of the treatment groups.

TRIAL REGISTRATION

IRCT.com (IRCT20091111002695N8).

Interleukin-27 Inhibits Epithelial-Mesenchymal Transition in Ovalbumin-Induced Mice Bronchial Epithelial Cells

The epithelial-mesenchymal transition (EMT) of bronchial epithelial cells is a critical mechanism involved in transforming growth factor beta 1 (TGF-β1) induced asthma airway remodeling. Previous study has shown that interleukin 27 (IL-27) attenuates EMT in alveolar epithelial cells, but its effects on the BEAS-2B human bronchial epithelial cell line EMT remain unknown. Herein, we explored the effects of IL-27 on BEAS-2B EMT in vivo and in vitro. In the in vivo experiments, we found that IL-27 nose-drip therapy alleviated airway remodeling, increased the epithelial phenotypic marker epithelial-cadherin (E-cadherin), and decreased the mesenchymal phenotypic marker alpha-smooth muscle actin (α-SMA) compared with the asthmatic control group. We also found that IL-27 suppressed the signal transducer and activator of transcription (STAT3) in the lung tissue of asthmatic mice. in vitro, TGF-β1-induced EMT changes, including downregulation of E-cadherin and upregulation of α-SMA, were suppressed by IL-27 treatment. Additionally, STAT3 phosphorylation was activated by TGF-β1, whereas IL-27 inhibited the activation of TGF-β1 induced STAT3 phosphorylation. Our findings indicated that IL-27 could inhibit airway remodeling by attenuating bronchial epithelial cell EMT in vivo and in vitro. Therefore, IL-27 may be a beneficial therapeutic option targeting asthmatic airway remodeling.

MiR-21-5p in Macrophage-Derived Exosomes Targets Smad7 to Promote Epithelial Mesenchymal Transition of Airway Epithelial Cells

Background

Asthma is usually associated with airway inflammation and airway remodeling. Epithelial mesenchymal transition (EMT) often occurs in airway remodeling. The purpose of this study is to identify the effect of miR-21-5p and Smad7 signaling pathway in macrophage-derived exosomes on EMT of airway epithelial cells.

Methods

HE staining and Masson staining were used to verify the successful establishment of the asthma model. The levels of epithelial cell adhesion factor and stromal cell markers were detected by Western blot. The levels of miR-21-5p were detected by qRT-PCR. The expression of miR-21-5p in lung tissue was further verified by fluorescence in situ hybridization (FISH). Exosome morphology was observed by transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA). Luciferase reporter assay was applied to analyze the interaction of miR-21-5p with Smad7.

Results

The expression of miR-21-5p was upregulated in macrophages of rats in vivo with OVA-induced asthma. In vitro cultured alveolar macrophages stimulated by LPS could secrete exosomes with high levels of miR-21-5p. The exosome-derived miR-21-5p promotes EMT in rat tracheal epithelial cells through TGFβ1/Smad signaling pathway by downregulating Smad7. This process can be blocked by miR-21-5p inhibitor.

Conclusion

Rat alveolar macrophages produced high levels of miR-21-5p-containing exosomes, which transported miR-21-5p to tracheal epithelial cells, thus promoting EMT through TGF-β1/Smad signaling pathway by targeting Smad7.

RACK1 plays a critical role in mast cell secretion and Ca2+ mobilization by modulating F-actin dynamics

Although RACK1 is known to act as a signaling hub in immune cells, its presence and role in mast cells (MCs) is undetermined. MC activation via antigen stimulation results in mediator release and is preceded by cytoskeleton reorganization and Ca2+ mobilization. In this study, we found that RACK1 was distributed throughout the MC cytoplasm both in vivo and in vitro. After RACK1 knockdown (KD), MCs were rounded, and the cortical F-actin was fragmented. Following antigen stimulation, in RACK1 KD MCs, there was a reduction in cortical F-actin, an increase in monomeric G-actin and a failure to organize F-actin. RACK1 KD also increased and accelerated degranulation. CD63+ secretory granules were localized in F-actin-free cortical regions in non-stimulated RACK1 KD MCs. Additionally, RACK1 KD increased antigen-stimulated Ca2+ mobilization, but attenuated antigen-stimulated depletion of ER Ca2+ stores and thapsigargin-induced Ca2+ entry. Following MC activation there was also an increase in interaction of RACK1 with Orai1 Ca2+-channels, β-actin and the actin-binding proteins vinculin and MyoVa. These results show that RACK1 is a critical regulator of actin dynamics, affecting mediator secretion and Ca2+ signaling in MCs. This article has an associated First Person interview with the first author of the paper.

Azithromycin inhibited oxidative stress and apoptosis of high glucose-induced podocytes by inhibiting STAT1 pathway

Azithromycin (AZM) has a therapeutic effect on diabetes, but there is no report on whether AZM has a therapeutic effect on diabetic nephropathy (DN) and its specific mechanism. Cell survival was detected by CCK-8. The expression of the inflammatory factors TNF-α, IL-1β, and IL-6 was determined by ELISA. The expression of inflammatory proteins MCP-1, NLPR3, and ASC was detected by western blot. The expression of MDA, LDH, and SOD was detected by the appropriate kit. Apoptosis was detected by flow cytometry and apoptosis-related proteins Bcl-2, Bax, Caspase-3, 6, 9, and Cleaved caspase-3, 6, 9 were detected by western blot. In addition, the expression of STAT1 was detected by western blot. AZM can increase the activity of high glucose-induced podocytes (p < .05). After high glucose induction, the expression of TNF-α, IL-1β, and IL-6 was increased and the expression of MCP-1, NLPR3, and ASC proteins was also increased (p < .001). When AZM was added, the expression of all the above-mentioned proteins was decreased (p < .001). In addition, MDA, LDH, and SOD were increased after high glucose induction, while decreased after AZM treatment (p < .001). AZM can inhibit apoptosis and the expression of Bax and Cleaved caspase-3, 6, 9, and promote the expression of Bcl-2 (p < .001). Furthermore, the expression of STAT1 was increased after high glucose induction, while the expression of STAT1 was decreased after AZM action (p < .01). By adding a STAT1 agonist IFN-γ, the effects of AZM on inflammation, oxidative stress, and apoptosis of high glucose-induced podocytes were inhibited (p < .05). AZM inhibited inflammation, oxidative stress, and apoptosis of high glucose-induced podocytes by inhibiting STAT1 pathway.

The Protective Effects of Maresin 1 in the OVA-Induced Asthma Mouse Model

Asthma is a chronic inflammatory disease that cannot be cured. Maresin 1 (MaR1) is a specific lipid synthesized by macrophages that exhibits powerful anti-inflammatory effects in various inflammatory diseases. The goal of this study was to evaluate the effect of MaR1 on allergic asthma using an ovalbumin- (OVA-) induced asthma model. Thirty BALB/c mice were randomly allocated to control, OVA, and MaR1 + OVA groups. Mice were sacrificed 24 hours after the end of the last challenge, and serum, bronchoalveolar lavage fluid (BALF), and lung tissue were collected for further analysis. Western blotting was used to measure the protein level of IκBα, the activation of the NF-κB signaling pathway, and the expression of NF-κB downstream inflammatory cytokines. Quantitative real-time polymerase chain reactions (qRT-PCRs) were used to evaluate the expression levels of COX-2 and ICAM-1 in lung tissues. We found that high doses of MaR1 were most effective in preventing OVA-induced inflammatory cell infiltration and excessive mucus production in lung tissue, reducing the number of inflammatory cells in the BALF and inhibiting the expression of serum or BALF-associated inflammatory factors. Furthermore, high-dose MaR1 treatment markedly suppressed the activation of the NF-κB signaling pathway, the degradation of IκBα, and the expression of inflammatory genes downstream of NF-κB, such as COX-2 and ICAM-1, in the OVA-induced asthma mouse model. Our findings indicate that MaR1 may play a critical role in OVA-induced asthma and may be therapeutically useful for the management of asthma.

Epithelial-Mesenchymal Transition in Atopy: A Mini-Review

Atopic diseases, particularly atopic dermatitis (AD), asthma, and allergic rhinitis (AR) share a common pathogenesis of inflammation and barrier dysfunction. Epithelial to mesenchymal transition (EMT) is a process where epithelial cells take on a migratory mesenchymal phenotype and is essential for normal tissue repair and signal through multiple inflammatory pathways. However, while links between EMT and both asthma and AR have been demonstrated, as we outline in this mini-review, the literature investigating AD and EMT is far less well-elucidated. Furthermore, current studies on EMT and atopy are mostly animal models or ex vivo studies on cell cultures or tissue biopsies. The literature covered in this mini-review on EMT-related barrier dysfunction as a contributor to AD as well as the related (perhaps resultant) atopic diseases indicates a potential for therapeutic targeting and carry treatment implications for topical steroid use and environmental exposure assessments. Further research, particularly in vivo studies, may greatly advance the field and translate into benefit for patients and families.

miR‑155‑5p downregulation inhibits epithelial‑to‑mesenchymal transition by targeting SIRT1 in human nasal epithelial cells

Epithelial-to-mesenchymal transition (EMT) in nasal epithelial cells is involved with tissue remodeling of nasal polyps. The present study investigated the molecular mechanisms through which miR-155-5p regulated EMT in chronic rhinosinusitis (CRS). Patients were divided into the following groups: CRSsNP, CRS without nasal polyposis group, CRSwNP, CRS with nasal polyposis and controls. The expression of transforming growth factor (TGF)-β1, EMT markers, sirtuin 1 (SIRT1) and miR-155-5p were determined by western blotting and reverse transcription-quantitative PCR. Cell morphology following TGF-β1 treatment in the presence of miR-155-5p inhibitors or controls was observed under a microscope. Target genes and potential binding sites between miR-155-5p and SIRT1 were predicted by TargetScan and confirmed using dual-luciferase reporter assay. In patients with CRS, the expression levels of E-cadherin were downregulated and the expression levels of TGF-β1, mesenchymal markers and miR-155-5p were upregulated. Additionally, these changes in expression levels were reduced or increased to a greater extent in the CRSwNP group compared with the CRSsNP group. Furthermore, TGF-β1 expression promoted EMT in human nasal epithelial cells (HNEpCs) and upregulated miR-155-5p expression. These effects were reversed by miR-155-5p inhibitors. Additionally, SIRT1 was predicted as a target gene of miR-155-5p. Downregulation of miR-155-5p upregulated epithelial marker expression and downregulated mesenchymal marker expression by regulating SIRT1. Therefore, the downregulation of miR-155-5p inhibited EMT in HNEpCs by targeting SIRT1.

Emodin ameliorates ovalbumin-induced airway remodeling in mice by suppressing airway smooth muscle cells proliferation

Increased number of airway smooth muscle cells (ASMCs) is a characteristic of airway remodeling in asthma. In this study we investigated whether emodin alleviated airway remodeling in a murine asthma model and reduced the proliferation of ASMCs in vitro. We provided in vivo evidence suggesting that intraperitoneal injection of emodin (20 mg/kg) 1 h prior to OVA challenge apparently alleviated the thickness of airway smooth muscle, the mass of alpha-smooth muscle actin (α-SMA), collagen deposition, epithelial damage, goblet cell hyperplasia, airway inflammation and airway hyperresponsiveness (AHR) in lung tissue. Meanwhile, we found that emodin suppressed the activation of the Akt pathway in lungtissue of allergic mouse models. Additionally, we found that emodin inhibited cellular proliferation and Akt activation in a dose-dependent manner in vitro. Furthermore, LY294002, an inhibitor for PI3K, abrogated serum-induced phosphorylation of Akt, and decreased the proliferation of ASMCs. These findings indicated that emodin alleviated ASMCs proliferation by inhibiting PI3K/Akt pathway in vivo and in vitro, which may provide a potential therapeutic option for airway smooth muscle remodeling in asthma.

Randomised study of the immunomodulatory effects of azithromycin in severely asthmatic horses

Neutrophilic inflammation is believed to contribute to the airway obstruction and remodelling in equine asthma. Azithromycin, an antibiotic with immunomodulatory properties, reduces pulmonary neutrophilia and hyper-responsiveness in human asthmatics and decreases airway remodelling in rodent models of asthma. It was therefore hypothesised that azithromycin would improve lung function, mucus accumulation and central airway remodelling by decreasing luminal neutrophilia in severe equine asthma. The effects of a 10-day treatment with either azithromycin or ceftiofur, an antimicrobial without immune-modulating activity, were assessed using a blind, randomised, crossover design with six severe asthmatic horses in clinical exacerbation. Lung function, tracheal mucus accumulation, tracheal wash bacteriology, bronchial remodelling, airway neutrophilia and mRNA expression of proinflammatory cytokines (interleukin (IL)-8, IL-17A, IL-1β, tumour necrosis factor-α) in bronchoalveolar lavage fluid were evaluated. Azithromycin decreased the expression of IL-8 (P=0.03, one-tailed) and IL-1β (P=0.047, one-tailed) but failed to improve the other variables evaluated. Ceftiofur had no effect on any parameter. The reduction of neutrophilic chemoattractants (IL-8, IL-1β) justifies further efforts to investigate the effects of a prolonged treatment with macrolides on airway neutrophilia and remodelling. The lack of efficacy of ceftiofur suggests that severe equine asthma should not be treated with antibiotics at first-line therapy.

Epithelial-Mesenchymal Transition in Asthma Airway Remodeling Is Regulated by the IL-33/CD146 Axis

Epithelial-mesenchymal transition (EMT) is essential in asthma airway remodeling. IL-33 from epithelial cells is involved in pulmonary fibrosis. CD146 has been extensively explored in cancer-associated EMT. Whether IL-33 regulates CD146 in the EMT process associated with asthma airway remodeling is still largely unknown. We hypothesized that EMT in airway remodeling was regulated by the IL-33/CD146 axis. House dust mite (HDM) extract increased the expression of IL-33 and CD146 in epithelial cells. Increased expression of CD146 in HDM-treated epithelial cells could be blocked with an ST2-neutralizing antibody. Moreover, HDM-induced EMT was dependent on the CD146 and TGF-β/SMAD-3 signaling pathways. IL-33 deficiency decreased CD146 expression and alleviated asthma severity. Similarly, CD146 deficiency mitigated EMT and airway remodeling in a murine model of chronic allergic airway inflammation. Furthermore, CD146 expression was significantly elevated in asthma patients. We concluded that IL-33 from HDM extract-treated alveolar epithelial cells stimulated CD146 expression, promoting EMT in airway remodeling in chronic allergic inflammation.

Dual role of RACK1 in airway epithelial mesenchymal transition and apoptosis

Airway epithelial apoptosis and epithelial mesenchymal transition (EMT) are two crucial components of asthma pathogenesis, concomitantly mediated by TGF‐β1. RACK1 is the downstream target gene of TGF‐β1 shown to enhancement in asthma mice in our previous study. Balb/c mice were sensitized twice and challenged with OVA every day for 7 days. Transformed human bronchial epithelial cells, BEAS‐2B cells were cultured and exposed to recombinant soluble human TGF‐β1 to induced apoptosis (30 ng/mL, 72 hours) and EMT (10 ng/mL, 48 hours) in vitro, respectively. siRNA and pharmacological inhibitors were used to evaluate the regulation of RACK1 protein in apoptosis and EMT. Western blotting analysis and immunostaining were used to detect the protein expressions in vivo and in vitro. Our data showed that RACK1 protein levels were significantly increased in OVA‐challenged mice, as well as TGF‐β1‐induced apoptosis and EMT of BEAS‐2B cells. Knockdown of RACK1 (siRACK1) significantly inhibited apoptosis and decreased TGF‐β1 up‐regulated EMT related protein levels (N‐cadherin and Snail) in vitro via suppression of JNK and Smad3 activation. Moreover, siSmad3 or siJNK impaired TGF‐β1‐induced N‐cadherin and Snail up‐regulation in vitro. Importantly, JNK gene silencing (siERK) also impaired the regulatory effect of TGF‐β1 on Smad3 activation. Our present data demonstrate that RACK1 is a concomitant regulator of TGF‐β1 induces airway apoptosis and EMT via JNK/Smad/Snail signalling axis. Our findings may provide a new insight into understanding the regulation mechanism of RACK1 in asthma pathogenesis.

House dust mite induces Sonic hedgehog signaling that mediates epithelial‑mesenchymal transition in human bronchial epithelial cells

Epithelial‑mesenchymal transition (EMT) provides a valuable source of fibroblasts that produce extracellular matrix in airway walls. The Sonic hedgehog (SHH) signaling pathway plays an essential role in regulating tissue turnover and homeostasis. SHH is strikingly upregulated in the bronchial epithelia during asthma. Snail1 is a major target of SHH signaling, which regulates EMT and fibroblast motility. The present study was designed to ascertain whether the combination of house dust mite (HDM) and transforming growth factor β1 (TGF‑β1) could induce EMT via the SHH signaling pathway in human bronchial epithelial cells (HBECs). HBEC cultures were treated with HDM/TGF‑β1 for different periods of time. The involvement of SHH signaling and EMT biomarkers was evaluated by quantitative real‑time PCR, western blotting and immunofluorescence staining. Small‑interfering RNA (siRNA) for glioma‑associated antigen‑1 (Gli1) or cyclopamine was used to inhibit SHH signaling in HBECs. HBECs stimulated by HDM/TGF‑β1 exhibited morphological features of EMT. E‑cadherin (an epithelial marker) was decreased after a 72‑h exposure to HDM/TGF‑β1 compared to that in the control cells, and the expression of type I collagen and FSP1 (mesenchymal markers) was increased. HDM/TGF‑β1 activated the SHH signaling pathway in HBECs, which led to Gli1 nuclear translocation and the transcriptional activation of Snail1 expression. Moreover, gene silencing or the pharmacological inhibition of Gli1 ameliorated EMT. In summary, these findings suggest that HDM/TGF‑β1 may induce EMT in HBECs via an SHH signaling mechanism. Inhibition of SHH signaling may be a novel therapeutic method for preventing airway remodeling in asthma.

Management of asthma COPD overlap

OBJECTIVE

To review the latest literature on management approaches to patients with asthma chronic obstructive pulmonary disease (COPD) overlap (ACO).

DATA SOURCES

Studies and reports were identified from the databases of PubMed/Medline and ClinicalTrials.gov from the US National Institutes of Health and the Cochrane Register of Controlled Trials.

STUDY SELECTIONS

Studies on the management of asthma, COPD, and ACO were included in this review.

RESULTS

Patients with asthma COPD overlap tend to have greater morbidity than those with asthma or COPD alone, but the information on the best therapeutic approach to this group of patients is still limited. Current treatment recommendations rely on expert opinions, roundtable discussions, and strategy documents, because most clinical studies in asthma and COPD have excluded patients with ACO. Because of the potential risk described in patients with asthma with the use of long-acting 2 agonist monotherapy, initial therapy for patients with ACO is recommended to include a long-acting bronchodilator in conjunction with inhaled corticosteroids. Long-acting muscarinic antagonists are effective in both asthma and COPD and should be considered in ACO as an add-on treatment. If inhaler therapy is not effective, advanced therapies based on phenotyping and identification of treatable traits may be considered.

CONCLUSION

Few studies have evaluated prospectively therapies in the ACO population, and future studies need to determine best strategies for the treatment of these patients, focusing on targeting its different phenotypes and its treatable traits.

The ethanol extract of Involcucrum castaneae ameliorated ovalbumin-induced airway inflammation and smooth muscle thickening in guinea pigs

ETHNOPHARMACOLOGICAL RELEVANCE

Involucrum castaneae(IC)is used in Chinese folk medicine to treat various lung diseases, as well as for its reducing phlegm and anti-inflammatory properties.

AIM OF THE STUDY

The purpose of this experiment is to verify the effect of IC on airway inflammation, responsiveness in ovalbumin (OVA)-induced asthmatic guinea pigs. The main chemical components of IC were also analyzed.

MATERIALS AND METHODS

The potential of the ethanol extract of Involucrum castaneae (EEIC) to protect against OVA-induced allergic airway response in guinea pigs was investigated. The latency of asthma in guinea pigs were recorded after the allergic asthma induced. Enzyme-linked immunosorbent assay (ELISA) was used to measure the levels of immunoglobulin E (IgE), interleukin-5 (IL-5), nerve growth factor (NGF) and interferon-γ (IFN-γ) in asthma allergy. Reverse transcription-PCR (RT-PCR) was used to detect the expression of IL-5 mRNA in asthmatic guinea pig lungs. Paraffin sections of lung tissue were used to analyze pathological changes. The total flavonoid content was determined and the chemical components were analyzed by LC-MS/MS.

RESULTS

It was found that EEIC was able to reduce the number of eosinophil (EOS) in bronchoalveolar lavage fluid (BALF) and peripheral blood (PB) in the guinea pig model of OVA -induced asthma. Meanwhile, it also significantly reduced the levels of inflammation-related factors IgE and IL-5, decreased the expression of IL-5 mRNA in lung tissue, and increased the level of IFN-γ. Pathological examination of paraffin section of lung tissue showed that EEIC can reduce the thickening of bronchial smooth muscle and reduce the infiltration damage of tissues by various inflammatory cells. The presence of flavonoids, terpenoids and phenolic compounds in EEIC might be responsible for these activities.

CONCLUSION

IC alleviated airway inflammation and smooth muscle thickening in guinea pigs with OVA-sensitized allergic asthma. The paper explains the traditional efficacy and material basis of IC and lays a foundation for further development.