Lysyl oxidase-like 2 is increased in asthma and contributes to asthmatic airway remodelling

Airway smooth muscle cells (ASM) are fundamental to asthma pathogenesis, influencing bronchoconstriction, airway hyper-responsiveness, and airway remodelling. Extracellular matrix (ECM) can influence tissue remodelling pathways, however, to date no study has investigated the effect of ASM ECM stiffness and crosslinking on the development of asthmatic airway remodelling. We hypothesised that TGFβ activation by ASM is influenced by ECM in asthma and sought to investigate the mechanisms involved. This study combines in vitro and in vivo approaches: human ASM cells were used in vitro to investigate basal TGFβ activation and expression of ECM crosslinking enzymes. Human bronchial biopsies from asthmatic and non-asthmatic donors were used to confirm LOXL2 expression ASM. A chronic ovalbumin model of asthma was used to study the effect of LOXL2 inhibition on airway remodelling. We found that ASM cells from asthmatics activated more TGFβ basally than non-asthmatic controls and that diseased cell-derived ECM influences levels of TGFβ activated. Our data demonstrate that the ECM crosslinking enzyme LOXL2 is increased in asthmatic ASM cells and in bronchial biopsies. Crucially, we show that LOXL2 inhibition reduces ECM stiffness and TGFβ activation in vitro, and can reduce subepithelial collagen deposition and ASM thickness, two features of airway remodelling, in an ovalbumin mouse model of asthma. These data are the first to highlight a role for LOXL2 in the development of asthmatic airway remodelling and suggest that LOXL2 inhibition warrants further investigation as a potential therapy to reduce remodelling of the airways in severe asthma.

Scopoletin inhibits PDGF-BB-induced proliferation and migration of airway smooth muscle cells by regulating NF-κκB signaling pathway

Background: Asthma is a common chronic inflammatory disease of the airway, and airway remodeling and the proliferation mechanism of airway smooth muscle cells (ASMCs) is of great significance to combat this disease.Objective: To assess possible effects of scopoletin on asthma and the potential signaling pathway.Materials and methods: ASMCs were treated PDGF-BB and scopoletin and subjected to cell viability detection by CCK-8 assay. Cell migration of ASMCs was determined by a wound closure assay and transwell assay. The protein level of MMP2, MMP9, calponin and α-SMA were measured using western blot. The levels of NF-κB signaling pathway were detected by Western blotting.Results: Scopoletin inhibited proliferation of PDGF-BB - induced ASMCs. Also it suppressed the migration and invasion of PDGF-BB - induced ASMCs. We further showed that Scopoletin regulated phenotypic transition of ASMCs. Mechanically, Scopoletin inhibited proliferation and invasion of ASMCs by regulating NF-κB signaling pathway.Conclusions: We therefore thought Scopoletin could serve as a promising drug for the treatment of asthma.

Curcumol inhibits PDGF-BB-induced proliferation and migration of airway smooth muscle cells by suppressing ERK/CREB pathway

Background: Curcumol, possessing antiviral, antifungal, antimicrobial, anticancer, and anti-inflammatory properties, has been widely used in treating cancers and liver fibrosis. The aim of this study was to determine the effect of curcumol on the progression of asthma.Materials and methods: Curcumol was administrated to platelet-derived growth factor (PDGF)- BB-stimulated airway smooth muscle cells (ASMCs). The proliferation of ASMCs was assessed by MTT and EdU incorporation assays. The apoptosis of ASMCs was measured by flow cytometry and Western blotting. The migration of ASMCs was evaluated by Transwell migration assay and Western blotting. The regulatory effects of curcumol on extracellular signal-regulated protein kinase (ERK)/cAMP response element-binding protein (CREB) pathway was evaluated by Western blotting.Results: The proliferation and migration of ASMCs induced by PDGF-BB was suppressed, and the apoptosis of ASMCs was elevated by curcumol in a dose-dependent manner. The activation of ERK/CREB pathway induced by PDGF-BB was suppressed by curcumol.Conclusion: Curcumol could suppress ERK/CREB pathway to inhibit proliferation and migration and promote apoptosis of PDGF-BB-stimulated ASMCs. These findings suggest that curcumol may act as a potential drug for asthma treatment.

Human Lung Mast Cells Impair Corticosteroid Responsiveness in Human Airway Smooth Muscle Cells

The mechanisms underlying corticosteroid insensitivity in severe asthma have not been elucidated although some indirect clinical evidence points toward a role of mast cells. Here, we tested the hypothesis that mast cells can drive corticosteroid insensitivity in airway smooth muscle cells, a key player in asthma pathogenesis. Conditioned media from resting or FcεR1-activated human lung mast cells were incubated with serum-deprived ASM cells (1:4 dilution, 24 h) to determine their impact on the anti-inflammatory action of fluticasone on ASM cell chemokine expression induced by TNFα (10 ng/ml). Conditioned media from FcεR1-activated mast cells (but not that from non-activated mast cells or control media) significantly reduced the ability of 100 nM fluticasone to suppress ASM TNFα-dependent CCL5 and CXCL10 production at both mRNA and protein levels. In contrast, fluticasone inhibition of CXCL-8 production by TNFα was still preserved in the presence of activated mast cell conditioned media. Transcriptomic analysis validated by individual qPCR assays revealed that activated mast cell conditioned media dramatically reduced the number of anti-inflammatory genes induced by fluticasone in ASM cells. Our study demonstrates for the first time that conditioned media from FcεR1-activated mast cells blunt the anti-inflammatory action of corticosteroids in ASM cells by altering their transactivation properties. Because infiltration of mast cells within the ASM bundles is a defining feature of asthma, mast cell-derived mediators may contribute to the glucocorticoid insensitivity present in severe asthma.

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

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

Novel Voltage-Gated Potassium Channel Signaling Pathway and Asthma utilizing Bronchoscopy Data

Asthma is a disease characterized by an excess of free-radical nitric oxide, NO, which leads to airway inflammation and obstruction. S-nitrosothiols (SNO’s) are an important regulator in NO signaling, helping to relieve oxidative stress as well as bronchodilate and relax airway smooth muscle cells. SNO’s exert most of their effects through the NO-cysteine interactions found particularly in S-nitrosocysteine (CSNO). The particular S-nitrosocysteine of interest in this paper is L-CSNO due to its ability to inhibit potassium channels associated with poor lung function, thereby improving ventilation in asthmatic patients. Potassium channels, amongst other ion channels as well, are a new target for therapeutic asthma treatment due to their ability to regulate vascular smooth muscle cells. KCN genes from bronchoscopy data from asthma and control patients were sequenced and analyzed against several measures for asthma and general lung function: asthma severity, FeNO, FEV1%, and androgen receptor gene expression. The goal of this study was to determine which KCN genes, and subsequent Kv channels, are associated with better lung function and which are associated with worse lung function/more severe asthma. The most beneficial KCN genes were found to be KCNA1 and KCNA4, whereas the KCN gene associated with the worst lung function was the KCNK6 gene family. Thus, a potential novel signaling pathway for asthma regulation may involve the binding of L-CSNO to the Kv channels encoded by the KCNK6 gene family in order to inactivate them and improve ventilation and overall lung function.