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BackgroundIdiopathic pulmonary fibrosis (IPF) is a common and invariably lethal interstitial lung disease with poorly effective therapy. Blockade of the K(+) channel KCa3.1 reduces constitutive α-SMA and Smad2/3 nuclear translocation in IPF-derived human lung myofibroblasts (HLMFs), and inhibits several transforming growth factor beta 1 (TGFβ1)-dependent cell processes. We hypothesized that KCa3.1-dependent cell processes also regulate the TGFβ1-dependent Smad2/3 signalling pathway in HLMFs. HLMFs obtained from non-fibrotic controls (NFC) and IPF lungs were grown in vitro and examined for αSMA expression by immunofluorescence, RT-PCR, and flow cytometry. Two specific and distinct KCa3.1 blockers (TRAM-34 200 nM and ICA-17043 [Senicapoc] 100 nM) were used to determine their effects on TGFβ1-dependent signalling. Expression of phosphorylated and total Smad2/3 following TGFβ1 stimulation was determined by Western blot and Smad2/3 nuclear translocation by immunofluorescence.ResultsKCa3.1 block attenuated TGFβ1-dependent Smad2/3 phosphorylation and nuclear translocation, and this was mimicked by lowering the extracellular Ca(2+) concentration. KCa3.1 block also inhibited Smad2/3-dependent gene transcription (αSMA, collagen type I), inhibited KCa3.1 mRNA expression, and attenuated TGFβ1-dependent αSMA protein expression.ConclusionsKCa3.1 activity regulates TGFβ1-dependent effects in NFC- and IPF-derived primary HLMFs through the regulation of the TGFβ1/Smad signalling pathway, with promotion of downstream gene transcription and protein expression. KCa3.1 blockers may offer a novel approach to treating IPF.

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.

Introduction: Idiopathic pulmonary fibrosis (IPF) is a progressive, fatal lung disease with a poor prognosis and increasing incidence. Pirfenidone and nintedanib are the only approved treatments for IPF but have limited efficacy and their mechanisms of action are poorly understood. Here we have examined the effects of pirfenidone and nintedanib in a human model of lung fibrogenesis, and compared these with the putative anti-fibrotic compounds Lipoxin A4 (LXA4), and senicapoc, a KCa3.1 ion channel blocker.Methods: Early fibrosis was induced in cultured human lung parenchyma using TGFβ1 for 7 days, ± pirfenidone, nintedanib, or LXA4. Pro-fibrotic responses were examined by RT-PCR, immunohistochemistry and soluble collagen secretion.Results: Thirty six out of eighty four IPF and fibrosis-associated genes tested were significantly upregulated by TGFβ1 in human lung parenchyma with a ≥0.5 log2FC (n = 32). Nintedanib (n = 13) reduced the mRNA expression of 14 fibrosis-associated genes including MMPs (MMP1,−4,−13,−14), integrin α2, CXCR4 and PDGFB, but upregulated α-smooth muscle actin (αSMA). Pirfenidone only reduced mRNA expression for MMP3 and −13. Senicapoc (n = 11) previously attenuated the expression of 28 fibrosis-associated genes, including αSMA, several growth factors, collagen type III, and αV/β6 integrins. Pirfenidone and nintedanib significantly inhibited TGFβ1-induced fibroblast proliferation within the tissue, but unlike senicapoc, neither pirfenidone nor nintedanib prevented increases in tissue αSMA expression. LXA4 was ineffective.Conclusions: Pirfenidone and nintedanib demonstrate modest anti-fibrotic effects and provide a benchmark for anti-fibrotic activity of new drugs in human lung tissue. Based on these data, we predict that the KCa3.1 blocker senicapoc will show greater benefit than either of these licensed drugs in IPF.

BackgroundIdiopathic pulmonary fibrosis is a common and invariably fatal disease with limited therapeutic options. Ca2+-activated KCa3.1 potassium channels play a key role in promoting TGFβ1 and bFGF-dependent profibrotic responses in human lung myofibroblasts (HLMFs). We hypothesised that KCa3.1 channel-dependent cell processes regulate HLMF αSMA expression via Smad2/3 signalling pathways.MethodsIn this study we have compared the phenotype of HLMFs derived from non-fibrotic healthy control lungs (NFC) with cells derived from IPF lungs. HLMFs grown in vitro were examined for αSMA expression by immunofluorescence (IF), RT-PCR and flow cytommetry. Basal Smad2/3 signalling was examined by RT-PCR, western blot and immunofluorescence. Two specific and distinct KCa3.1 blockers (TRAM-34 200 nM and ICA-17043 [Senicapoc] 100 nM) were used to determine their effects on HLMF differentiation and the Smad2/3 signalling pathways.ResultsIPF-derived HLMFs demonstrated increased constitutive expression of both α-smooth muscle actin (αSMA) and actin stress fibres, indicative of greater myofibroblast differentiation. This was associated with increased constitutive Smad2/3 mRNA and protein expression, and increased Smad2/3 nuclear localisation. The increased Smad2/3 nuclear localisation was inhibited by removing extracellular Ca2+ or blocking KCa3.1 ion channels with selective KCa3.1 blockers (TRAM-34, ICA-17043). This was accompanied by de-differentiation of IPF-derived HLMFs towards a quiescent fibroblast phenotype as demonstrated by reduced αSMA expression and reduced actin stress fibre formation.ConclusionsTaken together, these data suggest that Ca2+- and KCa3.1-dependent processes facilitate "constitutive" Smad2/3 signalling in IPF-derived fibroblasts, and thus promote fibroblast to myofibroblast differentiation. Importantly, inhibiting KCa3.1 channels reverses this process. Targeting KCa3.1 may therefore provide a novel and effective approach for the treatment of IPF and there is the potential for the rapid translation of KCa3.1-directed therapy to the clinic.

Inhaled corticosteroids (ICS) are the core component of asthma treatment and the only maintenance therapy known to prevent asthma death. There is currently no evidence that biologics prevent asthma death in people with asthma, and as such, biologics cannot be recommended as an alternative to ICS therapy. Taking the time to assess adherence and provide interventions and education to support patients in asthma self-management has been shown to improve patient outcomes. It is therefore our responsibility as healthcare professionals to ensure that patients are supported, educated and motivated to adhere to ICS therapy before progressing to biologic therapies.

Airway hyperresponsiveness (AHR) is a key clinical feature of asthma. The presence of AHR in people with asthma provides the substrate for bronchoconstriction in response to numerous diverse stimuli, contributing to airflow limitation and symptoms including breathlessness, wheeze, and chest tightness. Dysfunctional airway smooth muscle significantly contributes to AHR and is displayed as increased sensitivity to direct pharmacologic bronchoconstrictor stimuli, such as inhaled histamine and methacholine (direct AHR), or to endogenous mediators released by activated airway cells such as mast cells (indirect AHR). Research in in vivo human models has shown that the disrupted airway epithelium plays an important role in driving inflammation that mediates indirect AHR in asthma through the release of cytokines such as thymic stromal lymphopoietin and IL-33. These cytokines upregulate type 2 cytokines promoting airway eosinophilia and induce the release of bronchoconstrictor mediators from mast cells such as histamine, prostaglandin D 2 , and cysteinyl leukotrienes. While bronchoconstriction is largely due to airway smooth muscle contraction, airway structural changes known as remodeling, likely mediated in part by epithelial-derived mediators, also lead to airflow obstruction and may enhance AHR. In this review, we outline the current knowledge of the role of the airway epithelium in AHR in asthma and its implications on the wider disease. Increased understanding of airway epithelial biology may contribute to better treatment options, particularly in precision medicine. [ABSTRACT FROM AUTHOR]

Background: Idiopathic pulmonary fibrosis (IPF) is a common, progressive and invariably lethal interstitial lung disease with no effective therapy. We hypothesised that KCa3.1 K+ channel-dependent cell processes contribute to IPF pathophysiology. Methods: KCa3.1 expression in primary human lung myofibroblasts was examined using RT-PCR, western blot, immunofluorescence and patch-clamp electrophysiology. The role of KCa3.1 channels in myofibroblast proliferation, wound healing, collagen secretion and contraction was examined using two specific and distinct KCa3.1 blockers (TRAM-34 and ICA-17043 [Senicapoc]). Results: Both healthy non fibrotic control and IPF-derived human lung myofibroblasts expressed KCa3.1 channel mRNA and protein. KCa3.1 ion currents were elicited more frequently and were larger in IPF-derived myofibroblasts compared to controls. KCa3.1 currents were increased in myofibroblasts by TGFβ1 and basic FGF. KCa3.1 was expressed strongly in IPF tissue. KCa3.1 pharmacological blockade attenuated human myofibroblast proliferation, wound healing, collagen secretion and contractility in vitro, and this was associated with inhibition of TGFβ1-dependent increases in intracellular free Ca2+. Conclusions: KCa3.1 activity promotes pro-fibrotic human lung myofibroblast function. Blocking KCa3.1 may offer a novel approach to treating IPF with the potential for rapid translation to the clinic. © 2013 Roach et al.

BackgroundThe Ca(2+)-activated K(+) channel K(Ca)3.1 is expressed in several structural and inflammatory airway cell types and is proposed to play an important role in the pathophysiology of asthma. The aim of the current study was to determine whether inhibition of K(Ca)3.1 modifies experimental asthma in sheep.Methodology and principal findingsAtopic sheep were administered either 30 mg/kg Senicapoc (ICA-17073), a selective inhibitor of the K(Ca)3.1-channel, or vehicle alone (0.5% methylcellulose) twice daily (orally). Both groups received fortnightly aerosol challenges with house dust mite allergen for fourteen weeks. A separate sheep group received no allergen challenges or drug treatment. In the vehicle-control group, twelve weeks of allergen challenges resulted in a 60±19% increase in resting airway resistance, and this was completely attenuated by treatment with Senicapoc (0.25±12%; n = 10, P = 0.0147). The vehicle-control group had a peak-early phase increase in lung resistance of 82±21%, and this was reduced by 58% with Senicapoc treatment (24±14%; n = 10, P = 0.0288). Senicapoc-treated sheep also demonstrated reduced airway hyperresponsiveness, requiring a significantly higher dose of carbachol to increase resistance by 100% compared to allergen-challenged vehicle-control sheep (20±5 vs. 52±18 breath-units of carbachol; n = 10, P = 0.0340). Senicapoc also significantly reduced eosinophil numbers in bronchoalveolar lavage taken 48 hours post-allergen challenge, and reduced vascular remodelling.ConclusionsThese findings suggest that K(Ca)3.1-activity contributes to allergen-induced airway responses, inflammation and vascular remodelling in a sheep model of asthma, and that inhibition of K(Ca)3.1 may be an effective strategy for blocking allergen-induced airway inflammation and hyperresponsiveness in humans.

BackgroundEosinophilic airway inflammation is heterogeneous in asthmatic patients. We recently described a distinct subtype of asthma defined by the expression of genes inducible by T(H)2 cytokines in bronchial epithelium. This gene signature, which includes periostin, is present in approximately half of asthmatic patients and correlates with eosinophilic airway inflammation. However, identification of this subtype depends on invasive airway sampling, and hence noninvasive biomarkers of this phenotype are desirable.ObjectiveWe sought to identify systemic biomarkers of eosinophilic airway inflammation in asthmatic patients.MethodsWe measured fraction of exhaled nitric oxide (Feno), peripheral blood eosinophil, periostin, YKL-40, and IgE levels and compared these biomarkers with airway eosinophilia in asthmatic patients.ResultsWe collected sputum, performed bronchoscopy, and matched peripheral blood samples from 67 asthmatic patients who remained symptomatic despite maximal inhaled corticosteroid treatment (mean FEV(1), 60% of predicted value; mean Asthma Control Questionnaire [ACQ] score, 2.7). Serum periostin levels are significantly increased in asthmatic patients with evidence of eosinophilic airway inflammation relative to those with minimal eosinophilic airway inflammation. A logistic regression model, including sex, age, body mass index, IgE levels, blood eosinophil numbers, Feno levels, and serum periostin levels, in 59 patients with severe asthma showed that, of these indices, the serum periostin level was the single best predictor of airway eosinophilia (P = .007).ConclusionPeriostin is a systemic biomarker of airway eosinophilia in asthmatic patients and has potential utility in patient selection for emerging asthma therapeutics targeting T(H)2 inflammation.

Abstract Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease with limited therapeutic options. KCa3.1 ion channels play a critical role in TGFβ1-dependent pro-fibrotic responses in human lung myofibroblasts. We aimed to develop a human lung parenchymal model of fibrogenesis and test the efficacy of the selective KCa3.1 blocker senicapoc. 2 mm3 pieces of human lung parenchyma were cultured for 7 days in DMEM ± TGFβ1 (10 ng/ml) and pro-fibrotic pathways examined by RT-PCR, immunohistochemistry and collagen secretion. Following 7 days of culture with TGFβ1, 41 IPF- and fibrosis-associated genes were significantly upregulated. Immunohistochemical staining demonstrated increased expression of ECM proteins and fibroblast-specific protein after TGFβ1-stimulation. Collagen secretion was significantly increased following TGFβ1-stimulation. These pro-fibrotic responses were attenuated by senicapoc, but not by dexamethasone. This 7 day ex vivo model of human lung fibrogenesis recapitulates pro-fibrotic events evident in IPF and is sensitive to KCa3.1 channel inhibition. By maintaining the complex cell-cell and cell-matrix interactions of human tissue, and removing cross-species heterogeneity, this model may better predict drug efficacy in clinical trials and accelerate drug development in IPF. KCa3.1 channels are a promising target for the treatment of IPF.

Abstract Background Patients with difficult-to-control asthma consume 50–60% of healthcare costs attributed to asthma and cost approximately five-times more than patients with mild stable disease. Recent evidence demonstrates that not all patients with asthma have a typical type 2 (T2)-driven eosinophilic inflammation. These asthmatics have been called ‘T2-low asthma’ and have a minimal response to corticosteroid therapy. Adjustment of corticosteroid treatment using sputum eosinophil counts from induced sputum has demonstrated reduced severe exacerbation rates and optimized corticosteroid dose. However, it has been challenging to move induced sputum into the clinical setting. There is therefore a need to examine novel algorithms to target appropriate levels of corticosteroid treatment in difficult asthma, particularly in T2-low asthmatics. This study examines whether a composite non-invasive biomarker algorithm predicts exacerbation risk in patients with asthma on high-dose inhaled corticosteroids (ICS) (± long-acting beta agonist) treatment, and evaluates the utility of this composite score to facilitate personalized biomarker-specific titration of corticosteroid therapy. Methods/design Patients recruited to this pragmatic, multi-centre, single-blinded randomised controlled trial are randomly allocated into either a biomarker controlled treatment advisory algorithm or usual care group in a ratio of 4:1. The primary outcome measure is the proportion of patients with any reduction in ICS or oral corticosteroid dose from baseline to week 48. Secondary outcomes include the rate of protocol-defined severe exacerbations per patient per year, time to first severe exacerbation from randomisation, dose of inhaled steroid at the end of the study, cumulative dose of inhaled corticosteroid during the study, proportion of patients on oral corticosteroids at the end of the study, proportion of patients who decline to progress to oral corticosteroids despite composite biomarker score of 2, frequency of hospital admission for asthma, change in the 7-item Asthma Control Questionnaire (ACQ-7), Asthma Quality of Life Questionnaire (AQLQ), forced expiratory volume in 1 s (FEV1), exhaled nitric oxide, blood eosinophil count, and periostin levels from baseline to week 48. Blood will also be taken for whole blood gene expression; serum, plasma, and urine will be stored for validation of additional biomarkers. Discussion Multi-centre trials present numerous logistical issues that have been addressed to ensure minimal bias and robustness of study conduct. Trial registration ClinicalTrials.gov, NCT02717689 . Registered on 16 March 2016.

Background: Severe asthma exacerbations are costly to patients and the NHS, and occur frequently in severely allergic patients. Objective: To ascertain whether or not nocturnal temperature-controlled laminar airflow (TLA) device usage over 12 months can reduce severe exacerbations and improve asthma control and quality of life compared with a placebo device, while being cost-effective and acceptable to adults with severe allergic asthma. Design: A pragmatic, multicentre, randomised, double-blind, placebo-controlled, parallel-group, superiority trial with qualitative interviews. The trial included an internal pilot with qualitative focus groups. Setting: Fourteen hospitals in the UK that manage patients with severe asthma. Participants: Adults (16–75 years) with severe, poorly controlled, exacerbation-prone asthma despite high-intensity treatment, and who are sensitised to a perennial indoor aeroallergen. Intervention: Nocturnal, home-based TLA treatment using an Airsonett® (Airsonett AB, Ängelholm, Sweden) device. The comparator was a placebo device that was identical to the active device except that it did not deliver the laminar airflow. Participants were allocated 1 : 1 to TLA therapy or placebo, minimised by site, origin of case, baseline severe exacerbation frequency, maintenance oral corticosteroid use and pre-bronchodilator forced expiratory volume in 1 second. Main outcome measures: Primary outcome – frequency of severe asthma exacerbations occurring within the 12-month follow-up period, defined as worsening of asthma requiring systemic corticosteroids [≥ 30 mg of prednisolone or equivalent daily (or ≥ 50% increase in dose if on maintenance dose of ≥ 30 mg of prednisolone)] for ≥ 3 days. Secondary outcomes – changes in asthma control, lung function, asthma-specific and global quality of life for participants, adherence to the intervention, device acceptability, health-care resource use and cost-effectiveness. Results: Between May 2014 and January 2016, 489 patients consented to participate in the trial, of whom 249 failed screening and 240 were randomised (n = 119 in the treatment group and n = 121 in the placebo group); all were analysed. In total, 202 participants (84%) reported use of the device for 9–12 months. Qualitative analyses showed high levels of acceptability. The mean [standard deviation (SD)] rate of severe exacerbations did not differ between groups [active 1.39 (1.57), placebo 1.48 (2.03); risk ratio 0.92, 95% CI 0.66 to 1.27; p = 0.616]. There were no significant differences in secondary outcomes for lung function, except for a reduction in mean daily peak expiratory flow [mean (SD) difference 14.7 l/minute (7.35 l/minute), 95% CI 0.32 to 29.1 l/minute; p = 0.045) for those in the active device group. There were no differences in asthma control or airway inflammation and no serious harms related to the device. No significant difference between the groups in quality-adjusted life-years gained over 1 year was observed. In addition, there was no difference in generic or disease-specific health-related quality of life overall, although statistically significant higher quality of life at month 6 was observed. Increases in quality of life were not sufficient to offset the annual costs associated with use of the TLA device. Limitations: Missing outcome data could have resulted in an underestimation of exacerbations and rendered the study inconclusive. Conclusions: Within the limits of the data, no consistent benefits of the active device were demonstrated, and the differences observed were not sufficient to make the device cost-effective. The types of patients who may benefit from the TLA device, and the reasons for large reductions in exacerbation frequency in severe asthma trials, which also incorporate other methods of recording exacerbations, need to be explored. Trial registration: Current Controlled Trials ISRCTN46346208. Funding: This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 23, No. 29. See the NIHR Journals Library website for further project information.

Patients with type-2 (T2) cytokine-low severe asthma often have persistent symptoms despite suppression of T2 inflammation with corticosteroids. We sought to analyze whole blood transcriptome from 738 samples in T2-biomarker-high/-low patients with severe asthma to relate transcriptomic signatures to T2 biomarkers and asthma symptom scores. Bulk RNA-seq data were generated for blood samples (baseline, week 24, week 48) from 301 participants recruited to a randomized clinical trial of corticosteroid optimization in severe asthma. Unsupervised clustering, differential gene expression analysis, and pathway analysis were performed. Patients were grouped by T2-biomarker status and symptoms. Associations between clinical characteristics and differentially expressed genes (DEGs) associated with biomarker and symptom levels were investigated. Unsupervised clustering identified 2 clusters; cluster 2 patients were blood eosinophil-low/symptom-high and more likely to be receiving oral corticosteroids (OCSs). Differential gene expression analysis of these clusters, with and without stratification for OCSs, identified 2960 and 4162 DEGs, respectively. Six hundred twenty-seven of 2960 genes remained after adjusting for OCSs by subtracting OCS signature genes. Pathway analysis identified dolichyl-diphosphooligosaccharide biosynthesis and assembly of RNA polymerase I complex as significantly enriched pathways. No stable DEGs were associated with high symptoms in T2-biomarker-low patients, but numerous associated with elevated T2 biomarkers, including 15 that were upregulated at all time points irrespective of symptom level. OCSs have a considerable effect on whole blood transcriptome. Differential gene expression analysis demonstrates a clear T2-biomarker transcriptomic signature, but no signature was found in association with T2-biomarker-low patients, including those with a high symptom burden. [ABSTRACT FROM AUTHOR]

Although there is much circumstantial evidence implicating eosinophils as major orchestrators in the pathophysiology of asthma, recent studies have cast doubt on their importance. Not only does anti-interleukin-5 treatment not alter the course of the disease, but some patients with asthma do not have eosinophils in their airways, whereas patients with eosinophilic bronchitis exhibit a florid tissue eosinophilia but do not have asthma. In contrast, mast cells are found in all airways and localize specifically to key tissue structures such as the submucosal glands and airway smooth muscle within asthmatic bronchi, irrespective of disease severity or phenotype. Here they are activated and interact exclusively with these structural cells via adhesive pathways and through the release of soluble mediators acting across the distance of only a few microns. The location of mast cells within the airway smooth muscle bundles seems particularly important for the development and propagation of asthma, perhaps occurring in response to, and then serving to aggravate, an underlying abnormality in asthmatic airway smooth muscle function. Targeting this mast cell-airway smooth muscle interaction in asthma offers exciting prospects for the treatment of this common disease.

The KCa3.1 K+ channel has been proposed as a novel target for pulmonary diseases such as asthma and pulmonary fibrosis. It is expressed in epithelia but its expression and function in primary human bronchial epithelial cells (HBECs) has not been described. Due to its proposed roles in the regulation of cell proliferation, migration, and epithelial fluid secretion, inhibiting this channel might have either beneficial or adverse effects on HBEC function. The aim of this study was to assess whether primary HBECs express the KCa3.1 channel and its role in HBEC function. Primary HBECs from the airways of healthy and asthmatic subjects, SV-transformed BEAS-2B cells and the neoplastic H292 epithelial cell line were studied. Primary HBECs, BEAS-2B and H292 cells expressed KCa3.1 mRNA and protein, and robust KCa3.1 ion currents. KCa3.1 protein expression was increased in asthmatic compared to healthy airway epithelium in situ, and KCa3.1 currents were larger in asthmatic compared to healthy HBECs cultured in vitro. Selective KCa3.1 blockers (TRAM-34, ICA-17043) had no effect on epithelial cell proliferation, wound closure, ciliary beat frequency, or mucus secretion. However, several features of TGFβ1-dependent epithelial-mesenchymal transition (EMT) were inhibited by KCa3.1 blockade. Treatment with KCa3.1 blockers is likely to be safe with respect to airway epithelial biology, and may potentially inhibit airway remodelling through the inhibition of EMT.

CADM1 is a major receptor for the adhesion of mast cells (MCs) to fibroblasts, human airway smooth muscle cells (HASMCs) and neurons. It also regulates E-cadherin and alpha6beta4 integrin in other cell types. Here we investigated a role for CADM1 in MC adhesion to both cells and extracellular matrix (ECM). Downregulation of CADM1 in the human MC line HMC-1 resulted not only in reduced adhesion to HASMCs, but also reduced adhesion to their ECM. Time-course studies in the presence of EDTA to inhibit integrins demonstrated that CADM1 provided fast initial adhesion to HASMCs and assisted with slower adhesion to ECM. CADM1 downregulation, but not antibody-dependent CADM1 inhibition, reduced MC adhesion to ECM, suggesting indirect regulation of ECM adhesion. To investigate potential mechanisms, phosphotyrosine signalling and polymerisation of actin filaments, essential for integrin-mediated adhesion, were examined. Modulation of CADM1 expression positively correlated with surface KIT levels and polymerisation of cortical F-actin in HMC-1 cells. It also influenced phosphotyrosine signalling and KIT tyrosine autophosphorylation. CADM1 accounted for 46% of surface KIT levels and 31% of F-actin in HMC-1 cells. CADM1 downregulation resulted in elongation of cortical actin filaments in both HMC-1 cells and human lung MCs and increased cell rigidity of HMC-1 cells. Collectively these data suggest that CADM1 is a key adhesion receptor, which regulates MC net adhesion, both directly through CADM1-dependent adhesion, and indirectly through the regulation of other adhesion receptors. The latter is likely to occur via docking of KIT and polymerisation of cortical F-actin. Here we propose a stepwise model of adhesion with CADM1 as a driving force for net MC adhesion.

Mast cells (MCs) play a central role in the development of many diseases including asthma and pulmonary fibrosis. Interactions of human lung mast cells (HLMCs) with human airway smooth muscle cells (HASMCs) are partially dependent on adhesion mediated by cell adhesion molecule-1 (CADM1), but the adhesion mechanism through which HLMCs interact with human lung fibroblasts (HLFs) is not known. CADM1 is expressed as several isoforms (SP4, SP1, SP6) in HLMCs, with SP4 dominant. These isoforms differentially regulate HLMC homotypic adhesion and survival.In this study we have investigated the role of CADM1 isoforms in the adhesion of HLMCs and HMC-1 cells to primary HASMCs and HLFs.CADM1 overexpression or downregulation was achieved using adenoviral delivery of CADM1 short hairpin RNAs or isoform-specific cDNAs respectively.Downregulation of CADM1 attenuated both HLMC and HMC-1 adhesion to both primary HASMCs and HLFs. Overexpression of either SP1 or SP4 isoforms did not alter MC adhesion to HASMCs, whereas overexpression of SP4, but not SP1, significantly increased both HMC-1 cell and HLMC adhesion to HLFs. The expression level of CADM1 SP4 strongly predicted the extent of MC adhesion; linear regression indicated that CADM1 accounts for up to 67% and 32% of adhesion to HLFs for HMC-1 cells and HLMCs, respectively. HLFs supported HLMC proliferation and survival through a CADM1-dependent mechanism. With respect to CADM1 counter-receptor expression, HLFs expressed both CADM1 and nectin-3, whereas HASMCs expressed only nectin-3.Collectively these data indicate that the CADM1 SP4 isoform is a key receptor mediating human MC adhesion to HASMCs and HLFs. The differential expression of CADM1 counter-receptors on HLFs compared to HASMCs may allow the specific targeting of either HLMC-HLF or HLMC-HASMC interactions in the lung parenchyma and airways.

The influx of extracellular Ca(2+) into mast cells is critical for the FcεR1-dependent release of preformed granule-derived mediators and newly synthesised autacoids and cytokines. The Orai(CRACM) ion channel family provide the major pathway through which this Ca(2+) influx occurs. However the individual role of each of the three members of the Orai channel family in Ca(2+) influx and mediator release has not been defined in human mast cells.To assess whether there might be value in targeting individual Orai family members for the inhibition of FcεRI-dependent human lung mast cells (HLMC) mediator release.We used an adenoviral delivery system to transduce HLMCs with shRNAs targeted against Orai1 and Orai2 or with cDNAs directing the expression of dominant-negative mutations of the three known Orai channels.shRNA-mediated knockdown of Orai1 resulted in a significant reduction of approximately 50% in Ca(2+) influx and in the release of β-hexosaminidase (a marker of degranulation) and newly synthesized LTC4 in activated HLMCs. In contrast shRNA knockdown of Orai2 resulted in only marginal reductions of Ca(2+) influx, degranulation and LTC4 release. Transduced dominant-negative mutants of Orai1, -2 and -3 markedly reduced Orai currents and completely inhibited HLMC degranulation suggesting that Orai channels form heteromultimers in HLMCs, and that Orai channels comprise the dominant Ca(2+) influx pathway following FceRI-dependent HLMC activation. Inhibition of Orai currents did not alter HLMC survival. In addition we observed a significant down-regulation of the level of CRACM3 mRNA transcripts together with a small increase in the level of CRACM1 and CRACM2 transcripts following a period of sustained HLMC activation.Orai1 plays an important role in Ca(2+) influx and mediator release from HLMCs. Strategies which target Orai1 will effectively inhibit FcεRI-dependent HLMC activation, but spare off-target inhibition of Orai2 in other cells and body systems.

Idiopathic pulmonary fibrosis (IPF) is a common, progressive and invariably lethal interstitial lung disease with no effective therapy. We hypothesised that K(Ca)3.1 K(+) channel-dependent cell processes contribute to IPF pathophysiology.K(Ca)3.1 expression in primary human lung myofibroblasts was examined using RT-PCR, western blot, immunofluorescence and patch-clamp electrophysiology. The role of K(Ca)3.1 channels in myofibroblast proliferation, wound healing, collagen secretion and contraction was examined using two specific and distinct K(Ca)3.1 blockers (TRAM-34 and ICA-17043 [Senicapoc]).Both healthy non fibrotic control and IPF-derived human lung myofibroblasts expressed K(Ca)3.1 channel mRNA and protein. K(Ca)3.1 ion currents were elicited more frequently and were larger in IPF-derived myofibroblasts compared to controls. K(Ca)3.1 currents were increased in myofibroblasts by TGFβ1 and basic FGF. K(Ca)3.1 was expressed strongly in IPF tissue. K(Ca)3.1 pharmacological blockade attenuated human myofibroblast proliferation, wound healing, collagen secretion and contractility in vitro, and this was associated with inhibition of TGFβ1-dependent increases in intracellular free Ca(2+).K(Ca)3.1 activity promotes pro-fibrotic human lung myofibroblast function. Blocking K(Ca)3.1 may offer a novel approach to treating IPF with the potential for rapid translation to the clinic.

The Ca(2+)-activated K(+) channel K(Ca)3.1 is expressed in several structural and inflammatory airway cell types and is proposed to play an important role in the pathophysiology of asthma. The aim of the current study was to determine whether inhibition of K(Ca)3.1 modifies experimental asthma in sheep.Atopic sheep were administered either 30 mg/kg Senicapoc (ICA-17073), a selective inhibitor of the K(Ca)3.1-channel, or vehicle alone (0.5% methylcellulose) twice daily (orally). Both groups received fortnightly aerosol challenges with house dust mite allergen for fourteen weeks. A separate sheep group received no allergen challenges or drug treatment. In the vehicle-control group, twelve weeks of allergen challenges resulted in a 60±19% increase in resting airway resistance, and this was completely attenuated by treatment with Senicapoc (0.25±12%; n = 10, P = 0.0147). The vehicle-control group had a peak-early phase increase in lung resistance of 82±21%, and this was reduced by 58% with Senicapoc treatment (24±14%; n = 10, P = 0.0288). Senicapoc-treated sheep also demonstrated reduced airway hyperresponsiveness, requiring a significantly higher dose of carbachol to increase resistance by 100% compared to allergen-challenged vehicle-control sheep (20±5 vs. 52±18 breath-units of carbachol; n = 10, P = 0.0340). Senicapoc also significantly reduced eosinophil numbers in bronchoalveolar lavage taken 48 hours post-allergen challenge, and reduced vascular remodelling.These findings suggest that K(Ca)3.1-activity contributes to allergen-induced airway responses, inflammation and vascular remodelling in a sheep model of asthma, and that inhibition of K(Ca)3.1 may be an effective strategy for blocking allergen-induced airway inflammation and hyperresponsiveness in humans.

Chronic mast cell activation is a characteristic feature of asthma. BEAS-2B human airway epithelial cells (AEC) profoundly inhibit both constitutive and IgE-dependent human lung mast cell (HLMC) histamine release. The aim of this study was to examine the regulation of HLMC degranulation by primary AEC from healthy and asthmatic subjects, and investigate further the inhibitory mechanism.HLMC were co-cultured with both BEAS-2B and primary AEC grown as monolayers or air-liquid interface (ALI) cultures.Both constitutive and IgE-dependent HLMC histamine release were attenuated by BEAS-2B, primary AEC monolayers and ALI cultures. This occurred in the absence of HLMC-AEC contact indicating the presence of a soluble factor. Unlike healthy ALI AEC, asthmatic ALI-AEC did not significantly reduce constitutive histamine release. AEC inhibitory activity was transferable in primary AEC monolayer supernatant, but less active than with Transwell co-culture, suggesting that the inhibitory factor was labile. The AEC inhibitory effects were attenuated by both AEC wounding and pertussis toxin, indicating the involvement of a G(0)/G(i) receptor coupled mechanism. Solid phase extraction of lipids (

BACKGROUND: We have previously investigated the microlocalisation of M1 and M2 macrophages in NSCLC. This study investigated the non-macrophage (NM) expression of proteins associated with M1 and M2 macrophages in NSCLC. METHODS: Using immunohistochemistry, CD68(+) macrophages and proteins associated with either a cytotoxic M1 phenotype (HLA-DR, iNOS, and MRP 8/14), or a non-cytotoxic M2 phenotype (CD163 and VEGF) were identified. NM expression of the markers was analysed in the islets and stroma of surgically resected tumours from 20 patients with extended survival (ES) (median 92.7 months) and 20 patients with poor survival (PS) (median 7.7 months). RESULTS: The NM expression of NM-HLA-DR (p