Effects of aerobic exercise on molecular aspects of asthma: involvement of SOCS-JAK-STAT.

BACKGROUND: Aerobic training (AT) decreases airway inflammation in asthma, but the underlying cellular and molecular mechanisms are not completely understood. Thus, this study evaluated the participation of SOCS-JAK-STAT signaling in the effects of AT on airway inflammation, remodeling and hyperresponsiveness in a model of allergic airway inflammation. METHODS: C57Bl/6 mice were divided into Control (Co), Exercise (Ex), HDM (HDM), and HDM+Exercise (HDM+ Ex). Dermatophagoides pteronyssinus (100ug/mouse) were administered oro-tracheally on days 0, 7, 14, 21, 28, 35, 42 and 49. AT was performed in a treadmill during 4 weeks in moderate intensity, from day 24 until day 52. RESULTS: AT inhibited HDM-induced total cells (p<0.001), eosinophils (p<0.01), neutrophils (p<0.01) and lymphocytes (p<0.01) in BAL, and eosinophils (p<0.01), neutrophils (p<0.01) and lymphocytes (p<0.01) in peribronchial space. AT also reduced BAL levels of IL-4 (p<0.001), IL-5 (p<0.001), IL-13 (p<0.001), CXCL1 (p<0.01), IL-17 (p<0.01), IL-23 (p<0.05), IL-33 (p<0.05), while increased IL- 10 (p<0.05). Airway collagen fibers (p<0.01), elastic fibers p<0.01) and mucin (p<0.01) were also reduced by AT. AT also inhibited HDM-induced airway hyperresponsiveness (AHR) to methacholine 6,25mg/ml (p<0.01), 12,5mg/mL (p<0.01), 25mg/mL (p<0.01) and 50mg/mL (p<0.01). Mechanistically, AT reduced the expression of STAT6 (p<0.05), STAT3 (p<0.001), STAT5 (p<0.01) and JAK2 (p<0.001), similarly by peribronchial leukocytes and by airway epithelial cells. SOCS1 expression (p<0.001) was upregulated in leukocytes and in epithelial cells, SOCS2 (p<0.01) was upregulated in leukocytes and SOCS3 down-regulated in leukocytes (p<0.05) and in epithelial cells (p<0.001). CONCLUSIONS: AT reduces asthma phenotype involving SOCSJAK- STAT signaling.

Drugs Affecting TRP Channels.

Chronic obstructive pulmonary disease (COPD) and asthma are both common respiratory diseases that are associated with airflow reduction/obstruction and pulmonary inflammation. Whilst drug therapies offer adequate symptom control for many mild to moderate asthmatic patients, severe asthmatics and COPD patients symptoms are often not controlled, and in these cases, irreversible structural damage occurs with disease progression over time. Transient receptor potential (TRP) channels, in particular TRPV1, TRPA1, TRPV4 and TRPM8, have been implicated with roles in the regulation of inflammation and autonomic nervous control of the lungs. Evidence suggests that inflammation elevates levels of activators and sensitisers of TRP channels and additionally that TRP channel expression may be increased, resulting in excessive channel activation. The enhanced activity of these channels is thought to then play a key role in the propagation and maintenance of the inflammatory disease state and neuronal symptoms such as bronchoconstriction and cough. For TRPM8 the evidence is less clear, but as with TRPV1, TRPA1 and TRPV4, antagonists are being developed by multiple companies for indications including asthma and COPD, which will help in elucidating their role in respiratory disease.

Transient receptor potential (TRP) channels in the airway: role in airway disease.

Over the last few decades, there has been an explosion of scientific publications reporting the many and varied roles of transient receptor potential (TRP) ion channels in physiological and pathological systems throughout the body. The aim of this review is to summarize the existing literature on the role of TRP channels in the lungs and discuss what is known about their function under normal and diseased conditions. The review will focus mainly on the pathogenesis and symptoms of asthma and chronic obstructive pulmonary disease and the role of four members of the TRP family: TRPA1, TRPV1, TRPV4 and TRPM8. We hope that the article will help the reader understand the role of TRP channels in the normal airway and how their function may be changed in the context of respiratory disease.

Beta(2)-agonists block tussive responses in guinea pigs via an atypical cAMP-dependent pathway.

beta(2)-Adrenoceptor agonists are the most effective bronchodilators currently available, and are used for symptom management in asthmatics. However, whether beta(2)-agonists are also antitussive is controversial. Identifying an antitussive role for beta(2)-agonists and dissecting the possible mechanism of action may help to explain the inconsistencies in the clinical literature and lead to the development of novel therapeutic agents. The aim of the present study was to determine whether or not beta(2)-agonists attenuate the tussive response in guinea pig and human models, and, if so, to identify the mechanism(s) involved. Depolarisation of vagal sensory nerves (human and guinea pig) was assessed as an indicator of sensory nerve activity. Cough was measured in a conscious guinea pig model. A beta(2)-agonist, terbutaline, dose-dependently inhibited the cough response to tussive agents in conscious guinea pigs. Terbutaline and another beta(2)-agonist, fenoterol, blocked sensory nerve activation in vitro. Using these mechanistic models, it was established that beta(2)-agonists suppress the tussive response via a nonclassical cyclic adenosine monosphosphate-dependent pathway that involves the activation of protein kinase G and, subsequently, the opening of large-conductance calcium-activated potassium channels. In conclusion, beta(2)-adrenoceptor agonists are antitussive, and this property occurs due to a direct inhibition of sensory nerve activation. These findings may help to explain the confusion that exists in the clinical literature, and could be exploited to identify novel therapies for the treatment of cough, which is a significant unmet medical need.

House dust mite induces direct airway inflammation in vivo: implications for future disease therapy?

House dust mite (HDM) is the major source of allergen in house dust and is strongly associated with the development of asthma. HDM can evoke a direct, nonallergic inflammatory reaction in vitro. We aimed to determine whether this apparent nonallergic, inflammatory response can be observed in a more complex in vivo setting. Vehicle, Alum or HDM (Dermatophagoides pteronyssinus 5 microg, i.p. with Alum) sensitised Brown-Norway rats were challenged intratracheally with vehicle (saline), HDM (Der p 10 microg) or heat-inactivated HDM on day 21. Lung function changes and the associated inflammatory response were evaluated. Tissue and bronchoalveolar lavage from Alum sensitised Der p challenged animals exhibited strong eosinophilia and neutrophilia associated with an early release of pro-inflammatory cytokines (interleukin-13 and 1beta, eotaxin and thymus and activation-regulated chemokine). This response was not attenuated by removal of HDM-associated protease activity. Interestingly, the vehicle sensitised group (no Alum) lacked this inflammatory response. HDM allergen evokes nonallergic airways inflammation with an inflammatory profile similar to that of the asthmatic airway. This response, independent of the protease activity of the HDM extract, appeared to be linked to prior administration of the adjuvant Alum and the subsequent increase in total immunoglobulin E. This finding could have important implications in the development of future asthma therapies.

Cough sensors. III. Opioid and cannabinoid receptors on vagal sensory nerves.

Cough is a persistent symptom of many inflammatory airways' diseases. Cough is mediated by receptors sited on sensory nerves and then through vagal afferent pathways, which terminate in the brainstem respiratory centre. Cough is often described as an unmet clinical need. Opioids are the only prescription-based antitussives currently available in the UK. They possess limited efficacy and exhibit serious unwanted side effects, such as physical dependence, sedation, respiratory depression and gastrointestinal symptoms. There are three classical opioid receptors: the mu, kappa and delta receptors. Peripheral opioid receptors are sited on sensory nerves innervating the airways. A greater understanding of the role of the peripheral and centrally sited opioid receptors is necessary to allow the development of targeted treatments for cough. Because of the limited efficacy and the side-effect profile of the opioids, potential new treatments are sought to alleviate cough. One class of compounds that is currently under examination is the cannabinoids. Like the opioids, cannabinoids have peripheral and centrally sited receptors and also suffer from the blight of unwanted centrally mediated side effects such as sedation, cognitive dysfunction, tachycardia and psychotropic effects. Two cannabinoid receptors have been identified, the CB(1) and CB(2) receptors, and their distribution varies throughout the peripheral and central nervous system. Encouragingly, early studies with these compounds suggest that it may be possible to separate their antitussive activity from their centrally mediated side effects, with CB(2) agonists showing potential as putative new treatments for cough. In this chapter, we describe the opioid and cannabinoid receptors, their distribution and the effects they mediate. Moreover, we highlight their potential advantages and disadvantages in the treatment of cough.

Modulation of cholinergic contractions of airway smooth muscle by cathinone: potential beneficial effects in airway diseases.

Infusion of khat leaves is an African traditional remedy used to treat airway diseases. The beneficial effects of khat are thought to be due to the activity of its main active component, cathinone. Cathinone inhibited electric field stimulation-induced acetylcholine release and the contractions of smooth muscle, which could be responsible for the beneficial effects seen in airway disease. The mechanism of action of this natural product appears to be via the activation of both pre-junctional alpha(2) adrenergic and 5-hydroxytryptamine 7 receptors. The present novel study describes how cathinone modulates airway tone, and may go some way to explaining the traditional use of khat as a remedy for the alleviation of respiratory disease symptoms. In conclusion, cathinone may have beneficial effects in airway diseases with heightened cholinergic tone. There is some rationale for follow-up of these observations, given previous experience of other traditional remedies being developed for therapeutic use.

Inhibitory activity of the novel CB2 receptor agonist, GW833972A, on guinea-pig and human sensory nerve function in the airways.

BACKGROUND AND PURPOSE: Sensory nerves regulate central and local reflexes such as airway plasma protein leakage, bronchoconstriction and cough. Sensory nerve activity may be enhanced during inflammation such that these protective effects become exacerbated and deleterious. Cannabinoids are known to inhibit airway sensory nerve function. However, there is still controversy surrounding which receptor is involved in eliciting these effects. EXPERIMENTAL APPROACH: We have adopted a pharmacological approach, including using a novel, more selective CB(2) receptor agonist, GW 833972A (1000-fold selective CB(2)/CB(1)), and receptor selective antagonists to investigate the inhibitory activity of cannabinoids on sensory nerve activity in vitro and in vivo in guinea-pig models of cough and plasma extravasation. KEY RESULTS: GW 833972A inhibited capsaicin-induced depolarization of the human and guinea-pig and prostaglandin E(2) (PGE(2)) and hypertonic saline-induced depolarization of the guinea-pig isolated vagus nerve in vitro. GW 833972A also inhibited citric acid-induced cough but not plasma extravasation in the guinea-pig and this effect was blocked by a CB(2) receptor antagonist. CONCLUSIONS AND IMPLICATIONS: This confirms and extends previous studies highlighting the role of CB(2) receptors in the modulation of sensory nerve activity elicited both by the exogenous ligands capsaicin and hypertonic saline but also by endogenous modulators such as PGE(2) and low pH stimuli. These data establish the CB(2) receptor as an interesting target for the treatment of chronic cough.

Utility of exhaled nitric oxide as a noninvasive biomarker of lung inflammation in a disease model.

There is a great deal of interest in developing less invasive markers for monitoring airway inflammation and the effect of possible novel anti-inflammatory therapies that may take time to impact on disease pathology. Exhaled nitric oxide (eNO) has been shown to be a reproducible, noninvasive indicator of the inflammatory status of the airway in the clinic. The aim of the present study was to determine the usefulness of measuring eNO as a marker of the anti-inflammatory impact of glucocorticoid and an inhibitor of kappaB kinase-2 (IKK-2) inhibitor 2-[(aminocarbonyl)amino]-5-(4-fluorophenyl)-3-thiophenecarboxamide (TPCA-1), in a pre-clinical model of airway inflammation. Rats were given vehicle, budesonide or TPCA-1 prior to exposure to lipopolysaccharide, previously shown to induce an increase in eNO and airway neutrophilia/eosinophilia. Comparison of the effect of the two compounds on inflammatory components demonstrated a significant correlation between the impact on eNO and inflammatory cell burden in the airway. The current study demonstrates the usefulness of profiling potential disease-modifying therapies on exhaled nitric oxide levels and the way in which an effect on this noninvasive biomarker relates to effects on pathological parameters such as lung cellularity. Information from studies such as the current one would suggest that the measurement of exhaled nitric oxide has potential for monitoring inflammatory status in lung tissue.

Resveratrol, an extract of red wine, inhibits lipopolysaccharide induced airway neutrophilia and inflammatory mediators through an NF-kappaB-independent mechanism.

Consumption of a naturally occurring polyphenol, resveratrol, in particular through drinking moderate amounts of red wine, has been suggested to be beneficial to health. A plethora of in vitro studies published demonstrate various anti-inflammatory actions of resveratrol. The aim of this research was to determine whether any of these anti-inflammatory effects translate in vivo in a rodent model of LPS induced airway inflammation. Resveratrol reduced lung tissue neutrophilia to a similar magnitude as that achieved by treatment with budesonide. This was associated with a reduction in pro-inflammatory cytokines and prostanoid levels. Interestingly, the reduction did not appear to be due to an impact on NF-kappaB activation or the expression of the respective genes as suggested by various in vitro publications. These results suggest that resveratrol may possess anti-inflammatory properties via a novel mechanism. Elucidation of this mechanism may lead to potential new therapies for the treatment of chronic inflammation.

PPAR-gamma agonists as therapy for diseases involving airway neutrophilia.

Peroxisome proliferator-activated receptors (PPARs) are a family of ligand-activated nuclear hormone receptors belonging to the steroid receptor super-family. Previously, the present authors have shown that PPAR-gamma agonists inhibit the release of inflammatory cell survival factors and induce apoptosis in vitro. The aim of this study was to determine the effect of two structurally different PPAR agonists in an in vivo model of lipopolysaccharide (LPS)-induced airway inflammation. Mice were treated with PPAR agonists, rosiglitazone or SB 219994, prior to exposure to aerosolised LPS, and the extent of airway inflammation was assessed 3 h later. In these experiments, the PPAR ligands inhibited LPS-induced airway neutrophilia and associated chemoattractants/survival factors (keratinocyte-derived chemokine and granulocyte-colony stimulating factor) in the mouse lung. The present authors postulate that if a peroxisome proliferator-activated receptor agonist has the same effect in man, and neutrophils are important in the progression of respiratory diseases, such as chronic obstructive pulmonary disease, then this class of compounds could be a potential therapy. Furthermore, several peroxisome proliferator-activated receptor-gamma agonists have been shown to be clinically effective for the treatment of type II diabetes, suggesting that any benefit of peroxisome proliferator-activated receptor-gamma ligands in the progression of respiratory diseases, which may involve airway neutrophilia, could be explored relatively quickly.

Cough. 7: Current and future drugs for the treatment of chronic cough.

There are currently no effective treatments for controlling the cough response with an acceptable therapeutic ratio. However, several new mechanisms have been identified which may lead to the development of new drugs.

The role of matrix metalloproteinases (MMPs) in the pathophysiology of chronic obstructive pulmonary disease (COPD): a therapeutic role for inhibitors of MMPs?

Chronic obstructive pulmonary disease (COPD) is the collective term describing two separate chronic lung disease diseases: emphysema and chronic bronchitis (1). Initial clinical symptoms are shortness of breath and occasional cough. As the disease progresses difficulties in breathing becomes more pronounced, the cough more persistent and becomes associated with production of a clear sputum. In severe cases there are additional heart complications. The major risk factor for COPD is cigarette smoking. Between 1980 and 1990 there was a 22% increase in the occurrence of the disease with attributed 84,000 deaths in 1990 in the USA (www.nhlbi.nih.gov/health). Current therapies address the symptoms and range from bronchodilators, corticosteroids to oxygen. While there are no effective cures, although the disease can be prevented and progress slowed in many cases by removing the principal risk factor: cigarette smoking. Progression of the disease is associated with degradation of elastin in the walls of the alveoli, resulting in the functional destruction of the these organs. The net increase in proteolytic activity leading to this loss of alveoli function is a growing focus of pharmaceutical efforts for identification of a therapy for the amelioration of this disease. Of specific interest for this review has been the potential roles of members of the MMP family in both the destruction of elastin and the aberrant remodeling of damaged alveoli. An example of such a MMP is Metalloelastase. Metalloelastase (MMP-12) is (as the name suggests) capable of degrading elastin, as well as other extra-cellular matrix components. It is produced predominantly by infiltrating macrophages and appears essential for macrophage migration through extra-cellular matrix (2). Mouse metalloelastase knock-out studies implicate this enzyme as a key mediator in the pathology associated with cigarette smoke induced emhysema (3). There is also associative evidence from human genetic and animal studies suggesting a pathological link with other MMPs, such as MMPs 1,2,3,8 & 9. The evidence for the role of these MMPs in the pathological processes associated with COPD and prospects for MMP inhibitors as the basis for future therapies will be addressed in this review.

The protective role of epithelium-derived nitric oxide in isolated bovine trachea.

Airway epithelial cells from bovine airways can release relaxant factors such as nitric oxide (NO) and prostaglandin E(2) and the removal of airway epithelium results in an increased responsiveness of smooth muscle to spasmogen stimuli. In this study, we assessed whether or not epithelial NO modulates the contractile response of bovine trachea in vitro.Cumulative concentration-response curves to acetylcholine (ACh), histamine (Hist) and 5-hydroxytryptamine (5-HT) were obtained in both intact and epithelium denuded tracheal strips in the presence of indomethacin (10 microM).In intact, but not in epithelium denuded strips, preincubation with the NO synthase inhibitor L-N((G))-Nitro-arginine methyl ester (L-NAME), but not with D-NAME, shifted to the left the concentration-response curve to ACh (pD(2) values in the absence and in the presence of L-NAME were 3.47+/-0.1 and 4.60+/-0.1, respectively; P<0.05) and to Hist (pD(2) in the absence and in the presence of L-NAME: 3.89+/-0.1 and 4.54+/-0.1, respectively; P<0.05). This effect was reversed by L-arginine (1mM), but not by D-arginine. The contractile response to 5-HT was not affected by L-NAME in either intact or epithelium denuded strips. These data suggest that NO is an epithelial relaxant factor modulating airway cholinergic and histaminergic contraction of bovine trachea and that the activation of the epithelial NO synthase is a mediator-specific process.

High levels of nitric oxide synthase activity are associated with nasal polyp tissue from aspirin-sensitive asthmatics.

The pathogenesis of aspirin intolerance remains unclear. Inducible nitric oxide synthase (iNOS) expression is upregulated in nasal polyp epithelium, implying a role for nitric oxide (NO) in its formation. We decided to compare iNOS activity in polyp tissue from patients with and without aspirin intolerance. Nasal polyp tissue was collected from 15 patients undergoing routine nasal polypectomy. These patients were classified into three groups: Group A comprised patients with nasal polyps without asthma; Group B contained patients with nasal polyps and asthma; and Group C comprised patients with nasal polyps, asthma and aspirin sensitivity. All subjects in Group C had a history of aspirin-induced reaction and a confirmatory intranasal challenge with lysine-aspirin. NOS activity was measured by the ability of tissue homogenates to convert 3,4-L-arginine to L-citrulline in an L-N(G)-nitro-L-arginine-inhibitable fashion. The iNOS activity (picomoles) in polyp tissue from the 3 groups was: A, 248.72+/-220.79; B, 23.71+/-41.06; and C, 549.71+/-132.11. Thus, nasal polyps from patients with Samter's triad had a significantly higher iNOS activity (p = 0.004; one-way ANOVA). This finding does not correlate simply with disease severity or with the occurrence of asthma and could indicate another important facet of aspirin-induced airways disease.

The heterotopic tracheal allograft as an animal model of obliterative bronchiolitis.

Heterotopic tracheal allografts in small rodents have been shown to share many characteristics with the development of obliterative bronchiolitis (OB) in the clinic and therefore provide a suitable animal model for the study of OB. The model facilitates the examination of the pathogenesis of the disease and the elucidation of the cellular and molecular mechanisms involved in its development. The model provides a less technically demanding alternative to whole lung transplantation in small rodents and should lead to a speedier identification of new treatments that might prevent the development of post-transplantation OB in the clinic.

Evidence that the anti-spasmogenic effect of the beta-adrenoceptor agonist, isoprenaline, on guinea-pig trachealis is not mediated by cyclic AMP-dependent protein kinase.

1. The spasmolytic and anti-spasmogenic activity of beta-adrenoceptor agonists on airways smooth muscle is thought to involve activation of the cyclic AMP/cyclic AMP-dependent protein kinase (PKA) cascade. Here we have tested the hypothesis that PKA mediates the anti-spasmogenic activity of isoprenaline and other cyclic AMP-elevating agents in guinea-pig isolated trachea by utilizing a number of cell permeant cyclic AMP analogues that act as competitive 'antagonists' of PKA. 2. Anion-exchange chromatography of guinea-pig tracheae resolved two peaks of PKA activity that corresponded to the type I ( approximately 5%) and type II ( approximately 93%) isoenzymes. 3. Pre-treatment of tracheae with zardaverine (30 microM), vasoactive intestinal peptide (VIP) (1 microM) and the non-selective activator of PKA, Sp-8-CPT-cAMPS (10 microM), produced a non-parallel rightwards shift in the concentration-response curves that described acetylcholine (ACh)-induced tension generation. The type II-selective PKA inhibitor, Rp-8-CPT-cAMPS (300 microM), abolished this effect. 4. Pre-treatment of tracheae with Sp-8-Br-PET-cGMPS (30 microM) produced a non-parallel rightwards shift of the concentration-response curves that described ACh-induced tension generation. The selective cyclic GMP-dependent protein kinase (PKG) inhibitor, Rp-8-pCPT-cGMPS (300 microM), abolished this effect. 5. Pre-treatment of tracheae with isoprenaline (1 microM) produced a 10 fold shift to the right of the ACh concentration-response curve by a mechanism that was unaffected by Rp-8-Br-cAMPS (300 microM, selective inhibitor of type I PKA), Rp-8-CPT-cAMPS (300 microM) and Rp-8-pCPT-cGMPS (300 microM). 6. We conclude that the anti-spasmogenic activity of Sp-8-CPT-cAMPS, zardaverine and VIP in guinea-pig trachea is attributable to activation of the cyclic AMP/PKA cascade whereas isoprenaline suppresses ACh-induced contractions by a mechanism(s) that is independent of PKA and PKG.

Release of nerve growth factor by human pulmonary epithelial cells: role in airway inflammatory diseases.

Elevated levels of nerve growth factor (NGF) have been detected in the bronchoalveolar lavage fluid of patients with asthma. However, the source of this enhanced mediator production is not known. Here, we investigate the production of NGF from a human airway epithelial cell line (A549). Under basal conditions, A549 cells generated NGF in a time-dependent fashion. However, basal release was significantly augmented in a concentration-dependent manner in cells treated with interleukin-1beta (IL-1beta) or tumour necrosis factor-alpha (TNF-alpha) and inhibited by dexamethasone. These data suggest that NGF released from structural cells may be an important target for the anti-inflammatory effects of steroids in asthma therapy.