Pharmacology and Therapeutics of Bronchodilators Revisited.

Bronchodilators remain the cornerstone of the treatment of airway disorders such as asthma and chronic obstructive pulmonary disease (COPD). There is therefore considerable interest in understanding how to optimize the use of our existing classes of bronchodilator and in identifying novel classes of bronchodilator drugs. However, new classes of bronchodilator have proved challenging to develop because many of these have no better efficacy than existing classes of bronchodilator and often have unacceptable safety profiles. Recent research has shown that optimization of bronchodilation occurs when both arms of the autonomic nervous system are affected through antagonism of muscarinic receptors to reduce the influence of parasympathetic innervation of the lung and through stimulation of ß 2-adrenoceptors (ß 2-ARs) on airway smooth muscle with ß 2-AR-selective agonists to mimic the sympathetic influence on the lung. This is currently achieved by use of fixed-dose combinations of inhaled long-acting ß 2-adrenoceptor agonists (LABAs) and long-acting muscarinic acetylcholine receptor antagonists (LAMAs). Due to the distinct mechanisms of action of LAMAs and LABAs, the additive/synergistic effects of using these drug classes together has been extensively investigated. More recently, so-called "triple inhalers" containing fixed-dose combinations of both classes of bronchodilator (dual bronchodilation) and an inhaled corticosteroid in the same inhaler have been developed. Furthermore, a number of so-called "bifunctional drugs" having two different primary pharmacological actions in the same molecule are under development. This review discusses recent advancements in knowledge on bronchodilators and bifunctional drugs for the treatment of asthma and COPD. SIGNIFICANCE STATEMENT: Since our last review in 2012, there has been considerable research to identify novel classes of bronchodilator drugs, to further understand how to optimize the use of the existing classes of bronchodilator, and to better understand the role of bifunctional drugs in the treatment of asthma and chronic obstructive pulmonary disease.

The small quinolone derived compound HT61 enhances the effect of tobramycin against Pseudomonas aeruginosa in vitro and in vivo.

HT61 is a small quinolone-derived compound previously demonstrated to exhibit bactericidal activity against gram-positive bacteria including methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA). When combined with the classical antibiotics and antiseptics neomycin, gentamicin, mupirocin and chlorhexidine, HT61 demonstrated synergistic bactericidal activity against both MSSA and MRSA infections in vitro. In this study, we investigated the individual antimicrobial activity of HT61 alongside its capability to potentiate the efficacy of tobramycin against both a tobramycin sensitive laboratory reference strain (PAO1) and tobramycin resistant clinical isolates (RP73, NN2) of the gram-negative bacteria Pseudomonas aeruginosa (P. aeruginosa). Using broth microdilution methods, the MICs of HT61 were assessed against all strains, as well as the effect of HT61 in combination with tobramycin using both the chequerboard method and bacterial time-kill assays. A murine model of pulmonary infection was also used to evaluate the combination therapy of tobramycin and HT61 in vivo. In these studies, we demonstrated significant synergism between HT61 and tobramycin against the tobramycin resistant P. aeruginosa strains RP73 and NN2, whilst an additive/intermediate effect was observed for P. aeruginosa strain PA01 which was further confirmed using bacterial time kill analysis. In addition, the enhancement of tobramycin by HT61 was also evident in in vitro assays of biofilm eradication. Finally, in vivo studies revealed analogous effects to those observed in vitro with HT61 significantly reducing bacterial load when administered in combination with tobramycin against each of the three P. aeruginosa strains at the highest tested dose (10 mg/kg).

Use of animal models in IPF research.

Idiopathic pulmonary fibrosis (IPF) is a fatal interstitial lung disease with a poor prognosis and limited treatment options. Many compounds have shown efficacy in preclinical models of this condition, but only pirfenidone and nintedanib have been approved for clinical use. It is widely accepted that the current animal models of IPF need to be improved and in this review we have critically evaluated the current state of play of preclinical models of IPF and discuss the challenges facing this field. The popular model of a single intratracheal (I.T.) administration of bleomycin could be adapted to provide a more progressive fibrosis as is thought to occur in humans. Furthermore, currently the majority of new drugs are investigated in preclinical models of IPF are dosed using a prophylactic dosing regimen, whereas patients are almost always treated after the fibrosis is well established. Using a therapeutic dosing regimen in preclinical models would be a better way to establish potential efficacy of new drugs. The most popular endpoints examined in pre-clinical models of IPF are histological scoring and lung collagen content. However in IPF patients imaging and lung function tests are more commonly used as end points. We propose that examining more clinically relevant endpoints in pre-clinical models could also provide give a better indication of a compound's potential efficacy on endpoints measured in patients.

Mast cell glycosaminoglycans.

Mast cells contain granules packed with a mixture of proteins that are released on degranulation. The proteoglycan serglycin carries an array of glycosaminoglycan (GAG) side chains, sometimes heparin, sometimes chondroitin or dermatan sulphate. Tight packing of granule proteins is dependent on the presence of serglycin carrying these GAGs. The GAGs of mast cells were most intensively studied in the 1970s and 1980s, and though something is known about the fine structure of chondroitin sulphate and dermatan sulphate in mast cells, little is understood about the composition of the heparin/heparan sulphate chains. Recent emphasis on the analysis of mast cell heparin from different species and tissues, arising from the use of this GAG in medicine, lead to the question of whether variations within heparin structures between mast cell populations are as significant as variations in the mix of chondroitins and heparins.

Lipopolysaccharide (LPS) induced pulmonary neutrophil recruitment and platelet activation is mediated via the P2Y1 and P2Y14 receptors in mice.

Platelet activation occurs during host defence and in various inflammatory disorders. In animal models of infection and inflammation, experimental depletion of platelets leads to significantly reduced leukocyte recruitment and impaired clearance of pathogens from the lung. It is now appreciated that purinergic receptor activation is required for leukocyte activation, motility and adhesion, and platelet interactions with leukocytes can be modulated by purinergic stimulation of platelets. Here, we have investigated the role of platelet P2Y1, P2Y12, P2Y14, and P2X1 receptors on leukocyte recruitment and chemotaxis. Mice were administered either vehicle controls or selective P2Y1, P2Y12, P2Y14, or P2X1 antagonists intravenously before intranasal administration of lipopolysaccharide (LPS) to investigate the effect of these drugs on pulmonary leukocyte recruitment, peripheral platelet counts, bleeding times, and ex vivo platelet aggregation. Separately, platelets were incubated with P2Y1, P2Y12, P2X1 antagonists, or P2Y14 agonists to assess effects on platelet-induced neutrophil chemotaxis in vitro. Pulmonary neutrophil recruitment induced by intranasal LPS administration was inhibited in mice administered either with P2Y1 or P2Y14 antagonists, but not with P2Y12 or P2X1 antagonists. Furthermore, the administration of either a P2Y1 or a P2Y14 antagonist reversed the incidence of peripheral thrombocytopaenia associated with LPS exposure. Bleeding times were significantly increased in mice administered P2Y1, P2Y12, or P2X1 antagonists, whilst ex vivo platelet aggregation to ADP was significantly reduced. These haemostatic responses remained unaltered following antagonism of P2Y14. In vitro chemotaxis assays revealed direct antagonism of platelet P2Y1, but not P2Y12 or P2X1 receptors suppressed platelet-dependent neutrophil motility towards Macrophage derived chemokine (MDC, CCL22). Furthermore, the stimulation of platelets with selective P2Y14 agonists (UDP-glucose, MRS2690) resulted in significant platelet-dependent neutrophil chemotaxis. These results reveal a role for P2Y1 and P2Y14 activation of platelets following exposure to LPS, whilst haemostatic indices were unaffected by inhibition of platelet function with the P2Y14 antagonist in response to LPS.

Xanthines and Phosphodiesterase Inhibitors.

Theophylline is an orally acting xanthine that has been used since 1937 for the treatment of respiratory diseases including asthma and chronic obstructive pulmonary disease (COPD). However, in most treatment guidelines, xanthines have now been consigned to third-line therapy because of their narrow therapeutic window and propensity for drug-drug interactions. However, lower than conventional doses of theophylline considered to be bronchodilator are now known to have anti-inflammatory actions of relevance to the treatment of respiratory disease. The molecular mechanism(s) of action of theophylline are not well understood, but several potential targets have been suggested including non-selective inhibition of phosphodiesterases (PDE), inhibition of phosphoinositide 3-kinase, adenosine receptor antagonism and increased activity of certain histone deacetylases. Although theophylline has a narrow therapeutic window, other xanthines are in clinical use that are claimed to have a better tolerability such as doxofylline and bamifylline. Nonetheless, xanthines still play an important role in the treatment of asthma and COPD as they can show clinical benefit in patients who are refractory to glucocorticosteroid therapy, and withdrawal of xanthines from patients causes worsening of disease, even in patients taking concomitant glucocorticosteroids.More recently the orally active selective PDE4 inhibitor, roflumilast, has been introduced into clinical practice for the treatment of severe COPD on top of gold standard treatment. This drug has been shown to improve lung function in patients with severe COPD and to reduce exacerbations, but is dose limited by a range side effect, particularly gastrointestinal side effects.

Antitussive drugs--past, present, and future.

Cough remains a serious unmet clinical problem, both as a symptom of a range of other conditions such as asthma, chronic obstructive pulmonary disease, gastroesophageal reflux, and as a problem in its own right in patients with chronic cough of unknown origin. This article reviews our current understanding of the pathogenesis of cough and the hypertussive state characterizing a number of diseases as well as reviewing the evidence for the different classes of antitussive drug currently in clinical use. For completeness, the review also discusses a number of major drug classes often clinically used to treat cough but that are not generally classified as antitussive drugs. We also reviewed a number of drug classes in various stages of development as antitussive drugs. Perhaps surprising for drugs used to treat such a common symptom, there is a paucity of well-controlled clinical studies documenting evidence for the use of many of the drug classes in use today, particularly those available over the counter. Nonetheless, there has been a considerable increase in our understanding of the cough reflex over the last decade that has led to a number of promising new targets for antitussive drugs being identified and thus giving some hope of new drugs being available in the not too distant future for the treatment of this often debilitating symptom.

Bradykinin and capsaicin induced airways obstruction in the guinea pig are platelet dependent.

INTRODUCTION: Airways obstruction induced by intravenously administered bradykinin is abolished in guinea pigs treated with indomethacin, which has been shown to be, at least in part thromboxane dependent. As thromboxane is primarily generated from circulating platelets, we investigated whether airways obstruction induced by bradykinin, and other spasmogens, is platelet dependent and the role platelet aggregation played in this response. METHODS: Guinea pigs were chronically treated with busulfan to induce thrombocytopenia. Total lung resistance was measured in anaesthetised and mechanically ventilated control and thrombocytopaenic animals to various stimuli that induce airways obstruction. In other experiments, platelet aggregation was assessed in vitro in response to the same stimuli: guinea pigs were anaesthetized, blood was collected and centrifuged to generate firstly platelet-rich plasma and then platelet-poor plasma. Platelets were resuspended in HEPES buffer and platelet aggregation was assessed. RESULTS: Busulfan treatment significantly reduced the number of circulating platelets in guinea-pigs by 85.5%, but had no significant effect on the number of circulating leukocytes. Treatment with busulfan had no significant effect on bronchoconstriction induced by the direct acting spasmogens histamine or methacholine. However, platelet depletion significantly increased airways obstruction induced by Substance P, but caused a significant reduction in airways obstruction induced by bradykinin, bombesin or capsaicin (P < 0.05). None of these stimuli however were able to exhibit a direct effect on platelet aggregation in vitro. Moreover, busulfan did not significantly alter the contractility of guinea-pig isolated trachea in response to capsaicin. CONCLUSION: Airways obstruction induced by bombesin, capsaicin and bradykinin is platelet dependent, but not secondary to platelet aggregation.

A role for mitogen kinase kinase 3 in pulmonary inflammation validated from a proteomic approach.

Proteomics is a powerful tool to ascertain which proteins are differentially expressed in the context of disease. We have used this approach on inflammatory cells obtained from patients with asthma to ascertain whether novel drugs targets could be illuminated and to investigate the role of any such target in a range of in vitro and in vivo models of inflammation. A proteomic study was undertaken using peripheral blood mononuclear cells from mild asthmatic subjects compared with healthy subjects. The analysis revealed an increased expression of the intracellular kinase, mitogen activated protein kinase (MKK3), and the function of this protein was investigated further in preclinical models of inflammation using MKK3 knockout mice. We describe a 3.65 fold increase in the expression of MKK3 in CD8(+) T lymphocytes obtained from subjects with asthma compared with healthy subjects using a proteomic approach which we have confirmed in CD8(+), but not in CD4(+) T lymphocytes or human bronchial epithelial cells from asthmatic patients using a Western blot technique. In wild type mice, bacterial lipopolysaccharide (LPS) caused a significant increase in MKK3 expression and significantly reduced airway neutrophilia in MKK3(-/-) mice (median, 25, 75% percentile; wild/LPS; 5.3 (0.7-9.9) × 10(5) cells/mL vs MKK3(-/-)/LPS; 0 (0-1.9) × 10(5) cells/mL, P < 0.05). In contrast, eosinophilia in sensitized wild type mice challenged with allergen (0.5 (0.16-0.65) × 10(5) cells/mL) was significantly increased in MKK3(-/-) mice (2.2 (0.9-3.5) × 10(5) cells/mL, P < 0.05). Our results suggest that asthma is associated with MKK3 over-expression in CD8(+) cells. We have also demonstrated that MKK3 may be critical for airway neutrophilia, but not eosinophilia, suggesting that this may be a target worthy of further consideration in the context of diseases associated with neutrophil activation such as severe asthma and COPD.

Regulating cough through modulation of sensory nerve function in the airways.

Whilst local anaesthetics when applied directly to laryngeal nerves or topically to the lung can suppress cough, their chronic use is constrained because of dose limiting side effects. However, the effectiveness of local anaesthetics suggests that selectivity targeting nerves in the airway may provide novel approaches for the treatment of cough in the future. There is a considerable wealth of evidence showing that there are different afferent nerve subtypes in the airways. Traditionally C-fibres have been the focus of much research in the cough field since the stimulation of these afferents by capsaicin is able to elicit cough in guinea-pigs and in man, and drugs targeting various proteins expressed in these nerves (e.g. mu-opioid, NOP1, TRPV1, sodium channels) have been shown to be anti-tussive in preclinical models of cough. However, interest in Aδ fibres has increased recently in light of the discovery of a specific cough receptor in the guinea-pig that is provoked by citric acid and punctate stimulation, but not capsaicin and which has been anatomically linked to Aδ fibres. There is also some evidence that as a result of inflammation in the airways, Aδ fibres can begin to express neuropeptides and TRPV1 receptors so that they can become responsive to endogenous activators of this ion channel and to irritants like capsaicin. Consequently, there is considerable interest in targeting either one or both afferent nerve types for the treatment of chronic cough. However, to date the translation of preclinical studies into man has largely been disappointing and certainly there is a need for better preclinical models in this field. There also remain many challenges to overcome at a clinical level, such as what patient group(s) should be used to assess anti-tussive drugs and whether the use of irritants that induce cough in healthy volunteers (such as citric acid or capsaicin) is of any value in the assessment of novel anti-tussive drugs. The development of several continuous monitoring methodologies for measuring cough will hopefully allow better evaluation of treatments in patients with chronic cough. Nonetheless, cough remains a major unmet clinical need in respiratory medicine where new drugs are urgently required.

The effects of cannabidiol on the antigen-induced contraction of airways smooth muscle in the guinea-pig.

(-)-Δ(9)-Tetrahydrocannabinol has been demonstrated to have beneficial effects in the airways, but its psychoactive effects preclude its therapeutic use for the treatment of airways diseases. In the present study we have investigated the effects of (-)-cannabidiol, a non-psychoactive component of cannabis for its actions on bronchial smooth muscle in vitro and in vivo. Guinea-pig bronchial smooth muscle contractions induced by exogenously applied spasmogens were measured isometrically. In addition, contractile responses of bronchial smooth muscle from ovalbumin-sensitized guinea-pigs were investigated in the absence or presence of (-)-cannabidiol. Furthermore, the effect of (-)-cannabidiol against ovalbumin-induced airway obstruction was investigated in vivo in ovalbumin-sensitized guinea-pigs. (-)-Cannabidiol did not influence the bronchial smooth muscle contraction induced by carbachol, histamine or neurokinin A. In contrast, (-)-cannabidiol inhibited anandamide- and virodhamine-induced responses of isolated bronchi. A fatty acid amide hydrolase inhibitor, phenylmethanesulfonyl fluoride reversed the inhibitory effect of (-)-cannabidiol on anandamide-induced contractions. In addition, (-)-cannabidiol inhibited the contractile response of bronchi obtained from allergic guinea-pigs induced by ovalbumin. In vivo, (-)-cannabidiol reduced ovalbumin-induced airway obstruction. In conclusion, our results suggest that cannabidiol can influence antigen-induced airway smooth muscle tone suggesting that this molecule may have beneficial effects in the treatment of obstructive airway disorders.

The mechanism of action of doxofylline is unrelated to HDAC inhibition, PDE inhibition or adenosine receptor antagonism.

Xanthines such as theophylline have been used in the treatment of lung diseases since the early 1900's, but have a major drawback of a very narrow therapeutic window and many drug/drug interactions. This means that plasma levels have to be measured regularly and can make the use of theophylline problematic. With the increasing availability of other classes of drugs for the treatment of respiratory diseases, this has limited the use of xanthines, despite their clear clinical benefit in the treatment of patients with asthma and COPD. Doxofylline is a xanthine molecule having both bronchodilator and anti-inflammatory activity with an improved therapeutic window over conventional xanthines such as theophylline. However, the mechanistic basis of this improved therapeutic window is not understood. The present study has investigated some pharmacological activities of doxofylline in comparison with theophylline. Doxofylline does not directly inhibit any of the known HDAC enzymes, and did not inhibit any PDE enzyme sub types or act as an antagonist at any of the known adenosine receptors, except for PDE2A(1), and adenosine A(2A) and only at the highest tested concentration (10(-4) M). These results may explain the improved tolerability profile of doxofylline compared with theophylline.

Effects of heparin and related drugs on neutrophil function.

We have previously demonstrated that heparin inhibits neutrophil activation, but the precise mechanism of action remains to be elucidated. The current aim was to further investigate the effects of heparin at inducing apoptosis of neutrophils and whether this was related to antagonism at IP(3) receptors. Furthermore, we investigated the ability of heparin and related molecules to inhibit acute neutrophil-induced injury to human bronchial epithelial cells (HBECs) in vitro. Neutrophils were isolated from human peripheral venous blood. Expression of annexin-V was determined in neutrophils following incubation with LMWH. The effects of LMWH and related molecules upon thapsigargin or m-3M3FBS (phospholipase C activator) induced neutrophil elastase (NE) release were also investigated. The cytotoxic effects of fMLP-activated neutrophils following co-incubation with HBECs were quantified through counting adherent cells before and after incubation. There was no detectable increase in annexin-V positive neutrophils following pre-incubation with LMWH at 30 min, 60 min or 16 h, but an increase was observed with Fas-activating antibody at 16 h. LMWH significantly inhibited NE release induced by either m-3M3FBS (73.4 ± 6.1%, 100 IU ml(-1), P < 0.01) or thapsigargin (62.4 ± 6.9%, 100 IU ml(-1), P < 0.01) in a sulphate-dependent manner. LMWH and related sulphated molecules all abrogated the cytotoxic effects of fMLP-activated neutrophils upon HBECs. In conclusion we were not able to demonstrate that heparin induces apoptosis and we did not find any evidence for heparin acting as an IP(3) receptor antagonist in neutrophils. Nonetheless, the potent inhibitory effects of heparin and related molecules upon neutrophil-induced injury to HBECs provide further evidence of the therapeutic potential of heparin and related molecules in the treatment of chronic inflammatory diseases.

Phosphodiesterase inhibitors in the treatment of inflammatory diseases.

Phosphodiesterase 4 (PDE4) belongs to a family of enzymes which catalyzes the breakdown of 3, 5'-adenosine cyclic monophosphate (cAMP) and is ubiquitously expressed in inflammatory cells. There is little evidence that inflammatory diseases are caused by increased expression of this isoenzyme, although human inflammatory cell activity can be suppressed by selective PDE4 inhibitors. Consequently, there is intense interest in the development of selective PDE4 inhibitors for the treatment of a range of inflammatory diseases, including asthma, chronic obstructive pulmonary disease (COPD), inflammatory bowel disease, and psoriasis. Recent clinical trials with roflumilast in COPD have confirmed the therapeutic potential of targeting PDE4 and recently roflumilast has been approved for marketing in Europe and the USA, although side effects such as gastrointestinal disturbances, particularly nausea and emesis as well as headache and weight loss, may limit the use of this drug class, at least when administered by the oral route. However, a number of strategies are currently being pursued in attempts to improve clinical efficacy and reduce side effects of PDE4 inhibitors, including delivery via the inhaled route, development of nonemetic PDE4 inhibitors, mixed PDE inhibitors, and/or antisense biologicals targeted toward PDE4.

A novel murine model of pulmonary fibrosis: the role of platelets in chronic changes induced by bleomycin.

Idiopathic pulmonary fibrosis (IPF) is a disease that causes scarring and destruction of lung tissue that is ultimately fatal. There is a need to develop improved treatments for IPF. One problem with identifying novel treatments of IPF is the poor predictability of current preclinical models. Few model investigate lung function changes, rather relying on histological changes which doesn't adequately reflect the complete clinical situation. The aim of this study was to establish a novel model of pulmonary fibrosis where we could investigate changes in lung function, and histology. We have also utilised this model to investigate the role of platelets in pulmonary fibrosis as platelets have been recognised as having a broader role than just facilitating haemostasis. Lung fibrosis was induced in male C57BL6/J mice by intranasal bleomycin on Days 0, 1, 2, 5, 6 and 7. Platelets were depleted by twice-weekly administration of anti-platelet antibodies. On Day 35 mice were assessed by examining lung function, platelet infiltration into lung tissues and bronchoalveolar lavage fluid (BAL), levels of BAL Tissue growth factor (TGF)-ß levels, and the degree of fibrosis evaluated histologically. Repeated bleomycin administration caused loss of lung function associated with fibrosis assessed histologically. Platelet depletion resulted in a reduction in fibrosis and modest inhibition of lung function changes. We have established a novel model of pulmonary fibrosis that is associated with a decline in lung function similar to the clinical setting. Furthermore, platelet depletion resulted in a less severe fibrosis suggesting that targeting platelets maybe worth further investigation.

The therapeutic efficacy of erdosteine in the treatment of chronic obstructive bronchitis: a meta-analysis of individual patient data.

UNLABELLED: Erdosteine, a drug approved for the treatment of acute and chronic pulmonary diseases, has been shown to be an effective treatment for chronic bronchitis or COPD (CB/COPD) in several studies, although marked differences in the perception of its usefulness still remain. AIM: to test the available evidence for the efficacy of erdosteine in adults with stable or exacerbated CB/COPD. METHODS: Meta-analysis of individual patient data from both published and unpublished randomized controlled trials (RCTs) comparing erdosteine with placebo/mucolytics, given for up to 10 days in association with standard therapy (RCTs used for regulatory drug approval). Individual patient data were provided by the manufacturer of erdosteine, Edmond Pharma (Milano, Italy). Endpoints were symptom scores (cough frequency and intensity, sputum viscosity and purulence, difficulty to expectorate, catarrh rhonchi at auscultation, dyspnoea), a cumulative global efficacy index (cGEI), and an overall physician efficacy assessment (OA). RESULTS: individual data from 1046 patients from 15 RCTs (12 on exacerbated and 3 on stable CB/COPD) were obtained. Erdosteine induced a significant reduction of cGEI vs comparators (-1.02; 95% CI: from -1.60 to -0.44; p=0.0006), both placebo and mucolytics. On individual symptoms, it positively impacted on cough frequency (-0.19; 95% CI: from -0.34 to -0.03) and intensity (-0.30; 95% CI: from -0.44 to -0.17), sputum viscosity (-0.28; 95% CI: from -0.49 to -0.07), difficulty to expectorate (-0.24; 95% CI: from -0.40 to -0.08), and catarrh ronchi at auscultation (-0.35; 95% CI: from -0.60 to -0.10). The effects on dyspnoea were only significant vs placebo, whereas sputum purulence was not significantly modified. The OA also favoured erdosteine, doubling the chance of success compared with placebo and mucolytics: OR (odds ratio) 2.06; (95% CI: from 1.27 to 3.33). The treatment with erdosteine was well tolerated. Adverse events, mainly gastrointestinal, were reported by 10.2% of patients compared to 11.0% in the reference groups. CONCLUSIONS: Treatment with erdosteine is associated with a significant benefit in terms of symptom amelioration both vs placebo and mucolytics in patients with CB/COPD. Although with some limitations (e.g. not fully validated scores) this review reinforces the use of erdosteine, in combination with standard therapy, in respiratory diseases characterized by increased expectoration, namely acute CB/COPD exacerbations.

Radiolabelling and immunohistochemistry reveal platelet recruitment into lungs and platelet migration into airspaces following LPS inhalation in mice.

INTRODUCTION: Platelets are under investigation for their role in host defence and inflammatory lung diseases and have been demonstrated to be recruited to the lung. However, the mechanisms and consequences of platelet recruitment into lungs are poorly understood. We have utilised a murine model to investigate the mechanisms of platelet involvement in lung inflammation induced by intranasal administration of LPS. OBJECTIVES: Our aim was to characterise lung platelet recruitment following LPS inhalation in mice using immunohistochemistry, and non-invasive and invasive radiolabelled platelet tracking techniques. RESULTS: Intranasal administration of LPS caused an increase in lung platelet staining in lung tissue and elicited the recruitment of radiolabelled platelets into the lung. Prior to these responses in the lung, we observed an earlier decrease in blood platelet counts, temporally associated with platelet recruitment to the liver and spleen. Non-invasive measurements of thoracic radioactivity reflected changes in blood counts rather than extravascular lung platelet recruitment. However, both in situ counting of radiolabelled platelets and immunostaining for platelet surface markers showed LPS-induced increases in extravascular platelets into lung airspaces suggesting that some of the platelets recruited to the lung enter air spaces. CONCLUSIONS: Intranasal administration of LPS activates the innate immune response which includes a fall in peripheral blood platelet counts with subsequent platelet recruitment to the lung, spleen and liver, measured by immunohistochemistry and radiolabelling techniques.

Peripheral mechanisms II: the pharmacology of peripherally active antitussive drugs.

Cough is an indispensable defensive reflex. Although generally beneficial, it is also a common symptom of diseases such as asthma, chronic obstructive pulmonary disease, upper respiratory tract infections, idiopathic pulmonary fibrosis and lung cancer. Cough remains a major unmet medical need and although the centrally acting opioids have remained the antitussive of choice for decades, they have many unwanted side effects. However, new research into the behaviour of airway sensory nerves has provided greater insight into the mechanisms of cough and new avenues for the discovery of novel non-opioid antitussive drugs. In this review, the pathophysiological mechanisms of cough and the development of novel antitussive drugs are reviewed.

Elevated expression of adenosine A1 receptor in bronchial biopsy specimens from asthmatic subjects.

Asthmatics, unlike healthy subjects, experience bronchoconstriction in response to inhaled adenosine, and extracellular adenosine concentrations are elevated in the bronchoalveolar lavage fluid and exhaled breath condensate of asthmatic subjects. However, little is known about the location and expression of adenosine receptors in asthmatic airways. The aim of the present study was to investigate the distribution of adenosine A(1) receptors in bronchial biopsy specimens from mildly asthmatic steroid-naïve subjects and then compare the degree of expression with that of healthy subjects. Biopsy sections were immunostained using an adenosine A(1) receptor antibody, the selectivity of which was validated in specific experiments. Image analysis was then performed in order to determine differences in immunostaining intensity. Immunostaining of biopsy sections from the asthmatic subjects revealed strong expression of the A(1) receptor, located predominantly in the bronchial epithelium and bronchial smooth muscle. In comparison, very weak immunostaining was observed in biopsy specimens obtained from healthy subjects. Image analysis revealed that the intensity of positive staining of the asthmatic bronchial epithelium and smooth muscle regions was significantly greater than that observed for the healthy epithelium and smooth muscle. In conclusion, the sensitivity of asthmatics to inhaled adenosine coupled with increased adenosine A(1) receptor expression implies that these receptors play a role in the pathophysiology of this disease.

Outcomes for COPD pharmacological trials: from lung function to biomarkers.

The American Thoracic Society/European Respiratory Society jointly created a Task Force on "Outcomes for COPD pharmacological trials: from lung function to biomarkers" to inform the chronic obstructive pulmonary disease research community about the possible use and limitations of current outcomes and markers when evaluating the impact of a pharmacological therapy. Based on their review of the published literature, the following document has been prepared with individual sections that address specific outcomes and markers, and a final section that summarises their recommendations.