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Notes: Background Gastrooesophageal reflux (GER) is a frequent cause of chronic cough. Several investigators have indicated that inhibitors of H+K+ATPase (proton pump inhibitors; PPIs) could relieve coughing via inhibition of acid reflux. However, we considered that PPIs might directly inhibit increased cough reflex sensitivity.Objective The present study was designed to examine whether PPIs directly inhibit antigen-induced increase in cough reflex sensitivity and to elucidate the mechanism.Methods Actively sensitized guinea-pigs were challenged with aerosol antigen (ovalbumin, OVA) and cough reflex sensitivity to inhaled capsaicin was measured 24 h later. The PPIs (omeprazole and rabeprazole) or the histamine H2 blocker cimetidine were administered intraperitoneally 1 h before OVA challenge and before measuring cough reflex sensitivity, then bronchoalveolar lavage fluid (BALF) was immediately collected. The pH of the fluid obtained by bronchial washing was determined after examining the effect of rabeprazole on the cough response to capsaicin.Results The number of coughs elicited by capsaicin was significantly increased 24 h after challenge with OVA compared with saline, indicating antigen-induced increase in cough reflex sensitivity. Both PPIs dose dependently and significantly inhibited antigen-induced cough hypersensitivity. Omeprazole did not influence the antigen-induced increase in the total number of cells or ratio (%) of eosinophils in BALF. Cimetidine did not affect the antigen-induced cough hypersensitivity or cellular components of BALF. The pH of the bronchial washing fluid was significantly decreased in antigen-challenged animals. Rabeprazole did not affect the antigen-induced decrease in the pH of bronchial washing fluid.Conclusion These findings show that PPIs, but not histamine H2 blockers, can directly decrease antigen-induced cough reflex hypersensitivity, while the mechanism remains unclear.

Notes: Background Cough receptor hypersensitivity is a fundamental feature of some conditions presenting with chronic non-productive cough. Suplatast tosilate, an anti-allergic agent, is a T helper (Th)2 cytokine inhibitor that inhibits the synthesis of interleukin (IL)-4, IL-5, immunoglobulin (Ig)E production, and local eosinophil accumulation.Objective The purpose of this study was to investigate the effect of suplatast on antigen-induced airway cough hypersensitivity and eosinophil infiltration into the airway.Methods Number of coughs elicited by inhalation of increasing concentrations of capsaicin (10−8, 10−6 and 10−4 M) was counted 24 h after an antigen challenge in conscious guinea-pigs and then bronchoalveolar lavage was performed. We investigated the effect of single (before antigen challenge or capsaicin provocation) or repetitive treatment with intraperitoneal suplatast at a dose of 10 or 30 mg/kg on antigen-induced cough hypersensitivity.Results Twenty-four hours after antigen challenge, guinea-pigs developed an increase in cough receptor sensitivity to inhaled capsaicin and eosinophil infiltration in the airways. After a 2-week treatment with suplatast, but not after only a single treatment before antigen challenge or capsaicin provocation, the antigen-induced early phase bronchoconstriction, cough hypersensitivity, and airway eosinophilia were inhibited in a dose-dependent manner.Conclusion These results indicate that suplatast inhibits airway cough hypersensitivity underlying allergic eosinophilic inflammation.

Notes: Background Administration of propranolol can provoke bronchoconstriction only in asthmatic patients. Recently we developed an animal model for propranolol-induced bronchoconstriction (PIB). Our working hypothesis is that such bronchoconstriction may result from the inflammatory mediators released by an allergic reaction.Objectives Our goal in this study was to determine which products of arachidonate 5-lipoxygenase pathway are involved in the PIB.Methods Propranolol at a concentration of 10mg/mL was inhaled 20min after antigen challenge in passively sensitized, anaesthetized and artificially ventilated guinea-pigs. Two different sulfidopeptide leukotriene (s-LT) antagonists, ICI198 615 in the doses of 0.03 and 0.3 mg/kg and vehicle and KCA757 in the doses of 1 and 5 mg/kg and vehicle, and a LTB4 antagonist ONO4057 in the doses of 1 and 10 mg/kg and vehicle were injected intravenously 15min after antigen challenge. Effects of an anticholinergic agent atropine sulphate (5 mg/kg) and an α-adrenergic biocker pbentolamine (0.3 and 3 mg/kg) were exatnined in the same way.Results Bronchoconstriction occurred when 10 mg/mL of propranolol was inhaled 20 min after antigen challenge. Both ICI198 615 and KCA757 administered intravenously 15 min after antigen challenge reduced the PIB in a dose-dependent manner while ONO4057 did not alter the PIB. Atropine or phentolamine did not change the PIB.Conclusions These results suggest that mediator mechanism, but not cholinergic or α-adrenergic nerve, is important in the PIB which developed after the allergic bronchoconstriction in our guinea-pig model and that s-LTs but not LTB4 have an important role in the pathophysiology of the PIB.

Notes: Increased sensitivity of cough reflex is a fundamental feature of bronchodilator resistant non-productive cough associated with eosinophilic tracheobronchitis. Our hypothesis is that cough sensitivity is increased by airway allergic reaction characterized by airway eosinophilic inflammation. The aim of this study was to elucidate the hypothesis and clarify the characteristics of the increased cough sensitivity.Number of coughs elicited by inhalation of increasing concentrations of capsaicin (10−8, 10−6 and 10−4 m) was counted 24 h after an aerosolized antigen or saline in actively sensitized or non-sensitized (naive) conscious guinea pigs and then bronchoalveolar lavage was performed. The cough response was also measured 1 day before and 1, 2, 3, 5 and 7 days after an aerosolized antigen challenge in sensitized or naive animals. In addition, effect of procaterol (0.1 mg/kg), atropine (1 or 10 mg/kg), phosphoramidon (2.5 mg/kg) given intraperitoneally 30 min before the capsaicin challenge or capsaicin desensitization on the cough response was examined. Furthermore, the thromboxane A2 (TXA2) receptor antagonist S-1452 in a dose of 0.01 or 0.1 mg/kg or vehicle (saline) was given intraperitoneally at 24 and 1 h before the measurement of cough response.Number of coughs caused by capsaicin was extremely increased 24 h after an antigen challenge in sensitized guinea pigs compared with a saline or an antigen challenge in naive animals or a saline challenge in sensitized animals. The increased cough response disappeared at 3–7 days after the antigen challenge. Eosinophils in bronchoalveolar lavage fluid obtained after the measurement of capsaicin-induced coughs, which was performed 24 h after the antigen challenge, were significantly increased in sensitized guinea pigs. The eosinophil count was significantly correlated to the number of capsaicin-induced coughs. Procaterol or atropine did not alter the antigen-induced increase of cough sensitivity, whereas atropine did reduce the cough response in naive animals. Phosphoramidon increased the number of capsaicin-induced coughs in naive guinea pigs but not in sensitized and antigen-challenged animals. Capsaicin desensitization decreased the cough response in both antigen-challenged sensitized guinea pigs and naive animals. S-1452 reduced the antigen-induced increase of cough response in sensitized guinea pigs, but not in naive animals.Airway allergy accompanied with airway eosinophilia induces transient increase in cough sensitivity, which is not mediated by bronchoconstriction. The increased cough sensitivity may result in part from inactivation of neutral endopeptidase and TXA2, one of the inflammatory mediators.

Notes: Background We previously reported that inhaled acetaldehyde, a metabolite of ethanol atid a maiti factor in alcohol-induced asthma, causes bronchial hyper-responsiveness (BHR) in asthmatics. However, the mechanisms are unclear.Objective The purpose of this study was to investigate a role of a peptide leukotriene (LT) in acetaldehyde-induced BHR.Methods Effects of LT antagonists, ONO-1078 (O.l-l.Omg/kg) and ICI-198, 615 (0.03–0.3 mg/kg), on acetaldehyde-induced bronchoconstriction and BHR to inhaled methacho-line were examined using a modified Konzett-Rössler method in guinea pigs.Results Aeetaldehyde at 0.8mg/ml, which failed to induce significant changes in Pao (pressure at the airway opening), enhanced an increase in Pao induced by subsequent inhalations of ascending doses (50–200 μg/ml) of methacholine. suggesting a potentiating effect of acetaldehyde oti bronchial responsiveness. Although ONO-1078 had no inhibitory effect on bronchoconstriction caused by ascending doses (5.0–20 mg/ml) of acetaldehyde, ONO-1078 and ICI-198, 615 reduced the acetaldehyde-induced BHR.Conclusion Acetaldehyde causes BHR via LT release in guinea-pigs.

Notes: Background Administration of propranolol can provoke bronchoconstriction in asthmatic patients. We hypothesized that such bronchoconstriction may result from the inflammatory mediators released by an allergic reaction. We recently developed a guinea pig model for propranolol-induced bronchoconstriction (PIB). Neuropeptides which are released from C-fibre nerve endings have been postulated to induce bronchial hyperresponsiveness through neurogenic inflammation.Objective The purpose of this study was to examine whether sensory neuropeptides are involved in the development of PIB after allergic reaction.Methods Propranolol at a concentration of 10mg/ml was inhaled 20min after antigen challenge in passively sensitized, anaesthetized and artificially ventilated guinea pigs. The animals were treated intravenously with a NK1 and NK2 dual antagonist, FK224, in a dose of 1 or 10 mg/kg or vehicle or a selective NK1 antagonist, FK888, in a dose of 1 or 10mg/kg or vehicle 10min before or 15min after antigen challenge.Results Propranolol inhaled 20 min after antigen challenge caused bronchoconstriction. FK224 or FK888 administered 15 min after antigen challenge as well as 10 min before antigen challenge did not reduce the PIB.Conclusion We conclude that neuropeptides such as neurokinin A and substance P do not directly contribute to the development of PIB after allergic reaction.

Notes: It was reported that ethanol–induced bronchoconstriction was associated with elevated serum levels of aectaldehyde and histamine in Japanese asthmatic patients, but there is no study to investigate the airway response to acetaldehyde. We performed this animal study to test the hypothesis that acctaldehyde has the bronchospastic action via histamine release. First, we investigated the airway response to ascending doses (31.3, 62.5, 125. and 250 MM) of inhaled ethanol or acctaldehyde in guinea–pigs. Secondly, guinea–pigs pretreated with intraperitoneal injection of saline or 20 mg/kg diphenhydramine inhaled acetaldehyde. Finally, guinea–pigs pretreated with intraperitoneal injection of saline or 0–5 mg/kg atropine sulfate inhaled acetaldehyde. Inhalation of acetaldehyde. but not ethanol, caused bronchoconstriction in a dose–dependent manner. The bronchoconstriction induced by inhaled acetaldehyde was completely prevented by pretreatment with diphenhydramine. Atropine had no preventing effect against the acetaldehyde–induced bronchoconstriction. In conclusion, acetaldehyde has the bronchospastic action via histamine release in guinea–pigs. It is suggested that histamine HI–antagonists may be available for preventing alochol–induced asthma.

Notes: Background Indoor formaldehyde (FA) might worsen allergies and be an underlying factor for the increasing incidence and severity of asthma; the exact mechanism, however, remains unclear.Objective The present study examined the effects of repeated exposure to FA on methacholine- and antigen-induced bronchoconstriction in guinea-pigs in vivo.Methods First, non-sensitized guinea-pigs were transnasally treated with 0.1 or 1.0% FA or saline three times a week for 6 weeks, and increasing concentrations of methacholine (50, 100, and 200 μg/mL) were inhaled at 5-min intervals. Second, guinea-pigs pre-treated with transnasal administration of FA or saline using the same protocol were passively sensitized with anti-ovalbumin (OA) serum 7 days before antigen challenge. Third, guinea-pigs were actively sensitized with OA and pre-treated with transnasal administration of FA or saline using the same protocol. The lateral pressure of the tracheal tube (Pao) was measured under anesthesia and artificial ventilation.Results The antigen-induced increase in Pao in actively sensitized guinea-pigs was significantly potentiated by FA exposure in a dose-dependent manner. The dose–response curve of the methacholine-induced increase in Pao in non-sensitized guinea-pigs or of the antigen-induced increase in Pao in passively sensitized guinea-pigs was not altered by FA exposure. Transnasal administration of FA significantly increased the serum anti-OA homocytotropic antibody titre (IgG) as measured by the passive cutaneous anaphylaxis reaction in actively sensitized guinea-pigs.Conclusion The results suggest that repeated exposure to FA worsens allergic bronchoconstriction through enhancing antigen sensitization.

Notes: Background Chronic desquamative eosinophilic bronchitis and bronchial hyperresponsiveness have been considered essential for bronchial asthma. However, it has not been studied whether airway eosinophils enhance or inhibit bronchial responsiveness in vivo.Objective This study was conducted to elucidate the influence of airway eosinophil accumulation on bronchial responsiveness in vivo.Materials and methods Guinea pigs were transnasally treated with 75 µg/kg of polymyxin-B or vehicle twice a week for a total of 3 weeks. Guinea pigs were surgically cannulated and artificially ventilated 24 h after the last administration of polymyxin-B or vehicle. Ten minutes after the installation of artificial ventilation, ascending doses of methacholine, acetylcholine or histamine were inhaled for 20 s at intervals of 5 min. Subsequent study was conducted 20 min after treatment of 60 mg/kg of indomethacin in the same manner. Final study was conducted in naive guinea pigs after single inhalation of 75 µg/mL of polymyxin B.Results The proportion of eosinophils in bronchoalveolar lavage fluid significantly increased in guinea pigs treated with polymyxin-B compared with vehicle. Bronchial responsiveness to inhaled methacholine, acetylcholine and histamine was significantly decreased by the polymyxin-B treatment. This protective effect induced by polymyxin B was abolished by pretreatment of indomethacin. A significant increase in bronchial responsiveness was observed after a single inhalation of polymyxin B.Conclusion These results suggest that in vivo airway eosinophils may reduce non-specific bronchial responsiveness through inhibitory or bronchoprotective prostanoids.

Notes: No study has investigated the effects of ethanol on bronchial responsiveness in patients with alcohol-induced asthma, although acetaldehyde, which is a metabolite of ethanol and is thought to be a main factor in alcohol-induced asthma, causes both bronchoconstriction and bronchial hyperresponsiveness. The purpose of this study was to investigate the direct action of ethanol on the airway in patients with alcohol-induced asthma. First, we investigated the bronchial response to inhalation of ascending doses (5, 10, and 20%) of ethanol in nine patients with alcohol-induced asthma. Then, the bronchial responsiveness to methacholine was measured in 14 patients who were pretreated with saline or 20% ethanol in a double-blind, randomized, placebo-controlled, crossover fashion. Ascending doses of inhaled ethanol caused no significant changes in FEV1. The methacholine concentrations producing a 20% fall in FEV1 (PC20-MCh) after 20%) ethanol (0.769 mg/ml, GSEM 1.514) were significantly (P= 0.0357) higher than those after saline (0.493 mg/ml, GSEM 1.368). This indicates that ethanol has a reducing effect on nonspecific bronchial responsiveness in patients with alcohol-induced asthma; this paper is the first report on the effects of ethanol on bronchial responsiveness.