Role of COX-2 in cough reflex sensitivity to inhaled capsaicin in patients with sinobronchial syndrome.

BACKGROUND: Sinobronchial syndrome is a cause of chronic productive cough. Inflammatory mediators are involved in the pathophysiology of chronic productive cough. Accumulating evidences indicate that cyclooxygenase (COX)-2, one of the inducible isoforms of COX, is a key element in the pathophysiological process of a number of inflammatory disorders. However, little is known about the role of COX-2 in chronic productive cough in patients with sinobronchial syndrome known as neutrophilic bronchial inflammation. METHODS: The effect of etodolac, a potent COX-2 inhibitor, on cough response to inhaled capsaicin was examined in 15 patients with sinobronchial syndrome in a randomized, placebo-controlled cross-over study. Capsaicin cough threshold, defined as the lowest concentration of capsaicin eliciting five or more coughs, was measured as an index of airway cough reflex sensitivity. RESULTS: The cough threshold was significantly (p < 0.03) increased after two-week treatment with etodolac (200 mg twice a day orally) compared with placebo [37.5 (GSEM 1.3) vs. 27.2 (GSEM 1.3) muM]. CONCLUSIONS: These findings indicate that COX-2 may be a possible modulator augmenting airway cough reflex sensitivity in patients with sinobronchial syndrome.

Antitussive effects of the leukotriene receptor antagonist montelukast in patients with cough variant asthma and atopic cough.

BACKGROUND: Chronic cough is the only symptom of cough variant asthma (CVA) and atopic cough (AC). Cysteinyl leukotriene receptor antagonists have been shown to be effective in CVA, but there are no reports on their effectiveness in AC. To evaluate the antitussive effect of montelukast, a leukotriene receptor antagonist, in CVA and AC. METHODS: Seventy-five patients with chronic cough received diagnostic bronchodilator therapy with oral clenbuterol hydrochloride for 6 days. Of the 75 patients, 48 and 27 met the simplified diagnostic criteria for CVA and AC, respectively. Patients with CVA were randomly divided into 3 groups: montelukast, clenbuterol, and montelukast plus clenbuterol. Patients with AC were randomly divided into 2 groups: montelukast and placebo. The efficacy of cough treatment was assessed with a subjective cough symptom scale (0 meant "no cough" and 10 denoted "cough as bad as at first visit"). The cough scale, pulmonary function test, and peak expiratory flow rate (PEF) were evaluated before and after 2 weeks of treatment. RESULTS: In patients with CVA, 2-week treatment with montelukast, clenbuterol, and montelukast plus clenbuterol all significantly decreased cough scores and treatment with montelukast plus clenbuterol was superior to treatment with montelukast alone. In the montelukast plus clenbuterol group, PEF values in the morning and evening significantly increased after 2 weeks compared with values before treatment. In patients with AC, scores on the cough scale did not differ significantly between the montelukast group and the placebo group. CONCLUSIONS: Montelukast was confirmed to suppress chronic non-productive cough in CVA, whereas it was not effective in non-productive cough in AC.

Airway wall structure assessed by endobronchial ultrasonography and bronchial hyperresponsiveness in patients with asthma.

BACKGROUND AND OBJECTIVE: The purpose of this study was to evaluate the relationship between the wall structure assessed by using endobronchial ultrasonography (EBUS) and bronchial hyperresponsiveness in patients with asthma. METHODS: Twenty-four patients with stable asthma and 11 individuals without asthma were studied. EBUS was performed with a radial 20-MHz ultrasonic probe inserted into the intermediate bronchus undergoing flexible bronchoscopy to assess the airway wall structure. The percentage of airway wall thickness {WT%; defined as [(ideal outer diameter-ideal luminal diameter)/ideal outer diameter]×100} was determined by EBUS. We measured bronchial hyperresponsiveness to methacholine [the provocative concentration of methacholine causing a decrease of 20% or more in forced expiratory volume in 1 s (PC20)]. RESULTS: Percentage wall thickness measured by EBUS was significantly greater in patients with asthma than that in subjects without asthma (P<0.01). The evaluation of the laminar structure using EBUS indicated that the thickness of the second layer in patients with asthma was greater than that in subjects without asthma (P<0.05). PC20 was negatively correlated with the thickness of the second layer (r=0.52, P<0.01) but was not significantly correlated with other layers in patients with asthma. CONCLUSIONS: The evaluation of the bronchial mural structure using EBUS might be advantageous for assessing the relationship between airway wall remodeling and bronchial hyperresponsiveness.

Effects of KF19514, a phosphodiesterase 4 and 1 Inhibitor, on bronchial inflammation and remodeling in a murine model of chronic asthma.

BACKGROUND: Phosphodiesterase 4 selective inhibitor may prevent airway inflammation and remodeling. OBJECTIVE: The aim of this study was to investigate the effects of KF19514, a phosphodiesterase 4 and 1 dual inhibitor, on chronic airway inflammation and remodeling following chronic exposure to aerosolized antigen in mice. METHODS: Ovalbumin (OVA) was administered intraperitoneally to BALB/c mice on days 0 and 14, and the mice were then exposed to aerosolized OVA daily for 4 weeks. Twenty-four hours following the final inhalation, bronchial responsiveness to acetylcholine was measured, and histologic examination and hydroxyproline content of the lung were evaluated. RESULTS: Bronchial responsiveness to acetylcholine, number of inflammatory cells and eosinophils in the lamina propria, thickness of epithelial and subepithelial collagen layers, and hydroxyproline content of the lung increased following chronic exposure to OVA for 7 weeks. KF19514 significantly prevented all of these changes. CONCLUSIONS: Phosphodiesterase 4 and 1 inhibitors such as KF19514 may help prevent bronchial hyperresponsiveness and chronic asthma-induced airway remodeling.

Effect of an orally active Th2 cytokine inhibitor, suplatast on "atopic cough" tosilate.

BACKGROUND: "Atopic cough" is a new clinical entity that presents with isolated chronic bronchodilator-resistant cough accepted in the Japanese Respiratory Society Guidelines for Management of Cough. The essential features are eosinophilic tracheobronchitis, increased cough reflex sensitivity and an atopic constitution. It has been suggested that activated helper T lymphocytes and the cytokines which are produced by these cells are involved in the pathogenesis, but the relationship between helper T cell-derived cytokines and the airway cough reflex sensitivity remains unknown. METHODS: The effect of an orally active Th2 cytokine inhibitor, suplatast tosilate (CAS 94055-76-2, IPD; 300 mg/day), on the cough response to inhaled capsaicin (CAS 404-86-4) was examined in ten patients with atopic cough. The capsaicin cough threshold, defined as the lowest concentration of capsaicin eliciting five or more coughs, was measured as an index of airway cough reflex sensitivity. The serum total immunoglobulin E (IgE) level and the peripheral blood eosinophil count were also determined after treatment with suplatast tosilate. RESULTS: The cough threshold measured after four weeks of treatment with suplatast tosilate was significantly increased compared to the value obtained with placebo, along with a decrease of the serum IgE level and peripheral eosinophil count. CONCLUSIONS: Th2 cytokines may increase the airway cough reflex sensitivity in patients with atopic cough. Oral administration of suplatast tosilate may be a novel therapy for atopic cough.

Sputum eosinophilia, airway hyperresponsiveness and airway narrowing in young adults with former asthma.

BACKGROUND: 30-80% of outgrown asthma subjects develop symptoms again later in life. We investigated inflammation and function of lower airway in adolescents with former asthma. METHODS: 326 never-smoking young adults (mean age 24.0 years) were interviewed with special emphasis on history of asthma. Diagnosis of asthma was based on GINA guidelines. Former asthma subjects consisted of ones with a history of physician-diagnosed childhood asthma, who had been free of asthma symptoms without the use of medication for at least 10 years prior to the study. Provocative concentration of methacholine causing a 20% fall in forced expiratory volume in 1 second (FEV(1))(PC(20)) and eosinophil percentage in induced sputum were measured. RESULTS: 31 subjects were former asthma subjects (FBA), 11 subjects were current asthma subjects (CBA) and 284 subjects had no history of asthma (non-BA). PC(20) and FEV(1)/FVC ratio were significantly lower in the FBA group than in the non-BA group (P < 0.01). Maximal mid-expiratory flow (MMF) was significantly lower in the FBA group than in the non-BA group (P < 0.05). Sputum eosinophil percentage was significantly increased in the FBA group compared with the non-BA group (P < 0.01). PC(20) was significantly lower in the CBA group than in the FBA and non-BA groups (P < 0.01). FEV(1), FEV(1)/FVC ratio and MMF were significantly lower in the CBA group than in the FBA group (P < 0.05, P < 0.05 and P < 0.05, respectively) and the non-BA group (P < 0.01, P < 0.01 and P < 0.05, respectively). Sputum eosinophils were significantly higher in the CBA group than in the FBA and non-BA groups (P < 0.01). CONCLUSIONS: This study shows that subjects with long-term outgrown asthma continue to have airway eosinophilic inflammation, airway hyperresponsiveness and airway narrowing.

Effect of pressure stress applied to the airway on cough-reflex sensitivity in Guinea pigs.

RATIONALE: We hypothesized that cough stress of the airway wall results in a self-perpetuating cough-reflex cycle in which antigen-induced increase in cough-reflex sensitivity results in pathologic cough, and the cough in turn further amplifies cough-reflex sensitivity. OBJECTIVES: To examine cough-reflex sensitivity in an experimental animal model. METHODS: We developed an experimental guinea pig model in which airway collapse similar to that in cough was induced by rapid negative pressure applied to the airway of artificially ventilated animals. We examined the influence of this stimulus on cough-reflex sensitivity to inhaled capsaicin and bronchoalveolar lavage (BAL) cell components. After the termination of artificial ventilation, the number of coughs due to capsaicin was measured, and BAL was performed. MEASUREMENTS AND MAIN RESULTS: Capsaicin cough-reflex sensitivity and the number of BAL neutrophils were increased 6 hours after stimulus application, decreasing to control levels by 24 hours. Cough-reflex sensitivity or BAL cell components were not changed in the absence of stimulus application. The number of BAL neutrophils correlated significantly with the number of coughs. Hydroxyurea inhibited the stimulus-induced increase in the number of coughs and airway neutrophil accumulation. CONCLUSIONS: Our findings suggest that cough itself is a traumatic mechanical stress to the airway wall that induces neutrophilic airway inflammation and cough-reflex hypersensitivity. Cough stress to the airway wall results in a self-perpetuating cough-reflex cycle.

Surfactant degradation activity in bronchoalveolar lavage fluid from guinea pigs challenged with antigen.

BACKGROUND AND OBJECTIVE: Surfactant dysfunction is a characteristic of bronchial asthma, but mechanisms of dysfunction following antigen exposure are not understood. The aim of this study was to examine whether bronchoalveolar lavage fluid (BALF) has surfactant degradation activity after antigen challenge, using an animal model of asthma. METHODS: BALF was collected 24 h after a challenge with aerosolized antigen solution in actively sensitized guinea pigs and from non-sensitized control guinea pigs. The surface tension of BALF was measured by pulsating bubble surfactometer. Surfactant activity was expressed as the minimum surface tension of BALF after 5 min of pulsation. BALF was separated into a cellular phospholipid fraction and supernatant, and reconstituted into 'pellet + supernatant' and 'pellet + saline' fractions. RESULTS: Surfactant activity of BALF from sensitized antigen-challenged animals was reduced after 4 h of incubation at 37 degrees C but a decrease was not observed in BALF from non-sensitized control animals. The decrease of surfactant activity in BALF from challenged animals was prevented by incubation at 4 degrees C. Disappearance of surfactant activity after incubation at 37 degrees C was observed in the 'pellet + supernatant', but not in the 'pellet + saline' fraction. The decrease of surfactant activity in BALF was also partially suppressed by the secretory phospholipase A2 inhibitor, indoxam, and by a cocktail of protease inhibitors. CONCLUSION: Surfactant-degrading activity was present in the supernatant of BALF from antigen-challenged guinea pigs. This activity may be attributed to secretory phospholipase A2 and to proteases present in the antigen-challenged airway.

Prostaglandin I2 enhances cough reflex sensitivity to capsaicin in the asthmatic airway.

Inflammatory mediators are involved in the pathogenesis of airway inflammation, but the role of prostaglandin I2 (PGI2) remains obscure. This study was designed to investigate the role of PGI2 in cough reflex sensitivity of the asthmatic airway, which is characterized by chronic eosinophilic airway inflammation. The effect of beraprost, a chemically and biologically stable analogue of PGI2, on cough response to inhaled capsaicin was examined in 21 patients with stable asthma in a randomized, placebo-controlled cross over study. Capsaicin cough threshold, defined as the lowest concentration of capsaicin eliciting five or more coughs, was measured as an index of airway cough reflex sensitivity. The cough threshold was significantly (p < 0.05) decreased after two weeks of treatment with beraprost [17.8 (GSEM 1.20) microM] compared with placebo [30.3 (GSEM 1.21) microM]. PGI2 increases cough reflex sensitivity of the asthmatic airway, suggesting that inhibition of PGI2 may be a novel therapeutic option for patients with asthma, especially cough predominant asthma.

Longitudinal changes of pulmonary function and bronchial responsiveness in cough-variant asthma treated with bronchodilators alone.

Cough due to cough-variant asthma (CVA) responds well to bronchodilators such as beta 2 adrenergic agonists. The aim of this study was to assess longitudinal changes of pulmonary function and bronchial responsiveness in CVA, which was treated with bronchodilators alone. Seventeen CVA patients recorded intensity and frequency of cough every day. Spirometry and provocative concentration of methacholine causing a 20% fall in forced expiratory volume in 1 second (PC20) were measured in the run-in period and after cough almost completely relieved on therapy. Cough score had improved within 2 weeks after the initiation of bronchodilator therapy. Forced expiratory volume in one second (FEV1) was significantly increased from 2.7 +/-0.7 L in the run-in period to 2.8+/-0.7 L after improvement of cough. However, the geometric mean (GSEM) PC20 value did not change from the run-in period [1542 (GSEM 1.29) microg/mL] to the time of improvement [2600 (GSEM 1.43) microg/mL]. Mildly increased bronchial responsiveness in CVA does not improve when only bronchodilator therapy is carried out. Because bronchial hyperresponsiveness has been shown to be a risk factor for typical asthma onset from CVA, the effect of inhaled corticosteroids on the longitudinal changes in bronchial responsiveness should be examined.

Bronchial asthma showing reduction in FEV1 after inhalation of Qvar.

The administration of Qvar (a hydrofluoroalkane-134a beclomethasone dipropionate; HFA-BDP) is highly useful for the treatment of patients with asthma. However, we found in a case of bronchial asthma that replacing the prior inhaled corticosteroids with Qvar resulted in temporary dyspnea and reduction in forced expiratory volume in 1 second (FEV1). Qvar contains beclomethasone dipropionate combined with absolute ethanol and an alternative to fluorocarbon. The patient had complicated alcohol-induced asthma. FEV1 decreased markedly and immediately after Qvar inhalation. The Qvar placebo is free of beclomethasone but contains other ingredients (ethanol and fluorocarbon). FEV1 did not decrease after the Qvar placebo, Aldecin inhalation, and Qvar inhalation orally treated with atropine before inhalation of Qvar. It seems unlikely that the components of Qvar (except beclomethasone) are responsible for the reduction in FEV1 observed immediately after inhalation of Qvar. These findings would be noteworthy when using Qvar for Japanese patients with asthma known to have a relatively high frequency of the complication of alcohol-induced asthma.

Eosinophilic inflammation, remodeling of lower airway, bronchial responsiveness and cough reflex sensitivity in non-asthmatic subjects with nasal allergy.

BACKGROUND: It has been reported that nasal allergy influences the lower airway inflammation and functions. We elucidated whether nasal allergy would contribute to lower airway inflammation and functions. METHODS: 266 subjects aged 21-39 years were interviewed with special emphasis on history of asthma and nasal allergies (perennial allergic rhinitis (PAR) and seasonal allergic rhinitis (Japanese cedar pollinosis; PO)). Symptomatic subject was defined when nasal symptoms were present during a 3-week study period. Pulmonary function, provocative concentration of methacholine causing a 20% fall in forced expiratory volume in 1 s (PC20), capsaicin cough threshold defined as capsaicin concentration eliciting 5 or more coughs (C5) and eosinophil percentage in hypertonic saline-induced sputum were measured. RESULTS: Based on the interview, 232 subjects without asthma were divided into symptomatic (n = 25) and asymptomatic (n = 22) PAR, PO on-season (n = 15) and off-season (n = 36), and non-nasal allergy subjects (control) (n = 134). Sputum eosinophils were significantly greater in symptomatic PAR than another four groups (p < 0.01). FEV1/FVC ratio was significantly lower in PAR than control (p < 0.05). Maximum mean expiratory flow was lower in PAR than control (asymptomatic: p < 0.05, symptomatic: p = 0.06). C5 was not different among groups. PAR tended to have a lower PC20 compared to control (symptomatic: p = 0.078; asymptomatic: p = 0.086). CONCLUSIONS: These results suggest that eosinophilic inflammation occurred in symptomatic period of PAR may contribute to development of lower airway remodeling and bronchial hyperresponsiveness. Reversely, PO may not be associated with lower airway eosinophilic inflammation or abnormal bronchial functions. Nasal allergy dose not influence the cough reflex sensitivity.

Asthma severity is associated with an increase in both blood CXCR3+ and CCR4+ T cells.

OBJECTIVES: A predominance of type 2 helper T cells (Th2) in the bronchoalveolar space and peripheral blood is a well-accepted feature of bronchial asthma. However, the relationship between peripheral blood Th2 cells and asthma severity has not been thoroughly investigated. METHODS: As Th1 cells predominantly express the chemokine receptor CXCR3 and Th2 cells express CCR4, we assessed the distribution of peripheral blood CXCR3+ and CCR4+ lymphocytes using flow cytometry in 186 patients with asthma and 75 normal subjects. RESULTS: The proportion of CXCR3+/CD45RO+ cells in CD4+ T cells increased as the severity of asthma increased. The percentage of CCR4+/CD45RO+ cells in CD4+ T cells were elevated in mild to severe asthma patients compared with controls. However, there was no significant difference in CCR4+/CD45RO+ cells between the mild to severe asthma patients. There was no relationship between the patient's age and the numbers of CXCR3+ or CCR4+ T cells. The percentage of CCR4+ cells in CD45RO+/CD4+ T cells correlated with the levels of total serum IgE (r = 0.630, P < 0.0001). CONCLUSIONS: The proportion of CCR4+ cells in blood memory helper T cells may be increased in patients with asthma and is associated with the level of serum IgE, but severity of asthma is also associated with the increase of blood CXCR3+ cells in memory helper T cells.

A case of acute hypersensitivity pneumonitis associated with an oil fan heater.

We report here a case of acute hypersensitivity pneumonitis induced by an oil fan heater. A 57-year-old man was admitted to our hospital because of fever, nonproductive cough, and dyspnea. Paeccilomyces variotii and Paeccilomyces nivea were identified from an oil fan heater in his house. The result of an environmental challenge test was positive. Intradermal reaction and precipitin results to sugar antigen of those fungi were positive only in the patient. This is the first described case of acute hypersensitivity pneumonitis caused by an oil fan heater.

Phosphodiesterase 3 inhibition and cough in elderly asthmatics.

AIMS: Cough is a common symptom of bronchial asthma, a chronic inflammatory airway disease. Recently, the therapeutic effects of selective phosphodiesterase (PDE) inhibitors have been focused on bronchial asthma. This study was designed to investigate the clinical effect of PDE 3 inhibition on cough reflex sensitivity in elderly patients with bronchial asthma. METHODS: Effects of cilostazol, a PDE 3 inhibitor, on cough response to inhaled capsaicin were examined in 11 patients over 70 years with stable asthma in a randomized, placebo-controlled cross over study. Capsaicin cough threshold, defined as the lowest concentration of capsaicin eliciting five or more coughs, was measured as an index of airway cough reflex sensitivity. RESULTS: The cough threshold was significantly (p < 0.05) increased after two-week treatment with cilostazol (100 mg twice a day orally) compared with placebo [48.8 (GSEM 1.4) vs. 29.2 (GSEM 1.3) muM]. CONCLUSION: These findings indicate that PDE 3 inhibition may be a novel therapeutic option for elderly patients with asthma, especially for their cough symptoms.

Primary alveolar hypoventilation syndrome complicated with antiphospholipid syndrome.

A 32-year-old woman was transported to our hospital by ambulance because of loss of consciousness and breathing induced by drug intoxication. After general status was recovered, her arterial blood gas analysis under breathing room air revealed hypercapnia and hypoxemia which were caused by hypoventilation. After exclusion of apparent pulmonary, neuromuscular and central nerve diseases, she was diagnosed with primary alveolar hypoventilation syndrome. She had the complication of antiphospholipid syndrome (APS), suggesting the possibility of small lesions of the brainstem due to APS, which were too small to be detected on CT or MRI; these small lesions could cause injuries to the respiratory center.

Change in bronchial responsiveness and cough reflex sensitivity in patients with cough variant asthma: effect of inhaled corticosteroids.

BACKGROUND: Cough variant asthma (CVA) is a cause of chronic cough and a precursor of typical asthma. We retrospectively examined the longitudinal change in bronchial responsiveness and cough reflex sensitivity in CVA patients with respect to the effect of long-term inhaled corticosteroids (ICS). METHODS: Provocative concentration of methacholine causing a 20% fall in forced expiratory volume in one second (PC20-FEV1) and provocative concentration of capsaicin eliciting 5 or more coughs (C5) were measured before treatment and during a follow up period following relief of cough (median; 2.0 (range; 0.5 to 8.0) years after the initial visit) in a total of 20 patients with CVA (7 males and 13 females, mean +/- SD age of 49.9 +/- 12.9 years). RESULTS: Three of 8 patients not taking long-term ICS developed typical asthma compared to none of 12 patients taking ICS (p = 0.0171). PC20-FEV1 significantly (p < 0.0001) increased from 1.80 (GSEM, 1.35) to 10.7 (GSEM, 1.63) mg/ml in patients taking ICS but did not change in patients not taking ICS [2.10 (GSEM, 1.47) compared to 2.13 (GSEM, 1.52) mg/ml]. Cough threshold did not change in patients whether taking or not taking ICS. CONCLUSION: Long-term ICS reduces bronchial hyperresponsiveness in CVA as recognized in typical asthma. Cough reflex sensitivity is not involved in the mechanism of cough in CVA.

Comparison of cough reflex sensitivity after an inhaled antigen challenge between actively and passively sensitized guinea pigs.

BACKGROUND: Late asthmatic response is observed following antigen challenge in actively, but not passively, sensitized guinea pigs. Although cough reflex sensitivity is increased after antigen challenge in actively sensitized guinea pigs, it is unknown whether the antigen-induced increase in cough reflex sensitivity develops in passively sensitized animals. The aim of this study was to compare the cough reflex sensitivity to inhaled capsaicin after an inhaled antigen challenge between actively and passively sensitized guinea pigs. METHODS: Measurement of number of coughs elicited by increasing concentrations of capsaicin (10(-6) and 10(-4) M) and bronchial responsiveness to ascending concentrations of methacholine, and analysis of bronchoalveolar lavage fluid (BALF) were separately performed 24 h after an antigen challenge in actively and passively sensitized guinea pigs. RESULTS: Percentage of eosinophils in BALF and bronchial responsiveness to methacholine were increased 24 h after the antigen challenge in both actively and passively sensitized animals compared with saline-challenged actively and passively sensitized animals, respectively. Absolute number of eosinophils in BALF from actively sensitized and antigen-challenged guinea pigs was significantly greater than that from passively sensitized and antigen-challenged animals. Cough response to capsaicin and concentration of substance P in BALF were increased 24 h after the antigen challenge in actively sensitized guinea pigs, but not in passively sensitized guinea pigs. Bronchial responsiveness, cough reflex sensitivity and substance P concentration and total cells in BALF were increased in actively sensitized and saline challenged guinea pigs compared with passively sensitized and saline challenged animals. CONCLUSION: The results suggest that active sensitization per se increases cough reflex sensitivity accompanied by increased inflammatory cells and substance P level in BALF, and antigen challenge further increases them, while simple IgE- and/or IgG-mediated allergic reaction per se or the low intensity of eosinophil infiltration in the airway itself may not affect cough reflex sensitivity in guinea pigs.

Regulation of interleukin-5-induced beta2-integrin adhesion of human eosinophils by phosphoinositide 3-kinase.

We examined the role of phosphoinositide 3-kinase (PI3K) in integrin-mediated eosinophil adhesion. Deltap85, a dominant-negative form of the class IA PI3K adaptor subunit, was fused to an HIV-TAT protein transduction domain (TAT-Deltap85). Recombinant TAT-Deltap85 inhibited interleukin (IL)-5-stimulated phosphorylation of protein kinase B, a downstream target of PI3K. beta(2)-Integrin-dependent adhesion caused by IL-5 to the plated intracellular adhesion molecule-1 surrogate, bovine serum albumin, was inhibited by TAT-Deltap85 in a concentration-dependent manner. Similarly, two PI3K inhibitors, wortmannin and LY294002, blocked eosinophil adhesion to plated bovine serum albumin. By contrast, beta(1)-integrin-mediated eosinophil adhesion to vascular cell adhesion moelcule-1 was not blocked by TAT-Deltap85, wortmannin, or LY294002. Rottlerin, a protein kinase C (PKC)-delta inhibitor, also blocked beta(2)-integrin adhesion of eosinophils caused by IL-5, whereas beta(1) adhesion to vascular cell adhesion molecule-1 was not affected. IL-5 caused translocation of PKCdelta from the cytosol to cell membrane; inhibition of PI3K by wortmannin blocked translocation of PKCdelta. Western blot analysis demonstrated that extracellular signal-regulated kinase phosphorylation, a critical intermediary in adhesion elicited by IL-5, was blocked by inhibition of either PI3K or PKC-delta. These data suggest that extracellular signal-regulated kinase-mediated adhesion of beta(2)-integrin caused by IL-5 is mediated in human eosinophils by a class IA PI3K through activation of a PKCdelta pathway.

In vivo PAF-induced airway eosinophil accumulation reduces bronchial responsiveness to inhaled histamine.

Chronic eosinophilic bronchitis and bronchial hyperresponsiveness have been considered to be the fundamental features of bronchial asthma. However, the role of airway eosinophils in bronchial responsiveness in vivo has not been fully discussed. The aim of this study was to investigate the direct effect of airway eosinophil accumulation on bronchial responsiveness in vivo. Guinea pigs were transnasally treated with platelet activating factor (PAF) or vehicle twice a week for a total of 3 weeks. Anesthetized guinea pigs were surgically cannulated and artificially ventilated 48 h after the last administration of PAF or vehicle. Ten minutes after the installation of artificial ventilation, ascending doses of histamine were inhaled. In a subsequent study, selective inhibitors of diamine oxidase and histamine N-methyltransferase were intravenously administered before the histamine inhalation in the PAF-treated animals. Next study was conducted 20 min after treatment with indomethacin in this study line. Finally, ascending doses of methacholine were inhaled in our animal model. Proportion of eosinophils and the number of nuclear segmentation in bronchoalveolar lavage fluid significantly increased in guinea pigs treated with PAF compared with vehicle and this finding was confirmed histologically. Nevertheless, bronchial responsiveness to inhaled histamine, but not methacholine, was significantly decreased by the PAF treatment. This bronchoprotective effect induced by PAF remained following aminoguanidine and histamine N-methyltransferase administration, but abolished by treatment of indomethacin. These results suggest that in vivo airway eosinophils may reduce nonspecific bronchial responsiveness through production of inhibitory or bronchoprotective prostanoids, but not through histaminase production.