Search

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) μM] compared with placebo [30.3 (GSEM 1.21) μM]. 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. [ABSTRACT FROM AUTHOR]

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. Copyright © 2006 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Summary We examined the role of cell surface clustering of β2 -integrin caused by protein kinase C (PKC)-activated-cPLA2 in adhesion of eosinophilic AML14.3D10 (AML) cells. Phorbol 12-myristate 13-acetate (PMA) caused time- and concentration-dependent adhesion of AML cells to plated bovine serum albumin (BSA), which was blocked by anti-CD11b or anti-CD18 monoclonal antibodies (mAb) directed against β2 -integrin. Inhibition of PKC with Ro-31-8220 or rottlerin blocked PMA-induced cell adhesion in a concentration-dependent fashion. Inhibition of cytosolic phospholipase A2 (cPLA2 ) with trifluoromethyl ketone or methyl arachidonyl fluorophosphonate also blocked PMA-induced cell adhesion. PMA caused time-dependent p42/44 mitogen-activated protein kinase (MAPK) (ERK) phosphorylation in these cells. U0126, a MAPK/extracellular signal-regulated protein kinase kinase (MEK) inhibitor, at the concentrations that blocked PMA-induced ERK phosphorylation, had no effect on PMA stimulated AML cell adhesion. Neither p38 MAPK nor c-Jun N-terminal kinase (JNK) was phosphorylated by PMA. PMA also caused increased cPLA2 activity, which was inhibited by Ro-31-8220, but not U0126. Confocal immunofluorescence microscopy showed that PMA caused clustering of CD11b on the cell surface, which was blocked by either PKC or cPLA2 inhibition. PMA stimulation also caused up-regulation of CD11b on the AML cell surface. However, this up-regulation was not affected by cPLA2 - or PKC-inhibition. Using the mAb, CBRM1/5, we also demonstrated that PMA does not induce the active conformation of CD11b/CD18. Our data indicate that PMA causes AML cell adhesion through β2 -integrin by PKC activation of cPLA2 . This pathway is independent of MEK/ERK and does not require change of CD11b/CD18 to its active conformation. We find that avidity caused by integrin surface clustering –... [ABSTRACT FROM AUTHOR]

Summary We examined the role of cell surface clustering of β2 -integrin caused by protein kinase C (PKC)-activated-cPLA2 in adhesion of eosinophilic AML14.3D10 (AML) cells. Phorbol 12-myristate 13-acetate (PMA) caused time- and concentration-dependent adhesion of AML cells to plated bovine serum albumin (BSA), which was blocked by anti-CD11b or anti-CD18 monoclonal antibodies (mAb) directed against β2 -integrin. Inhibition of PKC with Ro-31-8220 or rottlerin blocked PMA-induced cell adhesion in a concentration-dependent fashion. Inhibition of cytosolic phospholipase A2 (cPLA2 ) with trifluoromethyl ketone or methyl arachidonyl fluorophosphonate also blocked PMA-induced cell adhesion. PMA caused time-dependent p42/44 mitogen-activated protein kinase (MAPK) (ERK) phosphorylation in these cells. U0126, a MAPK/extracellular signal-regulated protein kinase kinase (MEK) inhibitor, at the concentrations that blocked PMA-induced ERK phosphorylation, had no effect on PMA stimulated AML cell adhesion. Neither p38 MAPK nor c-Jun N-terminal kinase (JNK) was phosphorylated by PMA. PMA also caused increased cPLA2 activity, which was inhibited by Ro-31-8220, but not U0126. Confocal immunofluorescence microscopy showed that PMA caused clustering of CD11b on the cell surface, which was blocked by either PKC or cPLA2 inhibition. PMA stimulation also caused up-regulation of CD11b on the AML cell surface. However, this up-regulation was not affected by cPLA2 - or PKC-inhibition. Using the mAb, CBRM1/5, we also demonstrated that PMA does not induce the active conformation of CD11b/CD18. Our data indicate that PMA causes AML cell adhesion through β2 -integrin by PKC activation of cPLA2 . This pathway is independent of MEK/ERK and does not require change of CD11b/CD18 to its active conformation. We find that avidity caused by integrin surface clustering –... [ABSTRACT FROM AUTHOR]

We examined the role of a cytosolic phospholipase A2 (cPLA2) in antigen-induced eosinophil infiltration of airways and in airway hyperresponsiveness to methacholine. Inhibition of cPLA2, or blockade of the platelet-activating factor (PAF) receptor, blocked antigen-induced airway hyperresponsiveness and suppressed eosinophil infiltration. Neither cyclooxygenase nor 5-lipoxygenase inhibition had either effect. We show here that, in antigen-sensitized guinea pigs, cPLA2 inhibition prevents both eosinophilic infiltration and subsequent airway hyperresponsiveness after antigen challenge. We also show that this effect is mediated by first-step hydrolysis of membrane phospholipid into lysophospholipid rather than by prostanoid or leukotriene metabolites of arachidonate. [ABSTRACT FROM AUTHOR]

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 (FEV 1 ). Qvar contains beclomethasone dipropionate combined with absolute ethanol and an alternative to fluorocarbon. The patient had complicated alcohol-induced asthma. FEV 1 decreased markedly and immediately after Qvar inhalation. The Qvar placebo is free of beclomethasone but contains other ingredients (ethanol and fluorocarbon). FEV 1 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 FEV 1 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. [ABSTRACT FROM AUTHOR]

We investigated the effect and mechanism(s) of PDE-4 treatment with concurrent β2-adrenoceptor stimulation on human eosinophil adhesion mediated by β2-integrin in vitro. Eosinophils were pretreated with either rolipram, a PDE-4 inhibitor, alone or combined with salmeterol, a β2-adrenoceptor agonist, before activation with either eotaxin or IL-5. β2-integrin mediated adhesion was assessed as adherence to BSA, an established surrogate for ICAM-1. Rolipram caused progressive blockade (77.7±6.2%) of adhesion elicited by eotaxin. Maximal blockade of IL-5-activated adhesion by rolipram was substantially less (29.9±5.2%). Salmeterol+rolipram synergistically enhanced the blockade of eotaxin-activated adhesion. Eotaxin also caused ∼50% increase in surface CD11b expression, which was blocked additively by rolipram+salmeterol. By contrast, CD11b upregulation caused by IL-5 was not blocked by rolipram+salmeterol. Rolipram also attenuated cPLA2 phosphorylation caused by eotaxin but did not block IL-5-induced phosphorylation. We conclude that rolipram blocks expression of CD11b and inhibits cPLA2 phosphorylation in human eosinophils, thus blocking eotaxin-induced adhesion of β2-integrin. IL-5-induced adhesion likely utilizes a different upstream mechanism in regulation of integrin adhesion. [Copyright &y& Elsevier]

We previously reported that exogenously added human group V phospholipase A[sub 2] (hVPLA[sub 2]) could elicit leukotriene B[sub 4] biosynthesis in human neutrophils through the activation of group IVA phospholipase A[sub 2] (cPLA[sub 2]) (Kim, Y. J., Kim, K. P., Han, S. K., Munoz, N. M., Zhu, X., Sano, H., Leff, A. R., and Cho, W. (2002) J. Biol. Chem. 277, 36479-36488). In this study, we determined the functional significance and mechanism of the exogenous hVPLA[sub 2]-induced arachidonic acid (AA) release and leukotriene C[sub 4] (LTC[sub 4]) synthesis in isolated human peripheral blood eosinophils. As low a concentration as 10 nM exogenous hVPLA[sub 2] was able to elicit the significant release of AA and LTC[sub 4] from unstimulated eosinophils, which depended on its ability to act on phosphatidylcholine membranes, hVPLA[sub 2] also augmented the release of AA and LTC[sub 4] from eosinophils activated with formyl-Met-Leu-Phe + cytochalasin B. A cellular fluorescent PLA[sub 2] assay showed that hVPLA[sub 2] had a lipolytic action first on the outer plasma membrane and then on the perinuclear region, hVPLA[sub 2] also caused the translocation of 5-lipoxygenase from the cytosol to the nuclear membrane and a 2-fold increase in 5-1ipoxygenase activity. However, hVPLA[sub 2] induced neither the increase in intracellular calcium concentration nor cPLA[sub 2] phosphorylation; consequently, cPLA[sub 2] activity was not affected by hVPLA[sub 2]. Pharmacological inhibition of cPLA[sub 2] and the hVPLA[sub 2]-induced activation of eosinophils derived from the cPLA[sub 2]-deficient mouse corroborated that hVPLA[sub 2] mediates the release of AA and leukotriene in a cPLA[sub 2]-independent manner. As such, this study represents a unique example in which a secretory phospholipase induces the eicosanoid formation in inflammatory cells, completely independent of cPLA[sub 2] activation. [ABSTRACT FROM AUTHOR]

α-Adrenoceptors have been classified into α1- and α2-adrenoceptors. Recently, the α1-adrenoceptors were divided into two subtypes: α1L with low affinity and α1H with high affinity for prazosin. Little is known concerning the role of each subtype of α1-adrenoceptor in asthma. We investigated the effects of specific antagonists of α1- and α2-, α1H-, α1L-, and α2-adrenoceptors, namely moxisylyte, prazosin, 3-{N-[2-(4-hydroxy-2-isopropyl-5-methylphenoxy) ethyl]-N-methylaminomethyl}-4-methoxy-2, 5, 6-trimethylphenol hemifumarate (JTH-601), and yohimbine, respectively, on antigen-induced airway reactions in guinea pigs. Fifteen minutes after intravenous administration of moxisylyte (0.01, 0.1 or 1 mg/kg), prazosin (0.01, 0.1, 1 or 10 mg/kg), JTH-601 (1, 3, 6 or 10 mg/kg) or yohimbine (0.1 or 1 mg/kg), passively sensitized and artificially ventilated animals received an aerosolized antigen challenge. Bronchial responsiveness to inhaled methacholine was assessed as the dose of methacholine required to produce a 200% increase in the pressure at the airway opening (PC200) in non-sensitized animals. JTH-601 and moxisylyte, but not prazosin or yohimbine, dose dependently inhibited antigen-induced bronchoconstriction. None of the tested drugs altered PC200. JTH-601 significantly reduced leukotriene C4 levels in bronchoalveolar lavage fluid obtained 5 min after antigen challenge, but prazosin did not. These results indicate that prevention of antigen-induced bronchoconstriction by blockade of α-adrenoceptors is due to the inhibition of mediator release via α1L-adrenoceptor antagonism. [Copyright &y& Elsevier]

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.

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.

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.

A 24-year old man was hospitalized because of a severe asthmatic attack in August 2003. The asthma attack was well controlled by mechanical ventilation, intravenous hydrocortisone and inhaled beta2-agonist. Physical examination revealed sparse hair, reduced sweating and hypodontia. We also confirmed the absence of sweat glands in a biopsied skin specimen. The diagnosis based on these findings was anhidrotic ectodermal dysplasia A mutation in the EDA (ectodysplasin-A) gene which led to an X-linked anhidrotic ectodermal dysplasia was found, and the same genetic mutation was detected in the patient's mother.

We investigated the effect and mechanism(s) of PDE-4 treatment with concurrent beta2-adrenoceptor stimulation on human eosinophil adhesion mediated by beta2-integrin in vitro. Eosinophils were pretreated with either rolipram, a PDE-4 inhibitor, alone or combined with salmeterol, a beta2-adrenoceptor agonist, before activation with either eotaxin or IL-5. Beta2-integrin mediated adhesion was assessed as adherence to BSA, an established surrogate for ICAM-1. Rolipram caused progressive blockade (77.7 +/- 6.2%) of adhesion elicited by eotaxin. Maximal blockade of IL-5-activated adhesion by rolipram was substantially less (29.9 +/- 5.2%). Salmeterol + rolipram synergistically enhanced the blockade of eotaxin-activated adhesion. Eotaxin also caused approximately 50% increase in surface CD11b expression, which was blocked additively by rolipram + salmeterol. By contrast, CD11b upregulation caused by IL-5 was not blocked by rolipram + salmeterol. Rolipram also attenuated cPLA2 phosphorylation caused by eotaxin but did not block IL-5-induced phosphorylation. We conclude that rolipram blocks expression of CD11b and inhibits cPLA2 phosphorylation in human eosinophils, thus blocking eotaxin-induced adhesion of beta2-integrin. IL-5-induced adhesion likely utilizes a different upstream mechanism in regulation of integrin adhesion.

Background: Increased numbers of eosinophils in the airways is characteristic of asthma. However, it remains unclear whether airway eosinophils enhance or reduce the release of neuropeptides in the airways in vivo. This study was conducted to elucidate the influence of airway eosinophil accumulation on the ultrasonically nebulized distilled water (UNDW)-induced bronchoconstriction in our newly developed animal model, which is mediated by sensory neuropeptides., Methods: Guinea pigs were transnasally treated with 100 mg/kg of platelet activating factor (PAF), or vehicle, twice a week for 3 weeks. We then conducted three experiments. In the first, UNDW was inhaled 20 min after aerosolized antigen challenge, and bronchoalveolar lavage (BAL) was performed in PAF-treated and passively sensitized animals. In the second, PAF-treated animals were exposed for 20 s to ascending doses of methacholine at intervals of 5 min In the third, passively sensitized animals were administered selective NK1 antagonist, SR 140333, selective NK2 antagonist, SR 48968, or vehicle, intravenously 5 min before UNDW-induced bronchoconstriction., Results: The proportion of eosinophils in BAL fluid was significantly increased in guinea pigs treated with PAF, compared with the vehicle. The PAF treatment did not affect antigen-induced immediate asthmatic response, UNDW-induced bronchoconstriction, or bronchial responsiveness to inhaled methacholine. SR 140333, but not SR 48968, inhibited the UNDW-induced bronchoconstriction., Conclusion: We conclude that eosinophils accumulated in the airways, caused by repeated intranasal administration of PAF, does not affect the release of substance P induced by UNDW inhalation, or the action of released substance P in vivo.

We transduced dominant negative (dn) HIV TAT-Ras protein into mature human eosinophils to determine the signaling pathways and mechanism involved in integrin-mediated adhesion caused by cytokine, chemokine, and chemoattractant stimulation. Transduction of TAT-dnRas into nondividing eosinophils inhibited endogenous Ras activation and extracellular signal-regulated kinase (ERK) phosphorylation caused by IL-5, eotaxin-1, and fMLP. IL-5, eotaxin-1, or fMLP caused 1) change of Mac-1 to its active conformation and 2) focal clustering of Mac-1 on the eosinophil surface. TAT-dnRas or PD98059, a pharmacological mitogen-activated protein/ERK kinase inhibitor, blocked both focal surface clustering of Mac-1 and the change to active conformational structure of this integrin assessed by the mAb CBRM1/5, which binds the activation epitope. Eosinophil adhesion to the endothelial ligand ICAM-1 was correspondingly blocked by TAT-dnRas and PD98059. As a further control, we used PMA, which activates ERK phosphorylation by postmembrane receptor induction of protein kinase C, a mechanism which bypasses Ras. Neither TAT-dnRas nor PD98059 blocked eosinophil adhesion to ICAM-1, up-regulation of CBRM1/5, or focal surface clustering of Mac-1 caused by PMA. In contrast to beta(2)-integrin adhesion, neither TAT-dnRas nor PD98059 blocked the eosinophil adhesion to VCAM-1. Thus, a substantially different signaling mechanism was identified for beta(1)-integrin adhesion. We conclude that H-Ras-mediated activation of ERK is critical for beta(2)-integrin adhesion and that Ras-protein functions as the common regulator for cytokine-, chemokine-, and G-protein-coupled receptors in human eosinophils.

We examined the role of cell surface clustering of beta2-integrin caused by protein kinase C (PKC)-activated-cPLA2 in adhesion of eosinophilic AML14.3D10 (AML) cells. Phorbol 12-myristate 13-acetate (PMA) caused time- and concentration-dependent adhesion of AML cells to plated bovine serum albumin (BSA), which was blocked by anti-CD11b or anti-CD18 monoclonal antibodies (mAb) directed against beta2-integrin. Inhibition of PKC with Ro-31-8220 or rottlerin blocked PMA-induced cell adhesion in a concentration-dependent fashion. Inhibition of cytosolic phospholipase A2 (cPLA2) with trifluoromethyl ketone or methyl arachidonyl fluorophosphonate also blocked PMA-induced cell adhesion. PMA caused time-dependent p42/44 mitogen-activated protein kinase (MAPK) (ERK) phosphorylation in these cells. U0126, a MAPK/extracellular signal-regulated protein kinase kinase (MEK) inhibitor, at the concentrations that blocked PMA-induced ERK phosphorylation, had no effect on PMA stimulated AML cell adhesion. Neither p38 MAPK nor c-Jun N-terminal kinase (JNK) was phosphorylated by PMA. PMA also caused increased cPLA2 activity, which was inhibited by Ro-31-8220, but not U0126. Confocal immunofluorescence microscopy showed that PMA caused clustering of CD11b on the cell surface, which was blocked by either PKC or cPLA2 inhibition. PMA stimulation also caused up-regulation of CD11b on the AML cell surface. However, this up-regulation was not affected by cPLA2- or PKC-inhibition. Using the mAb, CBRM1/5, we also demonstrated that PMA does not induce the active conformation of CD11b/CD18. Our data indicate that PMA causes AML cell adhesion through beta2-integrin by PKC activation of cPLA2. This pathway is independent of MEK/ERK and does not require change of CD11b/CD18 to its active conformation. We find that avidity caused by integrin surface clustering - rather than conformational change or up-regulation of CD11b/CD18 - causes PMA stimulated adhesion of AML cells.