Role of superoxide anions in airway hyperresponsiveness induced by cigarette smoke in conscious guinea pigs

To investigate the involvement of superoxide in airway hyperresponsiveness and bronchoconstriction induced by cigarette smoke (CS), we evaluated the effects of superoxide dismutase (SOD), a scavenger of superoxide anion, and apocynin, an inhibitor of superoxide anion-generating NADPH oxidase in phagocytes, on the airway responses induced by CS in conscious guinea pigs. Airway responsiveness was assessed by PC200Mch, the concentration required to produce a doubling in the baseline specific airway resistance (sRaw) to an inhaled methacholine aerosol, in nonanesthetized spontaneously breathing animals. Before being exposed to ten puffs of CS, animals inhaled either SOD (5,000 units/ml or 25,000 units/ml) or vehicle. Although SOD did not affect PC200Mch in the air control group, this agent significantly reduced the CS-induced airway hyperresponsiveness. Repeated administration of apocynin (12 mg/kg for 4 days) did not affect PC200Mch after exposure to CS. These data suggest that the superoxide from CS was involved in the airway hyperresponsiveness induced by CS, whereas phagocytic reactive oxygen species were not. The data also suggest a potential therapeutic role for antioxidants in airway hyperresponsiveness.     

Persistent airway hyperresponsiveness and histologic alterations after chronic antigen challenge in cats

We studied the effect of chronic immune sensitization on the airway reactivity and associated cytologic and histologic alterations in initially nonatopic cats, a species that spontaneously develops idiopathic asthma. Seven cats were sensitized by intramuscular injection of Ascaris suum antigen (AA) for 4 wk, and four other cats served as sham controls. Airway sensitization was demonstrated by an increased response to nebulized AA in sensitized animals (RL = 45.9 +/- 6.1 cm H2O/L/s, versus a baseline response of 24.7 +/- 1.5 cm H2O/L/s, p < 0.01), and hyperresponsiveness was demonstrated by an increased response to acetylcholine (ACh)-challenge 24 h after AA (approximately 1.0 log decrease in PD200, p < 0.01). The number of eosinophils in the sensitized animals' bronchoalveolar lavage (BAL) fluid increased 12-fold (p < 0.01 versus control) in response to AA challenge; 32 +/- 5% of the BAL eosinophils had a specific density < 1.050, versus 8 +/- 2% prior to AA challenge (p < 0.05). There was no change in airway reactivity, eosinophil recovery, or density in the control group 24 h after sham challenge with saline. The same seven sensitized cats further received nebulized AA three times weekly for 4 to 6 wk, after which BAL samples were again obtained and ACh dose-response curves generated 72 h after the final administration of nebulized AA. Airway hyperresponsiveness increased (approximately 1.5 log decrease in PD200, p < 0.001) and the number of eosinophils recovered in BAL fluid was increased 11-fold (p < 0.05). Necropsy specimens demonstrated bronchoconstriction in AA-challenged animals but not controls; luminal narrowing was accompanied by: (1) a 29.0 +/- 0.34% increase in smooth-muscle thickness (p < 0.05); (2) goblet-cell and submucosal-gland hypertrophy and hyperplasia; and (3) epithelial erosion and eosinophilic infiltration. We demonstrate in nonhuman species persistent airway hyperreactivity associated with a complete constellation of histologic changes in epithelium, smooth muscle, and mucus glands, and cytologic changes in BAL fluid, all induced by immune sensitization. Our data suggest that chronic immune sensitization per se could be a salient factor in causing many of the changes associated with chronic bronchial asthma.     

Acute exposure to hair bleach causes airway hyperresponsiveness in a rabbit model

Ammonium persulphate (APS) and hydrogen peroxide (H2O2) are used as oxidants in many industrial processes and are the main constituents of standard hair bleaching products. In a previous study, it was demonstrated that aerosols of APS induce alterations in airway responsiveness. The present study examined whether exposure for 4 h to a hair bleach composition (containing APS, potassium persulphate and H2O2) or H2O2 could induce airway hyperresponsiveness and/or an obstructive ventilation pattern in a rabbit model. Exposure to the aerosols altered neither baseline airway resistance, dynamic elastance, slope of inspiratory pressure generation nor arterial blood pressure and blood gas measurements. Similarly to APS, hair bleach aerosols containing > or =10.9 mg x m(-3) persulphate (ammonium and potassium salt) in air and > or =1.36 mg x m(-3) H2O2 in air caused airway hyperresponsiveness to acetylcholine after 4 h of exposure. Aerosolized H2O2 (> or =37 mg x m(-3) in air) did not influence airway responsiveness to acetylcholine. The results demonstrate that hair bleaching products containing persulphates dissolved in H2O2 cause airway hyperresponsiveness to acetylcholine in rabbits.     

Late asthmatic response causes peripheral airway hyperresponsiveness in dogs treated with metopirone

To determine if late asthmatic response (LAR) is associated with hyperresponsiveness of airway smooth muscle itself, we performed antigen challenge in dogs treated with Metopirone. We studied the contractile response to acetylcholine (ACh) in isolated bronchial and bronchiolar segments 8 h after either saline inhalation (the control group) or antigen challenge in dogs demonstrating immediate asthmatic response (IAR) alone and in dogs demonstrating both IAR and LAR. Airway responses to Ascaris suum antigen were assessed by changes in respiratory resistance measured with the forced oscillation technique at 3 Hz. Concentration-response curves of bronchial preparations to ACh did not differ significantly among three groups consisting of the control, IAR and LAR. However, the contractile response of bronchiolar preparations to ACh was significantly greater in the LAR group when compared to the control and IAR groups at the concentrations of ACh ranging from 10(-6) to 3 x 10(-4) M (p < 0.01). SQ 29548, a receptor antagonist of thromboxane A2 and prostaglandin D2 (PGD2), inhibited LAR-induced hyperresponsiveness to ACh in a concentration-dependent fashion. The bronchiolar preparations obtained from dogs showing LAR contained a significantly higher amount of PGD2 than those obtained from dogs showing IAR alone (p < 0.01, n = 6). These results suggest that LAR is associated with hyperresponsiveness of peripheral airway smooth muscle to ACh, and this augmented response to ACh mediates via PGD2 released during LAR.     

Angiotensin-converting enzyme inhibitors can potentiate ozone-induced airway hyperresponsiveness

We investigated the effects of single and chronic oral administration of angiotensin-converting enzyme inhibitors on ozone-induced airway hyperresponsiveness in guinea pigs. Ozone exposure (3 ppm for 2 h) significantly increased airway responsiveness in vehicle-treated animals and in animals with either single or chronic administration (8 days) of drugs. Single administration of imidapril, enalapril and captopril significantly potentiated ozone-induced airway hyperresponsiveness at a dose of 100, 50 and 50 mg/kg, respectively, although these doses did not influence airway responsiveness in normal guinea pigs, i.e., the magnitude of potentiation was captopril > enalapril > imidapril. In the study of chronic administration of the drugs, imidapril (10-100 mg/kg per day) had no influence on airway responsiveness in both normal and ozone-treated animals. In contrast, captopril and enalapril (10-100 mg/kg per day) dose-dependently potentiated ozone-induced airway hyperresponsiveness, with no influence on airway responsiveness in normal animals. That is, the magnitude was enalapril > captopril. These results indicate that angiotensin-converting enzyme inhibitors potentiate airway responsiveness in ozone-treated guinea pigs but not in normal guinea pigs and that imidapril is less potent than enalapril and captopril in potentiating ozone-induced airway hyperresponsiveness in guinea pigs.     

Thromboxane causes airway hyperresponsiveness after cigarette smoke-induced neurogenic inflammation

We investigated the role of neurogenic inflammation and the subsequent mechanisms in cigarette smoke-induced airway hyperresponsiveness in guinea pigs. Exposure to cigarette smoke was carried out at tidal volume for 3 min. Airway responsiveness to histamine was determined before and after smoke exposure followed by bronchoalveolar lavage (BAL). Plasma extravasation was evaluated by measuring the extravasation of Evans blue dye in the airway. Cigarette smoke produced significant airway hyperresponsiveness and plasma extravasation, with an influx of neutrophils in BAL fluid. FK-224 (10 mg/kg i.v.), a tachykinin antagonist at NK1 and NK2 receptors, significantly inhibited these changes. The thromboxane (Tx) B2 concentration was increased in BAL fluid after smoke exposure and was significantly inhibited by FK-224. OKY-046 (10 mg/kg i.v.), a Tx synthase inhibitor, significantly inhibited airway hyperresponsiveness but had no effect on neutrophil influx or plasma extravasation. The results suggest that neurogenic inflammation and the subsequent generation of Tx in the airway are important in the development of the airway hyperresponsiveness induced by cigarette smoke.     

Oral administration of L-arginine potentiates allergen-induced airway inflammation and expression of interleukin-5 in mice

The role of nitric oxide in the airway hyperresponsiveness and inflammation of bronchial asthma has not yet been established. However, L-arginine, the substrate for nitric oxide synthases, reportedly alleviates airway hyperresponsiveness caused by parainfluenza virus and reduces granulocytic inflammation induced by ischemia-reperfusion. We investigated the effects of L-arginine on a murine model of allergic asthma that included airway hyperresponsiveness, eosinophilic inflammation and expression of interleukin (IL)-5 in the lung. The mice received drinking water with or without L-arginine for 9 weeks. Histologic evaluation and cellular profiles in bronchoalveolar lavage fluid showed that p.o. administration of L-arginine (72 micromol/kg/day) significantly enhanced eosinophilic airway inflammation and goblet cell proliferation that were associated with intratracheal instillation of ovalbumin. L-Arginine also increased protein levels of IL-5 and IL-2 in supernatants from the lung exposed to ovalbumin. The number of eosinophils in bronchoalveolar lavage fluid correlated significantly with the expression of IL-5. L-Arginine did not reverse ovalbumin-associated airway hyperresponsiveness to inhaled ACh. These results suggest that p.o. administration of L-arginine aggravates allergen-induced eosinophilic airway inflammation via expression of IL-5, and in this model it does not show therapeutic efficacy against airway hyperresponsiveness associated with allergen exposure. Oral administration of L-arginine, the precursor of nitric oxide, may not be an effective intervention in allergic asthma.     

Effect of short and long-term exposure to diesel exhaust on sensitivity of guinea pig tracheal preparation to histamine

Single exposure, to diesel exhaust (1 part exhaust diluted by 5 parts of clean air) reduced EC50 of histamine indicating hyperresponsiveness of the receptors in trachea of exposed guinea pigs. In contrast, following repeated exposure for 7, 14 or 21 days (15 min/day), EC50 was progressively increased indicating the possibility of down-regulated histamine receptors. Further, simultaneous significant increase in histamine levels (bioassayed on guinea pig ileum) in bronchial airway lavage fluid supports the aforementioned hypothesis. The change in lung/body weight ratio and suspended particulate matter deposited on filters followed the same temporal pattern as EC50. The findings are suggestive of differential effects of diesel exhaust on airway depending upon the duration of exposure.     

CD4+ T cells can induce airway hyperresponsiveness to allergen challenge in the brown norway rat

Airway hyperresponsiveness to inhalational challenge with methacholine (MCh) develops by 32 h after allergen challenge of actively sensitized BN rats. To test the hypothesis that CD4+ T cells mediate allergen-induced hyperresponsiveness independent of IgE-mediated mechanisms, we administered CD4+ T cells, CD8+ T cells, and a mixture of CD4+ and CD8+ T cells (total T cells) isolated from the cervical lymph nodes of rats sensitized with ovalbumin (OA) to naive BN rats that underwent aerosol challenge with either OA or bovine serum albumin (BSA) 2 d later. Responsiveness to MCh was measured 2 d before transfer of T cells and 32 h after challenge with OA or BSA. Airway responsiveness increased significantly in recipients of CD4+ T cells after OA challenge, but not in any other of the treatment groups. Analysis of bronchoalveolar lavage (BAL) cells for major basic protein expression by immunostaining showed eosinophilia in OA-challenged CD4+ and total T-cell recipients. Cells retrieved by bronchoalveolar lavage showed increased expression of IL-5 mRNA (in situ hybridization) in CD4+ T cell recipients after OA challenge compared with other groups. Interferon-gamma mRNA was expressed to the greatest extent in CD8+ recipients, but it was elevated in both OA- and BSA-challenged animals. We conclude that CD4+ T cells can induce airway hyperresponsiveness after inhalational challenge with allergen and this is associated with IL-5 production and eosinophilia. CD8+ T cells may have a negative regulatory effect on responsiveness, possibly mediated by interferon-gamma.     

Pulmonary host defense responses to inhalation of sulfuric acid and ozone

The effects of simultaneous exposure to ozone (O3) and sulfuric acid [H2SO4, 0.23 microns volume median diameter (VMD)] and a single exposure to ultrafine (less than 0.1 micron VMD) H2SO4 under various conditions were studied using the infectivity/mortality and the ciliary beating frequency model systems. A 3-h exposure to a combined aerosol of 196 micrograms O3/m3 and 483 or 241 micrograms H2SO4/m3 significantly increased the susceptibility of mice to a laboratory-induced respiratory infection. However, exposure to 543 micrograms ultrafine H2SO4/m3 for 2 h or 365 micrograms/m3 2 h/d for 5 d did not significantly affect this parameter. Upper airway response, as measured by changes in hamster tracheal ciliary beating frequency, was not affected by either a 3-h combined exposure to 196 micrograms O3/m3 and 847 micrograms H2SO4/m3 or a 2-h exposure to 458 micrograms ultrafine H2SO4/m3.     

Time-course of functional and pathological changes after a single high acute inhalation of chlorine in rats

Reactive airways dysfunction syndrome (RADS) is an asthma-like condition that follows exposure to very high concentrations of an irritant material. We assessed the time-course of pathophysiological alterations in a model of RADS. Sprague-Dawley rats were exposed to 1,500 parts per million (ppm) of chlorine for 5 min. Lung resistance (RL), responsiveness to inhaled methacholine (MCh), the airway epithelium and bronchoalveolar lavage (BAL) were assessed over a 3 month period after exposure. RL increased significantly up to 3 days after exposure, reaching a maximal change of 110+/-16% from baseline. There was a significant decrease in the concentration of MCh required to increase RL by 0.20 cmH2O x mL(-1) x s from days 1-7 after exposure. In some rats, MCh hyperresponsiveness and RL changes persisted after exposure for as long as 1 and 3 months, respectively. Histological evaluation with morphometric evaluation revealed epithelial flattening, necrosis, increase in smooth muscle mass and evidence of epithelial regeneration. BAL showed an increased number of neutrophils. The timing of maximal abnormality in the appearance of the epithelium (days 1-3) corresponded to that of the maximal functional changes. Acute high chlorine exposure results in functional and pathological abnormalities that resolve in the majority of animals after a variable period; however, these changes can persist in some animals. Functional abnormalities in the initial stages may be related to airway epithelial damage.     

Mast cell activation is not required for induction of airway hyperresponsiveness by ozone in mice

Exposure to ambient ozone (O3) is associated with increased exacerbations of asthma. We sought to determine whether mast cell degranulation is induced by in vivo exposure to O3 in mice and whether mast cells play an essential role in the development of pulmonary pathophysiological alterations induced by O3. For this we exposed mast cell-deficient WBB6F1-kitW/kitW-v (kitW/kitW-v) mice and the congenic normal WBB6F1 (+/+) mice to air or to 1 or 3 parts/million O3 for 4 h and studied them at different intervals from 4 to 72 h later. We found evidence of O3-induced cutaneous, as well as bronchial, mast cell degranulation. Polymorphonuclear cell influx into the pulmonary parenchyma was observed after exposure to 1 part/milllion O3 only in mice that possessed mast cells. Airway hyperresponsiveness to intravenous methacholine measured in vivo under pentobarbital anesthesia was observed in both kitW/kitW-v and +/+ mice after exposure to O3. Thus, although mast cells are activated in vivo by O3 and participate in O3-induced polymorphonuclear cell infiltration into the pulmonary parenchyma, they do not participate detectably in the development of O3-induced airway hyperresponsiveness in mice.     

Effect of inhaled cyclosporin A on the allergen-induced late asthmatic response and increased in airway hyperresponsiveness in a guinea pig model of asthma

Oral administration of cyclosporin (CsA), a potent inhibitor of helper T cell function, prevents the allergen-induced late asthmatic response (LAR) and the increase in airway hyperresponsiveness (AH) seen in actively sensitized guinea pigs. The systemic administration of this agent in humans has been associated with serious side effect, therefore, the effects of inhaled CsA were therefore examined in guinea pigs that were actively sensitized by repeated exposure to nebulized ovalbumin. Respiratory resistance (Rrs) of the animals was measured by an oscillation method and the extent of AH was inferred from the inhaled concentration of histamine required to increase Rrs by 200%. The magnitude of ovalbumin-induced immediate bronchoconstriction after sensitization was similar in CsA-treated and nontreated control animals. However, a LAR was observed in 4/5 control animals but in 0/5 CsA-treated animals. The increase in AH observed 24 hours after antigen exposure in control animals was significantly inhibited by prior CsA inhalation. Significant CsA concentrations were detected by radioimmunoassay in the lungs of CsA-treated animals. Thus, inhaled CsA should be further investigated because it may be useful treating asthma while avoiding side effects.     

Bronchial hyperresponsiveness and toluene diisocyanate. Long-term change in sensitized asthmatic subjects

Long-term change in nonspecific and specific bronchial hyperresponsiveness was studied in 16 subjects with asthma induced by toluene diisocyanate (TDI). A significant positive correlation between months of follow-up and provocative dose inducing a 20 percent fall in FEV1 (PD20FEV1) methacholine was observed in 5 of 16 subjects. In 4 of these 5 subjects, a PD20FEV1 > 1 mg of methacholine was observed 30 to 48 months after the end of TDI exposure. In most subjects, nonspecific bronchial hyperresponsiveness did not change. Nine of 16 subjects became nonresponsive to TDI at follow-up examination, but only 3 of these showed a significant increase in PD20FEV1 methacholine. Seven subjects were still responsive to TDI. Recovery from TDI-induced asthma can occur and only after long-term work cessation. Nonspecific bronchial hyperresponsiveness to methacholine can persist even in the absence of bronchial hyperresponsiveness to TDI, suggesting permanent chronic damage to mechanisms controlling airway tone.     

Virus-induced airway hyperresponsiveness in the guinea-pig: possible involvement of histamine and inflammatory cells

1. Guinea-pig tracheal contractions by histamine and by the cholinoceptor agonist, arecoline, are significantly enhanced (30% and 20%, respectively), 96 h after intra-tracheal inoculation with Parainfluenza-3 (PI-3) virus. 2. The airway hyperresponsiveness in animals inoculated with virus coincides with a significant increase in the number of broncho-alveolar cells (82%), and in the albumin concentration (121%) in lung lavage fluid, relative to values obtained in guinea-pigs challenged with control solution. 3. The chemiluminescence production by isolated broncho-alveolar cells, obtained from virus-infected guinea-pigs 96 h after inoculation stimulated with PI-3 virus in vitro, is significantly reduced by 42% relative to broncho-alveolar cells obtained from animals inoculated with control solution. This diminution was not specific for stimulation by PI-3 virus since the chemiluminescence production was also significantly reduced by 30% in response to zymosan. 4. Pretreatment of the guinea-pigs with the anti-allergic drugs, oxatomide (2.5 mg kg-1) or nedocromil (2.5 mg kg-1), or the specific H1-histamine receptor antagonist, levocabastine (0.25 mg kg-1), administered intra-peritoneally twice a day for five successive days, inhibits the virus-induced airway hyperresponsiveness, suppresses the influx of broncho-alveolar cells and increase in albumin content, and corrects the reduced chemiluminescence production by broncho-alveolar cells in response to zymosan. 5. In contrast, the cyclo-oxygenase inhibitor, suprofen (5.0 mg kg-1), the 5-HT2 receptor antagonist, ketanserin (0.63 mg kg-1), or the Ca2+ overload blocker, flunarizine (2.5 mg kg-1) do not modify the above mentioned processes. 6. The platelet-activating factor receptor antagonist, WEB 2170 (10 mg kg-1), reduces virus-induced airway hyperresponsiveness and influx of broncho-alveolar cells into the lungs but does not attenuate the increase of albumin in the bronchial lavage fluid. 7. Guinea-pigs nebulized with histamine, twice a day (30 min) during 4 successive days, do not demonstrate an increased airway responsiveness, but instead show tachyphylaxis in response to histamine in vitro. In addition, no influx of inflammatory cells is found in these animals. 8. These results suggest that histamine does not directly increase the responsiveness of the guinea-pig trachea; however, histamine may be involved in a cascade of events leading to airway hyperresponsiveness after a viral infection, a process that could be related to an influx and/or an activation of broncho-alveolar cells after PI-3 virus stimulation.     

Dissociation of airway responsiveness and bronchoalveolar lavage (BAL) cell composition in sensitized guinea-pigs after daily inhalation of ovalbumin

The association between inflammatory cell influx, cell activation status and change of airway responsiveness to acetylcholine (ACh) after daily inhalation of ovalbumin (OA) in sensitized guinea-pigs was investigated. Starting 3 weeks after sensitization (OA at 50 mg/kg s.c.+i.p.) guinea-pigs were exposed daily to 2% OA (10 min; under cover of 0.5 mg/kg mepyramine i.p. 15 min before OA) for 2 weeks. Concentration-response curves (CRCs) for inhaled ACh were performed 24 h after the last OA-challenge and 24 h after another single OA-inhalation 1 week later. CRCs for inhaled ACh were neither affected 24 h after the last OA challenge (daily for two weeks) nor 24 h after another OA-inhalation one week later. In contrast, bronchoalveolar lavage (BAL) from repeatedly OA- sensitized/-challenged guinea-pigs immediately after the last CRC showed a significant increase of total cell count by about tenfold and increases in eosinophils by about 20-fold, neutrophils by 30-fold, macrophages by about fivefold and lymphocytes by about tenfold (P < 0.05, multiple Wilcoxon-test). In contrast, markers of cell activation (EPO, MPO) were significantly decreased (P < 0.05). Methylprednisolone almost completely prevented these changes in increased cell numbers and decreased cell activation (vs OA contr., P < 0.05). The lack of increased airway hyperresponsiveness despite a massive inflammatory cell influx suggests other factors controlling airway responsiveness than inflammation.     

Effect of clenbuterol on sulfur dioxide-induced acute bronchitis in guinea pigs

When guinea pigs were exposed to sulfur dioxide (SO2) gas (800 ppm, 2 h), they showed hyperresponsiveness to intravenously administered serotonin (5-hydroxytryptamine (5-HT)). This hyperresponsiveness continued for over 24 h after the exposure to the gas. The degeneration, desquamation of epithelium, and edema of the lamina propria of the trachea and bronchi were observed in animals after a 2-h exposure of SO2 histopathologically. These changes seemed to be the early phase of acute bronchitis. Then, we examined the effect of clenbuterol, a selective beta-2 adrenoceptor agonist, on the SO2-induced bronchial hyperresponsiveness in these animals. Orally administered clenbuterol (1-10 micrograms/kg) suppressed the hyperresponsiveness to 5-HT in a dose-dependent manner. These results suggest that clenbuterol might inhibit the hyperresponsiveness that accompanies acute bronchitis and that this agent may be useful for remission of broncho-spasm.     

Involvement of tachykinin NK1 and NK2 receptors in substance P-induced microvascular leakage hypersensitivity and airway hyperresponsiveness in guinea-pigs

Tachykinins, such as substance P, might be involved in the development of airway hyperresponsiveness (AHR) and airway inflammation. However, it is unknown which tachykinin receptors mediate these biological activities. The effects of two antagonists of tachykinin neurokinin-1 (NK1) and tachykinin neurokinin-2 (NK2) receptors, SR 140333 and SR 48968, respectively, were investigated on substance P (SP)-induced airway hyperresponsiveness and potentiation of the histamine-induced increase in microvascular leakage, in phosphoramidon-pretreated guinea-pigs. Guinea-pigs were pretreated with phosphoramidon (0.1 mM aerosol for 15 min) and exposed 15 min later to saline solution alone or to saline solution containing SP (0.1 mg.mL-1 for 30 min). Twenty four hours later, the animals were anaesthetized and prepared for the recording of the pulmonary inflation pressure (PIP) to acetylcholine or for the investigation of microvascular leakage to histamine. Pretreatment of the guinea-pigs with a single dose of SR 48968 (1 mg.kg-1, i.p.) 30 min before SP exposure, significantly prevented the development of AHR, whereas SR 140333 (1 mg.kg-1, i.p.) did not. In a second set of experiments, phosphoramidon-pretreated guinea-pigs exposed to SP presented a significant potentiation of the histamine-induced increase in microvascular leakage in pulmonary airways. When the guinea-pigs were pretreated with SR 140333, an inhibition of the increased microvascular leakage to histamine was observed. In contrast, no significant inhibitory activity was noted when the guinea-pigs were pretreated with SR 48968. The present data demonstrate the importance of tachykinin NK2 receptor stimulation in the development of airway hyperresponsiveness and that of tachykinin NK1 receptor stimulation in microvascular leakage hypersensitivity in phosphoramidon-pretreated and substance P-exposed guinea-pigs. The results also suggest a dissociation between the presence of microvascular leakage and the occurrence of airway hyperresponsiveness.     

Blockade of airway inflammation and hyperresponsiveness by HIV-TAT-dominant negative Ras

We have reported previously that HIV-TAT-dominant negative (dn) Ras inhibits eosinophil adhesion to ICAM-1 after activation by IL-5 and eotaxin. In this study, we evaluated the role of Ras in Ag-induced airway inflammation and hyperresponsiveness by i.p. administration into mice of dnRas, which was fused to an HIV-TAT protein transduction domain (TAT-dnRas). Uptake of TAT-dnRas (t(1/2) = 12 h) was demonstrated in leukocytes after i.p. administration. OVA-sensitization significantly increased eosinophil and lymphocyte numbers in bronchoalveolar lavage fluid 24 h after final challenge. Treatment of animals with 3-10 mg/kg TAT-dnRas blocked the migration of eosinophils from 464 +/- 91 x 10(3)/ml to 288 +/- 79 x 10(3)/ml with 3 mg/kg of TAT-dnRas (p < 0.05), and further decreased to 116 +/- 63 x 10(3)/ml after 10 mg/kg TAT-dnRas (p < 0.01). Histological examination demonstrated that inflammatory cell infiltration (largely eosinophils and mononuclear cells) and mucin production around the airways caused by OVA were blocked by TAT-dnRas. OVA challenge also caused airway hyperresponsiveness to methacholine, which was dose dependently blocked by treatment with TAT-dnRas. TAT-dnRas also blocked Ag-induced IL-4 and IL-5, but not IFN-gamma, production in lung tissue. Intranasal administration of IL-5 caused eosinophil migration into the airway lumen, which was attenuated by pretreatment with TAT-dnRas. By contrast, TAT-green fluorescent protein or dnRas lacking the TAT protein transduction domain did not block airway inflammation, cytokine production, or airway hyperresponsiveness. We conclude that Ras mediates Th2 cytokine production, airway inflammation, and airway hyperresponsiveness in immune-sensitized mice.     

Distribution of CD4+ T-lymphocytes levels in patients with clinical symptoms of AIDS in three west African countries

The characteristics of airway responsiveness to acetylcholine (ACh) in congenitally bronchial-hypersensitive (BHS) and bronchial-hyposensitive (BHR) guinea pigs were clarified in vivo and in vitro. We measured the change in ventilatory mechanics in response to ACh inhalation by means of the bodyplethysmograph and the contractile responses of isolated trachea to ACh and carbachol (CCh). Further, muscarinic receptor subtypes involved these responses were identified. The basal values for ventilatory mechanics in BHS were not significantly different from those in BHR. Respiratory resistance to ACh was progressively increased in a time- and dose-dependent manner in BHS. The contractile responses of tracheal smooth muscle to ACh in BHS were significantly greater than those in BHR, but CCh-induced responses in BHS and BHR were similar. ACh- and CCh-induced contractions were mediated via M3 receptors. These results suggested that the falling-down of BHS in response to ACh inhalation was caused by the strong constriction of the airway and the reduction in ventilation. Moreover, the airway hyperresponsiveness to ACh in BHS might be partly dependent on the change in acetylcholinesterase activity.