endothelin-1 and Bronchial-Hyperreactivity

Bronchial hyperresponsiveness (BHR) is a fundamental characteristic of asthma and has become part of a more recent definition of asthma. Data show a close link between bronchial hyperresponsiveness (both transient and persistent) and airway inflammation. Airway inflammation is orchestrated by a complex network of cytokines. It has been considered that endothelin-1 is involved in bronchoconstriction and airway structural remodelling and has several pro-inflammatory properties of potential relevance to asthma. We focus on endothelin-1, its activities and interaction with other cytokines in the pathogenesis of asthma.

Topics: Airway Resistance; Animals; Asthma; Bronchial Hyperreactivity; Cytokines; Endothelin-1; Granulocyte-Macrophage Colony-Stimulating Factor; Humans; Tumor Necrosis Factor-alpha

Endothelin (ET)-1 is a potent bronchoconstrictor, and asthmatics demonstrate bronchial hyperresponsiveness to ET-1 given by inhalation. Angiotensin II (Ang II) is increased in plasma in acute severe asthma, causes bronchoconstriction in asthmatics, and potentiates contractions induced by ET-1 in bovine bronchial smooth muscle in vitro, and contractions induced by methacholine both in vitro and in vivo. We wished to examine any potentiation of the bronchoconstrictor activity of inhaled ET-1 by infused Ang II at subbronchoconstrictor doses.. Double-blind randomized placebo-controlled study.. Asthma research unit in university hospital.. Eight asthmatic subjects with baseline FEV1 88% predicted, bronchial hyperreactivity (geometric mean, concentration of methacholine producing 20% fall, methacholine PC20 2.5 mg/mL), and mean age 37.1 years.. We examined the effect of subbronchoconstrictor doses of infused Ang II (1 ng/kg/min and 2 ng/kg/min) or placebo on bronchoconstrictor responses to inhaled ET-1 (dose range, 0.96 to 15.36 nmol).. Oxygen saturation, noninvasive BP, and spirometric measurements were made throughout the study visits. Blood was sampled for plasma Ang II levels at baseline and before and after ET-1 inhalation.. Ang II infusion did not produce bronchoconstriction per se at either dose prior to ET-1 challenge. Bronchial challenge with inhaled ET-1 produced dose-dependent bronchoconstriction, but there was no difference in bronchial responsiveness to ET-1 comparing infusion of placebo with Ang II at 1 ng/kg/min or 2 ng/kg/min (geometric mean, concentration of ET-1 producing 15% fall, 5.34 nmol, 4.95 nmol, and 4.96 nmol, respectively) (analysis of variance, p > 0.05). There was an increase in systolic and diastolic BP at the higher dose of Ang II compared to placebo (mean 136/86 vs 117/75 mm Hg, respectively). Plasma Ang II was elevated following infusion of both doses of Ang II compared to placebo.. In contrast to the potentiating effect on methacholine-induced bronchoconstriction, Ang II at subbronchoconstrictor doses does not potentiate ET-1-induced bronchoconstriction in asthma.

Topics: Adult; Angiotensin II; Asthma; Blood Pressure; Bronchial Hyperreactivity; Bronchoconstriction; Double-Blind Method; Drug Synergism; Endothelin-1; Female; Humans; Male; Middle Aged

It has recently been exhibited that Rac1 expression is increased in the bronchial tissue of a murine model with repeated antigen-challenged airway hyperresponsiveness (AHR). In the present study, the role of Rac1 in endothelin-1 (ET-1)-induced bronchial contraction and myosin light chain (MLC) phosphorylation was examined in AHR mice. Enhanced reactions in AHR mice were prevented by the Rac1 inhibitor NSC23766. These findings suggest that increased activation of Rac1 might be responsible for the enhancement of the bronchial contraction induced by ET-1 in AHR.

Topics: Aminoquinolines; Animals; Bronchi; Bronchial Hyperreactivity; Bronchoconstriction; Disease Models, Animal; Endothelin-1; Male; Mice; Mice, Inbred BALB C; Muscle, Smooth; Myosin Light Chains; Phosphorylation; Pyrimidines; rac1 GTP-Binding Protein

Epidemiological studies have revealed that intrauterine growth retardation (IUGR) or low birth weight is linked to the later development of asthma. Epigenetic regulatory mechanisms play an important role in the fetal origins of adult disease. However, little is known regarding the correlation between epigenetic regulation and the development of asthma following IUGR.. An IUGR and ovalbumin (OVA)-sensitization/challenge rat model was used to study whether epigenetic mechanisms play a role in the development of asthma following IUGR.. Maternal nutrient restriction increased histone acetylation levels of the endothelin-1 (ET-1) gene promoter in lung tissue of offspring, but did not cause significant alterations of DNA methylation. The effect was maintained until 10 weeks after birth. Furthermore, these epigenetic changes may have induced IUGR individuals to be highly sensitive to OVA challenge later in life, resulting in more significant changes related to asthma.. These findings suggest that epigenetic mechanisms might be closely associated with the development of asthma following IUGR, providing further insight for improved prevention of asthma induced by environmental factors.

Topics: Acetylation; Age Factors; Allergens; Animals; Asthma; Bronchial Hyperreactivity; Disease Models, Animal; DNA Methylation; Endothelin-1; Epigenesis, Genetic; Female; Fetal Growth Retardation; Gene Expression Regulation; Genetic Predisposition to Disease; Histones; Maternal Nutritional Physiological Phenomena; Nutritional Status; Ovalbumin; Pregnancy; Promoter Regions, Genetic; Rats, Sprague-Dawley; Risk Factors

The current paradigm describing asthma pathogenesis recognizes the central role of abnormal epithelial function in the generation and maintenance of the disease. However, the mechanisms responsible for the initiation of airway remodeling, which contributes to decreased lung function, remain elusive. Therefore, we aimed to determine the role of altered pulmonary gene expression in disease inception and identify proremodeling mediators.. Using an adenoviral vector, we generated mice overexpressing smad2, a TGF-β and activin A signaling molecule, in the lung. Animals were exposed to intranasal ovalbumin (OVA) without systemic sensitization.. Control mice exposed to inhaled OVA showed no evidence of pulmonary inflammation, indices of remodeling, or airway hyper-reactivity. In contrast, local smad2 overexpression provoked airway hyper-reactivity in OVA-treated mice, concomitant with increased airway smooth muscle mass and peribronchial collagen deposition. Pulmonary eosinophilic inflammation was not evident, and there was no change in serum IgE or IgG1 levels. The profound remodeling changes were not mediated by classical pro-inflammatory Th2 cytokines. However, uric acid and interleukin-1β levels in the lung were increased. Epithelial-derived endothelin-1 and fibroblast growth factor were also augmented in smad2-expressing mice. Blocking endothelin-1 prevented these phenotypic changes.. Innate epithelial-derived mediators are sufficient to drive airway hyper-reactivity and remodeling in response to environmental insults in the absence of overt Th2-type inflammation in a model of noneosinophilic, noninflammed types of asthma. Targeting potential asthma therapies to epithelial cell function and modulation of locally released mediators may represent an effective avenue for therapeutic design.

Topics: Airway Remodeling; Animals; Asthma; Bronchial Hyperreactivity; Disease Models, Animal; Endothelin-1; Female; Gene Expression; Inflammation Mediators; Mice; Mice, Transgenic; Muscle, Smooth; Ovalbumin; Respiratory Mucosa; Smad2 Protein

The effects of sphingosine-1-phosphate (S1P) on bronchial smooth muscle (BSM) contractility were investigated in naive mice. S1P had no effect on the basal tone of the isolated BSM tissues. However, in the presence of S1P (10(-6) M), the BSM contractions induced by acetylcholine (ACh) and endothelin-1 (ET-1) were significantly augmented: both the ACh and ET-1 concentration-response curves were significantly shifted to the left. In contrast, the pretreatment with S1P had no effect on the contractions induced by high K(+) depolarization. It is thus possible that S1P augments BSM contraction induced by the activation of G protein-coupled receptors.

Topics: Acetylcholine; Animals; Bronchi; Bronchial Hyperreactivity; Endothelin-1; Lysophospholipids; Male; Mice; Mice, Inbred BALB C; Muscle Contraction; Muscle, Smooth; Potassium; Receptors, G-Protein-Coupled; Sphingosine; Vasodilator Agents

Regular use of beta(2)-adrenoceptor agonists may enhance non-specific airway responsiveness and inflammation. In earlier experimental studies, we showed that prolonged in vitro fenoterol exposure induced airway sensitization via perturbed epithelial regulation of bronchoconstriction. The aim of the present work was to examine the involvement of inflammatory mediator genes and proinflammatory cells and to investigate the role of the bronchial epithelium in these untoward effects. Bronchial tissues were surgically removed from 17 ex-smokers. Bronchial rings and primary cultures of bronchial epithelial cells were incubated with 0.1microM fenoterol for 15h. Levels of mRNA-expression were analyzed using a real-time quantitative reverse transcription-polymerase chain reaction array. Bronchial rings were contracted with endothelin-1 and immune cell infiltration was assessed by immunohistochemistry. Compared to paired controls, fenoterol up-regulated the mRNAs of cytokines/proteins implicated in the recruitment of T and B cells or the activation and proliferation of bronchial epithelial cells (CCL20/MIP-3alpha, FOXA2, PPAR-gamma) in isolated bronchi and in cultured epithelial cells. Fenoterol exposure significantly enhanced CD8(+)-T and differentiated CD138(+)-B-cells infiltration into the bronchi, especially the subepithelial area. Increase in CD8 or CD138 labeling-intensity strongly correlated with rise in maximal contraction to endothelin-1 induced by fenoterol exposure. In summary, our results show that fenoterol modulates the T and B cells chemotaxis possibly via the epithelial chemokine secretion in isolated bronchi from ex-smokers. They also suggest that the infiltration of resident T and B cells into the subepithelial area is associated with an increase in airway responsiveness due to fenoterol exposure.

Topics: Adrenergic beta-Agonists; Aged; B-Lymphocytes; Bronchi; Bronchial Hyperreactivity; Bronchoconstriction; Bronchoconstrictor Agents; CD8-Positive T-Lymphocytes; Cells, Cultured; Chemotaxis, Leukocyte; Cytokines; Dose-Response Relationship, Drug; Endothelin-1; Epithelial Cells; Female; Fenoterol; Gene Expression Regulation; Humans; Immunohistochemistry; Inflammation Mediators; Lung Neoplasms; Male; Middle Aged; Pulmonary Disease, Chronic Obstructive; Receptors, Adrenergic, beta; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Smoking Cessation; Time Factors

Endothelins are proinflammatory, profibrotic, broncho- and vasoconstrictive peptides, which play an important role in the development of airway inflammation and remodeling in asthma. The study was undertaken to evaluate the endothelin-1 (ET-1) levels in exhaled breath condensate (EBC) of asthmatics with different degree in asthma severity. EBC was collected from 31 patients with allergic asthma (11 with steroid-naïve mild asthma, 10 with ICS-treated, stable mild-to-moderate asthma, 10 with ICS-treated unstable, severe asthma) and 7 healthy volunteers. In the three groups of asthmatics, ET-1 concentrations in EBC were significantly higher than in healthy volunteers. ET-1 levels were significantly higher in patients with unstable asthma than in the two groups with stable disease. There was a significant correlation between ET-1 levels and FENO in the three groups of asthmatics and between ET-1 and blood eosinophil counts in the group of patients with unstable asthma. Measurements of ET-1 in EBC may provide another useful diagnostic tool for detecting and monitoring inflammation in patients with asthma.

Topics: Adult; Asthma; Breath Tests; Bronchial Hyperreactivity; Case-Control Studies; Endothelin-1; Female; Humans; Inflammation Mediators; Male; Middle Aged; Nitric Oxide

The role of endothelin, PAF and thromboxane A2 in airway hyperreactivity (AHR) to carbachol induced by ovalbumin sensitization and challenge in Balb/c mice was investigated. Ovalbumin sensitization and challenge induced significant AHR to carbachol in actively sensitized and challenged mice. Treatment of these mice with the PAF antagonist CV-3988 (10 microg kg(-1), i.v.) completely abolished OVA-induced AHR to carbachol. Treatment of sensitized mice with the TxA2 antagonist L-654,664 (1 mg kg(-1), i.v.) partially blocked the induction of AHR in OVA-challenged mice. The intranasal administration of 50 pmol of the ET(A) receptor antagonist BQ-123 had no effect on the PIP but produced a significant reduction at the dose of 100 pmol. The intravenous administration of BQ-123 (100 pmol) reduced the PIP only at the highest doses of carbachol. The ET(B) receptor antagonist BQ-788 administered either via the intranasal or intravenous route had no effect on the PIP at the dose of 100 pmol. Naïve mice treated with either U-44069 (25 or 100 microg kg(-1), i.v.), endothelin-1 (100 pmol, intranasally) or the ET(B) receptor agonist IRL-1620 (100 pmol, intranasally) showed a marked increase in airway reactivity to carbachol. These results suggest an important role for endothelin, PAF and thromboxane A2 in AHR in mice actively sensitized and challenged with ovalbumin.

Topics: Animals; Antihypertensive Agents; Bronchial Hyperreactivity; Carbachol; Endothelin B Receptor Antagonists; Endothelin-1; Endothelins; Male; Mice; Mice, Inbred BALB C; Oligopeptides; Ovalbumin; Peptide Fragments; Phospholipid Ethers; Piperidines; Platelet Activating Factor; Platelet Aggregation Inhibitors; Prostaglandin Endoperoxides, Synthetic; Receptor, Endothelin B; Thromboxane A2

Exercise-induced bronchoconstriction (EIB) is a highly prevalent condition, whose pathophysiology is not well understood. Endothelins are proinflammatory, profibrotic, broncho- and vasoconstrictive peptides which play an important role in the development of airway inflammation and remodeling in asthma. The aim of the study was to evaluate the changes in endothelin-1 levels in exhaled breath condensate following intensive exercise in asthmatic patients.. The study was conducted in a group of 19 asthmatic patients (11 with EIB, 8 without EIB) and 7 healthy volunteers. Changes induced by intensive exercise in the concentrations of endothelin-1 (ET-1) in exhaled breath condensate (EBC) during 24 hours after an exercise challenge test were determined. Moreover, the possible correlations of these measurements with the results of other tests commonly associated with asthma and with the changes of airway inflammation after exercise were observed.. In asthmatic patients with EIB a statistically significant increase in the concentration of ET-1 in EBC collected between 10 minutes and 6 hours after an exercise test was observed. The concentration of ET-1 had returned to its initial level 24 hours after exercise. No effects of the exercise test on changes in the concentrations of ET-1 in EBC in either asthmatic patients without EIB or healthy volunteers were observed. A statistically significant correlation between the maximum increase in ET-1 concentrations in EBC after exercise and either baseline FENO and the increase in FENO or BHR to histamine 24 hours after exercise in the groups of asthmatics with EIB was revealed.. The release of ET-1 from bronchial epithelium through the influence of many inflammatory cells essential in asthma and interactions with other cytokines, may play an important role in increase of airway inflammation which was observed after postexercise bronchoconstriction in asthmatic patients.

Topics: Adult; Analysis of Variance; Asthma, Exercise-Induced; Breath Tests; Bronchial Hyperreactivity; Bronchial Provocation Tests; Bronchoconstriction; Case-Control Studies; Disease Progression; Endothelin-1; Exhalation; Female; Humans; Inflammation Mediators; Male; Nitric Oxide; Probability; Reference Values; Sensitivity and Specificity; Spirometry

The purpose of this study was to evaluate the role of endothelin-1 (ET-1) and its receptors in the airway hyperreactivity of horses with obstructive pulmonary disease associated with summer pasture (SPAOPD). The right diaphragmatic lobe of the lung of 8 clinically healthy (unaffected) and 8 SPAOPD-affected horses was collected immediately after euthanasia. Bronchial rings (4 mm wide) were prepared and mounted in organ baths and attached to force transducers interfaced with a polygraph. Four rings were used to study each ET-1 receptor; 1 ring served as the control, and the other 3 were incubated with 10(-9), 10(-7), or 10(-5) M of either BQ-123, an ET(A)-receptor antagonist, or IRL-1038, an ET(B)-receptor antagonist. Cumulative concentrations (10(-8.5) to 10(-6) M) of ET-1 were applied to all rings. Using pooled pulmonary tissue from different regions of the lung, we performed a reverse-transcription polymerase chain reaction (RT-PCR) to determine ET(B)-receptor gene expression. Although ET-1 caused concentration-dependent bronchial ring contraction in both groups of horses, the rings of SPAOPD-affected horses had significantly greater contraction than the rings of unaffected horses. Whereas ET(A)-receptor blockade significantly increased the response to ET-1 in unaffected horses, ET(B)-receptor blockade significantly decreased the response in affected horses. The pA2 values showed a nonsignificant decrease in ET(A)-receptor affinity and a significant increase in ET(B)-receptor affinity in affected horses compared with unaffected horses. The ET(B)-receptor mRNA expression of the pooled pulmonary tissue showed a nonsignificant increase in affected horses compared with unaffected horses. The airway hyperreactivity to ET-1 observed in the bronchial rings from the affected horses appears to be due in part to activation of pulmonary ET(B) receptors, which appear to be inactive in unaffected horses.

Topics: Animals; Bronchial Hyperreactivity; Dose-Response Relationship, Drug; Endothelin-1; Gene Expression; Horse Diseases; Horses; Lung Diseases, Obstructive; Organ Culture Techniques; Poaceae; Receptors, Endothelin; Reverse Transcriptase Polymerase Chain Reaction; Seasons

Chronic exposure of human isolated bronchi to beta2-adrenergic agonists, especially fenoterol, potentiates smooth muscle contraction in response to endothelin-1 (ET-1), a peptide implicated in chronic inflammatory airway diseases. 5'-Cyclic adenosine monophosphate (cAMP) pathways are involved in fenoterol-induced hyperresponsiveness. The present study investigated whether chronic elevation of intracellular cAMP by other pathways than beta2-adrenoceptor stimulation provokes bronchial hyperresponsiveness. Samples from eighteen human bronchi were sensitized to ET-1 by prolonged incubation with 0.1 microM fenoterol (15 h, 21 degrees C), or, under similar conditions, were incubated with a selective type-3 phosphodiesterase inhibitor (1 microM siguazodan), two selective type-4 phosphodiesterase inhibitors (0.1 microM rolipram and 0.1 microM cilomilast), a combination of fenoterol and rolipram (0.1 microM each) or of fenoterol and cilomilast (0.1 microM each). Rolipram and cilomilast, but not siguazodan, induced hyperresponsiveness (p < 0.01 and p < 0.05 vs. paired controls, respectively) similar to the fenoterol effect. Fenoterol-induced bronchial hyperresponsiveness was significantly enhanced by coincubation with cilomilast (p < 0.05 vs. fenoterol alone) but not with rolipram. Our results suggest that prolonged activation of intracellular cAMP through phosphodiesterase 4 inhibition induces hyperresponsiveness to ET-1 in human isolated bronchi. However, differences in subcellular localization of phosphodiesterase 4 may provoke divergent responsiveness patterns when human bronchi are continuously exposed to selective phosphodiesterase inhibitors with or without beta2-adrenergic agonists.

Topics: 3',5'-Cyclic-AMP Phosphodiesterases; Adrenergic beta-2 Receptor Agonists; Adrenergic beta-Agonists; Bronchi; Bronchial Hyperreactivity; Carboxylic Acids; Cyclic AMP; Cyclic Nucleotide Phosphodiesterases, Type 3; Cyclic Nucleotide Phosphodiesterases, Type 4; Cyclohexanecarboxylic Acids; Endothelin-1; Fenoterol; Humans; In Vitro Techniques; Muscle Contraction; Muscle, Smooth; Nitriles; Phosphodiesterase Inhibitors; Rolipram

Airway hyperresponsiveness (AHR) associated with heightened airway resistance and inflammation is a characteristic feature of bronchial asthma. It has been demonstrated that contraclile responsiveness to endothelin-1 (ET-1) in repeated antigen challenge-induced airway hyperresponsive bronchial preparation was significantly increased. ET-1 is a potent contracting substance for various smooth muscles including airways. In addition to the classical Ca(2+)-mediated contraction, ET-1 also induced Ca(2+) sensitization of contraction. However, it is not clear whether ET-1 stimulation also activates the CPI-17 (PKC-potentiated inhibitory protein for heterotrimeric myosin light chain phosphatase of 17 kDa) pathway in airway smooth muscles. Therefore, the changes in ET-1-induced activation/phosphorylation of CPI-17 and myosin light chain (MLC) in bronchial smooth muscle of repeatedly antigen-challenged rats were examined. The levels of ET-1-induced phosphorylation of CPI-17 and MLC were increased much more markedly in the AHR group than in the sensitized control animals. It might be suggested that the augmented activation of CPI-17 observed in the hyperresponsive bronchial smooth muscle is responsible for the enhanced agonists-induced contraction of bronchial smooth muscle in AHR rats.

Topics: Animals; Bronchi; Bronchial Hyperreactivity; Calcium; Endothelin-1; Male; Muscle Proteins; Muscle, Smooth; Myosin Light Chains; Phosphoproteins; Phosphorylation; Rats

Changes in endothelin-1 (ET-1)-induced contraction and activation of RhoA in bronchial smooth muscle of repeatedly antigen-challenged rats, which exhibit marked airway hyperresponsiveness (AHR), were examined. The ET-1-induced contraction of bronchial smooth muscle was significantly enhanced in the repeatedly antigen-challenged group. In normal control animals, ET-1 induced time- and concentration-dependent translocation of RhoA to the plasma membrane, indicating activation of RhoA by ET-1 in rat bronchial smooth muscle. The level of ET-1-induced RhoA translocation was increased much more markedly in the AHR group than in the control animals. It is suggested that the augmented activation of RhoA observed in the hyperresponsive bronchial smooth muscle might be responsible for the enhanced ET-1-induced contraction of bronchial smooth muscle in AHR rats.

Topics: Amides; Animals; Antigens; Bronchi; Bronchial Hyperreactivity; Calcium; Dose-Response Relationship, Drug; Endothelin-1; Male; Muscle Contraction; Muscle, Smooth; Pyridines; Rats; Rats, Wistar; rhoA GTP-Binding Protein; Time Factors

To evaluate the inhibiting effect of niflumic acid (NFA), an inhibitor of calcium-activated chloride channel (ClCa) on airway epithelium, on the airway hyperresponsiveness in asthmatic mice.. BALB/c mice were randomly divided into an asthma group (A group), a NFA prevention asthmatic group (B group) and a sham-challenged group (C group). The airway pressure time index (APTI) and the content of ET-1 and NO in bronchoalveolar lavage fluid (BALF) in all groups were measured. With the isolated tracheal rings with integral epithelium or epithelium removed from the asthma group (A(1) group and A(2) group) and the sham-challenged group (C(1) group and C(2) group), the contractile responsiveness of various rings to methacholine (mACh) was examined, and its change was observed when the rings were exposed to NFA beforehand.. Compared with A group (1.62 +/- 0.14), the APTI in B group (1.21 +/- 0.07) was reduced remarkably (P < 0.01), and the contents of ET-1 [(103 +/- 9) ng/L] and NO [(48.5 +/- 3.2) micromol/L] in BALF of A group were significantly higher than those in B group, [(53 +/- 5) ng/L, (23.7 +/- 2.5) micromol/L (P < 0.01), respectively]. The ratios of maximum contractility in A(1), A(2), C(1) and C(2) groups were (3.79 +/- 0.44), (2.15 +/- 0.21), (1.26 +/- 0.14) and (2.06 +/- 0.18), respectively. The contractility of A(1) group was highest among all groups (all P < 0.01), but could be effectively decreased by NFA.. By inhibiting the special ClCa on the airway epithelium, NFA can inhibit the production of ET-1 and NO by epithelium and thus exert preventive effect on airway hyperresponsiveness in asthma.

Topics: Animals; Asthma; Bronchial Hyperreactivity; Bronchoalveolar Lavage Fluid; Endothelin-1; In Vitro Techniques; Male; Mice; Niflumic Acid; Nitric Oxide; Trachea

To determine a change in airway smooth muscle contractility in a murine model of allergic asthma, the responsiveness of airway smooth muscles isolated from ovalbumin (OA)-sensitized and -challenged mice was compared with that from control animals.. Actively sensitized mice were repeatedly challenged by ovalbumin (OA) antigen inhalation. Twenty-four h after the last antigen challenge, tracheal and bronchial smooth muscle responsiveness to acetylcholine (ACh) and endothelin-1 (ET-1) were measured. Airway microvascular leakage and histochemistry were also determined as indices of airway inflammation.. Both the ACh and ET-1 responsiveness of bronchial, but not tracheal, smooth muscles were significantly augmented in OA-challenged mice, whereas no significant change in the expression levels of M2, M3 and ETB receptors was observed. The Evans blue dye extravasation in the main bronchial, but not tracheal, tissue of OA-challenged mice was significantly increased as compared with that of sensitized control animals. A marked inflammatory cells infiltration was also observed in bronchial but not tracheal tissues of OA-challenged mice.. Repeated antigen challenge to sensitized mice caused a hyperresponsiveness of bronchial, but not tracheal, smooth muscle accompanied with bronchial tissue inflammation.

Topics: Acetylcholine; Animals; Antigens; Asthma; Bronchi; Bronchial Hyperreactivity; Capillary Permeability; Disease Models, Animal; Endothelin-1; Immunization; Male; Mice; Mice, Inbred BALB C; Muscle Contraction; Muscle, Smooth; Ovalbumin; Receptor, Endothelin B; Receptor, Muscarinic M1; Receptor, Muscarinic M2; Trachea

Within the airways, endothelin-1 (ET-1) can exert a range of prominent effects, including airway smooth muscle contraction, bronchial obstruction, airway wall edema, and airway remodeling. ET-1 also possesses proinflammatory properties and contributes to the late-phase response in allergic airways. However, there is no direct evidence for the contribution of endogenous ET-1 to airway hyperresponsiveness in allergic airways. Allergic inflammation induced in mice by sensitization and challenge with the house dust mite allergen Der P1 was associated with elevated levels of ET-1 within the lung, increased numbers of eosinophils within bronchoalveolar lavage fluid and tissue sections, and development of airway hyperresponsiveness to methacholine (P < 0.05, n = 6 mice per group). Treatment of allergic mice with an endothelin receptor antagonist, SB-217242 (30 mg x kg(-1) x day(-1)), during allergen challenge markedly inhibited airway eosinophilia (bronchoalveolar lavage fluid and tissue) and development of airway hyperresponsiveness. These findings provide direct evidence for a mediator role for ET-1 in development of airway hyperresponsiveness and airway eosinophilia in Der P1-sensitized mice after antigen challenge.

Topics: Animals; Bronchial Hyperreactivity; Bronchoalveolar Lavage Fluid; Carboxylic Acids; Cell Count; Endothelin Receptor Antagonists; Endothelin-1; Hypersensitivity; Indans; Leukocyte Count; Leukocytes; Macrophages, Alveolar; Male; Mice; Mice, Inbred CBA

Peroxynitrite plays an important role in the pathogenesis of airway inflammation. We have already found that peroxynitrite may contribute to decreased beta(2)-adrenoceptor responses in airway smooth muscle. However, it is not known whether peroxynitrite can alter neutral endopeptidase (EC 3.4.24.11; NEP) activity in the airways. This study was designed to determine whether peroxynitrite induces airway hyperresponsiveness to substance P (SP) and endothelin-1 (ET-1) through the inactivation of airway NEP.. We examined whether the administration of S-morpholinosydnonimine (SIN-1), a compound that releases peroxynitrite, increased bronchoconstrictor responses to SP and ET-1 in anesthetized guinea pigs. In addition, we assayed NEP activity in the airways of SIN-1-exposed guinea pigs.. Though SIN-1 (10(-7) M) alone had no effect on pulmonary resistance, pretreatment with SIN-1 significantly enhanced SP- and ET-1-induced bronchoconstriction. Pretreatment with phosphoramidon, an NEP inhibitor, also enhanced SP- and ET-1-induced bronchoconstriction. However, simultaneous administration of phosphoramidon and SIN-1 had no additive effect on SP- and ET-1-induced bronchoconstriction. Peroxynitrite formation by SIN-1 was completely inhibited by N-acetylcysteine (NAC) and glutathione (GSH) in vitro, and pretreatment with NAC and GSH significantly reversed the potentiation by SIN-1 of SP-induced bronchoconstriction. In addition, the NEP activity of the trachea after SIN-1 exposure was significantly reduced compared to the level in control guinea pigs (solvent for SIN-1: 30.0+/-4.2 fmol.min(-1).mg tissue(-1); 10(-7) M SIN-1; 15.5+/-4.5 fmol.min(-1).mg tissue(-1), p<0.05).. These findings suggest that peroxynitrite induces airway hyperresponsiveness to SP and ET-1 through the inactivation of airway NEP, and that peroxynitrite is an important mediator of the alterations in airway functions.

Topics: Animals; Bronchial Hyperreactivity; Bronchoconstriction; Endothelin-1; Enzyme Activation; Glycopeptides; Guinea Pigs; Male; Molsidomine; Neprilysin; Nitrates; Oxidants; Protease Inhibitors; Respiratory System; Substance P; Trachea; Vasodilator Agents

Endothelins (ETs) are a family of peptide mediators that have a number of biological properties, including the ability to act as potent bronchoconstrictors of isolated human airways. Moreover, elevated concentrations of ET-1 in the bronchoalveolar lavage fluid from patients with symptomatic asthma have also been detected. We investigated the possible contribution of ET-1 in the development of bronchial hyperresponsiveness and the role of inflammatory cell accumulation in rabbit lungs. Our data show that ET-1 challenge to rabbits does not modify basal lung function but results in an increased airway responsiveness to inhaled histamine. Endothelin-treated rabbits were 3-fold (P<0.01) more responsive to inhaled histamine when compared with vehicle-treated rabbits. This hyperresponsiveness was not associated with an alteration in either total or differential inflammatory cell numbers as assessed by bronchoalveolar lavage (BAL). Pre-treatment with capsaicin (80 mg/kg s.c.) did not alter basal lung function or basal responsiveness to inhaled histamine. While capsaicin had no significant effect on the acute bronchoconstriction induced by endothelin-1, this dose was sufficient to significantly inhibit the increase in airway responsiveness to inhaled histamine, achieved 24 h following endothelin-1 challenge. These results indicate that ET-1 may play a role in the development of bronchial hyperresponsiveness to inhaled histamine and that the maintenance of this state is unrelated to a detectable alteration in cellular infiltration within the airway lumen, but probably via the involvement of capsaicin-sensitive nerves.

Topics: Airway Resistance; Animals; Bronchial Hyperreactivity; Bronchoalveolar Lavage; Bronchoalveolar Lavage Fluid; Capsaicin; Dose-Response Relationship, Drug; Endothelin-1; Eosinophils; Female; Histamine; Leukocyte Count; Leukocytes, Mononuclear; Lung; Male; Neutrophils; Rabbits

We have previously shown that angiotensin II (AII) potentiates responses evoked by endothelin-1 (Et-1). In the present study, the additional ability of hypoxia or phorbol 12, 13-dibutyrate (PDBu) to evoke hyperreactivity was examined. In addition, the role of cyclooxygenase and 5-lipoxygenase metabolites of arachidonic acid in the potentiation evoked by AII, hypoxia or PDBu was studied, using indomethacin and nordihydroguaiaretic acid (NDGA). The involvement of protein kinase C in the enhanced response was examined using staurosporine. Contractions were measured isometrically from rings of bovine bronchi. Contractions evoked by Et-1 alone were unaltered by indomethacin (10(-6)M), NDGA (10(-5)M) or staurosporine (3 x 10(-8)M). AII (3 x 10(-7)M), hypoxia (4% O2) or PDBu (10(-8)M) each significantly potentiated the contractions evoked by Et-1. Indomethacin (10(-6)M) virtually abolished the effect of AII, hypoxia or PDBu. NDGA (10(-5)M) reversed the potentiating effect of both AII and hypoxia and partially reversed PDBu-evoked enhancement of Et-1-mediated responses. Staurosporine (3 x 10(-8)M) abolished the ability of AII or PDBu, but not hypoxia, to enhance Et-1-mediated contractions. In conclusion, AII, hypoxia and PDBu evoke hyperresponsiveness which is mediated by prostanoids and/or leukotrienes, the precise nature of which remains to be elucidated. Differences in the ability of staurosporine to reverse AII- and hypoxia-induced hyperreactivity suggests, however, that these conditions may generate different eicosanoids.

Topics: Animals; Arachidonate 5-Lipoxygenase; Arachidonic Acid; Bronchial Hyperreactivity; Cattle; Cyclooxygenase Inhibitors; Drug Synergism; Endothelin-1; Enzyme Inhibitors; Indomethacin; Lipoxygenase Inhibitors; Masoprocol; Muscle Contraction; Prostaglandin-Endoperoxide Synthases; Protein Kinase C; Staurosporine