rs-5186 and Asthma

The effects of CS-518, a thromboxane A2 synthase inhibitor, on antigen-induced dual bronchial responses, airway hyperresponsiveness (AHR) and airway eosinophilia were investigated in an experimental guinea pig model of the late asthmatic response. Oral CS-518 (1 and 10 mg/kg) inhibited immediate and late asthmatic responses dose-dependently. It also inhibited AHR and eosinophil accumulation after antigen challenge. Therefore, thromboxane A2 is possibly involved in development of the late asthmatic response and AHR, and CS-518 was inferred to inhibit these via inhibition of eosinophil accumulation and thromboxane production.

Topics: Animals; Asthma; Bronchial Hyperreactivity; Bronchial Provocation Tests; Bronchoalveolar Lavage Fluid; Chemotaxis, Leukocyte; Disease Models, Animal; Dose-Response Relationship, Drug; Enzyme Inhibitors; Eosinophils; Guinea Pigs; Male; Methacholine Chloride; Ovalbumin; Pulmonary Eosinophilia; Thiophenes; Thromboxane-A Synthase

The effects of CS-518 (sodium 2-(1-imidazolylmethyl)-4,5-dihydrobenzo[b]thiophene-6-carboxylate) , a thromboxane A2 synthase inhibitor, on eosinophil accumulation and activation were investigated in an experimental asthmatic guinea pig model and several cellular models. In the in vivo studies, CS-518 inhibited the biphasic eosinophil accumulation in the bronchoalveolar lavage fluid, potently in the early phase, but less potently in the delayed phase. On the other hand, even at the lower dose, CS-518 completely inhibited the hypodensity of eosinophils in the delayed phase. In the in vitro studies, CS-518 suppressed thromboxane A2 production and potentiated prostaglandin I2 production from guinea pig eosinophils. Moreover, CS-518 and prostaglandin I2 suppressed chemotaxis, peroxidase release and superoxide generation in guinea pig eosinophils. In addition, the present studies provide further support for the possibility that thromboxane A2 and prostaglandin I2, which are produced in bronchoalveolar tissue and within eosinophils, are involved in modulation of eosinophil function and suggest that CS-518 is a potent inhibitor of eosinophil activation.

Topics: Animals; Asthma; Bronchoalveolar Lavage Fluid; Chemotaxis, Leukocyte; Eosinophils; Epoprostenol; Guinea Pigs; In Vitro Techniques; Male; Peroxidases; Platelet Activating Factor; Pulmonary Alveoli; Superoxides; Thiophenes; Thromboxane A2; Thromboxane-A Synthase

The anti-asthmatic effects of CS-518 (sodium 2-(1-imidazolylmethyl)-4,5-dihydrobenzo[b]thiophene-6-carboxylate) , a specific thromboxane A2 (TXA2) synthase inhibitor, were investigated in the ovalbumin-sensitized guinea pig asthmatic model. Although CS-518 slightly inhibited (about 25%) whole bronchoconstriction, it significantly inhibited the antigen-induced bronchoconstriction mediated by slow-reacting substance of anaphylaxis (SRS-A), which was not reduced by chlorpheniramine, a histamine H1 antagonist. On the other hand, indomethacin, a cyclooxygenase inhibitor, potentiated the SRS-A-mediated constriction. CS-518 strongly, and indomethacin slightly, suppressed the leukotriene D4-induced bronchoconstriction. CS-518 clearly inhibited the antigen-induced airway hyperresponsiveness, but this compound had no effect on the airway hyperresponsiveness induced by U-46619, a TXA2-mimetic agent, and propranolol. These results suggest that CS-518 suppresses the development of bronchoconstriction and airway hyperresponsiveness in asthmatic models by inhibition of TXA2 synthesis with the concomitant increase in bronchodilating prostaglandins such as prostaglandin E2 and prostaglandin I2.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Asthma; Bronchial Hyperreactivity; Bronchoconstriction; Chlorpheniramine; Disease Models, Animal; Guinea Pigs; Indomethacin; Male; Methacrylates; Ovalbumin; Propranolol; Prostaglandin Endoperoxides, Synthetic; SRS-A; Thiophenes; Thromboxane A2; Thromboxane-A Synthase; Vasoconstrictor Agents