[Experimental study on the role of prostaglandin D2 in the pathogenesis of bronchial asthma]

Various kinds of chemical mediators have been implicated in the pathogenesis of bronchial asthma. PGD2 is a cyclooxygenase product which has various physiological effects. In this experimental study, we investigated the role of PGD2 in the pathogenesis of bronchial asthma. In a bioassay system, PGD2 caused dose-dependent contractile responses in non-sensitized guinea pig trachea and lung tissue strips. The subthreshold concentration of PGD2 in both strips was 25 ng/ml. Acetylcholine-induced contractile responses in both strips were significantly increased by continuous infusion of PGD2. In the experimental model of bronchial asthma, the levels of PGD2 were significantly increased in serum, bronchoalveolar lavage fluid (BALF) and lung tissue of sensitized guinea pigs after antigen challenge. We have also reported that the levels of PGD2 in BALF were elevated in patients with stable state bronchial asthma. These results suggest that PGD2 may be a key substance that increases airway responsiveness and induces asthmatic attacks.