Effects of Prostaglandin D 2 , 15-Deoxy- 12,14 -prostaglandin J 2 , and Selective DP 1 and DP 2 Receptor Agonists on Pulmonary Infiltration of Eosinophils in Brown Norway Rats Wagdi Almishri, Chantal Cossette, Joshua Rokach, James G. Martin, Qutayba Hamid, and William S. Powell Meakins-Christie Laboratories, Department of Medicine, McGill University, Montreal, Quebec, Canada (W.A., C.C., J.G.M., Q.H., W.S.P.); and Claude Pepper Institute and Department of Chemistry, Florida Institute of Technology, Melbourne, Florida (J.R.) Received October 14, 2004; accepted December 6, 2004 ABSTRACT Prostaglandin (PG) D 2 is an arachidonic acid metabolite that is released by allergen-stimulated mast cells. It is a potent in vitro chemoattractant for human eosinophils, acting through the DP 2 receptor/chemoattractant receptor-homologous molecule ex- pressed on Th2 cells (CRTH2). Furthermore, there is in vivo evidence that PGD 2 contributes to allergen-induced pulmonary eosinophilia via its classic DP 1 receptor. The PGD 2 -derived product 15-deoxy- 12,14 -PGJ 2 is widely used as a peroxisome proliferator-activated receptor  agonist and has been shown to have anti-inflammatory properties. However, this substance can also activate eosinophils in vitro through the DP 2 receptor. The objectives of the present study were to determine whether PGD 2 and 15-deoxy- 12,14 -PGJ 2 can induce pulmonary eosin- ophilia, and, if so, to examine the abilities of selective DP 1 and DP 2 receptor agonists to induce this response. Brown Norway rats were treated by intratracheal instillation of PGs. Vehicle and 5-oxo-6,8,11,14-eicosatetraenoic acid were used as neg- ative and positive controls, respectively. Lung eosinophils were identified by immunostaining of lung sections with an antibody to major basic protein. Both PGD 2 and 15-deoxy- 12,14 -PGJ 2 induced robust eosinophilic responses that were apparent by 12 h and persisted for at least 48 h. Two selective DP 2 receptor agonists, 15R-methyl-PGD 2 and 13–14-dihydro-15- keto-PGD 2 , induced similar responses, the former being more potent than PGD 2 , whereas the latter was less potent. The selective DP 1 receptor agonist BW245C [(4S)-(3-[(3R,S)-3-cyclo- hexyl-3-hydroxypropyl]-2,5-dioxo)-4-imidazolidineheptanoic acid] was completely inactive. We conclude that PGD 2 and 15-deoxy-  12,14 -PGJ 2 induce eosinophil infiltration into the lungs through the DP 2 receptor. The potent in vitro DP 2 receptor agonist 15R- methyl-PGD 2 is also very active in vivo and should be a useful tool in examining the role of this receptor. Prostaglandin (PG) D 2 is a metabolite of arachidonic acid that is formed by the action of PGD synthase on the cycloox- ygenase product PGH 2 . There are two enzymes that catalyze this reaction: lipocalin-type PGD synthase, which is found in the central nervous system and hematopoietic PGD syn- thase, which is present in antigen-presenting cells, mast cells (Urade and Hayaishi, 2000), and Th2 cells (Tanaka et al., 2000). The association of PGD 2 with mast cells has focused attention on its possible role in asthma and other allergic diseases. High levels of this prostaglandin are rapidly re- leased into the airways after allergen challenge of asthmatic human subjects (Murray et al., 1986). The recent finding by Narumiya’s group that disruption of the classic G s -coupled (DP 1 ) receptor for PGD 2 protects mice against asthma-like responses after antigen challenge (Mat- suoka et al., 2000) has provoked considerable interest in the role of PGD 2 in this disease. Mice lacking this receptor ex- hibit reduced pulmonary eosinophilia, hyperresponsiveness, and Th2 cytokine levels in response to antigen compared with wild-type mice (Matsuoka et al., 2000). Similarly, a DP 1 receptor antagonist was reported to reduce pulmonary eosin- ophilia in a guinea pig model of asthma (Arimura et al., This study was supported by Canadian Institutes of Health Research Grants MOP-6254 (to W.S.P.), MOP-13273 (to Q.H.), and MOP-10381 (to J.G.M.); the J. T. Costello Memorial Research Fund; and National Institutes of Health Grants DK44730 and HL69835 (to J.R.). J.R. also acknowledges the National Science Foundation for an AMX-360 NMR instrument Grant CHE- 90-13145. Article, publication date, and citation information can be found at http://jpet.aspetjournals.org. doi:10.1124/jpet.104.079079. ABBREVIATIONS: PG, prostaglandin; Th2, T helper 2; CRTH2, chemoattractant receptor-homologous molecule expressed on Th2 cells; dhk-PGD 2 , 13,14-dihydro-15-ketoprostaglandin D 2 ; 15d-PGJ 2 , 15-deoxy- 12,14 -prostaglandin J 2 ; PPAR, peroxisome proliferator activated receptor ; 5-oxo-ETE, 5-oxo-6,8,11,14-eicosatetraenoic acid; BW245C, (4S)-(3-[(3R,S)-3-cyclohexyl-3-hydroxypropyl]-2,5-dioxo)-4-imidazo- lidineheptanoic acid; MBP, major basic protein; MDC, macrophage-derived chemokine (CCL22). 0022-3565/05/3131-64 –69$20.00 THE JOURNAL OF PHARMACOLOGY AND EXPERIMENTAL THERAPEUTICS Vol. 313, No. 1 Copyright © 2005 by The American Society for Pharmacology and Experimental Therapeutics 79079/1195211 JPET 313:64–69, 2005 Printed in U.S.A. 64 at ASPET Journals on July 20, 2018 jpet.aspetjournals.org Downloaded from