Prostaglandin D2-induced eosinophilic airway inflammation is mediated by CRTH2 receptor.
Mast cell-derived prostaglandin D(2) (PGD(2)) is one of the essential modulators of eosinophilic airway inflammation in asthma and allergic rhinitis. Two G protein-coupled receptors for PGD(2), prostaglandin D(2) receptor (DP) and chemoattractant receptor-homologous molecule expressed on Th(2) cells (CRTH2), are both expressed on the surface of eosinophils, and CRTH2 has been demonstrated to mediate PGD(2)-induced eosinophil mobilization in vitro. However, it has not yet been determined whether PGD(2) and its receptors mediate in vivo eosinophil trafficking into the airways or other organs. We demonstrated that intratracheal administration of PGD(2) in rats pretreated with systemic interleukin-5 (IL-5) injection induced marked airway eosinophilia, determined by the differential counts of cells in bronchoalveolar lavage (BAL) fluid and lung histology, within 2 h. Systemic IL-5 alone significantly increased the number of eosinophils in the peripheral blood but showed no effect on airway eosinophilia. Three CRTH2-specific agonists (13,14-dihydro-15-keto-PGD(2), 11-deoxy-11-methylene-15-keto-PGD(2), and indomethacin) demonstrated equivalent induction of BAL eosinophilia to that of PGD(2), but a DP agonist (BW 245C [5-(6-carboxyhexyl)-1-(3-cyclohexyl-3-hydroxypropyl)-hydantoin]) or a thromboxane A(2) receptor (TP) agonist ([1S-1alpha,2beta(5Z), 3alpha(1E,3R*),4alpha)]-7-[3-(3-hydroxy-4-(4'-iodophenoxy)-1-butenyl)-7-oxabicyclo-[2.2.1]heptan-2-yl]-5-heptenoic acid) showed no effect. PGD(2) or CRTH2 agonist-induced BAL eosinophilia was almost completely inhibited by pretreatment with a CRTH2/TP antagonist, ramatroban [BAY-u3405; (+)-(3R)-3-(4-fluorobenzenesulfonamido)-1,2,3,4-tetra-hydrocarbazole-9-propionic acid], whereas a TP-specific antagonist, SQ29,548 (5-heptenoic, 7-[3-[[2-[(phenylamino)carbonyl]hydrazino]methyl]-7-oxabicyclo[2.2.1]-hept-2-yl]-[1S-[1alpha,2alpha(Z),3alpha,4alpha]]), or a DP-specific antagonist, BW A868C [3-benzyl-5-(6-carboxyhexyl)-1-(2-cyclohexy-2-hydroxyethylamino)-hydantoin], did not inhibit the effects of PGD(2). These results suggest that CRTH2 plays a significant role in the eosinophil trafficking from the bloodstream into the airways in PGD(2)-related airway inflammation.
Shiraishi
Yoshiki
Y
Division of Pulmonary Medicine, Department of Medicine, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan. ko-asano@qa2.so-net.ne.jp
Asano
Koichiro
K
Nakajima
Takeshi
T
Oguma
Tsuyoshi
T
Suzuki
Yusuke
Y
Shiomi
Tetsuya
T
Sayama
Koichi
K
Niimi
Kyoko
K
Wakaki
Misa
M
Kagyo
Junko
J
Ikeda
Eiji
E
Hirai
Hiroyuki
H
Yamaguchi
Kazuhiro
K
Ishizaka
Akitoshi
A
D000818:Animals; D018893:Bronchoalveolar Lavage; D004305:Dose-Response Relationship, Drug; D015848:Interleukin-5 / Q000494:pharmacology; D008297:Male; D015230:Prostaglandin D2 / Q000494:pharmacology*; D011657:Pulmonary Eosinophilia / Q000139:chemically induced* / Q000473:pathology; D051381:Rats; D011914:Rats, Inbred BN; D011971:Receptors, Immunologic / Q000502:physiology*; D011982:Receptors, Prostaglandin / Q000502:physiology*
D015848:Interleukin-5; D011971:Receptors, Immunologic; D011982:Receptors, Prostaglandin; D015230:Prostaglandin D2; C036293:prostaglandin D2 receptor