PT  - JOURNAL ARTICLE
AU  - Pettipher, Roy
AU  - Vinall, Shân L.
AU  - Xue, Luzheng
AU  - Speight, Graham
AU  - Townsend, Elizabeth R.
AU  - Gazi, Lucien
AU  - Whelan, Cliff J.
AU  - Armer, Richard E.
AU  - Payton, Mark A.
AU  - Hunter, Michael G.
TI  - Pharmacologic Profile of OC000459, a Potent, Selective, and Orally Active D Prostanoid Receptor 2 Antagonist That Inhibits Mast Cell-Dependent Activation of T Helper 2 Lymphocytes and Eosinophils
AID  - 10.1124/jpet.111.187203
DP  - 2012 Feb 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 473--482
VI  - 340
IP  - 2
4099  - http://jpet.aspetjournals.org/content/340/2/473.short
4100  - http://jpet.aspetjournals.org/content/340/2/473.full
SO  - J Pharmacol Exp Ther2012 Feb 01; 340
AB  - D prostanoid receptor 2 (DP2) [also known as chemoattractant receptor-homologous molecule expressed on T helper 2 (Th2) cells (CRTH2)] is selectively expressed by Th2 lymphocytes, eosinophils, and basophils and mediates recruitment and activation of these cell types in response to prostaglandin D2 (PGD2). (5-Fluoro-2-methyl-3-quinolin-2-ylmethylindo-1-yl)-acetic acid (OC000459) is an indole-acetic acid derivative that potently displaces [3H]PGD2 from human recombinant DP2 (Ki = 0.013 μM), rat recombinant DP2 (Ki = 0.003 μM), and human native DP2 (Th2 cell membranes; Ki = 0.004 μM) but does not interfere with the ligand binding properties or functional activities of other prostanoid receptors (prostaglandin E1–4 receptors, D prostanoid receptor 1, thromboxane receptor, prostacyclin receptor, and prostaglandin F receptor). OC000459 inhibited chemotaxis (IC50 = 0.028 μM) of human Th2 lymphocytes and cytokine production (IC50 = 0.019 μM) by human Th2 lymphocytes. OC000459 competitively antagonized eosinophil shape change responses induced by PGD2 in both isolated human leukocytes (pKB = 7.9) and human whole blood (pKB = 7.5) but did not inhibit responses to eotaxin, 5-oxo-eicosatetraenoic acid, or complement component C5a. OC000459 also inhibited the activation of Th2 cells and eosinophils in response to supernatants from IgE/anti-IgE-activated human mast cells. OC000459 had no significant inhibitory activity on a battery of 69 receptors and 19 enzymes including cyclooxygenase 1 (COX1) and COX2. OC000459 was found to be orally bioavailable in rats and effective in inhibiting blood eosinophilia induced by 13,14-dihydro-15-keto-PGD2 (DK-PGD2) in this species (ED50 = 0.04 mg/kg p.o.) and airway eosinophilia in response to an aerosol of DK-PGD2 in guinea pigs (ED50 = 0.01 mg/kg p.o.). These data indicate that OC000459 is a potent, selective, and orally active DP2 antagonist that retains activity in human whole blood and inhibits mast cell-dependent activation of both human Th2 lymphocytes and eosinophils.