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.

Journal article

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 (K(i) = 0.013 μM), rat recombinant DP₂ (K(i) = 0.003 μM), and human native DP₂ (Th2 cell membranes; K(i) = 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 (pK(B) = 7.9) and human whole blood (pK(B) = 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.

Authors: Pettipher, R; Vinall, S; Xue, L; Speight, G; Townsend, E

• Journal: Journal of pharmacology and experimental therapeutics
• Volume: 340
• Issue: 2
• Pages: 473-482
• Publication date: 2012-02-01
• DOI: 10.1124/jpet.111.187203
• EISSN: 1521-0103
• ISSN: 0022-3565
• Language: English
• Keywords: Binding, Competitive; Cell Shape; Th2 Cells; Culture Media, Conditioned; Radioligand Assay; Mast Cells; Receptors, Prostaglandin; Recombinant Proteins; Eosinophilia; Lymphocyte Activation; Prostaglandin Antagonists; Interleukin-13; Apoptosis; Leukotriene B4; Pulmonary Eosinophilia; Humans; Calcium Signaling; Cell Membrane; Interleukin-5; Guinea Pigs; Transfection; Quinolines; Indoleacetic Acids; Receptors, Immunologic; CHO Cells; Rats, Sprague-Dawley; Animals; Prostaglandin D2; Eosinophils; Chemokine CCL11; Chemotaxis; Complement C5a; Arachidonic Acids; Cricetinae; Rats