BAY u3405

Kinase experiment:

CRTH2 transfectants are resuspended in binding buffer (50 mM Tris-HCl, pH 7.4, 40 mM MgCl2, 0.1% BSA, 0.1% NaN3). Cell suspension (2×105 cells), 3H-labeled PGD2, and various concentrations of Ramatroban (0.1 nM, 1 nM, 10 nM, 100 nM, 1 μM and 10 μM) are then mixed in a 96-well U-bottomed polypropylene plate and incubated in a final volume of 100 μL for 60 min at room temperature. After incubation, the cell suspension is transferred to a filtration plate and washed three times with binding buffer. Scintillant is added to the filtration plate, and radioactivity remaining on the filter is measured by a scintillation counter. Nonspecific binding is determined by incubating the cell suspension and 3H-labeled PGD2 in the presence of 1 μM unlabeled PGD2[2].

Cell experiment:

Human eosinophils are purified and resuspended in migration buffer (20 mM HEPES, pH 7.6, 0.1% BSA, Hanks' solution) at a density of 6 ×106 cells/mL. Fifty microliters of the cell suspension (3×105 cells/well) is then dispensed into the upper chamber of a 96-well type chemotaxis chamber (pore diameter=5 μm), and 30 μL of ligand solution is added to the lower chamber. Cells are preincubated with various concentrations of Ramatroban (0.1 nM, 1 nM, 10 nM, 100 nM, 1 μM and 10 μM) or BWA868C at 37°C for 10 min. The migration assays are performed in a humidified incubator at 37°C, 5% CO2 for 2 h. The number of cells migrating into the lower chamber is counted[2].

Animal experiment:

Mice[3]Five micrograms of LPS (closed columns) or saline (open columns) are intraperitoneally injected into CRTH2+/+ mice. CRTH2+/+ mice are pretreated intraperitoneally for 1 h with 30 mg/kg Ramatroban.

References:

[1]. Stearns BA, et al. Novel tricyclic antagonists of the prostaglandin D2 receptor DP2 with efficacy in a murine modelof allergic rhinitis. Bioorg Med Chem Lett. 2009 Aug 15;19(16):4647-51.
[2]. Sugimoto H, et al. An orally bioavailable small molecule antagonist of CRTH2, ramatroban (BAY u3405), inhibits prostaglandin D2-induced eosinophil migration in vitro. J Pharmacol Exp Ther. 2003 Apr;305(1):347-52.
[3]. Haba R, et al. Central CRTH2, a second prostaglandin D2 receptor, mediates emotional impairment in the lipopolysaccharide and tumor-induced sickness behavior model. J Neurosci. 2014 Feb 12;34(7):2514-23.