Abstract

Cysteinyl leukotrienes (CysLTs) are potent inflammatory mediators that predominantly exert their effects by binding to cysteinyl leukotriene receptors of the G protein-coupled receptor family. CysLT receptor 2 (CysLT₂R), expressed in endothelial cells of some vascular beds, has been implicated in a variety of cardiovascular functions. Endothelium-specific overexpression of human CysLT₂R in transgenic mice (hEC-CysLT₂R) greatly increases myocardial infarction damage. Investigation of this receptor, however, has been hindered by the lack of selective pharmacological antagonists. Here, we describe the characterization of 3-(((3-carboxycyclohexyl)amino)carbonyl)-4-(3-(4-(4-phenoxybutoxy)phenyl)-propoxy)benzoic acid (BayCysLT₂) and explore the selective effects of this compound in attenuating myocardial ischemia/reperfusion damage and vascular leakage. Using a recently developed β-galactosidase–β-arrestin complementation assay for CysLT₂R activity (Mol Pharmacol 79:270–278, 2011), we determined BayCysLT₂ to be ∼20-fold more potent than the nonselective dual CysLT receptor 1 (CysLT₁R)/CysLT₂R antagonist 4-(((1R,2E,4E,6Z,9Z)-1-((1S)-4-carboxy-1-hydroxybutyl)-2,4,6,9-pentadecatetraen-1-yl)thio)benzoic acid (Bay-u9773) (IC₅₀ 274 nM versus 4.6 μM, respectively). Intracellular calcium mobilization in response to cysteinyl leukotriene administration showed that BayCysLT₂ was >500-fold more selective for CysLT₂R compared with CysLT₁R. Intraperitoneal injection of BayCysLT₂ in mice significantly attenuated leukotriene D₄-induced Evans blue dye leakage in the murine ear vasculature. BayCysLT₂ administration either before or after ischemia/reperfusion attenuated the aforementioned increased myocardial infarction damage in hEC-CysLT₂R mice. Finally, decreased neutrophil infiltration and leukocyte adhesion molecule mRNA expression were observed in mice treated with antagonist compared with untreated controls. In conclusion, we present the characterization of a potent and selective antagonist for CysLT₂R that is useful for discerning biological activities of this receptor.