title: Pharmacological characterization of CXC chemokine receptor 3 ligands and a small molecule antagonist.
abstract: The CXC chemokine receptor 3 (CXCR3) is predominantly expressed on T helper type 1 (Th1) cells that are involved in inflammatory diseases. The three CXCR3 ligands CXCL9, CXCL10, and CXCL11 are produced at sites of inflammation and elicit migration of pathological Th1 cells. Here, we are the first to characterize the pharmacological potencies and specificity of a CXCR3 antagonist, N-1R-[3-(4-ethoxy-phenyl)-4-oxo-3,4-dihydro-pyrido[2,3-d]pyrimidin-2-yl]-ethyl-N-pyridin-3-ylmethyl-2-(4-fluoro-3-trifluoromethyl-phenyl)-acetamide (NBI-74330), from the T487 small molecule series. NBI-74330 demonstrated potent inhibition of [(125)I]CXCL10 and [(125)I]CXCL11 specific binding (K(i) of 1.5 and 3.2 nM, respectively) and of functional responses mediated by CXCR3, such as ligand-induced guanosine 5'-O-(3-[(35)S]thio)triphosphate ([(35)S]GTPgammaS) binding, calcium mobilization, and cellular chemotaxis (IC(50) of 7 to 18 nM). NBI-74330 was selective for CXCR3 because it showed no significant inhibition of chemotactic responses to other chemokines and did not inhibit radioligand binding to a panel of nonchemokine G-protein coupled receptors. There was a striking difference in potencies among the three CXCR3 ligands, with CXCL11 >> CXCL10 > CXCL9. A comparison of the rank order of K(i) values with the rank order of monocyte production levels of these three ligands revealed a precise inverse correlation, suggesting that the weaker receptor affinities of CXCL9 and CXCL10 were physiologically compensated for by an elevated expression, perhaps to maintain effectiveness of each ligand under physiological conditions.
authors.affiliation: Neurocrine Biosciences, Inc., San Diego, CA 92130, USA. cheise@neurocrine.com
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Heise
authors.forename: Anil
authors.initials: A
authors.lastname: Pahuja
authors.forename: Sarah C
authors.initials: SC
authors.lastname: Hudson
authors.forename: Monica S
authors.initials: MS
authors.lastname: Mistry
authors.forename: Amy L
authors.initials: AL
authors.lastname: Putnam
authors.forename: Molly M
authors.initials: MM
authors.lastname: Gross
authors.forename: Peter A
authors.initials: PA
authors.lastname: Gottlieb
authors.forename: Warren S
authors.initials: WS
authors.lastname: Wade
authors.forename: Mehrak
authors.initials: M
authors.lastname: Kiankarimi
authors.forename: David
authors.initials: D
authors.lastname: Schwarz
authors.forename: Paul
authors.initials: P
authors.lastname: Crowe
authors.forename: Albert
authors.initials: A
authors.lastname: Zlotnik
authors.forename: David G
authors.initials: DG
authors.lastname: Alleva
mesh_terms: D000081:Acetamides / Q000378:metabolism / Q000494:pharmacology*; D045744:Cell Line, Tumor; D054357:Chemokine CXCL10; D054371:Chemokine CXCL11; D054370:Chemokine CXCL9; D019743:Chemokines, CXC / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D008024:Ligands; D011743:Pyrimidines / Q000378:metabolism / Q000494:pharmacology*; D054367:Receptors, CXCR3; D019707:Receptors, Chemokine / Q000037:antagonists & inhibitors* / Q000378:metabolism*
chemical_list: D000081:Acetamides; C114753:CXCL10 protein, human; C515202:CXCL11 protein, human; C080810:CXCL9 protein, human; C515187:CXCR3 protein, human; D054357:Chemokine CXCL10; D054371:Chemokine CXCL11; D054370:Chemokine CXCL9; D019743:Chemokines, CXC; D036341:Intercellular Signaling Peptides and Proteins; D008024:Ligands; C501976:NBI-74330; D011743:Pyrimidines; D054367:Receptors, CXCR3; D019707:Receptors, Chemokine; D016244:Guanosine 5'-O-(3-Thiotriphosphate)