In Vitro Assay: The in vitro affinity of the compounds of the present invention for the CXCR1 and CXCR2 receptors was determined on a functional test of the .beta.-arrestin recruitment type after receptor activation.It was demonstrated that the activation by CXCL8 of the CXCR2 receptor in cells of the PathHunter HEK293-CXCR2 line or of the CXCR1 receptor in cells of the U2OS h CXCR1 .beta.-arrestin line results in the recruitment of .beta.-arrestin (Richardson et al. 2003 Role of the cytoplasmic tails of CXCR1 and CXCR2 in mediating leukocyte migration, activation, and regulation. J. Immunol. 170: 2904-2911.)In order to evaluate the direct interaction of the CXCR2 or CXCR1 receptor with .beta.-arrestin 2, a .beta.-arrestin 2 recruitment test for CXCR2 or CXCR1 based on of .beta.-galactosidase enzyme complementation (Olson K R, Eglen R M. Beta galactosidase complementation: a cell-based luminescent assay platform for drug discovery. Assay Drug Dev Technol. 2007 February; 5(1); 137-44).
FLIPR Assay: The experiments were carried out on the FLIPR TETRA.RTM. platform from Molecular Devices. After the basal level had been read, the compounds were added to the cells expressing the chemokine receptor of interest and the agonist activity was read at 10 seconds. After a further incubation for 10 minutes, the cells were activated, with a concentration equivalent to the AC80, using a reference agonist in order to detect whether this compound exhibits antagonist activity.Each cell line expressing a chemokine receptor was established on the basis of the Chem-1 cell stably expressing the recombinant form of the chemokine receptor and also an associated G protein, with the aim of coupling the receptor to the calcium signalling pathway. 21 receptors belonging to the chemokine receptor family (CCRs and CXCRs) were analyzed. All the CXCR2 antagonists were tested in a dose-dependent manner and the concentration corresponding to 50% inhibition of the response was determined (IC.sub.50).
In Vitro Assay: The in vitro affinity of the compounds of the present invention for the CXCR1 and CXCR2 receptors was determined on a functional test of the .beta.-arrestin recruitment type after receptor activation.It was demonstrated that the activation by CXCL8 of the CXCR2 receptor in cells of the PathHunter HEK293-CXCR2 line or of the CXCR1 receptor in cells of the U2OS h CXCR1 .beta.-arrestin line results in the recruitment of .beta.-arrestin (Richardson et al. 2003 Role of the cytoplasmic tails of CXCR1 and CXCR2 in mediating leukocyte migration, activation, and regulation. J. Immunol. 170: 2904-2911.)In order to evaluate the direct interaction of the CXCR2 or CXCR1 receptor with .beta.-arrestin 2, a .beta.-arrestin 2 recruitment test for CXCR2 or CXCR1 based on of .beta.-galactosidase enzyme complementation (Olson K R, Eglen R M. Beta galactosidase complementation: a cell-based luminescent assay platform for drug discovery. Assay Drug Dev Technol. 2007 February; 5(1); 137-44).
FLIPR Assay: The experiments were carried out on the FLIPR TETRA.RTM. platform from Molecular Devices. After the basal level had been read, the compounds were added to the cells expressing the chemokine receptor of interest and the agonist activity was read at 10 seconds. After a further incubation for 10 minutes, the cells were activated, with a concentration equivalent to the AC80, using a reference agonist in order to detect whether this compound exhibits antagonist activity.Each cell line expressing a chemokine receptor was established on the basis of the Chem-1 cell stably expressing the recombinant form of the chemokine receptor and also an associated G protein, with the aim of coupling the receptor to the calcium signalling pathway. 21 receptors belonging to the chemokine receptor family (CCRs and CXCRs) were analyzed. All the CXCR2 antagonists were tested in a dose-dependent manner and the concentration corresponding to 50% inhibition of the response was determined (IC.sub.50).