Biological characterization of ligands targeting the human CC chemokine receptor 8 (CCR8) reveals the biased signaling properties of small molecule agonists

The human CC chemokine receptor 8 (CCR8) is a promising drug target for cancer immunotherapy and autoimmune disease. Besides viral chemokines, previous studies revealed diverse classes of CCR8-targeting small molecules. We characterized selection these CCR8 ligands (hCCL1, vCCL1, ZK756326, AZ6; agonists naphthalene-sulfonamide-based antagonist), in vitro cell-based assays (hCCL1AF647 binding, calcium mobilization, cellular impedance, cell migration, β-arrestin 1/2 recruitment), used pharmacological tools to determine G protein-dependent -independent signaling pathways elicited by ligands. Our data reveal differences CCR8-mediated induced chemokines versus molecules, which was most pronounced migration studies. Human CCL1 efficiently whereby Gβγ indispensable. In contrast, did not contribute other (vCCL1, AZ6). Although all tested were full significant contribution herein only apparent CCL1. Despite both Gαi- Gαq-signaling regulate intracellular Ca2+-release, impedance experiments showed that predominantly induce Gαi-dependent signaling. Finally, molecule displayed higher efficacy 1 recruitment, occurred independently Gαi Also this latter assay, hCCL1-induced activity dependent on Gβγ-signaling. study provides insight into function demonstrates differential activation different This reflects the ability molecules evoke subsets receptor’s repertoire, categorizes them as biased agonists.