Open AccessBiased small‐molecule ligands for selective inhibition of HIV‐1 cell entry via CCR5
Author(s) -
Berg Christian,
Spiess Katja,
Lüttichau Hans R.,
Rosenkilde Mette M.
Publication year - 2016
Publication title -
pharmacology research and perspectives
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.975
H-Index - 27
ISSN - 2052-1707
DOI - 10.1002/prp2.262
Subject(s) - maraviroc , ccr5 receptor antagonist , small molecule , luciferase , chemistry , cell fusion , viral entry , lipid bilayer fusion , chemokine receptor ccr5 , microbiology and biotechnology , effector , receptor , chemokine receptor , biology , biochemistry , virology , transfection , cell , viral replication , virus , chemokine , human immunodeficiency virus (hiv) , gene
Since the discovery of HIV 's use of CCR 5 as the primary coreceptor in fusion, the focus on developing small‐molecule receptor antagonists for inhibition hereof has only resulted in one single drug, Maraviroc. We therefore investigated the possibility of using small‐molecule CCR 5 agonists as HIV ‐1 fusion inhibitors. A virus‐free cell‐based fusion reporter assay, based on mixing “effector cells” (expressing HIV Env and luciferase activator) with “target cells” (expressing CD 4, CCR 5 wild type or a selection of well‐described mutations, and luciferase reporter), was used as fusion readout. Receptor expression was evaluated by ELISA and fluorescence microscopy. On CCR 5 WT , Maraviroc and Aplaviroc inhibited fusion with high potencies ( EC 50 values of 91 and 501 nM , respectively), whereas removal of key residues for both antagonists (Glu283Ala) or Maraviroc alone (Tyr251Ala) prevented fusion inhibition, establishing this assay as suitable for screening of HIV entry inhibitors. Both ligands inhibited HIV fusion on signaling‐deficient CCR 5 mutations (Tyr244Ala and Trp248Ala). Moreover, the steric hindrance CCR 5 mutation (Gly286Phe) impaired fusion, presumably by a direct hindrance of gp120 interaction. Finally, the efficacy switch mutation (Leu203Phe) – converting small‐molecule antagonists/inverse agonists to full agonists biased toward G‐protein activation – uncovered that also small‐molecule agonists can function as direct HIV ‐1 cell entry inhibitors. Importantly, no agonist‐induced receptor internalization was observed for this mutation. Our studies of the pharmacodynamic requirements for HIV ‐1 fusion inhibitors highlight the possibility of future development of biased ligands with selective targeting of the HIV – CCR 5 interaction without interfering with the normal functionality of CCR 5.