CCR5 Antagonist Td0232 In Vitro Pharmacodynamics Of

CCR5, one of the coreceptors of HIV–1, is a new target of anti-HIV therapy. We identified TD0232, a small molecule CCR5 antagonist, by [(35)^S]–GTPγS binding assay and studied its inhibitory effect on CCR5 and antiviral activity in vitro. This compound was a specific antagonist of CCR5 as determined in multiple chemokine-stimulated [(35)^S]–GTPγS binding assay. It could inhibit [(35)^S]–GTPγS binding to CCR5 induced by RANTES, MIP–1αand MIP–1βwith IC50 (mean 50% inhibitory concentrations) of 2.9, 0.6 and 0.7nM, respectively. TD0232 blocked the binding of RANTES to CCR5 with IC₅₀ of 2nM. Moreover, TD0232 strongly inhibited RANTES-induced calcium mobilization and chemotaxis of Chinese Hamster Ovary cells stably expressing CCR5 with IC50 of 78.9nM and 3.0nM, respectively. 1μM of TD0232 can completely inhibit internalization of not CXCR4 but CCR5 induced by agonist. However, neither CXCR4 nor CCR5 could internalize when treated with TD0232 only. In vitro, TD0232 had potent antiviral activity against HIV-1 R5 strains, including two primary HIV-1 isolates (HIV–l_HNz2 and HIV–l₂₀₆₇₈) and one lab adapted strain (HIV–l_JR-FL). The IC₅₀S of TD0232 on replication of these strains in human peripheral blood mononuclear cells were 4, 3 and 25nM, respectively. However, TD0232 could not inhibit HIV–l_NL4-3, a lab-adapted X4 strain, even at the concentration of 600nM. TD0232 had no evident cytotoxity on CHO/CCR5, Jurkat and L02 cells by MTT assay. On the basis of its mechanism of action on CCR5 and potent antiviral activity, TD0232 is a promising new candidate for therapeutic intervention of HIV infection.