Inhibition of human immunodeficiency virus type 1 replication in latently infected cells by a novel IκB kinase inhibitor

In human immunodeficiency virus type 1 (HIV-1) latently infected cells, NF-kappa B plays a major role in the transcriptional induction of HIV-1 replication. Hence, downregulation of NF-kappa B activation has long been sought for effective anti-HIV therapy. Tumor necrosis factor alpha (TNF-alpha) stimulates I kappa B kinase (IKK) complex, a critical regulator in the NF-kappa B signaling pathway. A novel IKK inhibitor, ACHP {2-amino-6-[2-(cyclopropylmethoxy)-6-hydroxyphenyl] -4-piperidin-4-yl-nicotinonitrile}, was developed and evaluated as a potent and specific inhibitor for IKK-alpha and IKK-beta. In this study, we examined the ability of this compound to inhibit HIV-1 replication in OM10.1 cells latently infected with HIV. When these cells were pretreated with ACHP, TNF-alpha-induced HIV-1 replication was dramatically inhibited, as measured by the HIV p24 antigen levels in the culture supernatants. Its 50% effective concentration was approximately 0.56 mu M, whereas its 50% cytotoxic concentration was about 15 mu M. Western blot analysis revealed inhibition of I kappa B alpha phosphorylation, I kappa B alpha degradation, p65 nuclear translocation, and p65 phosphorylation. ACHP was also found to suppress HIV-1 long terminal repeat (LTR)-driven gene expression through the inhibition of NF-kappa B activation. Furthermore, ACHP inhibited TNF-alpha-induced NF-kappa B (p65) recruitment to the HIV-1 LTR, as assessed by chromatin immunoprecipitation assay. These findings suggest that ACHP acts as a potent suppressor of TNF-alpha-induced HIV replication in latently infected cells and that this inhibition is mediated through suppression of IKK activity.