Inhibitor of apoptosis, IAP, genes play a critical role in the survival of HIV-infected macrophages

Latent viral reservoirs of HIV-1 that persist despite antiretroviral therapy (ART) are major barriers for a successful cure. Macrophages serve as viral reservoirs due to their resistance to apoptosis and HIV-cytopathic effects. We have previously shown that inhibitor of apoptosis proteins (IAPs) confer resistance to HIV-Vpr-induced apoptosis in normal macrophages. Herein, we show that second mitochondrial activator of caspases (SMAC)-mimetics (SM) specifically induce apoptosis of monocyte-derived macrophages (MDMs) infected in vitro with a R5-tropic laboratory strain expressing heat stable antigen, and GFP-expressing HIV, chronically infected U1 cells, and ex-vivo derived MDMs from naive and ART-treated HIV patients. SM-induced cell death was found to be mediated by IAPs using IAP siRNAs, was independent of endogenously produced TNFα and was attributed to the concomitant downregulation of IAP-1/2 and the receptor interacting protein kinase-1 degradation following HIV infection. Altogether, modulation of the IAP pathways may be a potential strategy for selective killing of HIV-infected macrophages in vivo.