Selective Induction of Programmed-cell Death in HIV-infected Macrophages

• Main Author: Caballero, Ramon Edwin
• Other Authors: Kumar, Ashok
• Format: Others
• Language: en
• Published: Université d'Ottawa / University of Ottawa 2018
• Subjects: HIV; Macrophages; Apoptosi; IAPs
• Online Access: http://hdl.handle.net/10393/37650; http://dx.doi.org/10.20381/ruor-21914

In order to achieve cure for HIV-1 infection in patients undergoing suppressive antiretroviral therapy, eradication of all latently infected reservoirs of the virus is required. The focus of HIV cure is predominantly centred on the elimination of latently infected memory T cells, while information on possible elimination of infected macrophages is lacking. Macrophages support continuous virus replication without succumbing to cytopathic effects of HIV-1. Recently, our laboratory has shown a protective role for cellular inhibitor of apoptosis proteins (IAPs) 1/2 in macrophages against Vpr-induced apoptosis. Depletion of cIAP1/2 by Smac mimetics (SM) reverse the IAP-mediated protection and sensitize macrophages to Vpr-induced cell death. My research aims to understand the role IAPs play in apoptotic resistance of HIV-infected macrophages. I hypothesized that ablation of cIAP1/2 by SM may induce apoptosis in HIV-infected macrophages. My results show that SM does not induce cell death in uninfected or healthy macrophages, but induces cell death in chronically infected U1 cells, in vitro infected monocyte-derived macrophages, and ex vivo derived HIV-infected macrophages from HIV-infected individuals. SM induce cell death of infected myeloid cells through apoptosis and not through necroptosis. Moreover, SM-induced apoptosis is independent of TNFα and other endogenously secreted cytokines. In vitro infection of monocyte-derived macrophages leads to the downregulation of RIPK1, RIPK3, and TRAF-1. Interestingly, necrostatin-1-mediated RIPK1- inhibition does not affect viability of healthy macrophages, but in combination with IAP degradation by SM leads to significant induction of apoptosis. This suggests a key role for RIPK1 in SM-induced apoptosis of HIV-infected macrophages. Altogether, the results from this project suggest that modulation of the IAP-associated signalling pathways by SM may be a potential strategy for selective killing of HIV-infected macrophages.