Multimeric immunotherapeutic complexes activating natural killer cells towards HIV-1 cure

BackgroundCombination antiretroviral therapy (cART) has dramatically extended the life expectancy of people living with HIV-1 and improved their quality of life. There is nevertheless no cure for HIV-1 infection since HIV-1 persists in viral reservoirs of latently infected CD4+ T cells. cART does not eradicate HIV-1 reservoirs or restore cytotoxic natural killer (NK) cells which are dramatically reduced by HIV-1 infection, and express the checkpoint inhibitors NKG2A or KIR2DL upregulated after HIV-1 infection. Cytotoxic NK cells expressing the homing receptor CXCR5 were recently described as key subsets controlling viral replication.MethodsWe designed and evaluated the potency of Natural killer activating Multimeric immunotherapeutic compleXes, called as NaMiX, combining multimers of the IL-15/IL-15R alpha complex with an anti-NKG2A or an anti-KIR single-chain fragment variable (scFv) to kill HIV-1 infected CD4+ T cells. The oligomerization domain of the C4 binding protein was used to associate the IL-15/IL-15R alpha complex to the scFv of each checkpoint inhibitor as well as to multimerize each entity into a heptamer (alpha form) or a dimer (beta form). Each alpha or beta form was compared in different in vitro models using one-way ANOVA and post-hoc Tukey's tests before evaluation in humanized NSG tg-huIL-15 mice having functional NK cells.ResultsAll NaMiX significantly enhanced the cytolytic activity of NK and CD8+ T cells against Raji tumour cells and HIV-1+ ACH-2 cells by increasing degranulation, release of granzyme B, perforin and IFN-gamma. Targeting NKG2A had a stronger effect than targeting KIR2DL due to higher expression of NKG2A on NK cells. In viral inhibition assays, NaMiX initially increased viral replication of CD4+ T cells which was subsequently inhibited by cytotoxic NK cells. Importantly, anti-NKG2A NaMiX enhanced activation, cytotoxicity, IFN-gamma production and CXCR5 expression of NK cells from HIV-1 positive individuals. In humanized NSG tg-huIL-15 mice, we confirmed enhanced activation, degranulation, cytotoxicity of NK cells, and killing of HIV-1 infected cells from mice injected with the anti-NKG2A.alpha NaMiX, as compared to control mice, as well as decreased total HIV-1 DNA in the lung.ConclusionsNK cell-mediated killing of HIV-1 infected cells by NaMiX represents a promising approach to support HIV-1 cure strategies.

Automated summary

The study investigated the potency of NaMiX, a natural killer activating multimeric immunotherapeutic complex, in killing HIV-1 infected cells. NaMiX significantly enhanced the cytolytic activity of NK and CD8+ T cells against tumor cells and HIV-1 infected cells, and also improved the activation, cytotoxicity, IFN-γ production, and CXCR5 expression of NK cells. It is a promising approach for supporting HIV-1 cure strategies.