Dessilly, G. | bioRxiv Science

bioRxiv2022

Natural Killer activating Multimeric Immunotherapeutic compleXes (NaMiX) induce cytotoxic activity and killing of HIV-1 infected cells

HIV-1 persists in viral reservoirs of latently infected CD4+ T cells containing integrated replication-competent viral DNA. Combined Antiretroviral Therapy (cART) does not eradicate HIV-1 reservoirs and treatment interruption will ultimately lead to viral load rebound. HIV-1 infection dramatically reduces the proportion of functional NK cell subsets and increases the expression of the checkpoint inhibitors NKG2A and KIR2DL. In this regard, we developed novel recombinant molecules combining multimers of the IL-15/IL-15R complex with the single-chain fragment variables (scFvs) of NKG2A or KIR2DL, and named them as Natural killer activating Multimeric immunotherapeutic compleXes (NaMiX). NaMiX significantly improved the cytotoxic activity of NK cells against HIV-1 positive ACH-2 cells and resistant Raji cancer cells by increasing their degranulation capacity, release of granzyme B, perforin and IFN-{gamma} expression. Targeting the NKG2A receptor had a stronger effect compared to the targeting of the KIR2DL receptor due to its higher expression on NK cells. In a viral inhibition assay using CD4+ T cells from HIV-1 positive patients under cART, NaMiX initially increased viral replication which was subsequently inhibited by stimulated NK cells. In humanized NSG tg-huIL-15 mice showing functional NK cells, we observed enhanced activation, degranulation and killing by NK cells from the spleen of mice treated with anti-NKG2A NaMiX compared to the cells of control mice previously infected with HIV-1 and treated with cART. Although NaMiX did not delay viral load rebound after treatment interruption in a first attempt, it tend to decrease total HIV-1 DNA in the lungs of the mice. Blocking the inhibitory receptor NKG2A in combination with targeted multimers of IL-15 on NK cells could therefore be a promising immunotherapeutic strategy towards HIV-1 functional cure.

immunology↗

bioRxiv2020

HIV-1 and HIV-2 differentially regulate NF-κB activity during the late stages of the replication cycle through BST-2/tetherin antagonism

HIV-2 is the second causative agent of AIDS and is commonly considered as an attenuated form of retroviral infection. Most of HIV-2-infected individuals display a slow-progressing disease, lower viral loads and a stronger immunological control of viral infection as compared with HIV-1-infected patients. The main hypothesis that could explain the difference of disease progression between HIV-1 and HIV-2 implies a more efficient T cell-mediated immunity in the control of HIV-2 infection. Herein, we investigate the effects of the HIV-2 envelope glycoprotein (Env) and its antitetherin function in the NF-{kappa}B signaling pathway during single-round infection of CD4+ T cells. First, we report an essential role of the Env cytoplasmic tail (CT) in the activation of this signaling pathway and we also demonstrate that the HIV-2 Env CT activates NF-{kappa}B in a TRAF6-dependent but TAK1-independent manner. Further, we show that HIV-2 reference strains and clinical isolates are unable to completely inhibit NF-{kappa}B mainly via the Env-mediated BST-2/tetherin antagonism in the late stages of the viral replication cycle in CD4+ T cells, in striking contrast to the HIV-1 Vpu-mediated counteraction of tetherin. We observe that this inability of HIV-2 to suppress NF-{kappa}B signaling pathway promotes stimulation of numerous genes involved in the antiviral immune response, such as il-6, il-21 and ifn-{beta} genes. Therefore, HIV-1 and HIV-2 differentially regulate the NF-{kappa}B-induced antiviral immune response mainly through the BST-2/tetherin antagonism. These new insights highlight molecular mechanisms determining, at least partly, the distinct immune control and disease outcomes of HIV-1 and HIV-2 infections. IMPORTANCEThis study explores how HIV-1 and HIV-2 diverge in their regulation of the NF-{kappa}B signaling pathway. We revealed that HIV-2 fails to completely inhibit NF-{kappa}B activity, thereby inducing a stronger antiviral response than HIV-1. We demonstrated that the ability to antagonize the cellular restriction factor BST-2/tetherin largely governs the regulation of the NF-{kappa}B pathway: at the late stages of the viral replication cycle, HIV-1 Vpu blocks this pathway whereas HIV-2 Env does not. We also demonstrated that several NF-{kappa}B-targeted genes are upregulated in CD4+ T cells infected with HIV-2, but not with HIV-1. This stronger NF-{kappa}B-induced antiviral response may explain the better immune control of HIV-2 infection and the differences between HIV-1 and HIV-2 pathogenesis. Moreover, we observed in this study that non-pathogenic isolates of HIV-2 have an impaired NF-{kappa}B inhibitory capacity compared to pathogenic ones.

microbiology↗