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      Synergistic Reactivation of Latent HIV Expression by Ingenol-3-Angelate, PEP005, Targeted NF-kB Signaling in Combination with JQ1 Induced p-TEFb Activation

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          Although anti-retroviral therapy (ART) is highly effective in suppressing HIV replication, it fails to eradicate the virus from HIV-infected individuals. Stable latent HIV reservoirs are rapidly established early after HIV infection. Therefore, effective strategies for eradication of the HIV reservoirs are urgently needed. We report that ingenol-3-angelate (PEP005), the only active component in a previously FDA approved drug (PICATO) for the topical treatment of precancerous actinic keratosis, can effectively reactivate latent HIV in vitro and ex vivo with relatively low cellular toxicity. Biochemical analysis showed that PEP005 reactivated latent HIV through the induction of the pS643/S676-PKCδ/θ-IκBα/ε-NF-κB signaling pathway. Importantly, PEP005 alone was sufficient to induce expression of fully elongated and processed HIV RNAs in primary CD4+ T cells from HIV infected individuals receiving suppressive ART. Furthermore, PEP005 and the P-TEFb agonist, JQ1, exhibited synergism in reactivation of latent HIV with a combined effect that is 7.5-fold higher than the effect of PEP005 alone. Conversely, PEP005 suppressed HIV infection of primary CD4+ T cells through down-modulation of cell surface expression of HIV co-receptors. This anti-cancer compound is a potential candidate for advancing HIV eradication strategies.

          Author Summary

          Stable latent viral reservoirs in HIV infected individuals are rapidly reactivated following the interruption of anti-retroviral therapy (ART). Despite an early initiation of ART, viral reservoirs are established and persist as demonstrated in the case of the Mississippi baby and from recent studies of the SIV model of AIDS. Therefore, new strategies are needed for the eradication of the latent HIV reservoirs. We found that ingenol-3-angelate (PEP005), a member of the new class of anti-cancer ingenol compounds, effectively reactivated HIV from latency in primary CD4+ T cells from HIV infected individuals receiving ART. Importantly, a combination of PEP005 and JQ1, a p-TEFb agonist, reactivated HIV from latency at level on average 7.5-fold higher compared to PEP005 alone. The potency of synergistic effects of PEP005 and JQ1 provide novel opportunities for advancing HIV eradication strategies in the future. In summary, ingenols represent a new group of lead compounds for combating HIV latency.

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          Most cited references 48

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          Identification of a reservoir for HIV-1 in patients on highly active antiretroviral therapy.

          The hypothesis that quiescent CD4+ T lymphocytes carrying proviral DNA provide a reservoir for human immunodeficiency virus-type 1 (HIV-1) in patients on highly active antiretroviral therapy (HAART) was examined. In a study of 22 patients successfully treated with HAART for up to 30 months, replication-competent virus was routinely recovered from resting CD4+ T lymphocytes. The frequency of resting CD4+ T cells harboring latent HIV-1 was low, 0.2 to 16.4 per 10(6) cells, and, in cross-sectional analysis, did not decrease with increasing time on therapy. The recovered viruses generally did not show mutations associated with resistance to the relevant antiretroviral drugs. This reservoir of nonevolving latent virus in resting CD4+ T cells should be considered in deciding whether to terminate treatment in patients who respond to HAART.
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            HIV reproducibly establishes a latent infection after acute infection of T cells in vitro.

            The presence of latent reservoirs has prevented the eradication of human immunodeficiency virus (HIV) from infected patients successfully treated with anti-retroviral therapy. The mechanism of postintegration latency is poorly understood, partly because of the lack of an in vitro model. We have used an HIV retroviral vector or a full-length HIV genome expressing green fluorescent protein to infect a T lymphocyte cell line in vitro and highly enrich for latently infected cells. HIV latency occurred reproducibly, albeit with low frequency, during an acute infection. Clonal cell lines derived from latent populations showed no detectable basal expression, but could be transcriptionally activated after treatment with phorbol esters or tumor necrosis factor alpha. Direct sequencing of integration sites demonstrated that latent clones frequently contain HIV integrated in or close to alphoid repeat elements in heterochromatin. This is in contrast to a productive infection where integration in or near heterochromatin is disfavored. These observations demonstrate that HIV can reproducibly establish a latent infection as a consequence of integration in or near heterochromatin.
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              Stimulation of HIV-1-specific cytolytic T lymphocytes facilitates elimination of latent viral reservoir after virus reactivation.

              Highly active antiretroviral therapy (HAART) suppresses HIV-1 replication but cannot eliminate the virus because HIV-1 establishes latent infection. Interruption of HAART leads to a rapid rebound of viremia, so life-long treatment is required. Efforts to purge the latent reservoir have focused on reactivating latent proviruses without inducing global T cell activation. However, the killing of the infected cells after virus reactivation, which is essential for elimination of the reservoir, has not been assessed. Here we show that after reversal of latency in an in vitro model, infected resting CD4(+) T cells survived despite viral cytopathic effects, even in the presence of autologous cytolytic T lymphocytes (CTLs) from most patients on HAART. Antigen-specific stimulation of patient CTLs led to efficient killing of infected cells. These results demonstrate that stimulating HIV-1-specific CTLs prior to reactivating latent HIV-1 may be essential for successful eradication efforts and should be considered in future clinical trials. Copyright © 2012 Elsevier Inc. All rights reserved.

                Author and article information

                Role: Editor
                PLoS Pathog
                PLoS Pathog
                PLoS Pathogens
                Public Library of Science (San Francisco, CA USA )
                30 July 2015
                July 2015
                : 11
                : 7
                [1 ]Department of Medical Microbiology and Immunology, University of California, Davis, Davis, California, United States of America
                [2 ]Department of Medicine, University of California, San Francisco, San Francisco, California, United States of America
                [3 ]San Francisco Veterans Affairs Medical Center (VMAC), San Francisco, California, United States of America
                [4 ]Department of Physics, Williams College, Williamstown, Massachusetts, United States of America
                [5 ]Department of Molecular and Cellular Biology, University of California, Davis, Davis, California, United States of America
                [6 ]Department of Internal Medicine, Division of Infectious Diseases, University of California Davis Medical Center, Sacramento, California, United States of America
                Emory University, UNITED STATES
                Author notes

                The authors have declared that no competing interests exist.

                Conceived and designed the experiments: GJ SD. Performed the experiments: GJ EAM PK YT IC. Analyzed the data: GJ EAM PK DPW JKW SD. Contributed reagents/materials/analysis tools: YT JEKH. Wrote the paper: GJ JKW PK SD. Coordinated patient samples: AF GPM GRT.


                This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication

                Page count
                Figures: 12, Tables: 1, Pages: 27
                This study is supported by NIH grants DK61297, AI43274, and UC Davis Research Investments in Science and Engineering (RISE) grant to SD and a post-doctoral fellowship from CAPES/Brazil (BEX 2951/12-6) to EAM. PK is supported by the Swiss National Science Foundation (PBZHP3_147260). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
                Research Article
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                All relevant data are within the paper and its Supporting Information files.

                Infectious disease & Microbiology


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