Reactivation of HIV latency by a newly modified Ingenol derivative via protein kinase Cδ–NF-κB signaling

Abstract

Objective Although HAART effectively suppresses viral replication, it fails to eradicate latent viral reservoirs. The ‘shock and kill’ strategy involves the activation of HIV from latent reservoirs and targeting them for eradication. Our goal was to develop new approaches for activating HIV from latent reservoirs. Design We investigated capacity of Ingenol B (IngB), a newly modified derivative of Ingenol ester that was originally isolated from a Brazilian plant in Amazon, for its capacity and mechanisms of HIV reactivation. Methods Reactivation of HIV-1 by IngB was evaluated in J-Lat A1 cell culture model of HIV latency as well as in purified primary CD4+ T cells from long-term HAART-treated virologically-suppressed HIV-infected individuals. The underlining molecular mechanisms of viral reactivation were investigated using flow cytometry, RT-qPCR and chromatin immunoprecipitation. Results IngB is highly effective in reactivating HIV in J-Lat A1 cells with relatively low cellular toxicity. It is also able to reactivate latent HIV in purified CD4+ T cells from HAART-treated HIV-positive individuals ex vivo. Our data show that IngB may reactivate HIV expression by both activating protein kinase C (PKC)δ–nuclear factor kappalight-chain-enhancer of activated B cells (NF-κB) pathway and directly inducing NF-κB protein expression. Importantly, IngB has a synergistic effect with JQ1, a BET bromodomain inhibitor, in latent HIV reactivation. Conclusions IngB is a new promising compound to activate latent HIV reservoirs. Our data suggest that formulating novel derivatives from Ingenol esters may be an innovative approach to develop new lead compounds to reactivate latent HIV.

Targeting NF-κB Signaling with Protein Kinase C Agonists As an Emerging Strategy for Combating HIV Latency

“…54 Similar findings about the effects of IngB on HIV replication in cell culture models of HIV latency were reported, but involved the use of higher concentrations of IngB, up to 1 lM. 55 Interestingly, IngB also inhibited HIV replication by suppressing the expression of CD4, CCR5, and CXCR4.…”

“…52,53 Some of the ingenol derivatives, including ITA and I-3-A, enhanced HIV replication at nanomolar levels in chronically HIV-infected cells, depending on or independent of the PKC/NF-jB pathway. 52,53 We recently found that ingenol-3-hexanoate (IngB), a new ingenol compound from the Brazilian plant Euphorbia tirucalli, activated latent HIV LTR in the J-Lat cells in vitro as well as in U1 cells and was more potent than SAHA, JQ1, HMBA, or prostratin in reactivation of the provirus 54 ( Fig. 7).…”

“…However, IngB caused an increase in the expression of CD69, NF-jB, or P-TEFb proteins in CD4 + T cells at higher concentrations, raising some concerns about its potential side effects. 30,54,55 Gnidimacrin and other diterpenes Gnidimacrin reactivated latent HIV LTR in U1 and ACH2 cell culture models of HIV latency at picomolar concentrations. It inhibited HIV infection of T cell lines and primary PBMCs by down-modulating the expression of HIV coreceptors CCR5 or CXCR4.…”

Progress and challenges in the use of latent HIV-1 reactivating agents

“…A recent study found that a newly modified ingenol ester compound originally isolated from Euphorbia tirucalli, Ingenol B (IngB), reactivated latent viruses in J-Lat A1 cell lines and purified CD4 + T cells from HIV-1 infected patients under longterm HAART [65] . IngB can effectively promote HIV transcription through activation of the protein kinase C (PKC) δ-Serine 664-NF-κB pathway or through a direct increase in NF-κB expression.…”

Progress Towards an HIV Cure: Update from the 2014 International AIDS Society Symposium

“…The first class of compounds, including prostratin, bryostatin, and ingenol, induces cellular protein kinase C (PKC) signaling leading to migration of active NF-jB into the cell nucleus, which in turn promotes initiation of HIV mRNA transcription. 15,22,23 The second class of compounds, including HMBA plus the JQ1, I-BET, and I-BET151 bromodomain and extraterminal (BET) inhibitors, all release active P-TEFb in the cell, which in turn binds the HIV Tat transcriptional activator protein to drive elongation of HIV mRNA transcripts. 24,25 Thus, both types of compounds drive different stages of HIV transcription to enhance HIV mRNA expression.…”