Histone deacetylase inhibition reduces deleterious cytokine release induced by ingenol stimulation

Abstract

IntroductionThough antiretroviral therapy has led to viral suppression and increased quality of life for patients living with HIV-1, strategies to eliminate the HIV-1 latent reservoir are still necessary to eliminate HIV. Latency reversal with superior latency reversal agents (LRAs) such as protein kinase C (PKC) agonists is a promising strategy for unveiling and eliminating the latent HIV-1 reservoir. However, PKC agonists induce T cell activation and deleterious pro- inflammatory cytokine production. Secondary pharmacological agents combined with LRAs have been previously shown to reduce deleterious pro-inflammatory cytokine secretion without inhibiting HIV-1 viral reactivation. Histone deacetylase inhibitors (HDACi) are also known for inhibiting deleterious pro-inflammatory cytokines in the context of graft-versus-host disease and rheumatoid arthritis in addition to being known to synergize with PKC agonists. In this study we investigated whether HDACi and other epigenetic modifiers could decrease PKC- induced pro-inflammatory cytokines secretion while simultaneously synergizing with the PKC agonists Ingenol-3,20-dibenzoate, to enhance latency reversal.MethodsWe screened an epigenetic modifier library in health donor human peripheral blood mononuclear cells (PBMCs) to identify compounds (‘hits’) that reduced intracellular IL-6 pro-inflammatory cytokine production induced by PKC agonist Ingenol-3,20-dibenzoate. We then further tested reducers of intracellular IL-6 (‘hits’) for their ability to synergize with Ingenol-3,20-dibenzoate in the J-LAT 10.6 model of HIV-1 latency. The most promising epigenetic modifier from both screens, the HDACi Panobinostat, was then further tested for its ability to reduce pro-inflammatory cytokines and synergize with Ingenol-3,20-dibenzoate.ResultsWe show that co-treatment with Ingenol-3,20-dibenzoate and Panobinostat reduces pro-inflammatory cytokines and enhances latency reversal in vitro. Panobinostat suppressed pro-inflammatory cytokine production when combined with Ingenol-3,20- dibenzoate ex vivo when using aviremic patient cells, but antagonized Ingenol-3,20-dibenzoate dependent latency reversal ex vivo.ConclusionThe combination of Panobinostat and Ingenol-3,20-dibenzoate reduces deleterious cytokine production but is not a suitable latency reversal combination therapy.

Impact of IL-15 and latency reversing agent combinations in the reactivation and NK cell-mediated suppression of the HIV reservoir

“…Remarkably, we also found that the combination of IL-15 + PRO displayed an outstanding latency reversal activity, in most donors outperforming the effect of PHA that, so far, has been considered one of the maximal HIV inducers. The here observed inefficacy of HDACis at reactivating HIV is in agreement with various studies [46][47][48][49] but also in apparent contrast with other reports showing HDACi-induced latency reversal 8,35,[50][51][52] , though different results can be explained by differing study designs. Herein, we did not use T cell expanding, differentiating, or pro-survival procedures that might have contrasted pro-apoptotic effects of HDACis in previous studies.…”

“…In addition, we evaluated the production of p24 HIV protein rather than accumulation of HIV transcripts because these latter may not be fully processed and competent for translation of viral proteins, as recently shown for both pan-and class I selective-HDACis 43,46 , hence may not measure complete latency reversal. While HDACi + IL-15 combinations have not been previously examined, studies in which HDACi were combined with PKCas to reactivate latent HIV have produced conflicting results showing either co-operation/synergism 47,[53][54][55] or antagonism 8,49,51 , which again might be related to differences in the experimental procedures.…”