Histone deacetylase inhibition reduces deleterious cytokine release induced by ingenol stimulation

Abstract

Latency reversing agents (LRAs), such as protein kinase C (PKC) agonists, constitute a promising strategy for exposing and eliminating the HIV-1 latent reservoir. PKC agonists activate NF-κB and induce deleterious pro-inflammatory cytokine production. Adjuvant pharmacological agents, such as ruxolitinib, a JAK inhibitor, have previously been combined with LRAs to reduce deleterious pro-inflammatory cytokine secretion without inhibiting HIV-1 reactivation in vitro. Histone deacetylase inhibitors (HDACi) are known to dampen pro-inflammatory cytokine secretion in the context of other diseases and synergize with LRAs to reactivate latent HIV-1. This study investigates whether a panel of epigenetic modifiers, including HDACi, could dampen PKC-induced pro-inflammatory cytokine secretion during latency reversal. We screened an epigenetic modifier library for compounds that reduced intracellular IL-6 production induced by the PKC agonist Ingenol-3,20-dibenzoate. We further tested the most promising epigenetic inhibitor class, HDACi, for their ability to reduce pro-inflammatory cytokines and reactivate latent HIV-1 ex vivo. We identified nine epigenetic modulators that reduced PKC-induced intracellular IL-6. In cells from aviremic individuals living with HIV-1, the HDAC1-3 inhibitor, suberohydroxamic acid (SBHA), reduced secretion of pro-inflammatory cytokines TNF-α, IL-5, IL-2r, and IL-17 but did not significantly reactivate latent HIV-1 when combined with Ingenol-3,20-dibenzoate. Combining SBHA and Ingenol-3,20-dibenzoate reduces deleterious cytokine production during latency reversal but does not induce significant viral reactivation in aviremic donor PBMCs. The ability of SBHA to reduce PKC-induced pro-inflammatory cytokines when combined with Ingenol-3,20-dibenzoate suggests SBHA can be used to reduced PKC induced pro-inflammatory cytokines but not to achieve latency reversal in the context of HIV-1.

Keywords: Cytokine; HDACi; HIV-1; Ingenol-3,20-dibenzoate; Latency reversing agent; Suberohydroxamic acid.