Targeting Macrophage Histone H3 Modification as a Leishmania Strategy to Dampen the NF-κB/NLRP3-Mediated Inflammatory Response

Aberrant macrophage activation during intracellular infection generates immunopathologies that can cause severe human morbidity. A better understanding of immune subversion strategies and macrophage phenotypic and functional responses is necessary to design host-directed intervention strategies. Here, we uncover a fine-tuned transcriptional response that is induced in primary and lesional macrophages infected by the parasite Leishmania amazonensis and dampens NF-kappa B and NLRP3 inflammasome activation. Subversion is amastigote-specific and characterized by a decreased expression of activating and increased expression of de-activating components of these pro-inflammatory pathways, thus revealing a regulatory dichotomy that abrogates the anti-microbial response. Changes in transcript abundance correlate with histone H3K9/14 hypoacetylation and H3K4 hypo-trimethylation in infected primary and lesional macrophages at promoters of NF-kappa B-related, pro-inflammatory genes. Our results reveal a Leishmania immune subversion strategy targeting host cell epigenetic regulation to establish conditions beneficial for parasite survival and open avenues for host-directed, anti-microbial drug discovery.