Immunometabolic profiling ofin vitroandex vivo Leishmania-infected macrophages (LIMs) reveals unique polarization and bioenergetic signatures

Abstract

Macrophages are the major host cells of the protozoan parasite Leishmania in mammalian infection. These key innate immune cells display remarkable phenotypic plasticity ranging from pro-inflammatory M1 to anti-inflammatory M2 macrophages that can control infection and tissue homeostasis, respectively. It has been recognized that Leishmania exploits macrophage phenotypic plasticity to establish chronic infection. However, the current notion that these parasites simply trigger an M2-like phenotype seems over-simplified considering the immunopathology observed during leishmaniasis, is which often characterized by a mixed Th1/Th2 immune response. Here we combined a series of systems-level analyses to shed new light on the phenotype of Leishmania-infected macrophages (LIMs). Immunometabolic profiling by RNAseq, quantitative RT-qPCR, cytokine immunoassays, and bioenergetic flux analysis of Leishmania amazonensis-infected bone marrow-derived macrophages (BMDMs) revealed a highly complex, mixed polarization phenotype and a unique bioenergetic signature. In vitro LIMs were characterized by (i) co-expression of both M1 and M2 markers at RNA and protein levels, (ii) expression changes of a unique set of inflammatory genes (e.g. RELA, IGFBP3, VEGFA), and (iii) modulation of metabolic gene expression, including up regulation of glycolytic genes. This LIMs-specific phenotype persisted for at least 30 days and was confirmed in vivo in lesion-isolated LIMs. Likewise, in vitro LIMs showed a mixed bioenergetic profile, increasing both glycolytic activity and oxidative phosphorylation (OXPHOS) compared to uninfected, nonpolarized macrophages (M0). Surprisingly, the elimination of intracellular parasites using the fast-acting, anti-leishmanial drug L-leucine-O-methyl ester (LME) enhanced both bioenergetic pathways to levels comparable to M1 (glycolysis) and M2 (OXPHOS) macrophages as soon as one hour after treatment, suggesting that L. amazonensis limits in real-time energy metabolism and ATP production in LIMs. In conclusion, L. amazonensis infection establishes a mixed, immunometabolomic polarization profile in infected BMDMs and lesional macrophages that on one hand can promote an M1-regulated Th1 response required for the recruitment of new host cells to infected tissues, while at the same time promoting an M2 phenotype that dampens pro-inflammatory immune-signaling and shields intracellular parasites from leishmanicidal Nitric Oxide (NO).

MAPPING CHANGES OF MIRNA-MRNA NETWORKS INLEISHMANIA-INFECTEDMACROPHAGES PREDICTS REGULATORY MIRNA-TF LOOPS AS NOVEL TARGETS OF PARASITE IMMUNE SUBVERSION

“…Applying dual RNAseq analysis on mRNA and miRNA fractions obtained from L. amazonensis -infected and uninfected BMDMs allowed us unprecedented insight into the possible role of the host cell noncoding RNome as a novel target for parasite immune subversion. Based on our computational analyses, the observed miRNA expression changes are predicted to affect the abundance of a large array of transcripts that establish the immune-metabolomic expression profile and cellular phenotype characteristic of L. amazonensis infected macrophages (Zhang et al . 2022).…”

Leishmania amazonensiscontrols macrophage-regulated cell death to establish chronic infectionin vitroandin vivo

“…The mechanisms underlying Leishmania -mediated subversion of TF-dependent expression control are different from the strategies developed by other pathogens, which include NF-κB-mediated induction of anti-RCD genes or degradation of pro-RCD mediators (Abu-Zant et al, 2007; Robinson and Aw, 2016). Our recent reports on epigenetic and metabolic reprogramming of LIMs (Lecoeur et al, 2020a; Zhang et al, 2022) suggest that changes in TF expression may be regulated by DNA and histone modifications, non-coding RNAs, or changes in host cell glycolytic energy-production and expression of intermediate metabolites that have been linked to RCD resistance (Huang et al, 2015; Huang et al, 2013; Li et al, 2021; Pradelli et al, 2010). Our study opens important new questions on (i) the parasite-released factors that modulate epigenetic, transcriptional and metabolic control in infected LIMs, (ii) the complex interplay between these levels of control in establishing the anti-inflammatory and anti-RCD LIMs phenotype, and (iii) the possibility to design novel host-directed strategy that can rescue the pro-inflammatory and pro-RCD pathways to eliminate intracellular parasites and clear chronic infection.…”

“…This strategy not only safeguards the pathogens’ metabolic niche, but also avoids exposure to anti-microbial activities triggered by dying cells. This phenomenon is very well illustrated by intracellular parasites of the genus Leishmania that infect innate immune system such as macrophages (Mϕs) and dendritic cells (Liu and Uzonna, 2012) and exploits the phenotypic plasticity of these cells to establish a unique immuno-metabolic phenotype that favour parasite survival and chronic infection (Arango Duque and Descoteaux, 2015; Ferreira et al, 2021; Lecoeur et al, 2021; Saunders and McConville, 2020; Van Assche et al, 2011; Zhang et al, 2022).…”