Project description:Interplay between metabolic state of the cell and its ability to undergo immunological activation has been recently recognized as a treasure chest of novel fundamental regulatory principles. Itaconate, and its membrane permeable derivative dimethyl itaconate (DI) were recently shown to selectively inhibit subset of cytokines during macrophage activation (e.g. Il1b, il6, Il12b but not TNF), yet the precise mechanism of this effect remained unclear. We find that selectivity of DI action stems from the inhibitory effects of electrophilic stress exerted by DI on IkB-zeta protein translation, leading to selective control of the secondary wave of Nfkb-signaling. Mechanistically, DI leads to glutathione depletion and subsequent activation of both Nrf2-dependent and Nrf2-independent stress responses. We find that IkB-zeta regulation is carried out in Nrf2-independent manner, and identify Atf3 as a key mediator of DI effects on IkB-zeta/IL6. This inhibitory effect is conserved across species and cell types, as evident from inhibition of IkB-zeta production in activating human monocytes and IL-17A stimulated keratinocytes of both human and mice. Finally, DI administration in vivo ameliorated IL17/IkB-zeta-driven skin pathology in the mouse model of psoriasis, highlighting therapeutic potential of this regulatory pathway.
Project description:Remodeling of the tricarboxylic acid (TCA) cycle is a metabolic adaptation mechanism accompanying inflammatory macrophage activation. During this process, endogenous metabolites can adopt regulatory roles that govern specific aspects of inflammatory response, as recently shown for succinate, which regulates the downstream pro-inflammatory IL-1β-HIF1a axis. Itaconate is one of the most highly induced metabolites in activated macrophages, yet its functional significance remains unknown. Here, we show that itaconate modulates macrophage metabolism and effector functions via its effect on succinate dehydrogenase, by inhibiting conversion of succinate to fumarate. Through this action, itaconate exerts anti-inflammatory effects when administered in vitro and in vivo during macrophage activation and ischemia-reperfusion injury. Using newly generated Irg1-/- mice, which lack the ability to produce itaconate, we show that endogenous itaconate regulates succinate levels and function, changes in mitochondrial respiration, and inflammatory cytokine production during macrophage activation. These studies highlight itaconate as a major physiological regulator of the global metabolic rewiring and effector functions of inflammatory macrophages. Experiment 1: mature WT BMDM were treated for 12h with 0.25 mM dimethyl itaconate (DI) or vehicle (Unst) and then stimulated with LPS (E. coli 0111:B4; 100 ng/ml, 4h) (DI+LPS; LPS); Experiment 2: mature Irg1-/- BMDM were stimulated with LPS (E. coli 0111:B4; 100 ng/ml) and murine recombinant IFNg (50 ng/ml) for 24h.
Project description:Metabolic regulation recently emerged as a novel powerful principle guiding immune responses. The natural metabolite itaconate and its membrane permeable derivative dimethyl itaconate (DI) were recently shown to selectively inhibit a subset of cytokines during macrophage activation, yet the precise mechanism of this effect remained unclear. We show here that itaconate/DI react with glutathione and subsequently induce both Nrf2-dependent and Nrf2-independent stress responses. We find that the striking selectivity of DI action stems from the inhibitory effects of electrophilic stress on IKBZ protein translation, leading to the inhibition of only the secondary wave of NF-KB signaling. We find that IKBZ regulation occurs in an Nrf2-independent manner, and identify ATF3 as a key mediator of the immunosuppression.
Project description:Chronic Lymphocytic Leukemia (CLL) is strictly dependent on the complex interplay between the intrinsic features of the leukemic cells and microenvironmental stimulations including inflammatory stimuli by Toll Like Receptors (TLR) which protect CLL cells from drug induced apoptosis by upregulating NFKBIZ, an atypical co-transcription factor. To face the challenge of targeting transcription factors, we exploited the capacity of Dimethyl Itaconate (DI), an electrophilic synthetic derivative of Itaconate, to block NFKBIZ acting as anti-inflammatory agent. Primary CLL cells isolated from the peripheral blood of patients, leukemic splenocytes isolated from TCL1 transgenic mice, and circulating leukocytes isolated from healthy donors were treated in vitro with increasing concentrations of DI either alone or in combination with the TLR ligands. DI abrogated the induction of NFKBIZ as well as its target genes IL6 and IL10. Remarkably, DI reduced metabolic activation and cell viability of leukemic cells even if added after a robust TLR pre-stimulation; in contrast, no toxic effect was evident in normal leukocytes including T- and B-lymphocytes. DI induced apoptosis of malignant cells by reducing BCL-XL and MCL1 levels while inducing PARP cleavage. RNA sequencing highlighted that DI abrogated the TLR9-mediated upregulation of transcripts related to the metabolism of rRNAs, interferon and cytokine signaling. Notably, in addition to the expected electrophilic stress signature observed after DI treatment, novel pathways emerged including the downregulation of distinct MHC class II complex genes. In conclusion, DI not only abrogated the pro-inflammatory effects of TLR stimulation but also targeted a specific vulnerability in CLL cells.
Project description:Chronic Lymphocytic Leukemia (CLL) is strictly dependent on the complex interplay between the intrinsic features of the leukemic cells and microenvironmental stimulations including inflammatory stimuli by Toll Like Receptors (TLR) which protect CLL cells from drug induced apoptosis by upregulating NFKBIZ, an atypical co-transcription factor. To face the challenge of targeting transcription factors, we exploited the capacity of Dimethyl Itaconate (DI), an electrophilic synthetic derivative of Itaconate, to block NFKBIZ acting as anti-inflammatory agent. Primary CLL cells isolated from the peripheral blood of patients, leukemic splenocytes isolated from TCL1 transgenic mice, and circulating leukocytes isolated from healthy donors were treated in vitro with increasing concentrations of DI either alone or in combination with the TLR ligands. DI abrogated the induction of NFKBIZ as well as its target genes IL6 and IL10. Remarkably, DI reduced metabolic activation and cell viability of leukemic cells even if added after a robust TLR pre-stimulation; in contrast, no toxic effect was evident in normal leukocytes including T- and B-lymphocytes. DI induced apoptosis of malignant cells by reducing BCL-XL and MCL1 levels while inducing PARP cleavage. RNA sequencing highlighted that DI abrogated the TLR9-mediated upregulation of transcripts related to the metabolism of rRNAs, interferon and cytokine signaling. Notably, in addition to the expected electrophilic stress signature observed after DI treatment, novel pathways emerged including the downregulation of distinct MHC class II complex genes. In conclusion, DI not only abrogated the pro-inflammatory effects of TLR stimulation but also targeted a specific vulnerability in CLL cells.
Project description:Analysis of gene expression in human PBMCs infected with influenza A virus or Mock and treated with Itaconic acid, Dimethyl itaconate or 4-Octyl itaconate to investigate the effects itaconate have on transcriptional response in human PBMCs. We particularly looked at anti-inflammatory effects of itaconate in inflammation followed by Influenza A virus infection.
Project description:Analysis of gene expression in A549 cells infected with influenza A virus or Mock and treated with Itaconic acid (IA), or Dimethyl itaconate (DI) to investigate the effects itaconate have on transcriptional response in A549 cells. We particularly looked at anti-inflammatory effects of itaconate in inflammation followed by Influenza A virus infection.
Project description:Analysis of gene expression indTHP-1 cells infected with influenza A virus or Mock and treated with Itaconic acid (IA), or Dimethyl itaconate (DI) to investigate the effects itaconate have on transcriptional response in dTHP-1 cells. We particularly looked at anti-inflammatory effects of itaconate in inflammation followed by Influenza A virus infection.
Project description:Itaconic acid and its variant Dimethyl itaconate (DI) have shown an anti-inflammatory effect in different human cell lines and PBMCs during Infleunza A virus (IAV) infection. In this experiment, we further explored which cell types in PBMCs respond to IAV infection and DI treatment.