Nrf2 suppresses macrophage inflammatory response by blocking proinflammatory cytokine transcription
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ABSTRACT: Nrf2 (NF-E2-related factor-2) transcription factor regulates oxidative/xenobiotic stress response and also represses inflammation. However, the mechanisms how Nrf2 alleviates inflammation are still unclear. Here, we demonstrate that Nrf2 interferes with lipopolysaccharide-induced transcriptional upregulation of proinflammatory cytokines, including IL-6 and IL-1β. ChIP-seq and ChIP-qPCR analyses revealed that Nrf2 binds to the proximity of these genes in macrophages and inhibits RNA Pol II recruitment. Further, we found that Nrf2-mediated inhibition is independent of the Nrf2 binding motif and reactive oxygen species level. Murine inflammatory models further demonstrated that Nrf2 interferes with IL6 induction and inflammatory phenotypes in vivo. Thus, contrary to the widely accepted view that Nrf2 suppresses inflammation through redox control, we demonstrate here that Nrf2 opposes transcriptional upregulation of proinflammatory cytokine genes. This study identifies Nrf2 as the upstream regulator of cytokine production and establishes a molecular basis for an Nrf2-mediated anti-inflammation approach. Gene expression in BMDMs obtained from wild-type and Keap1-CKO mice. In Keap1-CKO (Keap1 flox/flox::LysM-Cre) BMDMs, Nrf2 transcription factor is activated due to Keap1-deficiency. BMDMs were obtained by a culture of bone marrow cells in the presence of M-CSF for7 days. M1-activated BMDMs were obtained by stimulation with LPS and IFNg for 6 hours, while M2-activated BMDMs were obtained by a stimulation with IL-4 for 6 hours. Two independent BMDM cultures were performed, and each experiment contains samples obtained from one wild-type and one Keap1-CKO mice, respectively.
Project description:Genetic versus chemoprotective activation of Nrf2 signaling: overlapping yet distinct hepatic gene expression profiles between Keap1 knockout and triterpenoid treated mice; Loss of Nrf2 signaling increases susceptibility to acute toxicity, inflammation, and carcinogenesis in mice due to the inability to mount adaptive responses. By contrast, disruption of Keap1 (a cytoplasmic modifier of Nrf2 turnover) protects against these stresses in mice; although dominant negative mutations in Keap1 have been identified recently in some human cancers. Global characterization of Nrf2 activation is important to exploit this pathway for chemoprevention in healthy, yet at-risk individuals and also to elucidate the consequences of hijacking the pathway in Keap1-mutant human cancers. This analysis also enables a global characterization of the pharmacodynamic action of CDDO-Im at a low dose that is relevant to chemoprevention. Experiment Overall Design: Liver-targeted conditional Keap1-null (CKO) mice provide a model of genetic activation of Nrf2 signaling. By coupling global gene expression analysis of CKO mice with analysis of pharmacologic activation using the synthetic oleanane triterpenoid CDDO-Im, we are able to gain insight into pathways affected by Nrf2 activation. CDDO-Im is an extremely potent activator of Nrf2 signaling. CKO mice were used to identify genes modulated by genetic activation of Nrf2 signaling. The CKO response was compared to hepatic global gene expression changes in wild-type mice treated with CDDO-Im at a maximal Nrf2 activating dose. n=3/group, male 9 week old mice were used. Mice were treated with a single dose of vehicle (10% Cremophor-EL, 10% DMSO, and PBS) or 30 umol CDDO-Im/kg body weight by gavage and sacrificed 6 h later.
Project description:To identify Nrf1-dependent and Nrf2-dependent genes in the liver, we examined the gene expression profiles of Nrf1 Alb-CKO, Nrf2 knockout and Keap1 knockdown mouse livers by microarray analyses. Total RNAs from Nrf1dN/-::Alb-Cre, Nrf1dN/+, Nrf2-/-, Nrf2+/+, Keap1KD/- and Keap1KD/+ mouse livers were used for the microarray analyses.
Project description:Nrf2 (NF-E2-related factor-2) transcription factor regulates oxidative/xenobiotic stress response and also represses inflammation. However, the mechanisms how Nrf2 alleviates inflammation are still unclear. Here, we demonstrate that Nrf2 interferes with lipopolysaccharide-induced transcriptional upregulation of proinflammatory cytokines, including IL-6 and IL-1β. ChIP-seq and ChIP-qPCR analyses revealed that Nrf2 binds to the proximity of these genes in macrophages and inhibits RNA Pol II recruitment. Further, we found that Nrf2-mediated inhibition is independent of the Nrf2 binding motif and reactive oxygen species level. Murine inflammatory models further demonstrated that Nrf2 interferes with IL6 induction and inflammatory phenotypes in vivo. Thus, contrary to the widely accepted view that Nrf2 suppresses inflammation through redox control, we demonstrate here that Nrf2 opposes transcriptional upregulation of proinflammatory cytokine genes. This study identifies Nrf2 as the upstream regulator of cytokine production and establishes a molecular basis for an Nrf2-mediated anti-inflammation approach.
Project description:To identify Nrf1-dependent and Nrf2-dependent genes in the liver, we examined the gene expression profiles of Nrf1 Alb-CKO, Nrf2 knockout and Keap1 knockdown mouse livers by microarray analyses.
Project description:Heme-activation of NRF2 is a strong anti-inflammatory signal in macrophages, and analyses in this study indicated that the expressed transcriptome in heme-TAMs was consistently enriched for NRF2 target genes. We have therefore delineated the role of NRF2 in a series of experiments with Nrf2 knockout BMDMs, leading to a locked NRF2-inactive state, and macrophages with a knockout of the cytoplasmic NRF2 capture protein KEAP1, leading to a locked NRF2-active state, irrespective of the presence or absence of heme. To demonstrate that activated NRF2 is sufficient to drive heme-TAM transformation, we analyzed Keap1 knockout macrophages.
Project description:BMDMs or iMACs were generated via differentiation of bone marrow cells or immortalized precursors, respectively, in culture media containing m-CSF for 7 day. Upon differentiation, BMDMs or iMacs were left untreated or stimulated as described below. 1) BMDM WT were stimulated with IFNa, LPS, PGE2, IL-4, IL-10, LPS+PGE2, LPS+IL-4, LPS+IL-10, IFNa+PGE2, IFNa+IL-10: each condition in duplicate. This experiment was performed to investigate transcriptional cross-antagonism in the concomitant presence of pro-inflammatory (LPS or IFNa) and anti-inflammatory stimuli (IL-4, IL-10, or PGE2). 2) BMDM WT were stimulated with LPS, in the presence or absence of PFI-1 (Brd2/4 inhibitor) or SGC-CBP30 (CBP/p300 inhibitor): each condition in triplicate. This experiment was performed to define pro-inflammatory genes dependent or not on chromatin remodeling for their induction. 3) BMDM Mef2C/D proficient (Vav-Cre) or BMDM Mef2C/D KO (obtained by crossing Mef2d-/- Mef2cfl/fl with Vav-Cre mice) were stimulated with LPS, PGE2, or LPS+PGE2: each condition in triplicate. This experiment was performed to investigate the role of MEF2C-D on LPS transcritptional response. 4) BMDM WT were pretreated for 40 minutes with an anti-IL10R antibody or the corresponding isotope control, and then left untreated or stimulated with LPS, PGE2 or LPS+PGE2: each condition in duplicate. This experiment was performed to investigate the crosstalk between IL-10 and PGE2. 5) BMDM WT were left untreated or stimulated with PGE2, LPS, LPS+PGE2, or LPS+PGE2+IFNb. In the latter condition, IFNb was added 1 hour after the beginning of the costimulation: each condition in triplicate. This experiment was performed to asses the impact of PGE2 into the LPS-mediated IFNb induction. 5) MEF2A-deficient iMac clones (D7, A7, A8, C7) and MEF2A-proficient (referred to as wild-type) iMac clones (NE, B3 and D10) were generated via CRISPR/Cas9 and stimulated or not with LPS: each condition in single. This experiment was performed to investigate the role of MEF2A on LPS transcritptional response.
Project description:IL-10 or IL-6 stimulation of control 129xC57BL/6 murine bone marrow derived macrophages in the presence of LPS. We used microarrays to detail the global programme of gene expression changes in response to IL-6 or IL-10 stimulation in the presence of lipopolysaccharide. BMDMs were isolated from control, IL-6-/-, and IL-10-/- mice on a 129XBL/6 mixed background mice and differentiated in the presence of CSF-1 for 6-7 days. Cells were scraped and plated in 6 well plates at 2x10e6/well. Cells were washed with complete DMEM and rested for 1-2 hr before stimulation with combinations of IL-10 (10 ng/ml), IL-6 (2 ng/ml) or LPS (100 ng/ml) for 45 min or 180 mins. Complete biological replicates were performed. Experiment Overall Design: Data sets from wild-type, IL-10-/- and IL-6-/- BMDMs treated with IL-6 or IL-10 in the presence of LPS over time
Project description:Alternative macrophages are critical in parasites defense, the resolution of inflammation and wound healing. RNA modifications, which are defined as post-transcriptional changes in the chemical composition of RNA molecules, are involved in the immune response.Among tRNA-modifying enzymes which target the tRNA anticodon, Elongator and Cytosolic thiouridylase (Ctu)-1/2 complexes exclusively modify the wobble uridine (U34) base in cytosolic tRNAs. However, the full picture of how mRNA translational factors maintain protein synthesis accuracy and co-translational protein folding are far from being fully understood.To address this question,we evaluated the role of Elp3 on protein in the IL4 induced alternative bone marrow derived macrophages (BMDMs). The BMDMs from widetype and Elp3 myeloid specific knockout mice were treated by IL-4 for 24h or not. Then the aggregates were isolated from these BMDMs and performed by MS.
Project description:Keap1 overexpressed and Nrf2 depleted CL1-5 cells were used to identify genes regulated by Keap1/Nrf2 axis-dependent gene regulations We used microarrays to detail the global programme of gene expression underlying metastasis and identified distinct classes of Keap1/Nrf2-regulated genes during this process. CL1-5 cells stably expressed Keap1 expressing construct and Nrf2-specific shRNA were analyzed compared to control cells
Project description:To explore the spatiotemporal regulation of ASC speck formation and inflammasome activation, we infected primary WT and Asc–/– bone marrow-derived macrophages (BMDMs) with the bacterium Francisella novicida to induce AIM2 inflammasome activation and then performed ASC IP-MS to identify proteins that interacted with ASC. We compared the IP products between WT BMDMs and Asc–/– BMDMs, and found that many proteins specifically interacted with ASC.