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. 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: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:Macrophages play critical roles in inflammation and tissue homeostasis, and their functions are regulated by various autocrine, paracrine, and endocrine factors. We have previously shown that CTRP6, a secreted protein of the C1q family, targets both adipocytes and macrophages to promote obesity-linked inflammation in adipose tissue. However, the gene programs and signaling pathways directly regulated by CTRP6 in macrophage remain unknown. Here, we combine transcriptomic and phosphoproteomic analyses to show that CTRP6 activates inflammatory gene programs and signaling pathways in bone marrow-derived macrophages (BMDMs). Treatment of BMDMs with CTRP6 upregulates proinflammatory, and suppresses the anti-inflammatory, gene expression. We show that CTRP6 activates p44/42-MAPK, p38-MAPK, and NF-κB signalings to promote inflammatory cytokine secretion from BMDMs, and that pharmacologic inhibition of these signaling pathways largely abolish the effects of CTRP6. Pretreatment of BMDMs with CTRP6 further augments LPS-induced inflammatory signaling and cytokine secretion from BMDMs. Consistent with the metabolic phenotype of proinflammatory M1-like macrophages, CTRP6 treatment induces a shift toward aerobic glycolysis and lactate production, reduces oxidative metabolism, and elevates mitochondrial ROS production in BMDMs. We use a Ctrp6 knockout mouse model to further confirm the physiologic relevance of our in vitro findings. BMDMs from CTRP6-deficient mice are less inflammatory at baseline and show a marked suppression of LPS-induced inflammatory gene expression and cytokine secretion. Loss of CTRP6 in mice also dampens LPS-induced inflammation and hypothermia. Collectively, we provide mechanistic evidence that CTRP6 regulates macrophage function, and neutralizing CTRP6 activity may have beneficial effects in reducing inflammation.
Project description:<p>The mechanisms by which macrophage metabolism is regulated and the effects of metabolism on diseases remain largely unknown. We show here that TGF-β regulates the glycolysis of macrophages independently of inflammatory cytokine production, and thus affects the survival in experimental sepsis. Specifically, TGF-β increased expression and activity of phosphofructokinase-1 liver type (PFKL) in macrophages and thus promoted their glycolysis during cell activation, yet paradoxically suppressed the production of proinflammatory cytokines in the same macrophages. The upregulation of glycolysis was mediated by a mTOR-c-MYC dependent pathway, whereas the inhibition of cytokines was ascribed to the activation of SMAD3 and a downregulated activation of the pro-inflammatory transcription factors AP-1, NFkB and STAT1. Importantly, in an LPS-induced endotoxemia and CLP-sepsis models, TGF-β enhancement of macrophage glycolysis led to a decreased survival in mice, which was associated with increased blood coagulation. Analysis of cohorts of patients with sepsis and covid-19 revealed that the expression of PFKL, TGF-β receptor TGFBRI and coagulation factor F13A1 in myeloid cells positively correlated with the progression of the disease. Thus, TGF-β is emerging as a critical cytokine regulating macrophage metabolism and could serve as a therapeutic target in patients with sepsis.</p>
Project description:Nrf2-mediated anti-inflammation through transcriptional repression of proinflammatory cytokine genesNrf2-mediated anti-inflammation through transcriptional repression of proinflammatory cytokine genes
Project description:The canonical role IL-4 is to induce M2 macrophage polarization. Herein we report that in addition to its canonical role, IL-4 also induces non-canonical pro-inflammatory response via epigenetic memory. Although IL-4 stimulated macrophages do not produce classic proinflammatory cytokines such as IL-6 and IL-1b, they produce heightened proinflammatory cytokine upon LPS stimulation.
Project description:The canonical role of IL-4 is to induce M2 macrophage polarization. Herein we report that in addition to its canonical role, IL-4 also induces non-canonical pro-inflammatory response via epigenetic memory. Although IL-4 stimulated macrophages do not produce classic proinflammatory cytokines such as IL-6 and IL-1β, they produce heightened proinflammatory cytokine upon LPS stimulation.
Project description:Macrophages generate mitochondrial reactive oxygen and electrophilic species (mtROS, mtRES) as antimicrobials during Toll-like receptor (TLR)-dependent inflammatory responses. Whether mitochondrial stress caused by these molecules impacts macrophage function is unknown. Here, we demonstrate that both pharmacologically- and lipopolysaccharide (LPS)-driven mitochondrial stress in macrophages triggers a stress response called mitohormesis. LPS-driven mitohormetic stress adaptations occur as macrophages transition from an LPS-responsive to LPS-tolerant state where stimulus-induced proinflammatory gene transcription is impaired, suggesting tolerance is a product of mitohormesis. Indeed, like LPS, hydroxyestrogen-triggered mitohormesis suppresses mitochondrial oxidative metabolism and acetyl-CoA production needed for histone acetylation and proinflammatory gene transcription, and is sufficient to enforce an LPS-tolerant state. Thus, mtROS and mtRES are TLR-dependent signaling molecules that trigger mitohormesis as a negative feedback mechanism to restrain inflammation via tolerance. Moreover, bypassing TLR signaling and pharmacologically triggering mitohormesis represents a novel anti-inflammatory strategy that co-opts this stress response to impair epigenetic support of proinflammatory gene transcription by mitochondria.
Project description:Macrophages generate mitochondrial reactive oxygen and electrophilic species (mtROS, mtRES) as antimicrobials during Toll-like receptor (TLR)-dependent inflammatory responses. Whether mitochondrial stress caused by these molecules impacts macrophage function is unknown. Here, we demonstrate that both pharmacologically- and lipopolysaccharide (LPS)-driven mitochondrial stress in macrophages triggers a stress response called mitohormesis. LPS-driven mitohormetic stress adaptations occur as macrophages transition from an LPS-responsive to LPS-tolerant state where stimulus-induced proinflammatory gene transcription is impaired, suggesting tolerance is a product of mitohormesis. Indeed, like LPS, hydroxyestrogen-triggered mitohormesis suppresses mitochondrial oxidative metabolism and acetyl-CoA production needed for histone acetylation and proinflammatory gene transcription, and is sufficient to enforce an LPS-tolerant state. Thus, mtROS and mtRES are TLR-dependent signaling molecules that trigger mitohormesis as a negative feedback mechanism to restrain inflammation via tolerance. Moreover, bypassing TLR signaling and pharmacologically triggering mitohormesis represents a novel anti-inflammatory strategy that co-opts this stress response to impair epigenetic support of proinflammatory gene transcription by mitochondria.