IFN-γ and IL-4 regulate epigenetic modifiers in macrophages
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ABSTRACT: Interferon-γ (IFN-γ) or interleukin-4 (IL-4) prime macrophages towards classical (M1) or alternative (M2) activation, respectively. How IFN-γ and IL-4 prime epigenetic responses by altering expression of histone modifying enzymes and how this affects M1/M2 polarization is incompletely understood.
Project description:Macrophages are known to be polarized into inflammatory (M1) and immunoregulatory (M2) cells when they are stimulated by agonists such as IFN-gamma and IL-4, respectively. If circulating monocytes may be polarized in response to T cell signals is often misguidedly deduced from macrophage results. Here the transcriptional responses of human CD14+ monocytes to IFN-gamma and IL-4 were analyzed using whole genome microarrays. A principal component analysis and hierarchical clustering showed that monocyte and macrophage responses were distinct. Monocytes stimulated with IFN-gamma and IL-4 for 6 hours exhibited some features of macrophage polarization. Indeed, when 80 genes considered as M1 and M2 genes were analyzed, we found that M1 genes were modulated in response to IFN-gamma and that M2 genes were modulated in response to IL-4. The M1 polarization of monocytes was transient because only M2 genes were modulated when monocytes were stimulated with IFN-gamma and IL-4 for 18 hours. However, the activation of monocytes by IFN-gamma and IL-4 could not be reduced to M1/M2 polarization status. Indeed, monocytes exhibited early specific signatures composed of 46 and 39 up-regulated genes in response to IFN-gamma and IL-4, respectively, and a late signature common to both molecules that consisted of 57 up-regulated genes. Taken together, these results demonstrated the extreme plasticity of human monocytes and suggested the existence of a core transcriptional termination program. Using early and late signatures might be pertinent to investigate monocyte activation in inflammatory or infectious diseases. Monocytes were stimulated with IFN-gamma (20ng/mL) or IL-4 (20ng/mL) for 6 and 18 hours or culture for 6 and 18 hours without agonist (Unstimulated samples). Monocytes-derived-macrophages (MDM) stimulated with IFN-gamma and IL-4 for 18 hours were used as controls. Each microarray is derived from a single biological sample.
Project description:Macrophages are known to be polarized into inflammatory (M1) and immunoregulatory (M2) cells when they are stimulated by agonists such as IFN-gamma and IL-4, respectively. If circulating monocytes may be polarized in response to T cell signals is often misguidedly deduced from macrophage results. Here the transcriptional responses of human CD14+ monocytes to IFN-gamma and IL-4 were analyzed using whole genome microarrays. A principal component analysis and hierarchical clustering showed that monocyte and macrophage responses were distinct. Monocytes stimulated with IFN-gamma and IL-4 for 6 hours exhibited some features of macrophage polarization. Indeed, when 80 genes considered as M1 and M2 genes were analyzed, we found that M1 genes were modulated in response to IFN-gamma and that M2 genes were modulated in response to IL-4. The M1 polarization of monocytes was transient because only M2 genes were modulated when monocytes were stimulated with IFN-gamma and IL-4 for 18 hours. However, the activation of monocytes by IFN-gamma and IL-4 could not be reduced to M1/M2 polarization status. Indeed, monocytes exhibited early specific signatures composed of 46 and 39 up-regulated genes in response to IFN-gamma and IL-4, respectively, and a late signature common to both molecules that consisted of 57 up-regulated genes. Taken together, these results demonstrated the extreme plasticity of human monocytes and suggested the existence of a core transcriptional termination program. Using early and late signatures might be pertinent to investigate monocyte activation in inflammatory or infectious diseases.
Project description:Macrophage activation is required for the control of innate and adaptive immune responses. The classification in M1 and M2 macrophages based on a combination of small numbers of membrane and soluble markers is operational in murine and human macrophages. If this classification may be extended to circulating monocytes is not elucidated. To answer such question, human monocytes were stimulated for 6 and 18 hours with IFN-gamma and IL-4, two canonical agonists of M1/M2 polarization in macrophages, and gene expression programs were investigated with whole genome microarrays. The temporal analysis of these programs showed marked differences to both IFN-gamma and IL-4. In 6-h stimulated monocytes, gene categories related to inflammatory and immune responses were enriched, and these monocytes exhibited a M1 and M2 polarization in response to IFN-gamma and IL-4, respectively, as found in macrophages. In 18-h stimulated monocytes, the categories related to innate immunity and metabolic pathways were enriched in response to IFN-gamma and IL-4, whereas PPAR signaling pathway was specifically enriched in response to IL-4. In addition, the M1 and M2 polarization induced by IFN-gamma and IL-4, respectively, was replaced by an original transcriptional program that did not depend on IFN-gamma and IL-4. This program appeared as networks around chemokines, NF-kappaB/MAP kinase pathways and MHC class II molecules. These results clearly demonstrated that monocyte activation consisted of an early polarized stage likely involved in effector responses and a delayed stage that may regulate host responses. The establishment of databases on human circulating monocytes using high throughput methods may be critical for pathophysiological and clinical non-invasive studies. Peripheral blood mononuclear cells (PBMCs) were isolated from leukopacks from normal blood donor buffy coats (Etablissement Français du Sang, Marseille, France) by Ficoll density gradient
Project description:In the context of T1 Diabetes, pro-inflammatory cytokines IL-1β and IFN-γ are known to contribute to β-cell apoptosis; The measurement of mRNA expression following β-cell exposure to these cytokines gives a picture of the changes in gene expression characterizing the path to β-cell dysfunction and death. Human islets were isolated and exposed (or not) to IL-1β and IFN-γ. The samples were collected at various time points for profiling with Affymetrix arrays. These measurements were performed three times.
Project description:To understand the molecular signature of the IL-10/IL-18 polarized macrophages, we performed transcriptome analysis for mouse BMDMs polarized with PBS (Naïve), IFN-γ (classic M1 stimulator, M1, 20ng/ml), IL-4 (alternative M2 stimulator, M2, 20ng/ml), IL-10 (M10, 2000ng/ml), IL-18 (M18, 2000ng/ml) or IL-10 and IL-18 (M1018, 2000ng/ml each). These data suggest that IL-10 and IL-18 cooperatively modulate a set of gene expressions and pathway activities in macrophages and contribute to a distinct polarization state.
Project description:Complete polarization of macrophages towards an M1-like proinflammatory and antimicrobial state requires combined action of IFN-γ and LPS. Synergistic activation of canonical inflammatory NF-κB target genes by IFN-γ and LPS is well appreciated, but less is known about whether IFN-γ negatively regulates components of the LPS response, and how this affects polarization. A combined transcriptomic and epigenomic approach revealed that IFN-γ selectively abrogates LPS-induced feedback and select metabolic pathways by suppressing TLR4-mediated activation of gene enhancers. In contrast to superinduction of inflammatory genes via enhancers that harbor IRF sequences and bind STAT1, IFN-γ-mediated repression targeted enhancers with STAT sequences that bound STAT3. TLR4-activated IFN-γ-suppressed enhancers comprised two subsets distinguished by differential regulation of histone acetylation and recruitment of STAT3, CDK8 and cohesin, and were functionally inactivated by IFN-γ. These findings reveal that IFN-γ suppresses feedback inhibitory and metabolic components of the TLR response to achieve full M1 polarization, and provide insights into mechanisms by which IFN-γ selectively inhibits TLR4-induced transcription.
Project description:Complete polarization of macrophages towards an M1-like proinflammatory and antimicrobial state requires combined action of IFN-γ and LPS. Synergistic activation of canonical inflammatory NF-κB target genes by IFN-γ and LPS is well appreciated, but less is known about whether IFN-γ negatively regulates components of the LPS response, and how this affects polarization. A combined transcriptomic and epigenomic approach revealed that IFN-γ selectively abrogates LPS-induced feedback and select metabolic pathways by suppressing TLR4-mediated activation of gene enhancers. In contrast to superinduction of inflammatory genes via enhancers that harbor IRF sequences and bind STAT1, IFN-γ-mediated repression targeted enhancers with STAT sequences that bound STAT3. TLR4-activated IFN-γ-suppressed enhancers comprised two subsets distinguished by differential regulation of histone acetylation and recruitment of STAT3, CDK8 and cohesin, and were functionally inactivated by IFN-γ. These findings reveal that IFN-γ suppresses feedback inhibitory and metabolic components of the TLR response to achieve full M1 polarization, and provide insights into mechanisms by which IFN-γ selectively inhibits TLR4-induced transcription.
Project description:Complete polarization of macrophages towards an M1-like proinflammatory and antimicrobial state requires combined action of IFN-γ and LPS. Synergistic activation of canonical inflammatory NF-κB target genes by IFN-γ and LPS is well appreciated, but less is known about whether IFN-γ negatively regulates components of the LPS response, and how this affects polarization. A combined transcriptomic and epigenomic approach revealed that IFN-γ selectively abrogates LPS-induced feedback and select metabolic pathways by suppressing TLR4-mediated activation of gene enhancers. In contrast to superinduction of inflammatory genes via enhancers that harbor IRF sequences and bind STAT1, IFN-γ-mediated repression targeted enhancers with STAT sequences that bound STAT3. TLR4-activated IFN-γ-suppressed enhancers comprised two subsets distinguished by differential regulation of histone acetylation and recruitment of STAT3, CDK8 and cohesin, and were functionally inactivated by IFN-γ. These findings reveal that IFN-γ suppresses feedback inhibitory and metabolic components of the TLR response to achieve full M1 polarization, and provide insights into mechanisms by which IFN-γ selectively inhibits TLR4-induced transcription.