Project description: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 major effector cells and antigen presenting cells of the innate immune system and classical activation of macrophage function requires interferon–γ (IFN-γ) pretreatment (priming) and TLR stimuli, which promotes inflammatory responses though high levels of pro-inflammatory cytokines and lower level of the anti-inflammatory cytokines, resulting in microbicidal and tumoricidal effect. However, the underlying molecular mechanism of IFN-γ priming remains elusive. In this study, we explored the effect of IFN-γ on macrophages at miRNA level and discovered that miR-3473b, which was down-regulated after IFN-γ priming, could attenuate the priming effect of IFN-γ. Molecular study revealed that miR-3473b promoted Akt/GSK3 signaling and IL-10 production through directly targeting PTEN to suppress inflammatory response and tumor-suppressing capability of macrophages. In summary, our data demonstrate that IFN-γ beef up macrophage inflammatory response and tumor suppressing capacity by limiting miR-3473b-mediated PTEN suppression. Our work identified an IFN-γ/miR-3473b/Akt axis in the regulation of macrophage function and activation. the assay was performed with 5 μg total RNA samples from both normal BMM (labeled by Cy3) and BMM primed by IFN-γ (100U/ml) for 4 h(labeled by Cy5), normal BMM serves as control.
Project description:Mechanisms by which IFN-γ activates genes to promote macrophage activation are well studied, but little is known about mechanisms and functions of IFN-γ-mediated gene repression. We used an integrated transcriptomic and epigenomic approach to analyze chromatin accessibility, histone modifications, transcription factor binding, and gene expression in IFN-γ-primed human macrophages. IFN-γ suppressed basal expression of genes corresponding to an ‘M2’-like homeostatic/reparative phenotype. IFN-γ repressed genes by suppressing the function of enhancers enriched for binding by transcription factor MAF. Mechanistically, IFN-γ ‘disassembled’ a subset of enhancers by inducing coordinate suppression of binding by MAF, lineage-determining transcription factors, and chromatin accessibility. Genes associated with MAF-binding disassembled enhancers were suppressed in rheumatoid arthritis macrophages, revealing a disease-associated ‘negative IFN-γ signature’. These results identify enhancer inactivation and disassembly as a mechanism of IFN-γ-mediated gene repression, and MAF as a regulator of the macrophage enhancer landscape that is suppressed by IFN-γ to augment macrophage activation.
Project description:Mechanisms by which IFN-γ activates genes to promote macrophage activation are well studied, but little is known about mechanisms and functions of IFN-γ-mediated gene repression. We used an integrated transcriptomic and epigenomic approach to analyze chromatin accessibility, histone modifications, transcription factor binding, and gene expression in IFN-γ-primed human macrophages. IFN-γ suppressed basal expression of genes corresponding to an ‘M2’-like homeostatic/reparative phenotype. IFN-γ repressed genes by suppressing the function of enhancers enriched for binding by transcription factor MAF. Mechanistically, IFN-γ ‘disassembled’ a subset of enhancers by inducing coordinate suppression of binding by MAF, lineage-determining transcription factors, and chromatin accessibility. Genes associated with MAF-binding disassembled enhancers were suppressed in rheumatoid arthritis macrophages, revealing a disease-associated ‘negative IFN-γ signature’. These results identify enhancer inactivation and disassembly as a mechanism of IFN-γ-mediated gene repression, and MAF as a regulator of the macrophage enhancer landscape that is suppressed by IFN-γ to augment macrophage activation.
Project description:Mechanisms by which IFN-γ activates genes to promote macrophage activation are well studied, but little is known about mechanisms and functions of IFN-γ-mediated gene repression. We used an integrated transcriptomic and epigenomic approach to analyze chromatin accessibility, histone modifications, transcription factor binding, and gene expression in IFN-γ-primed human macrophages. IFN-γ suppressed basal expression of genes corresponding to an ‘M2’-like homeostatic/reparative phenotype. IFN-γ repressed genes by suppressing the function of enhancers enriched for binding by transcription factor MAF. Mechanistically, IFN-γ ‘disassembled’ a subset of enhancers by inducing coordinate suppression of binding by MAF, lineage-determining transcription factors, and chromatin accessibility. Genes associated with MAF-binding disassembled enhancers were suppressed in rheumatoid arthritis macrophages, revealing a disease-associated ‘negative IFN-γ signature’. These results identify enhancer inactivation and disassembly as a mechanism of IFN-γ-mediated gene repression, and MAF as a regulator of the macrophage enhancer landscape that is suppressed by IFN-γ to augment macrophage activation.
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:Inborn errors of human IFN-γ immunity underlie mycobacterial diseases, whereas inborn errors of IFN-/ immunity underlie viral diseases. Both types of IFNs induce the transcription factor IRF1. We describe two unrelated children with inherited complete IRF1 deficiency and early-onset, multiple, life-threatening diseases caused by weakly virulent mycobacteria. These children have no history of severe viral disease, despite exposure to many viruses, including SARS-CoV-2, which is life-threatening in individuals with impaired IFN-/ immunity. The IRF1-dependent cellular responses to IFN-γ are, both quantitatively and qualitatively, much greater than those to IFN-/ in vitro. Monocyte- and iPSC-derived macrophages from the two patients show no upregulation of at least 20% of the target genes normally induced by IFN-γ. By contrast, cell-intrinsic IFN-/ immunity to diverse viruses, including SARS-CoV-2, is intact. Human IRF1 is, thus, largely redundant for antiviral IFN-/ immunity. By contrast, human IRF1 is essential for IFN-γ immunity to mycobacteria in myeloid cells.
Project description:G-protein coupled receptors (GPCRs) have diverse roles in physiological processes, including immunity. Gs-coupled GPCRs increase while Gi-coupled ones decrease intracellular cAMP. Previous studies suggest that, in epithelial cells, Gs-coupled GPCRs enhance whereas Gi-coupled GPCRs suppress pro-inflammatory immune responses. In order to examine the issue, we chose beta2 adrenergic receptor and GPR40 as representatives of Gs- and Gi- coupled GPCRs, respectively, and examined their effects on TNF-alpha and IFN-gamma-(TNF-alpha + IFN-gamma) induced gene expression by HaCaT. We used microarrays to detail the global changes of gene expression induced by a beta2 adrenergic receptor agonist terbutaline or GPR40 agonist GW9508 pre-treatment in TNF-alpha + IFN-gamma - stimulated HaCaT cells. HaCaT cells were pre-treated with terbutaline or GW9508, TNF-alpha + IFN-gamma were then added, and cultured for another 24 h. Cells were then used for RNA extraction and hybridization on Affymetrix microarrays. We sought to clarify changes in gene expression after 1) TNF-alpha + IFN-gamma, 2) TNF-alpha + IFN-gamma + terbutaline, and 3) TNF-alpha + IFN-gamma + GW9508 treatment. To this end, we set 4 groups of samples; 1) unstimulated group, 2) TNF-alpha + IFN-gamma-stimulated group, 3) TNF-alpha + IFN-gamma + terbutaline-stimulated group, and 4) TNF-alpha + IFN-gamma + GW9508-stimulated group. In each group, HaCaT cells were stimulated in triplicate wells (n=3).