The genetic basis for differential macrophage activation
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ABSTRACT: Differential macrophage activation mediate genetic differences to a variety of inflammatory pathologies. We wanted to elucidate the transcriptional and regulatory programs regulating differential macrophage activation in genetically diverse mouse strains. Bone marrow-derived macrophages (BMDMs) from AJ and C57BL/6j mice were left unstimulated, stimulated with IFN/TNF, or IL-4, or CpG, or LPS or IFN/TNF and infected with a type II (Pru A7) strain of Toxoplasma gondii, or infected with Pru A7 and gene expression analyzed 18 hrs later.
Project description:The Toxoplasma type I ROP16 kinase directly activates the host STAT3 and STAT6 transcription factors and regulates the expression of many host genes. However, many of genes lack known STAT3/6 transcription factor binding sites in their promoter regions. We wanted to understand what fraction of host genes that are modulated by ROP16 were dependent on the STAT3 and STAT6 signaling pathways. Bone marrow-derived macrophages (BMMs) from mLys-Mcre Stat3fl/fl mice were infected with type II (Pru A7), type II +ROP16 I, type II Δgra15, or type II Δgra15 + ROP16I and gene expression was analyzed 18 hrs after infection. This data set was generated side by side with infections performed in B6 BMDMs, the gene expression results for that experiment were previoiusly submitted under the GEO accession number GSE29404. In addition, gene expression of wild type B6 and Stat6-/- BMDMs were infected with the II+ROP16I strain.
Project description:Alternative splicing and mRNA editing are known to contribute to transcriptome diversity. Although alternative splicing is pervasive and known to contribute to a variety of pathologies, including cancer, the genetic context for individual differences in isoform usage is still evolving. Similarly, although mRNA editing is ubiquitous and associated with important biological processes such as intracellular viral replication and cancer development, individual variations in and the genetic transmissibility of mRNA editing are equivocal. Here, we have used linkage analysis to show that both mRNA editing and alternative splicing are regulated by the macrophage genetic background and environmental cues. We show that distinct loci, potentially harboring variable splice factors, regulate the splicing of multiple transcripts. Additionally, we show that individual genetic variability at the Apobec1 locus results in differential rates of C-to-U(T) editing in murine macrophages; with mouse strains expressing mostly a truncated isoform of Apobec1 exhibiting lower rates of editing. As a proof of concept, we have used linkage analysis to identify 36 high confidence novel edited sites. These results provide a novel and complementary method that can be used to identify C-to-U editing sites in individuals segregating at specific loci and show that, beyond individual DNA sequence and structural changes, differential isoform usage and mRNA editing can contribute to intra-species genomic and phenotypic diversity. Bone marrow derived macrophages (BMDM) from female AxB/BxA mice were left unstimulated or stimulated with IFNG/TNF, or CpG for 18 hrs or infected with infected with type II (Pru A7) for 8 hrs. The transcriptional response was then measured using the illumina RNA-seq protocol on an illumuna HiSeq 2000.
Project description:Anti-TNF therapies are a core anti-inflammatory approach for chronic diseases such as rheumatoid arthritis and Crohn’s Disease. Previously, we and others found that TNF blocks the emergence and function of alternatively-activated or M2 macrophages involved in wound healing and tissue-reparative functions. Conceivably, anti-TNF drugs could mediate their protective effects in part by an altered balanced of macrophage activity. To understand the mechanistic basis of how TNF regulates tissue-reparative macrophages we used RNAseq, scRNAseq, ATACseq, time-resolved phospho-proteomics, gene-specific approaches, metabolic analysis and signaling pathway deconvolution. Our findings reveal that TNF controls tissue-reparative macrophage gene expression in a highly gene-specific way dependent on JNK signaling. We uncover principles of the selectively inhibition by TNF via the type 1 TNF receptor on specific populations of alternative activated macrophages.
Project description:Analysis of gene expression between WT and iNOS defecient M1 macrophage RNA microarray was performed using RNA isolated from M1 polarized macrophages from WT and iNOS deficient mice stimulated with LPS/IFNγ for 6 hours. Total RNA was extracted using a RNeasy plus kit (QIAGEN, Valencia, CA), and the array was performed on an Illumina MouseRef-8 v2.0 expression beadchip (Illumina, USA) by the Genomics Core Facility at the Mount Sinai School of Medicine.
Project description:The bacterial product lipopolysaccharide (LPS) stimulates nuclear factor kB (NF-kB) signaling, which results in the production of proinflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha), as part of the immune response. NF-kB target genes also include those encoding proteins that inhibit NF-kB signaling through negative feedback loops. By simultaneously studying the dynamics of the nuclear translocation of the NF-kB subunit RelA and the activity of a Tnf-driven reporter in a mouse macrophage cell line, Sung et al. found that the gene encoding RelA was also a target of NF-kB. Synthesis of RelA occurred only at higher concentrations of LPS and constituted a positive feedback loop that dominated over existing negative feedback mechanisms. Genes expressed in response to a high concentration of LPS were enriched for those involved in innate immune responses. Together, these data suggest that the RelA-dependent positive feedback loop enables macrophages to mount an effective immune only above a critical concentration of LPS. Bone-marrow-derived macrophage (BMDM) cells were stimulated with zero, low, and high concentration of LPS separately for 4hrs. Two replicates for each condition.
Project description:Toxoplasma strains are known to inhibit the expression of several interferon-gamma induced genes, and a type II strain was shown to dysregulate genome-wide responses to interferon-gamma in human fibroblasts (Kim et al., 2007, J Immunol.). In this study we aimed to determine the effect of infection with three clonal lineages of Toxoplasma, type I, II, and III strains on genome-wide interferon-gamma induced transcription in murine macrophages. We also assessed the effect of the two main Toxoplasma modulators of mouse macrophage transcription, ROP16 and GRA15 (Jensen et al., 2011, Cell Host Microbe). We used Affymetrix microarrays to analyze host cell transcription after Toxoplasma infection and interferon-gamma stimulation. RAW264.7 murine macrophages were left uninfected or infected with type I (RH), type I ?rop16 (RH ?rop16), type II (Pru), type II ?gra15 (Pru ?gra15), or type II (CEP) parasites at an MOI ~5 for 18 hours and subsequently stimulated with murine IFN-? for six hours. Plaque assays were done to assess parasite viability. Total RNA was isolated and hybridized to Affymetrix Mouse 430A 2.0 gene chips.
Project description:This study shows that in the absence of Atf3, primary mouse macrophages display significantly greater basal and PRR-inducible IFNβ expression. This regulation appears to be directly on the level of Ifnb1 transcription mediated by ATF3 binding proximal to the Ifnb1 promoter under basal condition. The ATF3 expression was demonstrated to be type I IFN-inducible in both human and mouse immune cells. A subset of 36 genes downstream of IFNAR signalling were modulated in an ATF3-dependent manner.The regulation of IFN responses by ATF3 had significant relevance on in vitro viral infection. Together these findings demonstrate that ATF3 is an important regulatory handbrake that limits the magnitude of IFN responses on multiple levels; basal Ifnb1 expression; PRR-inducible IFNβ; and the expression of specific ISGs. 12 samples
Project description:Interferon (IFN)γ and interleukin (IL)-4 are central regulators of T helper 1 (Th1) and T helper 2 (Th2) immune responses, respectively. Both cytokines have a major impact on macrophage phenotypes: IFNγ–priming and subsequent TLR4 activation induces so called classically activated macrophages that are characterized by pronounced pro-inflammatory responses, whereas IL-4–treated macrophages, commonly called alternatively activated, are known to develop enhanced capacity for endocytosis, antigen presentation, and tissue repair and are generally considered anti-inflammatory. Considering IL-4 as priming rather than activating stimulus, we now compared the TLR4–dependent global gene activation program in IFNγ– versus IL-4–pretreated mouse macrophages, which has rarely been studied so far. Although both cytokines frequently induced opposing effects on gene transcription, the subsequent activation of bone marrow-derived macrophages by lipopolysaccharide (LPS) produced a strong, priming dependent pro-inflammatory response in both macrophage types. For example, the production of key pro-inflammatory cytokines IL-6 and IL-12 was significantly higher in IL-4– versus IFNγ–primed macrophages and several cytokine genes, including Il19, Ccl17, Ccl22, Ccl24 and Cxcl5, were preferentially induced in alternatively primed and LPS activated mouse macrophages. In a subset of genes, including IL12a, IFNγ priming was actually found to suppress LPS–induced gene expression in a Stat1–dependent manner. Our data suggest that IL-4–priming is not per se anti-inflammatory but generates a macrophage that is “tissue protective” but still capable of mounting a strong inflammatory response after TLR4–dependent activation. Keywords: Gene expression profiling Gene expression was investigated in mouse bone marrow-derived macrophages (BMM). On day 7, BMM were stimulated with either IL-4 or IFNγ overnight (18h in total). LPS treatment was performed in primed and unprimed macrophages 4 h prior to harvesting. At least three independent experiments were performed for each condition.
Project description:The specific binding of transcription factors to cognate sequence elements is thought to be critical for the generation of specific gene expression programs. The transcription factors nuclear factor kB (NF-kB) and the interferon (IFN) regulatory factors (IRFs) bind to the kB site and the interferon response element (IRE), respectively, of target genes, and they are activated in macrophages after exposure to pathogens. However, how these factors produce pathogen-specific inflammatory and immune responses remains poorly understood. Combining top-down and bottom-up systems biology approaches, we have identified the NF-kB p50 homodimer (p50:p50) as a regulator of IRF responses. First, unbiased genome-wide expression analysis revealed that p50 repressed a subset of IFN-inducible genes through a previously uncharacterized subclass of guanine-rich IRE (G-IRE) sequences, which was substantiated by biochemical and structural analyses. Second, mathematical modeling predicted that p50:p50 might enforce the stimulus-specificity of composite promoters. Indeed, the production of the antiviral regulator IFN-b was rendered stimulus-specific by the binding of p50:p50 to the G-IRE–containing IFNb enhancer to suppress cytotoxic IFN signaling. Specifically, a deficiency in p50 resulted in the inappropriate production of IFN-b in response to bacterial DNA sensed by Toll-like receptor 9. This role for NF-kB p50 in enforcing the specificity of the cellular response to pathogens by binding to a previously uncharacterized subset of IRE sequences alters our understanding of how the NF-kB and IRF signaling systems cooperate to regulate antimicrobial immunity. [BMDM]: Total RNA extracted from wt, p50-/- or ifnar-/- bone marrow derived macrophages (BMDMs) were subjected to stimulation with LPS, CpG or IFNb [MEF]: Total RNA extracted from wt or p50KO primary mouse embryonic fibroblasts were subjected to stimulation with LPS or IFNb