Epigenetics of Severe Systemic Inflammation

描述（由申请人提供）：严重全身性炎症（SSI）由败血症或非感染性因素引起的多器官功能障碍是一种死亡率和发病率高的疾病。SSI与先天免疫白细胞对toll样受体(TLR)-4依赖性信号的基因特异性重编程有关，TLR -4依赖性信号在表观遗传上抑制一组急性促炎基因的转录，同时激活其他产生抗炎介质和抗微生物肽的基因。这种基因重编程至少在两个方面很重要。它的存在表明先天免疫和适应性免疫受到抑制，其逆转与人类和动物SSI预后的改善相关。我们已经报道了表观遗传沉默特征需要toll样受体4 （TLR4）诱导NF-kappa B因子RelB，其破坏p65启动子结合，指导组蛋白H3K9被G9a二甲基化以提供异染色质蛋白1 （HP1）的结合位点，然后连接DNA CpG甲基化反应和染色质结构蛋白。这种依赖relb的过程改变了反应性常染色质的状态，产生沉默的兼性异染色质。我们研究的总体目标是确定染色质在常染色质和兼性异染色质状态之间转移的机制。本研究验证了G9a和RelB在SSI过程中通过直接结合G9a为兼性异染色质的组装和拆卸提供了一个纽带的假设，G9a与组蛋白和DNA修饰剂以及结构染色质蛋白如连接组蛋白H1和高迁移率组蛋白1 （HMGB1）蛋白结合。目的1将测试G9a和RelB之间的直接相互作用和反馈，以启动和逆转急性促炎基因TNFa和IL-1b近端启动子从活性常染色质到兼性异染色质的基因特异性变化。Aim 2将测试连接体组蛋白H1是否与HMGB1一起，通过重新定位核小体和维持TNFa和IL-1b启动子序列上的RelB和G9a结合来维持异染色质组装和转录沉默。目的3将使用人类外周血白细胞将基因特异性重编程范式扩展到人类SSI。我们的实验方法将采用遗传和生化分析。

DESCRIPTION (provided by applicant): Severe systemic inflammation (SSI) with multiorgan dysfunction from sepsis or non infectious agents is a disease with major mortality and morbidity. SSI is associated with gene-specific reprogramming of innate immunity leukocyte responses to Toll-like receptor (TLR)-4dependent signaling, which epigenetically represses transcription of a set of acute proinflammatory genes, while activating other sets of genes that generate anti- inflammatory mediators and anti-microbial peptides. This gene reprogramming is important in at least two ways. Its presence indicates repressed innate and adaptive immunity and its reversal correlates with improved outcomes in SSI in humans and animals. We have reported that the epigenetic silencing signature requires Toll-like receptor 4 (TLR4) induction of NF-kappa B factor RelB that disrupts p65 promoter binding, directs histone H3K9 di-methylation by G9a to provide a binding site of heterochromatin protein 1 (HP1), which then links to DNA CpG methylation responses and chromatin structural proteins. This RelB-dependent process alters the state of responsive euchromatin to produce silenced facultative heterochromatin. The general objective of our research is to define mechanisms that shift chromatin between the euchromatin and facultative heterochromatin states. This proposal tests the hypothesis that G9a and RelB provide a bond for both assembling and disassembling facultative heterochromatin during SSI by its ability to directly bind G9a, which couples to histone and DNA modifiers and structural chromatin proteins like linker histone H1 and high mobility group box 1 (HMGB1) proteins. Aim 1 will test for direct interaction and feedback between G9a and RelB to initiate and reverse gene-specific change from active euchromatin to facultative heterochromatin at the proximal promoters of acute proinflammatory genes TNFa and IL-1b. Aim 2 will test whether the linker histone H1, in concert with HMGB1, sustains heterochromatin assembly and transcription silencing by re-positioning nucleosomes and maintaining RelB and G9a binding at promoter sequences of TNFa and IL-1b. Aim 3 will use human peripheral blood leukocytes to extend the gene-specific reprogramming paradigm to human SSI. Our experimental approaches will employ genetic and biochemical analyses.] PUBLIC HEALTH RELEVANCE: Severe systemic inflammation (SSI) from sepsis or trauma has substantial public health impact through its high mortality and sustained morbidity. This translational research should define novel mechanisms responsible for the epigenetic basis for gene reprogramming in inflammation. From these results, novel therapeutic interventions or preventions may be designed to improve the poor outcomes associated with SSI.