Epigenetics of Severe Systemic Inflammation

描述(申请人提供)：严重全身炎症(SSI)合并多器官功能障碍，由脓毒症或非感染性因素引起，是一种死亡率和发病率都很高的疾病。SSI与天然免疫白细胞对Toll样受体(TLR)-4依赖的信号反应的基因特异性重编程有关，TLR-4依赖的信号在表观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菌肽的基因。这种基因重新编程至少在两个方面很重要。它的存在表明先天免疫和获得性免疫受到抑制，其逆转与人类和动物SSI结果的改善相关。我们已经报道，表观遗传沉默信号需要Toll样受体4(TLR4)诱导NF-kappa B因子RelB破坏p65启动子的结合，指导组蛋白H3K9由G9a二甲基化提供异染色质蛋白1(HP1)的结合部位，然后连接到DNA CpG甲基化反应和染色质结构蛋白。这种依赖于RelB的过程改变了反应常染色质的状态，从而产生沉默的兼性异染色质。我们研究的总体目标是确定在常染色质和兼性异染色质状态之间转移染色质的机制。这一建议检验了这样的假设，即G9a和RelB通过直接结合G9a的能力，为SSI过程中兼性异染色质的组装和拆解提供了一个键。G9a与组蛋白和DNA修饰物以及结构染色质蛋白如连接物组蛋白H1和高迁移率族蛋白1(HMGB1)偶联。目的1将测试G9a和RelB之间的直接相互作用和反馈，以启动和逆转急性致炎基因TNFa和IL-1b近端启动子的基因特异性变化，从活性常染色质到兼性异染色质。目的2将通过重新定位核小体并保持RelB和G9a与TNFa和IL-1b启动子序列的结合，来测试连接子H1HMGB1是否通过重新定位核小体来维持异染色质组装和转录沉默。AIM 3将使用人类外周血白细胞将基因特异性重新编程范例扩展到人类SSI。我们的实验方法将使用遗传和生化分析。] 公共卫生相关性：脓毒症或创伤引起的严重全身炎症(SSI)因其高死亡率和持续的发病率而对公共卫生造成重大影响。这项转译研究应该确定炎症中基因重编程的表观遗传学基础的新机制。根据这些结果，可以设计新的治疗干预或预防措施来改善SSI相关的不良结局。

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.