Cellular and molecular mechanisms of target tissue resistance for mitigating GVHD severity

摘要： 异基因造血干细胞移植是治疗许多疾病的潜在疗法 恶性疾病的适用性因其最新技术的发展而受到阻碍 严重并发症，移植物抗宿主病(GVHD)。GVHD是由损伤引起的 由多种免疫细胞和炎性细胞因子引起的宿主上皮细胞靶点。 虽然在理解各种免疫的复杂作用方面取得了重大进展 细胞在引起移植物抗宿主病中的作用，对靶组织本身在其中所起的作用知之甚少。 控制疾病的严重程度。具体地说，宿主肠道上皮细胞(IEC)的诱导 同种异体反应性供者T细胞和炎性细胞因子诱导的胃肠道细胞凋亡 (GI)GVHD；然而宿主IEC对同种免疫T细胞介导的内在抵抗机制 损害，对这些抗性机制至关重要的表观遗传机制及其 组织驻留的微生物群产生的代谢物的调节从未被探索过。国际电工委员会 动态平衡和抵抗力取决于代谢能量之间的复杂相互作用 底物(如短链脂肪酸和氨基酸代谢物)及其调节 转录和表观遗传的染色质修饰，如组蛋白乙酰化。我们有 证明了全身组蛋白脱乙酰酶对表观遗传的调节 抑制物(HDACi)调节实验性GVHD并成功地将这一概念转化为 预防临床移植物抗宿主病的人体试验的原则证明。生成的初步数据 证明微生物代谢产物的底物发生了显著变化 例如必需短链脂肪酸(SCFA)和氨基酸代谢物，特别是在 胃肠道(IECS)中丁酸和色氨酸代谢产物吲哚-3-乙醛(I-3-A)水平 异基因骨髓移植后。初步数据还表明：(A)丁酸盐，一种已知的HDACi，可以增强 组蛋白乙酰化，调节IECS抗损伤和调节GVHD(B)的表达 芳香烃受体(AhR)(色氨酸代谢物吲哚-3-乙醛的传感器) 减轻GVHD的严重程度。但感知的途径和潜在的机制 丁酸盐和色氨酸代谢产物吲哚-3-乙醛在GVHD中的作用仍然存在 未知。因此，在这项提议中，我们将在这些令人兴奋和新颖的初步基础上 观察并将微生物区系、代谢组学、组织学的不同领域结合在一起 生物能量学和表观遗传学，以探索微生物代谢物和它们的 减少GI GVHD对IECS表观基因组改变的影响。具体地说，我们将测试 内源性肠道调节靶组织(IEC)抵抗的中心前提 微生物代谢物丁酸盐和色氨酸代谢物吲哚-3-乙醛，改变 乙酰化依赖的IECS表观基因组，负调控GI GVHD。

ABSTRACT: Allogeneic hematopoietic stem cell transplantation is potentially curative therapy for many malignant diseases whose applicability has been impeded by the development of its most serious complication, graft-versus-host disease (GVHD). GVHD results from the damage caused to the host epithelial cell targets by the many immune cells and inflammatory cytokines. While significant progress is being made in understanding the complex role of various immune cells in causing GVHD, little is known about the role played by the target tissues themselves in regulating the severity of disease. Specifically, induction of host intestinal epithelial cell (IEC) apoptosis by the alloreactive donor T cells and inflammatory cytokines causes gastrointestinal (GI) GVHD; however host IEC intrinsic resistance mechanisms to allo-immune T-cell mediated damage, the epigenetic mechanisms that are critical for these resistance mechanisms and its regulation by the tissue resident microflora generated metabolites has never been explored. IEC homeostasis and resistance depends on complex interactions between the metabolic energy substrates (such as short chain fatty acids and amino acid metabolites) and the regulation of transcription and epigenetic chromatin modifications such as histone acetylation. We have demonstrated that epigenetic regulation by systemic administration of histone deacetylase inhibitors (HDACi) regulates experimental GVHD and successfully translated this concept into a proof of principle human trial for prevention of clinical GVHD. Preliminary data generated demonstrate significant alterations in substrates that are derived from microbial metabolites such as essential short chain fatty acids (SCFA) and amino acids metabolites, specifically in butyrate and tryptophan metabolite indole-3-acetaldehyde (I-3-A) levels, in the GI tract (IECs) after allogeneic BMT. Preliminary data also show that (a) butyrate, a known HDACi, enhances histone acetylation, modulates IECs resistance to damage and regulates GVHD (b) expression of aryl hydrocarbon receptor (AhR) (a sensor of tryptophan metabolite indole-3-acetaldehyde) mitigates GVHD severity. But the pathways of sensing and the mechanisms underlying the butyrate and tryptophan metabolite indole-3-acetaldehyde -mediated effects in GVHD remain unknown. Therefore, in this proposal, we will build on these exciting and novel preliminary observations and bring together the diverse fields of microbiota, metabolomics, tissue bioenergetics and epigenetics, to explore the interplay between microbial metabolites and their effects on epigenomic alterations of the IECs in reducing GI GVHD. Specifically, we will test the central premise that regulation of target tissue (IEC) resistance by the endogenous intestinal microbial metabolites butyrate and tryptophan metabolite indole-3-acetaldehyde, alter the acetylation dependent epigenome of IECs and negatively regulates GI GVHD.