The mechanisms of bacterial microbiome regulation of hematopoiesis

项目摘要 两周或两周以上的抗生素疗程会导致多达15%的患者出现中性粒细胞减少和其他血细胞减少， 会导致医疗费用和死亡率的增加。鉴于2.69亿份抗生素处方， 这些不良血液学事件及其下游 其后果是一个主要的临床问题。因此，本研究的总体目标是了解 微生物群促进正常造血的机制。 我们和其他人已经表明，微生物组及其副产物是维持正常的 在动物模型中，例如在给予抗生素后， 导致血细胞减少。本实验室建立了一种小鼠骨髓抑制模型， 表明细菌微生物组介导的造血是Stat1依赖性的。我们新的初步数据 表明微生物组通过I型干扰素（IFN）促进Stat1信号传导。但具体 微生物群促进稳态造血的分子机制仍然很差 明白最近的一项研究表明，无菌小鼠的造血功能， 类似于经抗肿瘤治疗的小鼠的异常，可以通过口服施用NOD1配体（NOD1L）来挽救。 我们的初步数据表明，细菌衍生的分子，如NOD1L和脱氨基酪氨酸（DAT）， 一种微生物代谢物，可以被骨髓识别以维持正常的血液生成。这 一项提案将检验微生物副产物利用免疫相关信号通路的假设， Stat1和Nod1调节稳态造血。 为了验证这一假设，我们首先将验证NOD1L和DAT作为新的治疗药物， 嗜中性粒细胞减少症。接下来，我们将比较在代谢组学的差异， 使用液相色谱和质谱法对经抗血小板治疗的野生型小鼠及其非血小板减少的对应小鼠进行了研究。 光谱法来鉴定维持正常造血的其他微生物线索。虽然这些研究将确定 支持稳态造血的细菌副产物，哪些细胞类型受到这些信号的影响 仍然未知。例如，已知NOD1L诱导间充质基质细胞中的细胞因子产生， 造血干细胞是骨髓微环境的重要组成部分，而干扰素可诱导造血干细胞分化。 因此，我们还将鉴定受NOD1L和DAT给药影响的细胞类型，以及 控制粒细胞生成的机制。最后，我们将定义微生物组与 通过分析造血治疗患者的细菌和代谢组学组成， 伴有和不伴有中性粒细胞减少症。这些研究将阐明微生物组调节的机制， 并可能发现新的治疗方法来挽救由长期抗生素诱导的中性粒细胞减少症 治疗

Project Summary Antibiotic courses of two or more weeks cause neutropenia and other cytopenias in up to 15% of patients, which can lead to increased medical costs and mortality. Given that 269 million prescriptions of antibiotics were prescribed to patients in the United States in 2015, these adverse hematological events and their downstream consequences represent a major clinical problem. Thus, the overarching goal of this study is to understand the mechanisms by which the microbiota promote normal hematopoiesis. We and others have shown that the microbiome and its byproducts are necessary for maintaining normal hematopoiesis and that depletion of the microbiota in animal models, such as after antibiotic administration, causes cytopenias. Our lab has established a mouse model of antibiotic-induced bone marrow suppression that demonstrated that bacterial microbiome-mediated hematopoiesis is Stat1-dependent. Our new preliminary data indicate that the microbiome promotes Stat1 signaling via type I interferons (IFN). However, the specific molecular mechanisms by which the microbiome contributes to steady-state hematopoiesis remain poorly understood. A recent study demonstrated that hematopoiesis in germ-free mice, which display hematopoietic abnormalities similar to antibiotic-treated mice, can be rescued by oral administration of NOD1 ligand (NOD1L). Our preliminary data suggest that bacterially-derived molecules such as NOD1L and desaminotyrosine (DAT), a microbial metabolite, may be recognized by the bone marrow to maintain normal blood production. This proposal will test the hypothesis that microbial byproducts utilize immune-related signaling pathways such as Stat1 and Nod1 to regulate steady-state hematopoiesis. In order to test this hypothesis, we first will validate NOD1L and DAT as novel therapeutic agents for antibiotic-mediated neutropenia. Next, we will compare differences in the metabolomic profiles of neutropenic antibiotic-treated wild-type mice and their non-neutropenic counterparts using liquid chromatography and mass spectrometry to identify other microbial cues that maintain normal hematopoiesis. While these studies will identify the bacterial byproducts that support steady-state hematopoiesis, which cell types are affected by these signals remains unknown. For instance, NOD1L is known to induce cytokine production in mesenchymal stromal cells, an important component of the bone marrow microenvironment, while IFNs can induce differentiation in HSCs. Therefore, we also will identify the cell types influenced by administration of NOD1L and DAT, as well as the mechanisms controlling granulopoiesis. Finally, we will define the link between the microbiome and hematopoiesis in patients by analyzing the bacterial and metabolomic compositions of antibiotic-treated patients with and without neutropenia. These studies will elucidate the mechanisms by which the microbiome regulates hematopoiesis and may identify novel therapeutics to rescue neutropenia induced by long-term antibiotic treatment.