The role of ascorbate in myelopoiesis and infection

项目总结： 我们已经开发出方法来描述造血干细胞(HSCs)和其他稀有细胞的代谢组 从组织中提纯的类型。每种造血细胞类型都有不同的代谢物特性。大多数代谢物 在特定的细胞类型中被丰富或被耗尽，这表明它们可能具有新的细胞类型的特定作用。肝星状细胞 而小鼠和人骨髓中的多能祖细胞(MPP)含有高水平的抗坏血酸(维生素 C)，促进HSC功能抑制因子TET2的活性。造血特异性 抗坏血酸缺乏可促进HSC功能、骨髓生成和炎性髓系细胞的生成。 并导致早期死亡。抗坏血酸缺乏在人类群体中很常见，因为在早期灵长类动物中 进化过程中，我们失去了合成抗坏血酸的能力。健康人缺乏抗坏血酸与 不明原因的死亡风险增加。造血功能缺失的TET2突变也有 在人类中很常见，并推动突变血细胞的克隆性增殖，称为克隆性造血。TET2- 血细胞不足可能会增加死亡的风险。此应用程序的目标是 了解抗坏血酸在骨髓生成调节中的作用。我们的中心假设是抗坏血酸 抑制骨髓生成，抗坏血酸缺乏会增加骨髓生成和炎症 疟原虫感染。为了验证这一假设，我们将使用基因工程抗坏血酸缺陷小鼠，以 模拟人类的情况，和TET2基因缺陷的小鼠。在目标1中，我们将测试抗坏血酸是否抑制 通过作用于造血干细胞或限制髓系祖细胞而产生炎性髓系细胞，如果这是 由TET2介导。在目标2中，我们将确定抗坏血酸缺乏或TET2缺乏对 疟疾小鼠模型中对疟原虫感染的造血细胞反应。在目标3中，我们将调查 抗坏血酸缺乏和TET2缺乏促进小鼠发病率和死亡率的机制 疟原虫感染。这些实验可能会对公众健康产生重大影响。他们可以辨认出 生理状况，如感染，其中存在抗坏血酸缺乏和TET2缺乏 克隆性造血对机体有害。他们还可以确定异常行为的机制 骨髓生成有助于疟疾的发病，疟疾困扰着全世界2亿多人。

PROJECT SUMMARY: We have developed methods to profile the metabolome of hematopoietic stem cells (HSCs) and other rare cell types purified from tissues. Each hematopoietic cell type had a distinct metabolite identity. Most metabolites were enriched or depleted in specific cell types, suggesting they may have novel cell-type specific roles. HSCs and multipotent progenitors (MPPs) in mouse and human bone marrow had high levels of ascorbate (Vitamin C), which promoted the activity of the enzyme TET2, a suppressor of HSC function. Hematopoietic-specific ascorbate deficiency promoted HSC function, myelopoiesis and the generation of inflammatory myeloid cells, and caused early lethality. Ascorbate deficiency is common in the human population because in early primate evolution we lost the ability to synthesize ascorbate. Ascorbate deficiency in healthy people is associated with increased risk of mortality for unknown reasons. Hematopoietic TET2 loss of function mutations are also common in humans, and drive a clonal expansion of mutant blood cells termed clonal hematopoiesis. TET2- deficient blood cells may contribute to an increased risk of mortality. This application’s objective is to understand the role of ascorbate in the regulation of myelopoiesis. Our central hypothesis is that ascorbate suppresses myelopoiesis, and that ascorbate deficiency increases myelopoiesis and inflammation after plasmodium infection. To test this hypothesis, we will use genetically engineered ascorbate deficient mice, to mimic the human condition, and Tet2-deficient mice. In Aim 1 we will test if ascorbate suppresses the generation of inflammatory myeloid cells by acting on HSCs or restricted myeloid progenitors, and if this is mediated by Tet2. In Aim 2 we will determine the effects of ascorbate deficiency or Tet2 deficiency on the myelopoietic response to Plasmodium infection in a mouse model of malaria. In Aim 3 we will investigate the mechanisms by which ascorbate deficiency and Tet2 deficiency promote morbidity and mortality in Plasmodium infection. These experiments may have significant public health implications. They could identify physiological situations, such as infection, in which the presence of ascorbate deficiency and Tet2-deficient clonal hematopoiesis are deleterious to the organism. They may also identify mechanisms by which aberrant myelopoiesis contributes to the pathogenesis of malaria which afflicts more than 200 million people worldwide.