NK Cell Differentiation from Stem Cells

描述(申请人提供)：自然杀伤(NK)细胞从原始的造血干细胞发展为功能性的抗肿瘤效应细胞，表达识别MHC I类配体的受体。除了杀伤免疫球蛋白样受体(KIR)家族外，NKG2A和LIR-1还识别MHC I类配体。我们的数据表明，尽管血液中循环的KIR-/NKG2A-NK细胞群不能被自身配体抑制，但它们不是自身反应，而是低反应和耐受。这些低反应细胞获得功能的机制首先依赖于NK细胞受体的获得，然后依赖于随后与其MHC I类配体的相互作用。自然杀伤细胞教育过程也被称为许可证发放、校准或武装/解除武装。受过同源配体训练的NK细胞对配体阴性的靶点表现出更高的功能，而未受过教育的NK细胞仍然反应迟钝。最重要的假设是，人类NK细胞的培养过程与NK细胞的发育是协调的，并进一步受到激活-炎症信号和抑制性受体连接的调节。我们认为，虽然NK细胞培养可以精确地调节先天免疫反应，但这一机制可能不是绝对的，它可以被激活-炎症信号逆转。尽管KIR和KIR配体之间的相互作用主导了临床文献，但血液中的KIR-NK细胞群体显示出强大的抗肿瘤功能，可能是因为它们是通过NKG2A或LIR-1培养出来的。在目前的资助期间，我们建立了IL-15和c-Myc上调之间的机械联系。IL-15已知能激活NK细胞。C-Myc直接与常规近端启动子上游1kb的KIR启动子结合，导致远端启动子转录。我们假设在NK细胞培养中有几个额外的因素发挥作用，包括Notch、间质、稳态和炎症激活信号(独立于特定的NK细胞受体)，最后是与抑制性受体的相互作用。我们的人脐血干细胞发育模型是理想的，因为它概括了NK细胞的发育，但有利于NK细胞受体阴性的低反应NK细胞。提出了三个具体目标：具体目标1：作为发育事件的NK细胞的承诺和全球功能的获得。具体目标2：NK细胞承诺后的NK细胞教育。具体目标3：获取KIR的机制。考虑到我们自己的工作表明NK细胞在造血细胞移植和癌症治疗中的作用，这些研究的意义是高度翻译上的兴趣。了解KIR转录的机制可能最终使我们能够特异性地操纵NK细胞。公共卫生相关性：项目自然杀伤(NK)细胞是一种循环中的白细胞，可以杀死癌细胞和病毒感染的目标。当这些先天免疫细胞从造血干细胞发展而来时，它们就会发展出杀伤目标和分泌细胞因子的能力。为了诱导自身耐受和避免对健康组织的损害，NK细胞通过与抑制性NK受体结合的“自身”MHC分子进行培养。此次R01更新的主要目的是了解NK细胞发育的各个阶段，包括NK细胞受体的获得和NK细胞功能的调节。对这些机制的透彻了解可能会使我们能够操纵NK细胞用于治疗癌症。

DESCRIPTION (provided by applicant): Natural killer (NK) cells develop from primitive hematopoetic stem cells into functional anti-tumor effector cells that express receptors recognizing MHC class I ligands. In addition to the killer immunoglobulin-like receptor (KIR) family, NKG2A and LIR-1 also recognize MHC class I ligands. Our data show that although the population of KIR-/NKG2A- NK cells circulating in blood cannot be inhibited by self ligands, they are not autoreactive, but instead are hyporesponsive and tolerant. The mechanism by which these hyporesponsive cells acquire function is dependent first on the acquisition of NK cell receptors and then on subsequent interactions with their MHC class I ligands. The process of NK cell education is also referred to as licensing, calibration or arming/disarming. NK cells that have been educated by exposure to cognate ligand exhibit higher function against ligand-negative targets, while uneducated NK cells remain hyporesponsive. The overarching hypothesis is that the process of human NK cell education is coordinated with NK cell development and is further modulated by activation-inflammatory signals and inhibitory receptor ligation. We propose that although NK cell education can precisely adjust the innate immune response, this mechanism may not be absolute and that it can be reversed by activation-inflammatory signals. Although interactions between KIR and KIR-ligand dominate the clinical literature, a population of KIR- NK cells in blood exhibit potent anti-tumor function, possibly because they have been educated through NKG2A or LIR-1. During the current funding, we established a mechanistic link between IL-15, known to activate NK cells, and the upregulation of c-Myc. C-Myc binds directly to a KIR promoter 1 Kb upstream of the conventional proximal promoter and leads to distal promoter transcription. We hypothesize that several additional factors play a role in NK cell education, including Notch, stromal, homeostatic and inflammatory activation signals (independent of specific NK cell receptors), and lastly, interaction with inhibitory receptors. Our developmental model with human cord blood stem cells is ideal because it recapitulates NK cell development but favors NK cell receptor negative hyporesponsive NK cells. Three specific aims are proposed: Specific Aim 1: NK cell commitment and acquisition of global function as a developmental event. Specific Aim 2: NK cell education after NK cell commitment. Specific Aim 3: Mechanisms of KIR acquisition. The significance of these studies is of high translational interest given our own work suggesting a role for NK cells in hematopoietic cell transplantation and as therapy for cancer. Understanding mechanisms of KIR transcription may ultimately allow us to manipulate NK cells with specificity. PUBLIC HEALTH RELEVANCE: PROJECT Natural killer (NK) cells are a type of circulating white blood cell which can kill cancer cells and virally infected targets. As these innate immune cells develop from hematopoietic stem cells they develop the ability to kill targets and secrete cytokines. In order to induce self tolerance and avoid damage to healthy tissues, NK cells are educated by "self" MHC molecules which bind inhibitory NK receptors. The main goal of this R01 renewal is to understand the stages of NK cell development, including the acquisition of NK cell receptors, and the regulation of NK cell function. A thorough understanding of these mechanisms may allow us to manipulate NK cells for therapeutic purposes to treat cancer.