NK Cell Differentiation from Stem Cells

描述（由申请人提供）：自然杀伤（NK）细胞从原始造血干细胞发育成功能性抗肿瘤效应细胞，表达识别MHC I类配体的受体。除了杀手免疫球蛋白样受体（KIR）家族外，NKG2A和LIR-1也识别MHC I类配体。我们的数据表明，虽然血液中循环的KIR-/NKG2A- NK细胞群不能被自身配体抑制，但它们不是自身反应性的，而是低反应性和耐受性的。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。NK细胞教育的过程也被称为许可，校准或武装/解除武装。暴露于同源配体的NK细胞对配体阴性靶标表现出更高的功能，而未受教育的NK细胞仍然反应迟钝。总体假设是人类NK细胞教育过程与NK细胞发育协调，并通过激活-炎症信号和抑制性受体连接进一步调节。我们提出，尽管NK细胞教育可以精确地调节先天免疫反应，但这种机制可能不是绝对的，它可以通过激活炎症信号逆转。虽然KIR和KIR-配体之间的相互作用在临床文献中占主导地位，但血液中的KIR- NK细胞群体表现出强大的抗肿瘤功能，可能是因为它们通过NKG2A或LIR-1接受了教育。在目前的资助中，我们建立了IL-15（已知可以激活NK细胞）与c-Myc上调之间的机制联系。C-Myc直接与传统近端启动子上游1kb的KIR启动子结合，并导致远端启动子转录。我们假设有几个额外的因素在NK细胞教育中起作用，包括Notch、基质、稳态和炎症激活信号（独立于特定NK细胞受体），以及最后与抑制受体的相互作用。我们的人类脐带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:NK细胞承诺和获得全球功能作为一个发展事件。特异性目标2:NK细胞承诺后的NK细胞教育。具体目标3:KIR获取的机制。鉴于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，这些研究的意义具有很高的翻译兴趣。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。自然杀伤（NK）细胞是一种循环白细胞，可以杀死癌细胞和病毒感染的目标。随着这些先天免疫细胞从造血干细胞发育而来，它们发展出杀死靶标和分泌细胞因子的能力。为了诱导自身耐受，避免对健康组织的损伤，NK细胞被结合抑制性NK受体的“自身”MHC分子所教育。R01更新的主要目的是了解NK细胞发育的阶段，包括NK细胞受体的获取和NK细胞功能的调节。对这些机制的透彻理解可能使我们能够操纵NK细胞用于治疗癌症的目的。

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.