NK cell exhaustion in metastatic melanoma

项目摘要 NK细胞是对肿瘤发生和病毒感染的初始免疫应答的关键参与者， 通过诱导细胞因子和发挥细胞毒活性来快速响应。动态 正信号和负信号的平衡调节NK细胞靶细胞识别和溶解， 各种激活和抑制受体的接合。然而，随着癌症的发展， 不断积累的证据表明NK细胞功能逐渐失调。NK细胞“衰竭”可以解释 NK细胞在晚期癌症中抑制肿瘤生长的失败。虽然NK细胞低反应性 尽管在各种恶性肿瘤中有描述，但在肿瘤中几乎没有“耗竭NK细胞状态”的特征。 转移性疾病，也不可能是这种表型的基础机制。我们现在有证据表明， 细胞在晚期黑素瘤中进行性耗竭。黑色素瘤相关NK细胞是 其特征在于不能增殖、不能产生干扰素γ（IFNγ）或不能杀死靶细胞。（I）down 调节活化受体、IL-2 R亚基和NK细胞调节转录因子（T-bet，Eomes），（ii） 上调抑制性受体和（iii）表达高水平的检查点分子Tim-3，这是一种 与“NK细胞衰竭”相符值得注意的是，Tim-3的阻断基本上逆转了这种表型 和体外衰竭状态（Can. ImmRes. 2014）。然而，最引人注目的是，我们发现患有这种疾病的患者 对伊匹单抗治疗的临床反应自发地恢复了他们的NK细胞功能，尽管事实上， 这些细胞表达很少或不表达CTLA-4（或PD-1或PD-L1），这可能是通过逆转肿瘤相关的细胞凋亡。 全身免疫抑制因此，描述黑色素瘤中NK细胞功能障碍的特征将是至关重要的， 了解肿瘤微环境（TME）中NK细胞生物学的调节，并最终实现 开发在体内恢复先天免疫和适应性免疫的方法。 虽然晚期黑色素瘤患者（IV期）的生存期已通过干预措施延长， 逆转T细胞耗竭，我们假设逆转NK细胞耗竭将有助于 完全恢复消除黑色素瘤细胞所需的免疫反应。为了解决这个 假设，我们的目标是定义黑色素瘤中NK细胞耗竭的谱，并鉴定分子/蛋白质 增强NK细胞耗竭的靶点（目的1）。其次，我们将确定NK细胞耗竭是否可以 逆转，并鉴定相关的生物标志物（目的2）。在目标3中， 我们将开发小鼠模型来定义和测试逆转NK细胞耗竭的干预措施。表征 黑色素瘤中的NK细胞功能障碍对于开发体内恢复免疫力的方法至关重要。

Project summary NK cells are key participants in the initial immune response to tumorigenesis and virus infections, equipped to respond rapidly through induction of cytokines and deployment of cytotoxic activity. A dynamic balance of positive and negative signals regulates NK cell target cell recognition and lysis, through engagement of a variety of activation and inhibitory receptors. However, as cancers advance there is accumulating evidence that NK cells become progressively dysfunctional. NK cell “exhaustion,” could explain the failure of NK cells to contain tumor growth in advanced cancers. While NK cell hyporesponsiveness has been described in various malignancies, there is little characterization of an “exhausted NK cell state” in metastatic disease, nor of the mechanisms that might underlie this phenotype. We now have evidence that NK cells progressively undergo exhaustion in late stage melanoma. Melanoma associated NK cells are characterized by a failure to proliferate, to produce interferon gamma (IFNγ) or to kill target cells. They (i) down regulate activation receptors, IL-2R subunits and NK cell regulatory transcription factors (T-bet, Eomes), (ii) upregulate inhibitory receptors and (iii) express high levels of the checkpoint molecule Tim-3, a phenotype that is consistent with “NK cell exhaustion”. Significantly, blockade of Tim-3 substantially reverses this phenotype and state of exhaustion in vitro (Can. Imm Res. 2014). Most strikingly however, we find that patients who have a clinical response to ipilimumab treatment spontaneously restore their NK cell function, despite the fact that these cells express little or no CTLA-4 (or PD-1 or PD-L1), possibly through reversal of tumor-associated systemic immune suppression. Characterizing NK cell dysfunction in melanoma, therefore, will be critical to understanding the modulation of NK cell biology in the tumor microenvironment (TME), and ultimately towards developing approaches that restore both innate and adaptive immunity, in vivo. Although the survival of advanced melanoma patients (stage IV) has been extended by interventions that reverse T cell exhaustion, we hypothesize that reversal of exhaustion in NK cells will contribute towards the full restoration of immune responses that are required to eliminate melanoma cells. To address this hypothesis, we aim to define the spectrum of NK cell exhaustion in melanoma and identify molecular/protein targets that potentiate NK cell exhaustion (Aim 1). Secondly, we will determine if NK cell exhaustion can be reversed in response to checkpoint blockade inhibition, and identify associated biomarkers (Aim 2). In Aim 3, we will develop murine models to define and test interventions that reverse NK cell exhaustion. Characterizing NK cell dysfunction in melanoma will be critical towards developing approaches that restore immunity, in vivo.