NK cell exhaustion in metastatic melanoma

项目总结 NK细胞是肿瘤形成和病毒感染的初始免疫反应的关键参与者， 具备通过诱导细胞因子和部署细胞毒活性进行快速反应的能力。一种动态 正负信号平衡调节NK细胞靶细胞识别和裂解 参与多种激活和抑制受体。然而，随着癌症的发展，有 越来越多的证据表明，NK细胞逐渐功能失调。NK细胞“衰竭”可以解释 晚期癌症患者NK细胞不能抑制肿瘤生长。而NK细胞的低反应性 在不同的恶性肿瘤中都有描述，但很少有人描述在 转移性疾病，也不是这种表型可能的机制。我们现在有证据表明NK 在黑色素瘤晚期，细胞逐渐耗尽。与黑色素瘤相关的NK细胞是 其特征是不能增殖、不能产生干扰素γ或不能杀死靶细胞。他们(I)倒下了 调节激活受体、IL-2R亚单位和NK细胞调节转录因子(T-bet、eome)，(Ii) 上调抑制性受体和(Iii)高水平表达检查点分子Tim-3，这是一种表型 与“NK细胞衰竭”相一致。值得注意的是，TIM-3的阻断实质上逆转了这种表型 和体外力竭状态(Can.IMM Res.2014)。然而，最令人惊讶的是，我们发现患有 对ipilimumab治疗的临床反应自发地恢复他们的NK细胞功能，尽管事实是 这些细胞很少表达或不表达CTLA-4(或PD-1或PD-L1)，可能是通过逆转与肿瘤相关的 全身免疫抑制。因此，确定黑色素瘤中NK细胞功能障碍的特征对 了解NK细胞生物学在肿瘤微环境(TME)中的调节，并最终走向 开发恢复体内先天免疫和获得性免疫的方法。 尽管通过干预延长了晚期黑色素瘤患者(IV期)的生存期 逆转T细胞衰竭，我们假设NK细胞衰竭的逆转将有助于 完全恢复清除黑色素瘤细胞所需的免疫反应。要解决这个问题 假设，我们的目标是定义黑色素瘤中NK细胞耗竭的光谱并确定分子/蛋白质 增强NK细胞耗竭的靶点(目标1)。其次，我们将确定NK细胞是否可以耗尽 逆转对检查点封锁的抑制，并确定相关的生物标志物(目标2)。在《目标3》中， 我们将开发小鼠模型来定义和测试逆转NK细胞衰竭的干预措施。刻画 黑色素瘤中的NK细胞功能障碍对于开发体内恢复免疫的方法至关重要。

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.