肿瘤免疫微环境中的NK 细胞及免疫治疗

自然杀伤（NK）细胞是一类具有强大抗肿瘤功能的固有淋巴细胞,能够快速识别和杀伤肿瘤细胞,其功能受活化性受 体和抑制性受体的多种信号所调控。但是,肿瘤浸润NK 细胞的杀伤功能由于免疫抑制性肿瘤微环境而失调,甚至会促进肿瘤细胞的免疫逃逸,导致多种免疫疗法临床治疗的效果不佳。肿瘤细胞上调表达抑制性配体、肿瘤微环境中大量抑炎因子及异常的 低氧、低pH 等,都诱导肿瘤浸润NK 细胞杀伤功能受损。近年来,关于肿瘤微环境与肿瘤浸润NK 细胞的研究正处于肿瘤免疫领 域的前沿,已经取得了很多临床研究成果。多项研究表明,肿瘤浸润NK 细胞通常表现为抑制性受体上调、活化性受体下调和代 谢异常等特征,基于此,研究者开发了多种针对性治疗方案,以恢复NK 细胞的杀伤能力。本文在阐述NK 细胞功能活化和抑制 相关机制的基础上,论述了肿瘤浸润NK 细胞的特征及其相应的肿瘤免疫治疗方案。     

肿瘤微环境对NK细胞功能调节的研究进展

自然杀伤(natural killer,NK)细胞作为固有免疫细胞成员之一,不仅能够通过细胞毒作用直接杀伤肿瘤细胞,还可通过释放细胞因子(如趋化因子)调节多种免疫细胞的功能,支持机体后续的适应性免疫应答.然而肿瘤细胞会通过多种机制成功规避NK细胞的识别,肿瘤微环境还能诱导多种免疫细胞功能异常,如髓系来源的抑制细胞(myeloid derived suppressorcells,MDSCs)、M2型肿瘤相关巨噬细胞(M2-tumor-associated macrophage,M2-TAM)、树突状细胞(dendritic cells,DCs)和调节性T细胞(regulatory T cells,Treg)等,通过干扰NK细胞活化相关信号通路或者受体表达,抑制NK细胞的活化和抗肿瘤活性,造成肿瘤免疫逃逸.本文从NK细胞的视角,在讨论NK细胞功能的转录调控机制同时,重点综述肿瘤微环境中多种类型细胞对NK细胞功能调节的最新研究进展.     

子宫内膜癌肿瘤微环境的研究进展

肿瘤微环境是决定肿瘤细胞发生发展的主要影响因素,由肿瘤细胞、基质细胞、细胞外基质共同构成的肿瘤局部的病理微环境。成纤维细胞、血管内皮细胞及免疫炎症细胞等称为基质细胞,在肿瘤进展过程中,基质细胞可通过自分泌、旁分泌的方式分泌多种可溶性因子,与微环境中肿瘤细胞及其他基质细胞相互作用,促进肿瘤细胞的发生、发展、浸润和转移。本文就肿瘤微环境中相关基质细胞与子宫内膜癌恶性行为的关系做一综述。     

T细胞免疫球蛋白黏蛋白3与妇科常见恶性肿瘤相关性的研究进展

T细胞免疫球蛋白黏蛋白3(T cell immunoglobulin mucin 3,Tim-3)是一个新兴的免疫检查点分子，其通过抑制肿瘤微环境中的抗肿瘤免疫反应，降低免疫系统对癌细胞的杀伤及清除，癌细胞最终存活进而增殖、转移，导致肿瘤发生及进展。近年来研究发现Tim-3在宫颈癌、卵巢癌及子宫内膜癌中多为高表达，与妇科肿瘤密切相关，有望成为妇科肿瘤免疫治疗的新靶标。全文就Tim-3与妇科常见恶性肿瘤的相关性研究进展进行综述。     

胰腺癌抑制性免疫微环境促进肿瘤细胞化疗耐药的研究进展

胰腺癌微环境中存在多种免疫抑制细胞,表达不同的细胞因子抑制机体的免疫杀伤功能,在肿瘤发展中发挥重要的作用。这些细胞还能影响化疗药物杀伤肿瘤细胞的功能,促进肿瘤细胞耐药。吉西他滨、白蛋白结合型紫杉醇等胰腺癌一线化疗药物不仅可直接抑制肿瘤细胞增殖,还可作用于免疫细胞间接增强抗肿瘤作用。相反,化疗药物也能增强免疫抑制细胞功能,诱导耐药,促进肿瘤进展。本文就胰腺癌微环境的免疫抑制状态,及其与化疗药物之间作用机制做一综述,旨在从肿瘤免疫微环境的角度优化现有的化疗策略。      

增强NK细胞肿瘤杀伤活性的研究进展

调节其他免疫细胞的功能,是机体天然免疫的主要承担者,也是获得性免疫的核心调节细胞,故NK细胞在抗肿瘤免疫中的地位越来越受到重视,随之增强NK细胞肿瘤杀伤活性的研究也逐步深入.可以通过细胞因子、单抗及多功能抗体介导NK细胞活化,通过调节抑制性信号和活化性信号传递加强NK细胞活性,通过免疫药物刺激及基因修饰提高NK细胞功能等多种途径增强NK细胞的肿瘤杀伤作用.结论:研究增强NK细胞杀伤活性的方法,将促进NK细胞在肿瘤免疫治疗中的应用.     

自然杀伤细胞免疫检查点抑制剂在癌症治疗中的研究进展

近年来许多研究证实免疫检查点抑制剂在多种癌症治疗中的潜力。自然杀伤细胞（natural killer cell,NK）是固有免疫系统的重要组成部分,在肿瘤免疫监视中发挥重要作用。其作用效应依赖于其与抑制和（或）激动受体的结合,无需主要组织相容性复合体（major histocompatibility complex,MHC）便能有效杀伤肿瘤。NK细胞对实体和血液肿瘤有巨大的杀伤潜力,已被越来越多的研究证实是肿瘤免疫治疗的理想靶点。NK细胞上一些新发现的免疫检查点受体被证实在肿瘤微环境中介导NK细胞的功能障碍,是理想的肿瘤免疫治疗靶点。本文将重点论述近年来新发现的免疫检查点受体在调节NK细胞功能中的作用及其在肿瘤免疫治疗中的潜在应用。      

结直肠癌与自然杀伤细胞的相关性探讨北大核心

目的:研究结直肠癌及其配对的癌旁组织的自然杀伤(nature killer,NK)细胞数量及分布情况。方法:结直肠癌及其配对的癌旁组织各40例,以SP免疫组化法检测NK细胞。结果:结直肠癌及其配对的癌旁组织中均未检测到NK细胞的浸润。结论:结直肠癌及其配对的癌旁组织中缺乏NK细胞浸润可能与肿瘤微环境、生理微环境、未知的NK细胞亚型相关,结直肠癌患者可能不适用NK细胞进行免疫治疗。     

自然杀伤细胞肿瘤的研究进展与探索

正自然杀伤(natural killer,NK)细胞肿瘤是一组少见的异质性疾病。基于对正常NK细胞和相关肿瘤认识的进展,WHO造血及淋巴组织肿瘤分类(2008年版)已纳入慢性NK细胞增殖性疾病和NK细胞淋巴母细胞白血病/淋巴瘤,作为新的暂定疾病实体。值得注意的是母细胞NK细胞淋巴瘤(WHO分类2001)现在认为是来源于前体浆细胞样树突细胞的肿瘤,并更名为母细胞浆细胞样树突细胞肿瘤。     

卵巢癌、子宫内膜癌与子宫肌瘤患者PBL表型分析及细胞毒活性变化的研究

众所周知,肿瘤的发生与机体免疫状态密切相关,肿瘤在体内的发生发展正是机体免疫监视系统与肿瘤细胞之间的作用失调所致,免疫监视能力降低肿瘤细胞得以逃逸而生长,在免疫监视系统中,活化的T细胞及其所分泌的细胞因子与NK细胞的作用是其重要的组成,特别是NK细胞(CD56~ 细胞)是在B或T细胞功能基本缺失或不能分化的情况下,以正常形式存在的一种成熟的细胞毒细胞,是机体早期肿瘤免疫监视的重要效应细胞.本研究分析了卵巢癌、子宫内膜癌与子宫叽瘤患者PBL的表型及细胞毒活性变化,结果表明,用IL-2(2000 U/ml)刺激PBL5d后其CD4,CD56及CD25的表达有明显的提高,CD56~ 细胞数有听增加.IL-2     

Early activation and interferon-γ production of tumor-infiltrating mature CD27 high natural killer cells

Natural killer (NK) cells are known to be critically involved in the control of tumors through their direct cytotoxic function, but have also been proposed as an initial source of interferon (IFN)-γ that primes subsequent adaptive tumor-specific immune responses. Although mounting evidence supports the importance of NK cells in antitumor immune responses, the immunological characteristics of NK cells infiltrating the tumor microenvironment and the mechanisms that regulate this process remain unclear. In the present study, we found that NK cells infiltrate early developing MCA205 tumors, and further showed that mature CD27(high) NK cells were the predominant subpopulation of NK cells accumulating in the tumor microenvironment. The tumor-infiltrating NK cells displayed an activated cell surface phenotype and provided an early source of IFN-γ. Importantly, we also found that host IFN-γ was critical for NK cell infiltration into the local tumor site and that the tumor-infiltrating NK cells mainly suppressed tumor growth via the IFN-γ pathway. This work implicates the importance of IFN-γ as a positive regulatory factor for NK cell recruitment into the tumor microenvironment and an effective antitumor immune effector response.     

Inhibition of T cell and natural killer cell function by adenosine and its contribution to immune evasion by tumor cells (Review)

The resistance of many human cancers to immune-based therapies, including adoptive immunotherapy and the administration of therapeutic cancer vaccines, has been attributed to tumor-associated immune suppression, due in part to immunosuppressive molecules located within the tumor microenvironment. Adenosine is a purine nucleoside found within the interstitial fluid of solid tumors at concentrations that are able to inhibit cell-mediated immune responses to tumor cells. It is well established that extracellular adenosine inhibits T lymphocyte activation and effector function, including T cell adhesion to tumor cells and cytotoxic activity, by signaling primarily through A2a and A3 adenosine receptors on the surface of T cells. Importantly, A2a adenosine receptor-deficient mice exhibit enhanced anti-tumor immune responses by CD8+ T cells, as well as a dramatic reduction in the growth of experimental tumors in comparison to wild-type controls. A2a adenosine receptor signaling has also been implicated in adenosine-mediated inhibition of cytokine production and cytotoxic activity by activated natural killer (NK) cells, although the process of NK cell granule exocytosis is apparently suppressed via a distinct and as yet uncharacterized adenosine receptor. In this report, we review the evidence that adenosine is a potent inhibitor of cellular immune responses and may therefore be a major barrier to the successful immunotherapy of human carcinomas. The signaling pathways through which adenosine exerts its inhibitory effects on cell-mediated immune responses are also discussed. The accumulated evidence suggests that the effectiveness of immune-based therapies for solid tumors may be enhanced by selective antagonism of the adenosine receptor subtypes through which adenosine inhibits the anti-tumor activity of T lymphocytes and NK cells.     

Fractalkine mediates natural killer-dependent antitumor responses in vivo

CX3CR1 has been described previously as a marker of human cytotoxic effector cells. We evaluated the possibility of using its ligand, CX3CL1, to redirect immune response against tumors. When murine lymphoma cell lines (EL4 and its derivative EG7) stably transfected with human-CX3CL1 were injected s.c. into C57BL/6 mice, the tumor growth was severely impaired when compared with the growth of control cell lines. This antitumor effect of CX3CL1 was also found in T- and B-cell-deficient Rag1-/- mice but vanished in natural killer (NK) cell-deficient beige mice and in CX3CR1-/- mice, suggesting the involvement of CX3CR1-expressing NK cells. In addition, increased NK cell infiltration was observed in CX3CL1-producing tumors compared with controls. The effect of CX3CR1 on tumor growth required host cytotoxic effector cell functions because both IFNgamma-/- and perforin-/- mice were resistant to CX3CL1 antitumor effect. Finally, intratumoral injection of DNA plasmid coding for a chimeric immunoglobulin presenting the CX3CL1 chemokine domain provided strong antitumor activity. Together, these data demonstrate that the CX3CL1 can reduce incidence and size of lymphoma in vivo through increased recruitment of activated NK cytotoxic cells. These findings offer the first evidence of the potential of chimeric immunoglobulin-chemokines in anticancer therapy.     

Immuno-oncologic Approaches: CAR-T Cells and Checkpoint Inhibitors

Advances in understanding myeloma biology have shown that disease progression is not only the consequence of intrinsic tumor changes but also of interactions between the tumor and the microenvironment in which the cancer grows. The immune system is an important component of the tumor microenvironment in myeloma, and acting on the immune system is an appealing new treatment strategy. There are 2 ways to act toward immune cells and boost antitumor immunity: (1) to increase antitumor activity (acting on T and NK cytotoxic cells), and (2) to reduce immunosuppression (acting on myeloid-derived stem cells and T regulatory cells). Checkpoint inhibitors and adoptive cell therapy (ACT) are 2 of the main actors, together with monoclonal antibodies and immunomodulatory agents, in the immune-oncologic approach. The aim of checkpoint inhibitors is to release the brakes that block the action of the immune system against the tumor. Anti-programmed death-1 (PD-1) and PD-1-Ligand, as well as anti-CTLA4 and KIR are currently under evaluation, as single agents or in combination, with the best results achieved so far with combination of anti–PD-1 and immunomodulatory agents. The aim of ACT is to create an immune effector specific against the tumor. Preliminary results on chimeric antigen receptor (CAR) T cells, first against CD19, and more recently against B-cell maturation antigen, have shown to induce durable responses in heavily pretreated patients. This review focuses on the most recent clinical results available on the use of checkpoint inhibitors and CAR-T cells in myeloma, in the context of the new immune-oncologic approach.     

Newcastle disease virus mediates pancreatic tumor rejection via NK cell activation and prevents cancer relapse by prompting adaptive immunity

Pancreatic cancer is the 8th most common cause of cancer‐related deaths worldwide and the tumor with the poorest prognosis of all solid malignancies. In 1957, it was discovered that Newcastle disease virus (NDV) has oncolytic properties on tumor cells. To study the oncolytic properties of NDV in pancreatic cancer a single dose was administered intravenously in a syngeneic orthotopic tumor model using two different murine pancreatic adenocarcinoma cell lines (DT6606PDA, Panc02). Tumor growth was monitored and immune response was analyzed. A single treatment with NDV inhibited DT6606PDA tumor growth in mice and prevented recurrence for a period of three months. Tumor infiltration and systemic activation of NK cells, cytotoxic and helper T‐cells was enhanced. NDV‐induced melting of Panc02 tumors until d7 pi, but they recurred displaying unrestricted tumor growth, low immunogenicity and inhibition of tumor‐specific immune response. Arrest of DT6606PDA tumor growth and rejection was mediated by activation of NK cells and a specific antitumor immune response via T‐cells. Panc02 tumors rapidly decreased until d7 pi, but henceforth tumors characterized by the ability to perform immune‐regulatory functions reappeared. Our results demonstrated that NDV‐activated immune cells are able to reject tumors provided that an adaptive antitumor immune response can be initiated. However, activated NK cells that are abundant in Panc02 tumors lead to outgrowth of nonimmunogenic tumor cells with inhibitory properties. Our study emphasizes the importance of an adaptive immune response, which is initiated by NDV to mediate long‐term tumor surveillance in addition to direct oncolysis.     

Restoration of natural killer cell cytotoxicity by VEGFR-3 inhibition in myelogenous leukemia

Acute myeloid leukemia (AML) cells in vivo are constantly exposed to lymphangiogenic cytokines such as VEGF-C. However, it is poorly understood how the VEGF-C signaling modulates the immune functions in the tumor microenvironment. We have previously reported that natural killer (NK) cells in AML patients strongly upregulated VEGFR-3, the major VEGF-C receptor, and that the VEGFR-3 expression level in NK cells inversely correlates with their cytotoxic potential. These findings have led us to hypothesize that VEGFR-3 inhibition may reinstate the cytotoxic capacity of the AML-associated NK cells. To address this hypothesis, we employed a pharmaceutical approach to block the VEGFR-3 function in the murine model of syngeneic myelogenous leukemia. Using various molecular and cellular analyses, we assessed the correlation between VEGFR-3 inhibition and NK cell cytotoxicity. Indeed, we found that leukemic environment is highly enriched with lymphangiogenic stimuli, and that VEGFR-3 inhibition restored NK cell killing function with an increased IFN-γ level, providing a therapeutic implication of VEGFR-3 against AML. Together, we demonstrate the therapeutic value of functional modulation of NK cells by blocking VEGFR-3, and provide a possibility of advanced therapeutic approaches using immune cells against myelogenous leukemia.     

Profound coordinated alterations of intratumoral NK cell phenotype and function in lung carcinoma

Both the innate and adaptive immune systems contribute to tumor immunosurveillance in mice and humans; however, there is a paucity of direct evidence of a role for natural killer (NK) cells in this important process. In this study, we investigated the intratumoral phenotypic profile and functions of NK cells in primary human tumor specimens of non-small cell lung carcinoma (NSCLC). We used in situ methods to quantify and localize NK cells using the NKp46 marker and we characterized their phenotype in blood, tumoral, and nontumoral samples of NSCLC patients. Intratumoral NK cells displayed a profound and coordinated alteration of their phenotype, with a drastic reduction of NK cell receptor expression specifically detected in the tumoral region. According to their altered phenotype, intratumoral NK cells exhibited profound defects in the ability to activate degranulation and IFN-γ production. We found that the presence of NK cells did not impact the clinical outcome of patients with NSCLC. Finally, we showed that tumor cells heterogeneously express ligands for both activating and inhibitory NK receptors. Taken together, our results suggest that the NSCLC tumor microenvironment locally impairs NK cells, rendering them less tumorcidal and thereby supportive to cancer progression.     

髓源抑制性细胞的功能及其逆转策略

髓源抑制性细胞（myeloid-derived suppressor cell,MDSC）是在骨髓中产生的一群具有高度异质性的免疫抑制细胞, 在 肿瘤等病理状态下大量聚集,是促进肿瘤进展、降低患者对传统治疗反应性的关键因素。近年来,免疫检查点阻断剂和基因工程 T细胞过继回输治疗延长了许多晚期恶性肿瘤患者的生存期,但上述免疫疗法在肺癌、结直肠癌等实体瘤中有效率仅为 15%~40%,这与实体瘤免疫抑制微环境密切相关。MDSC在肿瘤微环境中聚集,通过抑制T细胞或NK细胞增殖及功能减弱宿主 抗肿瘤免疫反应,是患者对免疫治疗耐受的关键机制。因此,明确MDSC聚集及功能特征是探索提高免疫治疗效果的重要研究 方向。本文将系统阐述MDSC的产生、聚集及其免疫抑制功能的调控机制,概述目前靶向MDSC治疗的最新研究进展。