NKT细胞对肿瘤免疫调节的研究进展

自然杀伤T（NKT）细胞是一类重要的独立天然淋巴细胞亚群,不断有研究表明其在机体免疫应答过程中发挥重要作用。不同NKT细胞亚群及功能不断被发现,不同亚群对肿瘤免疫的影响不尽相同,各亚群之间的相互作用机制不十分清楚,有待进一步探索。深入了解NKT细胞在肿瘤免疫中的作用,对肿瘤的治疗有重要意义。     

Potent anti-tumor killing activity of the multifunctional Treg cell line HOZOT against human tumors with diverse origins

The T cell line HOZOT has a unique FOXP3+CD4+ CD8+CD25+ phenotype, exhibits suppressive activity in allogeneic mixed lymphocyte reactions (MLR), and produces IL-10, defining HOZOT as regulatory T cells (Tregs). Interestingly, in addition to possessing a suppressive Treg ability, HOZOT was also found to show cytotoxicity against certain representative human cancer cell types. In order to disclose the range of anti-tumor activity by HOZOT, we screened it by using a panel of twenty human tumor cell lines with different origins. Consequently, HOZOT showed potent cytocidal effects against a wide spectrum of neoplastic cells including carcinomas, sarcomas, mesotheliomas and glioblastomas except for hematopoietic malignancies. Its anti-tumor activity was strong enough with an E:T ratio of 4:1, which is considered to be more effective than that by conventional CTLs. Furthermore, an in vivo representative mouse tumor model by implanting human colon adenocarcinoma cells revealed that adoptive transfer of HOZOT almost completely eradicated disseminated lesions on peritoneum, markedly reduced metastases in lung and liver, and dramatically decreased bloody ascites caused by peritoneal carcinomatosis. Treatment of the tumor model mice by HOZOT with an E:T ratio of 2:1 even indicated the prolongation of their survival, although not reaching obvious statistical significance. In vitro blocking experiments using antibodies and inhibitors suggested that the cytotoxic mechanism of HOZOT against tumors is different from conventional cytotoxic cells such as CTL, NK or NKT cells. Altogether, our studies demonstrated the potent killing activity of HOZOT against a broad range of human malignancies, which indicates that HOZOT is a powerful tool in immunotherapy for advanced stage tumors.     

Inhibition of BCL11B expression leads to apoptosis of malignant but not normal mature T cells

The B-cell chronic lymphocytic leukemia (CLL)/lymphoma 11B gene (BCL11B) encodes a Krüppel-like zinc-finger protein, which plays a crucial role in thymopoiesis and has been associated with hematopoietic malignancies. It was hypothesized that BCL11B may act as a tumor-suppressor gene, but its precise function has not yet been elucidated. Here, we demonstrate that the survival of human T-cell leukemia and lymphoma cell lines is critically dependent on Bcl11b. Suppression of Bcl11b by RNA interference selectively induced apoptosis in transformed T cells whereas normal mature T cells remained unaffected. The apoptosis was effected by simultaneous activation of death receptor-mediated and intrinsic apoptotic pathways, most likely as a result of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) upregulation and suppression of the Bcl-xL antiapoptotic protein. Our data indicate an antiapoptotic function of Bcl11b. The resistance of normal mature T lymphocytes to Bcl11b suppression-induced apoptosis and restricted expression pattern make it an attractive therapeutic target in T-cell malignancies.     

CD3+CD56+NKT细胞及CD3-CD56+NK细胞在恶性肿瘤患者的临床意义研究

背景与目的细胞毒性淋巴细胞在抗肿瘤免疫效应中发挥着重要作用,CD3 CD56 NKT细胞作为一类新的具有细胞毒性的效应细胞,目前关于其抗肿瘤意义的探讨主要集中于血液系统恶性疾病,而在实体肿瘤中的应用和临床价值研究尚少。本研究旨在初步探讨抗肿瘤细胞CD3 CD56 NKT细胞及CD3-CD56 NK细胞在恶性肿瘤患者外周血的表达状态及其临床意义。方法采用流式细胞术分析118例恶性肿瘤患者(55例肺癌患者和63例乳腺癌患者)及46例健康对照组外周血中的T细胞亚群及CD3 CD56 NKT细胞、CD3-CD56 NK细胞表达。结果恶性肿瘤患者组CD3 CD8 T细胞、CD3 CD56 NKT细胞以及CD3-CD56 NK细胞表达率均明显高于健康对照组(P<0.01)。肺癌患者中以CD3 CD8 T细胞和CD3 CD56 NKT细胞明显增加为主;乳腺癌患者中以CD3 CD56 NKT细胞和CD3-CD56 NK细胞明显增加为主。结论CD3 CD56 NKT细胞在肺癌和乳腺癌患者的抗肿瘤效应中占据重要地位,而CD3 CD8 CTL和CD3-CD56 NK细胞在不同类型肿瘤患者中具有不同的重要性。     

Effect of CXCL12 and Its Receptors on Unpredictable Renal Cell Carcinoma

Chemokines are chemotactic cytokines that participate in numerous cell functions during hematopoiesis, morphogenesis, inflammation, neovascularization, and autoimmune diseases and cancer. They achieve their functions on binding to their G protein-coupled receptors. CXCL12, or stromal cell-derived factor-1, is a homeostatic chemokine secreted by fibroblasts, macrophages, and endothelial cells. It binds to CXC receptor 4 (CXCR4), also known as fusin (CD184), and alternate CXC receptor 7 (CXCR7), also known as atypical chemokine receptor 3. The CXCL12/CXCR4 axis participates in homing of hematopoietic stem cells and the development and production of B and T lymphocytes, plasmacytoid dendritic cells, and natural killer cells. It has been examined in > 20 different malignancies. CXCL12 plays an important role in tumor metastasis because it mediates the migration of tumor cells through the endothelial vessel wall and extracellular matrix. Its expression has been highest in common metastatic sites such as the brain, bone marrow, lymph nodes, and liver. CXCR4 is expressed by tumor cells in prostate, breast, lung, and other malignancies. Numerous studies have shown its correlation with a poor prognosis, recurrence-free survival, and poor overall survival. The present review has addressed the structure and function of CXCL12 and its receptors and the effect CXCL12/CXCR4 axis has on the pathogenesis and clinical development of renal cell carcinoma, one of the most aggressive cancers in urology, with limited therapeutic options.     

Expansion of natural killer (NK) and natural killer-like T (NKT)-cell populations derived from patients with B-chronic lymphocytic leukemia (B-CLL): a potential source for cellular immunotherapy.

B-cell chronic lymphocytic leukemia (B-CLL) is the most common leukemia in the Western world. It is currently an incurable disease, making new treatment options such as immunotherapy desirable. Monoclonal antibodies (Mabs) to surface antigens of the tumor cell is one option. Administration of cytotoxic cells such as natural killer (NK) and natural killer-like T (NKT) cells expanded in vitro might be a useful treatment modality alone or in combination with MAbs. A limiting step in the development of successful cellular immunotherapy has been the availability of appropriate cytotoxic cells. Here, we report the feasibility of expanding populations of the human killer cells, CD3-CD56+ NK and CD3+CD56+ NKT cells, from peripheral blood mononuclear cells (PBMCs) of B-CLL patients. The influence of tumor B cells on the in vitro expansion of killer cells was assessed by depleting B cells from PBMCs by microbead separation before culture. The 21-day cultures from both B-cell- and non-B-cell-depleted PBMC showed a marked expansion of NK cells, and also of T cells, among which almost half had the NKT phenotype. Depletion of B cells before culture did not change the expansion rates of NK and NKT cells significantly. In patients with progressive B-CLL, NK cell expansion capacity was improved after fludarabine treatment when compared to samples obtained before treatment. Repeated samples of PBMCs from individual untreated patients with both indolent and progressive disease cultured under identical conditions gave similar NK cell expansion rates. Expanded killer cell populations had cytotoxic function against the NK-sensitive target K562 cell line and expressed high levels of Granzyme B. From our studies, we conclude that NK cells as well as NKT cells from the peripheral blood of B-CLL patients can be expanded, and that these cells have cytotoxic capacity.     

Peripheral blood IFN-gamma-secreting Valpha24+Vbeta11+ NKT cell numbers are decreased in cancer patients independent of tumor type or tumor load

Natural killer T (NKT) cells are CD1d-restricted lymphoid cells and are characterized by an invariant T-cell receptor, which in humans consists of a Valpha24 chain paired with a Vbeta11 chain. These cells are known for their rapid production of large amounts of cytokines (e.g., IFN-gamma and IL-4), thereby modulating other cells of the immune system such as T cells, NK cells and dendritic cells. NKT cells have been reported to play important regulatory roles in many immune responses, including antitumor immune responses. Here, we demonstrate an age-dependent decrease in circulating Valpha24(+)Vbeta11(+) NKT cell numbers in both healthy controls and cancer patients and demonstrate that in both groups females have higher NKT cell levels compared to males. In a large group of 120 cancer patients, we show that circulating Valpha24(+)Vbeta11(+) NKT cell numbers are about 50% lower than in age- and gender-matched healthy controls and that this decrease is independent of tumor type or tumor load. This decrease was not restored upon tumor removal by means of surgery or radiotherapy. Even though the percentage of NKT cells that secrete IFN-gamma, as detected by ELISPOT, is normal in cancer patients, the absolute number of circulating IFN-gamma-secreting NKT cells is reduced. Together, our results suggest that the reduced circulating Valpha24(+)Vbeta11(+) NKT cell numbers in cancer patients are not affected by tumor load, but might actually reflect a risk factor for tumor development, e.g., by hampering efficient tumor immunosurveillance.     

食管癌患者外周血中自然杀伤性T细胞含量的检测及其临床意义

 　目的　研究食管癌患者外周血中自然杀伤性（NK）T细胞在手术前后的表达情况。方法　采用流式细胞术（FCM）分析59例食管癌患者手术前后外周血中CD3、CD56、CD4、CD8抗体的表达,研究NKT细胞及其亚群的表达情况及所占比例。结果　随着CD+3 CD+56 CD+8／CD+3 CD+56 CD+4的比值逐渐升高,Ⅲ～Ⅳ期食管癌患者的比例逐渐降低,ANOVA示组间差异有统计学意义（P＜0.05）;CD+3 CD+56 CD+8／CD+3 CD+56 CD+4的比值与CD+3 CD+56 CD+4 NKT细胞非线性相关;CD+3 CD+56 CD+8 NKT细胞与NK细胞正相关,与CD+3 T细胞负相关。结论　CD+3 CD+56 CD+8／CD+3 CD+56 CD+4 的比值可能与肿瘤负荷有关,并且有助于判断食管癌患者的疾病程度及预后。     

Human CD4+ CD25+ regulatory T cells suppress NKT cell functions

CD4+CD25+ regulatory T cells play an important role in peripheral tolerance. These cells have been reported to be capable of suppressing the response of CD4+CD25- T cells in vitro. The depletion of these cells evokes effective immune responses to tumor cells in vivo. In this study, we demonstrate that CD4+CD25+ T cells also suppress all subsets of Valpha24+NKT cells (Valpha24+CD4-CD8- double negative, Valpha24+CD4+, and Valpha24+CD8+) in both proliferation and cytokine production [IFN-gamma, interleukin-4 (IL-4), IL-13, and IL-10]. This suppression is mediated by cell-to-cell contact but not by a humoral factor or the inhibition of antigen-presenting cells. Moreover, the cytotoxic activity of Valpha24+NKT cells against some tumor cell lines is suppressed by CD4+CD25+ T cells. This finding is important in developing an effective immunotherapy for cancer.     

树突状细胞-细胞因子诱导的杀伤细胞对恶性血液肿瘤患者免疫功能的影响

目的 观察应用树突状细胞-细胞因子诱导的杀伤细胞（DC-CIK细胞）治疗恶性血液肿瘤对患者外周血T淋巴细胞亚群和免疫蛋白的影响.方法 选择25例恶性血液肿瘤患者,采集外周血单个核细胞,经体外培养获得DC-CIK细胞,并将质检合格的DC-CIK细胞分4次回输给患者,分别于治疗前和治疗后3周抽取外周静脉血,检测T淋巴细胞亚群及免疫球蛋白变化情况,与30例非肿瘤患者进行比较分析,同时观察治疗过程中的不良反应.结果 25例患者DC-CIK细胞治疗后外周血中的CD3＋、CD3＋ CD8＋、CD3＋ CD16＋ CD56＋、CD3-CD16＋ CD56＋细胞比例较输注前明显增加（P＜0.05）,CD3＋ CD4＋T细胞比例无明显变化（P＞0.05）;外周血免疫球蛋白（IgG、IgM、IgA）浓度无明显变化（P＞0.05）.DC-CIK细胞治疗过程中有2例出现短暂性低热,均可自行缓解.恶性血液肿瘤患者在DC-CIK细胞治疗前与非肿瘤患者比较,外周血CD3＋、CD4＋、NK及NKT细胞比例明显下降（P＜0.05）,外周血中的IgG、IgM及IgA浓度无明显变化（P＞0.05）.结论 DC-CIK细胞免疫治疗能显著提高恶性血液肿瘤患者体内的肿瘤杀伤性T细胞及其效应细胞的数量,改善恶性血液肿瘤患者免疫失衡状态,增强机体抗肿瘤免疫功能,且安全有效,为恶性血液肿瘤的治疗提供了新的选择.     

Natural killer T cell ligand alpha-galactosylceramide inhibited lymph node metastasis of highly metastatic melanoma cells.

The role of natural killer T (NKT) cells in the prevention of multiple tumor metastasis was examined. The i.v. inoculation of a highly metastatic subline of B16-BL6 (B16-BL6-HM) melanoma cells resulted in the formation of metastatic nodules in lymph nodes in addition to lung, intrapleural cavity, and ovary. However, treatment of the mice with the NKT cell ligand alpha-galactosylceramide (alpha-GalCer) three times from 1 day after B16-BL6-HM melanoma inoculation caused a significant inhibition of multiple metastasis. Lymph node metastasis of B16-BL6-HM was almost completely blocked by alpha-GalCer treatment. This antimetastatic effect of alpha-GalCer was abolished in NKT cell-deficient mice. These results suggest that alpha-GalCer-activated NKT cells played a critical role in the prevention of lymph node metastasis of melanoma cells.     

Multidimensional scaling analysis identifies pathological and prognostically relevant profiles of circulating T‐cells in chronic lymphocytic leukemia

Antitumor immunity in chronic lymphocytic leukemia (CLL) is hampered by highly dysfunctional T‐cells. Although certain T‐cell subsets have been reported to be of prognostic significance in this disease, their interplay is complex and it remains incompletely understood which of these subsets significantly drive CLL progression. Here, we determined immunological profiles of 24 circulating T‐cell subsets from 79 untreated individuals by multiparametric flow cytometry. This screening cohort included healthy donors, patients with monoclonal B‐cell lymphocytosis (MBL), Rai 0 CLL and advanced CLL. We applied multidimensional scaling analysis as rigorous and unbiased statistical tool to globally assess the composition of the circulating T‐cell environment and to generate T‐cell scores reflecting its integrity. These scores allowed clear distinction between advanced CLL and healthy controls, whereas both MBL and Rai 0 CLL showed intermediate scores mirroring the biological continuum of CLL and its precursor stages. T‐cell stimulation and suppression assays as well as longitudinal T‐cell profiling showed an increasingly suppressive regulatory function initiating at the MBL stage. Effector function was impaired only after transition to CLL and partially recovered after chemoimmunotherapy. In an independent validation cohort of 52 untreated CLL cases, aberrant T‐cell profiles were significantly associated with shorter time to treatment independently of other prognostic parameters. Random forest modeling predicted regulatory T‐cell, gamma/delta and NKT‐cells, as well as exhaustion of the CD8+ subset as potential drivers of progression. Our data illustrate a pathological T‐cell environment in MBL that evolves toward a more and more suppressive and prognostically relevant profile across the disease stages.     

Natural Killer T Cell Ligand α-Galactosylceramide Inhibited Lymph Node Metastasis of Highly Metastatic Melanoma Cells

The role of natural killer T (NKT) cells in the prevention of multiple tumor metastasis was examined. The i.v. inoculation of a highly metastatic subline of B16-BL6 (B16-BL6-HM) melanoma cells resulted in the formation of metastatic nodules in lymph nodes in addition to lung, intrapleural cavity, and ovary. However, treatment of the mice with the NKT cell ligand α-galactosylceramide (α-GalCer) three times from 1 day after B16-BL6-HM melanoma inoculation caused a significant inhibition of multiple metastasis. Lymph node metastasis of B16-BL6-HM was almost completely blocked by α-GalCer treatment. This antimetastatic effect of α-GalCer was abolished in NKT celldeficient mice. These results suggest that α-GalCer-activated NKT cells played a critical role in the prevention of lymph node metastasis of melanoma cells.     

Dysfunctions of innate and adaptive immune tumor microenvironment in Waldenström macroglobulinemia

Waldenström macroglobulinemia (WM) is a rare subtype of non-Hodgkin lymphoma characterized by malignant lymphoplasmacytic cells in the bone marrow (BM). To dissect the pathophysiology of WM, we evaluated clonal cells by mapping of B cell lymphomagenesis with adaptive and innate immune tumor microenvironment (TME) in the BM of WM patients using mass cytometry (CyTOF). In-depth immunophenotypic profiling of WM cells exhibited profound expansion of clonal cells in both unswitched and switched memory B cells and also plasma cells with aberrant expression variations. WM B lymphomagenesis was associated with reduction of most B cell precursors assessed with the same clonally restricted light chain and phenotypic changes. The immune TME was infiltrated by mature monocytes, neutrophils and adaptive T cells, preferentially subsets of effector T helper, effector CTL and effector memory CTL cells that were associated with superior overall survival (OS), in contrast to progenitors of T cells and myeloid/monocytic lineage subsets that were suppressed in WM cohort. Moreover, decrease in immature B and NKT cells was related to worse OS in WM patients. Innate and adaptive immune subsets of WM TME were modulated by immune checkpoints, including PD-1/PD-L1&PD-L2, TIGIT/PVR, CD137/CD137-L, CTLA-4, BTLA and KIR expression. The response of ibrutinib treatment to the reduction of clonal memory B cell was associated with high levels of immature B cells and effector memory CTL cells. Our study demonstrates that CyTOF technology is a powerful approach for characterizing the pathophysiology of WM at various stages, predicting patient risk and monitoring the effectiveness of treatment strategies.     

Allo‐reactive T cells for the treatment of hematological malignancies

Several mechanisms can be responsible for control of hematological tumors by allo‐reactive T cells. Following allogeneic stem cell transplantation (alloSCT) donor T cells recognizing genetic disparities presented on recipient cells and not on donor cells are main effectors of tumor control, but also of the detrimental graft versus host disease (GVHD). Since after transplantation normal hematopoiesis is of donor origin, any T cell response directed against polymorphic antigens expressed on hematopoietic recipient cells but not on donor cells will result in an anti‐tumor response not affecting normal hematopoiesis. After fully HLA‐matched alloSCT, T cells recognizing polymorphic peptides derived from proteins encoded by genes selectively expressed in hematopoietic lineages may result in anti‐tumor responses without GVHD. Due to the high susceptibility of hematopoietic cells for T cell recognition, a low amplitude of the overall T cell response may also be in favor of the anti‐tumor reactivity in hematological malignancies. A mismatch between donor and patient for specific HLA‐alleles can also be exploited to induce a selective T cell response against patient (malignant) hematopoietic cells. If restricting HLA class II molecules are selectively expressed on hematopoietic cells under non‐inflammatory circumstances, allo HLA class‐II responses may control the tumor with limited risk of GVHD. Alternatively, T cells recognizing hematopoiesis‐restricted antigens presented in the context of mismatched HLA alleles may be used to treat patients with hematological cancers. This review discusses various ways to manipulate the allo‐immune response aiming to exploit the powerful ability of allo‐reactive T‐cells to control the malignancies without causing severe damage to non‐hematopoietic tissues.     

Molecular identification of GD3 as a suppressor of the innate immune response in ovarian cancer

Tumors often display mechanisms to avoid or suppress immune recognition. One such mechanism is the shedding of gangliosides into the local tumor microenvironment, and a high concentration of circulating gangliosides is associated with poor prognosis. In this study, we identify ganglioside GD3, which was isolated from the polar lipid fraction of ovarian cancer-associated ascites, as an inhibitory factor that prevents innate immune activation of natural killer T (NKT) cells. Purified GD3 displayed a high affinity for both human and mouse CD1d, a molecule involved in the presentation of lipid antigens to T cells. Purified GD3, as well as substances within the ascites, bound to the CD1d antigenic-binding site and did not require additional processing for its inhibitory effect on NKT cells. Importantly, in vivo administration of GD3 inhibited α-galactosylceramide (α-GalCer)-induced NKT cell activation in a dose-dependent manner. These data therefore indicate that ovarian cancer tumors may use GD3 to inhibit the antitumor NKT cell response as an early mechanism of tumor immune evasion.     

调节性T细胞与肿瘤免疫

调节性T细胞( Treg)是一类有负调节作用的T细胞亚群,包括CD4+ Treg、CD8+ Treg、NKT Treg和DN Treg细胞等4大类,主要发挥抑制性免疫调节功能,是肿瘤免疫逃逸的重要因素.这些机制包括分泌多种免疫抑制性细胞因子、分泌颗粒酶和穿孔素杀伤效应细胞、竞争和抑制IL-2、通过T淋巴细胞毒性相关抗原(CTLA)-4影响Treg的分化和增殖等.以Treg及免疫抑制性分子作为靶点,清除Treg,控制Treg的数量和功能,增强机体对肿瘤的免疫应答,为肿瘤免疫治疗提供了新思路.     

肿瘤休眠的机制及其意义

非肿瘤死亡患者尸检常见滤泡性淋巴瘤、前列腺癌、乳腺癌等休眠肿瘤,而血液系统恶性肿瘤细胞的休眠与疾病的发生、发展和治疗密切相关。休眠是生物在生存竞争中普遍采用的策略,作为体内新生物的肿瘤保留了这类基本性状。肿瘤休眠的机制是近年来备受关注的研究课题,不仅具有理论意义,而且对肿瘤防治有指导作用,可能开拓新的防治途径,有助于对“过度诊断”“过度治疗”进一步认识,为“精准医学”提供新线索。文章介绍了肿瘤休眠的细胞机制及免疫和血管生成调控机制,讨论其临床意义和应用前景,并展望了深入研究的可能途径,以期为血液系统恶性肿瘤的诊疗提供新线索。