记忆性干细胞样T细胞在肿瘤治疗应用中的研究进展

记忆性干细胞样T细胞(stem memory T cells,TSCM)是最近几年发现的一个细胞亚群,约占外周血中总的CD4+T细胞和CD8+T细胞的2％～4％,是记忆性T细胞的早期分化阶段,具有记忆性细胞和干细胞的特点,基因谱介于初始T细胞和中央记忆T细胞之间.记忆性干细胞样T细胞具有自我更新和长期存活能力,这些特点使它们成为肿瘤领域关注的热点.本文将简述记忆性干细胞样T细胞的一些特点,以及它们在肿瘤治疗中的应用.     

胆固醇代谢调控CD8+T细胞抗肿瘤作用的研究进展

CD8+T细胞又名细胞毒性T淋巴细胞(cytotoxic T lymphocyte,CTL),具有直接杀死病原体感染细胞和癌细胞的作用.然而,CD8+T细胞常常丧失其效应功能,继而限制肿瘤微环境中的抗肿瘤免疫,因此,如何重新激活CD8+T细胞的抗肿瘤效力是目前需要解决的问题.最近研究发现,胆固醇代谢在肿瘤中发挥重要作用...     

CD4~+T 细胞与肿瘤免疫

CD4~+T细胞不仅辅助激活CD8~+T细胞,而且对记忆性细胞毒性T淋巴细胞(CTL)应答的产生和维持起重要作用,并具有直接的抗肿瘤功能.另外,CD4~+CD25~+ 调节性T细胞(Tregs)具有免疫负调控功能,在肿瘤免疫抑制及免疫逃逸中发挥重要作用,是肿瘤免疫治疗失败的重要原因.近年肿瘤免疫治疗已获得很大进步,相关肿瘤疫苗的研究也备受关注.     

组织驻留CD8+T细胞在肿瘤中的研究进展

组织驻留记忆 T 细胞（ tissue-resident memory T cells，TRMs）作为一种特殊的记忆T细胞，在免疫应答中发挥着极其重要的作用。其特征是可表达归巢受体，从而具备驻留特性，因此能够驻留在外周组织器官中，当病原体侵袭时可以迅速反应。目前，TRMs（尤其是CD8+TRMs）与肿瘤的关系及其在抗肿瘤中的应用被愈加重视，一方面是CD8+TRMs可以通过分泌颗粒酶B、穿孔素和INF-γ等因子直接杀伤肿瘤细胞，另一方面一些抗肿瘤措施（如放化疗、免疫治疗等）可以使CD8+TRMs在肿瘤组织中富集，从而进一步提高治疗的效果。本文就CD8+TRMs的亚群分类、在肿瘤中如何调控形成以及其在肿瘤治疗中的作用等方面的研究进展进行综述。      

CX3CR1+ CD8+ T细胞在肿瘤免疫治疗中作用的研究进展

趋化因子是免疫系统的重要组成部分,趋化因子CX3CL1因其独特的分子结构和双重的存在形式与其受体CX3CR1 共同影响免疫细胞的募集和归巢,参与多种肿瘤发生和肿瘤免疫过程。趋化因子受体CX3CR1响应CX3CL1的趋化作用。同 时,CX3CR1的表达指示CD8+ T细胞的效应分化状态,CX3CR1+ CD8+ T细胞具有细胞毒性和抗原特异性。在肿瘤微环境中,相比 CX3CR1- CD8+ T细胞,CX3CR1+ CD8+ T细胞表面的共抑制分子表达少、杀伤功能活跃。因此,CX3CR1对于CD8+ T细胞等淋巴 细胞的多重意义使其在肿瘤的细胞免疫治疗,如CAR-T细胞治疗中具有应用前景。在肾细胞癌、黑色素瘤和非小细胞肺癌的 PD-1靶向治疗中,外周血CX3CR1+ CD8+ T细胞的占比与疗效正相关,提示CX3CR1也是早期预测免疫治疗疗效的分子标志物。 尽管CX3CR1+ CD8+ T细胞功能活跃,但此群细胞处于终末分化状态,增殖能力和记忆效应差,不具有长久的保护作用。如何使 CAR-T 细胞在体内维持抗肿瘤作用一直是研究者积极探索的方向,也是将 CX3CR1 应用于 CAR-T 细胞免疫治疗需要克服的 难关。     

调节性T细胞与肿瘤

调节性T（regulatory T, Treg）细胞是一群具有抑制其他免疫细胞功能的负调控细胞，包括CD4+ Treg、CD8+ Treg、NKT Treg 和双阴性（double negative，DN）Treg细胞等四大类。研究显示，肿瘤微环境中Treg细胞数量升高，且这些升高的 Treg细胞能抑制抗肿瘤免疫、降低肿瘤免     

CD4+T细胞与肿瘤免疫

在肿瘤免疫中细胞免疫发挥着重要作用,其中T细胞介导的特异性免疫应答反应更为重要.近年来CD4+T细胞在抗肿瘤免疫中的作用越来越受到重视.在肿瘤免疫中CD4+T细胞启动后可以通过多种机制启动细胞毒性T淋巴细胞(CTL),维持和加强CTL的抗肿瘤反应,并且可以作为效应细胞发挥抗肿瘤作用,CD4+T细胞中的一个亚群细胞CD4+ CD25+T调节细胞对肿瘤免疫有抑制作用.     

组织驻留记忆T细胞及其在三阴性乳腺癌中的研究进展

T淋巴细胞在实体肿瘤的抗肿瘤反应中起着重要作用，在多种实体肿瘤中，肿瘤特异性记忆T细胞可能在控制肿瘤细胞生长、限制肿瘤细胞扩散方面发挥重要作用。在三阴性乳腺癌中，肿瘤浸润淋巴细胞表现出与组织驻留记忆T细胞（tissue-resident memory T cells,TRM）相关的分子表型和免疫功能特征，包括组织特异性归巢分子和免疫衰竭标志物的表达。高水平TRM与三阴性乳腺癌患者更好的预后相关，表明TRM类似于肿瘤浸润淋巴细胞，可能有助于抗肿瘤反应。全文重点讨论CD8+TRM的特征及临床意义，以及靶向这些细胞以提高三阴性乳腺癌患者免疫治疗方法成功率的潜在途径。     

干细胞样CD8+T细胞在抗肿瘤免疫治疗中的地位与演进效应

以抗细胞程序性死亡-1/细胞程序性死亡-配体1(programmed cell death-1/programmed cell death-ligand 1,PD-1/PD-L1)为代表的免疫检查点抑制剂(immune checkpoint inhibitors,ICIs)治疗显现了CD8⁺T细胞在治疗和可能治愈恶性肿瘤方面的潜力。但仅约20%的患者对ICIs治疗获益,因此阐明CD8⁺T细胞在免疫微环境中的有效抗肿瘤功能,及其分子和空间的决定因素尤为重要。具有自我更新、增殖分化和杀伤肿瘤细胞能力的干细胞样CD8⁺T细胞亚群,在介导抗肿瘤免疫效应方面扮演极为重要的角色。本文就干细胞样CD8⁺T细胞在抗肿瘤免疫循环中的地位与演进效应进行综述。     

调节性T细胞的分子靶向作用与肿瘤免疫治疗

调节性T细胞(Treg)具有免疫抑制功能,可通过在细胞表面表达细胞毒性T淋巴细胞相关抗原、穿孔素-颗粒酶介导的细胞毒作用、分泌细胞因子如白细胞介素-10(IL-10)、转化生长因子-β(TGF-β)等途径实现免疫抑制.采用抗体、疫苗和化学药物能够实现对FOXP3+CD25+CD4+调节性T细胞的靶向作用,使调节性T细胞在各种肿瘤患者外周血及肿瘤组织中的表达水平下调,降低其抑制免疫的功能,增强肿瘤免疫疗法的疗效.     

Anti-CD40-induced inflammatory E-cadherin+ dendritic cells enhance T cell responses and antitumour immunity in murine Lewis lung carcinoma

Background

Agonistic CD40 antibodies have been demonstrated to activate antigen-presenting cells (APCs) and enhance antitumour T cell responses, thereby providing a new therapeutic option in cancer immunotherapy. In agonistic CD40 antibody-mediated inflammatory responses, a novel subset of E-cadherin + dendritic cells (DCs) has been identified, and little is known about the role of these DCs in tumour immunity. This study investigated the effect of anti-CD40-mediated inflammatory E-cadherin + DCs in murine Lewis lung carcinoma (LLC).

Methods

The phenotype and characteristics of anti-CD40-mediated inflammatory E-cadherin + DCs isolated from the anti-CD40 model were assessed in vitro. The antitumour activity of E-cadherin + DCs were evaluated in vivo by promoting the differentiation of effector CD4+ T cells, CEA-specific CD8+ T cells and CD103+ CD8+ T cells and assessing their resistance to tumour challenge, including variations in tumour volume and survival curves.

Results

Here, we demonstrated that anti-CD40-mediated E-cadherin + inflammatory DCs accumulate in the lungs of Rag1 KO mice and were able to stimulate naïve CD4+ T cells to induce Th1 and Th17 cell differentiation and polarisation and to inhibit regulatory T cell and Th2 responses. Importantly, with the adoptive transfer of E-cadherin + DCs into the Lewis lung cancer model, the inflammatory DCs increased the Th1 and Th17 cell responses and reduced the Treg cell and Th2 responses. Interestingly, following the injection of inflammatory E-cadherin + DCs, the CD103+ CD8+ T cell and CEA-specific CD8+ T cell responses increased and exhibited potent antitumour immunity.

Conclusions

These findings indicate that anti-CD40-induced E-cadherin + DCs enhance T cell responses and antitumour activity in non-small cell lung cancer (NSCLC)-bearing mice and may be used to enhance the efficacy of DC-based peptide vaccines against NSCLC.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-015-0126-9) contains supplementary material, which is available to authorized users.     

癌相关CD8+记忆T细胞在过继免疫治疗中的应用

针对癌症患者的过继免疫治疗是临床肿瘤治疗研究中的热点话题。癌症患者体内天然存在着能够对恶性肿瘤细胞进行识别、攻击和杀伤的癌相关CD8+记忆T细胞,它们具有对少量肿瘤细胞产生快速免疫应答和持续长期发挥抗癌作用的优点。癌相关CD8+记忆T细胞主要存在于骨髓中,如将骨髓中的这部分T细胞分离出来,并以特定手段激活并回输体内,将可发挥强大的免疫治疗作用。为了帮助临床癌症治疗研究者们更加清晰地认识癌相关CD8+记忆T细胞的生物学特性、肿瘤杀伤能力和临床治疗效果,并妥善处理实际应用过程中遇到的各种问题,本文对近年有关癌相关CD8+记忆T细胞在肿瘤免疫治疗中应用的研究进展加以介绍。     

Tumor-induced changes in the phenotype of blood-derived and tumor-associated T cells of early stage breast cancer patients

Tumor‐induced immune suppression has mainly been studied in patients with advanced cancer. Despite the fact that they are most likely to benefit from immunotherapy, patients with early stage cancers were under‐represented in these studies. We analyzed blood and tumor‐derived T cells from patients with stage 1 (n = 20), stage 2 (n = 23) or stage 3 (n = 1) breast cancer and found that, even early stage tumors induced T cell differentiation. Breast cancer patients had significantly more circulating CD8+ memory and fewer CD8+ naïve T cells than healthy controls (n = 10). Up‐regulation of CD69 and PD1 on cancer patient T cells suggests previous activation, and increased expression of the chemokine receptors CCR5 and CXCR3 on CD8+ T cells indicates that their homing capacity differs from that of healthy individuals. Comparison of blood‐derived and tumor‐associated T cells from patients with different metastatic status and tumor grades revealed that tumor progression and aggressiveness seem to favor the expansion of memory T cells over naive T cells. We have previously shown that immunosuppression in this patient population is stronger in the tumor than in the blood. Here, we report signs of exhaustion, such as loss of CD28, on tumor‐associated as compared to blood‐derived CD8+ T cells, despite the fact that tumor‐associated T cells are predominantly effector memory cells and express high levels of CD69. The finding that the presence of a tumor potentially induces immunosenescence early during tumorigenesis indicates that efficient immunotherapy might be difficult even in patients with early stage cancer due to T cell exhaustion and tolerance.     

Identification of HLA-A3-restricted CD8+ T cell epitopes derived from mammaglobin-A,a tumor-associated antigen of human breast cancer

Mammaglobin-A is highly overexpressed in breast cancer cell lines and primary breast tumors. This pattern of expression is restricted to mammary epithelium and metastatic breast tumors. Thus, mammaglobin-A-specific T cell immune responses may provide an important approach for the design of breast cancer-specific immunotherapy. The purpose of our study was to define the T cell-mediated immune response to mammaglobin-A. We determined that the frequency of mammaglobin-A-reactive CD8+ and CD4+ T cells in breast cancer patients is significantly higher than that observed in healthy female controls using limiting dilution analyses (p = 0.026 and p = 0.02, respectively). We identified 8 mammaglobin-A-derived 9-mer peptides with the highest binding affinity for the HLA-A3 molecule (Mam-A3.1-8) using a computer-assisted analysis of the mammaglobin-A protein sequence. Subsequently, we determined that CD8+ T cells from breast cancer patients reacted to peptides Mam-A3.1 (23-31, PLLENVISK), Mam-A3.3 (2-10, KLLMVLMLA), Mam-A3.4 (55-63, TTNAIDELK) and Mam-A3.8 (58-66, AIDELKECF) using an IFN-gamma enzyme-linked immunospot assay. A CD8+ T cell line generated in vitro against HLA-A*0301-transfected TAP-deficient T2 cells loaded with these peptides showed significant cytotoxic activity against the Mam-A3.1 peptide. This CD8+ T cell line showed a significant HLA-A3-restricted cytotoxic activity against mammaglobin-A-positive but not mammaglobin-A-negative breast cancer cells. In summary, our study identified four HLA-A3-restricted mammaglobin-A-derived epitopes naturally expressed by breast cancer cells, indicating the immunotherapeutic potential of this novel antigen for the treatment and prevention of breast cancer.     

CD276 suppresses CAR-T cell function by promoting tumor cell glycolysis in esophageal squamous cell carcinoma

BackgroundAs an immune checkpoint that suppresses antitumor immunity, CD276 is a potential therapeutic target for cancer immunotherapy. However, the role of CD276 in esophageal squamous cell carcinoma (ESCC) has not been thoroughly examined. A greater understanding of the regulatory mechanism of CD276 may improve the clinical response and efficacy of cancer immunotherapy.MethodsThe expression of CD276 was measured by qRT-PCR, IHC and flow cytometry analysis. T cell infiltration in ESCC was measured by qRT-PCR and immunofluorescence analysis. The regulation function of CD276 in glucose metabolism was examined by metabolism assays, western blotting and small molecule inhibitors. Transfection was used for gene editing. The oncogenic function of CD276 was examined in vivo by CAR-T cell therapy model.ResultsBased on our findings, CD276 regulated the expression of the PKM2 gene in ESCC. Overexpression of CD276 induced the phosphorylation of PKM2 by the STAT3 signalling pathway to promote glucose metabolism in tumors. The accumulation of lactic acid in the tumor microenvironment has been reported to regulate the immune cells, particularly CD8+ T cells. We further analyzed the effect of CD276 on the function of T cells. Chimeric antigen receptor T cells (CAR-T) targeting human epidermal growth factor receptor 2 (HER2) were used as effector cells to detect the effect of CD276 on immunotherapy. The therapeutic effects of CAR-T cells were markedly limited by CD276 overexpression.ConclusionsOur results are the first to show that tumor-derived CD276 supports disease progression. Overexpression of CD276 promoted glucose metabolism in tumor and inhibited the function of CD8+ T cells. Therefore, strategies targeting CD276 might improve the response to cancer immunotherapy of ESCC patients.     

Cytotoxic T lymphocytes: role in immunosurveillance and in immunotherapy

Experiments in mice and recent human clinical studies have clearly shown the contribution of CD8+ T lymphocyte in the control of tumor development. CD8+ T lymphocytes are a constitutive component of the immune response during the development of cancer. In murine models, the efficiency of various cancer vaccines mainly depends on their ability to induce CD8+ T lymphocytes. Clinical responses in immunotherapy treated cancer patients have been associated with the presence of antitumor specific CD8+ T lymphocytes. In spontaneous regressive melanomas, intratumor antigen specific CD8+ cytotoxic T cells were expanded suggesting their involvement in the tumor shrinkage. Administration of antitumor specific cytotoxic T clones in mice resulted in antitumor responses which directly demonstrated the therapeutic efficiency of these cells. However, in most cases during cancer progression, the presence of antitumor CD8 T lymphocyte is not associated with clinical responses. Intrinsic functional abnormalities of these cells or a defect of CD8+ T cell migration to the tumor may in part explain their failure to inhibit tumor development. On the other hand, tumors also develop immune escape mechanisms (down modulation of tumor antigens, secretion of immunosuppressive factors, expression of anti-apoptotic molecules by the tumors, or pro-apoptotic factors inducing T cell death) to resist to the CD8+ T cell attack. To circumvent these tumor escape mechanisms, efficient cancer vaccines will have to recruit CD8+ T cells associated with other immune effectors.     

Identification of promiscuous HPV16‐derived T helper cell epitopes for therapeutic HPV vaccine design

Cervical carcinoma and several other human papillomavirus (HPV)‐induced malignancies are a global public health problem, thus novel treatment modalities are urgently needed. Immunotherapy is an attractive option for treatment of HPV infection and HPV‐mediated premalignant and malignant lesions. However, previous approaches—focusing on the induction of cytotoxic CD8+ T cells (CTLs)—have as yet not yielded clinical successes. Since CD4+ T cells have been shown to be crucial for the induction and maintenance of CTL responses, and more recently to be also important for direct anti‐tumor immunity, human leukocyte antigen (HLA) class II‐restricted epitopes are intensively investigated to improve the efficacy of peptide‐based HPV immunotherapy. We here present an approach to identify promiscuous HPV16‐derived CD4+ T helper epitopes, which are capable of inducing T cell immunity in a large proportion of the population. To this end, we combined HLA class II epitope prediction servers with in vitro immunological evaluation to identify HPV16 E2‐, E5‐, E6‐, and E7‐derived CD4+ T cell epitopes. Candidate selected HPV16‐derived epitopes were found to be restricted by up to nine HLA‐DR molecules. Furthermore, they were found to induce frequent and robust HPV16 peptide‐specific Th1 responses in healthy donors, as monitored by interferon (IFN)‐γ ELISPOT and cytokine secretion assays. Moreover, these selected peptides also induced specific IFN‐γ T cell responses in blood from HPV16+ CIN2/3 and cervical carcinoma patients. We thus conclude that the identified T helper epitopes are valuable candidates for the development of a comprehensive therapeutic HPV vaccine.     

Circulating and tumor-infiltrating Tim-3 in patients with colorectal cancer

T-cell exhaustion represents a progressive loss of T-cell function. The inhibitory receptor PD-1 is known to negatively regulate CD8⁺ T cell responses directed against tumor antigen, but the blockades of PD-1 pathway didn''t show the objective responses in patients with colorectal cancer (CRC). Thus, further exploring the molecular mechanism responsible for inducing T-cell dysfunction in CRC patients may reveal effective strategies for immune therapy. This study aims to characterize co-inhibitory receptors on T cells in CRC patients to identify novel targets for immunotherapy. In this study, peripheral blood samples from 20 healthy controls and 54 consented CRC patients, and tumor and matched paraneoplastic tissues from 7 patients with advanced CRC, subjected to multicolor flow cytometric analysis of the expression of PD-1 and Tim-3 receptors on CD8⁺ T cells. It was found that CRC patients presented with significantly higher levels of circulating Tim-3⁺PD-1⁺CD8⁺ T cells compared to the healthy controls (medians of 3.12% and 1.99%, respectively, p = 0.0403). A similar increase of Tim-3⁺PD-1⁺CD8⁺ T cells was also observed in the tumor tissues compared to paraneoplastic tussues. Tim-3⁺PD-1⁺CD8⁺ T cells in tumor tissues produced even less cytokine than that in paraneoplastic tissues. Functional ex vivo experiments showed that Tim-3⁺PD-1⁺CD8⁺ T cells produced significantly less IFN-γ than Tim-3⁻PD-1⁻CD8⁺ T cells, followed by Tim-3⁺PD-1⁻CD8⁺ T cells, and Tim-3⁻PD-1⁺CD8⁺ T cells, indicating a stronger inhibition of IFN-γ production of Tim-3⁺CD8⁺ T cells. It is also found in this study that Tim-3⁺PD-1⁺CD8⁺ T cell increase in circulation was correlated with clinical cancer stage but not histologic grade and serum concentrations of cancer biomarker CEA. Our results indicate that upregulation of the inhibitory receptor Tim-3 may restrict T cell responses in CRC patients, and therefore blockage of Tim-3 and thus restoring T cell responses may be a potential therapeutic approach for CRC patients.     

Immune landscape of vulvar cancer patients treated with surgery and adjuvant radiotherapy revealed restricted T cell functionality and increased IL-17 expression associated with cancer relapse

For vulvar cancers, radiotherapy is targeting cancer cells, but also affects the host immune system. As this may affect treatment outcome, in this prospective study, we characterized the individual T cell immune milieu induced by surgery and adjuvant radio +/− chemotherapy (aRT) systemically in the blood of vulvar cancer patients and found increased frequencies of Interleukin (IL)-17-producing CD4⁺ and CD8⁺ T cells after aRT while frequencies of Th1 and perforin-producing CD8⁺ killer cells were strongly diminished. Phenotypic characterization revealed enhanced expression of the ectonucleotidase CD39 on Th17 and Tc17 cells as well as CD8⁺ perforin⁺ cells after aRT. Furthermore, the aRT cohort exhibited increased proportions of Programmed Cell Death Protein (PD-1) expressing cells among Th1 and CD8⁺ perforin⁺ cells, but not among Th17 and Tc17 cells. High post-therapeutic levels of Th17 and Tc17 cells and low proportions of Th1 and CD8⁺ perforin⁺ cells expressing PD-1 was associated with reduced recurrence free survival on follow-up. In conclusion, our study defines individual therapy-induced changes in the cellular immune milieu of patients and their association with cancer relapse. Our results may help to explain differences in the individual courses of disease of vulvar cancer patients and suggest PD-1 and IL-17 as targets for immunotherapy in vulvar cancer.     

T cell adhesion and cytolysis of pancreatic cancer cells: a role for E-cadherin in immunotherapy?

Pancreatic cancer is an aggressive and potent disease, which is largely resistant to conventional forms of treatment. However, the discovery of antigens associated with pancreatic cancer cells has recently suggested the possibility that immunotherapy might become a specific and effective therapeutic option. T cells within many epithelia, including those of the pancreas, are known to express the alphaEbeta7-integrin adhesion molecule, CD103. The only characterised ligand for CD103 is E-cadherin, an epithelial adhesion molecule which exhibits reduced expression in pancreatic cancer. In our study, CD103 was found to be expressed only by activated T cells following exposure to tumour necrosis factor beta 1, a factor produced by many cancer cells. Significantly, the expression of this integrin was restricted mainly to class I major histocompatibility complex-restricted CD8+ T cells. The human pancreatic cancer cell line Panc-1 was transfected with human E-cadherin in order to generate E-cadherin negative (wild type) and positive (transfected) sub-lines. Using a sensitive flow cytometric adhesion assay it was found that the expression of both CD103 (on T cells) and E-cadherin (on cancer cells) was essential for efficient adhesion of activated T cells to pancreatic cancer cells. This adhesion process was inhibited by the addition of antibodies specific for CD103, thereby demonstrating the importance of the CD103-->E-cadherin interaction for T-cell adhesion. Using a 51Cr-release cytotoxicity assay it was found that CD103 expressing T cells lysed E-cadherin expressing Panc-1 target cells following T cell receptor stimulation; addition of antibodies specific for CD103 significantly reduced this lysis. Furthermore, absence of either CD103 from the T cells or E-cadherin expression from the cancer cells resulted in a significant reduction in cancer cell lysis. Therefore, potentially antigenic pancreatic cancer cells could evade a local anti-cancer immune response in vivo as a consequence of their loss of E-cadherin expression; this phenotypic change may also favour metastasis by reducing homotypic adhesion between adjacent cancer cells. We conclude that effective immunotherapy is likely to require upregulation of E-cadherin expression by pancreatic cancer cells or the development of cytotoxic immune cells that are less dependent on this adhesion molecule for efficient effecter function.