Distinct role of CD8 cells and CD4 cells in antitumor immunity triggered by cell apoptosis using a Herpes simplex virus thymidine kinase/ganciclovir system

Immune cells can recognize tumor-associated antigens released from dead tumor cells, which elicit immune responses, potentially resulting in tumor regression. Tumor cell death induced by chemotherapy has also been reported to activate immunity. However, various studies have reported drug-induced immunosuppression or suppression of inflammation by apoptotic cells. Thus, this study aimed to investigate whether apoptotic tumor cells trigger antitumor immunity independent of anticancer treatment. Local immune responses were evaluated after direct induction of tumor cell apoptosis using a Herpes simplex virus thymidine kinase/ganciclovir (HSV-tk/GCV) system. The inflammatory response was significantly altered at the tumor site after apoptosis induction. The expression of cytokines and molecules that activate and suppress inflammation simultaneously increased. The HSV-tk/GCV-induced tumor cell apoptosis resulted in tumor growth suppression and promoted T lymphocyte infiltration into tumors. Therefore, the role of T cells after inducing tumor cell death was explored. CD8 T cell depletion abrogated the antitumor efficacy of apoptosis induction, indicating that tumor regression was mainly dependent on CD8 T cells. Furthermore, CD4 T cell depletion inhibited tumor growth, suggesting the potential role of CD4 T cells in suppressive tumor immunity. Tumor tissues were evaluated after tumor cell apoptosis and CD4 T cell depletion to elucidate this immunological mechanism. Foxp3 and CTLA4, regulatory T-cell markers, decreased. Furthermore, arginase 1, an immune-suppressive mediator induced by myeloid cells, was significantly downregulated. These findings indicate that tumors accelerate CD8 T cell-dependent antitumor immunity and CD4 T cell-mediated suppressive immunity. These findings could be a therapeutic target for immunotherapy in combination with cytotoxic chemotherapy.     

Tumor-induced expansion of regulatory T cells by conversion of CD4+CD25- lymphocytes is thymus and proliferation independent

The CD25- and CD25+ CD4 T-lymphocyte compartments are tightly regulated. We show here that tumors break such balance, increasing the number of CD4+CD25+ T cells in draining lymph node and spleen but not contralateral node of tumor-bearing mice. Tumor injection in thymectomized and CD25-depleted mice shows that CD4+CD25+ T-cell expansion occurs even in the absence of the thymus and independently from proliferation of preexisting CD25+ T cells. These newly generated cells are bona fide regulatory T cells (T reg) in terms of Foxp3 expression and suppression of CD3-stimulated or allogeneic effector cell proliferation. Transfer of congenic Thy1.1 CD4+CD25- T cells, from mice treated or not with vinblastine, into tumor-bearing or tumor-free mice and analysis of recovered donor lymphocytes indicate that conversion is the main mechanism for acquiring the expression of CD25 and Foxp3 through a process that does not require proliferation. Although conversion of CD4+CD25- T cells for generation of T regs has been described as a natural process that maintains peripheral T-reg population, this process is used by the tumor for immune escape. The prompt recovery of T regs from monoclonal antibody-mediated CD25 depletion in tumor-bearing mice suggests attempts able to inactivate rather than deplete them when treating existing tumors.     

Regulatory T cells in tumor immunity

Recent studies have revealed that Foxp3⁺CD25⁺CD4⁺ regulatory T cells (Tregs), which are physiologically engaged in the maintenance of immunological self‐tolerance, play critical roles for the control of antitumor immune responses. For example, a large number of Foxp3⁺Tregs infiltrate into tumors, and systemic removal of Foxp3⁺Tregs enhances natural as well as vaccine‐induced antitumor T‐cell responses. Tregs are recruited to tumor tissues via chemokines, such as CCL22 binding to CCR4 expressed by Tregs. They appear to expand and become activated in tumor tissues and in the draining lymph nodes by recognizing tumor‐associated antigens as well as normal self‐antigen expressed by tumor cells. These results indicate that cancer vaccines targeting tumor‐associated self‐antigens may potentially expand/activate Tregs and hamper effective antitumor immune responses, and that tumor immunity can therefore be enhanced by depleting Tregs, attenuating Treg suppressive function, or rendering effector T cells refractory to Treg‐mediated suppression. Recent attempts have indeed demonstrated that combinations of monoclonal antibodies capable of modulating Treg functions synergistically enhance antitumor activity and are more effective than a single monoclonal antibody therapy. Combination therapy targeting a variety of molecules expressed in antigen‐presenting cells, effector T cells and Tregs is envisaged to be a promising anticancer immunotherapy.     

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.     

Adoptive cell therapy for lymphoma with CD4 T cells depleted of CD137-expressing regulatory T cells

Adoptive immunotherapy with antitumor T cells is a promising novel approach for the treatment of cancer. However, T-cell therapy may be limited by the cotransfer of regulatory T cells (T(reg)). Here, we explored this hypothesis by using 2 cell surface markers, CD44 and CD137, to isolate antitumor CD4 T cells while excluding T(regs). In a murine model of B-cell lymphoma, only CD137(neg)CD44(hi) CD4 T cells infiltrated tumor sites and provided protection. Conversely, the population of CD137(pos)CD44hi CD4 T cells consisted primarily of activated T(regs). Notably, this CD137(pos) T(reg) population persisted following adoptive transfer and maintained expression of FoxP3 as well as CD137. Moreover, in vitro these CD137(pos) cells suppressed the proliferation of effector cells in a contact-dependent manner, and in vivo adding the CD137(pos)CD44(hi) CD4 cells to CD137(neg)CD44(hi) CD4 cells suppressed the antitumor immune response. Thus, CD137 expression on CD4 T cells defined a population of activated T(regs) that greatly limited antitumor immune responses. Consistent with observations in the murine model, human lymphoma biopsies also contained a population of CD137(pos) CD4 T cells that were predominantly CD25(pos)FoxP3(pos) T(regs). In conclusion, our findings identify 2 surface markers that can be used to facilitate the enrichment of antitumor CD4 T cells while depleting an inhibitory T(reg) population.     

L1CAM promotes enrichment of immunosuppressive T cells in human pancreatic cancer correlating with malignant progression

Regulatory T cell (T‐reg) enrichment in the tumor microenvironment is regarded as an important mechanism of tumor immune escape. Hence, the presence of T‐regs in highly malignant pancreatic ductal adenocarcinoma (PDAC) is correlated with short survival. Likewise, the adhesion molecule L1CAM is upregulated during PDAC progression in the pancreatic ductal epithelium also being associated with poor prognosis. To investigate whether L1CAM contributes to enrichment of T‐regs in PDAC, human CD4+CD25+CD127−CD49d− T‐regs and CD4+CD25− T‐effector cells (T‐effs) were isolated by magnetic bead separation from blood of healthy donors. Their phenotype and functional behavior were analyzed in dependence on human premalignant (H6c7) or malignant (Panc1) pancreatic ductal epithelial cells, either exhibiting or lacking L1CAM expression. T cells derived from blood and tumors of PDAC patients were analyzed by flow cytometry and findings were correlated with clinical parameters. Predominantly T‐regs but not T‐effs showed an increased migration on L1CAM expressing H6c7 and Panc1 cells. Whereas proliferation of T‐regs did not change in the presence of L1CAM, T‐effs proliferated less, exhibited a decreased CD25 expression and an increased expression of CD69. Moreover, these T‐effs exhibited a regulatory phenotype as they inhibited proliferation of autologous T cells. Accordingly, CD4+CD25−CD69+ T cells were highly abundant in PDAC tissues compared to blood being associated with nodal invasion and higher grading in PDAC patients. Overall, these data point to an important role of L1CAM in the enrichment of immunosuppressive T cells in particular of a CD4+CD25−CD69+‐phenotype in PDAC providing a novel mechanism of tumor immune escape which contributes to tumor progression.     

AnnexinA5 promote glioma cell invasion and migration via the PI3K/Akt/NF-κB signaling pathway

Malignant glioma (MG), the most common primary brain tumor in adults, is extremely aggressive and uniformly fatal. Several treatment strategies have shown significant preclinical promise in murine models of glioma; however, none have produced meaningful clinical responses in human patients. We hypothesize that introduction of an additional preclinical animal model better approximating the complexity of human MG, particularly in interactions with host immune responses, will bridge the existing gap between these two stages of testing. Here, we characterize the immunologic landscape and gene expression profiles of spontaneous canine glioma and evaluate its potential for serving as such a translational model. RNA in situ hybridization, flowcytometry, and RNA sequencing were used to evaluate immune cell presence and gene expression in healthy and glioma-bearing canines. Similar to human MGs, canine gliomas demonstrated increased intratumoral immune cell infiltration (CD4+, CD8+ and CD4+Foxp3+ T cells). The peripheral blood of glioma-bearing dogs also contained a relatively greater proportion of CD4+Foxp3+ regulatory T cells and plasmacytoid dendritic cells. Tumors were strongly positive for PD-L1 expression and glioma-bearing animals also possessed a greater proportion of immune cells expressing the immune checkpoint receptors CTLA-4 and PD-1. Analysis of differentially expressed genes in our canine populations revealed several genetic changes paralleling those known to occur in human disease. Naturally occurring canine glioma has many characteristics closely resembling human disease, particularly with respect to genetic dysregulation and host immune responses to tumors, supporting its use as a translational model in the preclinical testing of prospective anti-glioma therapies proven successful in murine studies.     

负性协同刺激分子B7-H4在非小细胞肺癌组织中的表达及其临床意义

目的：探讨负性协同刺激分子B7H4在原发性非小细胞肺癌（nonsmall cell lung cancer,NSCLC）组织中的表达及其与NSCLC临床病理特征间的关系。方法：选取南通大学第三附属医院胸外科2008年1月至2009年4月手术切除并经病理证实的NSCLC标本52例。免疫组织化学法检测NSCLC组织中B7H4分子的表达及CD3+T细胞浸润程度,分析B7H4表达水平与NSCLC组织中CD3+T细胞浸润、临床病理特征间的关系。结果：52例NSCLC组织中B7H4表达阳性率为4808%（25/52）,正常肺组织不表达或较少表达B7H4,差异具有统计学意义（P<0.05）。B7H4表达水平与NSCLC临床分期和淋巴结转移呈正相关（P<0.05）,与CD3+T淋巴细胞浸润程度呈负相关（P<0.05）,与其他临床病理参数无关（P>005）。结论：负性协同刺激分子B7H4在NSCLC发病过程中可能起重要的作用,其阳性表达与NSCLC临床分期及淋巴结转移密切相关,B7H4为NSCLC的诊断及治疗提供参考依据。     

Systemic CTLA-4 blockade ameliorates glioma-induced changes to the CD4+ T cell compartment without affecting regulatory T-cell function.

PURPOSE: Patients with malignant glioma suffer global compromise of their cellular immunity, characterized by dramatic reductions in CD4(+) T cell numbers and function. We have previously shown that increased regulatory T cell (T(reg)) fractions in these patients explain T-cell functional deficits. Our murine glioma model recapitulates these findings. Here, we investigate the effects of systemic CTLA-4 blockade in this model. EXPERIMENTAL DESIGN: A monoclonal antibody (9H10) to CTLA-4 was employed against well-established glioma. Survival and risks for experimental allergic encephalomyelitis were assessed, as were CD4(+) T cell numbers and function in the peripheral blood, spleen, and cervical lymph nodes. The specific capacities for anti-CTLA-4 to modify the functions of regulatory versus CD4(+)CD25(-) responder T cells were evaluated. RESULTS: CTLA-4 blockade confers long-term survival in 80% of treated mice, without eliciting experimental allergic encephalomyelitis. Changes to the CD4 compartment were reversed, as anti-CTLA-4 reestablishes normal CD4 counts and abrogates increases in CD4(+)CD25(+)Foxp3(+)GITR(+) regulatory T cell fraction observed in tumor-bearing mice. CD4(+) T-cell proliferative capacity is restored and the cervical lymph node antitumor response is enhanced. Treatment benefits are bestowed exclusively on the CD4(+)CD25(-) T cell population and not T(regs), as CD4(+)CD25(-) T cells from treated mice show improved proliferative responses and resistance to T(reg)-mediated suppression, whereas T(regs) from the same mice remain anergic and exhibit no restriction of their suppressive capacity. CONCLUSIONS: CTLA-4 blockade is a rational means of reversing glioma-induced changes to the CD4 compartment and enhancing antitumor immunity. These benefits were attained through the conferment of resistance to T(reg)-mediated suppression, and not through direct effects on T(regs).     

Expression of Fas/FasL in CD8+ T and CD3+ Foxp3+ Treg Cells - Relationship with Apoptosis of Circulating CD8+ T Cells in Hepatocellular Carcinoma Patients

Aims: Dysfunction of the host immune system in cancer patients can be due to a number of factors, includinglymphocyte apoptosis. Several studies showed that Foxp3+T cells take part in inducing this process by expressingFasL in tumor patients. However, the relationship between apoptosis, CD8+T cells and Foxp3+T cells in HCCpatients is still unclear. The present study was designed to investigate the correlation between apoptosis levelsand Fas/FasL expression in CD8+T lymphocytes and Foxp3+T cells in patients with HCC. Methods: CD8+T cellsand CD3+Foxp3+T cells were tested from peripheral blood of HCC patients and normal controls and subjectedto multicolor flow cytometry. The expression of an apoptosis marker (annexin V) and the death receptor Fas inCD8+T cells and FasL in CD3+Foxp3+T cells were evaluated. Serum TGF-β1 levels in patients with HCC weremeasured by enzyme-linked immunosorbent assay. The relationship between apoptosis and Fas expression, aswell as FasL expression in CD3+Foxp3+T cells was then evaluated. Results: The frequency of CD8+T cells bindingannexin V and Fas expression in CD8+T cells, were all higher in HCC patients than normal controls and theproportion of apoptotic CD8+T cells correlated with their Fas expression. Serum TGF-β1 levels correlated inverselywith CD3+Foxp3+T cells. Conclusions: Fas/FasL interactions might lead to excessive turnover of CD8+T cellsand reduce anti-tumor immune responses in patients with HCC. Further investigations of apoptosis inductionin Fas+CD8+T cells in vitro are required.     

肝细胞性肝癌组织浸润淋巴细胞表型与分布研究

目的:肝细胞性肝癌组织浸润淋巴细胞与外周血T 细胞表型可能与肿瘤进展及预后相关,本研究检测肝癌患者组织及外周血T 细胞表型与分布,分析淋巴细胞表型变化与预后的关系。方法:分析2007年10月至12月中山医院147 例肝癌及癌旁组织浸润淋巴细胞表型（T 细胞或B 细胞表面标志物:CD3、CD8、CD4、CD20、CD19、Foxp 3）,表型与临床病理特征及预后的关系;检测26例肝癌外周血CD3、CD8、CD4 +T细胞数量并其比例变化。结果:癌巢内肿瘤浸润细胞明显少于癌周组织（P < 0.01）,癌周淋巴细胞主要分布于癌旁正常肝组织、汇管区,其与患者肝炎病史及肝硬化相关,表型以CD3 +T细胞为主,其中又以CD8 + 细胞毒性T 细胞为主;CD4 染色在多数病例为阴性,Foxp 3 仅在个别病例（15/ 109）呈阳性。肿瘤浸润淋巴细胞B 细胞标志CD20、CD19均为阴性。肿瘤组织内CD8 +T细胞浸润数量与预后正相关,而癌周浸润淋巴细胞数目与患者转移及复发无显著关系。结论:肝癌肿瘤浸润细胞在癌巢内明显少于癌周组织,肿瘤及癌周浸润细胞以CD8 + 细胞毒性T 细胞为主。肿瘤组织内CD8 +T细胞浸润数量与预后相关,而癌周浸润淋巴细胞数量与患者转移及复发无显著关系。      

CD4+CD25+调节性T细胞在Lewis肺癌移植鼠中的检测及临床意义

目的:研究Lewis肺癌移植鼠胸腺与脾脏CD4 CD25 调节性T细胞数量及其相关基因Foxp3 mR-NA的表达特点,探讨CD4 CD25 调节性T细胞在诱导肿瘤免疫耐受中的作用。方法:将传代培养的Lewis肺癌细胞接种于C57BL/6小鼠右腋皮下,建立Lewis肺癌模型。观测成瘤率、平均瘤重、肿瘤体积动态变化;采用MTT法检测胸腺及脾脏T淋巴细胞增殖功能;采用流式细胞术检测胸腺及脾脏CD4 CD25 调节性T细胞数量变化;采用半定量RT-PCR方法检测肺癌小鼠胸腺与脾脏Foxp3 mRNA表达水平。结果:Lewis肺癌的移植成瘤率为100%,平均瘤重(3.34±1.79)g;胸腺T淋巴细胞增殖功能略有降低,但降低不显著(P>0.05),而脾脏T淋巴细胞增殖功能明显降低(P<0.05);胸腺及脾脏CD4 CD25 调节性T细胞数量均明显升高(P<0.05);Foxp3 mRNA在肺癌模型组的胸腺表达明显增高(P<0.05),在肺癌模型组脾脏Foxp3 mRNA表达中也略有增加,但增高不显著(P>0.05)。结论:CD4 CD25 调节性T细胞可能在肿瘤免疫耐受中发挥重要作用。     

乳腺癌髓系来源抑制细胞中IDO表达与调节性T细胞相关性及其临床意义的研究

  目的  研究不同期别乳腺癌组织中CD33+髓系来源抑制细胞(MDSCs)和Foxp3+调节性T细胞(Tregs)的分布情况, 探讨MDSCs中吲哚胺2, 3-双加氧酶(IDO)表达与Tregs分布关系及其临床意义。   方法  收集天津医科大学附属肿瘤医院2005年1月至2007年1月手术患者的乳腺癌石蜡切片50例, 采用免疫组织化学单染方法对肿瘤局部CD33+MDSCs和Foxp3+Tregs分布和比例进行检测; 采用免疫组织化学双染方法检测肿瘤原位浸润MDSCs中IDO的表达情况; 分析MDSCs中IDO表达与Tregs分布、比例及其他临床病理资料之间的相关性。   结果  Foxp3+Tregs和CD33+MDSCs细胞在乳腺癌组织中呈散在性分布。MDSCs中IDO表达水平与腋窝淋巴结转移密切相关(P < 0.05)。Foxp3+Tregs高表达组中MDSCs中IDO表达水平显著高于Foxp3+Tregs低表达或不表达组(P < 0.05)。   结论  MDSCs中IDO过表达可能有利于Tregs的募集和乳腺癌的转移。      

Natural killer cells infiltrating human nonsmall-cell lung cancer are enriched in CD56 bright CD16(-) cells and display an impaired capability to kill tumor cells

BACKGROUND: Despite natural killer (NK) cells being originally identified and named because of their ability to kill tumor cells in vitro, only limited information is available on NK cells infiltrating malignant tumors, especially in humans. METHODS: NK cells infiltrating human nonsmall cell lung cancers (NSCLC) were analyzed with the aim of identifying their potential protective role in an antitumor immune response. Both relevant molecule expression and functions of NK cells infiltrating NSCLC were analyzed in comparison with autologous NK cells isolated from either peritumoral normal lung tissues or peripheral blood. RESULTS: The CD56 bright CD16(-) NK cell subset was consistently observed as being highly enriched in tumor infiltrate and displayed activation markers, including NKp44, CD69, and HLA-DR. Remarkably, the cytolytic potential of NK cells isolated from cancer tissues was lower than that of NK cells from peripheral blood or normal lung tissue, whereas no difference was observed regarding their capability of producing cytokines. With regard to their localization within tumor, NK cells were found in tumor stroma, whereas they were not in direct contact with cancer cells. CONCLUSIONS: For the first time NK cells infiltrating NSCLC have been characterized and it is shown that they are mainly capable of producing relevant cytokines rather than exerting direct cancer cell killing.     

Increased populations of regulatory T cells in peripheral blood of patients with hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide with a poor prognosis and one for which immunotherapy remains a viable option. Experimental tumor models have shown that regulatory T cells, a functionally unique subset of T cells, can suppress effective antitumor immune responses. This suppression might explain the poor outcome of some of the immunotherapy protocols currently being used. A better understanding of the role of regulatory T cells in HCC is important for design of future immunotherapy-based clinical protocols. We have studied regulatory T cells from 84 patients with HCC and 74 controls, including healthy donors, patients with chronic hepatitis B virus and hepatitis C virus infection and nonviral liver cirrhosis. Regulatory T cells were identified by fluorescence-activated cell sorting using a panel of antibodies and by real-time PCR analysis for Foxp3 expression. Functional studies were done to analyze their inhibitory role. Finally, regulatory T cells were analyzed in tumors and ascites from patients with HCC. Patients with HCC have increased numbers of CD4+CD25+ regulatory T cells in their peripheral blood, which express high levels of HLA-DR, GITR, and low or no CD45RA. These cells were anergic toward T-cell receptor stimulation and, when cocultured with activated CD4+CD25- cells, potently suppressed their proliferation and cytokine secretion. There were also high numbers of regulatory T cells in tumor-infiltrating lymphocytes of HCC patients comparable with the increase in their peripheral blood. Our data suggest that the increase in frequency of regulatory T cells might play a role in modulation of the immune response against HCC and could be important in design of immunotherapeutic approaches.