双歧杆菌脂磷壁酸对化疗荷瘤小鼠免疫功能的影响

目的探讨双歧杆菌脂磷壁酸对5-氟尿嘧啶（5-FU）化疗肝癌H22荷瘤小鼠免疫的影响及其作用机制。方法双歧杆菌脂磷壁酸处理5-Fu化疗的H纶荷瘤Balb／c小鼠,MTT法检测NK细胞和CTL细胞杀伤活性;采用流式细胞仪检测荷瘤小鼠脾细胞中T亚群比例;用RT-PCR和Western Not方法分别检测荷瘤小鼠肿瘤组织Foxp3和TIM-3mRNA及蛋白的表达变化。结果荷瘤小鼠脾细胞中CD4^＋ CD25^＋Tmg比例高,并存在Foxp3和TIM-3 mRNA及蛋白的高表达,经双歧杆菌LTA和5．Fu处理后CD4^＋CD25^＋Tmg比例下降,Foxp3和TIM-3mRNA及蛋白表达水平也均呈下调趋势,但5-FU单独处理后的荷瘤小鼠脾细胞中CD4^＋细胞比例也减少,NK细胞和CTL杀伤率均降低,而双歧杆菌LTA处理后CD4^＋细胞比例,NK细胞和CTL杀伤率却明显增加。二者联合处理也能增加CD^＋细胞比例及NK细胞和CTL杀伤率。结论双歧杆菌脂磷壁酸联合5-FU可通过增强NK细胞和CTL杀伤能力,同时抑制TIM-3／TIM-3L途径,降低CD4^＋CD25^＋Tmg的免疫抑制活性,增强机体细胞免疫来提高化疗抗肿瘤效果,减轻化疗副作用,增强宿主对化疗的耐受性,从而提高抗肿瘤作用。     

Caspase信号通路在双歧杆菌脂磷壁酸诱导结肠癌细胞凋亡中的作用

目的探讨Caspase信号通路在双歧杆菌脂磷壁酸（LTA）诱导结肠癌细胞凋亡中的作用。方法RT-PCR检测经双歧杆菌LTA处理后,结肠癌Lovo细胞中MyD88和FADD mRNA的表达变化;AnnexinV检测经Caspase通用抑制剂（Z-Val-Ala-Asp-FMK）预先处理后,双歧杆菌LTA诱导结肠癌Lovo细胞凋亡率的变化;荧光法检测经双歧杆菌LTA处理后,Lovo细胞中Caspase-8活性的变化。结果经双歧杆菌LTA处理后,Lovo细胞中MyD88的mRNA表达明显升高（P〈0．05）,而FADD信号分子的mRNA表达无明显变化;双歧杆菌LTA能够增强Lovo细胞中Caspase-8的活性（P〈0．05）,且其诱导Lovo细胞凋亡的作用能够被Caspase抑制剂所抑制（P〈0．05）。结论MyD88信号分子在双歧杆菌LTA诱导Lovo细胞凋亡中可能起着承接上游分子TLRs与下游信号分子FADD的作用;而Caspase信号通路可能是双歧杆菌LTA诱导结肠癌Lovo细胞凋亡的主要信号传导途径。     

生物肽SP对NK细胞NKG2D/NKG2A受体表达的影响

选择NK92-MI细胞为研究体系,研究SP对NK细胞的杀伤活性及功能性受体NKG2D/NKG2A表达的影响,以探讨SP对NK细胞功能的调节作用机制。采用MTT法测定NK92-MI细胞对K562细胞的杀伤活性;采用Real-Time PCR和流式细胞术检测NK92-MI细胞活化性受体NKG2D和抑制性受体NKG2A的基因表达和膜表达。10-14～10-8 mol/L的SP在体外可明显增强NK92-MI细胞的杀伤活性。该浓度范围的SP均可上调NKG2D/NKG2A的mRNA水平;10-14～10-8 mol/L的SP均上调NKG2D/NKG2A的膜表达,较低浓度（10-14 mol/L）的SP仅使NKG2D表达上调,而NKG2A表达无明显变化;SP刺激NKG2D膜表达增加的程度高于NKG2A。生物肽SP调节NK细胞功能性受体NKG2D/NKG2A的表达,可能是SP增强NK细胞杀伤活性的一种原因。     

双歧杆菌脂磷壁酸与5-氟尿嘧啶体内联用对肿瘤细胞凋亡的影响

目的研究双歧杆菌脂磷壁酸与5-氟尿嘧啶联用诱导H22荷瘤小鼠肿瘤细胞凋亡的作用机制。方法双歧杆菌脂磷壁酸联合5-FU处理H22荷瘤Balb/c小鼠,计算抑瘤率,观察小鼠生存期;采用Real time-PCR和Western blot方法分别检测荷瘤小鼠肿瘤组织Bcl-2、Bax和Caspase-3 mRNA及蛋白的表达变化。结果双歧杆菌脂磷壁酸联合5-FU应用,与单独5-FU处理组比较,不仅抑瘤率明显提高（P〈0.01）,且荷瘤小鼠存活时间明显延长（P〈0.01）,肿瘤组织Bcl-2表达下降,Bax和Caspase-3表达升高（P〈0.05）。结论双歧杆菌脂磷壁酸联合5-FU可通过上调Bax和Caspase-3,下调Bcl-2,促进肿瘤细胞凋亡,从而发挥协同抗肿瘤作用。     

双歧杆菌脂磷壁酸和总DNA对小鼠免疫功能的影响

目的比较双歧杆菌2种组分即双歧杆菌脂磷壁酸（LTA）和总DNA的免疫调节作用。方法分别提取和制备双歧杆菌LTA和总DNA。采用淋巴细胞转化法和溶血空斑法分别研究它们对小鼠细胞和体液免疫的调节作用。结果与对照组比较,双歧杆菌和总DNA对T细胞和B细胞都有明显的刺激作用（P〈0．05或P〈0．01）,但是LTA的作用更强（P〈0．01）。结论双歧杆菌细胞壁的LTA和细胞核的总DNA均具有免疫调节作用,但前者效能优于后者。     

5-氟尿嘧啶增强HeLa细胞对自然杀伤细胞敏感性研究

目的用5-氟尿嘧啶（5-fluorouracil,5-FU）处理HeLa细胞,检测其NKG2D配体MICA的表达及其对NK92细胞杀伤敏感性的变化。方法不同浓度的5-Fu处理HeLa细胞,在不同时间点用半定量PCR及流式细胞术检测HeLa细胞表面的NKG2D配体MICA在RNA及蛋白水平的表达变化情况,用MTT法检测NKG2D抗体封闭NK92细胞的NKG2D受体前后,NK92细胞对HeLa细胞的杀伤作用。结果不同浓度的5．Fu作用于HeLa细胞后,半定量RT—PCR结果显示MICA表达随5-Fu作用浓度增加逐渐增高。而且40μg／ml5．Fu作用于HeLa细胞后随着作用时间的延长（0、8、16、24h）MICA表达增加,流式细胞术检测结果表明,MICA表达的增加主要依赖于未凋亡细胞的MICA表达。在40μg／ml5-FU作用24h,效靶比为2．5：1,5：1,10：1,20：1时都检测到NK92细胞对HeLa细胞的杀伤增强,杀伤作用可部分被NKG2D抗体抑制。结论5-FU能够上调HeLa细胞表面NKG2D配体MICA的表达,增强HeLa细胞对NK92细胞的敏感性,提示化疗联合NK细胞免疫治疗宫颈癌可产生协同作用,提高治疗效果。     

Toll样受体在双歧杆菌脂磷壁酸诱导结肠癌细胞凋亡中的作用

目的探讨双歧杆菌脂磷壁酸（LTA）对Toll样受体（TLRs）表达的影响及其与诱导结肠癌细胞凋亡之间的关系。方法用AnnexinV检测在双歧杆菌LTA处理前后结肠癌Lovo细胞凋亡的变化;流式细胞术检测Lovo细胞表面TLRs的表达,并用相应的TLRs封闭抗体作用后,AnnexinV检测经双歧杆菌LTA诱导的Lovo细胞凋亡的变化。结果经双歧杆菌LTA处理后,结肠癌Lovo细胞发生了明显的凋亡,并有一定的时间和剂量依赖关系;结肠癌Lovo细胞有TLR受体的基础表达,经双歧杆菌LTA处理后,TLR2和TLR4在Lovo细胞上的表达增加,其中尤以TLR2增加更为明显;用相应的TLRs抗体封闭作用后,双歧杆菌LTA诱导Lovo细胞凋亡的能力下降。结论双歧杆菌LTA能诱导肿瘤细胞凋亡,并且TLRs特别是TLR2在LTA诱导肿瘤细胞凋亡中可能发挥着主要作用,TLR4可能仅起着协同作用。     

NKG2A的生物学特性与临床应用

NKG2A是主要表达于自然杀伤(natural killer,NK)细胞表面的抑制性受体,与NK细胞表面的激活性受体相互竞争,从而调控NK细胞的活性。近年来,抑制NKG2A免疫检查点可以恢复NK细胞活性从而杀伤肿瘤细胞,使得NKG2A成为抗肿瘤治疗的焦点之一。然而诸多研究发现,NKG2A还参与病毒感染、自身免疫等疾病,具有广阔的潜在临床价值。该文介绍了NKG2A蛋白的生物学特性、组织分布、蛋白功能及其与其他蛋白之间的相互作用,并重点综述了NKG2A在病毒感染、肿瘤和其他免疫性疾病中的应用,以期进一步促进NKG2A在相关疾病防治中的临床应用。     

nm23 和S- 100 蛋白在B16 黑色素瘤模型鼠的表达和意义

目的：检测荷瘤鼠体内mn23（肿瘤转移抑制因子）与S-100蛋白的表达,探讨其表达与肿瘤发生、转移的关系。方法：将B16恶性黑色素瘤细胞人工植入C57小鼠背部皮下,制荷瘤鼠模型,取对照组和病变皮肤作免疫组化染色。结果：早期肿瘤nm23和S-100蛋白阳性表达的数密度和面密度明显增高,与对照组、晚期组比较差异显著（P〈0．05）。结论：在B16黑色素瘤荷瘤鼠nm23和S-100蛋白的表达与肿瘤的发生、转移呈负相关。     

双歧杆菌脂磷壁酸对NF-κB在结肠癌细胞中表达的影响

目的探讨双歧杆菌脂磷壁酸（LTA）对NF-κB在结肠癌细胞HCT-116中表达的影响。方法采用免疫细胞化学染色、PAGE及Western blot等,分析经双歧杆菌LTA处理前后,NF-κB蛋白在结肠癌细胞HCT-116中表达的差异。结果经LTA处理后,NF-κB在HCT-116细胞中的表达明显降低,且呈剂量依赖性。结论双歧杆菌LTA可下调NF-κB的表达,对了解LTA诱导HCT-116细胞凋亡的机制提供了一定的实验依据。     

Inhibition of NK cell activity through TGF-beta 1 by down-regulation of NKG2D in a murine model of head and neck cancer

In an orthotopic murine model of head and neck squamous cell carcinoma (SCC VII/SF) we studied NK cell-mediated immunity following vaccination with a recombinant vaccinia virus expressing IL-2 (rvv-IL-2). SCC VII/SF tumor cells were injected into the oral cavity of C3H/HeJ mice on day 0. Mice were vaccinated on days 7, 10, and 14 with rvv-IL-2 and control vaccines. Phenotypes, numbers, and biological activities of NK cells were determined following vaccination. Levels of expression of NK-activating receptor NKG2D and CD16 on NK cell surface were assayed in the vaccinated mice. Expression of NKG2D ligands, Rae1, and H60 on SCC VII/SF cells was also examined. Vaccination with rvv-IL-2 resulted in expansion of NK cells. NK cells isolated from rvv-IL-2-vaccinated mice had significantly higher biological activities compared with mice treated with control vaccines. NK cells from tumor-bearing mice expressed significantly lower levels of NKG2D and CD16 compared with rvv-IL-2 vaccinated mice. SCC VII/SF tumors expressed NKG2D ligand Rae 1, although H60 was not present. SCC VII/SF tumors expressed high levels of TGF-beta1, which were down-modulated by vaccination with rvv-IL-2. Incubation of NK cells with tumor homogenate or cultured supernatant of SCC VII/SF cells reduced the expression of NKG2D and CD16. This inhibition appeared to be mediated by TGF-beta1. SCC VII/SF tumors in the oral cavity of the mice secrete high quantities of TGF-beta1, which reduce the expression of NK cell receptor NKG2D as well as CD16 and inhibits biological functions of NK cells.     

The heat shock protein HSP70 promotes mouse NK cell activity against tumors that express inducible NKG2D ligands

The stress-inducible heat shock protein (HSP) 70 is known to function as an endogenous danger signal that can increase the immunogenicity of tumors and induce CTL responses. We show in this study that HSP70 also activates mouse NK cells that recognize stress-inducible NKG2D ligands on tumor cells. Tumor size and the rate of metastases derived from HSP70-overexpressing human melanoma cells were found to be reduced in T and B cell-deficient SCID mice, but not in SCID/beige mice that lack additionally functional NK cells. In the SCID mice with HSP70-overexpressing tumors, NK cells were activated so that they killed ex vivo tumor cells that expressed NKG2D ligands. In the tumors, the MHC class I chain-related (MIC) A and B molecules were found to be expressed. Interestingly, a counter selection was observed against the expression of MICA/B in HSP70-overexpressing tumors compared with control tumors in SCID, but not in SCID/beige mice, suggesting a functional relevance of MICA/B expression. The melanoma cells were found to release exosomes. HSP70-positive exosomes from the HSP70-overexpressing cells, in contrast to HSP70-negative exosomes from the control cells, were able to activate mouse NK cells in vitro to kill YAC-1 cells, which express NKG2D ligands constitutively, or the human melanoma cells, in which MICA/B expression was induced. Thus, HSP70 and inducible NKG2D ligands synergistically promote the activation of mouse NK cells resulting in a reduced tumor growth and suppression of metastatic disease.     

Cutting edge: tumor rejection mediated by NKG2D receptor-ligand interaction is dependent upon perforin

We have investigated the primary immunity generated in vivo by MHC class I-deficient and -competent tumor cell lines that expressed the NKG2D ligand retinoic acid early inducible-1 (Rae-1) beta. Rae-1beta expression on class I-deficient RMA-S lymphoma cells enhanced primary NK cell-mediated tumor rejection in vivo, whereas RMA-Rae-1beta tumor cells were rejected by a combination of NK cells and CD8(+) T cells. Rae-1beta expression stimulated NK cell cytotoxicity and IFN-gamma secretion in vitro, but not proliferation. Surprisingly, only NK cell perforin-mediated cytotoxicity, but not production of IFN-gamma, was critical for the rejection of Rae-1beta-expressing tumor cells in vivo. This distinct requirement for perforin activity contrasts with the NK cell-mediated rejection of MHC class I-deficient RMA-S tumor cells expressing other activating ligands such as CD70 and CD80. Thus, these results indicated that NKG2D acted as a natural cytotoxicity receptor to stimulate perforin-mediated elimination of ligand-expressing tumor cells.     

IL-2-activated CD8+CD44high cells express both adaptive and innate immune system receptors and demonstrate specificity for syngeneic tumor cells

CD8(+) T cells depend on the alphabeta TCR for Ag recognition and function. However, Ag-activated CD8(+) T cells can also express receptors of the innate immune system. In this study, we examined the expression of NK receptors on a population of CD8(+) T cells expressing high levels of CD44 (CD8(+)CD44(high) cells) from normal mice. These cells are distinct from conventional memory CD8(+) T cells and they proliferate and become activated in response to IL 2 via a CD48/CD2-dependent mechanism. Before activation, they express low or undetectable levels of NK receptors but upon activation with IL-2 they expressed significant levels of activating NK receptors including 2B4 and NKG2D. Interestingly, the IL-2-activated cells demonstrate a preference in the killing of syngeneic tumor cells. This killing of syngeneic tumor cells was greatly enhanced by the expression of the NKG2D ligand Rae-1 on the target cell. In contrast to conventional CD8(+) T cells, IL-2-activated CD8(+)CD44(high) cells express DAP12, an adaptor molecule that is normally expressed in activated NK cells. These observations indicate that activated CD8(+)CD44(high) cells express receptors of both the adaptive and innate immune system and may play a unique role in the surveillance of host cells that have been altered by infection or transformation.     

Cancer immunoediting of the NK group 2D ligand H60a

Cancer immunoediting describes the process whereby highly immunogenic tumor cells are removed, or edited, from the primary tumor repertoire by the immune system. In immunodeficient mice, the editing process is hampered, and "unedited" tumor cells can be recovered and studied. In this study, we compared unedited and edited tumors for their expression of NK group 2D (NKG2D) ligands, a family of surface proteins expressed on tumor cells that can activate NK cell cytotoxic activity. We found that the expression of the NKG2D ligand H60a was more heterogeneous in groups of unedited 3'-methylcholanthrene sarcoma cell lines compared with that in edited 3'-methylcholanthrene sarcoma cell lines (i.e., some unedited cell lines expressed very high levels of H60a, whereas other unedited and edited cell lines expressed very low levels). We also found that some highly immunogenic cell lines displayed a bimodal distribution consisting of H60a-hi and H60a-lo cells. In one of these cell lines, the H60a-hi cells could be removed by passaging the cells through RAG2(-/-) mice, resulting in edited cell lines that were poor targets for NK cells and that displayed progressive tumor growth. This editing of H60a-hi cells required NK cells and NKG2D. Our studies show that the expression of H60a on tumors cells can be actively modulated by the immune system, thereby implicating this NKG2D ligand in tumor immunosurveillance.     

EAE tolerance induction with Hsp70-peptide complexes depends on H60 and NKG2D activity

Inflammation leads to induction of tissue stress conditions that might contribute to the generation of mechanisms limiting ongoing immune responses. We have shown previously that peptides derived from brain tissue of mice with experimental autoimmune encephalomyelitis (EAE) complexed with the chaperone heat shock protein 70 (Hsp70-pc) induce an NK-cell-dependent tolerance for subsequent EAE sensitization. We now present data that showed that the MHC class I-related glycoprotein H60 determines Hsp70-pc-induced EAE inhibition. Hsp70-pc led to significant and selective up-regulation of H60 expression in SJL/J mice, and Ab-blocking of H60 expression led to loss of EAE tolerance. Similarly, blocking of the NK cell receptor for H60, NKG2D, also reversed the Hsp70-pc-induced EAE inhibition. In contrast, in C57BL/6 mice H60 was not expressed, and Hsp70-pc-induced tolerance was not detected. The NK cell mediated Hsp70-pc-induced tolerance to EAE was dependent on modulation of dendritic cells function leading to diminished T cell reactivity to PLP. As, no increase of H60 expression on T cells from EAE mice immunized with PLP was detected, and no enhanced loss of CD3+ H60+ over CD3+ H60- cells in Hsp70-pc-induced EAE tolerance was found direct killing of H60+ PLP-reactive cells seems not to be involved in the Hsp70-pc-induced tolerance induction. We have provided evidence that Hsp70-pc-induced tolerance for EAE, mediated by NK cells, involves induction of H60 ligand and its interaction with NKG2D receptor. NK cells tolerization of EAE depends on altered dendritic cells activity leading to enhanced death of Ag reactive cells.     

NK cells use NKG2D to recognize a mouse renal cancer (Renca), yet require intercellular adhesion molecule-1 expression on the tumor cells for optimal perforin-dependent effector function

The NKG2D receptor on NK cells can recognize a variety of ligands on the tumor cell surface. Using a mouse renal cancer (Renca), we show that NKG2D recognition by NK cells was crucial for their ability to limit tumor metastases in vivo in both liver and lungs using perforin-dependent effector mechanisms. However, for the R331 cell line established from Renca, NKG2D recognition and perforin-dependent lysis played no role in controlling liver metastases. R331 cells were also more resistant to perforin-dependent lysis by NK cells in vitro. We therefore used these phenotypic differences between Renca and R331 to further investigate the crucial receptor:ligand interactions required for triggering lytic effector functions of NK cells. Reconstitution of R331 cells with ICAM-1, but not Rae-1gamma, restored NKG2D-mediated, perforin-dependent lysis. Interestingly, R331 cells were efficiently lysed by NK cells using death ligand-mediated apoptosis. This death ligand-mediated killing did not depend on NKG2D recognition of its ligands on tumor cells. This result suggests that the intracellular signaling in NK cells required for perforin and death ligand-mediated lysis of tumor target cell are quite distinct, and activation of both of these antitumor lytic effector functions of NK cells could improve therapeutic benefits for certain tumors.