胸腺肽α1联合DC疫苗对结肠癌体内外抗肿瘤的效应

目的观察胸腺肽α1(Tα1)对结肠癌细胞裂解物(TuLy)负载DC(LyDC)的表型和功能的影响,以及二者联合应用对裸鼠结肠癌的治疗作用.方法从健康人外周血单个核细胞中常规诱导培养未成熟DC(imDC),并负载TuLy后制备LyDC疫苗.Tα1体外刺激imDC、LyDC,流式细胞术(FCM)检测DC表型变化;ELISA法检测LyDC与自体T细胞共培养时,Tα1对LyDC分泌IL-12以及活化T细胞分泌IFN-γ水平的影响;MTT法检测LyDC经Tα1刺激后所诱导的细胞毒活性的变化.对HT-29结肠癌裸鼠模型行人源化T细胞免疫重建,观察LyDC与Tα1联合应用时的体内抗肿瘤效果.结果Tα1刺激后的imDC、LyDC表型HLA-DR、CD80、CD86、CD83均上调(P＜0.01);Tα1刺激组上清液中细胞因子IL-12和IFN-γ的水平较未刺激组增加(P＜0.05,P＜0.01);LyDC经Tα1刺激后诱导的CTL细胞毒活性较未经Tα1刺激组增强(P＜0.01).结肠癌裸鼠模型体内的人源化细胞免疫重建成功,在接种HT-29细胞58 d后,LyDC Tα1组和LyDC组的抑瘤率分别为60.41%和37.20%,二组之间瘤体积及瘤质量比较具有统计学意义(P＜0.01).结论Tα1可促进DC分化成熟,并能增强LyDC诱导的CD4 Th1细胞反应和CTL的杀伤效应.Tα1与LyDC疫苗联合应用时具有较好的免疫佐剂活性和抗肿瘤作用.

The anti-tumor efforts of thymosin α1 on tumor lysate-pulsed dendritic cells in colon cancer in vitro and in vivo

AIM: To investigate the effects of thymosin alpha1 (Talpha1) on the differentiation, maturation and function of tumor lysate-pulsed dendritic cells (LyDCs) in vitro, and to study the antitumor effects on tumor models of the nude mice bearing colon cancer in vivo. METHODS: Immature DCs (imDCs) were prepared routinely from human peripheral blood mononuclear cells. The LyDCs were prepared from the imDCs loaded with lysate of HT-29 tumor cell line. The phenotypes of imDCs and LyDCs pre- or post-stimulated by Talpha1 were analyzed by flow cytometry. Autologous T cells were cocultured with LyDCs in the presence or absence of Talpha1 2 days later. IL-12 secretion of LyDCs and IFN-gamma secretion of the activated T cells in the supernatants were measured by ELISA. The in vitro cytotoxicity of antigen specific cytotoxic T lymphocytes (CTLs) induced by LyDCs which were treated with Talpha1 was evaluated by MTT assay. A humanized nude mice model bearing colon cancer was established. The in vivo antitumor activity was evaluated in the humanized nude mice after the treatment with LyDCs plus Talpha1 or LyDCs alone. RESULTS: The expression levels of HLA-DR, CD80, CD86 and CD83 in imDCs and LyDCs were markedly up-regulated after the stimulation with Talpha1 respectively (P<0.01). The levels of IL-12 and IFN-gamma were also significantly increased in the presence of Talpha1 (P<0.05 and P<0.01, respectively). Cytotoxicity induced by LyDCs treated with Talpha1 was significantly enhanced (P<0.01) as compared with LyDCs in vitro. The humanized cellular immunity was successfully established in the nude mice model. On the 58 th day after the inoculation of tumor cells, the inhibitory rate of tumor growth was significantly higher in the group treated with LyDCs plus Talpha1 than that in the group treated with LyDCs alone (60.41% and 37.20%, respectively; P<0.01). CONCLUSION: Talpha1 can induce the functional maturation of DCs and enhance the immune response of CD4+Th1 arm and cytotoxicity induced by LyDCs. Talpha1 has a synergistic antitumor effect. It might be a promising adjuvant candidate for DC-based immunotherapy of gastrointestinal carcinomas.