1-甲基色氨酸对胰腺癌荷瘤鼠中调节性T细胞数量变化的影响

1-MT enhanced potency of dendritic cells pulsed with tumor cell lysate by downregulation of CD4 ^＋ CD25^＋ treg

目的 观察1-甲基色氨酸（1-MT）对胰腺癌荷瘤鼠中调节性T细胞（Treg）数量变化的影响,比较树突状细胞（DC）疫苗与1-MT联合应用前后抗肿瘤作用的强弱.方法 建立小鼠胰腺癌模型;利用流式细胞术检测荷瘤鼠应用1-MT前后肿瘤组织周围引流淋巴结（TDLNs）及脾脏中CD4^＋ CD25^＋T细胞占CD4^＋T比例;荧光定量聚合酶链反应（PCR）测量Foxp3在TDLNs及脾脏mRNA水平;利用肿瘤细胞裂解物冲击DC制备DC疫苗,并根据是否与1-MT联合应用分组（各组均为n=8）;观测各组肿瘤体积的差异.结果 应用1-MT后,荷瘤鼠CD4^＋ CD25^＋ T细胞占CD~＋T细胞的比例明显低于未应用组（TDLNs）分别为（16.01±2.21）%和（25.00±2.16）%（P〈0.05）;脾脏分别为（13.11±1.93）%和（22.14±2.33）%（P〈0.05,P〈0.01）;应用1-MT组Foxp3 mRNA表达水平显著低于未应用组,应用1-MT组相对表达值：TDLNs0.947±0.216、脾细胞1.198±0.347,而未应用组分别为：1.927±0.256、1.798±0.237（P〈0.05）;1-MT＋DC疫苗组肿瘤生长显著受到抑制,第36天肿瘤体积为（789.0±111.0）mm^3;显著小于DC疫苗组、1-MT组及对照组,肿瘤体积分别为：（1768.0±251.3）、（1854.0±192.1）、（1899.0±201.2）mm^3（P〈0.01）.结论 1-MT可以有效抑制胰腺癌荷瘤鼠癌组织周围引流淋巴结及脾脏CD4^＋ CD25^＋ Treg细胞的数量增加,从而增强DC疫苗抗肿瘤作用.

Abstract：Objective To determine whether 1-methyl-tryptophan （1-MT, an IDO inhibitor） might reduce CD4^＋ CD25^＋ Treg and improve the anti-tumor effects of dendritic cells pulsed with tumor cell lysate in the murine pancreas adenocarcinoma model. Methods Pan02 cell line was injected into syngeneic C57BL/6 mice. 1-MT was administered to pancreas adenocarcinoma mice and its effect on the prevalence of regulatory T cells （Treg） in tumor draining lymph nodes （TDLNs） and spleen was investigated. The prevalence of Treg in the TDLNs and tumor spleen （TS） was detected by using flow cytometry. The expression level of Foxp3 mRNA was detected in the spleen and TDLN by real-time PCR. To prepare the DC vaccine,dendritic cells were pulsed with tumor cell lysate. This DC vaccine, as a single agent or in combination with 1-MT, was administered to pancreas adenocarcinoma mice. The anti-tumor effects in different treatment were deter mined by regular observation of tumor development. Results There was statistically significant difference in the percentage of CD4^＋ CD25^＋ T lyraphocytessignificant between 1-MT-treated group [TDLNs （16.01 ± 2.21）% and TS （13. 11 ± 1. 93）%] than PBS control group [TDLNs （25. 00 ± 2. 16）% and TS （22.14 ±2.33）%] （P〈0.05,P〈0.01）. In 1-MT-treated group,the Foxp3 expression was significantly lower in TDLN and TS than in control LN and spleen. Furthemore,in 1-MT ＋ DC vaccine-treated group,the tumor growth rate was significantly slower than in groups of DC vaccine, 1-MT and PBS （the tumor volume was （789.0 ±111.0）, （1768.0 ±251. 3）, （1854.0 ±192. 1）,（1899.0 ±201.2） mmJ at the 36th day af ter tumor challenge, respectively （P 〈 0. 01）. Conclusion 1-MT can enhance anti-tumor effects of den dritic cells pulsed with tumor cell lysate by downregulating the expression of CD4^＋ CD25^＋ Treg.