中文摘要：

目的探讨纳米氧化铁（Fe3O2）双歧杆菌脂磷壁酸（Bifidobacterium lipoteichoic acid，BLTA）对人胃癌荷瘤鼠体内细胞因子水平的影响，研究以纳米Fe3O4为载体的BLTA（Fe3O4-BLTA）对BGC-823胃癌移植瘤的抑制机制。方法用人低分化BGC-823胃癌细胞株移植到40只雄性BALB／c裸鼠建立胃癌荷瘤鼠模型。将随机分组的荷瘤鼠，进行不同浓度的纳米Fe3O4-BLTA复合物灌胃12d后处死。取移植瘤观察其肿瘤抑制率，应用免疫组化技术，检测瘤体内CD31微血管密度值（micmvessel density，MVD）及血管内皮生长因子（VEGF）的阳性率。提取腹腔巨噬细胞，用ELISA法检测细胞因子含量。结果纳米Fe3O4-BLTA低剂量组（10μg／d）对肿瘤的抑制率达到49％；纳米Fe3O4-BLTA低剂量组的CD31-MVD（57．000±6．790）与VEGF的表达（0．0224±0．0763）均比其他剂量组低（P〈0．01），VEGF的表达水平与肿瘤生长的抑制率呈负相关；纳米Fe3O4-BLTA高剂量组（100μg/d）和中剂量组（50μg／d）刺激巨噬细胞分泌细胞因子的差异有统计学意义（P〈0．01）。纳米Fe3O4-BLTA低剂量组诱导TNF—α水平较其他剂量组相对较高（39．4040±1．5590，P〈0．01）。结论纳米Fe3O4-BLTA复合物可诱导一些肿瘤相关因子和免疫细胞因子，与阴性对照组相比，在12d内对胃癌病灶鼠的肿瘤抑制效果明显（P〈0．01）。BLTA的纳米载体含量对机体吸收LTA有一定的影响。纳米Fe3O4-BLTA可利用其具有磁性的纳米级微粒，靶向定位于作用位点，作为靶向治疗胃癌新药物的研发对象。

英文摘要：

Objective To investigate the effect of lipoteichoic acid from Bifidobacterium loaded with magnetic particle nano-sized-Fe3O4 （nano-sized-Fe3O4-BLTA） on several cytokines in vivo expression in heterologous graft model for human gastric cancer in nude mice, and to analyze the inhibition mechanism of nano-sized-Fe3O4-BLTA on BGC-823 human gastric carcinoma transplanted tumor. Methods Forty male nude mice （BALB/c, nu/nu） were used for in vivo transplant tumor model, the experimental animals were randomly divided into five groups to administrated by several dosages of nano-sized-Fe3O4-BLTA, and were executed after 12 d. The tumors were collected and photographed, and the tumor tissues were used for different assays for measuring tumor inhibition. The peritoneal fluid was extracted to isolate the macrophages for cytokines assays. Using immunohistochemical staining for vascular endothelial growth factor （VEGF） and CD31 in tumor to investigate the tumor inhibition rate. Double antibody sandwich ELISA was used to detect the level of cytokine change. Results The mice treated with low dosage （10 μg/d） of nano-sized-Fe3O4- BLTA, the growth inhibition rate of tumor was 49% , and the levels of VEGF （0.0224 ±0.0763 ） and CD31 （57.000 ±6. 790） were lower than other treated groups （ P 〈 0.01 ）. The high dosage （ 100 μg/d） and medium dosage（50 μg/d） of nano-sized-Fe3O4-BLTA groups were significant difference （P 〈0.01 ） on the content of cytokines excreted by macrophages. The level of TNF-α（39. 4040 ±1. 5590） induced by the low dosage group was higher relatively （P 〈 0.01 ）. Conclusion Nano-sized-Fe3 O4-BLTA exerts an inhibiting effect on the growth of human gastric cancer in nude mice. Using nano-sized-Fe3 O4-BLTA, LTA can get more permeability and improve the therapy effect, which will be a new drug on the stomach cancer targeted therapy.