两歧双歧杆菌在荷瘤鼠模型中的靶向定植及对巨噬细胞的免疫激活

Target colonization of Bifidobacterium bifidum in tumor-bearing mouse model and its immune activation on macrophages

目的:证实两歧双歧杆菌(Bifidobacterium bifidum,B.bifidum KLDS2.9502)在荷瘤裸鼠模型中的靶向定植作用,检测其对腹腔巨噬细胞的免疫刺激作用。方法:建立人胃癌移植瘤裸鼠模型,尾静脉注射B.bifidum KLDS2.9502,摘取心、肝、脾、肺、肾及瘤体组织,采用石蜡包埋技术和体外厌氧培养的方法,在光学显微镜下观察双歧杆菌在荷瘤裸鼠心、肝、脾、肺、肾和瘤组织中的生存和分布情况。提取腹腔巨噬细胞,在激光共聚焦显微镜下观察巨噬细胞核内DNA和RNA的表达;MTT法和中性红吞噬试验检测荷瘤裸鼠腹腔巨噬细胞的能量代谢能力和吞噬能力;硝酸还原酶法和ELISA法分别检测巨噬细胞分泌NO和肿瘤坏死因子-α(tumor necrosis factor-α,TNF-α)的量。结果:通过对组织石蜡切片鉴定、组织匀浆体外厌氧培养检测发现B.bifidum KLDS2.9502只存在并生长于瘤体组织中,并能刺激荷瘤鼠腹腔巨噬细胞能量代谢能力和吞噬能力的增强(P<0.05),显著提高巨噬细胞分泌NO[(103.48±0.26)μmol/L]和TNF-α[(45.32±0.85)pg/mL]的水平(P均<0.01)。结论:两歧双歧杆菌能特异性定植于荷瘤鼠的瘤体中,并免疫激活腹腔巨噬细胞,提高相关肿瘤细胞毒性因子NO和TNF-α分泌水平,提示其可作为一种靶向治疗肿瘤的转基因生物载体。

Objective：To demonstrate the colonization of Bifidobacterium bifidum（B.bifidum KLDS2.9502） in tumor-bearing mouse model and its immune activation on peritoneal macrophages.Methods：The human stomach xenografted carcinoma models were built up in nude mice.B.bifidum KLDS2.9502 was injected through tail vein every two days.Tissue samples of the heart,liver,spleen,lung,kidney and the whole tumor were isolated on 10 days later.These tissues were imbedded by paraffin and cultured in anaerobic condition in vitro.The distribution and colonization of B.bifidum KLDS2.9502 were tested under microscope.Peritoneal macrophages were collected,and the DNA and RNA expressions in nucleus of macrophages were observed by Laser S confocal microscopy.The phagocytic activity and metabolic ability were measured by Neutral Red phagocytic test and MTT assay,respectively;the NO production and level of tumor necrosis factor-α（TNF-α） secreted form peritoneal macrophages were detected by the method of nitrifying ferment and ELISA,respectively.Results：Compared with the control group,B.bifidum KLDS2.9502 only existed and grew in tumor tissues,instead of other tissues,which was confirmed by paraffin imbedding techniques and anaerobic culture in vitro.In addition,the phagocytic activity and metabolic ability of peritoneal macrophages irritated by B.bifidum KLDS2.9502 were increased（P〈0.05）.The level of NO was significantly elevated to（103.48±0.26） μmol/L by B.bifidum KLDS2.9502（P〈0.01）.TNF-α secretion [（45.32±0.85） pg/mL] was significantly increased（P〈0.01）.Conclusion：B.bifidum KLDS2.9502 specifically exists in tumor bodies in tumor bearing mice,and enhances the immune ability of murine peritoneal macrophages,greatly increases the levels of cytotoxic factor NO and TNF-α,suggesting that it could be used as a gene transfer vector for anti-tumor biotherapy