【摘要】 背景与目的:研究表明,endoglin是肿瘤血管生成的标志性分子,用抗endoglin单克隆抗体被动免疫治疗可以有效抑制肿瘤生长,而异种DNA疫苗可以打破自身同源分子的免疫耐受。因此,本研究用猪endoglin胞外段真核表达质粒(ppEDG)作为异种DNA疫苗,了解该DNA疫苗是否具有抑制小鼠结肠癌生长的作用,并探讨其作用的免疫学机理。方法:观察免疫治疗后的荷瘤小鼠肿瘤体积和生存情况,用免疫组化方法(抗CD31)观察肿瘤组织血管生长并计算肿瘤微血管密度,用Westernblot和ELISA方法检测荷瘤小鼠免疫治疗后的血清是否含有抗自身endoglin的抗体以及抗体亚型,用ELISPOT方法检测荷瘤小鼠脾脏中分泌抗自身endoglin抗体的B淋巴细胞。结果:肿瘤接种18天后,ppEDGDNA疫苗主动免疫治疗组肿瘤体积明显小于空质粒(e-p)对照组及生理盐水对照组(P<0.05),存活时间明显延长(P<0.001)。ppEDG组、e-p组和生理盐水组肿瘤组织微血管密度计数分别为19.2±4.5、76.9±14.4和81.4±16.9(P<0.001)。治疗组小鼠血清中含有抗自身endoglin的抗体,抗体亚型主要为IgG1和IgG2b。三组小鼠分泌抗自身endoglin抗体的B淋巴细胞数分别为82.5±14.1、3.6±1.3和4.7±2.0(P<0.001)。结论:ppEDGDNA疫苗诱导抗自身endoglin抗体产生,从而抑制肿瘤血管生成和肿瘤生长。更多还原

【Abstract】 BACKGROUND & OBJECTIVE: Endoglin is a marker of tumor angiogenesis. Increasing evidences proved that passive immunotherapy with anti-endoglin monoclonal antibody can effectively inhibit tumor growth, and xenogeneic homologous DNA vaccine can inhibit cross antitumor immunity. This study was to explore the inhibitory effect of a DNA vaccine encoding the extracellular domain of porcine endoglin (ppEDG) on tumor growth in a mouse colon carcinoma model. METHODS: ppEDG was used as a DNA vaccine to actively immunize the colon carcinoma-bearing mice. Tumor volume and survival rate of the mice were observed in 3-day intervals. Microvessel density (MVD) was detected by immunohistochemistry; antibodies against self-endoglin were detected by Western blot and ELISA; the B cells that secrete auto-antibodies against self-endoglin were detected by ELISPOT assay. RESULTS: Eighteen days after tumor cell inoculation, the tumor volume was significantly smaller in ppEDG-immunized group than in empty plasmid (e-p) group and normal saline (NS) group (P<0.05), and the survival time was significantly longer in ppEDG-immunized group than in the control groups (P<0.001). MVD was significantly lower in ppEDG-immunized group than in e-p group and NS group (19.2±4.5 vs. 76.9±14.4 and 81.4±16.9, P<0.001). The antibodies against self-endoglin were identified in ppEDG-immunized group; the major subtypes were IgG1 and IgG2b. The auto-antibody-producing B cells were much more in ppEDG-immunized group than in e-p group and NS group (82.5±14.1 vs. 3.6±1.3 and 4.7±2.0, P<0.001). CONCLUSION: ppEDG DNA vaccine could induce the production of auto-antibodies against self-endoglin, which further inhibit angiogenesis and growth of colon carcinoma.更多还原