Study on roles of angiostatic factor IP-10 and Mig in atherogenesis

干扰素诱导的10 kDa蛋白(IP-10)、干扰素诱导的T细胞α趋化因子(I-Tac)和干扰素-γ诱导的单核细胞因子(Mig)是T细胞介导的CXC趋化因子，也是抗血管生成因子。我们研究了IP-10在喂饲高胆固醇饮食的载脂蛋白E缺陷小鼠内膜新生血管和动脉粥样硬化中的作用。用抗CD31抗体和抗VWF抗体评价高胆固醇饲料喂养30周的小鼠很少观察到的内膜新生血管。我们制备了大鼠抗小鼠IP-10的单抗(抗IP-10单抗)，以阻断IP-10对载脂蛋白E缺陷小鼠的作用。小鼠从6周龄开始饲喂高脂饲料，12周至18周每周2次，分别给予抗IP-10单抗(第1组)或PBS(第2组)腹腔注射。两组均未见内膜新生血管。两组晚期动脉粥样硬化病变的平均面积相似。当6周龄小鼠喂饲高胆固醇饲料并注射抗IP-10单抗(第3组)或PBS(第4组)6周时，第3组早期动脉粥样硬化病变的平均面积比第4组小。这些结果提示IP-10可能在早期动脉粥样硬化病变的形成过程中起重要作用。除动物实验外，还研究了培养内皮细胞中IP-10、Mig和I-Tac基因表达的调控。我们已报道生物活性磷脂溶血磷脂酰胆碱(LysoPC)可抑制干扰素-γ诱导的内皮细胞趋化因子基因表达，提示其具有免疫调节作用。在本项目中，我们阐明了溶菌肽抑制作用的一个机制：溶菌素在转录后水平抑制了干扰素-γ诱导的ip-10、mig和i-tac的基因表达。

IFN-inducible protein of 10 kDa (IP-10), IFN-inducible T cell α chemoattractant (I-Tac) and monokine induced by IFN-γ(Mig) are T cell directed CXC chemokines and also anti-angiogenic factors. We investigated roles of IP-10 in intimal neovascularization and atherogenesis in apoE deficient mice fed high cholesterol diet. Intimal neovascularization was evaluated using anti-CD31 Ab and anti-VWF Ab and rarely observed in mice,fed a high cholesterol diet for 30 weeks. We prepared rat anti mouse IP-10 monoclonal antibody (anti-IP-10 mAb) to block the action of IP-10 in apoE deficient mice. Mice were fed a high cholesterol diet from 6 weeks of age and subjected to intra-peritoneal injection of anti-IP-10 mAb (group 1) or PBS (group 2) from 12 weeks to 18 weeks twice a week. Intimal neovascularization was hardly seen in both groups. The mean area of advanced atherosclerotic lesions was similar in both groups. When 6-week-old mice were fed a high cholesterol diet and injected with anti-IP-10 mAb (group 3) or PBS (group 4) for 6 weeks, the mean area of early atherosclerotic lesion of group3 tended to be smaller than that of group 4. These results suggest that IP-10 may play a significant role during the development of early atherosclerotic lesion. However, the number of mice to be studied should be increased to confirm the difference between groups 3 and 4. In addition to animal study, regulation of IP-10, Mig and I-Tac gene expression in cultured endothelial cells was studied. We have reported that a bio-active phospholipid lysophosphatidylcholine (lysoPC) inhibits the interferon (IFN)-γ-induced gene expression of these chemokines in endothelial cells, suggesting immuno-moduratory role of lysoPC. In this project, we elucidated a mechanism responsible for the inhibitory effect of lysoPC : lysoPC inhibits the IFN-γ-induced gene expression of IP-10, Mig and I-Tac at post-transcriptional level