CTLA-4Ig融合蛋白抑制apoE基因缺陷小鼠动脉粥样硬化机理研究

Study on the mechanisms of inhibitory effect of CTLA-4Ig fusion protein on atherosclerosis in apoE deficient mice

目的探讨CTLA-4Ig融合蛋白抑制高脂饮食饲养的载脂蛋白E基因缺陷小鼠（apoE-／-）动脉粥样硬化（AS）的作用机理？方法30只10周龄apoE-／-小鼠，随机分为3组（每组10只），高脂饮食饲养，分别采用CTLA-4Ig、IgG1、PBS腹腔注射（每周2次）。12周后取小鼠主动脉进行病理学检查，检测AS病变相关指标，包括斑块面积／管腔面积比、血管内膜／中膜厚度比，斑块内脂质、胶原和平滑肌细胞含量；取血清检测总胆固醇浓度和CRP、sICAM-1、IFN-1、IL-10、TGF—β1浓度。结果高脂饮食饲养12周后，形成明显AS斑块，但CTLA-4Ig组病变最轻。CTLA-4Ig组、IgG1组和PBS组的斑块面积／管腔面积比、血管内膜／中膜厚度比、斑块内脂质含量和胶原含量差异均有统计学意义（P〈0．05），CTLA-4Ig组斑块面积／管腔面积比、血管内膜／中膜厚度比和斑块内脂质含量均显著低于IgG1组和PBS组（P〈0．05），其斑块内胶原含量高于IgG1组和PBS组（P〈0．05），而后2组间上述指标的差异均无统计学意义（P〉0．05）；3组间斑块内平滑肌细胞含量差异不具有统计学意义（P〉0．05）。CTLA-4Ig组、IgG1组和PBS组的血清总胆同醇浓度差异不具有计学意义（P〉0．05），3组的血清CRP、sICAM—1、IFN-γ、IL-10、TGF—β1水平差异均有统计学意义（P〈0．05），CTLA-4Ig组m清CRP、sICAM-1、IFN-1水平降低，血清IL-10、TGF-β1水平升高，而后2组间上述指标的差异均无统计学意义（P〉0．05）。结论CTLA-4Ig融合蛋向抑制高脂饮食饲养的apoE（-／-）小鼠动脉粥样硬化进程，可能与阻断B7／CD28通路、抗炎作用、促进Th2檄化、及影响凋节性T细胞功能等有关。

Objective To investigate/he mechanisms of inhibitory effect of CTLA-4Ig fusion protein on atherosclerosis in mice with apolipoprolein-E gene deficient fed on high cholesterol diet. Methods 30 male 10-weekold apoE（-/-） mice led on cholesterol diet were randomly divided into CTLA-4Ig treatment group, IgG1 group and PBS group. There were l0 mice in each group. Mice in the three groups were given intraperitoneal injection of CTLA-41g （ 10μg per time） , Rat-IgG1 （ 10 μg per time）, PBS （ 100 μL per time） respectively, twice a week. Followed by 12-week treatment, the whole aorta from the root to crotch of iliac after＇ was separated and sera were collected. Suhsequently, the area ratio of plaque and lumen in cross section, the thickness ratio of endangium and tunica media, the intraplaque lipid-soaking extent and the amount of intraplaque collagen fihrils and smooth musele cells were analyzed by image-processing. The concentrations of total cholesterol, CRP, sf CAM-1, IFN-γ, IL-10 aud TGF-β1 in the sera were measured. Results There were typical atheroselerotic plaques in apoE（-/-） mice fed on high cholesterol diet for 12 weeks. The plaqne was mild in CTLA--4Ig group. There were significant difference in the area ratio of plaque and lumen, the thickness ratio of endangium and tunica media, the intraplaque lipid-soaking extent, and the amount of collagen fibrils among the three groups （ all P 〈 0. 05）. It was found that the area ratio of plaque and lumen, the thickness ratio of endangium and tunica media, and the intraplaque lipid-soaking extent were significantly lower and the amount of collagen fibrils was significantly higher in CTLA-4Ig group than those in IgG1 group and PBS group（ all P 〈 0.05 ）, but there was no significant difference in those between the IgG1 group and PBS group （ all P 〉 0.05 ）. There were no significant difference in the amount of smooth muscle cells in the three groups（ P 〉0. 05 ）. There were no significant difference in the concentration of total cholesterol in the sera in the three groups （P 〉 0. 05 ）. There was significant difference in the concentrations of CRP, sICAM-I, IFN-γ, IL-10, and TGF-β1 in the sera in the three groups （ all P 〈 0. 05）. It was found that CTLA-4Ig could decrease the crncentrations of CRP, sICAM-I and IFN-γ and increase IL-10 and TGF-β1 in the sera, but IgG1 and PBS could not. Conclusion CTLA-4Ig fusion protein could inhibit the atherosclerosis progress in apoE（-/-） mice fed on high cholesterol diet and it＇ s effect might be associated with blocking B7/CD28, anti-inflanunation, promoting Th2 polarization and affecting regulatory T cells.