Inhibitory Effect of CTLA-4Ig Fusion Protein on Atherosclerosis in ApoE-/- Mice / 中山大学学报(医学科学版)

ABSTRACT

[Objective] To investigate the inhibitory effect of CTLA-4Ig fusion protein on atherosclerosis in the mice with an apolipoprotein-E gene defect fed on cholesterol diet.[Methods] Twenty-five male 10-week-old ApoE-/- mice were selected and fed on cholesterol diet for 4 weeks,5 out of which were executed at random as control group and their pathological sections were kept to observe the early fatty streaks.The other 20,divided into CTLA-4Ig treatment group,PBS group,IgG1 group,and blank group at random,5 in each.Three groups were given intraperitoneal injection of CTLA-4Ig (10 μg per time),PBS (100 μL per time),Rat-IgG1 (10 μg per time) respectively,twice a week,for 8 weeks.The blank group has no treatment.Followed by 8-week treatment,the whole aorta from the root to crotch of iliac artery was separated after anesthesia with the intraperitoneal injection of 1 % pentobarbital.Subsequently,the area ratio of plaque and lumen,the thickness ratio of endangium and tunica media,the lipid-soaking extent intra-plaque and the content of collagen fibrils and smooth muscle cells intra-plaque were analyzed by image-processing soft.[Results] After fed on cholesterol diet for 4 weeks,there were obviously atherosclerosis in the aorta in the ApoE-/- mice.There were typical atherosclerotic plaque in ApoE-/- mice fed on cholesterol diet after another 8 weeks.The area ratios of plaque and lumen in CTLA-4Ig group,PBS group,IgG1 group,and blank group were 0.27 ± 0.08,0.40 ± 0.08,0.43 ± 0.08,and 0.46 ± 0.10,and obviously increased than those in control group (0.05 ± 0.01,P ＜ 0.05).The thickness ratios of endangium and tunica media in four groups were 2.6 ± 0.6,6.0 ± 0.9,5.7 ± 0.8,and 5.9 ± 0.6 and obviously increased than those in control group (0.5 ± 0.1,P ＜ 0.05).The lipid-soaking extent intra-plaque in experimental groups were 26.0 ± 3.0,40.8 ± 5.7,40.6 ± 3.0,and 43.2 ± 5.7,and were obviously increased than those in control group (7.2 ± 1.4,P ＜ 0.05 ).It was found that the area ratio of plaque and lumen,the thickness ratio of endangium and tunica media,and the lipid-soaking extent intra-plaque in CTLA-4Ig group were significantly lower than those in PBS group,IgG1 group,and blank group (P ＜ 0.05),but there was no significant difference in those between the PBS group,IgG1 group,and blank group (P ＞ 0.05).The content of collagen fibrils in CTLA-4Ig group were 16.0 ± 1.1 and higher than those in PBS group,IgG1 group,and blank group (8.6 ± 1.2,9.2 ± 1.5,and 9.0 ± 1.3,P ＜ 0.05).The content of smooth muscle cells in plaque in CTLA-4Ig group were 11.8 ± 1.0 and higher than those in PBS group,IgG1 group,and blank group (7.8 ± 0.8,7.5 ± 0.9,and 7.3 ± 0.7,P ＜ 0.05).There was no significant difference in content of collagen fibrils and smooth muscle cells between the PBS group,IgG1 group,and blank group (all P ＞ 0.05).[Conclusion] CTLA-4Ig fusion protein could evidently inhibit the atherosclerosis progression and enhance the stability of plaque through increasing the content of collagen fibrils produced by smooth muscle cells intra-plaque in ApoE-/- mice fed on cholesterol diet.