全反式维甲酸对早期动脉粥样硬化大鼠模型外周调节性T细胞与辅助性T细胞17平衡的影响

目的 建立早期动脉粥样硬化大鼠模型,并探讨其外周CD4+ CD25+调节性T细胞(Treg)与辅助性T细胞17(Th17)平衡变化及全反式维甲酸对平衡的影响.方法 50只8周龄SD大鼠,随机分为对照组、高脂组、免疫组、免疫高脂组以及全反式维甲酸组,对照组、免疫组予正常饲料,其他三组予高脂饲料,免疫组、免疫高脂组以及全反式维甲酸组注射卵清白蛋白进行初始免疫和强化免疫.全反式维甲酸组同时予以全反式维甲酸灌胃,16周后获取血和动脉.检测血清脂质变化,主动脉HE染色以观察动脉病变；流式细胞术检测各组大鼠外周血Treg和Th17细胞表达率,酶联免疫吸附法检测血清相关细胞因子水平.结果 成功建立早期动脉粥样硬化大鼠模型.组织形态学显示免疫高脂组内膜增生；与免疫高脂组比较,免疫组及全反式维甲酸组程度较轻,对照组及高脂组动脉完好.高脂组及免疫高脂组血清胆固醇和低密度脂蛋白较对照组、免疫组有显著增加(均P＜ 0.05),而全反式维甲酸组与其他各组比较无统计学差异.与对照组及高脂组相比,免疫组及免疫高脂组大鼠Treg细胞表达及白细胞介素10(IL-10)、转化生长因子β水平显著降低,而Th17细胞表达及IL-17、IL-6水平明显增高(均P＜0.05),全反式维甲酸组Treg表达及相关细胞因子水平与免疫高脂组比较显著升高,而Th17表达及相关因子水平明显降低(均P＜ 0.05).结论 免疫损伤结合高脂喂养可形成早期动脉粥样硬化大鼠模型,该模型存在Treg与Th17细胞平衡失调,全反式维甲酸可通过影响Th17/Treg平衡发挥抗动脉粥样硬化效应.

The Effect of All-Trans-Retinoic Acid on the Balance of Peripheral CD4+CD25+ Regulatory T Cells and T Helper 17 Cells in Early Experimental Arteriosclerosis Rat Model

Aim To establish early experimental atherosclerosis (As) rat model, and to investigate peripheral CD4⁺CD25⁺ regulatory T cells (Treg)/T helper 17 cells (Th17) imbalance and the effects of all-trans-retinoic acid (ATRA) on the balance in the model.Methods Fifty 8-week-old Sprague Dawley rats were randomly divided into 5 groups: the normal group, cholesterol diet group, immune injury group, cholesterol diet plus immune injury group, and cholesterol diet + immune injury + ATRA group (ATRA group). Rats in normal group and immune injury group were fed with normal diet, and other groups were fed with cholesterol diet. Rats in immune injury group, cholesterol diet plus immune injury group and ATRA group were immunized by ovalbumin. Rats in ATRA group were treated with ATRA. For all the 5 groups, the samples of blood and aorta were obtained after 16 weeks. The levels of serum lipids and cytokines were measured by ELISA Histological changes in aorta were analyzed by HE staining, and the frequencies of Th17 and Treg cells were detected by flow cytometry.Results A rat model of early As was established successfully. The results of HE staining showed that there was an edematous thickening in the intima and a mild atrophy in the membrane of cholesterol diet plus immune injury group, and there was also a less extent on pathological changes in immune injury group and ATRA group. Serum total cholesterol (TC) and low density lipoprotein cholesterol (LDLC) concentrations in cholesterol diet group and cholesterol diet plus immune injury group were markedly increased compared with those in normal group and immune injury group (all P<0.05), but the levels of serum lipids in ATRA group had no significant difference compared with those in other groups. Expression of Treg and relative cytokines (interleukin-10 (IL-10), transforming growth factor beta (TGF-β)) was significantly lower while expression of Th17 and relative cytokines(IL-17, IL-6) was obviously higher in immune injury group and cholesterol diet plus immune injury group than those in normal group and cholesterol diet group (all P<0.05). The levels of Treg and relative cytokines were significantly increased while the levels of Th17 and relative cytokines in ATRA group were markedly decreased than those in cholesterol diet plus immune injury group (all P<0.05).Conclusions An early As rat model was successfully established by immune injury and cholesterol diet. The shift of the Th17/Treg balance from Treg cells towards Th17 cells exists in rat model, and ATRA may play an important role in inhibiting As development by influencing the peripheral Th17/Treg balance.