三硝基苯磺酸诱导的小鼠结肠炎模型中调节性T细胞的分布变化

Changes of regulatory T cells distribution in trinitrobenzene sulfonic acid induced mice colitis

目的研究三硝基苯磺酸（TNBS）诱导的小鼠结肠炎模型中结肠与脾的调节性T细胞（Treg）亚群分布的变化，以及地塞米松对其的治疗作用。方法40只小鼠均分为健康对照组、乙醇对照组、模型组和地塞米松治疗组。模型组予2．5mgTNBS灌肠，健康对照组和乙醇对照组分别予0．9％氯化钠溶液和乙醇溶液灌肠，地塞米松治疗组自造模后第1天起每日予地塞米松水溶液0．6mg／kg腹腔注射。造模后第3、5、7天处死小鼠，观察各组小鼠体质量，流式细胞术检测脾及肠系膜淋巴结CD4＋CD25＋叉状头转录因子3（Foxp3）＋。细胞比例。造模后第7天观察其疾病活动指数（DAI）、结肠病理组织学评分，采用免疫组织化学检测结肠Foxp3表达。组间比较采用t检验。结果与健康对照组和乙醇对照组相比，模型组小鼠体质量明显下降（t=3．604、2．422，P均〈0．05），DAI、结肠病理组织学评分升高（t=2．630、2．438，P均〈0．05；t=7．910、6．600，P均〈0．01）。地塞米松治疗组与模型组相比，DAI有所下降（t=2．076，P〉0．05），病理学表现明显好转（t=2．320，P％0．05）。造模后7d，模型组小鼠脾及肠系膜淋巴结CD4＋CD25＋Foxp3’细胞比例分别为3．320％±0．533％、2．888％±0．379％，低于健康对照组的5．379％±0．518％和4．688％±0．553％（t=2．769、2．686，P均〈0．05），地塞米松治疗后有所回升。小鼠结肠组织Foxp3阳性细胞数在健康对照组、模型组、地塞米松治疗组分别为（3．000土0．577）、（7．200±0．800）、（6．000±0．931）个／高倍视野，模型组及地塞米松治疗组表达增多（t=4．257、2．739，P均〈0．05）。结论TNBS诱导的小鼠结肠炎模型中存在结肠与脾的Treg亚群分布比例异常，地塞米松可能通过上调Treg比例以改善模型的疾病状态。

Objective To investigate the changes of regulatory T cells （Treg） distribution in trinitrobenzene sulfonic acid （TNBS） induced mice colitis and the therapeutic effects of dexamethasone （DEX）. Methods A total of 40 mice were evenly divided into healthy control group, ethanol control group, model group and DEX treatment group. The model group was given 2.5 mg TNBS through enema, while healthy control group and ethanol control group were administered with 0. 9~ NaC1 solution and ethanol solution respectively. DEX treatment group was intraperitoneal injected with DEX （0.6 mg/kg） since the first day after modeling. Mice were executed at 3rd, 5th and 7th day after modeling, mice body weight of each group were observed and the rate of both CD25＋ forkhead box P3 （Foxp3） positive and CD4 positive cells in spleen and mesenteric lymph nodes were measured by floweytometry. At the 7th day, disease activity index （DAD and colonic histopathological score were evaluated, the expression of Foxp3 in colon tissue were measured by immunohistochemistry, t-test was applied for each group comparison. Results Compared with healthy control group and ethanol control group, the mice body weight of model group significantly decreased （t=3. 604 and 2. 422, both P〈0.05）; DAI score and colonic histopathologic score increased （t=2. 630 and 2. 438, both P%0.05; t=7.910 and 6. 600; both P〈0.01）. Compared with the model group, DAI score decreased （t 2. 076, P〉0. 05） and histopathologic severity in DEX treatment group improved significantly （t 2. 320, P〈0.05）. At the 7th day after modeling, the rate of both CD25＋ Foxp3 positive and CD4 positive ceils in spleen and mesenteric lymph nodes of model group was 3. 320%＋ 0. 533% and 2.888%±0. 379%, lower than that of healthy control group （5. 379%±0. 518% and 4. 688%±0.553%; t 2. 769 and 2. 686; both P〈0.05）. After DEX treatment, the rate increased. The expression of Foxp3 in colon tissue of healthy control group, model group and DEX treatment group was 3.000±0. 577, 7. 200±0. 800 and 6. 000±0. 931 per high power field respectively, and the expression of model group and DEX group significantly increased （t 4. 257 and 2. 739, both P〈0.05）. Conclusions The distribution of Treg in spleen and colon were abnormal in TNBS induced mice colitis model. DEX may improve the disease state of the mice model through upregulating Treg.