摘要
目的:探讨树突状细胞(DC)及CD4+CD25+调节性T细胞在胰岛素自身抗原sc所诱导的小鼠胰岛素依赖性糖尿病(IDDM)的免疫耐受中的重要作用．方法:低剂量链脲佐菌素(STZ)(40 mg／kg)ip 连续5次在Balb／c小鼠体内建立IDDM模型,胰岛素(100 μg)与不完全弗氏佐剂(IFA,1:1)混合液sc 1次／wk,连续4 wk．模型建立后每周测定血糖,5 wk时处死动物,取胰腺进行病理组织学检查．分离骨髓DC前体及脾脏T淋巴细胞并进行体外培养．采用流式细胞术测定DC表型和CD4+CD25+调节性T细胞,以同种淋巴细胞刺激实验检测DC刺激淋巴细胞增殖功能．结果:胰岛素sc 4 wk后可明显降低小鼠的血糖,与模型对照组有极显著差异(13．79± 2．71 mmol/L vs 20．98±1．43 mmol／L,P<0．05), 胰岛内炎症细胞浸润减少,组织结构完整． IDDM模型建立后,小鼠骨髓来源树突状细胞CD11c表达为26．4％,DC分化异常,而正常小鼠CD11c表达为47．5％;混合淋巴细胞反应中DC刺激能力减弱,刺激指数分别为1．47± 0．01和1．32±0．01(刺激细胞和反应细胞比例分别为1:10和1:20),与正常小鼠相比,差别具有极显著性意义(P值均小于0．01)．脾脏 CD4+CD25+调节性T细胞减少到1．43％,而正常小鼠为5．09％．与此相反,胰岛素自身抗原连续应用后,不仅使血糖得到控制,表达 CD11c的树突状细胞数量增加,CD86和MHC- Ⅱ表面分子表达降低到26．6％和28．8％,刺激淋巴细胞反应的能力弱于正常DC,但强于模型小鼠的DC,刺激指数分别为2．30±0．06(1: 10)和2．17±0．02(1:20),CD4+CD25+调节性T 细胞数量上升到7．15％．结论:胰岛素sc可预防STZ所致小鼠IDDM的发生,自身抗原可以通过改善功能异常的树突状细胞．诱导CD4+CD25+调节性T细胞分化在模型小鼠体内建立免疫耐受．
AIM： To investigate the important roles of dendritic cells （DC） and CD4^＋CD25^＋ regulatory T cells in immune prevention against insulin dependent diabetes （IDDM） by autoantigen insulin administration.
METHODS： The model of IDDM was established by intraperitoneal injection of low-dose streptozotocin （STZ） 40 mg/kg per day for 5 consecutive days in Balb/c mice. The bovine insulin （100 μg） in incomplete Freund＇s adjuvant （IFA, emulsified 1 ： 1） was given subcutaneously to the mice weekly for 4 weeks. The blood glucose was examined once a week and all the mice were killed after 5 weeks. Pancreas tissues were collected for histopathological examination. DC precursor cells from bone marrow and lymphocytes from spleen were isolated. The phenotype of DC and CD4^＋ CD25^＋ regulatory T cells were analyzed by fluorescence activated cell sorter （FACS）. DC-stimulated proliferation of lymphacytes was determined by allo-mixed lymphocyte reaction （aMLR）.
RESULTS： The level of blood glucose was decreased significantly after insulin injection in comparison with that in the model control group （13.79 ± 2.71 mmol/L vs 20.98 ± 1.43 mmol/L, P 〈 0.05）. Fewer lymphocytes infiltration was observed and pancreatic histological structure was intact. The surface marker CD11c on DC from bone marrow was decreased markedly in IDDM mice （26.4%） than that in normal mice （47.5%）. DC differentiated abnormally, and the capacity of stimulating proliferation of allogeneic T cell was weakened as compared with that of normal mice （1.47 ± 0.01 vs 2.93 ± 0.01, P 〈 0.01, and 1.32 ± 0.01 vs 2.94 ± 0.02, P 〈 0.01, at DC/T ratios of 1 ： 10 and 1 ： 20, respectively）. The percentage of CD4^＋CD25^＋ T cells were decreased to 1.43%, while it was 5.09% in normal mice. In contrast, blood glucose in mice given insulin subcutaneously was well controlled, and the amount of DC with CD11c was increased （50% approximately）; the expression of CD86 and MHC-Ⅱ was low （26.6% and 28.8%, respectively） and MLR showed that DC capacity in stimulating T cell proliferation was lower than those from the normal mice, but higher than those from IDDM model mice （2.30 ± 0.06 and 2.17 ± 0.02, at DC/T ratios of 1 ： 10 and 1 ： 20, respectively）; the percentage of CD4^＋CD25^＋ T cells from spleen was enhanced to 7.15%.
CONCLUSION： Subcutaneous administration of insulin can confer protection to mice against IDDM induced by STZ. The immune protection of autoantigen may be associated with the establishment of immune tolerance by improving the function of abnormal DC and promoting the production of CD4^＋CD25^＋ T cells in vivo.
出处
《世界华人消化杂志》
CAS
北大核心
2006年第7期687-692,共6页
World Chinese Journal of Digestology
基金
国家自然科学基金资助项目
No.30200343
