Jiang Tie-Jian, Zhou Zhi-Guang
Department of Endocrinology, Xiangya Hospital, Central South University, Changsha 410008, China.
Zhong Nan Da Xue Xue Bao Yi Xue Ban. 2007 Aug;32(4):615-9.
To investigate the effect of oral administration of insulin on insulitis beta cell apoptosis and diabetes in non-obese diabetic (NOD) mice, and to explore the mechanism of immune tolerance induced by insulin.
Eighty-six female NOD mice were randomly divided into an insulin group (n=43) and a phosphate buffered saline (PBS) group (n=43). From 4 weeks of age, the recombinant human insulin (Humulin R) 1 mg (70 microL) was administrated in the oral insulin group and 70 microL PBS in the control group respectively, twice per week before 12 weeks of age and then once weekly until 30 weeks. Insulitis and beta cell apoptosis of islets were observed at 12 weeks. IL-4 and IFN-gamma in the sera were measured by enzyme linked immunosorbent assay (ELISA). The expression levels of I-Abeta(g7), IL-4, IFN-gamma, IL-1beta, Fas and TGF-beta mRNA of islets, and IL-4, IFN-gamma, TGF-beta mRNA of Peyer's patch were measured by reverse transcription-polymerase chain reaction (RT-PCR) at 12 weeks.
The incidences in the insulin group were significantly lower than those in the PBS group (55.6% vs 85.7% at 30 weeks, 70.4% vs 96.4% at 52 weeks, P<0.05). The insulitis scores in the insulin group were lower than those in the PBS group, but there was no statistical significance. Fas expression on islets and apoptotic beta cell rates in the insulin group were lower than those in the PBS group (P<0.05). In the insulin group, serum IL-4 levels were higher, and IFN-gamma levels were lower than those in the PBS group (P<0.05). The levels of I-Abeta(g7), IFN-gamma, IL-1beta and Fas mRNA transcription in islets and IFN-gamma mRNA transcription in Peyer's patch were both lower in the insulin group, and IL-4, TGF-beta mRNA levels were higher than those in the PBS group (P<0.05).
The specific autoantigen insulin may induce the immune tolerance and prevent the diabetes in NOD mice, but it cannot block the progression of insulitis. Oral administration of insulin can induce the regulatory T cells, and make Th1 to Th2 cytokine shifts in the system and islets, thus preventing the Fas-mediated beta-cell apoptosis and diabetes.
探讨口服胰岛素对非肥胖型糖尿病（NOD）小鼠胰岛炎、β细胞凋亡及糖尿病的影响，并探讨胰岛素诱导免疫耐受的机制。
86只雌性NOD小鼠随机分为胰岛素组（n = 43）和磷酸盐缓冲液（PBS）组（n = 43）。从4周龄开始，口服胰岛素组给予重组人胰岛素（优泌林R）1mg（70μL），对照组给予70μL PBS，12周龄前每周2次，12周龄后每周1次，直至30周。观察12周时胰岛炎和胰岛β细胞凋亡情况。采用酶联免疫吸附测定（ELISA）法检测血清中IL - 4和IFN - γ水平。12周时，采用逆转录 - 聚合酶链反应（RT - PCR）检测胰岛中I - Abeta(g7)、IL - 4、IFN - γ、IL - 1β、Fas和TGF - β mRNA的表达水平，以及派尔集合淋巴结中IL - 4、IFN - γ、TGF - β mRNA的表达水平。
胰岛素组发病率显著低于PBS组（30周时分别为55.6%和85.7%，52周时分别为70.4%和96.4%，P < 0.05）。胰岛素组胰岛炎评分低于PBS组，但差异无统计学意义。胰岛素组胰岛Fas表达及凋亡β细胞率低于PBS组（P < 0.05）。胰岛素组血清IL - 4水平较高，IFN - γ水平低于PBS组（P < 0.05）。胰岛素组胰岛中I - Abeta(g7)、IFN - γ、IL - 1β和Fas mRNA转录水平以及派尔集合淋巴结中IFN - γ mRNA转录水平均低于PBS组，IL - 4、TGF - β mRNA水平高于PBS组（P < 0.05）。
特异性自身抗原胰岛素可诱导NOD小鼠产生免疫耐受并预防糖尿病，但不能阻断胰岛炎的进展。口服胰岛素可诱导调节性T细胞，使系统和胰岛中Th1向Th2细胞因子转变，从而预防Fas介导的β细胞凋亡和糖尿病。
