O'Brien B A, Harmon B V, Cameron D P, Allan D J
School of Life Science, Queensland University of Technology, Brisbane, Australia.
Diabetes. 1997 May;46(5):750-7. doi: 10.2337/diab.46.5.750.
The NOD/Lt mouse, a widely used model of human autoimmune IDDM, was used to establish the mode of beta-cell death responsible for the development of IDDM. Apoptotic cells were present within the islets of Langerhans in hematoxylin and eosin-stained sections of pancreases harvested from 3- to 18-week-old female NOD/Lt mice (a range of 11-50 apoptotic cells per 100 islets). Immunohistochemical localization of insulin to the dying cells confirmed the beta-cell origin of the apoptosis. Although some islets from age-matched control female NOD/scid mice contained apoptotic cells, virtually all of these cells were insulin negative as determined by immunohistochemistry. The small number of apoptotic insulin-positive cells identified in islets from NOD/scid mice (a range of 0-1 apoptotic cells per 100 islets) was not statistically significant, compared with the numbers recorded in NOD/Lt mice. All dying cells showed the morphological changes characteristic of cell death by apoptosis and stained positively with the TUNEL method for end-labeling DNA strand breaks. The maximum mean amount of beta-cell apoptosis occurring in NOD/Lt mice was at week 15 (50 apoptotic cells per 100 islets), which coincided with the earliest onset of diabetes as determined by blood glucose, urine glucose, and pancreatic immunoreactive insulin measurements. While there was no peak incidence of beta-cell apoptosis throughout the time period studied (weeks 3-18), the incidence of apoptosis decreased at week 18, by which time 50% of the animals had overt diabetes. The low levels of beta-cell apoptosis observed is indicative of a gradual deletion of the beta-cell population throughout the extensive preclinical period seen in this model and would be sufficient to account for the beta-cell loss resulting in IDDM. Apoptosis of beta-cells preceded the appearance of T-cells (CD3-positive by immunohistochemistry) in islets. Lymphocytic infiltration of islets (insulitis) was not detected until week 6. The results show that beta-cell apoptosis is responsible for the development of IDDM in the NOD/Lt mouse and that its onset precedes lymphocytic infiltration of the islets.
非肥胖糖尿病/近交系（NOD/Lt）小鼠是一种广泛应用的人类自身免疫性胰岛素依赖型糖尿病（IDDM）模型，被用于确定导致IDDM发生的β细胞死亡模式。在取自3至18周龄雌性NOD/Lt小鼠的胰腺苏木精-伊红染色切片中，胰岛内存在凋亡细胞（每100个胰岛中有11至50个凋亡细胞）。胰岛素在死亡细胞中的免疫组化定位证实了凋亡细胞起源于β细胞。尽管年龄匹配的对照雌性NOD/scid小鼠的一些胰岛含有凋亡细胞，但通过免疫组化确定，几乎所有这些细胞胰岛素均呈阴性。与NOD/Lt小鼠记录的数量相比，在NOD/scid小鼠胰岛中鉴定出的少量凋亡胰岛素阳性细胞（每100个胰岛中有0至1个凋亡细胞）无统计学意义。所有死亡细胞均表现出凋亡所致细胞死亡的形态学变化，且用TUNEL法进行DNA链断裂末端标记时呈阳性染色。NOD/Lt小鼠中发生的β细胞凋亡的最大平均数量出现在第15周（每100个胰岛中有50个凋亡细胞），这与通过血糖、尿糖和胰腺免疫反应性胰岛素测量确定的糖尿病最早发病时间一致。虽然在所研究的时间段（第3至18周）内β细胞凋亡没有出现峰值发生率，但在第18周时凋亡发生率下降，此时50%的动物已出现明显糖尿病。观察到的β细胞凋亡水平较低表明在该模型所见的整个广泛临床前期β细胞群体逐渐缺失，这足以解释导致IDDM的β细胞损失。β细胞凋亡先于胰岛中T细胞（免疫组化显示CD3阳性）的出现。直到第6周才检测到胰岛的淋巴细胞浸润（胰岛炎）。结果表明，β细胞凋亡是NOD/Lt小鼠中IDDM发生的原因，且其发生先于胰岛的淋巴细胞浸润。
