Saï P, Damagé C, Rivereau A S, Hoeltzel A, Gouin E
Laboratory of Cellular and Molecular Immuno-Endocrinology, INRA/ENVN, University School of Medicine, Nantes, France.
J Autoimmun. 1996 Dec;9(6):713-22. doi: 10.1006/jaut.1996.0093.
Nonobese diabetic (NOD) mice develop an autoimmune disease with a long prodromal period and constitute a model for investigating the prevention of human type 1 diabetes. Since prophylactic insulin injections reduced the incidence of diabetes in NOD mice, we tested a new prophylactic strategy to prevent diabetes in NOD mice consisting of oral administration of insulin, protected in polyalkylcyanoacrylate nanocapsules from degradation in the gastrointestinal tract. In humans, this form of prophylactic insulin administration would be less constraining than insulin injections. Ninety female NOD mice were randomized at weaning and fed once a week (from 60 to 300 days of age) with insulin nanocapsules (100 U/kg) or empty nanocapsules. Within the group fed with insulin nanocapsules, the incidence of diabetes was reduced (38% vs 75%; P < 0.02), the onset of disease was delayed (P < 0.02), and the severity of lymphocytic inflammation of endogenous islets was reduced (P < 0.03). Although the oral treatment was stopped at 300 days of age, the incidence of diabetes at 360 days remained lower in mice previously fed insulin nanocapsules (P < 0.02). Previous feedings with insulin nanocapsules did not protect against cyclophosphamide-induced diabetes, since final incidence of diabetes (sum of the incidence during the initial 360 days and the further CY-induced incidence) reached the final incidence obtained in mice previously fed empty nanocapsules and treated with cyclophosphamide. Intestinal absorption of insulin nanocapsules was evidenced by HPLC separation of human insulin in NOD sera. During cotransfer, T splenocytes from mice fed insulin nanocapsules were able to reduce the capacity of T cells from diabetic donors to adoptively transfer the disease (P < 0.01). Antigens for islet-cell autoantibodies (ICA) in pancreata from both NOD groups were compared by immunofluorescence with the same ICA-positive human sera to ensure that differences were due to quantitative changes in antigen. These antigens, which could serve as an index of a possibly more extended antigen beta-cell rest, were decreased (P < 0.02) and pancreatic insulin content was reduced (P < 0.05) in mice fed with insulin nanocapsules, suggesting a mechanism of 'beta cell rest'. To summarize, early feeding with insulin nanocapsules reduces diabetes and insulitis in the NOD mouse model that mimics human type 1 diabetes. This may be due both to generation of cellular mechanisms that actively suppress disease and a decrease in antigens which makes beta cells less vulnerable to autoimmune aggression.
非肥胖糖尿病（NOD）小鼠会发展出一种前驱期较长的自身免疫性疾病，是研究人类1型糖尿病预防的模型。由于预防性注射胰岛素可降低NOD小鼠患糖尿病的几率，我们测试了一种新的预防策略来防止NOD小鼠患糖尿病，该策略为口服包裹于聚烷基氰基丙烯酸酯纳米胶囊中以防止在胃肠道中降解的胰岛素。在人类中，这种预防性胰岛素给药方式比注射胰岛素的限制更少。90只雌性NOD小鼠在断奶时随机分组，每周喂食一次（60至300日龄）胰岛素纳米胶囊（100 U/kg）或空纳米胶囊。在喂食胰岛素纳米胶囊的组中，糖尿病发病率降低（38%对75%；P<0.02），疾病发作延迟（P<0.02），内源性胰岛淋巴细胞炎症的严重程度降低（P<0.03）。尽管口服治疗在300日龄时停止，但在360日龄时，先前喂食胰岛素纳米胶囊的小鼠患糖尿病的几率仍然较低（P<0.02）。先前喂食胰岛素纳米胶囊并不能预防环磷酰胺诱导的糖尿病，因为糖尿病的最终发病率（最初360天期间的发病率与环磷酰胺诱导的进一步发病率之和）达到了先前喂食空纳米胶囊并用环磷酰胺治疗的小鼠所获得的最终发病率。通过高效液相色谱法分离NOD血清中的人胰岛素，证明了胰岛素纳米胶囊的肠道吸收。在共转移过程中，来自喂食胰岛素纳米胶囊的小鼠的T脾细胞能够降低糖尿病供体T细胞过继转移疾病的能力（P<0.01）。通过免疫荧光将两个NOD组胰腺中胰岛细胞自身抗体（ICA）的抗原与相同的ICA阳性人血清进行比较，以确保差异是由于抗原的定量变化所致。这些抗原可作为可能更广泛的抗原β细胞静止的指标，在喂食胰岛素纳米胶囊的小鼠中减少（P<0.02），胰腺胰岛素含量降低（P<0.05），提示存在“β细胞静止”机制。总之，在模仿人类1型糖尿病的NOD小鼠模型中，早期喂食胰岛素纳米胶囊可降低糖尿病和胰岛炎的发生率。这可能是由于产生了积极抑制疾病的细胞机制以及抗原减少，使β细胞更不易受到自身免疫攻击。
