重组人胰岛素生长因子-1对非肥胖糖尿病小鼠Ⅰ型糖尿病的预防作用

Recombinant human IGF-1 prevents type 1 diabetes in female non-obese diabetic mice

目的 了解早期应用重组人胰岛素生长因子 1(rhIGF 1)对非肥胖糖尿病 (NOD)小鼠糖尿病发病的影响 ,并探讨其对细胞和体液免疫的影响。方法 将 4周龄雌性NOD小鼠随机分为 2组 :rhIGF 1组 (n =10 ) :腹腔注射rhIGF 137 5 μg·kg-1·d-12周 ;对照组 (n =10 ) :注射等体积生理盐水 2周。每周测体重、血糖 ,鼠龄 40周处死小鼠 ,测定血清C 肽和谷氨酸脱羧酶抗体 ,同时观察胰岛病理、免疫组化和脾脏T细胞亚群变化。结果 rhIGF 1组的糖尿病发病率 40 % ,明显低于对照组 ,发病时间也显著延缓 ;残存的胰岛数目亦明显高于对照组 ,且胰岛炎程度减轻 ,脾CD+4 T细胞亚群比例较对照组下降 ,CD8亚群显著增加 ;胰岛浸润CD+4 T细胞数量减少且局限在胰周。两组谷氨酸脱羧酶抗体阳性率之间差异无显著性意义。结论 rhIGF 1对NOD小鼠糖尿病发病有预防和延缓作用 ,其机制可能与提高小鼠缺陷的CD+8T细胞亚群、调节CD4 /CD8平衡和限制CD4 亚群向胰岛汇集有关。

Objectives To study whether recombinant human (rhIGF-1) can prevent the onset of type 1 di abetes in female non-obese diabetic (NOD) mice, and its influence on their immune system. Methods Ten mice were injected intraperitonally (ip) rhIGF-1 37.5 μg·kg -1 ·d -1 at 4 weeks old for 2 weeks as tr eated group; and the same volume of normal solution (NS) was used in 10 mice as control group. All mice were killed at 40 weeks old or 2 weeks after the diagnos is of diabetes. Blood glucose of t ail vein blood was measured weekly using a glucometer. At the end of the experi m ent, serum C-peptide levels and antibodies to glutamic acid decarboxylase (GAD) were detected with RIA and ELISA methods, respectively. T cell subsets of splee n were undertaken two-color FACS analysis using Cy-chrome anti-CD 4 and FITC -anti- CD 8 monoclonal antibodies; pancreatic histopathology and immunohistochemistry of T cell were conducted. Results Treatment with rhIGF-1 at 4 weeks old reduced th e total incidence of diabetes (40% vs 90%, P< 0 05) and delay its onset ［(26 25±3 68) weeks vs (21 6±6 7) weeks］ compared with control group ( P< 0 05). RhIGF-1 show ed the growth effect on NOD mice, because the wet weight of spleen and pancreas of groups treated with rhIGF-1 were higher than that of control mice ( P< 0 01, res pectively). Only 3 24 (0 92 islets/mouse) was observed in the control group a t d eath, but they increased to 13 2 (3 14 islets/mouse) in the rhIGF-1 group. T he i nsulitis score decreased from 0 738±0 194 to 0 098±0 035 in the later group. A marked reduction of insulitis serverity of pancreatic glands was also observed . A strong proliferative response of CD + 8T subsets in splenocytes occurred in rhI GF-1 treated mice, and the imbalance of CD + 4/CD + 8 subgroup in control m ice (2 03 ±0 72) was orrected in the later group (0 53±0 22, respectively, P < 0 01). The l ymphocytes infiltrating islets in the rhIGF-1 group showed a reduction of CD + 4 cells, and they existed only outside of islets. Conclusions WTBZ These data monstrated the preventive effects of rhtIGF-1 on the onset of type 1 diabetes and the seve r ity of insulitis in female NOD mice. The mechanisms of these effects may be rel a ted to the induction of a CD + 8 Ts cell response that inhibits the spontaneou s de velopment of autoreactive CD + 4 T subsets response, or inhibiting the homing of CD + 4 T cells to islets.