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目的 了解谷氨酸脱羧酶 (GAD)对非肥胖糖尿病 (NOD)小鼠的 1型糖尿病是否具有预防作用并探讨其免疫作用机制。方法 用猪脑GAD和不完全弗氏佐剂 (FIA)混合后给 4周龄雌性NOD小鼠腹腔注射 (32例 ) ,同时单独注射等量FIA作为对照组。 8周龄时腹腔注射环磷酰胺以加速糖尿病。每周测定体重、血糖 ,糖尿病形成 2周或 2 0周龄处死小鼠后测定血清C 肽、GAD抗体(GAD Ab)和脾组织T细胞亚群 ,观察胰腺病理、免疫组化和超微结构变化。结果 2 0周龄时 ,FIA对照组的糖尿病总发病率为 73 .6 8% ,而GAD组仅为 6 .2 5 % (P <0 .0 1) ,发病时间也明显延缓 ;GAD组的胰岛炎症分数较FIA组明显降低 ,且炎症程度减轻 (P <0 .0 5 ) ;GAD组的C 肽水平也明显高于对照组 (P <0 .0 5 ) ;两组的GAD Ab阳性率无明显差别 ;FIA组的脾脏T细胞以CD+4 亚群为主 ,GAD组则CD+8亚群比例增高 ,CD4 /CD8比值显著下降 (P <0 .0 1) ;免疫组化也表明FIA组胰岛浸润淋巴细胞为CD+4 T细胞 ,而GAD组胰岛CD+4 细胞明显减少 ,且局限于胰周。结论 猪脑GAD有预防NOD小鼠胰岛炎和糖尿病发生的作用 ,其机制可能与改善小鼠缺陷的CD+8T细胞亚群有关。
Objective To investigate whether glutamate decarboxylase (GAD) has a preventive effect on type 1 diabetes in non-obese diabetic (NOD) mice and to explore its immunological mechanism. Methods Four-week-old female NOD mice were intraperitoneally injected with porcine brain GAD and incomplete Freund’s adjuvant (FIA), and intraperitoneal injection of an equal amount of FIA was performed as a control group. Cyclophosphamide was injected intraperitoneally at 8 weeks of age to speed up diabetes. Serum C-peptide, GAD antibody (GAD Ab) and T lymphocyte subsets of spleen were measured after the mice were sacrificed at 2 weeks or 20 weeks after the body weight, blood sugar and diabetes were measured every week. Pathological, immunohistochemical and ultrastructural changes of the pancreas were observed Variety. Results At 20 weeks of age, the overall incidence of diabetes in FIA control group was 73.68%, while that in GAD group was only 6.52% (P <0.01), and the onset time was also significantly delayed. In GAD group The pancreatic islet inflammation score was significantly lower than that in FIA group, and the degree of inflammation was relieved (P <0.05). The C-peptide level in GAD group was also significantly higher than that in control group (P <0.05) There was no significant difference between the two groups. T lymphocyte subsets in FIA group were predominantly CD + 4 subgroup, GAD group was higher in CD + 8 subpopulation, CD4 / CD8 ratio was significantly decreased (P <0.01), immunohistochemistry also showed The islet infiltrating lymphocytes in FIA group were CD + 4 T cells, but the number of islet CD + 4 cells in GAD group was significantly decreased, and was limited to the peripancreatic. Conclusion Pig GAD can prevent the insulitis and diabetes mellitus in NOD mice. The mechanism may be related to the improvement of mouse CD + 8 T cell subsets.