1,25-(OH)_2维生素D_3对NOD小鼠的免疫干预作用

Effect of 1,25-dihydroxyvitamin D_3 on immune intervention in NOD mice

目的 探讨 1,2 5 (OH) 2 维生素D3 〔1,2 5 (OH2 )D3 〕对环磷酰胺促发的NOD小鼠 1型糖尿病的预防作用。方法 取体重相近的 4周龄NOD雌性小鼠 2 0只在实验开始前均一次性腹腔注射环磷酰胺 2 80mg/kg以加速胰岛炎。分为两组 ,每组 10只 ,干预组隔日腹腔注射 1,2 5 (OH2 )D3 5 μg/kg ,对照组注射等量的花生油。 3 0天实验结束时 ,观察糖尿病发生率 ,行HE染色观察胰岛炎程度 ,免疫组化观察bcl 2 ,bax在胰岛的表达 ,流式细胞仪定量测定脾脏T淋巴细胞的凋亡率。结果 1,2 5 (OH) 2 D3 干预组糖尿病发病率较花生油对照组发病率低 ;1,2 5 (OH) 2 D3 干预后血糖值较干预前显著下降 (P <0 .0 1) ;干预组胰岛炎严重程度较花生油对照组明显减轻 ;胰岛细胞抑制凋亡的bcl 2基因的表达在 1,2 5 (OH ) 2 D3 处理组高于花生油对照组 ,而促进凋亡的bax基因的表达在 1,2 5 (OH ) 2 D3 组低于花生油对照组 (均P <0 .0 5 ) ;1,2 5 (OH ) 2 D3 组脾淋巴细胞凋亡率为 (3 2 .3 1± 7.0 1) % ,而花生油对照组凋亡率为 (2 4.19± 7.70 ) % (P <0 .0 5 )。结论 1,2 5 (OH) 2 D3 对环磷酰胺加速的NOD小鼠胰岛具有保护作用。

Objective To investigate the preventive effect of 1,25-dihydroxyvitamin D_3 〔1,25-(OH)_2D_3〕 on type 1 diabetes in cyclophosphamide-treated NOD mice. Methods Twenty female NOD mice were administered 280 mg/kg cyclophosphamide by a single intraperitoneal injection at the beginning of the experiment and then divided into two equal groups. Group 1 received intraperitoneal injection of 5 μg/kg 1,25-(OH)_2D_3 every other day; Group 2 received the intraperitoneal injection of peanut oil in the same volume as control. When the experiment was finished on the 30th day, the incidence of diabetes and the degree of insulitis were observed. The expressions of bcl-2 and bax in islets were detected with immunohistochemical technique. The apoptosis rate of spleen T lymphocyte was also measured by flow cytometry quantitative analysis. Results Intraperitoneal injections of 1,25-(OH)_2D_3 to NOD mice reduced the incidence of diabetes (10% vs 70%, P<0.05). The insulitis score and the severity of insulitis in 1,25-(OH)_2D_3-treated mice were lower than those of the control group (P<0.01). The expression of bcl-2 gene inhibiting apoptosis in islets of group 1 was higher than that in group 2, while the expression of bax gene promoting apoptosis in islets of group 1 was lower than that in group 2 (both P<0.05). The apoptosis rate of spleen lymphocyte in 1,25-(OH)_2D_3 group was higher than that of the peanut oil group 〔(32.31±7.01)% vs (24.19±7.70)%, P<0.05〕. Conclusion These results showed that 1,25-(OH)_2D_3 could prevent NOD mice from developing type 1 diabetes induced by cyclophosphamide.