Mathews C E, Pietropaolo S L, Pietropaolo M
Department of Pediatrics, University of Pittsburgh, and Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA.
Ann N Y Acad Sci. 2003 Nov;1005:412-7. doi: 10.1196/annals.1288.070.
Type 1 diabetes (T1DM) results from a failure of central and peripheral tolerance to islet cell antigens. ICA69 belongs to a group of molecules expressed predominantly in neuroendocrine tissues (including pancreatic islets), which are targets of autoimmune responses in T1DM. These molecules are also expressed in the thymus and peripheral lymphoid organs by dendritic cells. The aim of the present study was to evaluate possible variation in thymic ICA69 expression, comparing diabetes-resistant controls to T1DM-prone NOD mice. Thymic tissue was retrieved from 3- to 6-week-old female B6, NOD-H2(b), and NOD mice. Paraffin-embedded sections were stained with an ICA69-specific antibody in an immunoperoxidase assay. ICA69 staining of thymic sections from B6 and NOD.H2(b) showed strong and continual staining, yet the sections from the NOD mice showed significantly reduced staining for ICA69. Corroboration of the reduced level of ICA69 in the thymus of NOD mice has been obtained via analysis for the expression of ICA69 versus other candidate autoantigens (glutamic acid decarboxylase 65, glutamic acid decarboxylase 67, and insulin 2) in the thymus. Real-time PCR analysis, using cDNA generated from the thymus, displayed that the expression of GAD65, GAD67, and INS2 were equivalent when comparing NOD at any age to B6, BALB/cJ, and ALR/LtJ. In marked contrast, the level of ICA69 in the thymus of the NOD mice examined was significantly reduced when compared to the controls. In fact, the real-time PCR analysis strongly suggested that ICA69 was not expressed in the thymus of NOD mice. These findings support the hypothesis that the level of thymic ICA69 expression may be of importance in regulating self-tolerance in T1DM.
1型糖尿病（T1DM）是由于中枢和外周对胰岛细胞抗原的耐受性失效所致。胰岛细胞自身抗体69（ICA69）属于一组主要在神经内分泌组织（包括胰岛）中表达的分子，而这些组织是T1DM自身免疫反应的靶标。这些分子在胸腺和外周淋巴器官中的树突状细胞中也有表达。本研究的目的是评估胸腺中ICA69表达的可能差异，将抗糖尿病对照组与易患T1DM的非肥胖糖尿病（NOD）小鼠进行比较。从3至6周龄的雌性C57BL/6（B6）小鼠、NOD-H2(b)小鼠和NOD小鼠中获取胸腺组织。石蜡包埋切片在免疫过氧化物酶测定中用ICA69特异性抗体染色。B6和NOD.H2(b)小鼠胸腺切片的ICA69染色显示为强而持续的染色，但NOD小鼠的切片显示ICA69染色明显减少。通过分析胸腺中ICA69与其他候选自身抗原（谷氨酸脱羧酶65、谷氨酸脱羧酶67和胰岛素2）的表达，证实了NOD小鼠胸腺中ICA69水平降低。使用从胸腺产生的互补DNA（cDNA）进行的实时聚合酶链反应（PCR）分析显示，在将任何年龄的NOD小鼠与B6小鼠、BALB/cJ小鼠和ALR/LtJ小鼠进行比较时，谷氨酸脱羧酶65（GAD65）、谷氨酸脱羧酶67（GAD67）和胰岛素2（INS2）的表达相当。与之形成鲜明对比的是，与对照组相比，所检测的NOD小鼠胸腺中ICA69的水平显著降低。事实上，实时PCR分析强烈表明NOD小鼠的胸腺中不表达ICA69。这些发现支持了这样一种假说，即胸腺中ICA69的表达水平可能在调节T1DM的自身耐受性方面具有重要意义。
