Background: Previous work revealed the existence of a severe thymic atrophy with massive loss of immature CD4⁺CD8⁺ thymocytes in animals developing insulin-dependent diabetes, chemically induced by alloxan. Furthermore, the intrathymic expression of chemokines, such as CXCL12, is changed in these animals, suggesting that cell migration-related patterns may be altered. One molecular interaction involved in normal thymocyte migration is that mediated by soluble semaphorin-3A and its cognate receptor neuropilin-1. Objectives: We investigated herein the expression and role of semaphorin-3A in the migratory responses of thymocytes from alloxan-induced diabetic mice. We characterized semaphorin-3A and its receptor, neuropilin-1, in thymuses from control and diabetic mice as well as semaphorin-3A-dependent migration of developing thymocytes in both control and diabetic animals. Methods: Diabetes was chemically induced after a single injection of alloxan in young adult BALB/c mice. Thymocytes were excised from control and diabetic individuals and subjected to cytofluorometry for simultaneous detection of semaphorin-3A or neuropilin-1 in CD4/CD8-defined subsets. Cell migration in response to semaphorin-3A was performed using cell migration transwell chambers. Results: Confirming previous data, we observed a severe decrease in the total numbers of thymocytes in diabetic mice, which comprised alterations in both immature (double-negative subpopulations) and mature CD4/CD8-defined thymocyte subsets. These were accompanied by a decrease in the absolute numbers of semaphorin-3A-bearing thymocytes, comprising CD4^–CD8^–, CD4⁺CD8⁺, and CD4^–CD8⁺ cells. Additionally, immature CD4^–CD8^– and CD4⁺CD8⁺ developing T cells exhibited a decrease in the membrane density of semaphorin-3A. The relative and absolute numbers of neuropilin-1-positive thymocytes were also decreased in diabetic mouse thymocytes compared to controls, as seen in CD4^–CD8^–, CD4⁺CD8⁺, and CD4^–CD8⁺ cell subpopulations. Functionally, we observed a decrease in the chemorepulsive role of semaphorin-3A, as revealed by transwell migration chambers. Such an effect was seen in all immature and mature thymocyte subsets. Conclusions: Taken together, our data clearly unravel a disruption in the normal cell migration pattern of developing thymocytes following chemically induced insulin-dependent diabetes, as ascertained by the altered migratory response to sempahorin-3A. In conceptual terms, it is plausible to think that such disturbances in the migration pattern of thymocytes from these diabetic animals may exert an impact in the cell-mediated immune response of these mice.
Neuroimmunomodulation

中文翻译：

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Semaphorin-3A相关的化学诱导的糖尿病小鼠胸腺细胞迁移的减少。

背景：先前的研究表明，在由四氧嘧啶化学诱导的胰岛素依赖型糖尿病动物中，存在严重的胸腺萎缩，未成熟的CD4 ⁺ CD8 ⁺胸腺细胞大量丢失。此外，这些动物体内趋化因子（如CXCL12）的胸腺内表达发生了改变，表明细胞迁移相关模式可能会改变。正常胸腺细胞迁移涉及的一种分子相互作用是由可溶性semaphorin-3A及其同源受体Neuropilin-1介导的。目标：我们在这里研究了信号量3A在四氧嘧啶诱导的糖尿病小鼠的胸腺细胞迁移反应中的表达和作用。我们在对照和糖尿病小鼠的胸腺中以及在对照和糖尿病动物中发育中的胸腺细胞中依赖semaphorin-3A的迁移中表征了semaphorin-3A及其受体neuropilin-1。方法：单次注射四氧嘧啶对成年BALB / c小鼠进行化学诱导。从对照和糖尿病个体中切除胸腺细胞，并进行细胞荧光分析，以同时检测CD4 / CD8定义的亚群中的semaphorin-3A或neuropilin-1。使用细胞迁移transwell室进行响应semaphorin-3A的细胞迁移。结果：证实先前的数据，我们观察到糖尿病小鼠胸腺细胞总数的严重减少，这包括未成熟（双阴性亚群）和成熟的CD4 / CD8定义的胸腺细胞亚群的改变。这些伴随着带有信号信使蛋白3A的胸腺细胞的绝对数量减少，包括CD4 ^– CD8 ^–，CD4 ⁺ CD8 ⁺和CD4 ^– CD8 ⁺细胞。此外，未成熟的CD4 ^– CD8 ^–和CD4 ⁺ CD8 ⁺发育中的T细胞的Semaphorin-3A膜密度降低。在CD4 ^– CD8 ^–，CD4 ⁺ CD8 ⁺和CD4 ^– CD8 ⁺细胞亚群中，与对照组相比，糖尿病小鼠胸腺细胞中神经pilin-1阳性胸腺细胞的相对和绝对数目也减少了。在功能上，我们观察到了semaphorin-3A在化学脉冲作用方面的降低，如transwell迁移室所揭示。在所有未成熟和成熟的胸腺细胞亚群中都可以看到这种效果。结论：综上所述，我们的数据清楚地揭示了化学诱导的胰岛素依赖型糖尿病后胸腺细胞正常细胞迁移模式的破坏，这可以通过对Sempahorin-3A的迁徙反应改变来确定。从概念上讲，可以认为来自这些糖尿病动物的胸腺细胞迁移模式的这种紊乱可能会对这些小鼠的细胞介导的免疫反应产生影响。
神经免疫调节