ABSTRACT

Background

The thymus is responsible for thymocyte differentiation into immunocompetent T lymphocytes. Different cell types in the thymic microenvironment actively cooperate in this process, interacting with the developing thymocytes through soluble factors, extracellular matrix (ECM) molecules, and receptors. In addition, this microenvironment can be influenced by several factors, such as semaphorin-3A (Sema3A), which is a multifunctional protein involved in cell migration. We evaluated the Sema3A effects on the cellular parameters and functional features of thymic stromal cells.

Methods

Thymic stromal cells were obtained by enzymatic digestion of the murine thymus. These cells were treated with Sema3A and evaluated as follows: cell morphology by scanning electron microscope, F-actin cytoskeleton and deposition of ECM molecules by fluorescence microscopy, and adhesion assays with freshly obtained thymocytes.

Results

The obtained thymic stroma was composed of 67% of thymic epithelial cells (TECs), and 90% of the TECs were positive for the Sema3A receptor neuropilin-1. These cells secreted CXCL12, IL-7 and extended thymocyte survival. Sema3A changed the morphology of thymic stromal cells and promoted F-actin reorganization. In addition, the fibronectin fibers were reoriented, and the laminin production was increased in Sema3A-treated thymic stromal cells. In the adhesion assays, there was an increase in the number of adhered thymocytes when thymic stromal cells were pretreated with Sema3A.

Conclusion

Our data strongly suggest the active participation of Sema3A in thymic physiology, highlighting its role as an immunomodulatory molecule. This may provide important knowledge for understanding the interactions of thymic cells.

中文翻译：

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胸腺基质细胞对 semaphorin-3A 的反应

摘要

背景

胸腺负责将胸腺细胞分化为免疫活性 T 淋巴细胞。胸腺微环境中的不同细胞类型在此过程中积极合作，通过可溶性因子、细胞外基质 (ECM) 分子和受体与发育中的胸腺细胞相互作用。此外，这种微环境会受到多种因素的影响，例如信号素 3A (Sema3A)，它是一种参与细胞迁移的多功能蛋白。我们评估了 Sema3A 对胸腺基质细胞的细胞参数和功能特征的影响。

方法

通过小鼠胸腺的酶消化获得胸腺基质细胞。用 Sema3A 处理这些细胞并评估如下：扫描电子显微镜下的细胞形态，荧光显微镜下的 F-肌动蛋白细胞骨架和 ECM 分子的沉积，以及新鲜获得的胸腺细胞的粘附试验。

结果

获得的胸腺基质由67%的胸腺上皮细胞（TECs）组成，90%的TECs对Sema3A受体neuropilin-1呈阳性。这些细胞分泌 CXCL12、IL-7 并延长胸腺细胞的存活时间。Sema3A 改变胸腺基质细胞的形态并促进 F-肌动蛋白重组。此外，纤连蛋白纤维被重新定向，并且在 Sema3A 处理的胸腺基质细胞中层粘连蛋白的产生增加。在粘附试验中，当胸腺基质细胞用 Sema3A 预处理时，粘附的胸腺细胞数量增加。

结论

我们的数据强烈表明 Sema3A 积极参与胸腺生理学，突出了其作为免疫调节分子的作用。这可能为理解胸腺细胞的相互作用提供重要的知识。