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目的观察视黄酸受体基因在儿童胸腺中的表达与分布,探讨其在儿童免疫系统发育中的意义。方法用地高辛素标记的反义 RNA 探针原位杂交法,测定5岁以下儿童胸腺中视黄酸受体 RARα、RARβ、RARγ,RXRαRXRβ、RXRγ6种亚型基因的表达与分布。同期的连续冰冻切片还用免疫组织化学法测定 CD1a、CD3的表达,分析视黄酸受体基因表达及分布与 T 淋巴细胞成熟的关系。并采用实时定量 RT-PCR 法对基因表达水平进行定量分析。结果原位杂交结果显示,胸腺皮质及髓质均表达 RARα、RARγmRNA,而 RXRα、RXRβ mRNA 主要在胸腺髓质表达,尤其在哈氏小体外周成熟的胸腺细胞表达较高。胸腺中不表达 RARβ、RXRγ mRNA。实时定量 RT-PCR 分析结果显示RARα、RXRαmRNA 在出生后第1年高表达,1岁后表达下降,但在1～5岁之间变化无显著差异。RARγmRNA 则随年龄增长表达增高,RXRβ mRNA 在5岁以内变化不明显。结论视黄酸受体基因在胸腺中的表达随儿童免疫系统的发育而变化,不同受体亚型基因表达水平的调节在 T 淋巴细胞的分化发育中可能具有重要意义。
Objective To observe the expression and distribution of retinoic acid receptor gene in children’s thymus and to explore its significance in the development of children’s immune system. Methods The expression and distribution of retinoic acid receptor subtypes RARα, RARβ, RARγ, RXRαRXRβ, and RXRγ in the thymus of children under 5 years of age were determined by digoxigenin-labeled antisense RNA probe in situ hybridization. The frozen sections of the same period were also detected by immunohistochemistry CD1a, CD3 expression analysis of retinoic acid receptor gene expression and distribution and T lymphocyte maturation relationship. Real-time quantitative RT-PCR was used to quantitatively analyze the gene expression level. Results In situ hybridization showed that both RARα and RARγ mRNA were expressed in the cortex and medulla of thymus, whereas RXRα and RXRβ mRNA were mainly expressed in the thymus medulla, especially in thymus. Thymus does not express RARβ, RXRγ mRNA. Real-time quantitative RT-PCR analysis showed that RARα and RXRαmRNA were highly expressed in the first year of life and decreased in the first year of life, but no significant difference was found between the ages of 1 and 5 years. The expression of RARγmRNA increased with age, and the expression of RXRβ mRNA did not change significantly after 5 years of age. Conclusion The expression of retinoic acid receptor gene in thymus varies with the development of children’s immune system. The regulation of the expression of different receptor subtypes may play an important role in the differentiation and development of T lymphocytes.