创伤后IL-2表达受抑与核转录因子NFAT变化的关系

THE DECLINE IN THE INDUCTION OF IL-2 EXPRESSION AFTER TRAUMA IS CORRELA TED TO CHANGES IN THE TRANSCRIPTION FACTOR NFAT

为探讨创伤后脾细胞核转录因子 (nuclearfactorofactivatedT cells,NFAT)的DNA结合活性变化和IL 2表达受抑间的关系 ,采用小鼠双后肢闭合性砸伤 +骨折模型 ,于创伤后 12h及 1、4、7、10、14天处死动物 ,分离脾细胞 ,经ConA刺激细胞后收集培养上清以测定IL 2活性 ;提取脾细胞RNA以测定IL 2mRNA ;提取脾细胞核蛋白 ,用电泳迁移率改变试验 (electrophoreticmobilityshiftassay ,EMSA)检测NFAT的DNA结合活性。结果显示 ,创伤后脾细胞NFAT的DNA结合活性逐渐下降 ,至伤后 4天时下降最明显 ,仅为正常对照组的 41%。这与创伤后IL 2活性和IL 2mRNA的降低相一致。结果表明 ,创伤后IL 2表达受抑至少部分是由于NFAT的DNA结合活性降低所致。这对于阐明创伤后IL 2受抑的机制具有重要意义。

This study was designed to determine if the decrease in the expression of interleukin 2(IL 2) in spleen lymphocytes after trauma was associated with the changes in the transcription factor NFAT binding activity. Closed impact injury with fracture of both hind limbs in mice was adopted as the trauma model. Animals were sacrificed at the 12h and 1,4,7,10,14 days after injury. Spleen lymphocytes were isolated from traumatized mice and stimulated with concanavalin A, The culture supernatants were harvested and assayed for IL 2 activity. Total RNA was extracted from spleen lymphocytes and assayed for IL 2 mRNA. Nuclear protein was extracted,and DNA binding activity of NFAT was measured using an electrophoretic mobility shift assay(EMSA). The results showed that the DNA binding activity of NFAT gradually decreased , with trough value of NFAT binding activity ,accounting for 41% of the control, observed at 4d after injury. It was closely associated with the decline of IL 2 activity and IL 2 mRNA. These data suggest that the decline in the induction of IL 2 expression is,at least, partially due to the impairment in the activation of NFAT in traumatized mice. Taken together, the results are significant to clarify the mechanism of the decline in the induction of IL 2 expression after trauma.