Sanz J M, Di Virgilio F
Department of Experimental and Diagnostic Medicine, Section of General Pathology, and Center of Biotechnology, University of Ferrara, Ferrara, Italy.
J Immunol. 2000 May 1;164(9):4893-8. doi: 10.4049/jimmunol.164.9.4893.
Endotoxin-dependent release of IL-1 beta from mouse microglial cells is a very inefficient process, as it is slow and leads to accumulation of a modest amount of extracellular cytokine. Furthermore, secreted IL-1 beta is mostly in the procytokine unprocessed form. Addition of extracellular ATP to LPS-primed microglia caused a burst of release of a large amount of processed IL-1 beta. ATP had no effect on the accumulation of intracellular pro-IL-1 beta in the absence of LPS. In LPS-treated cells, ATP slightly increased the synthesis of pro-IL-1 beta. Optimal ATP concentration for IL-1 beta secretion was between 3 and 5 mM, but significant release could be observed at concentrations as low as 1 mM. At all ATP concentrations IL-1 beta release could be inhibited by increasing the extracellular K+ concentration. ATP-dependent IL-1 beta release was also inhibited by 90 and 60% by the caspase inhibitors YVAD and DEVD, respectively. Accordingly, in ATP-stimulated microglia, the p20 proteolytic fragment derived from activation of the IL-1-beta-converting enzyme could be detected by immunoblot analysis. These experiments show that in mouse microglial cells extracellular ATP triggers fast maturation and release of intracellularly accumulated IL-beta by activating the IL-1-beta-converting enzyme/caspase 1.
内毒素依赖的小鼠小胶质细胞释放白细胞介素-1β是一个非常低效的过程，因为它很缓慢，且导致少量细胞外细胞因子的积累。此外，分泌的白细胞介素-1β大多处于前细胞因子的未加工形式。向脂多糖预处理的小胶质细胞中添加细胞外ATP会导致大量加工后的白细胞介素-1β的爆发性释放。在没有脂多糖的情况下，ATP对细胞内白细胞介素-1β前体的积累没有影响。在脂多糖处理的细胞中，ATP略微增加了白细胞介素-1β前体的合成。白细胞介素-1β分泌的最佳ATP浓度在3至5 mM之间，但在低至1 mM的浓度下也可观察到显著释放。在所有ATP浓度下，增加细胞外钾离子浓度均可抑制白细胞介素-1β的释放。半胱天冬酶抑制剂YVAD和DEVD分别使ATP依赖的白细胞介素-1β释放抑制90%和60%。因此，在ATP刺激的小胶质细胞中，通过免疫印迹分析可以检测到源自白细胞介素-1β转换酶激活的p20蛋白水解片段。这些实验表明，在小鼠小胶质细胞中，细胞外ATP通过激活白细胞介素-1β转换酶/半胱天冬酶1触发细胞内积累的白细胞介素-β的快速成熟和释放。
