Women's Reproductive Health Laboratory of Zhejiang Province, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China.
PLoS One. 2012;7(5):e36413. doi: 10.1371/journal.pone.0036413. Epub 2012 May 1.
Mifepristone (RU486), a potent antagonist of progesterone and glucocorticoids, is involved in immune regulation. Our previous studies demonstrated that mifepristone directly augments the cytotoxicity of human uterine natural killer (uNK) cells. However, the mechanism responsible for this increase in cytotoxicity is not known. Here, we explored whether the increased cytotoxicity in uNK cells produced by mifepristone is due to either anti-progesterone or anti-glucocorticoid activity, and also investigated relevant changes in the mitogen-activated protein kinase (MAPK) pathway.
METHODOLOGY/PRINCIPAL FINDINGS: Uterine NK cells were isolated from decidual samples and incubated with different concentrations of progesterone, cortisol, or mifepristone. The cytotoxicity and perforin expression of uNK cells were detected by mitochondrial lactate dehydrogenase-based MTS staining and flow cytometry assays, respectively. Phosphorylation of components of the MAPK signaling pathway was detected by Western blot. Cortisol attenuated uNK cell-mediated cytotoxicity in a concentration-dependent manner whereas progesterone had no effect. Mifepristone alone increased the cytotoxicity and perforin expression of uNK cells; these effects were blocked by cortisol. Furthermore, mifepristone increased the phosphorylation of ERK1/2 in a cortisol-reversible manner. Specific ERK1/2 inhibitor PD98059 or U0126 blocked cortisol- and mifepristone-induced responses in uNK cells.
CONCLUSIONS/SIGNIFICANCE: These results suggest that mifepristone acts as a glucocorticoid antagonist to augment uNK cell-mediated cytotoxicity via ERK activation, which may be caused by increased perforin expression. These observations may reveal an important mechanism by which mifepristone upregulates the cytotoxicity of uNK cells.
米非司酮（RU486）是一种强效的孕激素和糖皮质激素拮抗剂，参与免疫调节。我们之前的研究表明，米非司酮直接增强了人子宫自然杀伤（uNK）细胞的细胞毒性。然而，导致这种细胞毒性增加的机制尚不清楚。在这里，我们探讨了米非司酮是否通过抗孕激素或抗糖皮质激素活性导致 uNK 细胞的细胞毒性增加，并研究了丝裂原活化蛋白激酶（MAPK）通路的相关变化。
方法/主要发现：从蜕膜样本中分离出子宫 NK 细胞，并与不同浓度的孕激素、皮质醇或米非司酮孵育。通过线粒体乳酸脱氢酶（MTS）染色和流式细胞术检测 uNK 细胞的细胞毒性和穿孔素表达。通过 Western blot 检测 MAPK 信号通路各成分的磷酸化。皮质醇以浓度依赖性方式减弱 uNK 细胞介导的细胞毒性，而孕激素则没有影响。米非司酮单独增加 uNK 细胞的细胞毒性和穿孔素表达；这些作用被皮质醇阻断。此外，米非司酮以皮质醇可逆的方式增加 ERK1/2 的磷酸化。特异性 ERK1/2 抑制剂 PD98059 或 U0126 阻断了皮质醇和米非司酮诱导的 uNK 细胞反应。
结论/意义：这些结果表明，米非司酮作为一种糖皮质激素拮抗剂，通过 ERK 激活增强 uNK 细胞介导的细胞毒性，这可能是由于穿孔素表达增加所致。这些观察结果可能揭示了米非司酮上调 uNK 细胞细胞毒性的一个重要机制。
