p38-MAPK/NF-κB活化导致免疫性血小板减少症糖皮质激素抵抗机制研究

Glucocorticoids (GC) are the first choice for patients with immune thrombocytopenia (ITP). However, around 30% of the patients fail to respond to GC, which is called GC resistance. Until now, there is not any effective treatment and prevention measure for such resistance. Therefore, in order to improve the therapeutic efficacy, it is significant to seek effective ways to overcome the resistance. In the preliminary investigations, we measured the mRNA expression of GR isoforms (GRα, GRβ, GRγ, GRP) in peripheral blood mononuclear cells (PBMC) from patients with ITP. The proteins of GRα ,GRβ, nuclear factor-κB (NF-κB), and activator protein-1 (AP-1) were detected by western blot. Our results firstly indicated that low expression of GRα and high expression of p65/NF-κB correlated with GC resistance in ITP patients. The aim of our project is to investigate the upstream factor of NF-κB activation and the mechanism of decreased expression of GRα through NF-κB activation in GC resistanat patients with ITP. The correlation between p38 MAPK signal pathway and NF-κB will be explored to confirm the mechaism of the NF-κB activation; GRα-NF-κB association will be detected to verify the direct effect of NF-κB on inhibiting the transcriptional activity of GRα. Meanwhile, we will explore whether GRα is phosphorylated by p38 MAPK and the subsequent degradation via the ubiquitin-proteasomal pathway. In vitro, the p38 inhibitor and p65 small interfering RNA (siRNA) will be used to block the activity of p38 MAPK and NF-κB. Then the recovery of the expression of GRα will be observed. Altogether, we seek to clarify the mechaism of GC resistance in patients with ITP through the function of NF-κB-GRα interaction and posttranslational protein modification. Furthermore, p38-MAPK/NF-κB pathway may be a reasonable therapeutic target to overcome GC resistance in patients with ITP.

糖皮质激素(GC)是治疗免疫性血小板减少症(ITP)的首选药物，约30%治疗无效，称为GC抵抗，目前尚无解决方法，故寻找克服抵抗方法是提高该重症疗效的有效途径。申请人首次报道：ITP抵抗者GC受体α(GRα)低表达，NF-κB高活化，推测上述异常与抵抗密切相关。本课题拟深入研究ITP患者GC抵抗NF-κB活化的上游因素及NF-κB活化导致GRα减少的机制。探讨p38 MAPK通路与NF-κB活化相关性，阐明NF-κB活化机制；检测NF-κB-GRα复合物，明确NF-κB对GRα的直接作用；同时探索p38激活致GRα磷酸化而被蛋白酶体降解的可能性；体外阻断p38和NF-κB表达，验证其对GRα表达的恢复作用。通过研究阐明GRα表达、核蛋白与受体蛋白相互作用及翻译后修饰在GC抵抗中作用机制，为p38-MAPK/NF-κB通路作为逆转GC抵抗靶点提供依据，从而提出克服ITP患者GC抵抗的新思路。

糖皮质激素(GC)是治疗免疫性血小板减少症(ITP)的首选药物，约30%治疗无效，称为GC抵抗，目前尚无解决方法，故寻找克服抵抗方法是提高该重症疗效的有效途径。申请人首次报道： ITP抵抗者GC受体α(GRα)低表达，NF-κB高活化，推测上述异常与抵抗密切相关。本课题深入研究了ITP患者GC抵抗NF-κB活化的上游因素及NF-κB活化导致GRα减少的机制，探讨了p38 MAPK通路与NF-κB活化相关性，阐明了NF-κB活化机制；检测NF-κB-GRα复合物，明确NF-κB对GRα的直接作用以及p38激活致GRα磷酸化而被蛋白酶体降解的机制；体外阻断p38和NF-κB表达，证实了其对GRα表达的恢复作用。通过研究阐明了GRα表达、核蛋白与受体蛋白相互作用及翻译后修饰在GC抵抗中的作用机制，为p38-MAPK/NF-κB通路作为逆转GC抵抗靶点提供依据，提出了克服ITP患者GC抵抗的新思路。