Irusen Elvis, Matthews John G, Takahashi Atsushi, Barnes Peter J, Chung Kian F, Adcock Ian M
Thoracic Medicine, Imperial College School of Medicine at the National Heart and Lung Institute, London, United Kingdom.
J Allergy Clin Immunol. 2002 Apr;109(4):649-57. doi: 10.1067/mai.2002.122465.
Although glucocorticoids are the most effective treatment for chronic inflammatory diseases, such as asthma, some patients show a poor response. IL-2 combined with IL-4 can alter glucocorticoid receptor (GR) ligand-binding affinity and modulate glucocorticoid function.
We sought to confirm the altered ligand-binding affinity in a distinct group of steroid-dependent asthmatic subjects and examine the mechanism by which IL-2 and IL-4 modify the ligand-binding affinity of the GR.
We examined PBMCs from healthy subjects, subjects with mild asthma, and steroid-dependent subjects with severe asthma using dexamethasone-binding assays and Western blot analysis of GR and phosphorylated activated transcription factor 2 expression. GR phosphorylation was measured after orthophosphate labeling and immunoprecipitation and cytokine production by means of ELISA.
GR ligand-binding affinity was reduced in the nucleus but not in the cytoplasm of steroid-dependent asthmatic subjects compared with that seen in healthy subjects (dissociation constant, 39.8 +/- 4.6 vs. 6.79 +/- 0.8 nmol/L). This difference in ligand-binding affinity could be mimicked by IL-2 and IL-4 cotreatment and was blocked by the p38 mitogen-activated kinase (MAPK) inhibitor SB203580. Activation of p38 MAPK by IL-2 and IL-4, as shown by means of phosphorylation of activated transcription factor 2, resulted in GR phosphorylation and reduced dexamethasone repression of LPS-stimulated GM-CSF release. p38 MAPK phosphorylation of CD2(+) T cells occurred on serine residues. The ability of dexamethasone to modulate IL-10 release was also inhibited by IL-2 and IL-4 cotreatment. These effects were also inhibited by SB203580.
These data show that p38 MAPK inhibitors may have potential in reversing glucocorticoid insensitivity and reestablishing the beneficial effects of glucocorticoids in patients with severe asthma.
尽管糖皮质激素是治疗慢性炎症性疾病（如哮喘）最有效的药物，但一些患者反应不佳。白细胞介素-2（IL-2）联合白细胞介素-4（IL-4）可改变糖皮质激素受体（GR）的配体结合亲和力并调节糖皮质激素功能。
我们试图在一组独特的类固醇依赖型哮喘患者中证实配体结合亲和力的改变，并研究IL-2和IL-4改变GR配体结合亲和力的机制。
我们使用地塞米松结合试验以及GR和磷酸化激活转录因子2表达的蛋白质印迹分析，检测了健康受试者、轻度哮喘患者以及类固醇依赖型重度哮喘患者的外周血单核细胞（PBMC）。通过正磷酸盐标记、免疫沉淀以及酶联免疫吸附测定法（ELISA）检测细胞因子产生后，测量GR磷酸化水平。
与健康受试者相比，类固醇依赖型哮喘患者细胞核中的GR配体结合亲和力降低，但细胞质中的未降低（解离常数分别为39.8±4.6和6.79±0.8 nmol/L）。IL-2和IL-4联合处理可模拟这种配体结合亲和力的差异，而p38丝裂原活化蛋白激酶（MAPK）抑制剂SB203580可阻断这种差异。如通过激活转录因子2的磷酸化所示，IL-2和IL-4激活p38 MAPK导致GR磷酸化，并降低地塞米松对脂多糖（LPS）刺激的粒细胞-巨噬细胞集落刺激因子（GM-CSF）释放的抑制作用。CD2(+) T细胞的p38 MAPK磷酸化发生在丝氨酸残基上。IL-2和IL-4联合处理也抑制了地塞米松调节白细胞介素-10释放的能力。这些作用也被SB203580抑制。
这些数据表明，p38 MAPK抑制剂可能具有逆转糖皮质激素不敏感并重建糖皮质激素对重度哮喘患者有益作用的潜力。
