Adcock I M, Lane S J, Brown C R, Lee T H, Barnes P J
Department of Thoracic Medicine, National Heart and Lung Institute, London, United Kingdom.
J Exp Med. 1995 Dec 1;182(6):1951-8. doi: 10.1084/jem.182.6.1951.
Glucocorticosteroids are a very effective treatment for asthma and other chronic inflammatory diseases. However, a small proportion of patients is resistant to the therapeutic effects of glucocorticoids. Pharmacokinetic and ligand binding studies suggest that the molecular abnormality in steroid resistance lies distal to nuclear translocation. We have previously reported that there is a decreased ability of glucocorticoid receptors (GR) to bind to the DNA-binding site in peripheral blood mononuclear cells (PBMC) after dexamethasone treatment. This reduced DNA binding was due to a decrease in the number of receptors available rather than an alteration in affinity for DNA. To study this reduced DNA binding, we examined the ability of the nuclear translocated transcription factors activator protein 1 (AP-1), nuclear factor kappa B (NF-kappa B) and cyclic AMP response element-binding protein (CREB) to bind to their DNA-binding sites and to interact with GR in PBMC from patients with steroid-sensitive and steroid-resistant asthma. There was a significant reduction in the interaction between GR and AP-1 in these steroid-resistant patients, although interaction with other transcription factors activated in inflammation (NF-kappa B and CREB) was unaffected. An increase in the basal levels of AP-1 DNA binding was also detected in the nuclei from steroid-resistant asthmatic patients. There were no differences in the amount of messenger RNA detected for the components of AP-1, c-Fos and c-Jun, nor in the sequences of these messenger RNAs. These results suggest either that the ability of the GR to bind to glucocorticoid response elements and AP-1 is altered in steroid-resistant patients or that increased levels of AP-1 prevent GR DNA binding, and that this may be the molecular basis of resistance to the antiinflammatory effect of steroids in these cells.
糖皮质激素是治疗哮喘和其他慢性炎症性疾病的一种非常有效的药物。然而，一小部分患者对糖皮质激素的治疗效果具有抗性。药代动力学和配体结合研究表明，类固醇抗性的分子异常发生在核转位之后。我们之前报道过，地塞米松治疗后，外周血单核细胞（PBMC）中糖皮质激素受体（GR）与DNA结合位点的结合能力下降。这种DNA结合减少是由于可用受体数量的减少，而非对DNA亲和力的改变。为了研究这种减少的DNA结合，我们检测了核转位转录因子激活蛋白1（AP-1）、核因子κB（NF-κB）和环磷酸腺苷反应元件结合蛋白（CREB）与它们的DNA结合位点结合以及与类固醇敏感和类固醇抗性哮喘患者PBMC中的GR相互作用的能力。在这些类固醇抗性患者中，GR与AP-1之间的相互作用显著降低，尽管与炎症中激活的其他转录因子（NF-κB和CREB）的相互作用未受影响。在类固醇抗性哮喘患者的细胞核中还检测到AP-1 DNA结合的基础水平增加。对于AP-1的组成成分c-Fos和c-Jun检测到的信使RNA量以及这些信使RNA的序列均无差异。这些结果表明，在类固醇抗性患者中，GR与糖皮质激素反应元件和AP-1结合的能力发生了改变，或者AP-1水平的增加阻止了GR与DNA的结合，而这可能是这些细胞中对类固醇抗炎作用产生抗性的分子基础。
