Dawson Charlotte, Dhanda Ashwin, Conway-Campbell Becky, Dimambro Alexandra, Lightman Stafford, Dayan Colin
Department of Clinical Biochemistry, Bristol Royal Infirmary, Bristol, UK.
J Recept Signal Transduct Res. 2012 Feb;32(1):29-35. doi: 10.3109/10799893.2011.641977. Epub 2011 Dec 20.
Resistance to the anti-inflammatory and immunosuppressive effects of steroids is an important clinical problem that complicates the treatment of approximately 30% of patients with conditions for which steroids are normally first-line therapy. Previous studies have shown that steroid-resistant (SR) patients have more severe disease and higher levels of inflammatory cytokine production than steroid-sensitive (SS) patients, but the molecular mechanisms for this remain poorly understood. Peripheral blood mononuclear cells from healthy volunteers were tested for steroid resistance by their in vitro response to the anti-proliferative effects of dexamethasone. The SR cohort had high baseline levels of NFκB DNA binding activity, equivalent to that in phytohemagglutinin (PHA)-stimulated SS cells. In SR cells, dexamethasone exposure, but not PHA, increased binding of the p65 NFκB subunit to the κB promoter element. Glucocorticoid receptor (GR) was not detected at either the κB promoter element or the glucocorticoid response element (GRE), suggesting that it does not translocate to the nucleus in these cells. Conversely, in SS cells, baseline p65 DNA binding activity was low and significantly increased by PHA, but not by dexamethasone. Unlike in SR cells, GR was detected at the κB element and at the GRE. These findings suggest that in SR patients, steroids may be harmful by increasing NFκB activity which would exacerbate disease by increasing transcription of inflammatory cytokines.
对类固醇抗炎和免疫抑制作用产生抵抗是一个重要的临床问题，使约30%通常将类固醇作为一线治疗药物的疾病患者的治疗变得复杂。以往研究表明，与类固醇敏感（SS）患者相比，类固醇抵抗（SR）患者的疾病更严重，炎症细胞因子产生水平更高，但其分子机制仍知之甚少。通过检测健康志愿者外周血单个核细胞对 dexamethasone抗增殖作用的体外反应来测试其对类固醇的抵抗性。SR队列的NFκB DNA结合活性基线水平较高，与植物血凝素（PHA）刺激的SS细胞相当。在SR细胞中，dexamethasone暴露而非PHA增加了p65 NFκB亚基与κB启动子元件的结合。在κB启动子元件或糖皮质激素反应元件（GRE）处均未检测到糖皮质激素受体（GR），这表明它在这些细胞中不会转运至细胞核。相反，在SS细胞中，基线p65 DNA结合活性较低，PHA可使其显著增加，但dexamethasone则不能。与SR细胞不同，在κB元件和GRE处检测到了GR。这些发现表明，在SR患者中，类固醇可能通过增加NFκB活性而有害，这会通过增加炎症细胞因子的转录而加重疾病。
