Wilson Sylvia M, Shen Pamela, Rider Christopher F, Traves Suzanne L, Proud David, Newton Robert, Giembycz Mark A
Department of Physiology and Pharmacology, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada.
J Immunol. 2009 Nov 15;183(10):6788-99. doi: 10.4049/jimmunol.0902738. Epub 2009 Oct 30.
Prostacyclin receptor (IP-receptor) agonists display anti-inflammatory and antiviral activity in cell-based assays and in preclinical models of asthma and chronic obstructive pulmonary disease. In this study, we have extended these observations by demonstrating that IP-receptor activation also can enhance the ability of glucocorticoids to induce genes with anti-inflammatory activity. BEAS-2B bronchial epithelial cells stably transfected with a glucocorticoid response element (GRE) luciferase reporter were activated in a concentration-dependent manner by the glucocorticoid dexamethasone. An IP-receptor agonist, taprostene, increased cAMP in these cells and augmented luciferase expression at all concentrations of dexamethasone examined. Analysis of the concentration-response relationship that described this effect showed that taprostene increased the magnitude of transcription without affecting the potency of dexamethasone and was, thus, steroid-sparing in this simple system. RO3244794, an IP-receptor antagonist, and oligonucleotides that selectively silenced the IP-receptor gene, PTGIR, abolished these effects of taprostene. Infection of BEAS-2B GRE reporter cells with an adenovirus vector encoding a highly selective inhibitor of cAMP-dependent protein kinase (PKA) also prevented taprostene from enhancing GRE-dependent transcription. In BEAS-2B cells and primary cultures of human airway epithelial cells, taprostene and dexamethasone interacted either additively or cooperatively in the expression of three glucocorticoid-inducible genes (GILZ, MKP-1, and p57(kip2)) that have anti-inflammatory potential. Collectively, these data show that IP-receptor agonists can augment the ability of glucocorticoids to induce anti-inflammatory genes in human airway epithelial cells by activating a cAMP/PKA-dependent mechanism. This observation may have clinical relevance in the treatment of airway inflammatory diseases that are either refractory or respond suboptimally to glucocorticoids.
前列环素受体（IP受体）激动剂在基于细胞的试验以及哮喘和慢性阻塞性肺疾病的临床前模型中表现出抗炎和抗病毒活性。在本研究中，我们通过证明IP受体激活还可增强糖皮质激素诱导具有抗炎活性基因的能力，扩展了这些观察结果。稳定转染糖皮质激素反应元件（GRE）荧光素酶报告基因的BEAS-2B支气管上皮细胞，被糖皮质激素地塞米松以浓度依赖的方式激活。IP受体激动剂他前列烯，在这些细胞中增加了环磷酸腺苷（cAMP），并在所有检测的地塞米松浓度下增强了荧光素酶表达。对描述这种效应的浓度-反应关系的分析表明，他前列烯增加了转录幅度，而不影响地塞米松的效力，因此，在这个简单系统中具有类固醇节省作用。IP受体拮抗剂RO3244794以及选择性沉默IP受体基因PTGIR的寡核苷酸，消除了他前列烯的这些效应。用编码cAMP依赖性蛋白激酶（PKA）高度选择性抑制剂的腺病毒载体感染BEAS-2B GRE报告细胞，也可阻止他前列烯增强GRE依赖性转录。在BEAS-2B细胞和人气道上皮细胞原代培养物中，他前列烯和地塞米松在三种具有抗炎潜力的糖皮质激素诱导基因（GILZ、MKP-1和p57(kip2)）的表达中表现出相加或协同作用。总体而言，这些数据表明，IP受体激动剂可通过激活cAMP/PKA依赖性机制，增强糖皮质激素在人气道上皮细胞中诱导抗炎基因的能力。这一观察结果可能在治疗对糖皮质激素难治或反应欠佳的气道炎症性疾病中具有临床意义。
