Issa Razao, Xie Shaoping, Khorasani Nadia, Sukkar Maria, Adcock Ian M, Lee Kang-Yun, Chung Kian Fan
Experimental Medicine, Airway Studies Section, National Heart and Lung Institute, Imperial College, London, United Kingdom.
J Immunol. 2007 Jun 1;178(11):7366-75. doi: 10.4049/jimmunol.178.11.7366.
Expression of the inflammatory chemokine, growth-related oncogene protein-alpha (GRO-alpha), from airway smooth muscle cells (ASMC) is regulated by pathways involving NF-kappaB and MAPK activation. We determined the effects of dexamethasone on GRO-alpha induced by IL-1beta or TNF-alpha with respect to the role of MAPK pathways and of MAPK phosphatase-1 (MKP-1). Human ASMC were studied in primary culture at confluence. Dexamethasone (10(-8)-10(-5) M) partially inhibited GRO-alpha expression and release induced by IL-1beta and TNF-alpha; this was associated with an inhibition of JNK, but not of p38 or ERK phosphorylation. Together with IL-1beta or TNF-alpha, dexamethasone rapidly induced mRNA and protein expression of MKP-1, which dephosphorylates MAPKs. Using MKP-1 small interfering RNA (siRNA) to block the expression of IL-1beta- and dexamethasone-induced MKP-1 by 50%, JNK phosphorylation was doubled. The inhibitory effect of dexamethasone on GRO-alpha release was partially reversed in ASMC treated with MKP-1 siRNA compared with those treated with scrambled siRNA. In contrast, overexpression of MKP-1 led to a reduction in IL-1beta-induced release of GRO-alpha, but the inhibitory effects of dexamethasone were preserved. Nuclear translocation of the glucocorticoid receptor was increased in ASMC exposed to dexamethasone and IL-1beta. Using chromatin immunoprecipitation assay, glucocorticoid receptor binding to the MKP-1 promoter was increased by IL-1beta and dexamethasone compared with either alone. Glucocorticoids and IL-1beta or TNF-alpha modulate GRO-alpha release partly through the inhibition of JNK pathway, resulting from an up-regulation of MKP-1 expression.
气道平滑肌细胞（ASMC）中炎性趋化因子生长相关癌基因蛋白-α（GRO-α）的表达受涉及核因子-κB（NF-κB）和丝裂原活化蛋白激酶（MAPK）激活的信号通路调控。我们就MAPK信号通路和丝裂原活化蛋白激酶磷酸酶-1（MKP-1）的作用，确定了地塞米松对白细胞介素-1β（IL-1β）或肿瘤坏死因子-α（TNF-α）诱导的GRO-α的影响。对人ASMC进行原代汇合培养研究。地塞米松（10⁻⁸ - 10⁻⁵ M）部分抑制IL-1β和TNF-α诱导的GRO-α表达和释放；这与JNK磷酸化的抑制相关，但与p38或细胞外信号调节激酶（ERK）磷酸化无关。与IL-1β或TNF-α一起，地塞米松迅速诱导MKP-1的mRNA和蛋白表达，MKP-1可使MAPKs去磷酸化。使用MKP-1小干扰RNA（siRNA）将IL-1β和地塞米松诱导的MKP-1表达阻断50%，JNK磷酸化增加一倍。与用乱序siRNA处理的ASMC相比，在用MKP-1 siRNA处理的ASMC中，地塞米松对GRO-α释放的抑制作用部分逆转。相反，MKP-1的过表达导致IL-1β诱导的GRO-α释放减少，但地塞米松的抑制作用仍然存在。在地塞米松和IL-1β作用下，ASMC中糖皮质激素受体的核转位增加。使用染色质免疫沉淀分析，与单独处理相比，IL-1β和地塞米松共同作用可增加糖皮质激素受体与MKP-1启动子的结合。糖皮质激素和IL-1β或TNF-α部分通过抑制JNK信号通路来调节GRO-α释放，这是由MKP-1表达上调所致。
