Chen Lingxiu, Ran Danhua, Xie Wenyue, Xu Qing, Zhou Xiangdong
Department of Respiratory Medicine, The Second Affiliated Hospital of Chongqing Medical University, No. 74, Linjiang Road, Yuzhong District, Chongqing 400010, China.
Int Immunopharmacol. 2016 Oct;39:48-56. doi: 10.1016/j.intimp.2016.07.007. Epub 2016 Jul 13.
Mucus overproduction is an important feature in patients with chronic inflammatory airway diseases and cold air stimulation has been shown to be associated with the severity of these diseases. However, the regulatory mechanisms that mediate excessive mucin production under cold stress remain elusive. Recently, the cold-inducible RNA-binding protein (CIRP) has been shown to be markedly induced after exposure to cold air. In this study, we sought to explore the expression of CIRP within bronchial biopsy specimens, the effect on mucin5AC (MUC5AC) production in chronic inflammatory airway diseases and the potential signaling pathways involved in cold air stimulation process. We found that CIRP protein expression was significantly increased in patients with COPD and in mice treated with cold air. Moreover, cold air stimulation induced MUC5AC expression in wild-type mice but not in CIRP(-/-) mice. In vitro, cold air stress significantly elevated the transcriptional and protein expression levels of MUC5AC in human bronchial epithelial cells. CIRP, toll-like receptor 4 (TLR4) and phosphorylated NF-κB p65 (p-p65) increased significantly in response to cold stress and CIRP siRNA, TLR4 - neutralizing Ab and a specific inhibitor of NF-κB could attenuated cold stress inducible MUC5AC expression. In addition, CIRP siRNA could hindered the expression levels of TLR4 and p-p65 both induced by cold stress. Taken together, these results suggest that airway epithelial cells constitutively express CIRP in vitro and in vivo. CIRP is responsible for cold-inducible MUC5AC expression by activating TLR4/NF-κB signaling pathway.
黏液过度分泌是慢性炎症性气道疾病患者的一个重要特征，并且已表明冷空气刺激与这些疾病的严重程度相关。然而，在冷应激下介导黏蛋白过度产生的调节机制仍不清楚。最近，已表明冷诱导RNA结合蛋白（CIRP）在暴露于冷空气后会显著诱导表达。在本研究中，我们试图探究支气管活检标本中CIRP的表达、其对慢性炎症性气道疾病中黏蛋白5AC（MUC5AC）产生的影响以及冷空气刺激过程中涉及的潜在信号通路。我们发现慢性阻塞性肺疾病（COPD）患者以及接受冷空气处理的小鼠中CIRP蛋白表达显著增加。此外，冷空气刺激在野生型小鼠中诱导MUC5AC表达，但在CIRP基因敲除（CIRP(-/-)）小鼠中未诱导。在体外，冷空气应激显著提高人支气管上皮细胞中MUC5AC的转录和蛋白表达水平。CIRP、Toll样受体4（TLR4）和磷酸化核因子κB p65（p-p65）在冷应激反应中显著增加，并且CIRP小干扰RNA（siRNA）、TLR4中和抗体以及NF-κB的特异性抑制剂可减弱冷应激诱导的MUC5AC表达。此外，CIRP siRNA可阻碍冷应激诱导的TLR4和p-p65的表达水平。综上所述，这些结果表明气道上皮细胞在体外和体内均组成性表达CIRP。CIRP通过激活TLR4/NF-κB信号通路负责冷诱导的MUC5AC表达。
