TNFα是一种作用很强的细胞因子,除对肿瘤细胞有特异的杀伤作用外,还有抗病毒、激活T细胞、促进细胞因子分泌和诱发炎症反应等重要生物功能。本组实验观察到,TNFα刺激16HBE引起ICAM1mRNA表达增高,与以往的报道类似〔7〕,TNFα可诱导一系列与炎症有关的细胞因子〔如IL1、IL6、IL8、粒细胞巨噬细胞集落刺激因子(GMCSF)〕、黏附分子〔如ICAM1、血管细胞间黏附因子1(VCAM1)〕的生成,通过诱导这些因子的产生和释放,造成机体炎症损伤,同时,通过再激活炎症效应细胞,释放更多的炎性因子,使炎症信号进一步放大和加强。本实验还显示,不同浓度EM作用于16HBE 24 h或48 h后,再用TNFα刺激16 h,与仅用TNFα刺激组比较,16HBE ICAM1mRNA表达均降低,提示有浓度和时间依赖性。本实验从分子水平上说明EM能抑制ICAM1mRNA表达,且与其作用浓度和时间相关,这一机制可能是EM抗炎作用机制之一。在国外,Suzuki等〔8〕研究发现,EM抑制病毒感染人气管上皮细胞导致的ICAM1分泌从而调节气道炎症。Sanz等〔9〕报告在老鼠体内实验中,EM抑制白细胞在肺内的聚集,其机制是通过下调ICAM1mRNA和VCAM1 mRNA表达。Li等〔10,11〕研究结果显示大环内酯类抗生素能抑制博来霉素诱导大鼠的急性肺损伤和肺纤维,其作用机制主要是通过抑制ICAM1mRNA和VCAM1mRNA表达从而抑制白细胞特别是中性粒细胞向气道内迁移。有临床实验证明,长期小剂量EM治疗COPD患者,可显著减少患者感冒发生率,对阻止COPD患者病情恶化有良好的效果,这种效果是EM的抗炎而非抗菌机制所致,可能与EM能抑制16HBE表达和释放IL6、IL8和ICAM1有关〔12〕。
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