Aspergillus fumigatus germ tube growth and not conidia ingestion induces expression of inflammatory mediator genes in the human lung epithelial cell line A549
Aspergillus fumigatus germ tube growth and not conidia ingestion induces expression of inflammatory mediator genes in the human lung epithelial cell line A549
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DOI：
10.1099/jmm.0.005488-0
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发表时间：
2009-02-01
影响因子：
3
通讯作者：
Bretagne, Stephane
中科院分区：
文献类型：
--
作者：
Bellanger, Anne-Pauline;Millon, Laurence;Bretagne, Stephane
分生孢子的吸入是侵袭性肺曲霉病（IPA）的主要病因，呼吸道上皮是IPA的第一道防线。为了探讨烟曲霉（Aspergillus fumigatus）引起炎症反应的触发因素，本研究分析了A549细胞在活分生孢子和灭活分生孢子攻击后三种炎症基因的差异表达。类固醇的影响，发展IPA的主要危险因素之一，也进行了调查。使用实时PCR对编码白细胞介素（IL）-8、肿瘤坏死因子（TNF）-α和粒细胞-单核细胞集落刺激因子（GM-CSF）的炎症介质基因的mRNA进行定量。研究了该菌分生孢子的取食率。烟曲霉和产黄青霉使用荧光增亮剂。两个物种获得了类似的结果，摄食率范围为35%至40%。将A549细胞暴露于活A.烟曲霉分生孢子仅诱导三种基因的mRNA水平增加四到五倍，从最初接触后8小时开始。活A.烟曲霉分生孢子和地塞米松（10（-7）M）处理防止TNF-α、IL-8和GM-CSF的过表达。真菌的生长，而不是分生孢子的摄入，似乎是上皮细胞产生炎症介质的主要刺激，这种生产是抑制类固醇治疗。这些结果强调了上皮细胞在对IPA的先天反应中所起的作用。
Inhalation of conidia is the main cause of invasive pulmonary aspergillosis (IPA) and the respiratory epithelium is the first line of defence. To explore the triggering factor for the inflammatory response to Aspergillus fumigatus, the species mainly responsible for IPA, this study analysed the differential expression of three inflammatory genes in A549 cells after challenge with live and killed conidia. The influence of steroids, one of the main risk factors for developing IPA, was also investigated. Quantification of mRNAs of the inflammatory mediator genes encoding interleukin (IL)-8, tumour necrosis factor (TNF)-alpha and granulocyte-monocyte colony-stimulating factor (GM-CSF) was carried out using real-time PCR. Ingestion rates were studied for the conidia of A. fumigatus and Penicillium chrysogenum using a fluorescence brightener. Similar results were obtained for both species, with ingestion rates ranging from 35 to 40 %. Exposure of A549 cells to live A. fumigatus conidia only induced a four- to fivefold increase in the mRNA levels of the three genes, starting 8 h after the initial contact. Both inactivation of live A. fumigatus conidia and treatment by dexamethasone (10(-7) M) prevented the overexpression of TNF-alpha, IL-8 and GM-CSF. Fungal growth, rather than conidia ingestion, appears to be the main stimulus for the production of inflammatory mediators by epithelial cells, and this production is inhibited by steroid therapy. These results underline the role that the epithelium plays in the innate response against IPA.