Nat Med：室内尘土中的细菌鞭毛蛋白能够加重哮喘

2012年10月17日 讯 /生物谷BIOON/ --根据一项美国国家卫生研究院和杜克大学开展的一项研究，常见的室内尘土中存在的一种细菌蛋白可能会加重对室内过敏原产生的过敏反应。这项发现是第一次记录室内尘土中存在鞭毛蛋白(flagellin)，并且支持过敏性哮喘与环境存在关联。相关研究结果于10月14日在线发表在Nature Medicine期刊上。

论文通讯作者Donald Cook博士说，“大多数人所患的哮喘是过敏性哮喘，主要是由于对吸入的物质产生的过敏反应产生的。”他的研究团开展这项研究以便鉴定出扩大这种过敏反应的环境因子。“尽管鞭毛蛋白不是一种过敏原，但是它能够提高对真正的过敏原产生的过敏反应。”

在吸入室内尘土后，能够对鞭毛蛋白作出反应的小鼠表现出过敏性哮喘的常见性症状，包括更多的粘膜产生、气道阻塞和气道炎症。然而，缺乏检测鞭毛蛋白存在的基因的小鼠表现出这些低水平的症状。

Cook说，“还需开展更多的研究来证实我们的结论，但是清理房间总体上能够降低室内尘土的数量，特别是降低带有鞭毛的细菌的数量，从而会降低过敏性哮喘的发病率。”

除了小鼠研究外，研究人员也证实相对于非哮喘性人们，患有哮喘的人们在血液中含有较高水平的对抗鞭毛蛋白的抗体，从而提供更多的证据证实环境因子与人们患上的过敏性哮喘存在关联。

与哮喘相关的拓展阅读：

• JCI：新药物可限制粘液过多生成以治疗哮喘及COPD  
• JAMA：研究支持舌下免疫疗法治疗过敏性鼻炎和哮喘
• Thorax：快餐或增加儿童哮喘风险
• JAMA：舌下免疫疗法能用于过敏性鼻炎和哮喘的治疗
• Thorax：快餐或增加儿童哮喘风险 更多信息请点击：有关哮喘更多资讯

The Toll-like receptor 5 ligand flagellin promotes asthma by priming allergic responses to indoor allergens

Allergic asthma is a complex disease characterized by eosinophilic pulmonary inflammation, mucus production and reversible airway obstruction1. Exposure to indoor allergens is a risk factor for asthma, but this disease is also associated with high household levels of total and particularly Gram-negative bacteria2. The ability of bacterial products to act as adjuvants3 suggests they might promote asthma by priming allergic sensitization to inhaled allergens. In support of this idea, house dust extracts (HDEs) can activate antigen-presenting dendritic cells (DCs) in vitro and promote allergic sensitization to inhaled innocuous proteins in vivo4. It is unknown which microbial products provide most of the adjuvant activity in HDEs. A screen for adjuvant activity of microbial products revealed that the bacterial protein flagellin (FLA) stimulated strong allergic airway responses to an innocuous inhaled protein, ovalbumin (OVA). Moreover, Toll-like receptor 5 (TLR5), the mammalian receptor for FLA5, 6, was required for priming strong allergic responses to natural indoor allergens present in HDEs. In addition, individuals with asthma have higher serum levels of FLA-specific antibodies as compared to nonasthmatic individuals. Together, these findings suggest that household FLA promotes the development of allergic asthma by TLR5-dependent priming of allergic responses to indoor allergens.