Gene expression in C57BL/6 mouse lungs after exposure to aerosolized NTHi lysate

Pneumonia is a serious problem worldwide. We recently demonstrated that innate defense mechanisms of the lung are highly inducible against pneumococcal pneumonia. To determine the breadth of protection conferred by stimulation of lung mucosal innate immunity, and to identify cells and signaling pathways activated by this treatment, mice were treated with an aerosolized bacterial lysate, then challenged with lethal doses of bacterial and fungal pathogens. Mice were highly protected against a broad array of Gram-positive, Gram-negative, and Class A bioterror bacterial pathogens, and Aspergillus fumigatus. Protection was associated with rapid pathogen killing within the lungs, and this effect was recapitulated in vitro using a respiratory epithelial cell line. Gene expression analysis of lung tissue showed marked activation of NF-kappaB, Type I and II interferon, and antifungal Card9-Bcl10-Malt1 pathways. Cytokines were the most strongly induced genes, but the inflammatory cytokines TNF and IL-6 were not required for protection. Lung-expressed antimicrobial peptides were also highly upregulated. Taken together, stimulated innate resistance (StIR) appears to occur through the activation of multiple host defense signaling pathways in lung epithelial cells, inducing rapid pathogen killing, and conferring broad protection against virulent bacterial and fungal pathogens. Augmentation of innate antimicrobial defenses of the lungs might have therapeutic value for protection of patients with neutropenia or impaired adaptive immunity against opportunistic pneumonia, and for defense of immunocompetent subjects against a bioterror threat or epidemic respiratory infection. Keywords: differential gene expression; time course; innate immunity; pneumonia; immunocompromised host; lung epithelium Gene expression patterns in mouse lung homogenates were analyzed 2h after exposure to aerosolized PBS (Sham treatment), 2h after exposure to aerosolized NTHi lysate or 4h after exposure to aerosolized NTHi lysate. Each group consisted of six mice.

肺炎是全球范围内的严重公共卫生问题。我们近期证实，肺部固有免疫防御机制可被高效诱导，以抵御肺炎链球菌肺炎。为明确肺黏膜固有免疫刺激所介导的保护范围，并鉴定该处理激活的细胞与信号通路，研究人员对小鼠施以雾化细菌裂解物(aerosolized bacterial lysate)处理，随后以致死剂量的细菌及真菌病原体进行攻毒实验。实验小鼠可被高效保护，抵御多种革兰氏阳性菌、革兰氏阴性菌、A类生物恐怖致病菌以及烟曲霉(Aspergillus fumigatus)的感染。该保护效应与肺部内病原体的快速清除密切相关，且这一现象可通过呼吸道上皮细胞系(respiratory epithelial cell line)在体外重现。肺组织的基因表达分析显示，核因子κB(NF-kappaB)、I型与II型干扰素以及抗真菌Card9-Bcl10-Malt1信号通路均被显著激活。细胞因子是诱导表达最为显著的基因类群，但炎性细胞因子肿瘤坏死因子(TNF)与白细胞介素6(IL-6)并非保护效应所必需。肺部表达的抗菌肽同样被显著上调。综上，刺激诱导的固有抵抗力(StIR)似乎通过激活肺上皮细胞内多条宿主防御信号通路实现，可快速清除病原体，并赋予宿主针对强毒力细菌与真菌病原体的广谱保护能力。增强肺部固有抗菌防御能力，或可用于保护中性粒细胞减少症患者、适应性免疫受损患者抵御机会性肺炎，同时也可帮助免疫健全个体抵御生物恐怖威胁或流行性呼吸道感染。关键词：差异基因表达；时间进程；固有免疫；肺炎；免疫受损宿主；肺上皮细胞。研究人员对暴露于雾化磷酸盐缓冲液(PBS，假处理)2小时、雾化非可分型流感嗜血杆菌(NTHi)裂解物2小时以及雾化NTHi裂解物4小时后的小鼠肺组织匀浆的基因表达模式进行了分析。每组包含6只小鼠。