A Francisella mutant in lipid A carbohydrate modification elicits protective immunity.
A Francisella mutant in lipid A carbohydrate modification elicits protective immunity.
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DOI：
10.1371/journal.ppat.0040024
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发表时间：
2008-02-08
期刊：
影响因子：
6.7
通讯作者：
Ernst, Robert K.
中科院分区：
文献类型：
--
作者：
Kanistanon, Duangjit;Hajjar, Adeline M.;Pelletier, Mark R.;Gallagher, Larry A.;Kalhorn, Thomas;Shaffer, Scott A.;Goodlett, David R.;Rohmer, Laurence;Brittnacher, Mitchell J.;Skerrett, Shawn J.;Ernst, Robert K.
土拉热弗朗西丝菌是一种革兰氏阴性杆菌，是引起人类土拉菌病的病原菌。Ft被疾病控制和预防中心指定为A类选择剂。Ft的人类临床分离株产生与小鼠病原体Ft杀鼠亚种（Fn）相似结构的脂质A。我们确定了Fn脂质A碳水化合物修饰所需的三种酶，特别是甘露糖（flmF 1），半乳糖胺（flmF 2）或两种碳水化合物（flmK）的存在。缺乏半乳糖胺（flmF 2）或半乳糖胺/甘露糖（flmK）除了他们的脂质A的突变体在小鼠中减弱肺部和皮下感染途径。此外，突变体（flmF 2和flmK）的雾化提供了针对野生型（WT）Fn攻击的保护，而仅皮下施用flmK突变体提供了针对WT Fn攻击的保护。此外，与WT Fn感染相比，flmK突变体感染肺泡巨噬细胞系诱导更高水平的肿瘤坏死因子-α（TNF-α）和巨噬细胞抑制蛋白-2（MIP-2）。来自Toll样受体4（TLR 4）和TLR 2/4敲除小鼠的感染flmK突变体的骨髓衍生的巨噬细胞（BMMs）也产生比感染WT Fn的BMMs显著更高量的白细胞介素-6（IL-6）和MIP-2。然而，在感染两种菌株的MyD 88 −/−小鼠的BMMPBMC中均检测不到IL-6和MIP-2的产生。MyD 88 −/−小鼠也易受flmK突变体感染。我们假设flmK突变体激活促炎细胞因子/趋化因子产生和MyD 88信号通路介导的先天免疫应答的能力可能是其衰减的原因，导致该突变体诱导保护性免疫。细菌病原体修饰外膜组分，例如脂质A或内毒素（脂多糖的脂质锚），以增强定殖、扩散到不同组织和/或避免宿主的免疫防御的能力。脂多糖还在维持膜完整性方面起重要作用，并且是革兰氏阴性细菌感染的宿主先天免疫识别的关键因素。土拉热弗朗西丝氏菌是人类疾病土拉菌病的病原体，被分类为A类选择性病原体。新杀弗朗西斯菌（Francisella novicida，Fn）是F.土拉热。Francisella spp.脂质A是独特的，因为它被各种碳水化合物修饰，这些碳水化合物在毒力和改变的内毒性中起作用。在我们的研究中，我们确定并定义了参与基础Fn脂质A结构的碳水化合物修饰的三个基因的作用。我们表明，Fn脂质A分子缺乏特异性修饰导致细菌减毒和激活针对致死性野生型感染的保护性免疫应答。因此，弗朗西斯菌脂质A结构的改变可能是弗朗西斯菌属常见的致病策略，特定的脂质A突变株可能是未来疫苗研究的候选者。
Francisella tularensis (Ft) is a highly infectious Gram-negative bacterium and the causative agent of the human disease tularemia. Ft is designated a class A select agent by the Centers for Disease Control and Prevention. Human clinical isolates of Ft produce lipid A of similar structure to Ft subspecies novicida (Fn), a pathogen of mice. We identified three enzymes required for Fn lipid A carbohydrate modifications, specifically the presence of mannose (flmF1), galactosamine (flmF2), or both carbohydrates (flmK). Mutants lacking either galactosamine (flmF2) or galactosamine/mannose (flmK) addition to their lipid A were attenuated in mice by both pulmonary and subcutaneous routes of infection. In addition, aerosolization of the mutants (flmF2 and flmK) provided protection against challenge with wild-type (WT) Fn, whereas subcutaneous administration of only the flmK mutant provided protection from challenge with WT Fn. Furthermore, infection of an alveolar macrophage cell line by the flmK mutant induced higher levels of tumor necrosis factor-α (TNF-α) and macrophage inhibitory protein-2 (MIP-2) when compared to infection with WT Fn. Bone marrow–derived macrophages (BMMø) from Toll-like receptor 4 (TLR4) and TLR2/4 knockout mice infected with the flmK mutant also produced significantly higher amounts of interleukin-6 (IL-6) and MIP-2 than BMMø infected with WT Fn. However, production of IL-6 and MIP-2 was undetectable in BMMø from MyD88−/− mice infected with either strain. MyD88−/− mice were also susceptible to flmK mutant infection. We hypothesize that the ability of the flmK mutant to activate pro-inflammatory cytokine/chemokine production and innate immune responses mediated by the MyD88 signaling pathway may be responsible for its attenuation, leading to the induction of protective immunity by this mutant. Bacterial pathogens modify outer membrane components, such as lipid A or endotoxin, the lipid anchor of lipopolysaccharide, to enhance the ability to colonize, spread to different tissues, and/or avoid the host's immune defenses. Lipopolysaccharide also plays an essential role in maintaining membrane integrity and is a key factor in host innate immune recognition of Gram-negative bacterial infections. Francisella tularensis is the causative agent of the human disease tularemia and is classified as a category A select agent. Francisella novicida (Fn) is the murine counterpart of F. tularensis. The structure of Francisella spp. lipid A is unique in that it is modified by various carbohydrates that play a role in virulence and altered endotoxicity. In our study, we identified and defined the role of three genes involved in the carbohydrate modification of the base Fn lipid A structure. We showed that the lack of specific modification(s) of the Fn lipid A molecule lead to bacterial attenuation and activation of a protective immune response against a lethal wild-type infection. Therefore, alteration of Francisella lipid A structure may represent a pathogenesis strategy common to the Francisella species, and specific lipid A mutant strains may be candidates for inclusion in future vaccine studies.
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影响因子：
4.4
作者：
Cole, Leah E.;Elkins, Karen L.;Vogel, Stefanie N.
通讯作者：
Vogel, Stefanie N.
DOI：
10.1111/j.1432-1033.1983.tb07832.x
发表时间：
1983-01-01
期刊：
EUROPEAN JOURNAL OF BIOCHEMISTRY
影响因子：
--
作者：
HOLST, O;BOROWIAK, D;MAYER, H
通讯作者：
MAYER, H
DOI：
10.1016/j.jasms.2007.03.008
发表时间：
2007-06-01
影响因子：
3.2
作者：
Shaffer, Scott A.;Harvey, Megan D.;Ernst, Robert K.
通讯作者：
Ernst, Robert K.
影响因子：
3.2
作者：
Svensson, K;Larsson, P;Johansson, A
通讯作者：
Johansson, A
影响因子：
3.8
作者：
Telepnev, M;Golovliov, I;Sjöstedt, A
通讯作者：
Sjöstedt, A