Novel role for the Streptococcus pneumoniae toxin pneumolysin in the assembly of biofilms.
Novel role for the Streptococcus pneumoniae toxin pneumolysin in the assembly of biofilms.
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DOI：
10.1128/mbio.00655-13
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发表时间：
2013-09-10
期刊：
影响因子：
6.4
通讯作者：
Vidal JE
中科院分区：
文献类型：
--
作者：
Shak JR;Ludewick HP;Howery KE;Sakai F;Yi H;Harvey RM;Paton JC;Klugman KP;Vidal JE
肺炎链球菌是一种重要的传染病和病原体，每年造成近100万5岁以下儿童死亡。肺炎链球菌生物膜的形成在鼻咽定植、肺炎和中耳炎中是重要的。肺炎链球菌溶血素（Ply）是一种对肺炎链球菌的毒力有显著贡献的毒素，并且是作为不依赖于菌型的疫苗靶标的重要候选者。先前已经证明luxS敲除突变体不能形成早期生物膜并且表达比野生型更少的ply mRNA，我们进行了一项研究以调查Ply在生物膜形成中的作用。我们发现，Ply表达在生物膜发展的早期阶段，并定位于细胞聚集体早在4小时接种后。在静态或连续流动条件下培养的聚苯乙烯和人呼吸道上皮细胞上，D39和TIGR4背景中的肺炎链球菌ply敲除突变体在早期时间点产生比野生型菌株显著更少的生物膜生物量。Ply在生物膜形成中的作用似乎与其溶血活性无关，因为肺炎链球菌血清型1菌株（其产生Ply的非溶血性变体）仍然能够形成生物膜。使用免疫金对A549肺细胞上生长的生物膜进行透射电子显微镜检查，结果表明Ply位于肺炎球菌细胞的表面和细胞外生物膜基质中。总之，我们的研究证明了肺炎链球菌溶血素在肺炎链球菌生物膜组装中的新作用，这在携带和疾病期间可能是重要的，因此对于正在开发的肺炎链球菌溶血素靶向疫苗具有重要意义。肺炎链球菌（俗称肺炎球菌）通常在人的鼻咽部携带，并可传播到身体其他部位引起疾病。在鼻咽、中耳和肺中，肺炎球菌形成称为生物膜的多细胞表面相关结构。肺炎链球菌溶血素是几乎所有肺炎链球菌菌株产生的重要毒素，因其对人体组织造成损伤的能力而被广泛研究。在本文中，我们证明了肺炎球菌溶血素在生物膜形成中具有以前未被认识到的作用，表明没有肺炎球菌溶血素的菌株不能在塑料和人类细胞基质上形成相同数量的生物膜。此外，我们发现肺炎球菌溶血素在生物膜形成中的作用与肺炎球菌疾病中导致组织损伤的溶血活性是分开的。肺炎球菌溶血素的这种新作用表明，针对这种蛋白质的肺炎球菌疫苗应研究其对在运输和疾病过程中形成的生物膜的潜在影响。
Streptococcus pneumoniae is an important commensal and pathogen responsible for almost a million deaths annually in children under five. The formation of biofilms by S. pneumoniae is important in nasopharyngeal colonization, pneumonia, and otitis media. Pneumolysin (Ply) is a toxin that contributes significantly to the virulence of S. pneumoniae and is an important candidate as a serotype-independent vaccine target. Having previously demonstrated that a luxS knockout mutant was unable to form early biofilms and expressed less ply mRNA than the wild type, we conducted a study to investigate the role of Ply in biofilm formation. We found that Ply was expressed in early phases of biofilm development and localized to cellular aggregates as early as 4 h postinoculation. S. pneumoniae ply knockout mutants in D39 and TIGR4 backgrounds produced significantly less biofilm biomass than wild-type strains at early time points, both on polystyrene and on human respiratory epithelial cells, cultured under static or continuous-flow conditions. Ply’s role in biofilm formation appears to be independent of its hemolytic activity, as S. pneumoniae serotype 1 strains, which produce a nonhemolytic variant of Ply, were still able to form biofilms. Transmission electron microscopy of biofilms grown on A549 lung cells using immunogold demonstrated that Ply was located both on the surfaces of pneumococcal cells and in the extracellular biofilm matrix. Altogether, our studies demonstrate a novel role for pneumolysin in the assembly of S. pneumoniae biofilms that is likely important during both carriage and disease and therefore significant for pneumolysin-targeting vaccines under development. The bacterium Streptococcus pneumoniae (commonly known as the pneumococcus) is commonly carried in the human nasopharynx and can spread to other body sites to cause disease. In the nasopharynx, middle ear, and lungs, the pneumococcus forms multicellular surface-associated structures called biofilms. Pneumolysin is an important toxin produced by almost all S. pneumoniae strains, extensively studied for its ability to cause damage to human tissue. In this paper, we demonstrate that pneumolysin has a previously unrecognized role in biofilm formation by showing that strains without pneumolysin are unable to form the same amount of biofilm on plastic and human cell substrates. Furthermore, we show that the role of pneumolysin in biofilm formation is separate from the hemolytic activity responsible for tissue damage during pneumococcal diseases. This novel role for pneumolysin suggests that pneumococcal vaccines directed against this protein should be investigated for their potential impact on biofilms formed during carriage and disease.