Department of Anatomy II, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany.
PLoS One. 2013;8(1):e53705. doi: 10.1371/journal.pone.0053705. Epub 2013 Jan 22.
Surfactant proteins (SP), originally known from human lung surfactant, are essential to proper respiratory function in that they lower the surface tension of the alveoli. They are also important components of the innate immune system. The functional significance of these proteins is currently reflected by a very large and growing number of publications. The objective goal of this study was to elucidate whether Staphylococcus aureus and Pseudomonas aeruginosa is able to express surfactant proteins. 10 different strains of S. aureus and P. aeruginosa were analyzed by means of RT-PCR, Western blot analysis, ELISA, immunofluorescence microscopy and immunoelectron microscopy. The unexpected and surprising finding revealed in this study is that different strains of S. aureus and P. aeruginosa express and secrete proteins that react with currently commercially available antibodies to known human surfactant proteins. Our results strongly suggest that the bacteria are either able to express 'human-like' surfactant proteins on their own or that commercially available primers and antibodies to human surfactant proteins detect identical bacterial proteins and genes. The results may reflect the existence of a new group of bacterial surfactant proteins and DNA currently lacking in the relevant sequence and structure databases. At any rate, our knowledge of human surfactant proteins obtained from immunological and molecular biological studies may have been falsified by the presence of bacterial proteins and DNA and therefore requires critical reassessment.
表面活性蛋白（SP）最初在人肺表面活性物质中被发现，对呼吸功能至关重要，因为它们降低了肺泡的表面张力。它们也是先天免疫系统的重要组成部分。这些蛋白质的功能意义目前反映在大量不断增长的出版物中。本研究的目的是阐明金黄色葡萄球菌和铜绿假单胞菌是否能够表达表面活性蛋白。通过 RT-PCR、Western blot 分析、ELISA、免疫荧光显微镜和免疫电子显微镜分析了 10 株不同的金黄色葡萄球菌和铜绿假单胞菌。这项研究的一个令人惊讶的发现是，不同株的金黄色葡萄球菌和铜绿假单胞菌表达并分泌与目前市售的针对已知人类表面活性蛋白的抗体发生反应的蛋白。我们的结果强烈表明，这些细菌要么能够自行表达“类人”表面活性蛋白，要么市售的针对人类表面活性蛋白的引物和抗体能够检测到相同的细菌蛋白和基因。这些结果可能反映了目前在相关序列和结构数据库中缺乏的一组新的细菌表面活性蛋白和 DNA 的存在。无论如何，我们从免疫学和分子生物学研究中获得的关于人类表面活性蛋白的知识可能已经被细菌蛋白和 DNA 所证实，因此需要进行批判性的重新评估。
