O'Brien Louise M, Walsh Evelyn J, Massey Ruth C, Peacock Sharon J, Foster Timothy J
Moyne Institute of Preventive Medicine, Department of Microbiology, Trinity College Dublin, Dublin 2, Ireland.
Cell Microbiol. 2002 Nov;4(11):759-70. doi: 10.1046/j.1462-5822.2002.00231.x.
Staphylococcus aureus is an important cause of sepsis in both community and hospital settings, a major risk factor for which is nasal carriage of the bacterium. Eradication of carriage by topical antibiotics reduces sepsis rates in high-risk individuals, an important strategy for the reduction of nosocomial infection in targeted patient populations. Understanding the mechanisms by which S. aureus adheres to nasal epithelial cells in vivo may lead to alternative methods of decolonization that do not rely on sustained antimicrobial susceptibility. Here, we demonstrate for the first time that the S. aureus surface-expressed protein, clumping factor B (ClfB), promotes adherence to immobilized epidermal cytokeratins in vitro. By expressing a range of S. aureus adhesins on the surface of the heterologous host Lactococcus lactis, we demonstrated that adherence to epidermal cytokeratins was conferred by ClfB. Adherence of wild-type S. aureus was inhibited by recombinant ClfB protein or anti-ClfB antibodies, and S. aureus mutants defective in ClfB adhered poorly to epidermal cytokeratins. Expression of ClfB promoted adherence of L. lactis to human desquamated nasal epithelial cells, and a mutant of S. aureus defective in ClfB had reduced adherence compared with wild type. ClfB also promoted adherence of L. lactis cells to a human keratinocyte cell line. Cytokeratin 10 molecules were shown by flow cytometry to be exposed on the surface of both desquamated nasal epithelial cells and keratinocytes. Cytokeratin 10 was also detected on the surface of desquamated human nasal cells using immunofluorescence, and recombinant ClfB protein was shown to bind to cytokeratin K10 extracted from these cells. We also showed that ClfB is transcribed by S. aureus in the human nares. We propose that ClfB is a major determinant in S. aureus nasal colonization.
金黄色葡萄球菌是社区和医院环境中脓毒症的重要病因，其主要危险因素是该细菌的鼻腔携带。通过局部使用抗生素消除携带可降低高危个体的脓毒症发生率，这是降低目标患者群体医院感染的重要策略。了解金黄色葡萄球菌在体内粘附于鼻上皮细胞的机制可能会带来不依赖于持续抗菌敏感性的非定植替代方法。在此，我们首次证明金黄色葡萄球菌表面表达的蛋白聚集因子B（ClfB）在体外促进对固定化表皮细胞角蛋白的粘附。通过在异源宿主乳酸乳球菌表面表达一系列金黄色葡萄球菌粘附素，我们证明对表皮细胞角蛋白的粘附是由ClfB赋予的。重组ClfB蛋白或抗ClfB抗体可抑制野生型金黄色葡萄球菌的粘附，且ClfB缺陷的金黄色葡萄球菌突变体对表皮细胞角蛋白的粘附较差。ClfB的表达促进了乳酸乳球菌对人脱落鼻上皮细胞的粘附，与野生型相比，ClfB缺陷的金黄色葡萄球菌突变体的粘附减少。ClfB还促进了乳酸乳球菌细胞对人角质形成细胞系的粘附。通过流式细胞术显示角蛋白10分子暴露于脱落的鼻上皮细胞和角质形成细胞表面。使用免疫荧光在脱落的人鼻细胞表面也检测到角蛋白10，并且重组ClfB蛋白显示与从这些细胞中提取的角蛋白K10结合。我们还表明ClfB在人鼻腔中由金黄色葡萄球菌转录。我们提出ClfB是金黄色葡萄球菌鼻腔定植的主要决定因素。
