Institut für Laboratoriums- und Transfusionsmedizin, Herz- und Diabeteszentrum Nordrhein-Westfalen, Bad Oeynhausen, Germany.
BMC Microbiol. 2010 Mar 16;10:78. doi: 10.1186/1471-2180-10-78.
Streptococcus gallolyticus subsp. gallolyticus is an important causative agent of infective endocarditis (IE) but the knowledge on virulence factors is limited and the pathogenesis of the infection is poorly understood. In the present study, we established an experimental in vitro IE cell culture model using EA.hy926 and HUVEC cells to investigate the adhesion and invasion characteristics of 23 Streptococcus gallolyticus subsp. gallolyticus strains from different origins (human IE-derived isolates, other human clinical isolates, animal isolates). Adhesion to eight components of the extracellular matrix (ECM) and the ability to form biofilms in vitro was examined in order to reveal features of S. gallolyticus subsp. gallolyticus endothelial infection. In addition, the strains were analyzed for the presence of the three virulence factors gtf, pilB, and fimB by PCR.
The adherence to and invasion characteristics of the examined S. gallolyticus subsp. gallolyticus strains to the endothelial cell line EA.hy926 differ significantly among themselves. In contrast, the usage of three different in vitro models (EA.hy926 cells, primary endothelial cells (HUVECs), mechanical stretched cells) revealed no differences regarding the adherence to and invasion characteristics of different strains. Adherence to the ECM proteins collagen I, II and IV revealed the highest values, followed by fibrinogen, tenascin and laminin. Moreover, a strong correlation was observed in binding to these proteins by the analyzed strains. All strains show the capability to adhere to polystyrole surfaces and form biofilms. We further confirmed the presence of the genes of two known virulence factors (fimB: all strains, gtf: 19 of 23 strains) and demonstrated the presence of the gene of one new putative virulence factor (pilB: 9 of 23 strains) by PCR.
Our study provides the first description of S. gallolyticus subsp. gallolyticus adhesion and invasion of human endothelial cells, revealing important initial information of strain variability, behaviour and characteristics of this as yet barely analyzed pathogen.
牛链球菌亚种是感染性心内膜炎（IE）的重要病原体，但对其毒力因子的了解有限，感染的发病机制也知之甚少。本研究采用 EA.hy926 和 HUVEC 细胞建立了体外 IE 细胞培养模型，以研究来自不同来源（人 IE 分离株、其他人类临床分离株、动物分离株）的 23 株牛链球菌亚种的粘附和侵袭特性。为了揭示牛链球菌亚种内皮感染的特征，我们检测了其对细胞外基质（ECM）的 8 种成分的粘附能力和体外生物膜形成能力。此外，通过 PCR 分析了这些菌株是否存在 gtf、pilB 和 fimB 三种毒力因子。
被检牛链球菌亚种对 EA.hy926 内皮细胞系的粘附和侵袭特性差异显著。相比之下，在三种不同的体外模型（EA.hy926 细胞、原代内皮细胞（HUVEC）、机械拉伸细胞）中，不同菌株的粘附和侵袭特性没有差异。对 ECM 蛋白胶原 I、II 和 IV 的粘附率最高，其次是纤维蛋白原、腱生蛋白和层粘连蛋白。此外，分析菌株之间对这些蛋白的结合具有很强的相关性。所有菌株均具有粘附聚苯乙烯表面和形成生物膜的能力。我们进一步通过 PCR 证实了两种已知毒力因子（fimB：所有菌株，gtf：23 株中的 19 株）基因的存在，并证明了一个新的假定毒力因子（pilB：23 株中的 9 株）基因的存在。
本研究首次描述了牛链球菌亚种对人内皮细胞的粘附和侵袭，为该病原体的菌株变异性、行为和特征提供了重要的初步信息，该病原体目前尚未得到充分分析。
