Bansal Tarun, Kim Dae N, Slininger Tim, Wood Thomas K, Jayaraman Arul
Department of Chemical Engineering, Texas A&M University, College Station, TX, USA.
FEMS Immunol Med Microbiol. 2012 Dec;66(3):399-410. doi: 10.1111/1574-695X.12004.
To better understand the role of host cell-derived molecules on enterohemorrhagic Escherichia coli (EHEC) infection, we studied EHEC virulence gene expression when exposed to cell-free spent (conditioned) medium (CM) from HCT-8 intestinal epithelial cells. Exposure to HCT-8 CM for 1 h and 3 h increased the expression of 32 of 41 EHEC locus of enterocyte effacement (LEE) virulence genes compared with fresh medium (FM). Expression of the Shiga toxin 1 (stx1B) gene was up-regulated at 1 h of exposure. Seventeen genes encoded by prophage 933W, including those for Stx2, were also up-regulated at both time-points. The increase in 933W prophage expression was mirrored by a 2.7-fold increase in phage titers. Consistent with the increase in virulence gene expression, we observed a fivefold increase in EHEC attachment to epithelial cells when exposed to CM. The increase in EHEC attachment was abolished when CM was heated to 95 °C or treated with proteinase K to degrade the proteins. The host cell-derived molecule(s) were larger than 3 kDa, which suggests that the molecule(s) that increase EHEC virulence and attachment are protein-based.
为了更好地理解宿主细胞衍生分子在肠出血性大肠杆菌（EHEC）感染中的作用，我们研究了EHEC暴露于HCT-8肠上皮细胞的无细胞培养上清（条件）培养基（CM）时其毒力基因的表达情况。与新鲜培养基（FM）相比，暴露于HCT-8 CM 1小时和3小时后，41个肠上皮细胞损伤位点（LEE）毒力基因中的32个基因的表达增加。志贺毒素1（stx1B）基因在暴露1小时时上调。由原噬菌体933W编码的17个基因，包括那些编码Stx2的基因，在两个时间点均上调。噬菌体滴度增加2.7倍反映了933W原噬菌体表达的增加。与毒力基因表达增加一致，我们观察到暴露于CM时EHEC对上皮细胞的附着增加了五倍。当CM加热到95°C或用蛋白酶K处理以降解蛋白质时，EHEC附着的增加被消除。宿主细胞衍生分子大于3 kDa，这表明增加EHEC毒力和附着的分子是基于蛋白质的。
