Giannasca K T, Giannasca P J, Neutra M R
Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA.
Infect Immun. 1996 Jan;64(1):135-45. doi: 10.1128/iai.64.1.135-145.1996.
The mechanism by which Salmonella species adhere to the epithelium of the intestine is not well understood. To identify components on intestinal epithelial cells that may be involved in the initial adherence of Salmonella typhimurium, we correlated patterns of adherence to well-differentiated Caco-2BBe cell monolayers with expression of brush border membrane components and lectin binding sites. This cloned cell line shows heterogeneous expression of sucrase-isomaltase and most lectin receptors. S. typhimurium adhered to a subpopulation of living or formaldehyde-fixed cells with a high multiplicity (up to 150 bacteria per cell). Bacterial binding to selected cells was not correlated with expression of the brush border hydrolases dipeptidyl-peptidase IV and sucrase-isomaltase or with binding of 10 of the 12 lectins tested. However, binding was correlated with the presence of binding sites for peanut agglutinin (PNA) [specific for Gal beta (1-3) GalNAc] and soybean agglutinin (specific for terminal GalNAc). Preincubation of live and fixed Caco-2BBe monolayers with PNA inhibited bacterial binding, while preincubation with soybean agglutinin did not. Electron microscopic analysis demonstrated that the initial adherence of S. typhimurium to Caco-2 cells in vitro involved peripheral components of the glycocalyx on apical microvilli. These results suggest that a Gal beta (1-3)GalNAc epitope recognized by PNA and located in the glycocalyx is involved in the early recognition events between S. typhimurium and Caco-2 cells and that differences in glycosylation patterns among individual epithelial cells may be a determinant in cell-selective adherence of S. typhimurium.
沙门氏菌属附着于肠道上皮的机制尚未完全明确。为了确定肠道上皮细胞上可能参与鼠伤寒沙门氏菌初始附着的成分，我们将对分化良好的Caco - 2BBe细胞单层的附着模式与刷状缘膜成分和凝集素结合位点的表达进行了关联分析。这个克隆细胞系显示蔗糖酶 - 异麦芽糖酶和大多数凝集素受体存在异质性表达。鼠伤寒沙门氏菌以高感染复数（每个细胞多达150个细菌）附着于活的或甲醛固定细胞的一个亚群。细菌与选定细胞的结合与刷状缘水解酶二肽基肽酶IV和蔗糖酶 - 异麦芽糖酶的表达以及所测试的12种凝集素中的10种的结合均无关联。然而，结合与花生凝集素（PNA）[对Galβ(1 - 3)GalNAc具有特异性]和大豆凝集素（对末端GalNAc具有特异性）的结合位点的存在相关。用PNA对活的和固定的Caco - 2BBe单层进行预孵育可抑制细菌结合，而用大豆凝集素预孵育则无此作用。电子显微镜分析表明，鼠伤寒沙门氏菌在体外对Caco - 2细胞的初始附着涉及顶端微绒毛上糖萼的周边成分。这些结果表明，PNA识别的位于糖萼中的Galβ(1 - 3)GalNAc表位参与了鼠伤寒沙门氏菌与Caco - 2细胞之间的早期识别事件，并且单个上皮细胞之间糖基化模式的差异可能是鼠伤寒沙门氏菌细胞选择性附着的一个决定因素。
