Helander A, Hansson G C, Svennerholm A M
Department of Medical Microbiology and Immunology, Göteborg University, Guldhedsgatan 10A, Göteborg 413 46, Sweden.
Microb Pathog. 1997 Dec;23(6):335-46. doi: 10.1006/mpat.1997.0163.
Binding of human enterotoxigenic Escherichia coli (ETEC) to the small intestine is a prerequisite for colonization and is mediated by colonization factor (CF) antigens. Coli surface antigen 6 (CS6) is considered a CF but binding to isolated enterocytes has not been established. In this study bacteria expressing CS6 were analysed for binding to enterocytes from human and rabbit small intestine, isolated using either an EDTA-containing buffer or a buffer devoid of EDTA. We found that the bacteria bound to enterocytes from rabbit ileum and human duodenum, but only when the cells had been isolated in the absence of EDTA. Pretreatment of rabbit enterocytes with meta-periodate resulted in a decreased proportion of cells with bound bacteria. Purified CS6, and for comparison other ETEC CFs, were also tested for binding to different human and rabbit mucus fractions. These analyses showed that purified CS6 bound to mucus from rabbit duodenum and ileum as well as from human duodenum, jejunum and ileum and that this binding was abolished by pretreatment of the mucus material with meta-periodate or Proteinase K. CFA/I, CS1 to CS5, CS7, CS17, putative CF (PCF) O159 (CS12), PCFO166 (CS14), and CFA/III (CS8) also bound to the rabbit mucus material although with different patterns; the binding of CS2 and CS5 was abolished by meta-periodate treatment. Thus, ETEC bacteria expressing CS6 might bind to carbohydrate-containing structure(s) in the apical membrane of isolated rabbit ileal and human duodenal enterocytes that could probably be released by EDTA treatment. In addition, CS6 and other ETEC CFs bind to component(s), in some instances protein-associated carbohydrate structures, in mucus fractions from small intestine.
人肠产毒性大肠杆菌（ETEC）与小肠的结合是定植的前提条件，由定植因子（CF）抗原介导。大肠杆菌表面抗原6（CS6）被认为是一种CF，但尚未证实其与分离的肠上皮细胞的结合。在本研究中，分析了表达CS6的细菌与来自人和兔小肠的肠上皮细胞的结合情况，这些肠上皮细胞是使用含EDTA的缓冲液或不含EDTA的缓冲液分离得到的。我们发现，细菌与兔回肠和人十二指肠的肠上皮细胞结合，但仅当细胞在无EDTA的情况下分离时才会发生。用偏高碘酸盐预处理兔肠上皮细胞会导致结合细菌的细胞比例降低。还测试了纯化的CS6以及作为对照的其他ETEC CF与不同人和兔黏液组分的结合情况。这些分析表明，纯化的CS6与兔十二指肠和回肠以及人十二指肠、空肠和回肠的黏液结合，并且这种结合可通过用偏高碘酸盐或蛋白酶K预处理黏液材料而被消除。CFA/I、CS1至CS5、CS7、CS17、推定CF（PCF）O159（CS12）、PCF O166（CS14）和CFA/III（CS8）也与兔黏液材料结合，尽管结合模式不同；CS2和CS5的结合可通过偏高碘酸盐处理而被消除。因此，表达CS6的ETEC细菌可能与分离的兔回肠和人十二指肠肠上皮细胞顶端膜中含碳水化合物的结构结合，这些结构可能可通过EDTA处理释放出来。此外，CS6和其他ETEC CF与小肠黏液组分中的某些成分（在某些情况下是与蛋白质相关的碳水化合物结构）结合。
