Concanavalin A Promotes Adherence of Salmonella typhimurium to Small Intestinal Mucosa of Rats

Abstract

A number of dietary lectins have been shown to resist proteolytic digestion. These lectins interact with the small intestinal mucosa causing structural and functional changes. Concomitant to these changes, bacterial overgrowth was reported and a possible interaction between lectins and bacteria in the small intestine was postulated. The aim of this study was to investigate the effect of various lectins on adherence of Salmonella typhimurium to both isolated small intestinal enterocytes and ligated intestinal loops. Isolated intestinal cells or ligated intestinal loops were incubated with ['HI adenine-S. typhimuriurn in the presence or absence of concanavalin A, phytohemagglutinin, peanut agglutinin, and wheat germ agglutinin. Only concanavalin A promoted the adherence of various strains of nonfimbriated S. typhimurium to isolated viable intestinal cells. Other lectins showed no effect on the adherence. In situ studies showed that bacterial binding was increased in concanavalin A-treated intestinal loops, supporting the significance of the experiments in vitro. These data suggest that lectins may act by promoting bacterial adherence to the small intestine, thereby facilitating colonization and infection, and leading to bacterial overgrowth. [P.S.E.B.M. 1989, Vol1921he widespread presence of lectins in dietary foods has prompted a number of investigators to ex-

Modulation of Salmonella infection by the lectins of Canavalia ensiformis (Con A) and Galanthus nivalis (GNA) in a rat model in vivo

“…1995 ). Con A has been shown to increase Salmonella numbers in the rat in situ ( Abud et al . 1989 ).…”

“…Since Con A aggregated Salmonella strains and was also found to increase the attachment of Salm. typhimurium to gut epithelium in situ ( Abud et al . 1989 ), the effects of Con A on gastrointestinal infection merited study.…”

“…typhimurium and glycoproteins on the enterocyte ( Alexander 1981). For example, afimbriate bacteria were shown to bind to Con A‐agarose beads in vitro ( Abud et al . 1989 ).…”

“…1995 ). However, Con A has been found to promote adherence of Salmonella to isolated viable intestinal cells and to promote adherence to intestinal loops ( Abud et al . 1989 ).…”

Nutritional Influences on Interactions Between Bacteria and the Small Intestinal Mucosa

“…It is conceivable that other mannose specific lectins present in foodstuffs which are more regularly consumed (by humans) may also have beneficial effects and, in this context, lectins from garlic (Kaku et al 1992), shallots (Mo et al 1993) and BanLec-1 from bananas (Koshte et al 1990) may hold particular interest. It may be appropriate to sound a cautionary note against the universal application of the concept in view of the reported enhancement of adherence of non-fimbriated Salmonella typhimurium to rat small intestine by concanavalin A (Abud et al 1989); here the authors suggest that colonization may be promoted by the formation of lectin bridges between the bacterial and mucosal cell surfaces.…”