Lentils and Yeast Fibers: A New Strategy to Mitigate Enterotoxigenic Escherichia coli (ETEC) Strain H10407 Virulence?

Abstract

Dietary fibers exhibit well-known beneficial effects on human health, but their anti-infectious properties against enteric pathogens have been poorly investigated. Enterotoxigenic Escherichia coli (ETEC) is a major food-borne pathogen that causes acute traveler’s diarrhea. Its virulence traits mainly rely on adhesion to an epithelial surface, mucus degradation, and the secretion of two enterotoxins associated with intestinal inflammation. With the increasing burden of antibiotic resistance worldwide, there is an imperious need to develop novel alternative strategies to control ETEC infections. This study aimed to investigate, using complementary in vitro approaches, the inhibitory potential of two dietary-fiber-containing products (a lentil extract and yeast cell walls) against the human ETEC reference strain H10407. We showed that the lentil extract decreased toxin production in a dose-dependent manner, reduced pro-inflammatory interleukin-8 production, and modulated mucus-related gene induction in ETEC-infected mucus-secreting intestinal cells. We also report that the yeast product reduced ETEC adhesion to mucin and Caco-2/HT29-MTX cells. Both fiber-containing products strengthened intestinal barrier function and modulated toxin-related gene expression. In a complex human gut microbial background, both products did not elicit a significant effect on ETEC colonization. These pioneering data demonstrate the promising role of dietary fibers in controlling different stages of the ETEC infection process.

A flow cytometry method for quantitative measurement and molecular investigation of the adhesion of bacteria to yeast cells

“…This suggestion is based on the finding that bacterial adhesion to intestinal mucosa is achieved by glycoproteins abundantly present in the membrane of these host cells carrying N-linked mannose structures that bind to bacterial mannose-specific type 1 fimbriae [9][10][11] . As yeast cell wall are enriched with proteins highly decorated with mannosyl sugars that represents about 40% of the cell wall mass 12,13 , these components can act as antagonist to mannosyl-sugars of the host glycoproteins 14,15 . However, bacteria adhesion to intestinal cells can also occur by other means, such as by afimbrial autotransporter (AT) adhesins that are present among Enterobacteriaceae family of the Escherichia genus 16 , or Tia produced by some enterotoxigenic E. coli (ETEC) 17 .…”