Partially purified soy hydrolysates retard proliferation and inhibit bacterial translocation in cultured C2BBe cells

Abstract

Hydrolyzed soybean isolates SP-A and SP-B (Abbott Laboratories, OH), developed for use in enteral nutritional products, were tested in cultures of C2BBe cells, a colonic adenocarcinoma cell line with enterocytic differentiation, to evaluate effects on cell growth, maturation and ability to resist infection by enteric bacteria. SPA delayed formation of confluent monolayers by 10 d compared with cells cultured without SP-A. SP-A also caused a retardation in the development of intercellular tight junctions as measured by transmonolayer electrical resistance (TER). SP-B had no effect on cell proliferation or TER of intestinal cell cultures. SP-A and SP-B enhanced the development of the brush border enzymes alkaline phosphatase and isomaltose over a 28 d period. By these criteria, SP-A and SP-B appear to affect intestinal epithelial cell development in culture. When C2BSe monolayers were exposed to the enteric bacteria, Salmonella typhimurium or Salmonella typhi, an inhibition of the passage of S. typhi was seen in cultures with SP-A and SP-B. No effect on the passage of S. typhimurium was seen with either soy isolate. Partially purified soy isolates therefore impart resistance to selected enteroinvasive bacteria. Addition of soy hydrolysates to the media of cultured intestinal cells may serve as a rapid and economical screening mechanism for preclinical trials that would test the therapeutic benefits of soybean isolates.