Immune mechanisms induced by fermented milk containing the probiotic strain L. casei DN-114001 in the protection of Salmonella enteritidis serovar Typhimurium infection

C. MALDONADO GALDEANO; A. DE MORENO DE LEBLANC; E. CARMUEGA; R. WEILL; G. PERDIGON

Lisboa, Portugal

Congreso; Vaccines for enteric diseases; 2007

Bacterial infections in the gastrointestinal tract represent a mayor global health problem ever in the presence of normally effective mucosal immune mechanisms. Salmonella serotypes and enterohemorhagic E. coli are the most important microorganisms causing diarrhea in the world. Salmonella are associated with three different human disease syndromes, bacteriemia, typhoid fever and enterocolitis. Mouse septicemia after the challenge with Salmonella enteritidis serovar Typhimurium (S. Typh.) is considered a reasonable reflection of typhoid fever in S. Typhimurium infected humans (1). Salmonella enteritidis serovar Typhimurium is an invasive bacteria and the pathway of internalization is through the M cell of the Peyer’s patches or M cells of the villi intestine to invade the immune cells associated to the gut and to disseminate toward deep tissues and to cause diarrhea disease. It is now clear that the host play an important role in the defense against the pathogen, and the gut mucosal immunity play a key role to stop the Salmonella dissemination. Oral adjuvant that improves gut mucosal immunity would be a good tool to increase the intestinal barrier against enterobacteria or in reducing the infection against enteropathogen. Probiotic bacteria especially from lactic acid bacteria or fermented milk containing probiotics have adjuvant effects on gut mucosal immunity (2), and some probiotics have been reported to be useful in the treatment of disturbed intestinal microflora and diarrheic diseases (3). For Salmonella infection, Gill et al. (4) reported that selected probiotic strains conferred resistance against Salmonella enteritidis infection. Other studies from our laboratory showed that a fermented milk with probiotic bacteria was effective in the prevention of enteroinvasive E. coli infection (5). This milk fermented with L. bulgaricus, S. thermophillus and L. casei was able to activate the small intestine mucosal immunity (6). The use of fermented milks instead of probiotic bacteria suspensions has the advantage that, beside of the oral adjuvant effect of bacteria, milk is a rich source of proteins or biologically active peptides and oligosaccharides which appear to play protective role against infections.