Milk fermented by Lactobacillus helveticus R389 and its non-bacterial fraction confer enhanced protection against Salmonella typhimurium infection in mice.

VINDEROLA, C.G.; MATAR, C.; PERDIGÓN, G.

Buenos Aires

Congreso; III Congreso Argentino de Microbiología de Alimentos; 2006

Asociación Argentina de Microbiología

Bacterial infections in the gastrointestinal tract represent a major global health problem, even in the presence of normally effective mucosal immune mechanisms. In a previous work, we observed that milk fermented by Lactobacillus helveticus R389 (FM) or its non-bacterial fraction obtained by milk fermentation at pH 6-controlled (NBF) are able to activate the small intestine mucosal immune response [1]. In this work we aimed at comparing their protection capacity against a Salmonella enteritidis serovar Typhimurium infection and we also aimed at studying the mechanisms involved. BALB/c mice received FM or NBF for 2, 5 or 7 consecutive days, followed by a single oral challenge with Salmonella enteritidis serovar Typhimurium (107 cells/mouse). The increase in the number of IgA+ cells in the lamina propria of the small intestine, after the feeding periods with FM or its NBF, was accompanied by an increase in the luminal content of total S-IgA. However, no antibodies were produced against the NBF. Electron microscopy studies showed that both L. helveticus R389 and Salmonella enteritidis serovar Typhimurium were able to interact with small intestine epithelial cells isolated from mice and no competitive exclusion was observed for them. In mice given the FM or the NBF for 7 consecutive days, lower levels of liver colonization on day 7 post-challenge with Salmonella enteritidis serovar Typhimurium, higher luminal contents of specific anti-Salmonella S-IgA, higher percentages of survival to infection and lower numbers of MIP-1a+ cells in the lamina propria were observed. In this work we observed that in the FM or in the NBF there are active principles that confer enhanced protection against Salmonella enteritidis serovar Typhimurium infection. However, the mechanisms underlying mucosal immunomodulation and protection are different. In those mechanisms, the mucosal immune response would seem to be more involved than the competitive or exclusion mechanisms between L. helveticus R389 and Salmonella enteritidis serovar Typhimurium.