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

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

IMMUNOBIOLOGY.

Elsevier

Año: 2007 vol. 212 p. 107 - 118

0171-2985

Bacterial infections in the gastrointestinal tract represent a major global health problem, even in the presence ofnormally effective mucosal immune mechanisms. Milk fermented by Lactobacillus helveticus R389 (FM) or its nonbacterialfraction obtained by milk fermentation at controlled pH 6 (NBF) are able to activate the small intestinemucosal immune response according to previous studies. In this work we aimed at comparing their protection capacityagainst an infection by Salmonella enteritidis serovar Typhimurium and at studying the mechanisms involved. In acompletely randomized design, BALB/c mice received FM or NBF for 2, 5 or 7 consecutive days, followed by a singleoral challenge with S. Typhimurium (107 cells/mouse). The increase in the number of IgA+ cells in the lamina propriaof the small intestine, after the feeding periods, was accompanied by an increase in the luminal content of total S-IgA.However, no antibodies were produced against the NBF. In mice given the FM or the NBF for 7 consecutive days,lower levels of liver colonization on day 7 post-challenge with S. Typhimurium, higher luminal contents of specificanti-Salmonella S-IgA, higher percentages of survival to infection and lower numbers of MIP-1a+ cells in the laminapropria were observed. In this work we observed that in both the FM or the NBF there are active principles that conferenhanced protection against S. Typhimurium infection. However, the mechanisms underlying mucosal immunomodulationand protection are different. In those mechanisms, the mucosal immune response would seem to be moreinvolved than the competitive or exclusion mechanisms between L. helveticus R389 and S. enteritidis serovarTyphimurium.