CONICET | Buscador de Institutos y Recursos Humanos

Numerous studies have proposed the use of probiotics to improve gut health, especially in the protection against enteropathogens. Between them, Salmonella spp. constitutes one of the principal causative agents of poisoning and food borne disease in the world. We investigated the biological and immune mechanisms clues for a probiotic strain, to confer protection against Salmonella (S.) Typhimurium infection. To achieve this goal, we compared the effect of three different lactobacilli strains: Lactobacillus (L.) casei CRL 431, L. delbrueckii subsp. bulgaricus CRL 423 and L. acidophilus CRL 730. Our results showed that L. casei CRL 431 was the only strain with protective skills against Salmonella. The continuous treatment with this strain improved animal survival, and diminished pathogen counts in liver, spleen and large intestine. Also L. casei CRL 431 increased the number of IgA(+) cells in lamina propria, as well as total and specific S-IgA in intestinal fluids. Increased IgA levels correlated with the increased IL-6 levels observed for this group. Before the infection, L. casei activated peritoneal, Peyer?s patches and spleen macrophages through activation of phagocytosis process, and post infection through increased expression and secretion of IFNγ. The probiotic bacterium also attenuated the intestinal inflammation by reducing tissue damage and polymorphonuclear infiltration, and maintaining the levels of the regulatory cytokine, IL-10. Although L. acidophilus CRL 730 increased the number of IgA(+) cells previous and post infection, and L. bulgaricus CRL 423 increased phagocytic activity of macrophages, these mechanisms alone, were not sufficient to confer protection against S. Typhimurium infection in mouse.

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