Modulation of gut immune response by probiotic fermented milk consumption to control IgE in a respiratory allergy model.

Allergies are a world increasing health issue and most treatments are oriented to alleviate symptoms. Probiotics have several health benefits including the improvement of the immune system. In previous work we found that consumption of commercial probiotic fermented milk (PFM) significantly reduced specific-immunoglobulin (Ig) E in serum and lungs by increasing specific-IgG and controlled allergic response to ovalbumin (OVA) in an adult mouse respiratory allergy model. Here we continued our study determining the mechanism triggered in the gut by the PFM ingestion that influenced the results previously reported. Five groups of BALB/c mice were assessed: normal-control, basal (drinks PFM five days without OVA sensitisation), sensitisation-control (no PFM intake), previous and continuous-PFM administration. Allergen administration: 3 OVA injections (1% in PBS) followed by aerosols exposure for 7 days. We determined total secretory-IgA and cytokines in small intestine (SI) fluid; CD11b+, CD103+, IgA+ cells and cytokine producing cells in SI tissue. In lungs we analysed co-expression of CD4/interferon (IFN)-γ or CD4/interleukin (IL)-10, IgE+ cells and IL-12 production. Results: continuous intake of PFM increased the expression of CD103 marker and decreased CD11b and pro-inflammatory cytokines. Coexpression of CD4/IFN-γ was confirmed in lungs of animals that consumed PFM continuously. This group had a lower count of IgE+ cells and a higher concentration of IL-12. The consumption of PFM reinforces the mucosal barrier by increasing IgA+ cells and induces signalling from the intestine to the lungs by increasing the expression of CD103+ dendritic cells related to regulatory mechanisms. The results found in this work together with those previously reported demonstrated that the intake of PFM induces a clear balance towards the Th1 response, preventing the Th2 allergic response by controlling the previously reported IgE level. According to our model, the intake of PFM could be a good strategy to alleviate the development of allergies.

Adjuvant effect of a probiotic fermented milk in the protection against Salmonella enteritidis serovar typhimurium infection: mechanisms involved.

Probiotics may offer protection against Salmonella enteritidis serovar Typhimurium infection via different mechanisms. The aim of this study is to investigate, using mouse models, the effect of the administration of fermented milk containing the probiotic bacteria L. casei DN-114 001 in the protection against Salmonella enteritidis serovar Typhimurium when this product is administered continuously before and after infection or only post-infection. The adjuvant effect of this probiotic fermented milk (PFM) against S. Typhimurium was also evaluated in newborn mice, whose mothers received the PFM during the suckling period or their offspring after weaning. The results obtained showed that PFM administration after salmonella infection was useful to decrease the severity of the infection. The best effect was obtained with continuous PFM administration. In the newborn mice model, PFM administration to the newborn mice after weaning showed the best effect against the pathogen. PFM administration to the mother during the suckling period was beneficial against this enterophatogen when their offspring did not receive probiotics after weaning. Continuous PFM administration to adult mice (before and after infection) was important to maintain the intestinal barrier and the immune surveillance in optimal conditions to diminish the pathway of entrance of salmonella and the spread of this pathogen to deeper tissues. In the newborn mice model, it was observed that PFM administration to the offspring after weaning or their mother during the suckling period had a protective effect against salmonella infection, however, in the mice from mothers that received PFM during nursing which were fed with PFM after weaning, we found a down regulated immune maturity that was not protective against this infection.

Interaction of lactic acid bacteria with the gut immune system.

Health claims of lactic acid bacteria (LAB) used in functional foods and pharmaceutical preparations are based on the capacity of these microorganisms to stimulate the host immune system. In this study, the antigenic effect of LAB (Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus) on the gut immune system of BALB/c mice was evaluated. A dose-dependent increase of the Bcl2 protein was observed with all LAB assayed. Furthermore, the analysis of cytokine-producing cells in the lamina propria of gut showed that TNFalpha and INFgamma values, determined in macrophages cultured from Peyer patches, were enhanced for all the LAB assayed. An important increase of interleukins IL-10 and IL-4 was observed mainly in mice fed with Lactobacillus delbrueckii ssp. bulgaricus or Lactobacillus casei, while a significant induction of IL-2 and IL-12 was only observed with L. acidophilus (P<0.01). These effects were dose dependent. The role of produced cytokines in the balance Th1/Th2 was determined by a systemic antibody response against parenterally injected ovoalbumin. L. casei, L. delbrueckii ssp. bulgaricus and L. acidophilus enhanced the IgG1 response favouring Th2 balance, while L. acidophilus also increased the IgG2a response inducing Th1 balance. S. thermophilus did not influence the balance Th1/Th2. Our studies showed that lactic acid bacteria induce distinct mucosal cytokine profiles showing different adjuvant capacity among them. Thus, selection of probiotic strain with immunological properties must be well defined to influence cytokine expression that favour the claimed immune response.