Preliminary studies on the prevention of the ovalbumin-induced allergic response by Enterococcus faecalis CECT7121 in mice.

BACKGROUND

Allergic diseases are featured by an increased production of IgE due to an imbalance in the immune response towards a Th2 profile. In this work, the ability of Enterococcus faecalis CECT7121 to regulate this Th2-exaggerated response in a murine model of ovalbumin (OVA)-induced allergy was studied.

METHODS

BALB/c mice intragastrically inoculated with E. faecalis CECT7121 before and during a subcutaneous immunization protocol with OVA were studied in comparison with an immunized control group. The allergen-specific immune response (IgE, IgG, IgG1 and IgG2a) was assessed. The proliferative activity of memory splenocytes and the levels of IL-4, IL-5, IL-13, IL-10, IL-12 and IFN-γ were also determined.

RESULTS

Upon treatment with E. faecalis CECT7121 the following effects were observed: (1) a decrease in specific IgE levels, (2) an increase in anti-OVA IgG2a levels, (3) the levels of anti-OVA IgG and IgG1 remained unaltered, (4) a reduction in the proliferation rate of memory cells, (5) a decrease in the levels of the Th2 cytokines IL-4, IL-5 and IL-13, and (6) the secretion of IL-10, IL-12 and IFN-γ remained unchanged. Moreover, the incubation of human basophils with non-viable E. faecalis CECT7121 together with an allergen preparation induced the release of β-hexosaminidase at levels that were lower than control reactions and similar i.g. the spontaneous release.

CONCLUSIONS

In this model, the i.g. administration of E. faecalis CECT7121 hampers the establishment of the OVA-induced allergic immune response, suggesting that this strain could be useful for the treatment of IgE-mediated allergic diseases.