Treatment with <i>Enterococcus faecalis</i> CECT7121 Is Not Effective as Therapy in Mice with an Established Allergy Status

Abstract

In allergies, an unbalanced immune response towards a T helper (Th) 2 profile with high levels of Immunoglobulin (Ig) E is produced. We have demonstrated that the pre-administration of Enterococcus faecalis CECT7121 prevents the development of allergy in ovalbumin-immunized mice. In this work, we evaluated whether this bacterium can also revert an established allergic status. Mice were immunized with ovalbumin (OVA) and after that, were inoculated with an E. faecalis CECT7121 suspension. In immunized animals, serum specific immune response, proliferative activity of memory splenocytes, and levels of Th2 cytokines were assessed. The in vivo active cutaneous anaphylaxis test was also performed. The treatment with E. faecalis CECT7121 only increased anti-OVA IgG2a levels. No differences were observed in other specific immunological parameters. Probiotic-treatment did not prove to have any desensitizing effect on mice. These results, together with those recently published, can be concluded that this bacterium would not be appropriate for the treatment of allergic symptoms.