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.
Highlights
In most individuals suffering from allergic diseases, an imbalance of the immune response towards a Th2 cytokine profile is observed
We have demonstrated that the pre-administration of Enterococcus faecalis CECT7121 prevents the development of allergy in ovalbumin-immunized mice
Probiotic bacteria can induce immune regulation or immune tolerance in allergic diseases as it had been demonstrated in a β-lactoglobulin-induced intestinal anaphylaxis in a murine model of food allergy where the oral administration of Clostridium butyricum CGMCC0313-1 ameliorated intestinal anaphylaxis symptoms and shifted the immune balance towards Th1 and Treg, with significantly increased Foxp3/Rorγt and Foxp3/Gata ratios and a significantly decreased Gata3/Tbet ratio [14]
Summary
In most individuals suffering from allergic diseases, an imbalance of the immune response towards a Th2 cytokine profile is observed According to the hygiene hypothesis [5] [7] [8] [9], the exposition to microorganisms during the early stages of life could revert this Th2-skewed response, and in turn, it could induce the development of a Th1 phenotype and stimulate the activity of Treg cells This observation has led to the experimental use of microorganisms to prevent or inhibit allergic diseases, being the probiotics, the most promising tool for this purpose [10]. Yang et al have observed that the treatment for two weeks with Bifidobacterium infantis during OVA sensitization attenuated the serum specific IgE and IgG1 secretion as well as reduced Th2-type cytokines in spleen cell supernatants and, after challenge with OVA, probiotic-treated mice showed lower allergic reaction measured as diarrhea than sensitized-mice [15]
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