CONICET | Buscador de Institutos y Recursos Humanos

In previous work we found in a mouse respiratory allergy model to ovoalbumin (OVA), that the intake of a probiotic fermented milk (PFM) lowers specific IgE and increases IgG (mainly IgG2a); also influences IL-10 and IFN-γ production in lungs. Our aim was to establish if the origin of the regulation observed was due to regulatory Tcells (Treg) or induction of Th1 balance. Adult BALB/c mice were split into 5 groups: Normal-Control(NC), Basal(B=5days-PFM), OVA-Sensitization-Control(SC), Previous (PT=5d-PFM+OVA+H2O) and Continuous feeding(CT=5d-PFM+OVA+PFM); SC, PT and CT were sensitized with 3 OVA injections and 7 days with OVA aerosols exposure. At 7 and 15 days-post-sensitization (dPS) and 2 days post-re-stimulus (dPR) mice were sacrificed; lymphocytes were purified from lungs to analyze CD4/CD25/Foxp3 markers for Treg cells by flow cytometry. Also, lungs tissue was reserved for confocal microscopy to study co-expression of CD4 Tcells with IL-10 and IFN-γ and for IL-12 production in lungs supernatant by ELISA. Treg cells were significantly reduced in the 3 sensitized groups in comparison with NC and B (p≤0.05) in all the studied times. Confocal microscopy studies showed that CD4+/IL-10+ cells in lungs were increased in SC and CT groups compared to NC; CD4+/IFN-γ+ cells were increased in those animals with continuous intake of PFM at 7dPS compared to NC and SC. IL-12 was increased in CT in all the studied times. We confirm that the regulatory mechanism to control allergy development was due to the induction of a Th1 balance instead of Treg cells but without exacerbating Th1 response. IL-12 levels activate Th1 cells to produce IFN-γ to inhibit IL-4 (Th2). These findings are relevant and they show how a PFM can help treating or preventing allergies and contributing to the nutritional state.