CONICET | Buscador de Institutos y Recursos Humanos

Nutritional habits, reduced exposure to microorganisms in childhood and indiscriminate use of antibiotic provoke changes in the intestinal microbiota, which has an essential role in the maturation and function of the immune system. Changes in the microbiota, together with genetic factors induce the development of allergy with a typical Th2 profile. It was reported the beneficial effect of probiotics in disease, however the mechanisms involved are not well understand yet. Several studies have shown that probiotics can stimulate the mucosal immune system and improve the composition of the microbiota, in this regard it was demonstrated that the microbiota of allergic children is different from the non-allergic, hence the administration of probiotics is proposed to avoid the development of allergies by balancing the microbiota. Orally administered probiotics induce modulation of the immune system not only at the intestinal mucosa, but also in other mucosal sites (such as bronchus) and at systemic level. The aim of this work is to evaluate the adjuvant immune effect of the oral administration of a probiotic fermented milk (PFM) in the intestinal mucosa and the extent of these effects to distant mucosal sites (bronchus) in an experimental mouse model of allergic airway reactivity to ovoalbumin (OVA). Experimental groups: normal-control (NC), Basal (B-5days-PFM); OVA-Sensitization-control (SC), Previous (P) (5d-PFM+OVA+H2O) and Continuous (C) (5d-PFM+OVA+PFM). SC, P and C were sensitized with OVA 1% followed by daily exposures to OVA aerosols. At 7 and 15 days post-sensitization (dps) we analyzed: specific-IgE, specific-IgG and IL10 in serum, total S-IgA, IL10 and IFNg in intestinal fluid (IF), specific- IgE in bronchoalveolar lavage (BAL) by ELISA. Determination of the number of IgA +, IL10 + and IL4 + cells in the lamina propria of small intestine (SI) and lungs by immunofluorescense assay. In large intestine (LI) we determine total populations of total anaerobes, lactobacilli, bifidobacteria and enterobacteria in selective media. Specific IgE was reduced in treated groups with regard to SC group in serum and BAL (DO 450nm) (0,38 ± 0,17 vs. 0,21 ± 0,07; 0,13 ± 0,01 vs. 0,23 ± 0,14 in serum and 0,52 ± 0,22 vs. 0,13 ± 0,03; 0,12 ± 0,01 vs. 0,13 ± 0,01 at 7 and 15 dPS). Specific IgG increased in all groups but had higher values in C (NC 0,06 ± 0,01 vs. B 0,08 ± 0,03 and 0,78 ± 0,10 vs. 0,80 ± 0,05 vs. 1,03 ± 0,07 for 7 dPS and 0,67 ± 0,06 vs. 0,65 ± 0,13 vs. 0,92 ± 0,10 for 15 dPS ? SC, P and C respectively). IL10 values increased only in SC group in SI fluid compared to treated groups, bat had no changes in serum (999,97 ± 19,18 vs. 709,66 ± 41,00 and 1299,13 ± 185,27 vs. 845,18 ± 87,50 for 7 and 15 dPS respectively). IFNg had no significant difference between groups in SI fluid. Total S-IgA from SI fluid significantly increased in CS a P groups compared to NC, B and C groups. IL4 + cells increased significantly in SC group in lungs with regard to the other groups at 7 and 15 dPS; in SI we found no differences between controls and treated groups. The number of IL 10 +cells was significantly higher in the lamina propria of SI from SC group compared to P and C at 7 and 15 dPS. With regard to the intestinal microbiota we found that the PFM induced a decrease of enterobacteria and increase of bifidobacteria only in C group, other populations were not affected. PFM was able to reduce the levels of specific IgE in serum and BAL in mice with continuous treatment; this could be mediated by the regulation of the intestinal microbiota that might have influence on the expression of cytokines IL4 (Th2 type) and IL10 (regulatory cytokine) at the mucosal level (intestine and lungs). However systemic and mucosal normal immune response was not affected because IgG and S-IgA production was not altered by the IL10.

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