Oral Administration of Bacterial Lysates Attenuates Experimental Food Allergy

Background: Modulating early immune response by application of bacteria and their by-products has been suggested as a preventive strategy against the development of allergic diseases. In light of this, the aim of the study was to test the effects of oral administration of bacterial lysates (BL) in a rat model of food allergy. Methods: BL or PBS were administered orally to neonatal Brown Norway rats up to an age of 42 days. Additionally, animals were sensitized 3 times (days 35, 40 and 45) intraperitoneally with ovalbumin (OVA). On days 60 and 61, rats were locally challenged with OVA by gavage feeding. Results: Detection of increased allergen-specific Ig serum levels and proliferative responses of spleen mononuclear cells confirmed systemic sensitization. In serum of animals that received BL in addition to OVA sensitization, the levels of allergen-specific IgE and IgG were significantly reduced compared to animals which were not exposed to BL. Allergen-stimulated lymphocytes from spleen and mesenteric lymph nodes of BL-treated animals showed a significantly elevated cytokine production of IL-10. To assess local functional changes of the intestinal barrier we measured the intestinal permeability, which was increased in OVA-sensitized and challenged animals compared to non-sensitized controls, yet significantly reduced in sensitized animals which received BL. Conclusion: These data suggest that local administration of BL (pathogen-associated molecular patterns) in the intestine exhibits immuno-modulating effects. Furthermore, pathophysiological features of food allergy, such as the loss of gut mucosal integrity, might be reduced by the treatment with BL. Copyright (C) 2011 S. Karger AG, Basel