In addition, the DTH test was higher in treated mice compared with sensitized and placebo treated animals indicating the presence of specific Th1 cells. bowel cytokine and transcription factor gene expression) and systemic (specific isotypes and spleen cell-secreted cytokines) parameters, and skin assessments were done to evaluate the immune response. We found that the oral administration of U-Omp16 with CMP during sensitization dampened the allergic symptoms, with negativization of immediate skin test and increased skin DTH response. Serum specific IgE and IL-5 were inhibited and a Th1 response was promoted (specific IgG2a antibodies and CMP-induced IFN- secretion). We found at the mucosal site an inhibition of the gene expression corresponding to IL-13 and Gata-3, with an induction of IFN- and T-bet. These results indicated that this oral administration of U-Omp16 significantly controlled the allergic response in sensitized mice with a shift of the balance of Th1- and Th2-T cells toward Th1 predominance. These findings suggest that U-Omp16 may be useful as a Th1-directing adjuvant in an oral vaccine. Keywords: milk allergy, U-Omp16, oral adjuvant, IgE, immunomodulation, intestinal mucosa Introduction The hygiene hypothesis has been raised for more than 2 decades.1 Although conflicting results have been reported, it is generally accepted that some infections, especially intracellular bacterial and parasitic infections, may have a negative impact on the development of allergic and autoimmune diseases.2-4 The mechanism behind the hygiene hypothesis is believed to be related to immune deviation and/or immune regulation. Indeed, some bacterial infections have been found to alter an allergen-driven T helper 2 (Th2) -cell response to a T helper 1 (Th1)-dominated-cell response. The reduction of allergic reactions and Th2-cell responses was associated with enhanced Th1-cell response.5,6 Cows milk allergy (CMA), an immunological mediated reaction to cows milk proteins, is one of Protostemonine the most prevalent human food allergies, particularly in infants and young children.7 It is known that allergic disorders are mediated by T lymphocytes secreting Th2 cytokines, resulting in high levels of serum IgE with the risk of life-threatening anaphylaxis after a repeated exposure to the allergen. One of the corrective strategies explored to downregulate the Th2 effector immune response is the induction of a specific Th1 counter-acting immune response that controls the adaptive immunity and the clinical response to the offending allergen.8,9 So, a lower exposition to TLR ligands plus an increase exposition to allergens affect the immunologic homeostasis and influence the development of allergy. Many immunomodulatory strategies that use pro-Th1 adjuvants have been based on this hypothesis.10 The outer membrane protein of 16 kDa from (U-Omp16) is a new pathogen associated molecular pattern (PAMP) that activates dendritic cells (DCs) and has self-adjuvanting properties when administered by the oral or intraperitoneal route inducing protection against challenge. We found that these responses were TLR4 mediated.11 We Protostemonine also demonstrated that the nasal co-administration of U-Omp16 with the model antigen (Ag) ovalbumin (OVA) induced OVA-specific systemic IgG and Th1 immune responses. In addition, the power of U-Omp16 was also assessed in a mouse model of food allergy. The intranasal administration of U-Omp16 during the sensitization ameliorated the hypersensitivity response of sensitized mice upon oral exposure to cows milk proteins (CMP), reduced the clinical indicators, decreased anti-CMP IgE serum antibodies and modulated the Th2 response in Protostemonine favor of Th1 immunity.12 Among different Protostemonine mucosal routes, oral delivery is the most easy and acceptable way to administer a formulation, especially in children. Thus, the purpose of this study was to examine the U-Omp16 capacity to downregulate an allergen-specific Th2 immune response when it is administered as an adjuvant through the oral route. These findings may provide a novel therapeutic approach for allergic diseases. Results The oral administration of U-Omp16 with Protostemonine CMP controls the Mouse monoclonal to SORL1 induction of allergy To study the adjuvant capacity of U-Omp16 in an oral formulation, mice were intragastrically (i.g.) administered with U-Omp16 during the sensitization phase and the induction of an allergic reaction was analyzed. As control, a group of mice received CpG (Th1 adjuvant) with CMP by gavage, another group of mice received only CMP (no sensitization) and OVA was used as a non-related antigen (Fig.?1A shows a schematic representation of the experimental protocol). An oral challenge following the sensitization phase was performed to evidence the induction of hypersensitivity reactions immediately after the exposure to the allergen. The clinical signs were scored (Fig.?1B) and we evidenced that treated animals (Sens/Omp16 and Sens/CpG) showed significant lower clinical scores compared with sensitized animals exposed.