Immunomodulatory properties of Brucella abortus U-OMP 16 in a food allergy mouse model

SMALDINI PAOLA; IBAÑEZ ANDRES; FOSSATI CARLOS; CASSATARO JULIANA; DOCENA GUILLERMO

BUENOS AIRES

Congreso; Primer Congreso Franco-Argentino FAIC, LVIII Jornada Científica del Grupo Rioplatense de Citometría de Flujo y Tercer Jornadas Argentinas de Inmunodeficiencias Primarias; 2010

SAI Y SOCIEDAD FRANCESA DE INMUNOLOGIA

Immunomodulation constitutes a potential therapy for food allergy. It has been reported that OMP 16 from Brucella abortus produced a Th1 in vitro and in vivo immune response in mice immunized by oral or intraperitoneal routes. The aim of this work was to use OMP16 as a mucosal immunomodulator in a cow`s milk allergy mouse model. Balb/c mice were intragastrically immunized with cow`s milk protein (CMP) using cholera toxin (CT) as a Th2 mucosal adjuvant. Mice were simultaneously treated with recombinant unlipidated OMP16 intranasally (U-OMP16 in), with U-OMP16 intragastrically (OMP ig), with E. coli LPS in (control group), with synthetic ODN CpG ig (control group) or with saline (control group). Finally, mice were orally challenged with CMP. Immune response was evaluated with in vitro (serum specific IgE, IgG1 and IgG2a, histamine, IL-5 and IFN-ã secretion by splenocytes) and in vivo assays (clinical score, cutaneous tests and DTH). IL-5 and IFN-ã mRNA expression was assessed in intestinal tissue. We found lower clinical scores and plasma histamine levels in treated mice after the oral challenge than in sensitized animals. Cutaneous tests were positive in sensitized mice, while negative or mild in the treated groups. DTH was statistically higher in OMP 16 and LPS treated animals (0.20±0.07; 0.16±0.09 vs 0.74±0.04, p<0.05). Besides, specific IgE was suppressed [1.06±0.30 vs 0.54±0.21 (OMP), 0.22±0.2 (LPS); 0.87±0.23;0.45±0.18 (CPG)], while IgG2a was increased, in treated mice. IL-5 and IFN-ã were modulated by the different immunomodulators at the protein and mRNA levels. In conclusion, OMP 16 of Brucella abortus, LPS and CpG, were found to modulate the specific Th2 immune response elicited with CMP plus CT, by mucosal administration in Balb/c mice. These results may constitute the basis for a potential immunomodulatory therapy in food allergy.