HIGHER GASTRIC IL-10 LEVELS IN H. PYLORI-POSITIVE CHILDREN THAN ADULTS MAY NOT BE ATTRIBUTED TO T_REGFOXP3 CELLS

Fabrício Freire de Melo (ICB/UFMG); Gifone Aguiar Rocha (F. Medicina/UFMG); Andreia Maria Camargos Rocha (F. Medicina/UFMG); Bárbara Aparecida Chaves (ICB/UFMG); Silvia Helena Souza Pietra Pedroso (F. Medicina/UFMG); Lúcia Porto Fonseca de Castro (F. Medicina/UFMG); Paulo Bittencourt (HC/UFMG); Simone Diniz Carvalho (HC/UFMG); Rodrigo Corrêa-oliveira (Fiocruz/MG); Dulciene Maria de Magalhães Queiroz (F. Medicina/UFMG)

The immune response to Helicobacter  pylori is more modulated in children than in adults, which has been attributed to increased T_reg cells in children. Therefore, we evaluated the effect of H. pylori infection in children (n=200) and compared infected children and adults (n=100) regarding to gastric pro-inflammatory and T_reg commitment (IL-2, IL-10 and TGF-b) cytokines. Gastric cytokine levels were assessed, in duplicate, by ELISA (Biosource, Camarillo, CA) and the results were expressed as picograms of cytokine per milligram of biopsy protein (pg/mg protein). T_regFoxp3 cells were also assessed on the antral and corpus mucosa by immunoperoxidase.  Although all cytokine mean levels were much higher in H. pylori-positive than in -negative children (p<10^-3 for all), the increase of pro-inflammatory cytokines of the innate immune arm (IL-6, IL-12p70 and TNF-a) and of regulatory cytokine (IL-10) was more remarkable (fold increase > 33.3). Cytokine levels of the innate (IL-1a, 1L-6 and TNF-a), modulatory (IL-10) and Th2 (IL-4) response (p< 10^-3 for all) were higher and the levels of IL-1b(p<10^-3), IL-2(p=0.02), IL-17(p=0.003), IL-23(p=0.04) and IFN-g(p=0.01) were lower in children than in adults, but TGF-b(p=0.23) did not differ. The T_regFoxp3 cell median number was higher in H. pylori-positive than –negative children (p=0.001); however, it did not differ in the antrum (p=0.63), but was decreased in the corpus (p=0.03) of children compared to adults. Concluding, although IL-10 level is higher in infected children than in adults (6.1 fold), this may not be attributed to T_reg cells, because their number and associated cytokines were similar in children and adults. Since innate immunity is strongly activated in children, we may propose dendritic cells/macrophages as an alternative IL-10 source. (CNPq/CAPES/FAPEMIG)