Atividade probiótica de Bifidobacterium animalis e Lactobacillus casei na imunomodulação e na aderência de Escherichia coli enteroagregativa (EAEC) em células intestinais Caco-2

Abstract

Enteroaggregative Escherichia coli (EAEC) is an E. coli pathotype that characteristically shows aggregative adhesion pattern on in vitro cultured cells, mainly related to persistent infant diarrhea cases. Probiotics are non-pathogenic living microorganisms that confer health benefits. These organisms usually provide protection against pathogens, living naturally in microbiota and are often found in fermented foods such as dairy products. Probiotic bacteria have activity against foodborne pathogens, being able to promote biofilm formation reduction, inhibition of adhesion and injury of in vitro cultured cells, in vivo models diarrhea prevention and also immunomodulation. In this study, two bacterial species probiotic activity on the virulence of EAEC strains was evaluated. Probiotic species Bifidobacterium animalis DN 173010 (Danone®) and Lactobacillus casei Shirota (Yakult®) were evaluated on immunomodulation ability and interference of EAEC 042, 1500, H92/3 and I49 strains adhesion in Caco-2 cells, under co-cultivation experiments. Caco-2 cells were submitted EAEC strains infection in presence and absence of both probiotics, separately and together. The EAEC strains substantially increased IL-8 production by infected Caco-2 cells, whereas it not occurs with other cytokines. In synergistic condition, probiotic strains proved to be able to modulate pro-inflammatory cytokines IL-1β, IL-6, IL-10 and TNF-α production of Caco-2 cells infected by EAEC. However, probiotic strains did not modulate IL-8 production. Increased TNF-α production by both infected and non-EAEC infected cells was induced by probiotics. Probiotics reestablished the anti-inflammatory cytokine IL-10 production in EAEC infection. EAEC strains showed diverse Caco-2 cell quantitative adherence numbers when co-cultivated with probiotics, which adhesion increased or decreased on differentiated and non-differentiated Caco-2 cells. Probiotic strains adhere similarly on differentiated and non-differentiated Caco-2 cells. These results suggest that probiotics presence may interfere in different ways on infection by distinct EAEC strains. This study helps to clarify the role that probiotic bacterial strains activity plays in EAEC infection.