Effect of Saccharomyces cerevisiae var. Boulardii and β-galactomannan oligosaccharide on porcine intestinal epithelial and dendritic cells challenged in vitro with Escherichia coli F4 (K88)

The infection by enterotoxigenic Escherichia coli (ETEC) is one on the most important causes of neonatal and post-weaning diarrhea (PWD) in piglets. ETEC causes significant morbidity and mortality, resulting in a large economic loses in the porcine industry. One of the most common ETEC in swine is serotype 0149 which carries the K88 (F4) adhesin that enables the attachment of the bacteria to the intestinal epithelium. ETEC colonizes ileum [1,2], penetrate the epithelium and its pathogenesis is ascribed to the production of different combination of heat-labile (LT) and heat-stable (ST) enterotoxins [3,4].Antibiotic growth promoters (AGPs) have been long used in animal feeding to prevent neonatal and PWD in piglets. The use of AGPs increases the prevalence of bacteria resistant to antibiotics in farm animals and constitutes a potential risk of antibiotic resistance transference to human pathogenic bacteria, following to consumption of animal derived products [5]. The European ban of AGPs in animal production (EC 1831/2003) increased the need to develop new alternatives [6] to control and prevent animal colonization by pathogenic bacteria and somehow guarantee animal welfare and food safety.Probiotics and prebiotics are interesting alternatives to AGP for animal feeding. They are believed to control pathogenic bacteria colonization and to enhance the mucosal immune system, resulting in a decreased pathogenic load and improving animal welfare [7]. The yeast Saccharomyces cerevisiae var. Boulardii (Scb) is a well-known probiotic with proven effects for the treatment and prevention of gastrointestinal diseases (see [8] for review). Typically, between 30-60% of Saccharomyces yeast wall is composed by polysaccharides [9] and specifically mannose and galactose mannans represent respectively more than 50 μg/mg of yeast dry mass [10]. Our center (Institut de Recerca i Tecnologia Agroalimentàries, IRTA) developed a highly rich β-galactomannan prebiotic (βGM) from the carob bean