TDK conference 2019

Since 2006 the usage of antibiotics for prophylaxis and growth promotion in livestock has been banned in the European Union. Therefore, the usage of numerous alternative growth promoter agents has become widespread, including application of probiotics. Beneficial effects of probiotics have been proven in the supportive treatment of various gastrointestinal diseases. Probiotics have numerous positive effects; they strengthen the intestinal barrier, produce numerous metabolites with positive effects, influence the inflammatory response and regulate the expression of cytokines and ROS. The exact mechanisms of action of probiotics is still unknown, thus in order to enhance the knowledge about the molecular basics, it is essential to perform well-controlled in vitro experiments.

The aim of our study was to examine the protective effect of three different bacterial strains against lipopolysaccharide (Salmonella enterica ser. Typhimurium, Escherichia coli O111:B4 and E. coli O127:B8) induced inflammation and oxidative stress in porcine intestinal epithelial cells. In our study, we used IPEC-J2 cell line, originating from the jejunum of new-born unsuckled piglets. The IPEC-J2 cell line is neither transformed nor tumorigenic, therefore it is a good model of porcine small intestine. The examined probiotic strains were Lactobacillus plantarum, Lactobacillus rhamnosus and Enterococcus faecium. In the experiment we investigated the beneficial effects of the supernatant produced by the above mentioned bacteria. The intracellular redox state was measured with DCFH-DA, while the extracellular H2O2 level was determined with Amplex Red method. As a marker of inflammatory response, we measured the IL-6 level with sandwich ELISA method.

According our results, metabolites of Lactobacillus plantarum and Enterococcus faecium prevented LPS-induced IL-6 production. The intracellular redox state was increased after the treatments of different LPS strains, which could only be decreased with the supernatant of Lactobacillus rhamnosus. The extracellular H2O2 level did not show alteration after LPS treatment compared to the control group. In contrast, cell-free supernatants of probiotic strains had significant increasing effect on the extracellular H2O2 level.

We suggest that further studies are necessary to investigate the precise mechanisms of these probiotic bacterial strains.