In recent years the use of low-dose dietary antibiotics has been banned in the context of growth promotion of livestock, because of the antibiotic resistance of some pathogenic bacteria. For this reason nowadays there is a growing interest to replace the use of various antibiotics by different natural alternatives, such as probiotics. Probiotics are defined as live microbial food/feed ingredients that have a beneficial effect on the host health and well-being. Probiotics have proven effects in the prevention and/or treatment of several intestinal infections, disorders and diseases but the underlying mechanisms remain to be elucidated.
In this study the role of certain probiotic bacterial strains and their metabolic products will be investigated in the prevention of LPS (lipopolysaccharide)- induced (sub)cellular changes. To monitor the complex interaction among host epithelium, inflammatory stimuli and protective agents, IPEC-J2 cell line derived from porcine jejunal epithelium will be used as model system. IL-6, IL-8, TNF-α expression will be measured at the level of transcription (determination of mRNA by real-time PCR) and translation (protein assay by ELISA). The effects of LPS treatment on IPEC-J2 monolayer integrity will be followed by measurement of transepithelial electrical resistance and via fluorometric detection of FITC-dextran 4kDa paracellular marker. The protective agent(s) – bacteria or metabolites – will be determined and attempts will be made to purify and identify the active compound(s) present among the metabolic products. The in vitro observations will be tested in in vivo animal models (rodents and/or swine).