Veterinary session

Intestinal diseases caused by Escherichia coli (E. coli) and Salmonella spp can lead to significant economic losses in food producing animals and can also pose a risk to human health. These pathogens induce oxidative stress in the intestinal tract and impair the function of the intestinal barrier. Taken together, these effects can lead to the development of clinical symptoms or even death.

The pig industry has relied largely on the prophylactic use of antibiotics to combat gastrointestinal diseases and increase production. In response to concerns about antibiotic resistance, the use of antibiotics as growth promoters has been banned in the European Union for almost two decades, and further regulations were introduced in 2022 to control the responsible use of antibiotics in veterinary medicine. The introduction of alternative feed additives to maintain the health of the gastrointestinal tract is important for the pig sector and for human health. Probiotics have been used in veterinary medicine for a long time, but in many cases the exact mechanism of action responsible for their beneficial effects and the extent of their efficacy are not yet fully understood.

In the present study, the protective effect of the probiotic Enterococcus faecium (E. faecium) on IPEC-J2 porcine enteric epithelial cells against pathogenic E. coli and S. enterica ser Typhimurium (S. Typhimurium) was investigated. The Neutral Red assay was used to determine that the viability of IPEC-J2 cells was not affected by E. faecium at concentrations of 10^7 and 10^8 CFU/ml. These concentrations were used in further experiments. To investigate the intracellular redox status of the cells, a DCFH-DA assay was applied, in which E. faecium and pathogenic bacteria were added to the cells using three different treatments (pre-, co-, and post-treatment). The effect of the probiotic strain on the paracellular permeability of the intestinal epithelial cells was tested using the FD4 fluorescent assay.

The results of our study demonstrate that E. faecium significantly reduces the oxidative stress induced by E. coli and S. Typhimurium in porcine intestinal epithelial cells and is also able to attenuate the damage of barrier function. Further in vitro and in vivo studies are needed to elucidate the processes underlying the positive effect of E. faecium.