Selenium Source Impacts Protection of Porcine Jejunal Epithelial Cells from Cadmium-Induced DNA Damage, with Maximum Protection Exhibited with Yeast-Derived Selenium Compounds

Selenium (Se) is found in inorganic and organic forms, both of which are commonly used in animal feed supplements. The aim of this study was to determine the impact of the chemical form of Se on its associated ameliorative effects on cadmium (Cd)-induced DNA damage in a porcine model. At a cellular level, Cd mediates free oxygen radical production leading in particular to DNA damage, with consequential mutagenesis and inhibition of DNA replication. In this study, porcine jejunal epithelial cells (IPEC-J2) were pre-incubated for 48 h with one of Se-yeast (Sel-Plex), selenomethionine (Se-M), sodium selenite (Se-Ni) or sodium selenate (Se-Na). The effects of this supplementation on cell viability and DNA damage following cadmium chloride (CdCl2) exposure were subsequently evaluated. IPEC-J2 cells were cultivated throughout in medium supplemented with porcine serum to generate a superior model that recapitulated the porcine gut epithelium. The results illustrated that Se antioxidant effects were both composition- and dose-dependent as evident from cell viability (Alamar Blue and 5-carboxyfluorescein diacetate acetoxymethyl ester) and DNA damage assays (Comet and TUNEL). Both the Se-yeast and Se-M organic species, when used at the European Food Safety Authority guideline levels, had a protective effect against Cd-induced DNA damage in the IPEC-J2 model system whereas for inorganic Se-Ni and Se-Na sources no protective effects were observed and in fact these were shown to enhance the negative effects of Cd-induced DNA damage. It can be concluded that nutritional supplementation with organoselenium may protect porcine gut integrity from damage induced by Cd.