Effect of Pre-Exposure to Deoxynivalenol on the Response of Porcine Intestinal Epithelial Cells to F18 E. coli Infection

The mycotoxin deoxynivalenol (DON) is a common contaminant found in swine diets, causing decreased growth performance and poor health. Additionally, F18 enterotoxigenic <i>E. coli</i> is a leading cause of post-weaning diarrhea. Nursery pigs are often exposed to each of them after weaning; however, it is unknown what impact the combination of these stressors has on gastrointestinal health. Therefore, the objective of this study was to investigate the effect of pre-exposure to DON on the response of intestinal porcine epithelial cells (IPEC-J2) to challenge with enterotoxigenic F18 <i>E. coli</i>. Four groups were compared: Control (untreated cells), DON (cells treated with 0.5 μM DON for 24 h), F18 <i>E. coli</i> (multiplicity of infection 5:1, varied duration) and DON + <i>E. coli</i> (DON treatment with subsequent <i>E. coli</i> infection). Gene expression of IL-8, IL-6 and TNFα was significantly increased in cells infected with <i>E. coli</i> for 3 h vs. uninfected cells (<i>p</i> < 0.0001, <i>p</i> < 0.0001 and <i>p</i> < 0.0001, respectively). There was an interactive effect between DON and <i>E. coli</i> on IL-8 gene expression; cells pretreated with DON before <i>E. coli</i> infection had a higher expression of IL-8 than those not pretreated (<i>p</i> < 0.05). The concentration of IL-8 protein was significantly increased by <i>E. coli</i> (<i>p</i> < 0.0001). Claudin 1 and Occludin protein abundance were reduced by <i>E. coli</i> as measured by Western blot. Cytotoxicity was increased by <i>E. coli</i> vs. Control (<i>p</i> < 0.05). Pretreatment with DON increased the amount of <i>E. coli</i> that adhered to IPEC-J2 cells (<i>p</i> < 0.01) 30 min post-infection. FITC-dextran passage was increased in the DON + <i>E. coli</i> treatment vs. <i>E. coli</i> alone (<i>p</i> < 0.0001). Transepithelial electrical resistance (TEER) was decreased by DON when compared to untreated cells at 0 h (<i>p</i> < 0.0001). Similarly, DON + <i>E. coli</i> exhibited lower TEER vs. <i>E. coli</i> alone at 2 h post-infection (<i>p</i> < 0.0001). Taken together, these results indicate that DON pre-exposure increased the severity of <i>E. coli</i> infection on endpoints such as barrier permeability and <i>E. coli</i> adhesion.