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 E. coli 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 E. coli. Four groups were compared: Control (untreated cells), DON (cells treated with 0.5 μM DON for 24 h), F18 E. coli (multiplicity of infection 5:1, varied duration) and DON + E. coli (DON treatment with subsequent E. coli infection). Gene expression of IL-8, IL-6 and TNFα was significantly increased in cells infected with E. coli for 3 h vs. uninfected cells (p < 0.0001, p < 0.0001 and p < 0.0001, respectively). There was an interactive effect between DON and E. coli on IL-8 gene expression; cells pretreated with DON before E. coli infection had a higher expression of IL-8 than those not pretreated (p < 0.05). The concentration of IL-8 protein was significantly increased by E. coli (p < 0.0001). Claudin 1 and Occludin protein abundance were reduced by E. coli as measured by Western blot. Cytotoxicity was increased by E. coli vs. Control (p < 0.05). Pretreatment with DON increased the amount of E. coli that adhered to IPEC-J2 cells (p < 0.01) 30 min post-infection. FITC-dextran passage was increased in the DON + E. coli treatment vs. E. coli alone (p < 0.0001). Transepithelial electrical resistance (TEER) was decreased by DON when compared to untreated cells at 0 h (p < 0.0001). Similarly, DON + E. coli exhibited lower TEER vs. E. coli alone at 2 h post-infection (p < 0.0001). Taken together, these results indicate that DON pre-exposure increased the severity of E. coli infection on endpoints such as barrier permeability and E. coli adhesion.