PSVI-18 - Mycotoxin exposure and its impact on inflammatory response and growth in pigs and intestinal epithelial cells

Abstract: The objective of these studies was to determine the effect of pre-exposure to the mycotoxin deoxynivalenol (DON) on the response of intestinal porcine epithelial cells (IPEC-J2) and nursery pigs to immune challenge with F18 E. coli and lipopolysaccharide (LPS), respectively. In-vitro experiments involved four experimental treatments: Control, DON (0.5μM, 24hr), F18 E. coli (multiplicity of infection 5:1, 3hr) and DON + E. coli. Results showed that IL-8, IL-6 and TNFα gene expression were upregulated in the E. coli and DON + E. coli treatments (P< 0.05). Relative to the Control, Claudin-4 protein expression tended to be decreased in the E. coli treatment (P=0.054) and was significantly reduced in the DON + E. coli treatment (P=0.015). Furthermore, Occludin protein expression was downregulated in E. coli (P=0.001) and DON + E. coli (P=0.001) treatments relative to Control. In each case, the DON treatment was not different from Control. A lactate-dehydrogenase assay was completed to evaluate cell death. This assay revealed that the E. coli treatment increased cell death relative to Control and DON treatments (P< 0.05). Additionally, the DON + E. coli treatment had higher cell death relative to the Control, DON and E. coli treatments (P< 0.05), indicating that pre-exposure to DON increased the lethality of E. coli in IPEC-J2 cells. To complement in-vitro work, a 28-day nursery study was conducted using 128 piglets allotted to 4 treatments with each treatment having a total of eight replicates in a randomized-complete block design. The treatments were: Control (fed standard diets, no final LPS injection), Mycotoxin (fed diets formulated to contain 2.5 ppm DON, no final LPS injection), Control + LPS (fed control diets, injected with LPS at 25 μg/kg BW on d 28), and Mycotoxin + LPS (fed mycotoxin contaminated diets, injected with LPS at 25 μg/kg BW on d 28). Body weights (kg) were higher (P < 0.05) in the Control than Mycotoxin pigs on d 14 (9.6 vs. 9.3) and d 28 (17.1 vs. 15.8). Similarly, average daily gain was higher (P < 0.05) in the Control than Mycotoxin pigs from d 1-14, 15-28 and overall (1-28). However, Gain:Feed was not affected by treatments (P > 0.05). Rectal temperatures were collected from pigs hourly for four hours following injection. At 1, 3 and 4 hours post-injection, pigs injected with LPS had elevated temperatures compared to those injected with saline (P=0.03, P=0.01, and P=0.00, respectively). At 4 hours post-injection, the Mycotoxin + LPS injection treatment tended (P=0.09) to have a higher rectal temperature relative to control diet + LPS injection treatment. In sum, prior mycotoxin exposure may impact how intestinal cells and nursery pigs respond to inflammatory or immune challenge with a potential consequence on intestinal function and growth of pigs.