Deoxynivalenol impairs porcine intestinal barrier function and decreases the protein expression of claudin-4 through a mitogen-activated protein kinase-dependent mechanism.

Deoxynivalenol (DON) is a common mycotoxin that contaminates cereals and their by-products. The gastrointestinal tract is the first physical barrier against ingested food contaminants. DON contributes to the loss of barrier function of the intestine through the decreased expression of claudin-4 protein, a tight junction protein. The mechanism by which DON alters the intestinal barrier function remains poorly characterized. Therefore, we investigated the involvement of mitogen-activated protein kinases (MAPK) in the DON-induced loss of barrier function. We first verified that 30 μmol/L of DON activated MAPK in a highly sensitive porcine intestinal epithelial cell line (IPEC-1). Inhibition of p44/42 extracellular signal-regulated kinase (ERK) phosphorylation, with 0.5 μmol/L of the specific MAPK pharmacological inhibitor U0126 for 2 h, restored the barrier function of the differentiated intestinal epithelial cell monolayers. The restoration of barrier function was evaluated by trans-epithelial electrical resistance measurements and tracer flux paracellular permeability experiments. The U0126 also restored the intestinal expression of claudin-4 protein, thereby demonstrating that MAPK activation is involved in claudin-4 protein expression and claudin-4 is involved in the maintenance of the intestinal epithelial cell barrier function. Further experiments indicated that p44/42 ERK is not involved in the transcriptional regulation of claudin-4. In conclusion, we demonstrated that DON-induced activation of the p44/42 ERK signaling pathway inhibits the expression of claudin-4 protein, which leads to impaired intestinal barrier function. Given the high levels of DON in cereal grains, these observations of impaired barrier function have implications for human and animal health.