Aflatoxin B1 disrupts the intestinal barrier integrity by reducing junction protein and promoting apoptosis in pigs and mice

With the growing diversity and complexity of diet, animals and humans are at risk of exposure to aflatoxin B1 (AFB1), which is a well-known contaminant in the food chain that causes various toxicological effects. The intestine acts as the first barrier against external contaminants, but the effect of AFB1 on intestinal barrier has not been determined. This study aimed to evaluate AFB1 on the intestinal barrier function in vitro and in vivo. In vitro, porcine jejunal epithelial cells (IPEC-J2) were treated with increasing concentrations of AFB1 (10-60 mg/L). In vivo, Kunming (KM) mice were used as controls or gavaged with 1% dimethyl sulfoxide (110 mg/kg b.w.) and AFB1 (0.3 mg/kg b.w.) for 28 days. In IPEC-J2 cells, the cell viability decreased with increasing mycotoxin concentrations, and the viability of IPEC-J2 cells decreased significantly (P < 0.05) when the AFB1 concentrations were greater than 30 mg/L. In addition, quantitative real-time PCR, Western blot analysis, and immunofluorescence results show that AFB1 can downregulate the tight junction proteins and increase the expression levels of Caspase-3 and the ratio of Bax/Bcl-2, suggesting that AFB1 was cytotoxic to IPEC-J2. In vivo, the ratio of villus height to crypt depth, the intestinal wall thickness, the number of intestinal villus per 1000 µm in the jejunum, the expression levels of ZO-1, Claudin-3, Occludin, MUC2, and Caspase-3, and the ratio of Bax/Bcl-2 were significantly affected in mice exposed to AFB1. In vitro and in vivo results showed that the effects of exposure to AFB1 on the intestinal function in the jejunum of KM mice and in the IPEC-J2 was similar, suggesting that AFB1 may adversely affect animal intestine.