Toxicity Of Fumartoxin B1 On Porcine Intestinal Epithelial Cells

Fumonisin is a secondary metabolite produced by Fusarium moniliforme,Fusarium rotundus and so on.It pollutes corn,wheat,sorghum,rice and other food crops around the world.It can cause human esophageal cancer and equine leukomalacia syndrome.Pulmonary edema in pigs,liver and kidney damage in rodents,etc.Among them,fumonisin B1（FB₁）has the strongest toxicity,the most extensive pollution,and is the most studied type at present.The purpose of this study was to investigate the effect of FB₁ on the barrier function and autophagy of porcine intestinal epithelial cells（IPEC-J2）,and to lay a theoretical foundation for the study of its pathogenic mechanism.In this study,IPEC-J2 cells were cultured in vitro to study the mechanism of cytotoxicity of different concentrations of FB₁ to IPEC-J2 cells.The effects of FB₁ on the viability of IPEC-J2 cells exposed to FB₁ for 24 h and 48 h were detected by MTT assay.The results showed that 10-50μg/mL FB₁ for 24 h had no significant effect on the cell viability.However,the survival rate of cells exposed to 25μg/mL and 50μg/mL FB₁ for 48h was significantly decreased.In this study,the effects of FB₁ on tight junctions,mucin and paracellular permeability of IPEC-J2 cells were studied in order to investigate the effect of FB₁ on the barrier function of porcine small intestine epithelial cells.Results the expression of tight junction protein Claudin-1,including,ZO-1 mRNA and protein were significantly decreased in FB₁ cells exposed to 50μg/mL for 48 h.10μg/mL FB₁ inhibited the expression of MUC1 mRNA in IPEC-J2 cells,while 25μg/mL and 50μg/mL FB₁ promoted the relative expression of MUC2 mRNA.FB₁ at 50μg/mL for 24 h and 48 h significantly increased the paracellular permeability of cell membrane.The results indicated that FB₁ induced the damage of IPEC-J2 cell barrier function.The effects of FB₁ on autophagy in porcine intestinal epithelial cells were studied.The results showed that 50μg/mL FB₁ significantly decreased the expression of LC3-II/I mRNA and protein,as well as the relative expression of autophagy-related genes Beclin 1,p62,ATG 5 and ATG7 mRNA.This indicated that FB₁ inhibited autophagy of IPEC-J2 cells.At the same time,the AKT/mTOR,AMPK/mTOR signaling pathway of autophagy was detected,and it was found that FB₁ could inhibit autophagy by activating AMPK/mTOR signaling pathway.Rapamycin was used as autophagy inducer to study the relationship between cell barrier function and autophagy.Results 75 pM Rapamycin significantly inhibited the increase of cell paracellular permeability induced by 50μg/mL FB₁,suggesting that Rapamycin has protective effect on FB₁-induced damage of cell barrier function.FB₁ may induce intestinal epithelial barrier damage by inhibiting autophagy.