N-Acetyl-D-galactosamine prevents soya bean agglutinin-induced intestinal barrier dysfunction in intestinal porcine epithelial cells

Soya bean agglutinin (SBA) is a glycoprotein and the main anti-nutritional component in most soya bean feedstuffs. It is mainly a non-fibre carbohydrate-based protein and represents about 10% of soya bean-based anti-nutritional effects. In this study, we sought to determine the effects of N-Acetyl-D-galactosamine (GalNAc or D-GalNAc) on the damage induced by SBA on the membrane permeability and tight junction proteins of piglet intestinal epithelium (IPEC-J2) cells. The IPEC-J2 cells were pre-cultured with 0, 0.125 x 10(-4), 0.25 x 10(-4), 0.5 x 10(-4), 1.0 x 10(-4) and 2.0 x 10(-4) mmol/L GalNAc at different time period (1, 2, 4 and 8 hr) before being exposed to 0.5 mg/ml SBA for 24 hr. The results indicate that pre-incubation with GalNAc mitigates the mechanical barrier injury as reflected by a significant increase in trans-epithelial electric resistance (TEER) value and a decrease in alkaline phosphatase (ALP) activity in cell culture medium pre-treated with GalNAc before incubation with SBA as both indicate a reduction in cellular membrane permeability. In addition, mRNA levels of the tight junction proteins occludin and claudin-3 were lower in the SBA-treated groups without pre-treatment with GalNAc. The mRNA expression of occludin was reduced by 17.3% and claudin-3 by 42% (p < 0.01). Moreover, the corresponding protein expression levels were lowered by 17.8% and 43.5% (p < 0.05) respectively. However, in the GalNAc pre-treated groups, occludin and claudin-3 mRNAs were reduced by 1.6% (p > 0.05) and 2.7% (p < 0.01), respectively, while the corresponding proteins were reduced by 4.3% and 7.2% (p < 0.05). In conclusion, GalNAc may prevent the effect of SBA on membrane permeability and tight junction proteins on IPEC-J2s.