Investigating small intestine’s permeability via TEER and tight junction expression

Abstract

The use of hiyper-prolific sows is a common practice in the swine industry. Improving larger sized litters enhance the presence of low birth weight piglets (LBW< 0.8 kg) which are more likely to die. The transition to weaning is a stressful event compromising the gut homeostasis, growth and survival rates, especially on LBW piglets. Currently, the early-weaning is a strategy performed consisting in the weaning time anticipation to 2- 3 weeks of age. In addition with the high mortality and morbidity rates the swine production is hampered resulting in economic losses. The effect of the birth weight (BW), weaning strategy (WS) and the small intestine area (SIA) were studied in newborn piglets on the pre-weaning phase by the expression of zonula occludens-1 (ZO-1). 72 pairs of Hypor sex-matched littermates catalogued as low birth weight (LBW< 1 kg, n=36) or normal birth weight (NWB, n=36) were randomly distributed to the rearing systems from 3 days to 3 weeks of age. The early-weaned (EW) piglets were artificially fed in brooders with a milk-replacer provided ad libitum. On conventional weaning (CW), piglets stayed with sow and intake colostrum. Pairs of LBW-NBW were slaughtered at 3, 5, 8 and 19 days old. Tissue samples from duodenum (5%) and ileum (75%) were harvested to quantify the ZO-1 expression. Any significant differences related to BW and WS were found although colostrum exerted a greater effect the ileum and in LBW piglets. Relevant differences were observed within time (p= 0.001) and ileum (p=0.0005), improving the expression in 5-19 (p<0.001) and 8-19 (p=0.007) days. In parallel, in vitro experiments on IPEC-J2 cell monolayers tested the permeability (FITC-Dextran, FD4), the trans-epithelial electrical resistance (TEER) and the immunolocalization of ZO-1 after 1 mM H2o2, 4 mM DEM and ethoxyquin treatments. The effect of 1 mM H2o2 affect the permeability (p =2.73•10-5) while time and time: stressor (p< 2•10-16) influenced TEER values. The 4 mM DEM incubation showed significant differences within time and stressor (p<2•10-16), ethoxyquin (p=0.00041) and DEM:ethoxyquin (p=1.11•10-5). In conclusion, the IPEC-J2 cell line is a reliable model to screen the antioxidant potential reducing the animal experimentation. Moreover, the permeability and TEER evaluate the damage of the intestinal barrier due to the dependent doses-effect between the ethoxyquin and oxidant