TNF and fetal growth restriction: Furthermore, the mRNA expression of zonula occludens (ZO)-1 at 7 days of age, ZO-1, occludin, and interleukin (IL)-4 at 21 days of age were down-regulated in the IUGR piglets, whereas tumor necrosis factor (TNF)-α and nuclear factor-kappa B (NF-κB) at 28 days of age were up-regulated, when compared with the NBW piglets (p < 0.05).