As the first line of defence against pathogens and endotoxins crossing the intestine-blood barrier, the intestinal epithelial barrier plays a determinant role in pigs' health and growth. 4-Phenylbutyric acid (4-PBA), an aromatic fatty acid, was reported to benefit homeostasis of endoplasmic reticulum and protein synthesis. However, whether 4-PBA affects intestinal epithelial barrier function in pigs is unknown. This study aimed to explore the effects of 4-PBA on the intestinal barrier function, using in vitro models of well-differentiated intestinal porcine epithelial cell (IPEC-J2) monolayers in the transwell plates. Cell monolayers with or without 4-PBA (1.0 mmol/L) treatment were challenged with physical scratch, deoxynivalenol (DON, 2.0 μg/mL, 48 h), and lipopolysaccharide (LPS, 5.0 μg/mL, 48 h), respectively. Transepithelial electrical resistance (TEER) and fluorescein isothiocyanate-dextran (FD-4) permeability were measured to indicate barrier integrity and permeability. Real-time PCR and Western blot were conducted to determine relative gene and protein expressions of tight junction proteins. As expected, physical scratch, DON, and LPS challenges decreased TEER and increased FD-4 permeability. 4-PBA treatment accelerated cell mitigation and rehabilitation of the physical scratch-damaged intestinal epithelial barrier but did not alleviate DON or LPS induced barrier damage. However, once 48-h DON and LPS challenges were removed, rehabilitation of the epithelial barrier function of IPEC-J2 monolayer was accelerated by the 4-PBA treatment. Also, the relative gene and protein expressions of zonula occludens-1 (ZO-1), occludin, and claudin-1 were further upregulated by the 4-PBA treatment during the barrier rehabilitation. Taken together, 4-PBA accelerated the IPEC-J2 cell monolayer barrier recovering from physical scratch, DON-, and LPS-induced damage, via enhancing cell mitigation and expressions of tight junction proteins.

作为抵御病原体和内毒素穿过肠-血屏障的第一道防线，肠上皮屏障对猪的健康和生长起着决定性作用。据报道，4-苯基丁酸 (4-PBA) 是一种芳香族脂肪酸，有助于内质网和蛋白质合成的稳态。然而，4-PBA 是否影响猪的肠上皮屏障功能尚不清楚。本研究旨在利用 Transwell 板中分化良好的猪肠上皮细胞 (IPEC-J2) 单层体外模型，探讨 4-PBA 对肠屏障功能的影响。分别用物理划痕、脱氧雪腐镰刀菌烯醇（DON，2.0 μg/mL，48 小时）和脂多糖（LPS，5.0 μg/mL，48 小时）对有或没有 4-PBA (1.0 mmol/L) 处理的细胞单层进行挑战。测量跨上皮电阻 (TEER) 和异硫氰酸荧光素-葡聚糖 (FD-4) 渗透性以表明屏障完整性和渗透性。进行实时PCR和蛋白质印迹以确定紧密连接蛋白的相对基因和蛋白质表达。正如预期的那样，物理划痕、DON 和 LPS 挑战降低了 TEER 并增加了 FD-4 渗透性。4-PBA 治疗加速了物理划伤损伤的肠上皮屏障的细胞缓解和康复，但没有减轻 DON 或 LPS 诱导的屏障损伤。然而，一旦去除 48 小时 DON 和 LPS 挑战，4-PBA 处理加速了 IPEC-J2 单层上皮屏障功能的恢复。此外，闭锁小带-1 (ZO-1)、occludin、在屏障康复期间，4-PBA 治疗进一步上调了 claudin-1。总之，4-PBA 通过增强细胞缓解和紧密连接蛋白的表达，加速了 IPEC-J2 细胞单层屏障从物理划痕、DON 和 LPS 诱导的损伤中恢复。