Jiangxi Province Key Laboratory of Animal Nutrition, Jiangxi Province Key Innovation Center of Integration in Production and Education for High-quality and Safe Livestock and Poultry, Jiangxi Agricultural University, Nanchang, China.
Gannan Academy of Sciences, Ganzhou, China.
J Anim Physiol Anim Nutr (Berl). 2021 Nov;105(6):1063-1074. doi: 10.1111/jpn.13540. Epub 2021 Apr 5.
This study aimed to investigate the protective effects and underlying mechanism of seaweed polysaccharide (SWP) on intestinal epithelial barrier dysfunction induced by E. coli in an IPEC-J2 model. A preliminary study was done to screen optimum SWP concentrations by cell viability, cytotoxicity, apoptosis and proliferation evaluation. The regular study was conducted to evaluate the protective effects of SWP against E. coli challenge via the analysis of transepithelial electrical resistance (TEER), tight junction proteins, NF-κB signalling pathway, proinflammatory cytokines and the E. coli adhesion and invasion. Our results show that 4 h E. coli challenge down-regulated tight junction proteins expression, decreased TEER, activated NF-κB signalling pathway and increased proinflammatory response, which indicates that the E. coli infection model was well-established. Pre-treatment with 240 μg/ml SWP for 24 h alleviated the 4 h E. coli -induced intestinal epithelial barrier dysfunction, as evidenced by the up-regulated expression of Occludin, Claudin-1 and ZO-1 at both mRNA and protein level and the increased TEER of IPEC-J2 cells. Pre-incubation with 240 μg/ml SWP for 24 h inhibited the activation of the NF-κB signalling pathway by 4 h E. coli challenge, including the decreased mRNA expression of TLR-4, MyD88, IκBα, p-65, as well as the reduced ratio of protein expression of p-p65/p65. Also, pre-treatment with 240 μg/ml SWP for 24 h decreased proinflammatory response (IL-6 and TNF-α) induced by 4 h E. coli challenge and decreased the E. coli adhesion and invasion. In conclusion, SWP mitigated intestinal barrier dysfunction caused by E. coli through NF-κB pathway in IPEC-J2 cells and 240 μg/ml SWP exhibited better effect. Our results also provide a fundamental basis for SWP in reducing post-weaning diarrhoea of weaned piglets, especially under E. coli -infected or in-feed antibiotic-free conditions.
本研究旨在探讨海藻多糖 (SWP) 对大肠杆菌诱导的肠上皮屏障功能障碍的保护作用及其潜在机制，在 IPEC-J2 模型中。通过细胞活力、细胞毒性、细胞凋亡和增殖评估进行了初步研究，以筛选最佳 SWP 浓度。进行了常规研究，通过分析跨上皮电阻 (TEER)、紧密连接蛋白、NF-κB 信号通路、促炎细胞因子以及大肠杆菌的粘附和侵袭，评估 SWP 对大肠杆菌攻击的保护作用。我们的结果表明，4 小时大肠杆菌攻击下调紧密连接蛋白的表达，降低 TEER，激活 NF-κB 信号通路并增加促炎反应，表明大肠杆菌感染模型建立良好。240μg/ml SWP 预处理 24 小时可缓解 4 小时大肠杆菌诱导的肠上皮屏障功能障碍，这表现在 IPEC-J2 细胞中 Occludin、Claudin-1 和 ZO-1 的 mRNA 和蛋白水平表达上调，TEER 增加。240μg/ml SWP 预孵育 24 小时可抑制 4 小时大肠杆菌攻击引起的 NF-κB 信号通路的激活，包括 TLR-4、MyD88、IκBα、p-65 的 mRNA 表达减少，以及 p-p65/p65 蛋白表达比值降低。此外，240μg/ml SWP 预处理 24 小时可降低 4 小时大肠杆菌攻击引起的促炎反应 (IL-6 和 TNF-α)，并减少大肠杆菌的粘附和侵袭。总之，SWP 通过 IPEC-J2 细胞中的 NF-κB 通路减轻大肠杆菌引起的肠屏障功能障碍，240μg/ml SWP 表现出更好的效果。我们的研究结果还为 SWP 在减少断奶仔猪断奶后腹泻，特别是在大肠杆菌感染或无抗生素饲料条件下提供了基础。
