Enterotoxigenic Escherichia coli (ETEC) K88 commonly colonize in the small intestine and keep releasing enterotoxins to impair the intestinal barrier function and trigger inflammatory reaction. Although Lactobacillus salivarius (L. salivarius) has been reported to enhance intestinal health, it remains to be seen whether there is a functional role of L. salivarius in intestinal inflammatory response in intestinal porcine epithelial cell line (IPEC-J2) when stimulated with ETEC K88. In the present study, IPEC-J2 cells were first treated with L. salivarius followed by the stimulation of ETEC K88 for distinct time period. ETEC K88 adherent status, pattern recognition receptors (PRRs) mRNA, mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) activation, the release of pro-inflammation cytokines and cell integrity were examined. Aside from an inhibited adhesion of ETEC K88 to IPEC-J2 cells, L. salivarius was capable of remarkably attenuating the expression levels of interleukin (IL)-1β, tumor necrosis factor-α (TNF-α), IL-8, Toll-like receptor (TLR) 4, nucleotide-binding oligomerization domain (NOD)-like receptor pyrin domain-containing protein (NLRP) 3 and NLRP6. This alternation was accompanied by a significantly decreased phosphorylation of p38 MAPK and p65 NF-κB during ETEC K88 infection with L. salivarius pretreatment. Western blot analysis revealed that L. salivarius increased the expression levels of zona occludens 1 (ZO-1) and occludin (P < 0.05) in ETEC K88-infected IPEC-J2 cells. Compared with ETEC K88-infected groups, the addition of L. salivarius as well as extra inhibitors for MAPKs and NF-κB to ETEC K88-infected IPEC-J2 cells had the capability to reduce pro-inflammatory cytokines. Collectively, our results suggest that L. salivarius might reduce inflammation-related cytokines through attenuating phosphorylation of p38 MAPK and blocking the NF-κB signaling pathways. Besides, L. salivarius displayed a potency in the enhancement of IPEC-J2 cell integrity.

中文翻译：

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唾液乳杆菌通过 ETEC K88 诱导的 IPEC-J2 细胞中的 NF-κB 信号传导减轻炎症。

产肠毒素大肠埃希菌 (ETEC) K88 通常在小肠定殖并不断释放肠毒素，从而损害肠道屏障功能并引发炎症反应。尽管据报道唾液乳杆菌 (L. salivarius) 可增强肠道健康，但当用 ETEC 刺激时，唾液乳杆菌是否在猪肠上皮细胞系 (IPEC-J2) 的肠道炎症反应中发挥功能性作用仍有待观察K88。在本研究中，IPEC-J2 细胞首先用 L. salivarius 处理，然后在不同时间段内刺激 ETEC K88。检查了 ETEC K88 贴壁状态、模式识别受体 (PRR) mRNA、丝裂原活化蛋白激酶 (MAPK) 和核因子-κB (NF-κB) 激活、促炎细胞因子的释放和细胞完整性。除了抑制 ETEC K88 与 IPEC-J2 细胞的粘附外，唾液乳杆菌还能够显着降低白细胞介素 (IL)-1β、肿瘤坏死因子-α (TNF-α)、IL-8、Toll-的表达水平。样受体 (TLR) 4、核苷酸结合寡聚化结构域 (NOD) 样受体含吡啶结构域蛋白 (NLRP) 3 和 NLRP6。在用唾液乳杆菌预处理的 ETEC K88 感染期间，这种交替伴随着 p38 MAPK 和 p65 NF-κB 的磷酸化显着降低。蛋白质印迹分析显示 L. salivarius 增加了 ETEC K88 感染的 IPEC-J2 细胞中 zona occludens 1 (ZO-1) 和 occludin (P < 0.05) 的表达水平。与 ETEC K88 感染组相比，添加 L. 唾液以及针对 ETEC K88 感染的 IPEC-J2 细胞的 MAPK 和 NF-κB 的额外抑制剂具有减少促炎细胞因子的能力。总的来说，我们的结果表明 L. salivarius 可能通过减弱 p38 MAPK 的磷酸化和阻断 NF-κB 信号通路来减少炎症相关的细胞因子。此外，L. salivarius 在增强 IPEC-J2 细胞完整性方面表现出效力。