Institute of Animal Science, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China.
State Key Laboratory of Livestock and Poultry Breeding, Guangzhou 510640, China.
Int J Mol Sci. 2017 Nov 13;18(11):2409. doi: 10.3390/ijms18112409.
Interleukin (IL)-22-producing Natural Killer (NK) cells protect the gut epithelial cell barrier from pathogens. A strain of probiotics, Lactobacillus plantarum (L. plantarum, LP), was previously found by our laboratory to significantly improve the mucosal barrier integrity and function of the small intestine in pigs. However, it was unclear whether LP benefited the intestinal mucosal barrier via interactions with the intestinal NK cells. The present study, therefore, was focused on the therapeutic effect of NK cells that were stimulated by LP on attenuating enterotoxigenic Escherichia coli (ETEC)-induced the damage to the integrity of the epithelial cell barrier. The results showed that LP can efficiently increase protein levels of the natural cytotoxicity receptor (NCR) family, and the expression levels of IL-22 mRNA and protein in NK cells. Transfer of NK cells stimulated by LP conferred protection against ETEC K88-induced intestinal epithelial barrier damage in NCM460 cells. We found that NK cells stimulated by LP could partially offset the reduction in NCM460 cell monolayers transepithelial electrical resistance (TEER) caused by ETEC K88, and increase ZO-1 and occludin mRNA and protein expressions by ETEC K88-infected NCM460 cells. Furthermore, adding NK cells that were stimulated by LP to ETEC K88-infected NCM460cells, IL-22R1, p-Stat3, and p-Tyk2 expression by NCM460 cells was increased. Mechanistic experiment showed that NK cells stimulated by LP lost the function of maintaining TEER of NCM460 cells challenged with ETEC K88, when polyclonal anti-IL-22 antibody was used to block IL-22 production. Collectively, our results suggested that LP stimulation of NK could enhance IL-22 production, which might be able to provide defense against ETEC-induced damage to the integrity of intestinal epithelial barrier.
白细胞介素 (IL)-22 产生的自然杀伤 (NK) 细胞保护肠道上皮细胞屏障免受病原体侵害。我们实验室之前发现，一种益生菌植物乳杆菌 (L. plantarum，LP) 可显著提高猪小肠的黏膜屏障完整性和功能。然而，尚不清楚 LP 是否通过与肠道 NK 细胞相互作用来有益于肠道黏膜屏障。因此，本研究集中研究了 LP 刺激的 NK 细胞对减轻肠产毒性大肠杆菌 (ETEC) 诱导的上皮细胞屏障完整性损伤的治疗作用。结果表明，LP 能有效增加 NK 细胞天然细胞毒性受体 (NCR) 家族的蛋白水平，以及 IL-22 mRNA 和蛋白的表达水平。LP 刺激的 NK 细胞转移可防止 ETEC K88 诱导的 NCM460 细胞肠上皮屏障损伤。我们发现，LP 刺激的 NK 细胞可部分抵消 ETEC K88 引起的 NCM460 细胞单层跨上皮电阻 (TEER) 的降低，并增加 ETEC K88 感染的 NCM460 细胞中 ZO-1 和闭合蛋白的 mRNA 和蛋白表达。此外，将 LP 刺激的 NK 细胞添加到 ETEC K88 感染的 NCM460 细胞中，可增加 NCM460 细胞中 IL-22R1、p-Stat3 和 p-Tyk2 的表达。机制实验表明，当使用多克隆抗 IL-22 抗体阻断 IL-22 产生时，LP 刺激的 NK 细胞丧失了维持 ETEC K88 攻击的 NCM460 细胞 TEER 的功能。总之，我们的结果表明，LP 刺激 NK 细胞增强了 IL-22 的产生，这可能能够提供针对 ETEC 引起的肠道上皮屏障完整性损伤的防御。
