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Abstract：
Porphyromonas gingivalis (Pg), a Gram-negative oral pathogen, promotes and accelerates periodontitis-associated gut disorders. Intestinal epithelial barrier dysfunction is crucial in the pathogenesis of intestinal and systemic diseases. In this study, we sought to elucidate the protective role of cinnamaldehyde (CNM, an activator of Nrf2) against P. gingivalis (W83) and Pg-derived lipopolysaccharide (Pg-LPS) induced intestinal epithelial barrier dysfunction via antioxidative mechanisms in IEC-6 cells. IEC-6 (ATCC, CRL-1592) cells were pretreated with or without CNM (100 µM), in the presence or absence of P. gingivalis (strain W83, 109 MOI) or Pg-LPS (1, 10, and 100 µg/mL), respectively, between 0-72 h time points by adopting a co-culture method. Intestinal barrier function, cytokine secretion, and intestinal oxidative stress protein markers were analyzed. P. gingivalis or Pg-LPS significantly (p < 0.05) increased reactive oxygen species (ROS) and malondialdehyde (MDA) levels expressing oxidative stress damage. Pg-LPS, as well as Pg alone, induces inflammatory cytokines via TLR-4 signaling. Furthermore, infection reduced Nrf2 and NAD(P)H quinone dehydrogenase 1 (NQO1). Interestingly, inducible nitric oxide synthase (iNOS) protein expression significantly (p < 0.05) increased with Pg-LPS or Pg infection, with elevated levels of nitric oxide (NO). CNM treatment suppressed both Pg- and Pg-LPS-induced intestinal oxidative stress damage by reducing ROS, MDA, and NO production. Furthermore, CNM treatment significantly upregulated the expression of tight junction proteins via increasing the phosphorylation levels of PI3K/Akt/Nrf2 suppressing inflammatory cytokines. CNM protected against Pg infection-induced intestinal epithelial barrier dysfunction by activating the PI3K/Akt-mediated Nrf2 signaling pathway in IEC-6 cells.
摘要：
牙龈卟啉单胞菌（Pg），革兰氏阴性口腔病原体，促进和加速牙周炎相关的肠道疾病。肠上皮屏障功能障碍在肠道和全身性疾病的发病机制中至关重要。在这项研究中,我们试图阐明肉桂醛的保护作用(CNM，Nrf2）针对牙龈卟啉单胞菌（W83）的激活剂和Pg衍生的脂多糖（Pg-LPS）通过IEC-6细胞中的抗氧化机制诱导的肠上皮屏障功能障碍。IEC-6(ATCC,CRL-1592)细胞用或不用CNM(100μM)预处理，在存在或不存在牙龈卟啉单胞菌（菌株W83，109MOI）或Pg-LPS（1、10和100µg/mL）的情况下，分别,通过采用共培养方法在0-72小时时间点之间。肠屏障功能，细胞因子分泌，和肠道氧化应激蛋白标志物进行分析。牙龈卟啉单胞菌或Pg-LPS显著(p<0.05)增长活性氧(ROS)和丙二醛(MDA)表达氧化应激毁伤的程度。Pg-LPS,以及单独的PG，通过TLR-4信号诱导炎症细胞因子。此外，感染减少Nrf2和NAD（P）H醌脱氢酶1（NQO1）。有趣的是,诱导型一氧化氮合酶(iNOS)蛋白表达随着Pg-LPS或Pg感染而显著增加(p<0.05),一氧化氮（NO）水平升高。CNM治疗通过减少ROS抑制Pg-和Pg-LPS诱导的肠道氧化应激损伤,MDA,没有生产。此外，CNM治疗通过增加PI3K/Akt/Nrf2抑制炎性细胞因子的磷酸化水平显著上调紧密连接蛋白的表达。CNM通过激活IEC-6细胞中PI3K/Akt介导的Nrf2信号通路来保护免受Pg感染诱导的肠上皮屏障功能障碍。
