Abstract：
Inflammation of the GI tract leads to compromised epithelial barrier integrity, which increases intestine permeability. A compromised intestinal barrier is a critical event that leads to microbe entry and promotes inflammatory responses. Inflammatory bowel diseases that comprise Crohn\'s disease (CD) and ulcerative colitis (UC) show an increase in intestinal permeability. Nerolidol (NED), a naturally occurring sesquiterpene alcohol, has potent anti-inflammatory properties in preclinical models of colon inflammation. In this study, we investigated the effect of NED on MAPKs, NF-κB signaling pathways, and intestine epithelial tight junction physiology using in vivo and in vitro models. The effect of NED on proinflammatory cytokine release and MAPK and NF-κB signaling pathways were evaluated using lipopolysaccharides (LPS)-stimulated RAW 264.7 macrophages. Subsequently, the role of NED on MAPKs, NF-κB signaling, and the intestine tight junction integrity were assessed using DSS-induced colitis and LPS-stimulated Caco-2 cell culture models. Our result indicates that NED pre-treatment significantly inhibited proinflammatory cytokine release, expression of proteins involved in MAP kinase, and NF-κB signaling pathways in LPS-stimulated RAW macrophages and DSS-induced colitis. Furthermore, NED treatment significantly decreased FITC-dextran permeability in DSS-induced colitis. NED treatment enhanced tight junction protein expression (claudin-1, 3, 7, and occludin). Time-dependent increases in transepithelial electrical resistance (TEER) measurements reflect the formation of healthy tight junctions in the Caco-2 monolayer. LPS-stimulated Caco-2 showed a significant decrease in TEER. However, NED pre-treatment significantly prevented the fall in TEER measurements, indicating its protective role. In conclusion, NED significantly decreased MAPK and NF-κB signaling pathways and decreased tight junction permeability by enhancing epithelial tight junction protein expression.
摘要：
胃肠道炎症导致上皮屏障完整性受损，增加肠道通透性。肠屏障受损是导致微生物进入并促进炎症反应的关键事件。包括克罗恩病(CD)和溃疡性结肠炎(UC)的炎症性肠病显示肠通透性增加。Nerolidol(NED),一种天然的倍半萜醇，在结肠炎症的临床前模型中具有有效的抗炎特性。在这项研究中,我们调查了NED对MAPK的影响，NF-κB信号通路,和使用体内和体外模型的肠上皮紧密连接生理学。使用脂多糖（LPS）刺激的RAW264.7巨噬细胞评估NED对促炎细胞因子释放以及MAPK和NF-κB信号通路的影响。随后，NED在MAPK上的作用，NF-κB信号,使用DSS诱导的结肠炎和LPS刺激的Caco-2细胞培养模型评估肠紧密连接的完整性。我们的结果表明，NED预处理显着抑制促炎细胞因子的释放，MAP激酶相关蛋白的表达，和NF-κB信号通路在LPS刺激的RAW巨噬细胞和DSS诱导的结肠炎中的作用。此外，NED治疗显著降低DSS诱导的结肠炎的FITC-葡聚糖通透性。NED处理增强了紧密连接蛋白的表达（claudin-1、3、7和occludin）。跨上皮电阻（TEER）测量值的时间依赖性增加反映了Caco-2单层中健康紧密连接的形成。LPS刺激的Caco-2显示TEER显著降低。然而,NED预处理显著防止了TEER测量值的下降，表明其保护作用。总之,NED通过增强上皮紧密连接蛋白的表达，显著降低MAPK和NF-κB信号通路，降低紧密连接通透性。
