Du Lin, Li Jianke, Zhang Xitong, Wang Lifang, Zhang Weimin, Yang Mi, Hou Chen
Department of Food Quality and Safety, College of Food Engineering and Nutritional Science, Shaanxi Normal University, Xi'an, China.
Department of Food Quality and Safety, College of Food & Bioengineering, Henan University of Science and Technology, Luoyang, China.
Food Nutr Res. 2019 Apr 23;63. doi: 10.29219/fnr.v63.3392. eCollection 2019.
Inflammatory response mediated by activated immune cells is a vital process in host defense system while responding to various stresses. Our previous studies have indicated that pomegranate peel polyphenols (PPPs) and their main components punicalagin (PC) and ellagic acid (EA) decreased pro-inflammatory cytokines and inflammatory mediators by regulating the mitogen-activated protein kinases (MAPKs) pathway, but whether these tested polyphenols play an important role in NF-κB signaling pathway, another crucial pathway of inflammation, remains unclear.
In this study, we analyzed the anti-inflammatory effect of these polyphenols via TLR4-NF-κB pathway in lipopolysaccharide (LPS)-induced RAW264.7 macrophages.
Different concentrations of PPPs, PC, and EA were pre-incubated with RAW264.7 macrophages and then stimulated with LPS (1 μg/mL), and the effects of reactive oxygen species and TLR4 were investigated. Moreover, NF-κB p65 nuclear translocation and phosphorylation, and degradation of IκB were measured by Western blot. Furthermore, the influence of pro-inflammatory cytokines was detected by enzyme-linked immunosorbent assay (ELISA).
Our data showed that PPPs, PC, and EA inhibited LPS-induced intracellular ROS production and suppressed the mRNA and protein expression levels of TLR4 in a dose-dependent manner. Moreover, the anti-inflammatory mechanism was involved in blocking LPS-induced phosphorylation, degradation of IκB, and nuclear translocation of p65. Additionally, PPPs and PC exhibited a stronger anti-inflammatory effect than that of EA.
The results indicated that PPPs possess potent anti-inflammatory effect, and PC was the main effective component in PPPs, which provided new insights into the utilization of PPPs to prevent inflammation-associated disorders.
由活化免疫细胞介导的炎症反应是宿主防御系统应对各种应激时的一个重要过程。我们之前的研究表明，石榴皮多酚（PPPs）及其主要成分石榴皮苷（PC）和鞣花酸（EA）通过调节丝裂原活化蛋白激酶（MAPKs）途径降低促炎细胞因子和炎症介质，但这些受试多酚在炎症的另一个关键途径——核因子κB（NF-κB）信号通路中是否发挥重要作用仍不清楚。
在本研究中，我们分析了这些多酚通过Toll样受体4（TLR4）-NF-κB途径在脂多糖（LPS）诱导的RAW264.7巨噬细胞中的抗炎作用。
将不同浓度的PPPs、PC和EA与RAW264.7巨噬细胞预孵育，然后用LPS（1μg/mL）刺激，研究活性氧和TLR4的作用。此外，通过蛋白质免疫印迹法检测NF-κB p65的核转位和磷酸化以及IκB的降解。此外，通过酶联免疫吸附测定（ELISA）检测促炎细胞因子的影响。
我们的数据表明，PPPs、PC和EA抑制LPS诱导的细胞内活性氧产生，并以剂量依赖性方式抑制TLR4的mRNA和蛋白表达水平。此外，抗炎机制涉及阻断LPS诱导的磷酸化、IκB的降解和p65的核转位。此外，PPPs和PC表现出比EA更强的抗炎作用。
结果表明，PPPs具有强大的抗炎作用，PC是PPPs中的主要有效成分，这为利用PPPs预防炎症相关疾病提供了新的见解。
