Research and Development Centre for Natural Health Products, HKBU Institute for Research and Continuing Education, Shenzhen, China; Consun Chinese Medicines Research Centre for Renal Diseases, School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, China.
Department of Food and Biological Engineering, Zhangzhou Institute of Technology, China.
Phytomedicine. 2022 Jul 20;102:154194. doi: 10.1016/j.phymed.2022.154194. Epub 2022 May 23.
Uncontrolled inflammation causes health problems. Extracellular signal-regulated kinase (ERK) phosphorylates signal transducer and activator of transcription 3 (STAT3) at Ser727, resulting in inflammation. The leaf of Vernonia amygdalina (VA) is a medicinal herb for managing inflammation-associated diseases. Oral administration or topical application of VA leaf extract exerts anti-inflammatory effects in rat models. However, the anti-inflammatory mechanisms of the herb are not fully understood.
In this study, we aimed to investigate the involvement of ERK/STAT3 (Ser727) signaling in the anti-inflammatory effects of an ethanolic extract of VA leaves.
Extracts of VA leaves were prepared with different concentrations of ethanol. A LPS-stimulated RAW264.7 cell model was used for in vitro assays, and a TPA (12-O-tetradecanoylphorbol-13-acetate)-induced ear edema mouse model was employed for in vivo assays. The 95% ethanol extract of VA leaves (VAE) exerted the strongest inhibitory effect on nitric oxide (NO) production in LPS-stimulated macrophages; thus it was selected for use in this study. Hematoxylin and eosin (H&E) staining was used to examine pathological conditions of mouse ear tissues. Griess reagent was employed to examine NO generation in cell cultures. Immunoblotting and ELISA were used to examine protein levels, and RT-qPCR was employed to examine mRNA levels.
Topical application of VAE ameliorated mouse ear edema induced by TPA. VAE suppressed the phosphorylation of ERK (Thr202/Tyr204) and STAT3 (Ser727); and decreased protein levels of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), interleukin (IL)-6, IL-1β and tumor necrosis factor-α (TNF-α) in the mouse ear tissues and in LPS-stimulated RAW 264.7 cells. VAE also inhibited NO production, and lowered mRNA levels of IL-6, IL-1β and TNF-α in the macrophages.
VAE ameliorates TPA-induced mouse ear edema. Suppression of ERK/STAT3 (Ser727) signaling is involved in VAE's anti-inflammatory effects. These novel data provide further pharmacological justifications for the medicinal use of VA in treating inflammation-associated diseases, and lay the groundwork for developing VAE into a new anti-inflammatory agent.
失控的炎症会导致健康问题。细胞外信号调节激酶（ERK）在丝氨酸 727 位磷酸化信号转导和转录激活因子 3（STAT3），从而引发炎症。马缨丹叶是一种用于治疗炎症相关疾病的草药。在大鼠模型中，口服或局部应用马缨丹叶提取物具有抗炎作用。然而，这种草药的抗炎机制尚不完全清楚。
本研究旨在探讨 ERK/STAT3（丝氨酸 727）信号通路在马缨丹叶乙醇提取物抗炎作用中的参与情况。
用不同浓度的乙醇制备马缨丹叶提取物。采用脂多糖（LPS）刺激的 RAW264.7 细胞模型进行体外试验，采用 TPA（12-O-十四烷酰佛波醇-13-乙酸酯）诱导的耳肿胀小鼠模型进行体内试验。马缨丹叶 95%乙醇提取物（VAE）对 LPS 刺激的巨噬细胞中一氧化氮（NO）的产生有最强的抑制作用；因此，选择它用于本研究。苏木精-伊红（H&E）染色用于观察小鼠耳组织的病理状况。Griess 试剂用于检测细胞培养物中 NO 的生成。免疫印迹和 ELISA 用于检测蛋白水平，RT-qPCR 用于检测 mRNA 水平。
局部应用 VAE 可改善 TPA 诱导的小鼠耳肿胀。VAE 抑制 ERK（Thr202/Tyr204）和 STAT3（Ser727）的磷酸化；并降低小鼠耳组织和 LPS 刺激的 RAW 264.7 细胞中诱导型一氧化氮合酶（iNOS）、环加氧酶-2（COX-2）、白细胞介素（IL）-6、IL-1β 和肿瘤坏死因子-α（TNF-α）的蛋白水平。VAE 还抑制了 NO 的产生，并降低了巨噬细胞中 IL-6、IL-1β 和 TNF-α 的 mRNA 水平。
VAE 可改善 TPA 诱导的小鼠耳肿胀。抑制 ERK/STAT3（丝氨酸 727）信号通路参与了 VAE 的抗炎作用。这些新数据为马缨丹叶在治疗炎症相关疾病中的药用提供了进一步的药理学依据，并为将 VAE 开发成一种新的抗炎药物奠定了基础。
