Haihe Laboratory of Modern Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China.
State Key Laboratory of Medicinal Chemical Biology, College of Pharmacy and Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin, China.
J Ethnopharmacol. 2024 May 10;325:117825. doi: 10.1016/j.jep.2024.117825. Epub 2024 Jan 30.
As a classic traditional Chinese medicine, Magnolia officinalis (M. officinalis) is widely used in digestive diseases. It has rich gastrointestinal activity including inflammatory bowel disease (IBD) treatment, but the mechanism is not clear.
In recent years, there has been a growing interest in investigating the regulatory effects of herbal compounds on transient receptor potential (TRP) channel proteins. Transient receptor potential vanilloid 4 (TRPV4), a subtype involved in endothelial permeability regulation, was discussed as the target of M. officinalis in the treatment of IBD in the study. Based on the targeting effect of TRPV4, this study investigated the active ingredients and mechanism of M. officinalis extract in treating IBD.
To reveal the connection between the active ingredients in M. officinalis and TRPV4, a bioactivity-guided high performance liquid chromatography system coupled with mass spectrometry identification was utilized to screen for TRPV4 antagonists. TRPV4 siRNA knockdown experiment was employed to validate the significance of TRPV4 as a crucial target in regulating endothelial permeability by honokiol (HON). The interaction of the active ingredient representing HON with TRPV4 was confirmed by molecular docking, fluorescence-based thermal shift and live cell calcium imaging experiments. The potential binding sites and inhibitory mechanisms of HON in TRPV4 were analyzed by molecular dynamics simulation and microscale thermophoresis. The therapeutic effect of HON based on TRPV4 was discussed in DSS-IBD mice.
Our finding elucidated that the inhibitory activity of M. officinalis against TRPV4 is primarily attributed to HON analogues. The knockdown of TRPV4 expression significantly impaired the calcium regulation and permeability protection in endothelial cells. The mechanism study revealed that HON specifically targets the Q239 residue located in the ankyrin repeat domain of TRPV4, and competitively inhibits channel opening with adenosine triphosphate (ATP) binding. The immunofluorescence assay demonstrated that the administration of HON enhances the expression and location of VE-Cadherin to protect the endothelial barrier and attenuates immune cell infiltration.
The finding suggested that HON alleviates IBD by improving endothelial permeability through TRPV4. The discovery provides valuable insights into the potential therapeutic strategy of active natural products for alleviating IBD.
作为一种经典的中药，厚朴（Magnolia officinalis）广泛用于消化系统疾病。它具有丰富的胃肠道活性，包括炎症性肠病（IBD）的治疗，但机制尚不清楚。
近年来，人们对研究草药化合物对瞬时受体电位（TRP）通道蛋白的调节作用越来越感兴趣。瞬时受体电位香草酸 4（TRPV4）是一种参与内皮通透性调节的亚型，在该研究中被认为是厚朴治疗 IBD 的靶点。基于 TRPV4 的靶向作用，本研究探讨了厚朴提取物治疗 IBD 的活性成分和机制。
为了揭示厚朴中活性成分与 TRPV4 之间的联系，采用基于生物活性的高效液相色谱系统与质谱鉴定相结合的方法筛选 TRPV4 拮抗剂。采用 TRPV4 siRNA 敲低实验验证 honokiol（HON）作为调节内皮通透性的关键靶点的重要性。通过分子对接、荧光热转移和活细胞钙成像实验证实了活性成分代表 HON 与 TRPV4 的相互作用。通过分子动力学模拟和微量热泳实验分析了 HON 在 TRPV4 中的潜在结合位点和抑制机制。在 DSS-IBD 小鼠中探讨了基于 TRPV4 的 HON 的治疗效果。
我们的研究结果表明，厚朴对 TRPV4 的抑制活性主要归因于 HON 类似物。TRPV4 表达的敲低显著损害了内皮细胞中的钙调节和通透性保护。机制研究表明，HON 特异性靶向 TRPV4 中的 ankyrin 重复结构域中的 Q239 残基，并与三磷酸腺苷（ATP）结合竞争抑制通道开放。免疫荧光实验表明，HON 的给药可增强 VE-Cadherin 的表达和定位，以保护内皮屏障并减轻免疫细胞浸润。
研究结果表明，HON 通过改善内皮通透性来缓解 IBD，通过 TRPV4。该发现为缓解 IBD 的活性天然产物潜在治疗策略提供了有价值的见解。
