天然苯乙醇苷抑制钙通透TRPV3通道的药理学特征和抗瘙痒机制研究

Chronic pruritus strongly impairs affected individuals’quality of life. Histamine is the best-known pruritogen and has been regarded as a main target for antipruritic therapies, but histamine receptor antagonists are often ineffective against chronic pruritus. It is suggested that mediators other than histamine receptor have a key role in chronic pruritus. Our recent identification of gain-of-function mutations in human TRPV3 from patients with Olmsted syndrome characterized by severe itching unveils a critical role of TRPV3 channel in itch sensation. However, due to the lack of specific TRPV3 antagonists, the molecular mechanism of TRPV3 channel in itch signaling is still unclear. We recently found that natural phenylethanoid glycosides specially inhibited TRPV3 channel and attenuated chronic pruritus. In this proposal, we aim to investigate the pharmacological characterizations and antipruritic mechanisms of natural phenylethanoid glycosides inhibiting calcium-permeable TRPV3 channel. Understanding the role of TRPV3 channel in chronic pruritus may lead to validation of TRPV3 as a target. We're also going to find protein binding pocket by molecular docking, channel mutagenesis and point mutations. Understanding the structural mechanism for the interactions between phenylethanoid glycosides and TRPV3 may provide more reasonable design ideas for TRPV3 inhibitors.

慢性瘙痒严重影响患者的生活质量和精神状态。目前临床上治疗慢性瘙痒的药物主要是以组胺受体为靶点的抗组胺类药物，但存在疗效有限、副作用大等问题。因此，亟待发现与慢性瘙痒相关的新靶标和靶向性调节剂。我们前期研究发现，钙通透TRPV3通道功能增强性点突变能引发人类皮肤剧烈瘙痒，提示TRPV3通道在皮肤瘙痒的发生过程中扮演重要角色。然而由于缺少特异性工具药，TRPV3通道在慢性瘙痒中的作用机制尚不清楚。最近我们研究发现，天然苯乙醇苷是TRPV3通道的特异性抑制剂，并能缓解小鼠皮肤瘙痒。因此，本项目将对靶向TRPV3通道的天然苯乙醇苷的药理学特征和抗瘙痒机制进行深入研究，阐明TRPV3通道下游瘙痒信号通路，为确证TRPV3通道是慢性瘙痒治疗的新靶标提供充分的理论依据；我们还将利用分子对接、嵌合体、点突变等手段阐明苯乙醇苷与TRPV3通道相互作用的结构基础，为设计TRPV3通道特异性抑制剂提供新思路。

慢性瘙痒是未满足的临床需求，亟待发现与慢性瘙痒相关的新靶标和靶向性调节剂。我们前期研究发现，TRPV3通道在皮肤瘙痒的发生过程中扮演重要角色，天然苯乙醇苷能靶向抑制TRPV3通道缓解小鼠皮肤瘙痒。在本项目的资助下，我们对靶向TRPV3通道的天然苯乙醇苷的药理学特征和抗瘙痒机制进行深入研究。通过构效关系分析，明确了咖啡酰基是天然苯乙醇苷抑制TRPV3通道的关键活性基团，发现了一系列含有咖啡酰基的TRPV3高效选择性抑制剂。利用皮肤瘙痒和炎症动物模型，评价了含单咖啡酰基的毛蕊花糖苷以及含双咖啡酰基的异绿原酸A和异绿原酸B对小鼠搔抓行为、耳肿胀及皮肤炎症的抑制作用及抗瘙痒机制，为治疗皮肤炎症和瘙痒新药研发提供了先导化合物，为确证TRPV3通道是皮肤瘙痒治疗的新靶标提供充分的实验及理论依据。通过分子对接、点突变等手段，阐明了异绿原酸A和异绿原酸B抑制TRPV3通道以及香芹酚激活TRPV3通道的分子机制，揭示了这些天然调节剂与TRPV3通道相互作用的结合口袋及关键氨基酸，为设计TRPV3特异性调节剂提供新思路。此外，本项目执行过程中发现硝基苯类皮炎敏化剂能靶向激活TRPA1通道，并阐明该类化合物与TRPA1通道相互作用的结构基础，为TRPA1通道功能的研究提供了一个新的药理学工具。