黄芪甲苷上调Piezo2促进肠嗜铬细胞分泌5-HT在慢传输型便秘治疗中的机制研究

Slow transit constipation (STC) is a common gastrointestinal complaint that caused by multiple factors and the pathogenesis of STC remains unclear. Enterochromaffin cells and 5-HT signaling are closely linked with the pathogenesis of STC. Recent studies show that mechanosensitive ion channel Piezo2 is specifically expressed in EC and is critical for EC response to mechanical forces and the activation of Piezo2 by force leads to inward currents, 5-HT release and an increase in mucosal secretion. Our preliminary data showed that the Piezo2 was expressed with a high level in rectal mucosa of STC patients compared with normal control and the Astragaloside IV increased the Piezo2 expression in the rectal mucosa of STC patients. Here, we hypothesize that the Astragaloside IV increase the release of 5-HT by enterochromaffin cells through upregulating Piezo2 expression in the treatment of slow transit constipation. Therefore, in this study, we are going to investigate the effect of different doses of Astragaloside IV on expression of Piezo2 in the EC and the relationship between Astragaloside IV and EC and 5-HT signaling using STC rats. The aim of this study is 1) to clarify the mechanism for the treatment of STC using Astragaloside IV; 2) to reveal the role of Piezo2 in the enterochromaffin cells and 5-HT signaling; 3) to reveal the role of PIEZO2 in the pathogenesis of SCT. The investigation of those will provide the scientific evidence of traditional Chinese medicine in the treatment of STC and provide scientific basis of individualized treatment of STC patient.

慢传输型便秘（slow transit constipation，STC）是一种特发性、多因素共同干预的复杂疾病，其发病机制尚不明确。肠嗜铬细胞（enterochromaffin cell，EC）介导5羟色胺信号通路与STC的发病机制密切相关。研究发现EC特异性表达机械敏感性离子通道Piezo2蛋白并对其受到压力后释放5-HT和粘膜分泌至关重要。我们前期研究发现：STC患者直肠粘膜Piezo2蛋白表达水平高于正常直肠粘膜，且进一步研究发现黄芪甲苷可以促进STC患者Piezo2蛋白表达。因此，本研究拟通过构建STC大鼠模型，研究不同剂量的黄芪甲苷对EC细胞Piezo2的表达水平的影响；及其影响Piezo2表达水平与EC介导的5-HT信号通路的关系。通过本研究我们将阐明黄芪甲苷治疗STC的作用机制，为中医药治疗STC提供现代科学依据；揭示Piezo2在肠嗜铬细胞介导的5羟色胺信号通路中的作用。

慢传输型便秘(slow transit constipation ，STC)是一种特发性多因素疾病，其发病机制尚不清楚。根据文献，肠嗜铬细胞(enterochromaffin cells, ECs)的数量或表型异常与STC的发病密切相关。Piezo2蛋白是一种离子通道蛋白，在ECs中特异性表达，对刺激下ECs 5-HT的释放和粘液分泌至关重要。既往研究表明STC患者直肠黏膜中Piezo2蛋白水平高于正常直肠黏膜，黄芪甲苷（astragaloside IV，AS-IV）促进了STC患者中Piezo2蛋白的表达。因此，本研究旨在通过构建STC小鼠模型，通过粪便16S rDNA测序、粪便细菌移植技术、代谢组学测序和转录组测序，探讨AS-IV在体内外治疗STC的影响。结果表明，AS-IV促进了Eubacterium fissicatena组的定殖，降低了Ligilactobacillus和Lachnospiraceae NK4A136组和Candidatus益生菌的水平。此外，通过代谢组学测序，我们发现代谢物3-bromotyrosine (3-BrY)减少了ECs的caspase依赖性凋亡，并抑制洛哌丁胺诱导的p38 MAPK和ERK信号通路的激活来保护细胞存活，并促进细胞中Piezo2蛋白的表达，促进粘膜分泌增加，最终促进肠道的肠动。