基于尿毒症“浊毒攻心”理论探讨大黄改善TMAO相关血管内皮损伤的机制研究

Trimethylamine-N-oxide (TMAO), a product of gut microbiome and also a gut-derived uremic toxin, accumulates in chronic kidney disease (CKD) patients and impairs their vascular endothelium, leading to high incidence of cardiovascular events. In TCM theory, "turbid toxin attacking Heart" explains the phenomenon that CKD/uremia patients are tend to have life-threatening complications. Thus, Da Huang (Rheum Officinale) is commonly applied in clinical practice to remove turbidity or detoxify the harmed. However, the explicit mechanism is lacking. Previously we found that Rheum Officinale (both in a Chinese herbal compound manner and Emodin as its effective component) administered by colonic irrigation led to remodeling of intestinal flora against dysbiosis, accompanying with reduction of circular uremic toxin levels. In view of this, we propose such a hypothesis about its mechanism, i.e. Rheum Officinale lowers plasma level of TMAO by remodeling intestinal flora, and alleviates TMAO-induced endothelial injury by reducing associated inflammation and oxidative stress. This project aims to determine how Rheum Officinale affects the relationship chain consisting of “intestinal flora-TMAO-inflammation and oxidative stress-endothelial injury”, and demonstrate a detailed mechanism of Rheum relieving TMAO-induced endothelial injury. Methods including qReal Time-PCR and Bacterial gene sequencing will be applied to both quantitatively and qualitatively detect the bacteria in the gut. This work will contribute to clarifying the meaning of the detoxifying effect of Rheum and will provide new evidence for the appropriate use of Rheum to achieve a better outcome for CKD.

肠道细菌代谢产物——氧化三甲胺（TMAO）在慢性肾脏病患者体内蓄积并损害血管内皮功能，诱发心血管事件，是不可忽视的肠源性尿毒素。中医认为，“浊毒攻心”是尿毒症容易发生变证而威胁生命的关键病机，故首推大黄泄浊解毒以救心，但其具体机制尚不清楚。我们前期的临床和基础研究均提示，以大黄（复方或单体大黄素）进行灌肠治疗，可使肠道菌群发生良性改变，并伴随着血液循环毒素水平的下降。由此，我们提出以下新机制：大黄素通过重塑肠道菌群结构，抑制TMAO合成，从而降低血浆TMAO水平、减轻TMAO相关的炎症和氧化应激损伤，保护血管内皮。本研究拟通过qRT-PCR+细菌基因测序分析定量与定性结合的方法，探讨大黄在“肠道细菌-TMAO-炎症-氧化应激-血管内皮损伤”关系链上的作用环节，旨在明确大黄改善TMAO相关血管内皮损伤的机制，阐明大黄解毒祛邪的具体内涵，从而为临床上合理应用大黄改善尿毒症预后提供现代研究证据。

肠道细菌代谢产物——氧化三甲胺（TMAO）在慢性肾脏病患者体内蓄积并损害血管内皮功能，诱发心血管事件，是不可忽视的肠源性尿毒素。根据中医“浊毒攻心”理论，大黄泄浊解毒可救心，但其具体机制尚不清楚。本项目基于“肠道细菌-TMAO-炎症-氧化应激-血管内皮损伤”关系链探讨大黄灌肠对慢性肾衰大鼠肠道菌群和肠源性毒素TMAO及其前体、系统炎症、氧化应激等方面的影响及对肾脏、血管内皮等的影响。研究结果表明：（1）大黄灌肠可有效降低肾衰大鼠的血清TMAO和TMA水平，并伴有减轻系统炎症、改善肾脏病理的作用。（2）大黄灌肠对TMAO/TMA代谢的影响，并不是通过影响肝脏FMO3的表达，更大的可能性是通过改变肠道菌群结构，增加了一些共生菌和益生菌的丰度，同时减少了一些潜在的病原体的丰度。（3）大黄灌肠对肾衰大鼠的血管内皮功能损伤有一定的保护作用，表现为改善血管内皮依赖性舒张功能障碍；增加eNOS的表达。本研究表明：大黄灌肠可通过调整肠道菌群结构，降低血清TMAO水平，并减轻系统炎症，对抗氧化应激，从而产生改善肾脏病理，保护血管内皮功能的作用。