黄葵四物方调控肠源尿毒素代谢途径和作用通路干预慢性肾病进展的机理研究

Gut derived uremic toxins (GDUT) are co-metabolites of gut microbiota and host. The accumulation of GDUT are associated with chronic kidney disease (CKD) progression and also contribute to the progression of CKD. Targeting the generation and metabolic pathway of GDUT are research interest for retarding the progression of CKD, while no safe and effective method has been reported to intervene this pathway. We found that Huangkuisiwufang could decrease the concentration of a kind of GDUT compound p-cresol sulfate (PCS) in vivo, and improve renal injury in CKD model rats. We propose that Huangkuisiwufang improve renal injury through modulating the generation, metabolic pathway and action of PCS. The following studies will be carried out: (1) To investigate the influence of Huangkuisiwufang on the generation of PCS percusor in colon and elucidate the machanism of action on regulating gut microbiota, specific bacteria and related key enzyme. (2) To investigate the effect of Huangkuisiwufang on the generation of PCS in colon mucosa and liver, and further elucidate the machanism of action such as regulation of specific enzyme SULT. (3) To investigate the influence of Huangkuisiwufang on the transportation of PCS into kidney and PCS induced oxidative stress, and further elucidate the signaling pathway related with regulating kidney transporter OAT and specifice enzyme Nox4. The object of our project is to systematically clarify the mechanisms of action of Huangkuisiwufang for the treatment of CKD through regulating the generation and metabolic pathway of GDUT, and will contribute to set up a novel strategy to slow down the progression of CKD.

肠源尿毒素是肠道细菌-机体共代谢产物，其体内堆积是加速慢性肾病（CKD）进展的重要原因。减少肠源尿毒素的生成、阻断其作用通路，以延缓CKD进展是国内外研究的热点，但目前仍缺乏安全有效的干预方式。申请者发现，黄葵四物方可减少肠源尿毒素类成分硫酸对甲酚（PCS）的体内堆积，改善CKD模型大鼠的肾脏损伤。提出：黄葵四物方可调控PCS代谢途径和作用通路，减少PCS堆积，阻断PCS作用，减轻肾脏损伤。拟开展研究（1）黄葵四物方对PCS前体在肠道内合成的影响，阐明其对肠道细菌及关键代谢酶的调控机制；（2）黄葵四物方对PCS在肠黏膜及肝脏内合成的影响，明确其对PCS合成酶的调控机制；（3）黄葵四物方对PCS肾小管细胞内转运及作用通路的影响，揭示其对肾脏转运体及Nox酶的调控机制。本项目以黄葵四物方为范例，开展药物调控PCS减轻肾脏损伤的作用机制研究，探索药物靶向肠源尿毒素延缓CKD进展的研究模式。

肠源尿毒素是肠道细菌-宿主共代谢产物，其体内堆积是加速慢性肾病（CKD）进展的重要原因。减少肠源尿毒素的生成、阻断其作用通路，以延缓CKD进展是国内外研究的热点，但目前仍缺乏安全有效的干预方式。申请者在前期研究基础上提出：黄葵四物方可调控PCS代谢途径和作用通路，减少PCS堆积，阻断PCS作用，减轻肾脏损伤。本项目拟进一步探讨黄葵四物方对PCS前体在肠道内合成的影响，阐明其对肠道细菌及关键代谢酶的调控机制；探讨黄葵四物方对PCS在肠黏膜及肝脏内合成的影响，明确其对PCS合成酶的调控机制；探讨黄葵四物方对PCS肾小管细胞内转运及作用通路的影响，揭示其对肾脏转运体及Nox酶的调控机制。结果发现，黄葵四物方对CKD大鼠肠道菌群具有一定程度的调节作用，但是未表现出显著差异，提示黄葵四物方并不是通过直接抑制细菌的丰度来降低对甲酚含量的，可能与其抑制肠道菌群中对甲酚的合成途径有关。进一步研究也证实了这种推测，发现黄葵四物方可显著抑制肠道细菌生成对甲酚。黄葵四物方可促使酪氨酸代谢过程中氧化途径向还原途径转化，导致氧化途径中对甲酚的生成显著减少；而对肠道细菌中生成对甲酚的氧化途径具有直接的抑制作用，抑制对羟基苯乙酸分解生成对甲酚。提示黄葵四物方可通过调控肠道菌群中尿毒素代谢通路, 多环节抑制肠道菌群中尿毒素前体生成。我们接下来观察了黄葵四物方对宿主中PCS代谢通路的影响。结果发现黄葵四物方可显著抑制肝脏内磺基转移酶的表达，从而抑制对甲酚向PCS转化，并最终抑制体内PCS的生成。黄葵四物方并不影响PCS向肾脏内的转运环节。以上研究表明黄葵四物方可通过调控肠道菌群中对甲酚代谢通路，干预肝脏内PCS代谢酶的表达来减少体内PCS蓄积。本项目以黄葵四物方为范例，开展药物调控PCS减轻肾脏损伤的作用机制研究，探索药物靶向肠源尿毒素延缓CKD进展的研究模式。