Faculty of Life Science & Medicine, Northwest University, No. 229 Taibai North Road, Xi'an, Shaanxi 710069, China.
Division of Nephrology and Hypertension, School of Medicine, University of California Irvine, Irvine, California 92897, USA.
Phytomedicine. 2020 Jul;72:153232. doi: 10.1016/j.phymed.2020.153232. Epub 2020 May 17.
In chronic kidney disease, although fibrosis prevention is beneficial, few interventions are available that specifically target fibrogenesis. Poricoic acid A (PAA) isolated from Poria cocos exhibits anti-fibrotic effects in the kidney, however the underlying mechanisms remain obscure.
We isolated PAA and investigated its effects and the underlying mechanisms in renal fibrosis.
Unilateral ureteral obstruction (UUO) and 5/6 nephrectomy (Nx) animal models and TGF-β1-induced renal fibroblasts (NRK-49F) were used to investigate the anti-fibrotic activity of PAA and its underlying mechanisms.
Western blots, qRT-PCR, immunofluorescence staining, co-immunoprecipitation and molecular docking methods were used. Knock-down and knock-in of adenosine monophosphate-activated protein kinase (AMPK) in the UUO model and cultured NRK-49F cells were employed to verify the mechanisms of action of PAA.
PAA improved renal function and alleviated fibrosis by stimulating AMPK and inhibiting Smad3 specifically in Nx and UUO models. Reduced AMPK activity was associated with Smad3 induction, fibroblast activation, and the accumulation and aberrant remodelling of extracellular matrix (ECM) in human renal puncture samples and cultured NRK-49F cells. PAA stimulated AMPK activity and decreased fibrosis in a dose-dependent manner, thus showing that AMPK was essential for PAA to exert its anti-fibrotic effects. AMPK deficiency reduced the anti-fibrotic effects of PAA, while AMPK overexpression enhanced its effect.
PAA activated AMPK and further inhibited Smad3 specifically to suppress fibrosis by preventing aberrant ECM accumulation and remodelling and facilitating the deactivation of fibroblasts.
在慢性肾脏病中，虽然预防纤维化有益，但针对纤维化发生的干预措施却很少。从多孔菌科真菌茯苓中分离得到的茯苓酸 A（PAA）在肾脏中具有抗纤维化作用，但具体的作用机制尚不清楚。
本研究分离了 PAA，探讨了其在肾纤维化中的作用及其潜在机制。
单侧输尿管梗阻（UUO）和 5/6 肾切除（Nx）动物模型以及 TGF-β1 诱导的肾成纤维细胞（NRK-49F）用于研究 PAA 的抗纤维化活性及其潜在机制。
采用 Western blot、qRT-PCR、免疫荧光染色、免疫共沉淀和分子对接方法。在 UUO 模型和培养的 NRK-49F 细胞中敲低和敲入腺苷单磷酸激活蛋白激酶（AMPK），以验证 PAA 的作用机制。
PAA 通过特异性刺激 AMPK 并抑制 Smad3，改善了 Nx 和 UUO 模型的肾功能并减轻了纤维化。AMPK 活性降低与 Smad3 诱导、成纤维细胞激活以及细胞外基质（ECM）在人肾穿刺样本和培养的 NRK-49F 细胞中的积累和异常重塑有关。PAA 以剂量依赖的方式刺激 AMPK 活性并减少纤维化，表明 AMPK 是 PAA 发挥抗纤维化作用所必需的。AMPK 缺乏会降低 PAA 的抗纤维化作用，而 AMPK 过表达则增强了其作用。
PAA 通过防止异常 ECM 积累和重塑并促进成纤维细胞失活，特异性地激活 AMPK 并进一步抑制 Smad3，从而抑制纤维化。
