Bupi Yishen formula may prevent kidney fibrosis by modulating fatty acid metabolism in renal tubules.

BACKGROUND: Bupi Yishen formula (BYF), a traditional Chinese herbal mixture, has demonstrated better effectiveness than Losartan in preserving renal function and preventing composite severe adverse outcomes in patients with advanced chronic kidney disease (CKD) in a recent randomized controlled trial. Prior studies have shown that BYF exerts anti-inflammatory and anti-fibrotic effects in the kidneys of CKD models, but the underlying mechanisms have not been fully elucidated. PURPOSE: The aim of this study was to investigate the protective effects of BYF administration on profibrotic phenotypic changes in the kidney and to elucidate its fundamental mechanisms of action. METHODS: Adenine and 5/6 nephrectomy rat models were administered with two doses of BYF extract (15 or 30 g/kg/d) by intragastric administration, and Losartan treatment was used as a positive control group. The relationship between BYF renoprotection and restoration of fatty acid dysregulation was examined using the two fibrosis models and TGFb1-induced human tubular HK2 cells. Transcriptomic profiles of the fibrotic kidneys obtained from adenine-induced CKD rats were used to identify the key mechanisms that are affected by BYF intervention. Human relevance and clinical implications were established by re-analysis of the microarray databases of CKD patients and immunostaining on human biopsy specimens. RESULTS: BYF effectively prevented kidney histological damage and ameliorated renal malfunction in the adenine rat model of CKD. BYF robustly attenuated the significant increase in profibrotic and proapoptotic markers in fibrotic kidneys of adenine-induced CKD rats. Transcriptomic analyses of the fibrotic kidneys of the adenine rats identified fatty acid metabolism as the key dysregulated pathway affected by BYF prevention. BYF significantly reversed defective fatty acid oxidation (FAO) and the intracellular lipids accumulation in the fibrotic kidneys induced by 5/6 nephrectomy. Furthermore, BYF prevented dysfunctional fatty acid metabolism, which were associated with the significant improvement of TGFb1-induced profibrotic changes in HK2 human proximal tubular cells. Furthermore, analyses of kidney microarray databases and biopsy specimens of CKD patients suggested that FAO defect is common in CKD in humans. CONCLUSION: Our exploratory study found that BYF may exert protective effects on renal fibrosis by regulating the fatty acid metabolism of renal tubular cells, which may be a key mechanism for preventing kidney fibrosis in CKD.

Protective effects of the Bupi Yishen formula on renal fibrosis through PI3K/AKT signaling inhibition.

ETHNOPHARMACOLOGICAL RELEVANCE: The Bupi Yishen Formula (BYF) is a patented Chinese herbal compound that has been long used to treat chronic kidney disease (CKD) in the clinic. However, its main active ingredients and underlying mechanisms remain to be elucidated. AIM: Identify the major active ingredients of BYF and investigate its protective effects and specific molecular mechanisms in renal fibrosis. METHODS: First, we performed network pharmacology analysis combined with molecular docking to predict the main active compounds, potential therapeutic targets, and intervention pathways that might exert the anti-fibrotic effect of BYF in the kidney. Then, we validated the predictions in both adenine-induced CKD rats and TGFß1-induced HK-2 cells. RESULTS: A total of 233 common targets, 25 core targets, and 10 main active compounds from BYF were selected by network pharmacology analyses. Then, GO and KEGG functional enrichment analyses indicated that the renoprotection conferred by BYF against renal fibrosis was mainly associated with the PI3K/AKT signaling. Besides, the molecular docking showed that the 10 main active compounds of BYF were closely docked with three main PI3K/AKT pathway proteins. During the experimental validations, BYF improved renal impairment and alleviated fibrosis by inhibiting the PI3K/AKT signaling activity in the kidney of adenine-induced CKD model rats. Moreover, increased PI3K/AKT signaling activation was associated with fibrotic phenotype changes in adenine-induced CKD rats and TGFß1-induced HK-2 cells. On the other hand, BYF treatment reduced PI3K/AKT signaling activation and decreased renal fibrogenesis in a dose-dependent manner, thereby indicating that PI3K/AKT signaling was essential for BYF to exert its anti-fibrotic effects. Finally, the inhibitory effect of BYF on renal fibrogenesis was not enhanced while blocking the PI3K/AKT pathway with a broad spectrum PI3K inhibitor (LY294002). CONCLUSION: In the present study, we applied a comprehensive strategy based on systemic pharmacology to reveal the anti-fibrotic mechanisms of BYF, at least partially, through the inhibition of PI3K/AKT signaling activation. We also identified BYF as a potential therapeutic agent for renal fibrosis and CKD progression.

ROS-ERK Pathway as Dual Mediators of Cellular Injury and Autophagy-Associated Adaptive Response in Urinary Protein-Irritated Renal Tubular Epithelial Cells.

ERK, an extracellular signal-regulated protein kinase, is involved in various biological responses, such as cell proliferation and differentiation, cell morphology maintenance, cytoskeletal construction, apoptosis, and canceration of cells. In this study, we focused on ERK pathway on cellular injury and autophagy-associated adaptive response in urinary protein-irritated renal tubular epithelial cells and explored the potential mechanisms underlying it. By using antioxidants N-acetylcysteine and catalase, we found that ERK pathway was activated by a reactive oxygen species- (ROS-) dependent mechanism after exposure to urinary proteins. What is more, ERK inhibitor U0126 could decrease the release of neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), and the number of apoptotic cells induced by urinary proteins, indicating the damaging effects of ERK pathway in mediating cellular injury and apoptosis in HK-2 cells. Interestingly, we also found that the increased expression of microtubule-associated protein 1 light chain 3 (LC3)-II (a key marker of autophagy) and the decreased expression of p62 (autophagic substrate) induced by urinary proteins were reversed by U0126, suggesting autophagy was activated by ERK pathway. Furthermore, rapamycin reduced urinary protein-induced NGAL and KIM-1 secretion and cell growth inhibition, while chloroquine played the opposite effect, indicating that autophagy activation by ERK pathway was an adaptive response in the exposure to urinary proteins. Taken together, our results indicate that activated ROS-ERK pathway can induce cellular injury and in the meantime provide an autophagy-associated adaptive response in urinary protein-irritated renal tubular epithelial cells.