Mechanism by which astragalus-peach kernel alleviates renal fibrosis in chronic kidney disease rats

Abstract

BACKGROUND: Our previous studies have indicated that astragalus–peach kernel alleviates the progression of chronic kidney disease yet its precise mechanism remains to be elucidated. OBJECTIVE: To investigate the therapeutic effects and underlying mechanisms of astragalus-peach kernel in preventing renal fibrosis in chronic kidney disease rats. METHODS: (1) Gene expression profile chip datasets related to chronic kidney disease were retrieved and filtered via the Gene Expression Omnibus (GEO) database. Combined with network pharmacology, core targets of chronic kidney disease were screened, and molecular docking was performed to validate key genes. (2) Forty Sprague-Dawley rats were randomly divided into four groups: blank group (n=10) without modeling, model group (n=10), dapagliflozin group (n=10), and astragalus-peach kernel group (n=10). Chronic kidney disease was induced by intragastric administration of 2% adenine solution. After successful modeling, the blank and model groups received normal saline, the dapagliflozin group received dapagliflozin, and the astragalus-peach kernel group received astragalus-peach kernel (1:1) by gavage once daily for 8 weeks. After the last administration, serum creatinine and blood urea nitrogen levels were measured; renal tissue was examined by hematoxylin-eosin staining, Masson staining, and immunohistochemistry for α-smooth muscle actin and type I collagen; RT-qPCR detected mRNA expression of α-smooth muscle actin, type I collagen, transforming growth factor β, and c-Myc; western blot detected protein expression of α-smooth muscle actin, type I collagen, transforming growth factor β, c-Myc, Smad3, and p-Smad3. RESULTS AND CONCLUSION: (1) GEO database combined with network pharmacology identified 9 active components of astragalus-peach kernel and 7 core disease targets (c-Myc, RB1, CHUK, MAPK14, DPEP1, NR1I3, NQO2). KEGG enrichment analysis showed that the Ras-MAPK-c-Myc signaling pathway was related to chronic kidney disease. Molecular docking indicated strong binding ability between c-Myc and core drug components. (2) Compared with the blank group, the model group showed reduced glomerular structure and number, tubular inflammatory cell infiltration, fibroblast proliferation, abnormal collagen fiber deposition in the interstitium, and increased serum creatinine, blood urea nitrogen, and mRNA and protein expression of α-smooth muscle actin and type I collagen (P < 0.05). Compared with the model group, the astragalus-peach kernel group showed more intact renal morphology, reduced inflammatory infiltration and fibroblast proliferation, and decreased serum creatinine, blood urea nitrogen, and mRNA and protein expression of α-smooth muscle actin and type I collagen (P < 0.05). Compared with the blank group, the model group had increased mRNA and protein expression of c-Myc and transforming growth factor β, and increased protein expression of Smad3 and p-Smad3 (P < 0.05). Compared with the model group, these expressions were decreased in the astragalus-peach kernel group (P < 0.05). (3) These results indicate that astragalus-peach kernel can delay the progression of chronic kidney disease in SD rats, and the therapeutic mechanism may be related to the c-Myc/transforming growth factor β/Smad3 signaling pathway.

1. Introduction

Chronic kidney disease (CKD) is a chronic condition characterized by structural damage and functional abnormalities of the kidney, resulting from various causes including loss of parenchymal cells, chronic inflammation, fibrosis, and reduced regenerative capacity. International epidemiological surveys indicate that CKD affects 10%-14% of the global population, and the number of CKD patients in China is also substantial, imposing a huge economic burden on society and patients' families. Although angiotensin-converting enzyme inhibitors and angiotensin receptor blockers are the main clinical drugs to delay CKD progression, their protective effects are limited in patients with low glomerular filtration rate and without proteinuria, and they cannot significantly delay structural abnormalities such as renal fibrosis, which is a major cause of renal function decline. The occurrence of renal fibrosis is closely related to tubular injury and deposition of extracellular matrix in the kidney caused by inflammatory infiltration, but its complex molecular mechanisms have not been fully elucidated. Therefore, in-depth exploration of the mechanisms of renal fibrosis and seeking effective treatments are of great significance for the prevention and treatment of CKD.

In recent years, studies have shown that traditional Chinese medicine has unique advantages in the treatment of CKD. Chinese herbal medicines contain multiple bioactive components that can achieve comprehensive treatment of CKD through multi-target synergistic effects. According to the clinical symptoms of CKD (such as edema, fatigue, etc.), it can be classified as edema, deficiency syndrome, etc. in traditional Chinese medicine. Astragalus and peach kernel are commonly used traditional Chinese medicines. Astragalus has the effects of tonifying qi and consolidating the exterior, while peach kernel promotes blood circulation and removes blood stasis. The combination of astragalus and peach kernel has been used in clinical practice for the treatment of kidney diseases. Our previous studies have found that astragalus-peach kernel can alleviate the progression of CKD, but the underlying mechanism remains to be further verified.