Amomum tsao-ko volatile oil alleviates renal fibrosis in 5/6 nephrectomy rats through TGF-β1/SMAD3 and PI3K/AKT signaling pathways

Introduction Renal fibrosis is the main cause of many kidney diseases and a common outcome of many chronic kidney diseases. The dried mature fruit of Amomum tsao-ko is widely used to treat various diseases, including those characterized by diuresis and detumescence. Amomum tsao-ko volatile oil (AO) may be the active ingredient responsible for its main pharmacological action, and its protective effect and mechanism in kidney injury models are unclear. Therefore, based on transcriptomics and animal experiments, this study discusses the mechanism of AO through TGF‑ β 1/SMAD3 and PI3K/AKT signaling pathways in renal fibrosis of 5/6 nephrectomy rats. Methods Seventy-two healthy SD rats were randomly divided into 6 groups. The rat renal fibrosis model was established by 5/6 nephrectomy. Different doses of AO were given by gavage. After 28 days of continuous administration, the levels of creatinine and urea nitrogen in serum of rats were detected. The total RNA of rat kidney tissue was extracted for transcriptomics determination and analysis showed the expression of differential genes in each group. The core targets related to chronic kidney injury were docked with the main components of the AO. HE, PAS and Masson staining were used to observe the pathological morphology of renal tissue in rats. Western Blot was used to detect the expression of p-PI3K, PI3K, AKT, p-AKT, SMAD3, TGF- β 1, MMP-9 and TIMP-1 in renal tissue. Results Compared with the Sham group, the transcriptome results showed that there were 823 genes with significant differences in expression; the levels of SCr and BUN in the model group were significantly increased. HE, PAS and Masson found that 5/6 Nx could develop interstitial fibrosis. At the same time, a large number of renal tubular epithelial cells were atrophied, deformed and exfoliated, and a large number of inflammatory cells infiltrated in the interstitium. Western Blot results showed that the expression of PI3 K, AKT, TIMP-1, SMAD3, TGF- β 1 and other proteins in the 5/6 Nx group increased significantly, and the expression of MMP-9 protein decreased significantly. Compared with the 5/6 Nx group, there were 1,009 genes with significant differences in expression after treatment with AO, and the levels of SCr and BUN decreased. The infiltration of inflammatory cells in renal tissue was improved. The expression of PI3K, AKT, TIMP-1, SMAD3 and TGF- β 1 was significantly decreased, and the expression of MMP-9 was significantly increased. Conclusion AO can further inhibit the phosphorylation level by inhibiting the TGF- β 1/SMAD3 and PI3K/AKT signaling pathways in 5/6 Nx rats, thus effectively improving the pathological damage of renal tissue.