The combination of Astragalus membranaceus and Salvia miltiorrhiza (AS) is an effective prescription that is widely used to treat chronic kidney disease (CKD) clinically in traditional Chinese medicine. Our previous studies have shown that AS can alleviate early CKD through the "gut-kidney axis", but the regulatory role of AS in the "gut-kidney axis" in the middle and late stages of CKD caused by cyclosporin A-induced chronic nephrotoxicity (CICN) has remained unclear.
Aim of the study
To explore the protective effect of AS by regulating the intestinal flora to further control the miRNA-mRNA interaction profiles in CICN.
Materials and methods
Thirty-two mice were divided into four groups: Normal (N) (olive oil), Model (M) (CsA, 30 mg kg⁻¹ d⁻¹), AS (CsA + AS, 30 + 8.4 g kg⁻¹ d⁻¹) and FMT-AS (CsA + Faeces of AS group, 30 mg + 10 mL kg⁻¹ d⁻¹). The mice were treated for 6 weeks. Changes in renal function related metabolites were detected, pathological changes in the colon and kidney were observed, and 16S rDNA sequencing was performed on mouse faeces. In addition, miRNA and mRNA sequencing were performed on the kidney to construct differential expression (DE) profiles of the other 3 groups compared with group M. The target mRNAs among the DE miRNAs were then predicted, and an integrated analysis was performed with the DE mRNAs to annotate gene function by KEGG. DE miRNAs and DE mRNAs related to CICN in the overlapping top 20 KEGG pathways were screened and verified.
Eight metabolites that could worsen renal function were increased in group M, accompanied by thickening of the glomerular basement membrane, vacuolar degeneration of renal tubules, and proliferation of collagen fibres, while AS and FMT-AS intervention amended these changes to varying degrees. Simultaneously, intestinal permeability increased, the abundance and diversity of the flora decreased, and the ratio of Firmicum to Bacteroides (F/B) increased in group M. The AS and FMT-AS treatments reversed the flora disorder and increased probiotics producing butyric acid and lactic acid, especially Akkermansia and Lactobacillus, which might regulate the 12 overlapping top 20 KEGG pathways, such as Butanoate metabolism, Tryptophan metabolism and several RF-related pathways, leading to the remission of renal metabolism. Finally, 15 DE miRNAs and 46 DE mRNAs were screened as the therapeutic targets, and the results coincided with the sequencing results.
AS could alleviate renal fibrosis and metabolism caused by CICN through the "gut-kidney axis". Probiotics such as Akkermansia and Lactobacillus were the primary driving factors, and the miRNA-mRNA interaction profiles, especially Butanoate metabolism and Tryptophan metabolism, may be an important subsequent response and regulatory mechanism.