Protective Effects of Orally Administered Salvia miltiorrhiza–Derived Extracellular Vesicles on Diabetic Kidney Disease: Protection Mediated by Gut Microbiota and Metabolomic Remodeling

Purpose: Diabetic kidney disease (DKD) is one of the most common and severe microvascular complications of diabetes, characterized by glomerulosclerosis and tubulointerstitial fibrosis. Growing evidence indicates that gut dysbiosis and metabolic imbalance contribute to DKD progression. Salvia miltiorrhiza possesses anti-inflammatory, antioxidative, and antifibrotic activities, while Salvia miltiorrhiza ‐derived Extracellular Vesicle (SMEVs), as natural nano-carriers, exhibit favorable bioactivity and targeting potential. Methods: SMEVs were isolated and purified using differential centrifugation combined with sucrose density gradient ultracentrifugation. Transmission electron microscopy and nanoparticle tracking analysis confirmed their typical bilayer membrane and an average diameter of approximately 163.6 nm. BKS.DB mice were orally administered SMEVs for 6 weeks, followed by evaluation of renal function, histopathology, and molecular markers. Results: SMEV treatment significantly improved glucose and lipid metabolism, reduced proteinuria, alleviated renal dysfunction, and mitigated renal fibrosis in DKD mice. 16S rRNA sequencing revealed that SMEVs reshaped the gut microbial community by increasing beneficial taxa and suppressing pathogenic bacteria. Untargeted metabolomics demonstrated that SMEVs reversed DKD-associated metabolic disturbances, characterized by the upregulation of bioactive peptides (eg, Tyr-Leu-His) and unsaturated fatty acids (eg, petroselinic acid), along with the reduction of pro-inflammatory lipids. KEGG enrichment indicated significant modulation of arachidonic acid, linoleic acid, and amino acid metabolism pathways. Spearman correlation analysis further revealed strong associations between key microbial taxa and differential metabolites, suggesting coordinated regulation of gut microbiota and metabolism during SMEV-mediated protection. Conclusion: SMEVs significantly improve the pathological progression of DKD by reshaping the intestinal flora, restoring metabolic homeostasis and inhibiting inflammatory and fibrotic responses, providing an experimental basis for the application of plant-derived extracellular vesicles in kidney diseases. Keywords: diabetic kidney disease, gut microbiota, Salvia miltiorrhiza –derived extracellular vesicles, extracellular vesicles, metabolomics