Huangqi and Danshen improve the chronic nephrotoxicity of cyclosporin A by regulating lipid metabolism.

Background: The clinical application of cyclosporine A (CsA) is limited due to nephrotoxicity. Lipid metabolism disorders play important roles in renal injury, but their role in CsA nephrotoxicity is not yet clear. Huangqi (Astragalus mongholicus Bunge) and Danshen (Salvia miltiorrhiza Bunge) (HD) play roles in ameliorating the nephrotoxicity of CsA, but their mechanisms still need to be fully clarified.

Objective: This study innovatively aimed to analyse the coexpression of renal proteins and serum metabolites for the identification of key pathways and targets. This study provides novel insight into the mechanism by which HD ameliorates CsA-induced nephrotoxicity.

Methods: We utilized HD to intervene in both in vivo and in vitro nephrotoxicity models induced by CsA. For the in vivo experiments, we constructed a coexpression network of renal proteins and serum metabolites, which was used to screen for key pathways. To validate these findings, we knocked down key proteins in vivo. For the in vitro studies, we employed MTT, Transwell, flow cytometry, and immunofluorescence assays to monitor the epithelial-mesenchymal transition (EMT) of HK-2 cells. Additionally, we used electron microscopy and Seahorse assays to examine the effects of HD on mitochondrial structure and function. Furthermore, we overexpressed Ppara to further confirm the mechanism by which HD improves renal function.

Results: HD can improve renal pathological damage and function; regulate blood lipids, inflammation and oxidative stress indicators; and reduce apoptosis in renal tissues. Joint protein and metabolomics analyses revealed that two lipid metabolism-related pathways (the PPAR signalling pathway and linoleic acid metabolism pathway) were coenriched, involving six differential proteins (Cyp2e1, Cyp4a10, Gk, Lpl, Ppara, and Pck1) and two differentially abundant metabolites (alpha-Dimorphecolic acid and 12,13-EpOME). Western blot was used to verify differentially expressed proteins. HD improved mitochondrial damage and lipid accumulation, as demonstrated by transmission electron microscopy (TEM) analysis and Oil Red O staining. Knockdown of the key protein Ppara affected the expression of ACOX1 and exacerbated RF. In vitro verification demonstrated that HD significantly inhibited CsA-induced EMT in HK-2 cells and improved mitochondrial structure and function. Ppara overexpression promoted HD-mediated regulation of mitochondrial function, reduced apoptosis, and improved HK-2 RF.

Conclusion: HD can ameliorate CsA nephrotoxicity through renal protein-serum metabolism coexpression, the PPAR signalling pathway, and linoleic acid metabolism. HD-induced upregulation of Ppara to regulate lipid metabolism, improve mitochondrial function and reduce apoptosis are important mechanisms. The Ppara/ACOX1/TGF-β1 axis may play an important role in this process. These findings offer potential targets for the future development of therapeutic strategies and novel drugs.