Dietary phytosterol supplementation mitigates renal fibrosis via activating mitophagy and modulating the gut microbiota.

Chronic kidney disease (CKD) poses a significant global health challenge, primarily driven by renal fibrosis, with limited treatment options. Addressing this condition necessitates either targeted medical treatments or dietary interventions. Phytosterols (PS) are cholesterol-like bioactive compounds in various plant-based foods with antioxidant and anti-inflammatory effects. A CKD mouse model was established using folic acid (FA) and treated with dietary supplements of two PS, stigmasterol (Stig) and β-sitosterol (β-Sito). The effects and mechanisms of PS were investigated through biochemical indices, pathology, transcriptomics, and 16S rDNA sequencing. The results indicated that high-dose PS are more effective than low-dose PS and Losartan potassium (LP) in reducing renal fibrosis, restoring function, and modulating oxidative stress and inflammation, with no significant differences between high-dose Stig and β-Sito treatments. Gene Ontology (GO) enrichment analysis revealed that PS were significantly enriched in pathways related to the mitochondrial outer membrane, ubiquitin-protein ligase binding, and other cellular components and molecular processes. PS reduced the expression of TGF-β/Smad and cGAS/Sting1/TBK1 and activated PINK1/Parkin pathway proteins, thereby mitigating renal fibrosis in mice. CKD is often associated with imbalanced gut microbiota and compromised intestinal barriers. Our observations indicated that PS restored the intestinal barrier, altered the composition of the gut microbiota, and improved renal function in CKD mice. The present findings indicate that both Stig and β-Sito activate mitophagy via the PINK1/Parkin pathway and modulate the gut microbiota, thereby alleviating renal fibrosis. The findings provide solid and significant implications for developing effective application of PS supplementation in the management of CKD, presenting novel concepts and approaches for research and clinical treatment.