Suyin Detoxification Granule alleviates trimethylamine N-oxide–induced tubular ferroptosis and renal fibrosis to prevent chronic kidney disease progression

Background

Trimethylamine N-oxide (TMAO), a gut microbiota metabolite, is a risk factor for chronic kidney disease (CKD) progression. Suyin Detoxification Granule (SDG) is a traditional Chinese medicine preparation that has been proven to significantly reduce renal function damage and serum TMAO levels in patients with CKD. However, its specific mechanism remains unclear.

Purpose

This study investigated the role of TMAO-induced ferroptosis in CKD, and further explored the mechanism of SDG in improving TMAO-induced kidney injury.

Methods

A TMAO renal tubular epithelial cell injury model was constructed in vitro. After using freeze-dried powder of Suyin Detoxification Prescription (SDP), proteomic analysis, Western blotting, ferroptosis phenotype-related detection, and ELISA were performed to explore its mechanism. In vivo, a adenine-induced CKD model was established, with or without a high-choline diet to observe the impact of TMAO on CKD, and SDG or 3,3-Dimethyl-1-butanol (DMB, a TMAO inhibitor) was used for intervention. The composition of gut microbiota was analyzed using 16SrRNA sequencing, and the effect of SDG on gut-derived TMAO-induced kidney injury under the background of CKD was evaluated by pathological staining, immunoblotting, immunohistochemistry, and fluorescence staining.

Results

In vitro, TMAO could induce ferroptosis and secrete profibrotic factors in NRK-52E cells. SDP could inhibit TMAO-induced ferroptosis and reduce the secretion of profibrotic factors. The amelioration of ferroptosis by SDP was also verified in RSL3-induced cells. In vivo, our results demonstrated that gut-derived TMAO could promote CKD progression by inducing tubular ferroptosis, profibrotic factors expression and renal fibrosis. In addition, we illustrated that SDG might reduce circulating TMAO levels by down-regulating the gut microbiota related to TMAO (including Muribaculaceae, Bacteroides and Ruminococcaceae_UCG-010). Furthermore, SDG could prevent CKD progression by reducing TMAO-induced renal damage.

Conclusion

SDG reduced circulating TMAO levels by regulating gut microbiota and inhibited TMAO-induced renal tubular ferroptosis, profibrotic factors secretion, and renal fibrosis to prevent CKD progression.