Imbalance of renin-angiotensin system in calcium oxalate crystals-induced renal oxidative stress and autophagy.

BACKGROUND

Calcium oxalate (CaOx) stones are the most prevalent urological calculi with high incidence and recurrence. Effective preventive drugs remain lacking because of unclear pathogenesis. Although the imbalance of the dual renin-angiotensin system (RAS) axes is closely linked to oxidative stress and autophagy, its role in CaOx stone formation remains undefined.

METHODS

In vitro, human renal tubular epithelial cells were stimulated with CaOx crystals, with siRNA-mediated AT1R or MasR knockdown or pretreatment with Ang Ⅱ, Ang-(1-7), antioxidant Nacetylcysteine (NAC) or autophagy inhibitor 3-methyladenine (3-MA). RAS components, oxidative stress markers, autophagy-related proteins, stone-related proteins and crystal adhesion were detected. In vivo, a mouse CaOx stone model was induced by intraperitoneal glyoxylic acid injection, with adeno-associated virus-mediated AT1R or MasR knockdown. The above indicators and renal crystal deposition were evaluated.

RESULTS

CaOx crystals significantly activated the ACE/Ang Ⅱ/AT1R axis and inhibited the ACE2/Ang-(1-7)/MasR axis in vitro and in vivo, causing intrarenal RAS imbalance. CaOx crystals induced NOX2/4-mediated oxidative stress and AMPK/mTOR-dependent autophagy, which formed a mutually reinforcing loop to upregulate stone-related proteins (OPN, CD44, MCP-1). Activating the ACE/Ang Ⅱ/AT1R axis with Ang Ⅱ exacerbated these pathological changes, while AT1R knockdown alleviated them; conversely, activating the ACE2/Ang-(1-7)/MasR axis with Ang-(1-7) exerted protective effects, whereas MasR knockdown worsened injury. In vivo findings corroborated these results.

CONCLUSION

The ACE/Ang Ⅱ/AT1R axis plays a pathogenic role in CaOx stone formation, whereas the ACE2/Ang-(1-7)/MasR axis exerts a protective effect. Restoring this intrarenal RAS balance represents a promising therapeutic strategy against CaOx stones.