Syndecan-1 regulates lipid metabolism and mitigates fibrosis during the transition from acute kidney injury to chronic kidney disease

Background

The transition from acute kidney injury (AKI) to chronic kidney disease (CKD) is characterized by persistent renal fibrosis, in which abnormal lipid metabolism plays a crucial role. Syndecan-1 (SDC-1) has been implicated in various tissue remodeling processes; however, its role in lipid metabolism and fibrosis during the progression from AKI to CKD is not well understood.

Methods

This study used a murine model of unilateral ischemia-reperfusion-induced AKI-to-CKD progression for in vivo analysis and employed transforming growth factor-beta (TGF-β)-induced fibrosis in Human Kidney-2 cells and primary mouse tubular epithelial cells for in vitro studies. The tubule-specific knockout and overexpression of SDC-1 mice were utilized to investigate kidney fibrosis and lipid metabolism.

Results

Following unilateral ischemia-reperfusion and TGF-β stimulation, SDC-1 expression was significantly reduced, exacerbating renal fibrosis. Notably, SDC-1 deficiency led to lipid accumulation in the kidneys, while its overexpression alleviated lipid overload and improved metabolic parameters. Furthermore, SDC-1 played a crucial role in regulating fatty acid-binding protein 7 (FABP7), and its absence resulted in increased FABP7 levels. Inhibition of FABP7 not only reduced fibrosis but also restored carnitine palmitoyltransferase 1α expression, which suggests that the SDC-1/FABP7 axis is critical for maintaining lipid homeostasis and mitigating fibrosis in the kidney.

Conclusion

These findings underscore the importance of SDC-1 in lipid metabolism and suggest that targeting lipid metabolic pathways may represent therapeutic strategies that can slow the progression of AKI to CKD.