Tectorigenin could alleviate SA-AKI via reducing M1-like polarization of macrophages through KLF4/NF-κB pathway.

BACKGROUND

Tectorigenin, an isoflavone compound, exhibits anti-inflammatory, antibacterial, and anti-tumor properties. However, its effects on sepsis-associated acute kidney injury (SA-AKI) and its underlying mechanisms have not been explored. This study aims to investigate the therapeutic potential and mechanisms of tectorigenin in SA-AKI.

METHOD: In this study, we utilized a LPS-induced SA-AKI mouse model and RAW264.7 and peritoneal primary macrophages to investigate the therapeutic effects of tectorigenin and explore the underlying mechanism. Flow cytometry assessed M1-like polarization in the models. Pro-inflammatory (M1-like) polarization of peritoneal primary macrophages was induced in vitro, which were treated by tectorigenin and renal injury was examined through renal parenchymal injection of macrophages, followed by HE staining and transmission electron microscopy. Analysis of the single-cell sequencing database (GSE 151658) indicated downregulation of KLF4 in renal macrophages of SA-AKI mice.RAW264.7 and HK-2 cells were co-cultured in Transwell. Besides, renal tubular epithelial cells were separated and detected inflammation-related factors.

RESULT: In the LPS-induced SA-AKI mouse model, tectorigenin alleviated kidney injury and significantly inhibited M1-like macrophage polarization. In the renal parenchymal injection model, macrophages treated with tectorigenin displayed less kidney damage than those injected with LPS. Single-cell sequencing revealed reduced KLF4 expression in M1-like macrophages in the SA-AKI model, contributing to NF-κB pathway activation. In LPS-stimulated RAW264.7, tectorigenin elevated KLF4 expression, reduced nuclear translocation of p65, inhibited NF-κB activation, and reduced M1-like polarization. Knockdown of KLF4 via siRNA transfection abolished tectorigenin's effect on M1-like polarization. Furthermore, inflammatory activation of HK-2 cells co-cultured with tectorigenin-treated macrophages was lower compared to LPS-treated counterparts. Tectorigenin could reduce the activation of TECs inflammatory signaling pathways in SA-AKI mice.

CONCLUSION

Tectorigenin downregulates M1-like macrophage polarization through the KLF4/NF-κB pathway, reducing inflammation in renal tubular epithelial cells and alleviating SA-AKI.