# Kaempferol Alleviates Glucocorticoid-Induced Osteonecrosis of the Femoral Head by Modulating Macrophage M1/M2 Polarization Through RhoA/ROCK-Mediated Mitophagy Activation

## TL;DR

Kaempferol helps treat a bone disease caused by steroids by shifting immune cells to a healing state through a specific biological pathway.

## Contribution

Kaempferol's novel mechanism in treating glucocorticoid-induced osteonecrosis via RhoA/ROCK-mediated mitophagy activation is revealed.

## Key findings

- Kaempferol increases M2 macrophages and decreases M1 macrophages in vitro.
- Kaempferol-treated macrophage medium enhances osteogenic and angiogenic activity in cells.
- Kaempferol activates mitophagy by inhibiting the RhoA/ROCK pathway in macrophages.

## Abstract

Background/Objectives: Dysregulated macrophage M1/M2 polarization is implicated in glucocorticoid-induced osteonecrosis of the femoral head (GONFH). Reprogramming M1 to M2 macrophages represents a potential therapeutic strategy. Kaempferol (KPF), a natural flavonoid with anti-inflammatory properties, may offer benefits, but its mechanism in GONFH is unknown. Purpose: This study aims to explore the therapeutic impact of KPF on GONFH and the mechanisms involved. Methods: In vitro, macrophage viability (CCK-8 assay) and polarization (RT-qPCR, flow cytometry) were assessed. Conditioned medium from KPF-treated macrophages was co-cultured with BMSCs and HUVECs to evaluate osteogenic and angiogenic effects. Mechanisms were analyzed using Western blot, immunofluorescence, and flow cytometry. A rat GONFH model validated in vivo effects. Results: In vitro experiments revealed that KPF significantly augmented the ratio of M2 macrophages while concurrently diminishing the proportion of M1 macrophages. The conditioned medium derived from macrophages treated with KPF markedly improved the osteogenic and angiogenic capabilities of BMSCs and HUVECs. Immunofluorescence staining and Western blot revealed that KPF regulated macrophage polarization by enhancing mitophagy, which was reversed by the addition of a mitophagy inhibitor. Further experiments confirmed that KPF activated mitophagy by inhibiting the RhoA/ROCK signaling pathway. In vivo, KPF increased the proportion of M2 macrophages and promoted the expression of osteogenic and angiogenic markers. Conclusions: In conclusion, our study demonstrates that KPF alleviates GONFH by modulating macrophage M1/M2 polarization through RhoA/ROCK-mediated mitophagy activation. These findings provide novel insights into the treatment of GONFH.