ATF3 triggers M2 macrophage polarization to protect against pulp inflammation through WNT4 regulation

Pulpitis is a common inflammatory oral disease that can lead to pulp necrosis. The aim of this study is to investigate the expression and regulatory mechanisms of ATF3, a potential therapeutic marker, in pulpitis. A mouse pulpitis model with different degrees of inflammation is established, and the expression of ATF3 in pulpitis is explored. The histological features of healthy pulp and pulpitis are analyzed by HE staining, and classical inflammatory factors are detected by immunohistochemistry (IHC). In an <i>in vitro</i> study, we investigate the role of ATF3 in the regulation of WNT4 transcription and explore the effects of the ATF3/WNT4 axis on the polarization of RAW264.7 macrophages, the inflammatory response and the osteogenic differentiation of human dental pulp stem/stromal cells (hDPSCs). Our results show that ATF3 is expressed at low levels in inflamed pulp tissues; overexpression of ATF3 reduces the area of pulp necrosis, decreases the level of pro-inflammatory factors, and promotes macrophage polarization toward the M2 type. Furthermore, we reveal that ATF3 binds to the WNT4 promoter region and positively regulates the expression of WNT4 and that ATF3 downregulates M1 markers and increases the expression of M2 markers by regulating WNT4 expression. In addition, ATF3 promotes the osteogenic differentiation of dental pulp stem cells. In summary, this study reveals that ATF3 promotes M2 macrophage polarization by regulating WNT4, which in turn inhibits pulpal inflammatory responses and promotes the osteogenic differentiation of dental pulp stem cells. These findings suggest that ATF3 may be a potential target for pulpitis treatment.