Jiawei Danxuan Koukang and Its Component Kaempferol Alleviate Oral Submucous Fibrosis by Restoring Epithelial-Fibroblast Homeostasis and Suppressing Neutrophil Recruitment via the ANXA1/FPR2 Axis.

Oral submucous fibrosis (OSF) is a betel quid chewing-associated precancerous disorder. Studies have shown that the traditional Chinese medicine Jiawei Danxuan Koukang (JDK) exhibits inhibitory effects on OSF, but its specific mechanisms and molecular targets remain unstated. This study aims to elucidate the pharmacological mechanisms of JDK and its component kaempferol in treating OSF. OSF rat model and in vitro cell models were induced by arecoline. Techniques, including hematoxylin-eosin (HE) staining, Masson staining, western blot, quantitative real-time polymerase chain reaction (qRT-PCR), enzyme-linked immunosorbent assay (ELISA), immunofluorescence (IF) staining, co-immunoprecipitation (Co-IP), and molecular docking were used to evaluate the effects of JDK and kaempferol on OSF pathological damage, Annexin-A1 (ANXA1) expression, neutrophil infiltration, collagen deposition, and fibroblast activation. JDK and kaempferol alleviated pathological damage in the oral mucosa tissues of OSF rats, inhibited collagen deposition and fibroblast activation marker expressions, including fibroblast activation protein (FAP), vimentin (VIM), alpha-smooth muscle actin (α-SMA), and matrix metalloproteinase-1 (MMP1), and improved mouth opening function. Further studies revealed that JDK and kaempferol upregulated ANXA1 expression, thereby suppressing neutrophil recruitment, pro-inflammatory cytokine release, and collagen deposition. In vitro experiments confirmed that kaempferol directly bound to ANXA1 in epithelial cells, enhancing its stability, and interacted with FPR2 signaling in fibroblasts to inhibit their activation, thereby restoring epithelial-fibroblast homeostasis. However, knockdown of ANXA1 reversed these protective effects. JDK and kaempferol attenuated OSF by upregulating the ANXA1/FPR2 axis, inhibiting neutrophil infiltration and fibroblast activation, suggesting ANXA1 as a potential therapeutic target for OSF. To our knowledge, this is the first study to demonstrate that JDK/kaempferol exert anti-fibrotic effects in OSF specifically through the ANXA1/FPR2 axis.