Tartrate-Resistant Acid Phosphatase 5 (TRAP/ACP5) aggravates atherosclerosis by regulating macrophage polarization and promoting ferroptosis

Atherosclerosis is a lipid-driven chronic inflammatory process, in which the functional status of macrophages significantly influences its initiation, progression, and eventual outcomes. Tartrate-Resistant Acid Phosphatase 5 (ACP5) has been shown to be highly expressed in various cancers and serves as a serum biomarker for extensive bone metastasis and poor prognosis. However, its role and underlying mechanisms in atherosclerosis remain largely unknown. In this study, we found that high-fat diet-fed Apoe^-/- mice exhibit significantly elevated ACP5 expression in aorta tissue and macrophages within the aortic root. Pharmacological inhibition of ACP5 with AubipyOMe markedly reduced atherosclerotic plaque area and decreased the proportion of M1-type macrophages within the plaques. Conversely, macrophage-specific overexpression of ACP5 promoted plaque enlargement and enhanced M1 macrophage infiltration. In vitro, knockdown of ACP5 suppressed the polarization of bone marrow-derived macrophages (BMDMs) toward the M1 phenotype, while its overexpression inhibited M2 polarization. Furthermore, ox-LDL significantly upregulated ACP5 expression in RAW264.7 macrophages, and ACP5 was co-localized with phosphorylated STAT3 in these cells. This ox-LDL-induced upregulation of ACP5 was effectively reversed by the JAK2 inhibitor fedratinib. Further analysis by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and co-immunoprecipitation (co-IP) identified an interaction between ACP5 and VDAC3. Overexpression of ACP5 decreased VDAC3 phosphorylation, whereas ACP5 knockdown increased it. In vitro functional assays confirmed that ACP5 knockdown in RAW264.7 cells enhanced cell viability, elevated glutathione (GSH) levels, and reduced malondialdehyde (MDA), Fe²⁺, and Lipid peroxides levels, whereas ACP5 overexpression produced the opposite effects. Using the Cre/loxP system, we generated macrophage-specific ACP5-knockout Apoe^-/- mice. Conditional ablation of ACP5 significantly reduced aortic plaque area, decreased M1 macrophage proportion in peritoneal lavage fluid, diminished 4-HNE expression in the aortic root, reduced numbers of atrophic mitochondria, and increased aortic GPX4 expression. In conclusion, ACP5 exacerbates atherosclerosis by modulating macrophage polarization and promoting macrophage ferroptosis.