Curcumin inhibits angiogenesis in endometriosis by regulating miR-495-3p expression in M2 macrophage-derived sEVs

Background Endometriosis (EMs) is a common and challenging condition affecting women of reproductive age. Local vascularisation of ectopic lesions is a key driver of disease progression, and effective anti-angiogenic therapies remain limited. Curcumin has shown therapeutic efficacy against endometriotic lesions; however, the mechanism underlying its inhibition of angiogenesis remains unclear. Methods A mouse EMs model was established to evaluate the in vivo effects of curcumin on ectopic lesion formation and local angiogenesis. In vitro experiments using human umbilical vein endothelial cells (HUVECs) were performed to determine the optimal inhibitory concentration of curcumin. Small extracellular vesicles (sEVs) were isolated and characterised from human peritoneal macrophages and from the THP-1 and RAW264.7 cell lines. A co-culture system was employed to assess whether curcumin regulates macrophage polarisation and thereby alters the effects of macrophage-derived sEVs on HUVEC angiogenesis. Differentially expressed miRNAs were identified by high-throughput miRNA sequencing and bioinformatic analysis, followed by functional validation of key candidates. Results In vivo, curcumin administration significantly reduced the size, volume, and adhesion of endometriotic lesions and suppressed local angiogenesis. In vitro, direct inhibition of HUVEC angiogenesis required 30 μM curcumin, whereas a lower concentration (10 μM) effectively modulated macrophage-derived sEVs to produce comparable anti-angiogenic effects. This treatment significantly reversed the pro-angiogenic activity of sEVs derived from EMs patients. Mechanistically, treatment with 10 μM curcumin was associated with a shift towards an M1-like macrophage phenotype and altered sEVs' activity. This change altered sEVs' cargo and subsequently inhibited HUVEC tube formation. miRNA sequencing identified miR-495-3p as a key mediator. Curcumin treatment significantly increased miR-495-3p levels in macrophage-derived sEVs. Functional assays demonstrated that inhibition of miR-495-3p partially restored HUVEC proliferation, migration, and tube formation suppressed by sEVs from curcumin-treated macrophages. While bioinformatic prediction and dual-luciferase reporter analysis identified BMI1 as a direct target and potential downstream effector of miR-495-3p. Conclusions Curcumin suppresses EMs progression by regulating macrophage polarisation and modifying sEVs' miRNA expression profiles. Its anti-angiogenic effect is mediated, at least in part, by upregulation of macrophage-derived sEVs' miR-495-3p. BMI1 was a direct target and potential downstream effector of miR-495-3p. These findings provide molecular evidence for the anti-angiogenic activity of curcumin and identify the macrophage–sEV–angiogenesis axis as a potential therapeutic target for EMs.