Macrophage-derived migrasomes promote fibrotic remodeling in endometriosis with TGF-β/Smad signaling activation

Abstract Background Progressive fibrosis of ectopic lesions is a major pathological feature of endometriosis, contributing to treatment resistance and disease recurrence. However, the mechanisms driving this fibrotic process remain incompletely understood. Methods A murine model of endometriosis was established by transplanting endometrial tissue fragments into the peritoneal cavity of C57BL/6 mice. Macrophage-derived migrasomes were isolated from cultured RAW264.7 cells, characterized by scanning electron microscopy and Western blot, and administered intraperitoneally to endometriosis-bearing mice. Fibrotic changes were assessed by histology, immunofluorescence, and Western blot analysis of signaling pathways and epithelial-mesenchymal transition (EMT) markers. Cytokine levels were measured by enzyme-linked immunosorbent assay (ELISA). Results Exogenously administered macrophage-derived migrasomes accumulated at ectopic lesion sites and markedly aggravated fibrotic remodeling. Migrasome-treated lesions exhibited cyst-wall thickening, increased stromal cellularity, and extensive collagen deposition. At the molecular level, migrasome treatment was associated with activation of the transforming growth factor-beta (TGF-β)/Smad pathway in ectopic lesions, as indicated by increased phosphorylation of Smad2 and Smad3 without significant changes in total Smad2/3 levels. This was accompanied by increased α-smooth muscle actin and vimentin expression together with reduced cytokeratin 18 (CK18) and E-cadherin expression, consistent with EMT-like phenotypic reprogramming. In parallel, TGF-β1 and VEGF levels were elevated, whereas MMP9 was reduced, collectively supporting a pro-fibrotic microenvironment. Conclusions These findings identify macrophage-derived migrasomes as previously unrecognized promoters of fibrotic remodeling in endometriosis and support a role for migrasome-associated signaling in lesion progression. This work provides new insight into the pathogenesis of endometriosis-associated fibrosis and highlights migrasomes as a potential target for future anti-fibrotic intervention.