Metformin protects against cyclophosphamide-induced ovarian fibrosis by MIF/CD74-mediated macrophage polarization.

BACKGROUND: Cyclophosphamide (CTX) -induced ovarian fibrosis is involved in premature ovarian failure (POF). While metformin has demonstrated anti-fibrotic properties, the mechanism by which it regulates fibroblast activation, the primary effector cells in fibrosis, remains unclear in POF.

METHODS: The therapeutic effects of metformin were investigated in CTX-treated mice and further explored its interaction with macrophage-fibroblast crosstalk using an in vitro co-culture system.

RESULTS: RNA sequencing revealed that metformin suppressed the MIF/CD74 signaling pathway, which was significantly activated by CTX in ovarian tissues. In vitro, CTX increased the CD86+/CD206 + macrophage ratio via NF-κB pathway activation, indicating altered macrophage polarization. Metformin or the MIF inhibitor ISO-1 reversed this polarization imbalance, thereby attenuating fibroblast activation and extracellular matrix (ECM) production in co-culture models. Additionally, CD74 knockdown in fibroblasts downregulated ECM-related genes and inhibited MAPK/JNK signaling, whereas CD74 overexpression exacerbated the fibrotic responses.

CONCLUSION: These findings highlight a novel mechanism by which metformin alleviates CTX-induced ovarian fibrosis by targeting the MIF/CD74 axis to reprogram macrophage-fibroblast communication, suggesting metformin as a protective adjuvant to improve ovarian health during chemotherapy.