ZEB1 maintains mitochondrial fission and macrophage efferocytosis by restraining MFN2, thereby limiting inflammation and improving tendon‑bone healing

Excessive inflammation and scar formation at the tendon‑bone interface (TBI) hinder effective healing. Macrophage efferocytosis is critical for resolving inflammation, yet its regulatory mechanisms in TBI healing remain unclear. The present study investigated the role of zinc finger E‑box binding homeobox 1 (ZEB1) in macrophage efferocytosis and rotator cuff repair. Zeb1 knockdown in rats was achieved using short hairpin RNA (shRNA). Bone marrow‑derived macrophages co‑cultured with apoptotic Jurkat cells were used to evaluate efferocytosis efficiency. Mechanistically, ZEB1 was demonstrated to function as a critical regulator of mitochondrial dynamics by transcriptionally repressing Mitofusin‑2 (MFN2), thereby maintaining the mitochondrial fission necessary for efficient efferocytosis. ZEB1‑knockdown relieved MFN2 suppression, leading to excessive mitochondrial fusion and a subsequent decrease in apoptotic cell clearance. In vivo, ZEB1 deficiency resulted in the accumulation of secondary necrotic cells, aggravated the inflammatory microenvironment (increased M1/decreased M2 polarization), and impaired histological and biomechanical healing of the tendon‑bone interface. These findings indicate a novel ZEB1/MFN2/mitochondrial fission axis that governs macrophage efferocytosis. Targeting this axis to restore the immune microenvironment offers a potential therapeutic strategy for improving tendon‑bone healing.