Microvascular Endothelial Cell-Derived Exosomes Decrease Osteoclastogenesis by Restraining Osteoclast Ferroptosis through the USP13/NRF2/GPX4 Pathway

Exosomes (EXOs), released by diverse cells are implicated in modulating ferroptosis under orthopedic conditions. However, the possible effects of EXOs in osteoclasts and the interaction mechanisms with ferroptosis remain poorly defined. The EXOs were isolated and identified from skeletal muscle microvascular endothelial cells (MMECs). Osteoclasts was generated using RAW264.7 cells stimulated by receptor activator of nuclear factor kappa B ligand (RANKL), followed by EXO treatment. The effects of EXOs and USP13 overexpression during osteoclastogenesis and on osteoclasts ferroptosis were determined. EXO treatment declined the tartrate-resistant acid phosphatase (TRAP)-positive numbers and osteoclast-specific genes expression in RANKL-stimulated RAW264.7 cells. Furthermore, elevated ferrous iron, malondialdehyde (MDA), lactate dehydrogenase (LDH), and reactive oxygen species (ROS) level, downregulated nuclear factor erythroid 2-related factor 2 (NRF2) and glutathione peroxidase 4 (GPX4) expression were found in response to RANKL, which were restricted after EXO treatment. Mechanistically, USP13 was carried out by EXOs and transferred to osteoclasts. USP13 overexpression exerted the suppressive role of RANKL stimulation on osteoclastogenesis and ferroptosis critical hallmarks, while augmented the activation of NRF2/GPX4 pathway. Our research revealed that MMECs-derived exosomal USP13 exhibited the anti-osteoclastogenesis effects by regulating ferroptosis. This may be a useful therapeutic target for the prevention and treatment of osteolytic diseases.