MFG-E8 regulated by miR-99b-5p protects against osteoarthritis by targeting chondrocyte senescence and macrophage...

Area of Science:

• Biochemistry
• Immunology
• Orthopedics

Background:

• Milk fat globule-epidermal growth factor 8 (MFG-E8) is crucial for efferocytosis but its role in osteoarthritis (OA) is unknown.
• MFG-E8 acts as a bridging molecule between apoptotic cells and phagocytes, influencing inflammation and tissue repair.

Purpose of the Study:

• To investigate the role of MFG-E8 in the pathogenesis of OA.
• To explore MFG-E8's impact on chondrocyte senescence and macrophage polarization in OA.
• To evaluate MFG-E8 as a potential therapeutic target for OA.

Main Methods:

• Downregulation of MFG-E8 in OA patients and DMM-induced OA mouse models.
• Assessment of OA progression in MFG-E8 deficient mice and effects of recombinant MFG-E8 (rmMFG-E8) administration.
• Analysis of chondrocyte senescence, macrophage polarization (M1/M2), and NF-κB signaling.
• Investigation of miR-99b-5p regulation of MFG-E8.

Main Results:

• MFG-E8 expression was decreased in OA cartilage and serum.
• MFG-E8 deficiency exacerbated OA, causing cartilage damage, synovial hyperplasia, and osteophytes.
• Intra-articular rmMFG-E8 administration ameliorated OA.
• MFG-E8 suppressed chondrocyte senescence and promoted M2 macrophage polarization.
• miR-99b-5p inhibited MFG-E8, exacerbating OA via NF-κB activation.

Conclusions:

• MFG-E8 plays a critical role in regulating chondrocyte senescence and macrophage polarization in OA.
• MFG-E8 deficiency contributes to OA pathogenesis.
• Intra-articular MFG-E8 injection is a potential therapeutic strategy for OA.