TWEAK promotes osteoclastogenesis in rheumatoid arthritis

Area of Science:

• Immunology
• Rheumatology
• Cell Biology

Background:

• Rheumatoid arthritis (RA) causes functional disability through bone destruction.
• Osteoclasts, regulated by cytokines like RANKL, are key mediators of bone resorption in RA.
• Tumor necrosis factor-like weak inducer of apoptosis (TWEAK) is a potential factor in RA pathogenesis.

Purpose of the Study:

• To investigate the osteoclastogenic activity of TWEAK in rheumatoid arthritis.
• To assess TWEAK levels and function in RA patients and relevant animal models.
• To explore TWEAK's role in RANKL-dependent and independent osteoclastogenesis.

Main Methods:

• Quantified TWEAK levels in RA patient samples (synovium, synovial fluid, serum) and mouse models (CIA, IL-1RaKO).
• Assessed TWEAK's effect on RANKL expression in joint cells, splenocytes, and synoviocytes.
• Evaluated TWEAK's impact on osteoclastogenesis in vitro, with and without RANKL-providing cells.
• Utilized fibroblast growth factor-inducible 14-Fc to inhibit TWEAK-mediated osteoclastogenesis.

Main Results:

• TWEAK levels were elevated in RA patients and in mouse models of arthritis.
• TWEAK stimulated RANKL expression in various cell types relevant to RA.
• TWEAK directly enhanced osteoclast formation in vitro, independent of RANKL-expressing cells.
• Fibroblast growth factor-inducible 14-Fc treatment inhibited TWEAK-induced osteoclastogenesis.

Conclusions:

• TWEAK plays a significant role in promoting osteoclastogenesis in rheumatoid arthritis.
• Elevated TWEAK levels contribute to bone destruction in RA.
• Targeting TWEAK represents a promising therapeutic strategy for preventing bone loss in RA.