Autoantibodies targeting malondialdehyde-modifications in rheumatoid arthritis regulate osteoclasts via inducing...

Area of Science:

• Immunology
• Rheumatology
• Molecular Biology
• Metabolic pathways

Background:

• Rheumatoid arthritis (RA) involves autoantibodies against post-translationally modified proteins.
• The precise molecular mechanisms by which these autoantibodies contribute to RA pathogenesis, particularly bone erosion, remain largely unknown.

Purpose of the Study:

• To elucidate the molecular pathways induced by anti-malondialdehyde (MDA) modified protein antibodies in rheumatoid arthritis (RA).
• To investigate the role of these antibodies in osteoclast differentiation and bone erosion.

Main Methods:

• Isolation of anti-MDA antibodies from synovial B cells of RA patients.
• Assessment of osteoclast stimulatory potential and in vivo bone erosion.
• Analysis of metabolic pathways including glycolysis, oxidative phosphorylation, and lipid biosynthesis in developing osteoclasts.
• Investigation of FcγRI, HIF-1α, MYC, citrate production, GPD1, and GPAT2 gene expression.

Main Results:

• Anti-MDA antibodies from RA patients demonstrated robust osteoclast stimulatory potential and induced bone erosion in vivo.
• These antibodies enhanced glycolysis and subsequently oxidative phosphorylation in developing osteoclasts via FcγRI, HIF-1α, and MYC.
• Osteoclast development was supported by enhanced phosphoglyceride and triacylglyceride biosynthesis, modulated by anti-MDA through citrate production and specific gene expression (GPD1, GPAT2).

Conclusions:

• Novel metabolic pathways are crucial for osteoclast differentiation in RA.
• Anti-MDA antibodies target these metabolic pathways, accelerating bone erosion in rheumatoid arthritis.
• This study identifies key molecular mechanisms linking humoral autoimmunity to bone destruction in RA.