Exploring causal correlations between inflammatory cytokines and knee osteoarthritis: a two-sample Mendelian...

Area of Science:

• Genetics and Molecular Biology
• Immunology
• Rheumatology

Background:

• Knee osteoarthritis (KOA) is a prevalent condition with complex etiology.
• Inflammatory cytokines, such as interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF-a), are implicated in KOA pathogenesis.
• The precise causal relationships between specific inflammatory cytokines and KOA remain incompletely understood.

Purpose of the Study:

• To investigate the causal relationships between 41 inflammatory cytokines and the risk of developing knee osteoarthritis (KOA).
• To differentiate between upstream and downstream effects of cytokines in KOA etiology using a bidirectional Mendelian randomization approach.

Main Methods:

• A two-sample bidirectional Mendelian randomization (MR) study was conducted.
• Genetic variation data for 41 inflammatory cytokines (n=8293) and knee osteoarthritis (n=403,124) were sourced from European Genome-Wide Association Studies (GWAS).
• Inverse variance weighting (IVW) and various sensitivity analyses were employed to assess causal effects.

Main Results:

• Granulocyte colony-stimulating factor (G-CSF/CSF-3) showed a protective effect, negatively associated with KOA risk (OR: 0.93, 95% CI: 0.89-0.99, P=0.015).
• Macrophage inflammatory protein-1 alpha (MIP-1A/CCL3) was identified as a consequence of KOA (OR: 0.72, 95% CI: 0.54-0.97, P=0.032).
• No significant causal links were found for other tested inflammatory cytokines and KOA.

Conclusions:

• Certain inflammatory cytokines play a role in the etiology of knee osteoarthritis.
• G-CSF (CSF-3) appears to influence KOA development, potentially acting as an upstream factor.
• MIP-1A (CCL-3) is suggested to be a downstream consequence of KOA, indicating its involvement in the disease process.