Synovial fluid alpha-2-macroglobulin, gelsolin and lubricin distinguish between osteoarthritic and healthy equine joints.
Authors: Secor, Womack, Ysebaert, Colville, Reesink
Journal: Equine veterinary journal
Summary
# Editorial Summary: Synovial Fluid Biomarkers for Equine Joint Disease Researchers used liquid chromatography-tandem mass spectrometry to identify proteins in synovial fluid that distinguish osteoarthritic from healthy carpal joints in horses, comparing 8 OA and 8 healthy joints initially via untargeted proteomics, then validating findings across a larger cohort (58 OA, 25 healthy joints). Of 119 proteins detected, alpha-2-macroglobulin and pregnancy zone protein showed the strongest upregulation in diseased joints, whilst gelsolin concentrations (normalised to total protein) were substantially lower in OA samples (0.48 versus 0.89 µg/mL/mg in healthy joints) and lubricin markedly elevated (27.98 versus 6.77 µg/mL/mg). When combined in multivariate modelling with prostaglandin E2 levels, these three markers outperformed single-protein assessments for differentiating joint health status. The findings suggest that gelsolin, lubricin and alpha-2-macroglobulin warrant further investigation as potential diagnostic biomarkers for early carpal osteoarthritis, offering equine veterinarians a more sophisticated tool for joint assessment alongside conventional imaging and clinical examination; however, the authors acknowledge limitations including tissue sampling from post-euthanasia controls and the need to validate these markers across other anatomical sites and disease stages.
Read the full abstract on PubMed
Practical Takeaways
- •Synovial fluid analysis using a combination of gelsolin, lubricin, and PGE2 measurements may provide improved diagnostic accuracy for early carpal osteoarthritis compared to single biomarkers
- •Alpha-2-macroglobulin and pregnancy zone protein warrant further investigation as potential diagnostic or prognostic markers for equine joint disease
- •These synovial fluid biomarkers could help clinicians better distinguish mild-to-moderate carpal disease from normal joint pathology, potentially improving treatment decision-making
Key Findings
- •Of 119 proteins identified in synovial fluid, 14 were increased and 10 decreased in osteoarthritic joints compared to healthy joints
- •Alpha-2-macroglobulin and pregnancy zone protein were among the most upregulated proteins in OA joints
- •Gelsolin/total protein ratio was significantly decreased in OA joints (median 0.48 vs 0.89 μg/mL/mg in healthy joints)
- •Lubricin/total protein ratio was significantly increased in OA joints (27.98 vs 6.77 μg/mL/mg in healthy joints)
- •Multivariate modeling combining gelsolin/TP, lubricin/TP, and PGE2 was superior to individual markers for distinguishing OA from healthy joints