Determination of reference values for cytokines and matrix metalloproteinases in the synovial fluid of horses of different ages

Osteoarthritis (OA) is the most common joint disease in sport horses. Inflammatory and anti-inflammatory cytokines and metalloproteinases (MMPs) play a crucial role in the degradation of the cartilage extracellular matrix. The study of inflammatory molecular biomarkers could be useful in the diagnosis and choice of therapeutic strategies. However, little is known about the normal values of inflammatory biomarkers at different ages. Moreover, early diagnosis of OA is crucial to ensure early treatment in order to prevent chronic damage. The aim of this study was to establish a reference range for values of pro-inflammatory cytokines (IL-1[beta], IL-4, IL-6 and TNF-[alpha]) and MMPs (MMP-2 and MMP-9) in the synovial fluid of horses of different ages. The old horses group presented higher values of IL-4 and TNF-[alpha] than the rest of the groups studied (P