Cytokine and chemokine gene expression of IL-1β stimulated equine articular chondrocytes

Objective-To evaluate mRNA expression of several proinflammatory and anti-inflammatory cytokines and chemokines in equine unstimulated and interleukin-1 beta (IL-1 beta)-stimulated chondrocytes. Study Design-In vitro experiment using equine chondrocyte cultures. Sample Population-Whole articular cartilage from metacarpophalangeal joints (n-5 horses-, 10 fetlocks). Methods-Chondrocyte monolayer cultures were established from digested adult equine articular cartilage and stimulated with 5 ng/mL of recombinant human IL-1 beta. RNA was extracted from the cells 24 hours after stimulation. IL-1 beta, IL-4, IL-6, IL-8, tumor necrosis factor-alpha (TNF-alpha), and ubiquitin (house keeping gene) mRNA expression were investigated by real-time RT-PCR. Results-IL-1 beta, IL-6, and IL-8 mRNA were expressed in unstimulated chondrocytes from macroscopically normal joints and were significantly up-regulated after stimulation (5/5 horses). IL-4 mRNA was not detected in any samples (015 horses). TNF-a mRNA, by comparison, was expressed in 2/5 unstimulated samples and in all stimulated samples but a considerable sample variation in response to IL- I P stimulation was observed. Conclusions-Equine chondrocytes express mRNA for several proinflammatory cytokines and chemokines and IL- I P modulates their expression. Clinical Relevance-Chondrocytes express proinflammatory cytokines and chemokines capable of modulating a local inflammatory cascade in articular cartilage, which could potentially lead to focal degradation and osteoarthritis. (c) Copyright 2007 by The American College of Veterinary, Surgeons