Cannabinoid receptors expression positively correlated with synovitis in horses with spontaneous osteoarthritis

Purpose: Osteoarthritis (OA) is a major cause of disabling pain in all species and palliative therapy with anti-inflammatory molecules common but has many associated undesirable side-effects. There increasing interest the use cannabinoids for OA therapy. The horse suitable large animal model cartilage studies information lacking concerning endocannabinoid system equine joint.Our objectives are (1) to investigate cannabinoid receptor (CB1 & CB2) expression pattern synovium healthy joints (2) study relationship between expression, synovitis scores. Methods: Tissue specimens were available repository. metacarpophalangeal (n=25) dissected, macroscopic articular lesions scored (OA score). Synovial membrane (n=45; 2 anatomical sites) harvested, fixed, sectioned, stained H&E histologically synovitis. Synovium immunohistochemical staining employing CB1 CB2 antibodies was performed on each section controls. All sections digitalized. regions (ROIs; n =5) randomly selected positive cell immunoreactive by blinded observers (Figure 1). interobserver agreement calculated ICC. relationships CB2, scores interrogated mixed linear model. Results: ICCs 84.6% 92.9% respectively. expressed studied (40/40) both whereas identified 93% (40/43) 95% (41/43) observers. Significant interactions found (p=0.038) p=0.027) score. However, score negatively correlated (p=0.03). A similar trend observed (p=0.64) 2). Conclusions: Equine synovial intimal cells constitutively express revealing functional joint. correlation holds great promise treating osteoarthritic targeting inflammation cannabinoids.View Large Image Figure ViewerDownload Hi-res image Download (PPT)