IL6 and obesity due to melanocortin 4 receptor deficiency: According to recent findings, leptin appears also as an attractive candidate to link obesity, inflammatory mechanisms and osteoarthritis as it has been shown to enhance the production of proinflammatory cytokines and destructive mediators of OA, like NO, IL-6, prostaglandin E2 (PGE2) and MMPs by articular chondrocytes [25].