TLR4 Promotes and DAP12 Limits Obesity-Induced Osteoarthritis in Aged Female Mice.

Aging and female sex are the strongest risk factors for nontraumatic osteoarthritis (OA); whereas obesity is a modifiable risk factor accelerating OA. Prior studies indicate that the innate immune receptor toll-like receptor 4 (TLR4) mediates obesity-induced metabolic inflammation and cartilage catabolism via recognition of damage-associated molecular patterns and is increased with aging in OA joints. TLR4 responses are limited by innate immunoreceptor adapter protein DNAX-activating protein of 12kDA (DAP12).