Inflammatory Mechanisms in the Development of Osteoarthritis

Osteoarthritis was traditionally thought of as a noninflammatory disease, but improved molecular techniques have recognized a significant inflammatory component. An initial joint injury or biomechanical imbalance leads to local tissue damage and inflammation, which is propagated by the innate immune system. The production of damage-associated molecular patterns (DAMPs) results in the activation of immune-modulated mechanisms, leading to the production of catabolic factors that can damage native joint structures such as cartilage. DAMPs may originate from extracellular matrix degradation products, intracellular components of lysed cells, complement, or joint crystals-even plasma proteins can enter through an inflamed synovium and further perpetuate the inflammatory process. Therapeutic interventions have traditionally focused on symptom management; however, there is potential for pharmacologic modification of the disease process in osteoarthritis through novel anti-inflammatory agents.