Mechanical stress and nitric oxide influence leukotriene production in cartilage

Nitric oxide (NO) and leukotrienes regulate a variety of processes in joint tissues and are frequently elevated in arthritis. Mechanical stress can induce biochemical and functional changes in cartilage that may influence mediator production. To investigate the relationship between mechanical stress and the production of leukotriene B(4) (LTB(4)) and NO, explants of porcine articular cartilage were subjected to mechanical compression for 1 h followed by 23 h recovery in the presence or absence of the NOS2 inhibitor 1400W. Dynamic compression significantly increased LTB(4) and LOX protein production in the presence of 1400W. The induced LTB(4) was functional as evidenced by its ability to promote chemotaxis of RBL-2H3 cells expressing the LTB(4) receptor. Increased LOX protein but not LTB(4) occurred in response to compression alone. These findings provide a direct link between mechanical stress and inflammation in cartilage and may have implications in the pathogenesis and treatment of arthritis.