A 25-year-old woman develops a sore, red, hot, swollen left knee. She has no history of trauma and no familial history of joint disease. Fluid aspirated from the joint space shows an abundance of segmented neutrophils. Aspirin is effective in relieving symptoms of acute inflammation in the patient because it inhibits which of the following enzymes?
Cyclooxygenase. Arachidonic acid is metabolized by cyclooxygenases (COX-1, COX-2) and lipoxygenases (5-LOX) to generate prostanoids and leukotrienes, respectively. The early inflammatory prostanoid response is COX-1 dependent. COX-2 becomes the major source of prostanoids as inflammation progresses. Inhibition of COX is one mechanism by which nonsteroidal anti-inflammatory drugs (NSAIDs), including aspirin, indomethacin, and ibuprofen, exert their potent analgesic and anti-inflammatory effects. NSAIDs block COX-2-induced formation of prostaglandins, thereby mitigating pain and inflammation. Myeloperoxidase (choice B) catalyzes the conversion of H2 O2 , in the presence of a halide (e.g., chloride ion) to form hypochlorous acid. This powerful oxidant is a major bactericidal agent produced by phagocytic cells. Superoxide dismutase (choice E) reduces the superoxide radical to H2 O2 .Diagnosis: Gonococcal arthritis
Cyclooxygenase
Myeloperoxidase
Phospholipase A2
Protein kinase C
Inflammation & Repair