Gout, uric acid metabolism, and crystal-induced inflammation

Serum triglyceride levels are significantly higher and serum high-density lipoprotein cholesterol levels are lower in patients with gout compared with healthy individuals. Whereas increased serum triglyceride levels exist intrinsically in gout, serum uric acid concentration correlates inversely with insulin sensitivity and positively with serum triglycerides. Interaction of monosodium urate crystals with granulocyte-macrophage colony-stimulating factor and with tumor necrosis factor-activated neutrophils favored the production of interleukin-1 over that of interleukin-1-Ra, resulting in a proinflammatory imbalance. Interaction of the crystals with iron or tyrosine kinase may modify their inflammatory response and can be an important modulating mechanism in gouty arthritis. E-selectin is a specific marker for synovial fluid soluble endothelial activity and is increased in the synovial fluid of patients with gouty arthritis, as well as in that of patients with other inflammatory arthritides. Similarly, E-selectin was found to be high in joints with monosodium urate crystal-induced synovitis. In addition, synovial fluid levels of interleukin-8 were found to be high in gout, rheumatoid arthritis, and osteoarthritis.