A matrix of cholesterol crystals, but not cholesterol alone, primes human monocytes/macrophages for excessive endotoxin-induced production of tumor necrosis factor-alpha. Role in atherosclerotic inflammation?
When exposed to small amounts of bacterial endotoxin, matrices of cholesterol crystals, but not cholesterol itself, primed human monocytes/macrophages to a highly augmented (>10-fold) production of inflammatory tumor necrosis factor-α. Priming also sensitized the cells, as 10- to 100-fold lower levels of endotoxin were needed for TNF-α production equivalent to that of unprimed cells. The pro-inflammatory effect was selective as endotoxin-induced production of other pro-inflammatory cytokines was unaffected while production of anti-inflammatory interleukin-10 was diminished. These findings suggest that cholesterol matrix formation may play a pathogenic role in atherosclerotic inflammation, and they indicate a mechanism by which bacteria and/or bacterial products may play a role in processes leading to arteriosclerosis.