Anti-inflammatory properties of lipid oxidation products.

Oxidative modification of lipids occurs during inflammatory processes and leads to the formation and accumulation of biologically active lipid oxidation products that induce specific cellular reactions. These reactions lead to a modulation of the inflammatory process and may determine the fate and outcome of the body's reaction in acute inflammation during host defense. The processes by which oxidized lipids may play an important role include resolution of inflammation involving apoptosis, chronic inflammatory processes, and innate and adaptive immune responses. The classical view of lipid oxidation products is that they can induce and propagate chronic inflammatory reactions. However, evidence is accumulating that cells and tissues respond towards these oxidatively formed stress signals also by activation of anti-inflammatory processes. These include defense strategies such as (a) induction of signaling pathways leading to the upregulation of anti-inflammatory genes, (b) inhibition of signaling pathways coupled to the expression of proinflammatory genes, and (c) preventing the interaction of proinflammatory bacterial products with host cells. This contribution summarizes recent findings on the anti-inflammatory action of oxidized lipoproteins and lipid oxidation products. We discuss confirmed and suggested mechanisms as well as the (patho)physiological significance of these findings.