Lipid-mediated regulation of pro-inflammatory responses induced by lipopolysaccharide

Lipopolysaccharide (LPS, endotoxin) is the component of the outer membrane of Gramnegative bacteria which upon infection induces the body's inflammatory reaction facilitating eradication of pathogens. However, exaggerated reactions to LPS can lead to potentially deadly sepsis while chronic, low-grade inflammation is linked with the development of several metabolic diseases, like type 2 diabetes. These processes are initiated by the binding of LPS to CD14 protein and the TLR4/MD2 receptor complex located in the plasma membrane of immune cells and also by the activation of a cytoplasmic multi-protein complex called the inflammasome. Recent studies have shown that lipids of the plasma membrane and endomembranes are important regulators of LPS-triggered signaling pathways. In this review we summarize those data emphasizing the role of phosphatidylinositols and modification of proteins by palmitoylation. Dysregulation of the lipid-dependent steps of the LPS-induced signaling can lead to excessive production of cytokines during sepsis and metabolic diseases linked with endotoxemia.