Lipoxin A4 (LXA4)

Lipoxins are a series of anti-inflammatory mediators. Lipoxins are short lived endogenously produced nonclassic eicosanoids whose appearance in inflammation signals the resolution of inflammation. They are abbreviated as LX, an acronym for lipoxygenase (LO) interaction products. At present two lipoxins have been identified; lipoxin A₄ () and lipoxin B₄ (LXB₄).Lipoxins, as well as certain peptides, are high affinity ligands for the lipoxin A₄ receptor (LXA4R), which was first identified based on sequence homology as the formyl peptide receptor like receptor (FPRL1). Lipoxin signaling through the LXA4R inhibits chemotaxis, transmigration, superoxide generation and NF-kappa B activation. Similarly to the leukotrienes, LXA₄ will form the cysteinyl-lipoxins LXC₄, LXD₄ and LXE₄. At subnanomolar concentrations, LXA4 and LXB4 inhibit leukotriene-stimulated interactions of human neutrophils and endothelial cells.