Bioactive lipids are produced from the metabolism of cellular membrane components. The eicosanoid class of mediators includes thromboxanes, prostaglandins, and leukotrienes which are derived from the lipid metabolite arachidonic acid. Arachidonic can be released from phospholipids or diacylglycerol and then is metabolized by a range of enzymes to produce the active eicosanoids. A distinct class of bioactive lipids includes lysophosphatidic acid (LPA), sphingosine-1-phosphate (SIP), and the endocannabinoids. These molecules are derived from lysophosphatidylcholine, sphingolipids, or anandamide.
Bioactive lipids function as both paracrine and autocrine regulators, and they interact with G protein-coupled receptors on myeloid and lymphoid immune cells, smooth muscle cells, neurons, and epithelial cells. They regulate wide-ranging activities including smooth muscle contraction in the vasculature, airway, and gastrointestinal tract as well as the chemotaxis and activation of neutrophils and mast cells during inflammation. In addition, they regulate brain development, sleep, embryo implantation, hair growth, adiposity, neuropathic pain, pulmonary fibrosis, tumorigenesis, and asthma.