| Description | LysoPC(14:0/0:0) is a lysophospholipid (LyP). It is a monoglycerophospholipid in which a phosphorylcholine moiety occupies a glycerol substitution site. Lysophosphatidylcholines can have different combinations of fatty acids of varying lengths and saturation attached at the C-1 (sn-1) position. Fatty acids containing 16, 18 and 20 carbons are the most common. LysoPC(14:0/0:0), in particular, consists of one chain of myristic acid at the C-1 position. The myristic acid moiety is derived from nutmeg and butter. Lysophosphatidylcholine is found in small amounts in most tissues. It is formed by hydrolysis of phosphatidylcholine by the enzyme phospholipase A2, as part of the de-acylation/re-acylation cycle that controls its overall molecular species composition. It can also be formed inadvertently during extraction of lipids from tissues if the phospholipase is activated by careless handling. In blood plasma significant amounts of lysophosphatidylcholine are formed by a specific enzyme system, lecithin:cholesterol acyltransferase (LCAT), which is secreted from the liver. The enzyme catalyzes the transfer of the fatty acids of position sn-2 of phosphatidylcholine to the free cholesterol in plasma, with formation of cholesterol esters and lysophosphatidylcholine. Lysophospholipids have a role in lipid signaling by acting on lysophospholipid receptors (LPL-R). LPL-R's are members of the G protein-coupled receptor family of integral membrane proteins. LPL-R's are members of the G protein-coupled receptor (GPR) family of integral membrane proteins. Lysophosphatidylcholines (LPCs) specifically bind to GPR119, GPR40, GPR55 and GPR4. binding of LPCs to GPR119, GPR40 and GPR55 induces intracellular calcium mobilization and leads to increased glucose-stimulated insulin secretion in different cell systems. In blood or plasma LPCs are bound mainly to albumin and to a lesser extent to lipoproteins. Inflammation, cell damage and other pathophysiological conditions can profoundly alter the ratio of free to albumin bound LPC through increased production of LPC or decreased plasma levels of albumin (PMID: 32599910 ). In particular, lower levels of albumin (hypoalbuminemia) lead to lower levels of LPC in the blood. Hypoalbuminemia with albumin concentrations of <20 g/L are typical of patients with sepsis, burns or serious trauma (PMID: 26557421 ). Such low levels of albumin often lead to LPC levels that are 50-80 % lower than that seen in healthy individuals (PMID: 27501420 ). Decreased levels of LPC have been observed in a number of other inflammatory conditions beyond sepsis, including rheumatoid arthritis, diabetes, schizophrenia, polycystic ovary syndrome, Alzheimer’s disease, pulmonary arterial hypertension, aging, asthma and liver cirrhosis, where they were associated with increased mortality risk (PMID: 32599910 ). LPCs have a number of protective or anti-inflammatory effects. Higher levels of LPC induce cyclooxygenase-2 and endothelial nitric oxide synthase (eNOS) expression in endothelial cells, both of which can have vasoprotective effects either via production of prostacyclin or nitric oxide (PMID: 32599910 ). LPCs have been shown to elicit a number of effects on the innate immune system and effectively serve as dual-activity ligand molecules. In particular, LPCs directly activate toll-like receptor (TLR) 4 and TLR-2-1 receptors in the absence of classical TLR ligands. However, LPCs can also inhibit TLR-mediated signaling in the presence of classical TLR ligands, thereby acting as anti-inflammatory molecules (PMID: 32599910 ). Low levels of LPC during a bacterial or viral infection with TLR-mediated signalling can lead to opposing (inflammatory vs. anti-inflammatory) effects and immune dysregulation. |
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