Lipoprotein-associated phospholipase A2

In the blood Lp-PLA₂ travels mainly with low-density lipoprotein (LDL). Less than 20% is associated with high-density lipoprotein HDL. Several lines of evidence suggest that HDL-associated Lp-PLA2 may substantially contribute to the HDL antiatherogenic activities.^[8] It is an enzyme produced by inflammatory cells and hydrolyzes oxidized phospholipids in LDL.

Lp-PLA₂ is platelet-activating factor (PAF) acetylhydrolase (EC 3.1.1.47), a secreted enzyme that catalyzes the degradation of PAF to inactive products by hydrolysis of the acetyl group at the sn-2 position, producing the biologically inactive products LYSO-PAF and acetate.^[9]

Lp-PLA₂ is involved in the development of atherosclerosis,^[7] an observation that has prompted interest as a possible therapeutic target (see, e.g. the investigational drug Darapladib). In human atherosclerotic lesions, 2 main sources of Lp-PLA₂ can be identified, including that which is brought into the intima bound to LDL (from the circulation), and that which is synthesized de novo by plaque inflammatory cells (macrophages, T cells, mast cells)."

It is used as a marker for cardiac disease.^[10]

A meta-analysis involving a total of 79,036 participants in 32 prospective studies found that Lp-PLA₂ levels are positively correlated with increased risk of developing coronary heart disease and stroke.^[11]

• Darapladib