Lp-PLA2 (Lipoprotein-associated phospholipase A2) - also known as platelet-activating factor acetylhydrolase (PAF-AH) - is a vascular-specifc inflammatory enzyme, predominantly expressed by macrophages, lymphocytes and foam cells in atherosclerotic plaques. Circulating Lp-PLA2 is mainly associated with apolipoprotein B-containing lipoproteins, hence closely associated with low-density lipoprotein (LDL). The enzyme hydrolyzes oxidized phospholipids on LDL particles within the arterial intima, generating two highly inflammatory mediators, lysophosphatidylcholine (Lyso-PC) and oxidized non-esterified fatty acids (oxNEFAs).
Many important studies confirm a strong association between Lp-PLA2 levels and cardiovascular risk among different populations. These studies show that in individuals with normal LDL, elevated Lp-PLA2 levels were strongly associated with heart disease and ischemic stroke, independent of traditional risk markers and high-sensitive CRP. Due to the fact that Lp-PLA2 is involved in the causal pathway of plaque inflammation and plaque rupture, the testing for Lp-PLA2 represents a valuable adjunctive tool which goes beyond traditional cardiovascular risk assessment.
The importance of Lp-PLA2 testing
It is well known, that inflammatory processes play an important role in the pathogenesis of atherosclerosis. Established risk factors account for part of the cardiovascular diseases only. Lp-PLA2, a new reliable marker in the atherosclerotic risk assessment, is able to close this diagnostic gap.
Studies provide strong evidence, that the presence of Lp-PLA2 is associated with an increased risk of cardiac death, myocardial infarction, acute coronary syndrome and ischemic stroke. Increased Lp-PLA2 concentrations can be found in vulnerable atherosclerotic plaques and allow discrimination between morphologically identical stable and unstable plaques. Lp-PLA2 testing is an excellent complement to angiography because it detects very small plaques not visible by medical imaging. Unlike traditional atherosclerotic risk markers Lp-PLA2 is highly specifc for vascular inflammation, has low biological variability, and plays a causative role in atherosclerotic plaque inflammation.