Lipoprotein-associated phospholipase A2 – pro

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is an enzyme that is produced by inflammatory cells, co-travels with circulating low-density lipoprotein (LDL), and hydrolyzes oxidized phospholipids in LDL. Its biological role has been controversial with initial reports purporting atheroprotective effects of Lp-PLA2 thought to be a consequence of degrading platelet-activating factor and removing polar phospholipids in modified LDL. Recent studies, however, focused on pro-inflammatory role of Lp-PLA2 mediated by products of the Lp-PLA2 reaction (lysophosphatidylcholine and oxidized nonesterified fatty acids). These bioactive lipid mediators, which are generated in lesion-prone vasculature and to a lesser extent in the circulation (eg, in electronegative LDL), are known to elicit several inflammatory responses. The proinflammatory action of Lp-PLA2 is also supported by a number of epidemiology studies suggesting that the circulating level of the enzyme is an independent predictor of cardiovascular events, despite some attenuation of the effect by inclusion of LDL, the primary carrier of Lp-PLA2, in the analysis.

Ascribing a role for Lp-PLA2, an enzyme that is produced by inflammatory cells, is transported on circulating LDL and hydrolyzes oxidized phospholipids in LDL, has been controversial. A growing number of epidemiological studies suggest that Lp-PLA2 is an independent predictor of cardiovascular events, despite some attenuation of this relationship by LDL, the primary carrier of Lp-PLA2. These observations strengthen the rationale to explore causal links between Lp-PLA2 and plaque vulnerability. The connection to cardiovascular diseae and Alzheimer’s remain unproven; neither are the effects of  interventions to reduce the level of this marker known. Empire considers this test to be be not medically necessary.

A.-L. Levonen, E. Vahakangas, J. K. Koponen, and S. Yla-Herttuala
Antioxidant Gene Therapy for Cardiovascular Disease: Current Status and Future Perspectives
Circulation, April 22, 2008; 117(16): 2142 – 2150.

W. Koenig
Cardiovascular Biomarkers: Added Value With an Integrated Approach?
Circulation, July 3, 2007; 116(1): 3 – 5.

A. Oldgren, S. K. James, A. Siegbahn, and L. Wallentin
Lipoprotein-associated phospholipase A2 does not predict mortality or new ischaemic events in acute coronary syndrome patients
Eur. Heart J., March 2, 2007; 28(6): 699 – 704.

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