Impaired phosphatidylcholine biosynthesis reduces atherosclerosis and prevents lipotoxic cardiac dysfunction in ApoE-/- Mice.

RATIONALE

Phosphatidylcholine (PC) is the predominant phospholipid component of circulating lipoproteins. The majority of PC is formed by the choline pathway. However, approximately one-third of hepatic PC can also be synthesized by phosphatidylethanolamine N-methyltransferase (PEMT). PEMT is required for normal secretion of very-low-density lipoproteins from the liver. We hypothesized that lack of PEMT would attenuate atherosclerosis and improve myocardial function.

OBJECTIVE

Investigate the contribution of PEMT to atherosclerotic lesion formation and cardiac function in mice that lack apolipoprotein E.

METHODS AND RESULTS

Mice deficient in apolipoprotein E (Pemt(+/+)/Apoe(-/-)) and mice lacking both PEMT and apoE (Pemt(-/-)/Apoe(-/-)) were fed a chow diet for 1 year. The atherogenic lipoprotein profile of plasma of Apoe(-/-) mice was significantly improved by PEMT deficiency, with lower levels of triacylglycerol (45%) and cholesterol (≈25%) in the very-low-density lipoprotein and low-density/intermediate-density lipoprotein fractions, respectively (P < 0.05). Atherosclerotic lesion area was reduced by ≈30%, and aortic cholesteryl ester and cholesterol content were also reduced by ≈40% by PEMT deficiency (P < 0.05). By in vivo echocardiography, we detected a ≈50% improvement in systolic function in the Pemt(-/-)/Apoe(-/-) compared with Pemt(+/+)/Apoe(-/-) mice (P < 0.05). This was accompanied by a significant reduction in cardiac triacylglycerol (34%) in mice lacking PEMT.

CONCLUSIONS

These results indicate that treatment strategies aimed at inhibition of PEMT might prevent the accumulation of cardiac triacylglycerol that predisposes individuals to compromised cardiac function.