Blood biomarker underscores role of inflammation in vascular disease

UC Davis researchers have discovered that a blood component linked with inflammation can predict coronary artery disease in African-Americans.

Known as lipoprotein-associated phospholipase A2 (Lp-PLA2), the blood factor is also associated with but does not accurately predict heart-disease risk in Caucasians. The findings are published in the current issue of the Journal of Clinical Endocrinology and Metabolism.

"This study suggests that inflammation may be a more important mechanism in heart disease for African-Americans than it is for Caucasians and increases our growing understanding of how heart-disease processes vary in different ethnic groups," said Lars Berglund, senior study author and associate dean for research at the UC Davis School of Medicine. "The more we appreciate such differences, the better we can individualize treatment and prevention approaches."

Lp-PLA2 was recently identified as a marker for the inflammatory processes involved in atherosclerosis. It is considered key to the progression and rupture of fatty plaques that can block coronary arteries and lead to heart attacks. It predominately binds to low-density lipoprotein - or LDL - which is a general marker of increased heart-disease risk. Berglund noted, though, that more well-known factors like LDL and high cholesterol cannot provide the whole picture of heart disease.

"There are other important elements of heart disease - like inflammation - that need to be better explained," he said.

For the current study, Berglund and his team measured Lp-PLA2 levels in the blood of 336 Caucasians and 224 African-Americans who were about to undergo diagnostic coronary arteriography - a test used to determine coronary artery disease in high-risk patients - at two hospitals in New York. Coronary arteriography findings were compared with the amount and activity levels of Lp-PLA2 from each research subject.

During the procedure, contrast dye and X-rays are used to detect narrowed or blocked arteries, indicating the potential for heart attacks.

"Arteriography is highly effective but considered too risky and expensive for general screening," said Berglund. "That is why researchers are always on the lookout for other reliable predictors of heart-attack risk that can be identified with a simple blood test."

The outcomes showed that Lp-PLA2 activity was higher among Caucasians and African-Americans with coronary artery disease. In addition, only in African-Americans was the Lp-PLA2 index found to independently predict coronary artery disease.

Although the test for Lp-PLA2 is widely available, Berglund said it is too soon to recommend widespread testing to affect treatment decisions. The study population was not representative of the general population as all participants already had symptoms of heart disease. Berglund's team plans further studies of Lp-PLA2 and other inflammatory components of the blood in a wider range of patients to get a clearer picture of their roles in predicting heart disease for different ethnic and racial groups. The outcomes of his current study, however, give him hope that African-Americans at high risk for heart disease will one day be treated for inflammation more aggressively and earlier in the disease process.

"This study has helped open the field," said Berglund. "More information will allow us to better tailor therapy to specific patient needs."