Abstract 4034: Race /Ethnic Differences and Coronary Risk Factor Associations of Lipoprotein-Associated Phospholipase A2 (LpPLA2) in an Older Asymptomatic Cohort
Background: Lipoprotein-Associated Phospholipase A2 (LpPLA2) is an emerging biomarker of CHD. We examined 2 novel aspects of this enzyme; race/ethnicity differences and associations of LpPLA2 with LDL particle size in a healthy older cohort of 536 men and 364 women age 60–69 years.
Methods: Subjects with no evidence of CHD were randomly selected from a large northern California Health care plan and enrolled in the Atherosclerotic Disease, Vascular Function and Genetic Epidemiology (ADVANCE) study. Subjects completed baseline surveys, standard demographic, clinical and risk factor histories, a clinic visit with blood sampling for genetic and CHD biomarkers including LpPLA2 and LDL particle size. LpPLA2 was assessed using enzyme-linked immunoassays. LDL particle size was assessed by gradient gel electrophoresis. Race/ethnicity (R/E) was based on subject self-identification and grandparent country of origin and reported R/E. Mixed R/E data are not presented due to small sample sizes.
Results: Mean LpPLA2 mass and activity were highest in White men and women and were significantly different across R/E groups. After adjustment for risk factor correlates of HDL, LDL, triglycerides, peak LDL particle size, waist circumference and coronary artery calcium score, only the differences between Whites and Asians remained significant (p=0.0002 for men, p=0.002 for women). After excluding 190 persons on hypolipidemic drugs, LDL particle size was significantly correlated with LpPLA2 activity but not with LpPLA2 mass in both men (r −0.18, p=0.0003) and women (r − 0.21, p=0.0005).
Conclusions: LpPLA2 mass and activity levels differ significantly by race/ethnicity in both genders. In addition, in both genders, we found a consistent weak inverse association between LDL particle size and LpPLA2 activity suggesting that LpPLA2 activity is associated with the small dense more atherogenic form of LDL. Further research is needed to fully elucidate the associations observed.