Abstract 1607: Lipoprotein(a) and Vascular Inflammation: Association of Lipoprotein-associated Phospholipase A2 Activity With Lipoprotein(a) in African Americans
Background: Lipoprotein-associated phospholipase A2 (Lp-PLA2) and lipoprotein (a) (Lp(a)) have been implicated as cardiovascular disease (CVD) risk factors. Levels of Lp(a) and Lp-PLA2 are inversely regulated in African Americans and Caucasians, suggesting a different relationship between these risk factors across ethnicity. Objective: We investigated the association between Lp-PLA2 activity and allele-specific apo(a) levels in African Americans and Cauca-sians.
Methods: Lp(a) levels, apo(a) size, allele-specific apo(a) levels and Lp-PLA2 activity were determined in 224 African Americans and 336 Caucasians.
Results: As expected, Lp-PLA2 activity level was higher among Caucasians compared to African Americans (173±41 vs. 141±39 nmol/min/mL, P<0.001). Irrespective of ethnicity, Lp-PLA2 activity was positively associated with total and LDL cholesterol, triglyceride, Lp(a) and apolipoprotein B-100, and negatively with HDL cholesterol levels. Across Lp-PLA2 activity tertiles, plasma Lp(a) levels were two fold higher among African Americans compared to Caucasians (P<0.001) and the Lp(a) levels in the upper two tertiles were significantly increased compared to the lowest among African Americans (P=0.003). The Lp-PLA2 activity level was associated with allele-specific apo(a) levels among African Americans (P<0.001), but not in Caucasians. Moreover, the allele-specific apo(a) levels were significantly increased in the upper two Lp-PLA2 tertiles (P=0.002) compared to the lowest among African Americans. However, in Caucasians, allele-specific apo(a) levels carrying less than 26 K4 repeats were significantly associated with Lp-PLA2 activity.
Conclusion: Allele-specific apo(a) levels were significantly associated with the Lp-PLA2 activity level in African Americans. In contrast, the Lp-PLA2 activity level was associated only with allele-specific “smaller” apo(a) levels in Caucasians. The results underscore a close relation between small size apo(a) alleles and Lp-PLA2 activity, a marker of vascular inflammation. Our findings suggest a synergistic effect between Lp(a) and Lp-PLA2 in promoting vascular inflammation.
This research has received full or partial funding support from the American Heart Association, Western States Affiliate (California, Nevada & Utah).