High levels of inflammatory biomarkers are associated with increased allele-specific apolipoprotein(a) levels in African-Americans.
BACKGROUND
A role of inflammation for cardiovascular disease (CVD) is established. Lipoprotein(a) [Lp(a)] is an independent CVD risk factor where plasma levels are determined by the apolipoprotein(a) [apo(a)] gene, which contains inflammatory response elements.


METHODS
We investigated the effect of inflammation on allele-specific apo(a) levels in African-Americans and Caucasians. We determined Lp(a) levels, apo(a) sizes, allele-specific apo(a) levels, fibrinogen and C-reactive protein (CRP) levels in 167 African-Americans and 259 Caucasians.


RESULTS
Lp(a) levels were increased among African-Americans with higher vs. lower levels of CRP [<3 vs. > or =3 mg/liter (143 vs. 108 nmol/liter), P = 0.009] or fibrinogen (<340 vs. > or =340 mg/liter, P = 0.002). We next analyzed allele-specific apo(a) levels for different apo(a) sizes. No differences in allele-specific apo(a) levels across CRP or fibrinogen groups were seen among African-Americans or Caucasians for small apo(a) sizes (<22 kringle 4 repeats). Allele-specific apo(a) levels for medium apo(a) sizes (22-30 kringle 4 repeats) were significantly higher among African-Americans, with high levels of CRP or fibrinogen compared with those with low levels (88 vs. 67 nmol/liter, P = 0.014, and 91 vs. 59 nmol/liter, P < 0.0001, respectively). No difference was found for Caucasians.


CONCLUSIONS
Increased levels of CRP or fibrinogen are associated with higher allele-specific medium-sized apo(a) levels in African-Americans but not in Caucasians. These findings indicate that proinflammatory conditions result in a selective increase in medium-sized apo(a) levels in African-Americans and suggest that inflammation-associated events may contribute to the interethnic difference in Lp(a) levels between African-Americans and Caucasians.
Anuurad
Erdembileg
E
Department of Medicine, University of California, Davis, Sacramento, California 95817, USA.
Rubin
Jill
J
Chiem
Alan
A
Tracy
Russell P
RP
Pearson
Thomas A
TA
Berglund
Lars
L
D001741:Black or African American / Q000235:genetics*; D000483:Alleles; D053241:Apoprotein(a) / Q000097:blood*; D015415:Biomarkers; D002097:C-Reactive Protein / Q000032:analysis*; D005260:Female; D005340:Fibrinogen / Q000032:analysis*; D006801:Humans; D007249:Inflammation / Q000208:ethnology*; D008297:Male; D044465:White People
D015415:Biomarkers; D005340:Fibrinogen; D002097:C-Reactive Protein; D053241:Apoprotein(a)