Apolipoprotein-containing lipoprotein subclasses and subclinical atherosclerosis In systemic lupus erythematosus (SLE).
Objectives: Traditional classification of hyperlipidemia using HDL, LDL and VLDL does not provide information on lipoprotein function. Apolipoproteins, (which are protein components of plasma lipoproteins including A, B, C, D, E) with their different composition, metabolic and atherogenic properties, provide insight on lipoprotein functioning. In particular, the ApoB/A-1 ratio is associated with atherogenic LDL and development of cardiovascular disease. We explored the baseline association between these non-traditional risk factors with subclinical measures of atherosclerosis (coronary artery calcium and carotid intima-media thickness) in SLE. Methods: 58 SLE patients (97% female, 58% Caucasian, 40% African-American, 2% other, mean age 44±11 yrs) had measurement of apolipoprotein and lipoproteins by immunoturbidimetric procedures, electroimmunoassays and immunoprecipitation. Coronary artery calcium was measured by helical CT and carotid intima-media thickness by carotid duplex. This study was based on the baseline assessment of subclinical atherosclerosis in the LAPS study. The measurement of the lipoproteins was made on sera collected at the same time. Results: There was no association between cardioprotective apoliporoteins (apoA-I, LpA-I, LpA-I:AII) and coronary artery calcium (p<0.15,0.41,0.39) or carotid intima-media thickness (p<0.97,0.53,0.76). Coronary artery calcium and carotid intima-media thickness did not associate with atherogenic apolipoproteins either, including LpB:E+LpB:C:E, apoB, LpB, LpB:C, apoC-III, apoC-III-HS, apoC-III-HP, CIII-R, LpA-II:B:C:D:E and apoB/apoA-I. Measures of disease activity, including physician's global assessment and SLEDAI, were not associated with coronary artery calcium or carotid intima-media thickness. Conclusion: Neither cardioprotective nor atherogenic lipoproteins were associated with measures of subclinical atherosclerosis in this series of SLE patients. Further studies with larger sample size are warranted to confirm our findings. © 2014 American College of Rheumatology.