Person:

Furtado, Jeremy

Background: High-density lipoproteins (HDL) are structurally and metabolically heterogeneous and subclasses with differential effects on coronary heart disease (CHD) might exist. Apolipoprotein (apo) C-III, a small proinflammatory protein that resides on the surface of lipoproteins, enhances the atherogenicity of VLDL and LDL particles, but little is known about the role apoC-III on HDL. We investigated whether the presence or absence of apoC-III differentiates HDL into subtypes with nonprotective or protective associations with risk of future CHD. Methods and Results: High-density lipoprotein cholesterol (HDL-C) levels were measured in plasma separated according to apoC-III (by immunoaffinity chromatography) in two prospective case-control studies nested within the Nurses’ Health and the Health Professionals Follow-Up Studies. Baseline was in 1990 and 1994, and 634 incident CHD cases were documented through 10 to 14 years of follow-up. The relative risk of CHD per each standard deviation of total HDL-C was 0.78 (95% confidence intervals, 0.63–0.96). The HDL-C subtypes were differentially associated with risk of CHD, HDL-C without apoC-III inversely and HDL-C with apoC-III directly (P=0.02 for a difference between the HDL types). The relative risk per standard deviation of HDL-C without apoC-III was 0.66 (0.53 to 0.93) and 1.18 (1.03 to 1.34) for HDL-C with apoC-III. HDL-C with apoC-III comprised ∼13% of the total HDL-C. Adjustment for triglycerides and apoB attenuated the risks; however, the two HDL-C subgroups remained differentially associated with risk of CHD (P=0.05). Conclusion: Separating HDL-C according to apoC-III identified two types of HDL with opposing associations with risk of CHD. The proatherogenic effects of apoC-III, as a component of VLDL and LDL, may extend to HDL. (J Am Heart Assoc. 2012;1:jah3-e000232 doi: 10.1161/JAHA.111.000232.)

Background: Low‐density lipoprotein (LDL) with apolipoprotein C‐III (apoC‐III) is the lipoprotein species that most strongly predicts initial and recurring coronary heart disease (CHD) events in several cohorts. Thus, a large portion of the CHD risk conferred by LDL may be attributable to LDL that contains apoC‐III. Very‐low‐density lipoprotein (VLDL) and LDL with apoC‐III have varying amounts of apoE. We hypothesized that a high content of apoE lessens the adverse influence of apoC‐III on the risk of CHD because it promotes the clearance of VLDL and LDL from plasma. Methods and Results: We studied 2 independent cohorts, the Nurses' Health Study, composed of women, and the Health Professionals Follow‐up Study, composed of men. These cohorts contributed to this study 322 women and 418 men initially free of CVD who developed a fatal or nonfatal myocardial infarction during 10 to 14 years of follow‐up and matched controls who remained free of CHD. The apoE content of LDL with apoC‐III was inversely associated with CHD after multivariable adjustment (relative risk for top versus bottom quintile 0.53, 95% CI 0.35 to 0.80). The apoE content of VLDL with apoC‐III had a similar inverse association with CHD. The highest risks were associated with a high apoB concentration and a low apoE content of LDL with apoC‐III or of VLDL+LDL with apoC‐III. The observed associations were in both male and female cohorts and independent of traditional CHD risk factors and of C‐reactive protein. Conclusions: An increased apoE content in VLDL and LDL with apoC‐III was associated with a lower risk of CHD. Strategies to enrich VLDL and LDL in apoE are worth exploring for the prevention of CHD.

BACKGROUND: Low-density lipoprotein (LDL) that contains apolipoprotein (apo) C-III makes up only 10% to 20% of plasma LDL but has a markedly altered metabolism and proatherogenic effects on vascular cells. METHODS AND RESULTS: We examined the association between plasma LDL with apoC-III and coronary heart disease in 320 women and 419 men initially free of cardiovascular disease who developed a fatal or nonfatal myocardial infarction during 10 to 14 years of follow-up and matched controls who remained free of coronary heart disease. Concentrations of LDL with apoC-III (measured as apoB in this fraction) were associated with risk of coronary heart disease in multivariable analysis that included the ratio of total cholesterol to high-density lipoprotein cholesterol, LDL cholesterol, apoB, triglycerides, or high-density lipoprotein cholesterol and other risk factors. In all models, the relative risks for the top versus bottom quintile of LDL with apoC-III were greater than those for LDL without apoC-III. When included in the same multivariable-adjusted model, the risk associated with LDL with apoC-III (relative risk for top versus bottom quintile, 2.38; 95% confidence interval, 1.54-3.68; P for trend <0.001) was significantly greater than that associated with LDL without apoC-III (relative risk for top versus bottom quintile, 1.25; 95% confidence interval, 0.76-2.05; P for trend=0.97; P for interaction <0.001). This divergence in association with coronary heart disease persisted even after adjustment for plasma triglycerides. CONCLUSIONS: The risk of coronary heart disease contributed by LDL appeared to result to a large extent from LDL that contains apoC-III.