The strange case of Dr HDL and Mr HDL: Does a NO’s story illuminate the mystery of HDL’s dark side uncovered by Dr HDL’s drug targeting CETP?

Circulating plasma cholesteryl ester transfer protein activity and blood pressure tracking in the community

OBJECTIVE

Clinical trials using cholesteryl ester transfer protein (CETP) inhibitors to raise high-density lipoprotein cholesterol (HDL-C) concentrations reported an 'off-target' blood pressure (BP) raising effect. We evaluated the relations of baseline plasma CETP activity and longitudinal BP change.

METHODS AND RESULTS

One thousand, three hundred and seven Framingham Study participants free of cardiovascular disease attending consecutive examinations 4 years apart (mean age 48 years) had baseline plasma CETP activity related to change in BP over the 4-year interval, adjusting for standard risk factors. Systolic BP increased [median +2 mmHg, 95% confidence interval (CI) -16,+23 mmHg], whereas diastolic BP decreased (median -3 mmHg, 95% CI -15,+11 mmHg). Plasma CETP activity was not related to change in diastolic BP, but was inversely related to change in systolic BP that was borderline significant (P=0.09). On multivariable analyses, plasma CETP activity was inversely related to change in pulse pressure (PP; beta per SD increment= -0.71 mmHg, P=0.005). When dichotomized at the median, plasma CETP activity above the median was associated with a 1 mmHg lower PP on follow-up (P=0.045).

CONCLUSION

Decreasing plasma CETP activity was modestly related to increasing PP on follow-up in our community-based sample, suggesting that inhibition of intrinsic CETP activity itself is likely associated with minimal changes in BP.

Apolipoprotein A-I mimetic peptides: a potential new therapy for the prevention of atherosclerosis

The beneficial effects of high-density lipoprotein (HDL) on atherosclerosis have largely been attributed to its major protein, apolipoprotein A-I (apoA-I). Used as a therapeutic intervention, apoA-I is a large protein that requires venous administration, and is both difficult and expensive to manufacture. Because of these problems with apoA-I, the generation of smaller, easier to manufacture apoA-I mimetic peptides has become a target for pharmacologic development in the therapeutic management of human atherosclerosis. A potent apoA-I mimetic peptide, 4F, was found to have significant activity in various inflammatory states in both mice and monkeys. The anti-inflammatory and antiatherogenic effects of 4F include increased pre-beta HDL formation, increased cholesterol efflux, the conversion of pro-inflammatory HDL to anti-inflammatory HDL, and reduced lipoprotein oxidation. In addition, improved arterial vasoreactivity is another important function of 4F. In a rat model of diabetes, D-4F increased arterial concentrations of heme oxygenase-1 (HO-1) and superoxide dismutase, decreased superoxide levels, reduced levels of circulating endothelial cells, decreased endothelial cell fragmentation, and restored arterial vasoreactivity to normal. In a mouse model of systemic sclerosis, D-4F functioned to improve vasodilation and angiogenic potential, while reducing myocardial inflammation and oxidative stress. With respect to mouse models of heart transplant-associated atherosclerosis, D-4F induced HO-1. In addition, D-4F was shown to improve cognitive performance in low-density lipoprotein-receptor null mice with Western diet-induced cognitive decline. D-4F also reduced the kidney content of oxidized phospholipids in a mouse model of hyperlipidemia-induced renal inflammation. In early human studies in patients with significant cardiovascular risk, a single dose of oral D-4F was found to safely improve the anti-inflammatory index of HDL. L-4F is also being studied in clinical trials as a potential treatment modality for obesity and the metabolic syndrome.

Coronary artery endothelial dysfunction is positively correlated with low density lipoprotein and inversely correlated with high density lipoprotein subclass particles measured by nuclear magnetic resonance spectroscopy

OBJECTIVE

The association between cholesterol and endothelial dysfunction remains controversial. We tested the hypothesis that lipoprotein subclasses are associated with coronary endothelial dysfunction.

METHODS AND RESULTS

Coronary endothelial function was assessed in 490 patients between November 1993 and February 2007. Fasting lipids and nuclear magnetic resonance (NMR) lipoprotein particle subclasses were measured. There were 325 females and 165 males with a mean age of 49.8+/-11.6 years. Coronary endothelial dysfunction (epicardial constriction>20% or increase in coronary blood flow<50% in response to intracoronary acetylcholine) was diagnosed in 273 patients, the majority of whom (64.5%) had microvascular dysfunction. Total cholesterol and LDL-C (low density lipoprotein cholesterol) were not associated with endothelial dysfunction. One-way analysis and multivariate methods adjusting for age, gender, diabetes, hypertension and lipid-lowering agent use were used to determine the correlation between lipoprotein subclasses and coronary endothelial dysfunction. Epicardial endothelial dysfunction was significantly correlated with total (p=0.03) and small LDLp (LDL particles) (p<0.01) and inversely correlated with total and large HDLp (high density lipoprotein particles) (p<0.01).

CONCLUSIONS

Epicardial, but not microvascular, coronary endothelial dysfunction was associated directly with LDL particles and inversely with HDL particles, suggesting location-dependent impact of lipoprotein particles on the coronary circulation.