Apolipoprotein(a) size polymorphism is associated with coronary heart disease in polygenic hypercholesterolemia

Lipoprotein (a) as a cause of cardiovascular disease: insights from epidemiology, genetics, and biology

Human epidemiologic and genetic evidence using the Mendelian randomization approach in large-scale studies now strongly supports that elevated lipoprotein (a) [Lp(a)] is a causal risk factor for cardiovascular disease, that is, for myocardial infarction, atherosclerotic stenosis, and aortic valve stenosis. The Mendelian randomization approach used to infer causality is generally not affected by confounding and reverse causation, the major problems of observational epidemiology. This approach is particularly valuable to study causality of Lp(a), as single genetic variants exist that explain 27-28% of all variation in plasma Lp(a). The most important genetic variant likely is the kringle IV type 2 (KIV-2) copy number variant, as the apo(a) product of this variant influences fibrinolysis and thereby thrombosis, as opposed to the Lp(a) particle per se. We speculate that the physiological role of KIV-2 in Lp(a) could be through wound healing during childbirth, infections, and injury, a role that, in addition, could lead to more blood clots promoting stenosis of arteries and the aortic valve, and myocardial infarction. Randomized placebo-controlled trials of Lp(a) reduction in individuals with very high concentrations to reduce cardiovascular disease are awaited. Recent genetic evidence documents elevated Lp(a) as a cause of myocardial infarction, atherosclerotic stenosis, and aortic valve stenosis.

Decreased plasma levels of soluble receptor for advanced glycation end-products in patients with essential hypertension

OBJECTIVES

Advanced glycation end-products (AGE) may cause vascular stiffening by forming crosslinks through the collagen molecule or by interaction with their cellular transductional receptor (RAGE). A secreted isoform of RAGE, termed soluble RAGE (sRAGE), may contribute to the removal/detoxification of AGE by acting as a decoy. Here we studied the plasma sRAGE levels in hypertensive and normotensive human subjects. We also investigated the relationship between blood pressure parameters and plasma sRAGE concentrations.

DESIGN

A cross-sectional case-control study.

SETTING AND PARTICIPANTS

The outpatient clinic of a university teaching hospital. Participants were 147 never-treated patients with essential hypertension (87 men and 60 women, aged 50 +/- 10 years) and 177 normotensive controls (118 men and 59 women, aged 49 +/- 10 years).

MAIN OUTCOME MEASURES

Plasma sRAGE levels determined by enzyme-linked immunosorbent assay, systolic blood pressure (SBP), diastolic blood pressure, pulse pressure (PP) and mean arterial pressure.

RESULTS

The plasma concentration of sRAGE [median (interquartile range)] was 1206 (879-1658) pg/ml in hypertensive subjects and 1359 (999-2198) pg/ml in normotensive controls (P = 0.002). Simple correlation analysis revealed that log-transformed sRAGE levels were inversely correlated with SBP (r = -0.11; P < 0.001) and PP (r = -0.23; P < 0.001). Forward-selection multiple regression analysis revealed that log-transformed sRAGE levels were determined more strongly by PP (F = 3.127, P < 0.001).

CONCLUSIONS

Plasma sRAGE levels are decreased in patients with essential hypertension and are inversely related to PP. Our results raise the possibility that sRAGE may play a role in arterial stiffening and its complications.