Clinical significance of measuring soluble LR11, a circulating marker of atherosclerosis and HbA1c in familial hypercholesterolemia.

OBJECTIVES: The LDL receptor relative with 11 ligand-binding repeats (LR11) is closely related to atherosclerotic disease or diabetes. The aim of the study was to clarify how soluble LR11 was related to Achilles' tendon thickness (ATT) and HbA1c in familial hypercholesterolemia. DESIGN AND METHODS: The present study is a cross-sectional case-control study. We enrolled twenty-four patients with heterozygous FH (age 51.0±20.0 year; male, 50%; 20 cases with LDL receptor mutation, 1 case with proprotein convertase subtilisin/kexin type 9 (PCSK9) E32K and 3 cases without confirmed mutations). Soluble LR11 (sLR11) was measured using a sandwich enzyme-linked immunosorbent assay method. RESULTS: Univariate regression analysis showed that sLR11 had positive correlations with age and HbA1c, and inverse correlations with apoA1 in FH. There were also positive correlations of sLR11 with apoE, IDL-C and average ATT. Multivariate regression analysis showed that there were positive correlations of sLR11 to IDL-C and HbA1c independent of age and BMI. In another multivariate regression analysis on the relationships of average ATT as a dependent variable with age, BMI and sLR11 (IDL-C and HbA1c) as independent variables, sLR11 had a positive correlation with average ATT, independent of age and BMI. However, this independency did not persist after adding IDL-C and HbA1c as confounding factors. Of special note is that HbA1c showed a significant correlation with average ATT, independent of other parameters including sLR11. CONCLUSION: It is crucial to intervene in the existence of remnant lipoprotein as well as hypercholesterolemia from an early stage and conduct glycemic control to prevent the progression of atherosclerotic disease in FH.

Expression profiling of the ephrin (EFN) and Eph receptor (EPH) family of genes in atherosclerosis-related human cells.

Ephrin B1 and its cognate receptor, Eph receptor B2, key regulators of embryogenesis, are expressed in human atherosclerotic plaque and inhibit adult human monocyte chemotaxis. Few data exist, however, regarding the gene expression profiles of the ephrin (EFN) and Eph receptor (EPH) family of genes in atherosclerosis-related human cells. Gene expression profiles were determined of all 21 members of this gene family in atherosclerosis-related cells by reverse transcription-polymerase chain reaction analysis. The following 17 members were detected in adult human peripheral blood monocytes: EFNA1 and EFNA3 - EFNA5 (coding for ephrins A1 and A3 - A5); EPHA1, EPHA2, EPHA4 - EPHA6 and EPHA8 (coding for Eph receptors A1, A2, A4 - A6 and A8); EFNB1 and EFNB2 (coding for ephrins B1 and B2); and EPHB1 - EPHB4 and EPHB6 (coding for Eph receptors B1 - B4 and B6). THP-1 monocytic cells, Jurkat T cells and adult arterial endothelial cells also expressed multiple EFN and EPH genes. These results indicate that a wide variety of ephrins and Eph receptors might affect monocyte chemotaxis, contributing to the development of atherosclerosis. Their pathological significance requires further study.

A novel method for measuring human lipoprotein lipase and hepatic lipase activities in postheparin plasma.

The objective of this study was to establish a new lipoprotein lipase (LPL) and hepatic lipase (HL) activity assay method. Seventy normal volunteers were recruited. Lipase activities were assayed by measuring the increase in absorbance at 546 nm due to the quinoneine dye. Reaction mixture-1 (R-1) contained dioleoylglycerol solubilized with lauryldimethylaminobetaine, monoacylglycerol-specific lipase, glycerolkinase, glycerol-3-phosphate oxidase, peroxidase, ascorbic acid oxidase, and apolipoprotein C-II (apoC-II). R-2 contained Tris-HCl (pH 8.7) and 4-aminoantipyrine. Automated assay of lipase activities was performed with an automatic clinical analyzer. In the assay for HL + LPL activity, 160 microl R-1 was incubated at 37 degrees C with 2 microl of sample for 5 min, and 80 microl R-2 was added. HL activities were measured under the same conditions without apoC-II. HL and LPL activities were also measured by the conventional isotope method and for HL mass by ELISA. Lipase activity detected in a 1.6 M NaCl-eluted fraction from a heparin-Sepharose column was enhanced by adding purified apoC-II in a dose-dependent manner, whereas that eluted by 0.8 M NaCl was not. Postheparin plasma-LPL and HL activities measured in the present automated method had high correlations with those measured by conventional activity and mass methods. This automated assay method for LPL and HL activities is simple and reliable and can be applied to an automatic clinical analyzer.

Comparison of effects of pitavastatin and atorvastatin on plasma coenzyme Q10 in heterozygous familial hypercholesterolemia: results from a crossover study.

An open, randomized, four-phased crossover study using 4 mg of pitavastatin or 20 mg of atorvastatin was performed to compare their efficacy and safety, especially regarding plasma levels of coenzyme Q10 (CoQ10) in 19 Japanese patients with heterozygous familial hypercholesterolemia. Pitavastatin and atorvastatin caused significant and almost comparable reductions in serum levels of total cholesterol (-35.4 vs. -33.8%), low-density lipoprotein cholesterol (-42.8 vs. -40.7%), and triglyceride (-26.1 vs. -29.4%), and significantly increased serum levels of high-density lipoprotein cholesterol (12.1 vs. 11.4%). Under these conditions, plasma levels of CoQ10 were reduced by atorvastatin (-26.1%, P=0.0007) but not by pitavastatin (-7.7%, P=0.39), although no adverse events or abnormalities of liver and muscle enzyme were observed after either statin treatment. It remains to be seen whether the observed changes in CoQ10 levels are related to the long-term safety of this drug.

Circulating matrix metalloproteinases and their inhibitors in premature coronary atherosclerosis.

To investigate the clinical significance of circulating matrix metalloproteinases (MMPs) and their tissue inhibitos (TIMPs) in patients with premature coronary atheroscrelosis, we studied 53 consecutive male patients with angiographically defined premature (<65 years) and stable coronary artery disease. Plasma levels of MMP-2, MMP-3, MMP-9, TIMP-1, and TIMP-2 were determined in peripheral blood by a sandwich enzyme immunoassay, and the results were compared with those from 133 age-matched control males. There were significant differences in all the MMPs and TIMPs (p<0.001) between patients and controls. In the patient group, the levels of MMP-9 (mean +/- SD (ng/ml) 27.2 +/- 15.2/21.8 +/- 15.2) and TIMP-1 (130.4 +/- 55.7/94.5 +/- 26.3) were significantly higher, and the levels of MMP-2 (632.5 +/- 191.6/727.6 +/- 171.4), MMP-3 (53.1 +/- 31.2/79.6 +/- 29.9), and TIMP-2 (24.7 +/- 15.2/35.4 +/- 16.4) were significantly lower than those of controls. We found significant positive correlation between plasma MMP-9 levels and low-density lipoprotein (LDL)-cholesterol levels (Rs = 0.168, p = 0.022), and significant negative correlation between plasma MMP-9 levels and high-density lipoprotein (HDL)-cholesterol levels (Rs = -0.164, p = 0.026) by Spearman rank correlation test. In contrast, plasma MMP-2 (Rs = 0.181, p = 0.014) and MMP-3 (Rs = 0.260, p = 0.0004) levels were positively correlated with HDL-cholesterol levels. TIMP-2 levels were negatively correlated with total cholesterol (Rs = -0.197, p = 0.007) and LDL-cholesterol (Rs = -0.168, p=0.022) levels. These results suggest that the circulating levels of MMPs and TIMPs are altered in patients with premature coronary atherosclerosis and that plasma lipoprotein cholesterol levels correlate with these, possibly as a result of the lipoprotein-vessel wall interactions.

High-density lipoprotein metabolism: molecular targets for new therapies for atherosclerosis.

New therapeutic approaches to the prevention and treatment of atherosclerotic cardiovascular disease (ASCVD) are needed. Plasma levels of high-density lipoprotein (HDL) cholesterol are inversely associated with risk of ASCVD. Genes involved in the metabolism of HDL represent potential targets for the development of such therapies. Because HDL metabolism is a dynamic process, the effect of a specific HDL-oriented intervention on atherosclerosis cannot necessarily be predicted by its effect on the plasma HDL cholesterol level. Based on available data in animal models, some gene products are candidates for pharmacologic upregulation, infusion, or overexpression, including apolipoprotein (apo)A-I, apoE, apoA-IV, lipoprotein lipase (LPL), ATP-binding cassette protein 1 (ABC1), lecithin cholesterol acyltransferase (LCAT), and scavenger receptor B-I (SR-BI). In contrast, some gene products are potential candidates for inhibition, including apoA-II, cholesteryl ester transfer protein (CETP), and hepatic lipase. The next decade will witness the transition from preclinical studies to clinical trials of a variety of new therapies targeted toward HDL metabolism and atherosclerosis.