Preß1-high-density lipoprotein metabolism is delayed in patients with chronic kidney disease not on hemodialysis.

BACKGROUND: Preß1-high-density lipoprotein (HDL) is a lipid-poor cholesterol acceptor that is converted to lipid-rich HDL by lecithin-cholesterol acyltransferase (LCAT). In patients receiving hemodialysis, preß1-HDL metabolism is hampered even if HDL cholesterol is normal. Hemodialysis may affect preß1-HDL metabolism by releasing lipases from the vascular wall due to heparin. OBJECTIVES: We investigated whether preß1-HDL metabolism is delayed in patients with chronic kidney disease (CKD) who are not receiving hemodialysis. METHODS: We examined 44 patients with Stage 3 or higher CKD and 22 healthy volunteers (Control group). The patients with CKD were divided into those without renal replacement therapy (CKD group, n = 22) and those undergoing continuous ambulatory peritoneal dialysis (CAPD group, n = 22). Plasma preß1-HDL concentrations were determined by immunoassay. During incubation at 37°C, we used 5,5-dithio-bis (2-nitrobenzoic acid) (DTNB) to inhibit LCAT activity and defined the conversion halftime of preß1-HDL (CHTpreß1) as the time required for the difference in preß1-HDL concentration in the presence and absence of 5,5-DTNB to reach half the baseline concentration. RESULTS: The absolute and relative preß1-HDL concentrations were higher, and CHTpreß1 was longer in the CKD and CAPD groups than in the Control group. Preß1-HDL concentration was significantly correlated with CHTpreß1 but not with LCAT activity in patients with CKD and CAPD. CONCLUSION: Preß1-HDL metabolism is delayed in patients with CKD who are not on hemodialysis. This preß1-HDL metabolic delay may progress as renal function declines.

Soluble LR11 competes with amyloid ß in binding to cerebrospinal fluid-high-density lipoprotein.

BACKGROUND: LR11 is a member of the low-density lipoprotein (LDL) receptor family with high expression in neurons. Some cell surface LR11 is cleaved and secreted into the cerebrospinal fluid (CSF) as soluble LR11 (sLR11). Patients with Alzheimer's disease (AD), particularly apolipoprotein E4 carriers, have high CSF-sLR11 and low CSF-amyloid ß (Aß) concentrations. Therefore, we assessed whether sLR11 is bound to CSF-high-density lipoprotein (HDL) and whether sLR11 competes with Aß in binding to apoE in CSF-HDL. METHODS: We measured CSF-sLR11 concentrations (50 controls and 16 patients with AD) using enzyme immunoassay. sLR11 and apoE distribution in the CSF was evaluated using non-denaturing two-dimensional gel electrophoresis (N-2DGE). ApoE bound to sLR11 or Aß was identified using co-immunoprecipitation assay. RESULTS: CSF-sLR11 concentrations were higher in patients with AD than controls (adjusted for sLR11 using phospholipid). N-2DGE analysis showed that sLR11 and Aß comigrated with a large apoE-containing CSF-HDL. Moreover, fewer apoE was bound to Aß when a higher amount of apoE was bound to sLR11 in patients with AD who presented with ε4/4. CONCLUSION: sLR11 binds to CSF-HDL and competes with Aß in binding to apoE in CSF-HDL, indicating that sLR11 affects Aß clearance via CSF-HDL.

Assay system development to measure the concentration of sargramostim with high specificity in patients with autoimmune pulmonary alveolar proteinosis after single-dose inhalation.

During a clinical trial of a Saccharomyces cerviciae-derived recombinant human granulocyte-macrophage colony stimulating factor (rhGM-CSF), sargramostim, in patients with autoimmune pulmonary alveolar proteinosis (aPAP), we conducted a pharmacokinetic study of single-dose sargramostim inhalation. Several problems were encountered whereby sargramostim formed an immune-complex with GM-CSF autoantibodies (GMAbs) immediately after entering the body; thus, we could not measure the concentration of sargramostim using a commercial high sensitivity enzyme-linked immunosorbent assay (ELISA). Moreover, the ELISA could not discriminate inhaled sargramostim from intrinsic GM-CSF. To solve these problems, we developed a novel ELISA system with a capture antibody that is specific for sargramostim and a detection antibody capable of binding with GM-CSF. This system quantified the serum sargramostim concentration, but not E. coli-, CHO-, or HEK293T-derived human recombinant GM-CSF. Using this system, serum pharmacokinetics were estimated in five patients after inhalation of 250 µg sargramostim, with a mean Cmax of 9.7 ±â€¯2.85 pg/ml at a Tmax of 2 ±â€¯1.22 h.

Changes in apolipoprotein E-containing high-density lipoprotein (HDL) have little impact on HDL-cholesterol measurements using homogeneous assays in normolipidemic and dyslipidemic subjects.

BACKGROUND: High-density lipoprotein-cholesterol (HDL-C) is generally measured using several homogeneous assays. We aimed to clarify whether apolipoprotein E-containing HDL (apoE-HDL) subfractions are altered during storage, and if so, whether such changes affect the HDL-C concentration measured using homogeneous assays. METHODS: We stored serum from normolipidemic (n=32) and dyslipidemic (n=17) subjects at 4°C for up to 7days. ApoE-HDL subfractions were analyzed using native 2-dimensional gel (native 2D-gel) electrophoresis. HDL-C concentrations were determined using 2 precipitation and 4homogeneous assays. RESULTS: Native 2D-gel electrophoresis revealed variously sized apoE-HDL subfractions. After 4h incubation at 37°C, subfractions of smaller particles were converted into larger particles by lecithin:cholesterol acyltransferase (LCAT) activity. After 7days storage at 4°C, the smaller subfractions were decreased in the normolipidemic group, accompanying increases in larger subfractions, whereas changes in the respective subfractions varied among individuals in the dyslipidemic group. HDL-C concentrations were significantly lower after storage at 4°C in all assays, except that using Sekisui Medical's reagent. Therefore, changes in HDL-C concentration and apoE-HDL subfractions were independent of each other. CONCLUSION: ApoE-HDL subfractions change during storage, but these changes are not linked to those in HDL-C concentration measured using homogeneous assays.

Current smokers with hyperlipidemia lack elevated preß1-high-density lipoprotein concentrations.

BACKGROUND: Preß1-high-density lipoprotein (HDL) is an efficient acceptor of cell-derived free cholesterol, which is converted into lipid-rich HDL by lecithin-cholesterol acyltransferase. Previous studies have shown that preß1-HDL is significantly higher in individuals with hyperlipidemia. Preß1-HDL concentrations may be altered in smokers, who are at high risk for atherosclerosis. OBJECTIVE: The aim of the present study was to investigate the effect of smoking on preß1-HDL concentrations. METHODS: We measured the preß1-HDL concentration and lecithin-cholesterol acyltransferase-dependent conversion rate (CHTpreß1) in 74 men (39 nonsmokers and 35 smokers) using an immunoassay. RESULTS: The smoker and nonsmoker groups were further divided into normolipidemic and hyperlipidemic subjects. Among nonsmokers, the mean preß1-HDL concentration was 27% higher in hyperlipidemics than in normolipidemics (25.5 ± 6.7 vs 20.3 ± 4.6 mg/L apoAI, P < .01). In contrast, mean preß1-HDL concentrations did not differ between hyperlipidemic and normolipidemic smokers (19.9 ± 3.1 vs 22.4 ± 6.9 mg/L apoAI). We found a positive correlation between preß1-HDL concentration and CHTpreß1 in nonsmokers, but not in smokers. Smoking a single cigarette did not change preß1-HDL concentrations or CHTpreß1. Compared with nonsmokers, preß1-HDL concentrations were relatively low in hyperlipidemic smokers but not in normolipidemic smokers, and CHTpreß1 was not a significant determinant of preß1-HDL concentrations in smokers. CONCLUSION: Our findings suggest that smoking may be disadvantageous to individuals with hyperlipidemia because preß1-HDL metabolism is altered.

Selective evaluation of high density lipoprotein from mouse small intestine by an in situ perfusion technique.

The small intestine (SI) is the second-greatest source of HDL in mice. However, the selective evaluation of SI-derived HDL (SI-HDL) has been difficult because even the origin of HDL obtained in vivo from the intestinal lymph duct of anesthetized rodents is doubtful. To shed light on this question, we have developed a novel in situ perfusion technique using surgically isolated mouse SI, with which the possible filtration of plasma HDL into the SI lymph duct can be prevented. With the developed method, we studied the characteristics of and mechanism for the production and regulation of SI-HDL. Nascent HDL particles were detected in SI lymph perfusates in WT mice, but not in ABCA1 KO mice. SI-HDL had a high protein content and was smaller than plasma HDL. SI-HDL was rich in TG and apo AIV compared with HDL in liver perfusates. SI-HDL was increased by high-fat diets and reduced in apo E KO mice. In conclusion, with our in situ perfusion model that enables the selective evaluation of SI-HDL, we demonstrated that ABCA1 plays an important role in intestinal HDL production, and SI-HDL is small, dense, rich in apo AIV, and regulated by nutritional and genetic factors.

Ezetimibe decreases serum oxidized cholesterol without impairing bile acid synthesis in Japanese hypercholesterolemic patients.

OBJECTIVE: Cholesterol and diet-derived oxidized cholesterol are absorbed in the small intestine and eliminated by bile acids. We determined whether ezetimibe, a selective cholesterol absorption inhibitor, changes serum oxidized cholesterol levels. METHODS: We measured levels of plant sterols, cholesterol precursors, and oxysterols by gas chromatography-mass spectrometry in 47 hypercholesterolemics and 32 controls. Twenty-four hypercholesterolemics received 10 mg ezetimibe/day for 4 weeks. RESULTS: Plant sterols were 30-42% higher in hypercholesterolemics than in controls and positively correlated with low-density lipoprotein-cholesterol (LDL-C). Ezetimibe decreased plant sterols by 21-53%, but did not change bile acid synthesis markers. 7ß-hydroxycholesterol, a marker for non-enzymatic oxidation of cholesterol, was 66% higher in hypercholesterolemics than controls. Ezetimibe decreased 7ß-hydroxycholesterol levels by 15% regardless of LDL-C reduction. CONCLUSIONS: Ezetimibe decreases serum oxidized cholesterol generated by non-enzymatic reactions without impairing bile acid synthesis. Ezetimibe may maintain cholesterol excretion into bile and alleviate the diet-derived oxidative burden.

Clinical and genetic investigation of a Japanese family with cardiac fabry disease. Identification of a novel α-galactosidase A missense mutation (G195V).

Fabry disease is an X-linked lysosomal storage disorder caused by mutations of the α-galactosidase A gene (GLA), and the disease is a relatively prevalent cause of left ventricular hypertrophy mimicking idiopathic hypertrophic cardiomyopathy. We assessed clinically 5 patients of a three-generation family and also searched for GLA mutations in 10 family members. The proband had left ventricular hypertrophy with localized thinning in the basal posterior wall and late gadolinium enhancement (LGE) in the near-circumferential wall in cardiovascular magnetic resonance images and her sister had vasospastic angina pectoris without organic stenosis of the coronary arteries. LGE notably appeared in parallel with decreased α-galactosidase A activity and increased NT-pro BNP in our patients. We detected a new GLA missense mutation (G195V) in exon 4, resulting in a glycine-to-valine substitution. Of the 10 family members, 5 family members each were positive and negative for this mutation. These new data extend our clinical and molecular knowledge of GLA gene mutations and confirm that a novel missense mutation in the GLA gene is important not only for a precise diagnosis of heterozygous status, but also for confirming relatives who are negative for this mutation.

Profiles of inflammatory markers and lipoprotein subclasses in patients undergoing continuous ambulatory peritoneal dialysis.

BACKGROUND: Patients undergoing continuous ambulatory peritoneal dialysis (CAPD) often have inflammation and dyslipidemia that accelerate to atherosclerosis. This study aimed to evaluate chronic inflammation and dyslipidemia in CAPD patients. METHODS: We measured inflammatory markers and lipoprotein subclasses in 20 CAPD patients (12 men and 8 women, aged 59.5 ± 9.9 y) and 20 gender-matched controls. Lipoproteins were separated by high-performance liquid chromatography (HPLC) using an anion-exchange column. RESULTS: High-sensitivity C-reactive protein and serum amyloid A protein (SAA) were higher among CAPD patients vs. controls (1.6 ± 2.2 vs. 0.8 ± 1.2 mg/l, p<0.05; 11.9 ± 12.8 vs. 4.5 ± 2.4 mg/l). HPLC analysis revealed that chylomicron, VLDL, and IDL cholesterol levels were higher among CAPD vs. controls. In contrast, HDL cholesterol was lower among CAPD patients vs. controls. In the subgroup analysis, SAA levels were significantly lower among patients receiving CAPD for >3 y than among controls. However, IDL cholesterol was consistently higher among CAPD patients vs. controls. CONCLUSIONS: CAPD patients have chronic inflammation and dyslipidemia. IDL cholesterol is the only lipoprotein subclass that is consistently elevated regardless of CAPD duration. More attention should be paid to dyslipidemia in the management of the CAPD patients.

Statin therapy reduces inflammatory markers in hypercholesterolemic patients with high baseline levels.

AIM: Hypercholesterolemic patients with inflammation are at high risk for cardiovascular events. Statins exert anti-inflammatory action independent of their cholesterol-lowering action. This study sought to clarify whether statin therapy reduces inflammatory markers in hypercholesterolemic patients and to determine factors that predict the reduction in these markers. METHODS: Fasting concentrations of lipoproteins and inflammatory markers were measured in 54 hypercholesterolemic patients, and age- and gender-matched healthy volunteers. Carotid atherosclerosis was determined by ultrasonography. Blood samples were also analyzed in hypercholesterolemic patients after 4 weeks of statin therapy. RESULTS: The high-sensitivity C-reactive protein (hs-CRP) and serum amyloid A (SAA) protein concentrations did not differ between the two groups. Statin therapy reduced the median hs-CRP and SAA concentrations in hypercholesterolemic patients from 0.75 to 0.60 mg/L (p=0.05), and from 3.95 to 3.20 microg/mL (p=0.20), respectively. These reductions were significant for both markers, but only in subgroups with high baseline concentrations. Statins exhibited different results for hs-CRP and SAA in the presence of carotid atherosclerosis. CONCLUSIONS: Statin therapy reduces inflammatory markers in hypercholesterolemic patients, and this anti-inflammatory action is limited to patients whose inflammatory markers are elevated at baseline.

Prebeta1-HDL is elevated in the fasting state, but markedly reduced postprandially in poorly controlled type 2 diabetic patients.

BACKGROUND: Prebeta1-HDL is a minor HDL subfraction that is an initial acceptor of cellular free cholesterol. Prebeta1-HDL is elevated in hypertriglyceridemia, which is exaggerated with postprandial hyperglycemia. We investigated whether the prebeta1-HDL concentration changes postprandially in type 2 diabetic patients and blood glucose (BG) control reduces this change. METHODS: We examined 9 healthy controls and 20 diabetic patients with poor BG control. Seven blood samples (30 min before and 2 h after each meal, and at midnight) were obtained daily in the poor (poor-GC: n=20) and improved (imp-GC: n=11) glycemic control phases of diabetic patients after intensive insulin therapy and a low-calorie diet. RESULTS: The prebeta1-HDL concentration did not change postprandially in the controls. However, the fasting prebeta1-HDL concentration in the poor-GC phase was 28.3% higher than in the controls (25.4+/-6.8 vs 19.8+/-6.9 mg/l ApoAI, p<0.05) and decreased markedly after breakfast (20.9+/-7.7 mg/l ApoAI, p<0.01). In the imp-GC phase, the prebeta1-HDL concentration showed no morning surge, as in the controls. CONCLUSIONS: Type 2 diabetic patients in the poor-GC phase have high prebeta1-HDL levels in the morning, followed by a gradual reduction until midnight. BG control diminishes this postprandial change. Glucose metabolism may be involved in modulating reverse cholesterol transport in type 2 diabetic patients.

Low adiponectin state is associated with metabolic abnormalities in obese children, particularly depending on apolipoprotein E phenotype.

BACKGROUND: Adiponectin links obesity with insulin resistance, which causes various metabolic abnormalities including dyslipidaemia. Apolipoprotein E (apoE) phenotypes also affect lipoprotein profiles. We aimed to determine whether low adiponectin concentrations are associated with insulin resistance and downstream metabolic abnormalities in obese children. METHODS: We measured fasting concentrations of lipids, apoE, glucose, insulin and adiponectin, as well as anthropometric parameters, in 191 obese children aged 6-15 years. ApoE phenotypes were determined by isoelectric focusing. Boys (n = 79) and girls (n = 39) with apoE3/3 were classified into tertiles according to their adiponectin concentrations. Metabolic parameters, were compared among these three groups in boys and girls separately. RESULTS: The low adiponectin groups had higher median homeostasis model assessment of insulin resistance (HOMA-IR) than the middle and high adiponectin groups in both boys [5.3 (low) versus 3.1 (middle; P < 0.05) and 3.5 (high; P < 0.05)] and girls [5.0 (low) versus 4.4 (middle) and 3.0 (high; P < 0.05)]. However, only boys who were in the low adiponectin group exhibited significantly higher concentrations of blood pressure, triglycerides, LDL-cholesterol, and remnant-like particle-cholesterol, and lower concentrations of HDL-cholesterol compared with the middle or high adiponectin groups. CONCLUSION: Low adiponectin concentration is associated with insulin resistance in obese children. Furthermore, decreased adiponectin with E3/3 exhibited more prominent downstream metabolic abnormalities in obese boys than in obese girls.

Probucol markedly reduces HDL phospholipids and elevated prebeta1-HDL without delayed conversion into alpha-migrating HDL: putative role of angiopoietin-like protein 3 in probucol-induced HDL remodeling.

Probucol is a unique hypolipidemic agent that increases cholesteryl ester transfer protein (CETP) activity. Enhanced CETP-mediated conversion of high-density lipoprotein (HDL) partly explains the probucol-induced decrease in HDL cholesterol and increase in plasma prebeta1-HDL (native lipid-poor HDL) concentrations. However, HDL cholesterol is reduced in patients that are completely deficient in CETP. Angiopoietin-like protein 3 (ANGPTL3) is an endogenous suppressor of endothelial lipase that promotes the hydrolysis of HDL phospholipids and may generate prebeta1-HDL. To determine whether probucol decreases ANGPTL3 and HDL phospholipids while increasing prebeta1-HDL, we measured these parameters before and after a 4-week probucol treatment in 39 hypercholesterolemic patients and age- and sex-matched controls. The median ANGPTL3 had decreased from 143 to 113 microg/L by week 4 (p<0.05). High-performance liquid chromatography revealed that probucol decreased the phospholipid content of very large (13.5-15 nm) and large (12.1 nm) HDL particles predominantly by 65% (p<0.01) and 53% (p<0.001), respectively. The change in ANGPTL3, but not CETP mass, was positively correlated with that in large HDL phospholipids (r=0.455, p<0.05). The absolute and relative concentrations of prebeta1-HDL increased by 14% (p<0.01) and 60% (p<0.001), respectively. The conversion rate of prebeta1-HDL into alpha-migrating HDL by lecithin-cholesterol acyltransferase did not change significantly. In conclusion, probucol decreases plasma ANGPTL3 and HDL phospholipids while increasing prebeta1-HDL. We speculate that probucol induces HDL remodeling via an endothelial lipase-mediated pathway.

Serum amyloid A (SAA)-induced remodeling of CSF-HDL.

Inflammation is a risk factor for Alzheimer's disease. Serum amyloid A (SAA) is an acute phase protein that dissociates apolipoprotein AI (apoAI) from plasma HDL. In cerebrospinal fluid (CSF), the SAA concentration is much higher in subjects with Alzheimer's disease than in controls. CSF-HDL is rich in apoE, which plays an important role as a ligand for lipoprotein receptors in the central nervous system (CNS). To clarify whether SAA dissociates apoE from CSF-HDL, we added recombinant SAA to CSF and determined the apoE distribution in the CSF using native two-dimensional gel electrophoresis. We found that SAA dissociated apoE from CSF-HDL in a dose-dependent manner. This effect was more evident in apoE4 carriers than in apoE3 or apoE2 carriers. After a 24-h incubation at 37 degrees C, SAA continuously dissociated apoE from CSF-HDL. Amyloid beta (Abeta) fragments (1-42) were bound to large CSF-HDL but not to apoE dissociated by SAA. In conclusion, SAA dissociates apoE from CSF-HDL. We postulate that inflammation in the CNS may impair Abeta clearance due to the loss of apoE from CSF-HDL.

LCAT-dependent conversion rate is a determinant of plasma prebeta1-HDL concentration in healthy Japanese.

BACKGROUND: Prebeta1-HDL acts as a primary acceptor of cellular cholesterol. Prebeta1-HDL is converted into alpha-migrating high-density lipoprotein (HDL) by lecithin/cholesterol acyltransferase (LCAT). We examined whether the LCAT-dependent conversion rate of prebeta1-HDL is a determinant of the plasma prebeta1-HDL concentration in healthy Japanese. METHODS: We measured the conversion half time (CHT(prebeta1)), the time required for 50% of baseline prebeta1-HDL to be changed into alpha-migrating HDL by LCAT, in 100 healthy Japanese (47 men, 53 women, 22-88 years). RESULTS: Prebeta1-HDL concentration, as determined by immunoassay, was significantly lower in younger women (<50 years, n=24) than in older women (>or=50 years, n=29) (16.8+/-3.3 vs. 21.7+/-8.0 mg/l apolipoprotein AI (apoAI), p<0.01). There was no significant difference in prebeta1-HDL concentration between younger (n=24) and older (n=23) men (21.2+/-6.8 vs. 22.5+/-6.6 mg/l apoAI). The mean CHT(prebeta1) for all subjects was 47.4+/-13.0 min, and was not influenced by gender or age. Prebeta1-HDL concentration was positively correlated with CHT(prebeta1) in both men and women, suggesting that high prebeta1-HDL levels may reflect delayed conversion of prebeta1-HDL. CONCLUSION: LCAT-dependent conversion rate is a determinant of plasma prebeta1-HDL concentration in healthy Japanese. We speculate that prebeta1-HDL concentration may be used as a metabolic marker for HDL maturation.

T13M mutation of lecithin-cholesterol acyltransferase gene causes fish-eye disease.

BACKGROUND: Lecithin-cholesterol acyltransferase (LCAT) esterifies free cholesterol (FC) in plasma and plays a crucial role in the maturation of prebeta1-HDL (lipid-poor HDL) into alpha-migrating HDL (spherical HDL). Natural mutations of LCAT gene cause familial LCAT deficiency (FLD) or fish-eye disease (FED). The relationship between mutations and their phenotypes gives important clues to the functions of specific regions of LCAT. We investigated the first homozygous case with a substitution of threonine to methionine at codon 13 (T13M) of LCAT gene. METHODS: We evaluated LCAT activity, LCAT distribution among HDL subfractions and conversion of prebeta1-HDL to alpha-migrating HDL by native two-dimensional gel electrophoresis (N-2DGE). RESULTS: The proband had corneal opacity, severe hypo-alpha-lipoproteinemia, half-normal LCAT activity and near normal cholesteryl ester/total cholesterol (TC) ratio in plasma. These features were characteristic of FED. Plasma prebeta1-HDL concentration was near normal, but not converted to alpha-migrating HDL during 37 degrees C incubation. As expected, alpha-migrating HDL (especially large particles) was markedly reduced. In the immunoblot against LCAT, the small alpha-migrating HDL from the proband had much less LCAT in this patient than in controls. CONCLUSION: T13M mutation of LCAT gene causes FED.