Shotgun proteomics identification of proteins expressed in the Descemet's membrane of patients with Fuchs endothelial corneal dystrophy.

Fuchs endothelial corneal dystrophy (FECD) is a slowly evolving, bilateral disease of the corneal endothelium, characterized by an abnormal accumulation of extracellular matrix (ECM) in the basement membrane (Descemet's membrane, DM). This results in the formation of small round excrescences, called guttae, and a progressive disappearance of endothelial cells. In the intermediate stage, the numerous guttae create significant optical aberrations, and in the late stage, the loss of endothelial function leads to permanent corneal edema. The molecular components of guttae have not been fully elucidated. In the current study, we conducted shotgun proteomics of the DMs, including guttae, obtained from patients with FECD and revealed that 32 proteins were expressed only in the FECD-DMs but not in the DMs of control subjects. Subsequent enrichment analyses identified associations with multiple ECM-related pathways. Immunostaining of flat-mounted DMs confirmed that 4 of the top 5 identified proteins (hemoglobin α, SRPX2, tenascin-C, and hemoglobin γδεß) were expressed in FECD-DMs but not in non-FECD-DMs. Fibrinogen α was strongly expressed in FECD-DMs, but weakly expressed in non-FECD-DMs. We also demonstrated that matrix-assisted laser desorption ionization imaging mass spectrometry (MALDI-IMS) can display the in situ spatial distribution of biomolecules expressed in the DM, including the guttae.

Mass Spectrometry Imaging in Alzheimer's Disease.

Introduction: Amyloid-beta (Aß) pathology is the precipitating histopathological characteristic of Alzheimer's disease (AD). Although the formation of amyloid plaques in human brains is suggested to be a key factor in initiating AD pathogenesis, it is still not fully understood the upstream events that lead to Aß plaque formation and its metabolism inside the brains. Methods: Matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI) has been successfully introduced to study AD pathology in brain tissue both in AD mouse models and human samples. By using MALDI-MSI, a highly selective deposition of Aß peptides in AD brains with a variety of cerebral amyloid angiopathy (CAA) involvement was observed. Results: MALDI-MSI visualized depositions of shorter peptides in AD brains; Aß1-36 to Aß1-39 were quite similarly distributed with Aß1-40 as a vascular pattern, and deposition of Aß1-42 and Aß1-43 was visualized with a distinct senile plaque pattern distributed in parenchyma. Moreover, how MALDI-MSI covered in situ lipidomics of plaque pathology has been reviewed, which is of interest as aberrations in neuronal lipid biochemistry have been implicated in AD pathogenesis. Discussion: In this study, we introduce the methodological concepts and challenges of MALDI-MSI for the studies of AD pathogenesis. Diverse Aß isoforms including various C- and N-terminal truncations in AD and CAA brain tissues will be visualized. Despite the close relationship between vascular and plaque Aß deposition, the current strategy will define cross talk between neurodegenerative and cerebrovascular processes at the level of Aß metabolism.

Hornerin deposits in neuronal intranuclear inclusion disease: direct identification of proteins with compositionally biased regions in inclusions.

Neuronal intranuclear inclusion disease (NIID) is a neurodegenerative disorder, characterized by the presence of eosinophilic inclusions (NIIs) within nuclei of central and peripheral nervous system cells. This study aims to identify the components of NIIs, which have been difficult to analyze directly due to their insolubility. In order to establish a method to directly identify the components of NIIs, we first analyzed the huntingtin inclusion-rich fraction obtained from the brains of Huntington disease model mice. Although the sequence with expanded polyglutamine could not be identified by liquid-chromatography mass spectrometry, amino acid analysis revealed that glutamine of the huntingtin inclusion-rich fraction increased significantly. This is compatible with the calculated amino acid content of the transgene product. Therefore, we applied this method to analyze the NIIs of diseased human brains, which may have proteins with compositionally biased regions, and identified a serine-rich protein called hornerin. Since the analyzed NII-rich fraction was also serine-rich, we suggested hornerin as a major component of the NIIs. A specific distribution of hornerin in NIID was also investigated by Matrix-assisted laser desorption/ionization imaging mass spectrometry and immunofluorescence. Finally, we confirmed a variant of hornerin by whole-exome sequencing and DNA sequencing. This study suggests that hornerin may be related to the pathological process of this NIID, and the direct analysis of NIIs, especially by amino acid analysis using the NII-rich fractions, would contribute to a deeper understanding of the disease pathogenesis.

Establishment of a novel murine model of ischemic cardiomyopathy with multiple diffuse coronary lesions.

OBJECTIVES: Atherosclerotic lesions of the coronary arteries are the pathological basis for myocardial infarction and ischemic cardiomyopathy. Progression of heart failure after myocardial infarction is associated with cardiac remodeling, which has been studied by means of coronary ligation in mice. However, this ligation model requires excellent techniques. Recently, a new murine model, HypoE mouse was reported to exhibit atherogenic Paigen diet-induced coronary atherosclerosis and myocardial infarction; however, the HypoE mice died too early to make possible investigation of cardiac remodeling. Therefore, we aimed to modify the HypoE mouse model to establish a novel model for ischemic cardiomyopathy caused by atherosclerotic lesions, which the ligation model does not exhibit. METHODS AND RESULTS: In our study, the sustained Paigen diet for the HypoE mice was shortened to 7 or 10 days, allowing the mice to survive longer. The 7-day Paigen diet intervention starting when the mice were 8 weeks old was adequate to permit the mice to survive myocardial infarction. Our murine model, called the "modified HypoE mouse", was maintained until 8 weeks, with a median survival period of 36 days, after the dietary intervention (male, n = 222). Echocardiography demonstrated that the fractional shortening 2 weeks after the Paigen diet (n = 14) significantly decreased compared with that just before the Paigen diet (n = 6) (31.4±11.9% vs. 54.4±2.6%, respectively, P<0.01). Coronary angiography revealed multiple diffuse lesions. Cardiac remodeling and fibrosis were identified by serial analyses of cardiac morphological features and mRNA expression levels in tissue factors such as MMP-2, MMP-9, TIMP-1, collagen-1, and TGF-ß. CONCLUSION: Modified HypoE mice are a suitable model for ischemic cardiomyopathy with multiple diffuse lesions and may be considered as a novel and convenient model for investigations of cardiac remodeling on a highly atherogenic background.

Deletion of progranulin exacerbates atherosclerosis in ApoE knockout mice.

AIMS: Progranulin (PGRN) is a multifunctional protein known to be involved in inflammation. However, the relation between PGRN and atherosclerosis remains elusive. The aim of this study was to define the role of PGRN in the development of atherosclerosis. METHODS AND RESULTS: First, we checked the expression levels of PGRN in human atherosclerotic plaques. Immunohistochemical analysis showed that PGRN is strongly expressed in foam cells of atherosclerotic plaques. We also found that PGRN is expressed more abundantly in macrophages than in the smooth muscle cells of atherosclerotic lesions in ApoE(-/-) mice fed a high-fat diet for 12 weeks. Next, PGRN(-/-)ApoE(-/-) mice were generated to investigate the effect of PGRN on the development of atherosclerosis. PGRN(-/-)ApoE(-/-) mice exhibited severe atherosclerotic lesions compared with PGRN(+/+)ApoE(-/-) mice, despite their anti-atherogenic lipid profile. These results are partly due to enhanced expression of inflammatory cytokines, adhesion molecules, and decreased expression of endothelial nitric oxide synthase. In addition, lack of PGRN leads to accumulate excessive cholesterol in the macrophages and alter HDL-associated proteins. CONCLUSION: PGRN seems to be involved in the pathogenesis of atherosclerosis, possibly by various anti-atherogenic effects, including modulation of local and/or systemic inflammation.

Dietary manipulation and social isolation alter disease progression in a murine model of coronary heart disease.

BACKGROUND: Mice with a deficiency in the HDL receptor SR-BI and low expression of a modified apolipoprotein E gene (SR-BI KO/ApoeR61(h/h)) called 'HypoE' when fed an atherogenic, 'Paigen' diet develop occlusive, atherosclerotic coronary arterial disease (CHD), myocardial infarctions (MI), and heart dysfunction and die prematurely (50% mortality ~40 days after initiation of this diet). Because few murine models share with HypoE mice these cardinal, human-like, features of CHD, HypoE mice represent a novel, small animal, diet-inducible and genetically tractable model for CHD. To better describe the properties of this model, we have explored the effects of varying the composition and timing of administration of atherogenic diets, as well as social isolation vs. group housing, on these animals. METHODOLOGY/PRINCIPAL FINDINGS: HypoE mice were maintained on a standard lab chow diet (control) until two months of age. Subsequently they received one of three atherogenic diets (Paigen, Paigen without cholate, Western) or control diet for varying times and were housed in groups or singly, and we determined the plasma cholesterol levels, extent of cardiomegaly and/or survival. The rate of disease progression could be reduced by lowering the severity of the atherogenic diet and accelerated by social isolation. Disease could be induced by Paigen diets either containing or free of cholate. We also established conditions under which CHD could be initiated by an atherogenic diet and then subsequently, by replacing this diet with standard lab chow, hypercholesterolemia could be reduced and progression to early death prevented. CONCLUSIONS/SIGNIFICANCE: HypoE mice provide a powerful, surgery-free, diet-'titratable' small animal model that can be used to study the onset of recovery from occlusive, atherosclerotic CHD and heart failure due to MI. HypoE mice can be used for the analysis of the effects of environment (diet, social isolation) on a variety of features of cardiovascular disease.

Thyroid function influences serum apolipoprotein B-48 levels in patients with thyroid disease.

AIM: Apolipoprotein B-48 (apoB-48) is a major apolipoprotein of intestine-derived chylomicrons (CM) and CM remnants (CMR). Clinically overt hypothyroidism (OH) has been associated with premature and accelerated coronary atherosclerosis. To clarify the clinical significance of apoB-48 measurement in patients with thyroid disease, we investigated the correlations between the serum apoB-48 level and thyroid hormones. METHODS: From outpatients of Osaka University Hospital, patients with OH, subjects with subclinical hypothyroidism (SH) and subjects with normal thyroid function were collected and analyzed by measuring serum TSH, FT4 and FT3 levels. Serum apoB-48 levels were measured by a chemiluminescence enzyme immunoassay and the correlations with thyroid hormone levels or lipid profiles were assessed. These levels were compared among subjects with OH, SH and healthy controls. RESULTS: Serum apoB-48 level was correlated with TSH, total cholesterol (TC) and triglycerides (TG), but negatively with FT4 and FT3 level. LDL-C and HDL-C levels were not correlated with serum apoB-48 levels. Serum apoB-48 in patients with OH (7.4 ± 5.9 µg/mL) was significantly higher than in those with hyperthyroidism (5.1 ± 3.5 µg/mL; p<0.01) and normal subjects (4.7 ± 3.7 µg/mL; p<0.01), but decreased after levo-thyroxine replacement. ApoB-48, TG and TSH were significantly higher in SH subjects than normal subjects, suggesting that serum apoB-48 level depends on the thyroid function status, similar to TC, LDL-C and TG. CONCLUSION: Increased serum apoB-48 concentrations and CMR may contribute to the increased risk of atherosclerosis and premature coronary artery disease in the hypothyroid state.

Effect of probucol on antioxidant properties of HDL in patients with heterozygous familial hypercholesterolemia.

AIM: High density lipoprotein (HDL) has multi-antiatherogenic effects such as antioxidation and anti-inflammation, in addition to being a key mediator of reverse cholesterol transport. Probucol, known as a lipid lowering drug, is also a potent antioxidant, but it decreases serum HDL cholesterol (HDL-C) levels. To elucidate the effect of probucol on antioxidant properties of HDL, we investigated the function of HDL derived from patients with heterozygous familial hypercholesterolemia (FH) who have been treated with probucol. METHODS AND RESULTS: Probucol-treated FH patients (n=21) showed a 47% reduction of serum HDL-C levels compared to probucol-untreated FH patients (n=15). High performance liquid chromatography (HPLC) analysis revealed that probucol diminished HDL particle size compared to the non-treated group. Antioxidant capacity of HDL was evaluated by its effect to protect reference LDL from oxidation induced in the presence of an oxidizing agent, AAPH. The HDL derived from the probucol-treated group demonstrated a significantly prolonged time to start oxidation by 112%, decreased the maximum oxidation rate by 14%, and lowered the maximum concentration of conjugated dienes formation by 15%. Furthermore, HDL-associated paraoxonase 1 (PON1) activity, but not platelet-activating factor acetyl-hydrolase (PAF-AH) correlated with these measurements of HDL anti-oxidative activity. Treatment with probucol in vitro and inhibition of PON1 activity demonstrated that probucol in HDL particles and increase of PON1 activity might largely contribute to the increase of HDL anti-oxidative activity. CONCLUSION: Probucol reduced HDL-C levels and HDL particle size in patients with heterozygous FH, while it concomitantly enhanced HDL anti-oxidative properties, possibly through increasing PON1 activity.

Serum adiponectin level is correlated with the size of HDL and LDL particles determined by high performance liquid chromatography.

OBJECTIVE: Adiponectin (APN) improves insulin resistance and prevents atherosclerosis, and HDL removes cholesterol from atherosclerotic lesions. We have demonstrated that serum HDL-cholesterol (HDL-C) and APN concentrations are positively correlated and that APN accelerates reverse cholesterol transport (RCT) by increasing HDL synthesis in the liver and cholesterol efflux from macrophages. We previously reported that APN reduced apolipoprotein (apo) B secretion from the liver. It is well-known that insulin resistance influences the lipoprotein profile. In this study, we investigated the clinical significance of APN levels and insulin resistance in lipoprotein metabolism. MATERIAL/METHOD: We investigated the correlation between serum APN concentration, HOMA-R, the lipid concentrations and lipoprotein particle size by high-performance liquid chromatography (HPLC) in 245 Japanese men during an annual health checkup. RESULTS: Serum APN level was positively correlated with the cholesterol content in large LDL and HDL particles, but inversely correlated with the cholesterol content in large VLDL and small LDL particles. HOMA-R was negatively correlated with the cholesterol content in large LDL and HDL particles and positively correlated with the cholesterol content in large VLDL and small LDL particles. By multivariate analysis, APN was correlated with the particle size of LDL-C and HDL-C independently of age, BMI and HOMA-R. CONCLUSIONS: APN may be associated with the formation of both HDL and LDL particles, reflecting the enhancement of RCT and the improvement in TG-rich lipoprotein metabolism and insulin resistance.

Fasting serum apolipoprotein B-48 can be a marker of postprandial hyperlipidemia.

AIM: Postprandial hyperlipidemia (PH) is thought to be caused by the impaired postprandial metabolism of triglycerides (TG)-rich lipoproteins in both endogenous and exogenous pathways; however, there is no consensus. It is difficult to estimate the presence of PH without performing a time-consuming oral fat loading (OFL) test, so postprandial lipoprotein metabolism was analyzed by measuring the postprandial levels of apolipoprotein (apo) B-48 and apo B-100, and the correlation between postprandial TG increase and fasting apoB-48 levels was assessed to establish a good marker of PH without performing an OFL test. METHODS: Ten male normolipidemic subjects were loaded with a high-fat (HF, 1045 kcal) or standard (ST, 566 kcal) meal, and the lipids, apolipoproteins and lipoprotein profiles were analyzed after each meal. RESULTS: TG, apo B-48, remnant-like particles (RLP)-cholesterol and RLP-TG levels were increased and their levels were significantly higher after intake of the HF meal than the ST meal; however, there was no postprandial increase in apo B-100 and LDL-C levels. Postprandial increases in TG levels of CM, VLDL, LDL and HDL were significantly higher after intake of the HF meal than the ST meal. Fasting apo B-48 levels were strongly correlated with the incremental area under the curve of TG after intake of the HF meal, but not the ST meal. CONCLUSION: Postprandial TG increase was mainly due to increased CM and CM-R, but not VLDL. Measurement of fasting serum apo B-48 may be a simple and useful method for assessment of the existence of PH.

Molecular mechanisms of HDL-cholesterol elevation by statins and its effects on HDL functions.

Numerous large-scale clinical studies have revealed that the low-density lipoprotein cholesterol (LDL-C)-lowering effect of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase inhibitors (statins) prevents coronary heart disease (CHD). Statins have not only LDL-C-lowering effects but also high-density lipoprotein cholesterol (HDL-C)-elevating effects, which differ among statins. In this article, we discuss the molecular mechanisms of HDL-C elevation by statins and its effect on HDL functions. We summarize the reports to date on the effects of statins on various proteins, enzymes and receptors involved in reverse cholesterol transport (RCT), which is one of the protective systems against atherosclerosis. Since statins increase the synthesis of apolipoprotein A-I (ApoA-I) and HDL neogenesis in the liver, the HDL-C-increasing effect of statins may reflect RCT activation. Moreover, HDL has pleiotropic effects, including anti-inflammatory and anti-oxidative effects, as well as RCT. In the future, it may be necessary to assess the functions of HDL elevated by statins, and select statins based on differences in their effects in clinical practice.

Molecular mechanisms of ezetimibe-induced attenuation of postprandial hypertriglyceridemia.

AIM: Postprandial hypertriglyceridemia (PHTG) has been shown repeatedly to be associated with metabolic syndrome and atherosclerotic cardiovascular diseases. We have recently reported that ezetimibe inhibits PHTG in patients with type IIb hyperlipidemia. Ezetimibe was also reported to atten-uate PHTG in combination with low-dose statins in patients with obesity or metabolic syndrome. We reported CD36-deficient (CD36KO) mice as a new model for PHTG, in which the synthesis of chylomicron (CM) in the small intestines is enhanced. In the current study, we investigated the effect of ezetimibe on PHTG in this mouse model of metabolic syndrome. METHODS: Wild-type (WT) mice fed a western diet, and CD36KO mice fed a normal chow diet, respectively, were treated for 3 weeks with and without ezetimibe, followed by an evaluation of triglyceride (TG) concentrations by enzymatic method and by high performance liquid chromatogra-phy (HPLC) as well as those of and apolipoprotein (Apo) B-48 in plasma and intestinal lymph after oral fat loading with olive oil. Intestinal mucosa was also harvested to evaluate the transcriptional regulation of the genes involved in the intestinal production of ApoB-containing lipoproteins. RESULTS: Ezetimibe dramatically reduced PHTG in both WT and CD36KO mice. HPLC analysis of plasma showed that the decrease in TG content in CM and CM remnants-sized particles contributed to this suppression, suggesting that CM production in the small intestines might be reduced after ezetimibe treatment. Intestinal lymph was collected after oral fat loading in ezetimibe-treated and non-treated mice. Both TG content and ApoB-48 mass were decreased in ezetimibe-treated mice. The quantitative RT-PCR of intestinal mucosa showed down-regulation of the mRNA expression of FATP4 and ApoB in both groups along with FABP2, DGAT1, DGAT2 and SCD1 in WT mice at postprandial state after ezetimibe treatment. CONCLUSION: Ezetimibe alone reduces PHTG by blocking both the absorption of cholesterol and the intracellular trafficking and metabolism of long-chain fatty acids in enterocytes, resulting in the reduction of the formation of ApoB-48 which is necessary for the ApoB48-containing lipoprotein production in the small intestines.

Current therapy for patients with sitosterolemia--effect of ezetimibe on plant sterol metabolism.

Sitosterolemia is a rare, autosomal recessive inherited sterol storage disease associated with high tissue and serum plant sterol concentrations, caused by mutations in the adenosine triphosphate-bind-ing cassette (ABC) transporter ABCG5 or ABCG8 genes. Markedly increased serum concentration of plant sterols. such as sitosterol and campesterol, cause premature atherosclerosis and massive xanthomas. Hitherto known treatments for sitosterolemia, including a low-sterol diet, bile-salt binding resins, ileal bypass surgery and low density lipoprotein (LDL) apheresis have not yielded sufficient reduction of serum plant sterol levels and many patients show a sustained elevation of plant sterol levels, subsequently developing premature atherosclerotic cardiovascular diseases. Ezetimibe, an inhibitor of intestinal cholesterol absorption through its binding to Niemann-Pick C1-like 1 (NPC1L1), has been widely used for decreasing serum LDL-cholesterol levels in patients with hypercholesterolemia. Ezetimibe also reduces the gastrointestinal absorption of plant sterols, thereby also lowering the serum concentrations of plant sterols. This pharmacological property of ezetimibe shows its potential as a novel effective therapy for sitosterolemia. In the current review, we discuss the current therapy for patients with sitosterolemia and present two Japanese adolescent patients with this disease, one of whom underwent percutaneous coronary intervention for accelerated coronary atherosclerosis. Ezetimibe administration in addition to conventional drug therapy successfully reduced serum sitosterol levels by 51.3% and 48.9%, respectively, in the two patients, demonstrating ezetimibe as a novel and potent treatment agent for sitosterolemia that could work additively with conventional drug therapy.

Fenofibrate reduces postprandial hypertriglyceridemia in CD36 knockout mice.

AIM: Metabolic syndrome (MetS) and postprandial hypertriglyceridemia (PHTG) are closely related and both are associated with coronary heart disease. We have demonstrated that CD36 deficiency is prevalent in the genetic background of MetS and is accompanied by PHTG concomitantly with an increase in remnants and a decrease in high density lipoprotein cholesterol. These findings make CD36 knockout mice (CD36KO) an interesting model for evaluating PHTG in MetS. Fenofibrate was reported to reduce fasting and postprandial triglyceride (TG) levels in hypertriglyceridemic subjects with MetS. To define its mechanism, we investigated the effect of fenofibrate on PHTG in CD36KO. METHODS: Wild-type (WT) and CD36KO mice were fed chow diet and fenofibrate for two weeks. TG concentrations and lipoprotein profiles were assessed during fasting and in the postprandial state in plasma; intestinal mucosa and lymph were collected after oral fat loading for both treatment groups. RESULTS: Fenofibrate treatment markedly suppressed the postprandial TG response in CD36KO along with decreased apoB-48 levels in plasma. HPLC analysis depicted the decrease of TG content in chylomicrons (CM) and CM remnant-sized lipoproteins contributed to this suppression, suggesting that CM and CM remnant production in the intestines might be attenuated by fenofibrate. ApoB-48 and TG levels in intestinal lymph were markedly reduced after treatment. Intestinal mRNA expression of apoB was also reduced in the postprandial state after fenofibrate administration without affecting any other genes related to CM assembly and production. CONCLUSION: Fenofibrate reduces PHTG in CD36KO partially through attenuating intestinal CM production.

[Clinical significance of apolipoprotein B-48 (apoB-48) in patients with thyroid disease].

Apolipoprotein B-48 (apoB-48) is a constituent of chylomicrons and chylomicron remnants, and its serum concentration is thought to be one of the risk factors for atherosclerosis. Clinically overt hypothyroidism (OH) has been associated with accelerated and premature coronary atherosclerosis. In the current study, we measured the serum apoB-48 concentration in patients with hyperthyroidism and hypothyroidism. We also evaluated the correlations between serum apoB-48 and thyroid hormones, from which a clinical significance of apoB-48 measurement in thyroid disease was deduced. Serum apoB-48 concentration was measured by chemiluminescence enzyme immunoassay (CLEIA) and it correlated with thyroid stimulating hormone (TSH), total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) and triglycerides(TG), but negatively correlated with free thyroxine (FT4) and free triiodothyronine (FT3). In a cross-sectional study, serum apoB-48 concentrations were significantly higher in OH subjects (8.4 +/- 5.4 microg/ml) compared to those in 70 hyperthyroid subjects (5.0 +/- 3.9 microg/ml) and 50 normal subjects (6.3 +/- 4.9 microg/ml). After L-T4 replacement, serum apoB-48 concentrations were decreased in OH patients. However, these changes were smaller compared to those of TSH, FT4 and FT3. Serum apoB-48 levels and thyroid hormones and lipid profiles were measured in 31 SH patients and 34 normal subjects. Significant difference was noted in serum apoB-48, TG and TSH between patients with SH and normal. In conclusion, serum apoB-48 concentration depends on thyroid status like TC, LDL-C and TG. Thyroid hormone replacement therapy may reduce serum apoB-48 concentrations in patients with OH. Therefore, increased serum apoB-48 concentrations may contribute to the increased risk of atherosclerosis and premature coronary artery disease in the hypothyroid state.

Differential reactivities of four homogeneous assays for LDL-cholesterol in serum to intermediate-density lipoproteins and small dense LDL: comparisons with the Friedewald equation.

BACKGROUND: In routine clinical laboratory testing and numerous epidemiological studies, LDL-cholesterol (LDL-C) has been estimated commonly using the Friedewald equation. We investigated the relationship between the Friedewald equation and 4 homogeneous assays for LDL-C. METHODS: LDL-C was determined by 4 homogeneous assays [liquid selective detergent method: LDL-C (L), selective solubilization method: LDL-C (S), elimination method: LDL-C (E), and enzyme selective protecting method: LDL-C (P)]. Samples with discrepancies between the Friedewald equation and the 4 homogeneous assays for LDL-C were subjected to polyacrylamide gel electrophoresis and the beta-quantification method. RESULTS: The correlations between the Friedewald equation and the 4 homogeneous LDL-C assays were as follows: LDL-C (L) (r=0.962), LDL-C (S) (r=0.986), LDL-C (E) (r=0.946) and LDL-C (P) (r=0.963). Discrepancies were observed in sera from type III hyperlipoproteinemia patients and in sera containing large amounts of midband and small dense LDL on polyacrylamide gel electrophoresis. LDL-C (S) was most strongly correlated with the beta-quantification method even in sera from patients with type III hyperlipoproteinemia. CONCLUSIONS: Of the 4 homogeneous assays for LDL-C, LDL-C (S) exhibited the closest correlation with the Friedewald equation and the beta-quantification method, thus reflecting the current clinical databases for coronary heart disease.

Loss of cardiac microRNA-mediated regulation leads to dilated cardiomyopathy and heart failure.

RATIONALE: Heart failure is a deadly and devastating disease that places immense costs on an aging society. To develop therapies aimed at rescuing the failing heart, it is important to understand the molecular mechanisms underlying cardiomyocyte structure and function. OBJECTIVE: microRNAs are important regulators of gene expression, and we sought to define the global contributions made by microRNAs toward maintaining cardiomyocyte integrity. METHODS AND RESULTS: First, we performed deep sequencing analysis to catalog the miRNA population in the adult heart. Second, we genetically deleted, in cardiac myocytes, an essential component of the machinery that is required to generate miRNAs. Deep sequencing of miRNAs from the heart revealed the enrichment of a small number of microRNAs with one, miR-1, accounting for 40% of all microRNAs. Cardiomyocyte-specific deletion of dgcr8, a gene required for microRNA biogenesis, revealed a fully penetrant phenotype that begins with left ventricular malfunction progressing to a dilated cardiomyopathy and premature lethality. CONCLUSIONS: These observations reveal a critical role for microRNAs in maintaining cardiac function in mature cardiomyocytes and raise the possibility that only a handful of microRNAs may ultimately be responsible for the dramatic cardiac phenotype seen in the absence of dgcr8.

Impaired insulin secretion in four Tangier disease patients with ABCA1 mutations.

AIM: Tangier disease (TD), caused by deficiency of ATP-binding cassette transporter A1, is characterized by the absence of high density lipoprotein and the accumulation of cholesteryl esters in many tissues. Recently, it has been reported that ABCA1 is expressed in pancreatic beta cells and mice with specific inactivation of ABCA1 in beta cells showed markedly impaired insulin secretion, suggesting that ABCA1 deficiency may be involved in diabetes. The aim of the current study was to confirm these findings by the oral glucose tolerance test (OGTT) in human subjects with ABCA1 deficiency. METHODS AND RESULTS: Four Japanese patients with TD were investigated by OGTT with 75 g glucose. In all TD patients, the plasma glucose concentration after 30 min progressively increased, indicating a type 2 diabetic pattern; however the plasma insulin concentration did not respond well to glucose increase. The calculated insulinogenic index was significantly lower in TD patients than in non-diabetic controls (0.055+/-0.034 vs 0.775+/-0.538, mean+/-SD, p<0.05, respectively). CONCLUSIONS: Although the number of TD patients was very small in the current study, these observations indicated a possible mechanism that glucose-stimulated insulin secretion might be impaired in human TD patients with ABCA1 mutations. Taken together, ABCA1 may be involved in insulin secretion from pancreatic beta-cells.

Adiponectin prevents atherosclerosis by increasing cholesterol efflux from macrophages.

Plasma high density lipoprotein (HDL)-cholesterol levels are inversely correlated to the risk of atherosclerotic cardiovascular diseases. Reverse cholesterol transport (RCT) is one of the major protective systems against atherosclerosis, in which HDL particles play a crucial role to carry cholesterol derived from peripheral tissues to the liver. Recently, ATP-binding cassette transporters (ABCA1, ABCG1) and scavenger receptor (SR-BI) have been identified as important membrane receptors to generate HDL by removing cholesterol from foam cells. Adiponectin (APN) secreted from adipocytes is one of the important molecules to inhibit the development of atherosclerosis. Epidemiological studies have revealed a positive correlation between plasma HDL-cholesterol and APN concentrations in humans, although its mechanism has not been clarified. Therefore, in the present study, we investigated the role of APN on RCT, in particular, cellular cholesterol efflux from human monocyte-derived and APN-knockout (APN-KO) mice macrophages. APN up-regulated the expression of ABCA1 in human macrophages, respectively. ApoA-1-mediated cholesterol efflux from macrophages was also increased by APN treatment. Furthermore, the mRNA expression of LXRalpha and PPARgamma was increased by APN. In APN-KO mice, the expression of ABCA1, LXRalpha, PPARgamma, and apoA-I-mediated cholesterol efflux was decreased compared with wild-type mice. In summary, APN might protect against atherosclerosis by increasing apoA-I-mediated cholesterol efflux from macrophages through ABCA1-dependent pathway by the activation of LXRalpha and PPARgamma.

Increased lipid rafts and accelerated lipopolysaccharide-induced tumor necrosis factor-alpha secretion in Abca1-deficient macrophages.

Lipid rafts on the cell surface are believed to be very important as platforms for various cellular functions. The aim of this study was to know whether defective lipid efflux may influence lipid rafts on the cell surface and their related cellular functions. We investigated macrophages with defective lipid efflux from ATP binding cassette transporter A1-deficient (Abca1-KO) mice. Lipid rafts were evaluated by the following two novel probes: a biotinylated and protease (subtilisin Carlsberg)-nicked derivative of theta-toxin and a fluorescein ester of polyethylene glycol-derived cholesterol. Lipid rafts in Abca1-KO macrophages were increased, as demonstrated by both probes. Moreover, activities of nuclear factor kappaB, mRNA and intracellular distribution, and secretion of tumor necrosis factor-alpha (TNF-alpha) were examined after stimulation by lipopolysaccharides (LPSs). LPS-induced responses of the activation of nuclear factor kappaB and TNF-alpha were more prompt and accelerated in the Abca1-KO macrophages compared with wild-type macrophages. Modification of lipid rafts by cyclodextrin and nystatin corrected the abnormal response, suggesting an association between the increased lipid rafts and abnormal TNF-alpha secretion. We report here that Abca1-KO macrophages with defective lipid efflux exhibited increased lipid rafts on the cell surface and accelerated TNF-alpha secretion.