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Obesity leads to the activation of pro-inflammatory pathways, resulting in a state of low-grade inflammation. Recently, several studies have shown that the exposure to lipopolysaccharide (LPS) could initiate and maintain a chronic state of low-grade inflammation in obese people. As the daily intake of food additives has increased substantially, the aim of the present study was to investigate a potential influence of food additives on the release of leptin, IL-6 and nitrite in the presence of LPS in murine adipocytes. Leptin, IL-6 and nitrite concentrations were analysed in the supernatants of murine 3T3-L1 adipocytes after co-incubation with LPS and the food preservatives, sodium sulphite (SS), sodium benzoate (SB) and the spice and colourant, curcumin, for 24 h. In addition, the kinetics of leptin secretion was analysed. A significant and dose-dependent decrease in leptin was observed after incubating the cells with SB and curcumin for 12 and 24 h, whereas SS decreased leptin concentrations after 24 h of treatment. Moreover, SS increased, while curcumin decreased LPS-stimulated secretion of IL-6, whereas SB had no such effect. None of the compounds that were investigated influenced nitrite production. The food additives SS, SB and curcumin affect the leptin release after co-incubation with LPS from cultured adipocytes in a dose- and time-dependent manner. Decreased leptin release during the consumption of nutrition-derived food additives could decrease the amount of circulating leptin to which the central nervous system is exposed and may therefore contribute to an obesogenic environment.

Objective HDL modifying effects of cholesteryl ester transfer protein (CETP) and hepatic lipase (LIPC) depend in part on each other. We studied associations of CETP -Taq1B and -514C>T- LIPC polymorphisms with hepatic mRNA levels, and their combined effects on plasma lipids and carotid atherosclerosis. Methods We genotyped the CETP -Taq1B and the -514C>T- LIPC polymorphisms in 67 obese women in whom hepatic CETP and LIPC transcript levels were determined as well as in 1549 participants of the Salzburg Atherosclerosis Prevention Program in Subjects at High Individual Risk (SAPHIR). Carotid atherosclerosis was assessed by intima-media thickness and extent of plaques (B-score) of the carotid arteries. Results In obese women, CETP -Taq1B and -514C>T- LIPC variant alleles were associated with reduced hepatic levels of CETP and LIPC mRNA, respectively. The CETP and LIPC polymorphisms accounted for 12.9 and 14.4% of the variability in respective transcripts. In the SAPHIR population, CETP -Taq1B showed independent effects on LDL diameter, HDL and LDL cholesterol, apolipoproteins AI and B and cholesterol/HDL cholesterol, while -514C>T- LIPC revealed independent effects on HDL cholesterol and apolipoprotein AI. The two polymorphisms displayed interactions at the level of HDL cholesterol. Compared to subjects carrying wild-type alleles at both loci, subjects homozygous for the CETP wild-type allele, but heterozygous for the LIPC polymorphism and subjects heterozygous for the CETP polymorphism, but homozygous for the LIPC wild-type allele showed an increased risk of carotid atherosclerosis (both P Conclusions CETP and LIPC polymorphisms influence the respective hepatic transcript levels, demonstrate interactions on HDL cholesterol and suggest that imbalances between CETP and LIPC activities may modulate the risk of carotid atherosclerosis.

HINTERGRUND: Ein spital-basiertes Screening Projekt (HSP) in Osterreich dokumentierte eine LDL-C Zielwert-Erreichung von 47% der Hochrisikopatienten (Ziel 100 mg/dl bei ca. 70% der Patienten eine Therapie-Intensivierung, meist durch Wechsel auf ein hochpotentes Statin. Bei LDL-C zwischen 70–100 mg/dl erfolgt jedoch weder bei Hoch- noch bei Hochstrisikopatienten eine Therapie-Intensivierung (< 5%). SCHLUSSFOLGERUNG: Sowohl in der Praxis als auch im Spital in Osterreich besteht, weitgehend parallel zu europaischen Analysen, weiterhin betrachtliches Verbesserungspotential in der Lipidzielwert-Erreichung bei kardiovaskularen Hoch- und Hochstrisikopatienten.

Eur J Clin Invest 2010; 40 (7): 616–622 Abstract Background The impact of cholesteryl ester transfer protein (CETP) in the development of atherosclerosis is a matter for ongoing debate. In this study, we analyse associations of CETP with cardiovascular endpoints in a cohort of patients with stable coronary artery disease (CAD). Design KAROLA is a prospective observational study of patients with CAD and a median follow-up of 8 years (n = 1132). CETP levels were measured using an enzyme-linked immunosorbent assay. Results Cholesteryl ester transfer protein levels were lower in men (P = 0·0016), positively correlated to low-density lipoprotein cholesterol, and inversely correlated to triglyceride levels (P

Background. Matrix metalloproteinases (MMPs) and their specific inhibitors (tissue inhibitor of metalloproteinases [TIMPs]), are involved in adipogenesis, angiogenesis and remodeling of extracellular matrix. MMPs and TIMPs have been shown to be associated with various diseases such as neurological disorders, malignancies and cardiovascular disease. MMPs and TIMPs are thought to play a major role in extensive reorganization of the adipose tissue in obesity. Methods and materials. To test whether significant weight loss alters circulating MMPs and TIMPs, 18 morbidly obese women, who underwent bariatric surgery for weight loss, were investigated before and one year after surgery in a prospective design study. Body composition, glucose and lipid metabolism parameters were determined in all study subjects before and after weight loss. Circulating MMP-2, -3, -7 and TIMP-1, -2 and -4 serum levels were measured using commercially available, enzyme-linked immunoassays. Results. Pronounced weight loss was accompanied by improvements in glucose homeostasis and lipid parameters. In the mean time MMP-2 and MMP-3, as well as TIMP-1, -2 and TIMP-4 concentrations were not affected by significant weight loss, and circulating MMP-7 increased significantly after bariatric surgery, although without reaching the standard levels as determined in 18, lean, healthy women. Conclusion. Our data indicate that reduced MMP-7 levels in obesity might be restored by significant weight loss, suggesting that the reorganization of adipose tissue in obesity might be partially reversible by weight reduction. We hypothesize that increased circulating MMP-7 might indicate enhanced adipocyte differentiation in subjects who had undergone bariatric surgery.

Aims: Vascular endothelial growth factor (VEGF) is a potent hypoxia-regulated angiogenic factor. Its soluble receptor soluble (s)Flt-1 binds VEGF with high affinity inhibiting the angiogenic function of VEGF. The role of circulating VEGF in atherosclerosis is unclear. Methods and results: In 909 healthy subjects (511 male, 398 female) from the Salzburg Atherosclerosis Prevention Program in Subjects at High Individual Risk (SAPHIR) we determined fasting plasma VEGF and sFlt-1 concentration, cardiovascular risk factors and carotid atherosclerosis. VEGF levels were lower and sFlt-1 levels higher in men than in women. VEGF and sFlt-1 showed a positive correlation. In the entire population VEGF correlated positively with age, BMI, insulin resistance, white blood cell and platelet count, C-reactive protein (CRP) and carotid intima media thickness (IMT). After adjustment for age, VEGF showed a weak positive correlation with BMI, liver enzymes, CRP and platelet count in males. In females VEGF correlated negatively with LDL-cholesterol and positively with insulin resistance and platelet count. After adjustment for age, no significant correlation with carotid atherosclerosis could be detected. Conclusion: Plasma VEGF and sFlt-1 are only weakly correlated with cardiovascular risk factors, suggesting that circulating VEGF levels do have only a minor impact on the development of atherosclerosis.

Adipocyte fatty acid binding protein (A-FABP) has been suggested to play an important role in fat metabolism linking obesity and the metabolic syndrome. Increasing A-FABP plasma levels were observed during greatest weight loss after bariatric surgery suggesting that A-FABP may indicate changes in fat mass in dynamic situations. As there are no data on weight gain, we investigated the effect of refeeding anorexic patients on body composition and A-FABP plasma levels. Parameters of glucose and lipid metabolism as well as plasma levels of leptin and A-FABP were prospectively assessed in 16 female patients with anorexia nervosa during inpatient weight restoration. Body composition was determined by multifrequency body impedance analysis. After 28 days, fat mass increased from 4.4 ± 2.5 kg at baseline to 5.5 ± 2.2 kg (P

This report describes studies in hyperlipidemic New Zealand White (NZW) rabbits investigating the impact of the liver-selective thyromimetic T-0681 on lipoprotein metabolism and the development of atherosclerosis. Prolonged treatment with T-0681 increased the hepatic expression of both LDL receptor and scavenger receptor class B, type I without affecting cholesteryl ester transfer protein activity. Upregulation of hepatic lipoprotein receptors was accompanied by a marked decrease of apolipoprotein B-containing lipoproteins, reflected by a 60% reduction of plasma cholesterol and a > 70% reduction of plasma triglyceride levels. Most importantly, T-0681 reduced the development of atherosclerosis by 80% in NZW rabbits on high-cholesterol chow. jlr Our data suggest that liver-selective thyromimetics, such as T-0681, may prove to be useful therapeutic agents against the development of atherosclerosis in humans.-Tancevski, I., A. Wehinger, E. Demetz, J. Hoefer, P. Eller, E. Huber, U. Stanzl, K. Duwensee, K. Auer, W. Schgoer, V. Kuhn, C. Fievet, F. Stellaard, M. Rudling, B. Foeger, J. R. Patsch, and A. Ritsch. The thyromimetic T-0681 protects from atherosclerosis. J. Lipid Res. 2009. 50: 938-944.

SummaryValproic acid (VPA) is an effective and widely used anticonvulsant, associated with metabolic adverse effects such as weight gain, hyperinsulinemia, hyperleptinemia and hypoadiponectinemia. The aim of this study was to evaluate the influence of VPA and topiramate (TPM) on adiponectin binding receptors, adipoR1 and adipoR2, in human liver cancer cells, HepG2. AdipoR1 but not adipoR2 gene expression was upregulated by VPA treatment. TPM did neither affect adipoR1 nor adipoR2 gene expression. Given the tight association between VPA treatment, metabolic side effects and the adipocytokine-axis, upregulation of adipoR1 possibly represents a favoured and insulin-sensitizing mechanism.

The aim of the study was to investigate the influence of severe hyperthyroidism on plasma high-density lipoprotein cholesterol (HDL-C). Recently, it was shown in mice that increasing doses of T3 up-regulate hepatic expression of scavenger receptor class B, type I, resulting in increased clearance of plasma HDL-C. Here, we show that severe hyperthyroidism in mice did not affect hepatic expression of scavenger receptor class B, type I, but reduced hepatic expression of ATP-binding cassette transporter 1, accompanied by a 40% reduction of HDL-C. The sterol content of bile, liver, and feces was markedly increased, accompanied by up-regulation of hepatic cholesterol 7α-hydroxylase, and ATP-binding cassette transporter 5, which is known to promote biliary sterol secretion upon dimerization with ATP-binding cassette transporter 8. Both control and hyperthyroid mice exerted identical plasma clearance of iv injected [3H]HDL-C, supporting the view that severe hyperthyroidism does not affect HDL-C clearance but, rather, its formation via hepatic ATP-binding cassette transporter 1.

Objective: Adiponectin is an adipocytokine secreted into circulation in three isoforms. The aim of the study was to investigate changes of adiponectin isoforms during profound weight loss and its relation to anthropomorphometric and metabolic parameters. Research Methods and Procedures: Thirteen severely obese female subjects were examined before and 1 year after surgical treatment. Total adiponectin was determined by radioimmunosorbent assay, and oligomer composition was detected by nondenaturing Western blot. Results: BMI decreased substantially (p < 0.001), which was associated with an increase of total adiponectin from 12.9 ± 5.9 to 14.3 ± 6.1 μg/mL (p = 0.055). Medium molecular weight (MMW) adiponectin increased from 7.5 ± 3.6 to 9.1 ± 4.1 μg/mL (p = 0.009), whereas high (HMW) and low molecular weight adiponectin remained unchanged. Δ values of total adiponectin correlated significantly with Δ values of anthropometric parameters. Similar correlations were found for Δ values of MMW (Δ weight: r2 = 0.4132, p = 0.0178; Δ BMI: r2 = 0.3319, p = 0.0393; Δ fat mass: r2 = 0.5202, p = 0.0054). Discussion: Thus, profound weight loss was associated with an increase in total adiponectin, which was mainly and consistently caused by increases in MMW adiponectin (p = 0.009). These changes result in a shift from low molecular weight to MMW and HMW adiponectin isoforms, which may be related to improvements in both anthropometric and metabolic parameters.

In the present study, we investigated the mechanisms by which resistin (100 nM, 1 h) affects glycogen synthesis in L6 skeletal muscle cells. The activity of glycogen synthase, the major enzyme in glycogen synthesis, is determined by both its covalent phosphorylation and allostery through intracellular glucose-6-phosphate. Covalent phosphorylation of glycogen synthase was not altered by resistin and, accordingly, phosphorylation of GSK-3α/β and Akt remained unchanged. The rate of glucose-6-phosphate formation, however, was decreased by resistin both in the absence and presence of insulin; in the absence of insulin, resistin decreased glucose-6-phosphate formation by reducing hexokinase type I activity without affecting glucose uptake; by contrast, in the presence of insulin, resistin decreased glucose-6-phosphate formation by reducing the Vmax of glucose uptake without changing hexokinase type I activity. In conclusion, short-term resistin incubation impairs glycogen synthesis by reducing the rate of glucose-6-phosphate formation involving, however, differential mechanisms in basal and insulin-stimulated states.

Objective. The B1B1 variant of the cholesteryl ester transfer protein (CETP) TaqIB polymorphism and high plasma CETP concentrations are associated with favourable angiographic outcomes in pravastatin-treated patients suffering from coronary artery disease (CAD). The purpose of the present study was to test whether CETP TaqIB genotypes and/or plasma CETP concentrations at baseline also predict clinical end-points in patients with CAD. Design. Prospective longitudinal observational study. Setting. Primary care doctors (n = 88) and hospitals (n = 7) in Austria. Subjects. A total of 1620 men and women with preexisting CAD were recruited and plasma lipids were determined at study entry. 1389 hypercholesterolaemic patients were included and 1002 patients completed the follow-up. Interventions. In all patients treatment with pravastatin was started and patients were followed up for 2 years. Main outcome measures. Cardiovascular events. Results. One hundred patients suffered at least one cardiovascular event. We observed significantly more events in patients within the lowest compared with the highest quartile of plasma CETP concentrations (odds ratio 3.20, CI95 1.65–6.23; P = 0.001, adjusted for known risk factors of CAD). No significantly different numbers of cardiovascular events were found between CETP TaqIB genotypes. Conclusions. Plasma CETP concentrations, but not CETP TaqIB genotypes, predict cardiovascular events in patients with CAD treated with pravastatin. Despite higher LDL cholesterol concentrations, high plasma CETP concentrations at baseline are associated with fewer cardiovascular events compared with low plasma CETP concentrations in CAD patients treated with pravastatin.

OBJECTIVE Low high-density lipoprotein cholesterol (HDL-C), hypertriglyceridemia, and small dense-low density lipoprotein (LDL) are key components of metabolic syndrome (MS). Cholesteryl ester transfer protein (CETP) mediates the transfer of triglycerides (TGs) from TG-rich lipoproteins to HDL and LDL particles in exchange for cholesteryl esters, leading to low HDL-C and small dense-LDL. The aim of this study was to investigate the role of CETP in subjects with MS. RESEARCH METHODS AND PROCEDURES In a cross-sectional cohort of 234 middle-aged men and 252 women randomly selected from the Salzburg Atherosclerosis Prevention Program in Subjects at High Individual Risk (SAPHIR) study, MS was diagnosed according to the National Cholesterol Education Program guidelines. CETP mass was determined by enzyme-linked immunosorbent assay and LDL size-by-gradient polyacrylamide gel electrophoresis. RESULTS Men and women with MS had lower HDL-C (45 +/- 7 vs. 58 +/- 13 and 48 +/- 10 vs. 71 +/- 14 mg/dL for men and women, respectively; p < 0.001 for all) and higher TG levels (222 +/- 71 vs. 98 +/- 54 and 167 +/- 67 vs. 90 +/- 35 mg/dL for men and women, respectively; p < 0.001 for all) than healthy subjects. LDL size was lower in subjects with MS (256 +/- 11 A vs. 267 +/- 11 A and 262 +/- 10 A vs. 273 +/- 8 A for men and women, respectively; p < 0.001 for all). CETP mass was higher in men with MS (1.87 +/- 0.78 vs. 1.40 +/- 0.65 mug/mL; p < 0.001) but not in women (1.74 +/- 0.79 vs. 1.62 +/- 0.62 mug/mL). CETP mass correlated inversely with LDL size in both men and women (r = -0.19, p < 0.01 and r = -0.13, p < 0.05 in men and women, respectively). DISCUSSION MS is associated with increased CETP mass in men. Increased CETP mass may be responsible for reduced HDL-C and reduced LDL particle diameter in MS.

Second-generation antipsychotic agents (SGAs) are increasingly replacing first-generation antipsychotic agents due to their superior activity against the negative symptoms of schizophrenia, decreased extrapyramidal symptoms and better tolerability. However, some SGAs are associated with adverse metabolic effects as significant weight gain, lipid disorders and diabetes mellitus. The pathogenesis of SGA-induced disturbances of glucose homeostasis is unclear. In vivo studies suggest a direct influence of SGAs on peripheral insulin resistance. To this end, we analyzed whether olanzapine might alter glycogen synthesis and the insulin-signaling cascade in L6 myotubes. Glycogen content was diminished in a dose- and time-dependent manner. Within the insulin-signaling cascade IRS-1 tyrosine phosphorylation was induced several fold by insulin and was diminished by preincubation with olanzapine. IRS-1-associated PI3K activity was stimulated by insulin three-fold in L6 myotubes. Olanzapine inhibited insulin-stimulated IRS-1-associated PI3K activity in a dose-dependent manner. Protein mass of AKT, GSK-3 and GS was unaltered, whereas phosphorylation of AKT and GSK-3 was diminished, and pGS was increased. Finally, we compared olanzapine with amisulpride, an SGA clinically not associated with the induction of diabetes mellitus. Glycogen content was diminished in olanzapine-preincubated L6 cells, whereas this effect was not observed under the amisulpride conditions. We conclude that olanzapine impairs glycogen synthesis via inhibition of the classical insulin-signaling cascade and that this inhibitory effect may lead to the induction of insulin resistance in olanzapine-treated patients.

SummaryPlatelet recruitment crucially depends on amplification systems provided by autocrine and paracrine factors such as adenosine diphosphate. In inflammatory states, consumption of coagulation proteins, such as antithrombin aggravates the procoagulant state. In this study, we report that platelets express synde-can-4, an antithrombin-binding cell surface heparan sulphate proteoglycan, whose ligation with antithrombin inhibits activated platelet-dependent superoxide anion release from neut-rophils by the limitation of adenosine diphosphate and adeno-sine triphosphate secretion in activated platelets. Adenosine triphosphate-induced platelet aggregation is reduced after treatment of platelets with antithrombin, which is reversed by blockade of syndecan-4. We further observed that antithrombin limits CD40 ligand expression in adenosine diphosphate-activated platelets and inhibits the shedding of syndecan-4 from activated platelets. Syndecan-4 appears to be directly involved in regulating platelet aggregation as anti-syndecan-4 antibody augments platelet aggregation. We suggest that antithrombin might exert beneficial effects in disseminated intravascular coagulation by reducing platelet activation, observed as inhibited CD40 ligand expression, syndecan-4 shedding, and adenosine diphosphate- and adenosine triphosphate-release from activated platelets with subsequent inhibition of neutrophil respiratory burst. From these data it is concluded that syndecan-4 may play important roles in the regulation of inflammatory effects of platelets.

Circulating monocytic cells may mediate neuroinvasion in transmissible spongiform encephalopathies by transporting prion protein (PrP) from sites of entry to the nervous system. Factors regulating monocyte-derived dendritic cell (DC) functions in neuronal tissue include neurogenic mediators, but their interactions with prion-infected DCs are unknown. Here, we report that neuropeptides regulate the interaction of DCs exposed to PrP 106–126 . Inhibition of neurokinin-1-receptors activation with neurokinin-1-receptor antagonist or antibody attenuates substance P-induced enhancement of DC migration induced by PrP 106–126 and prion-protein-induced DC maturation. Other neuropeptides arrest chemotaxis. Data support a priming role of the neuropeptide substance P in PrP 106–126 -induced migration of DCs involving neurokinin-1-receptors.

Background Increased vascularity of bronchial mucosa is closely related to the expression of angiogenic factors, which contribute to the pathogenesis of diseases such as asthma bronchiale. Objective Here we examine the effects of the angiogenic growth factors angiopoietin 1 and angiopoietin 2 on eosinophil function in vitro and possible involvement of the angiopoietin receptor Tie-2. Methods Eosinophil migration was studied by micropore filter assays. Signaling mechanisms required for angiopoietin-dependent migration were tested by using signaling enzyme blockers. Tie-2 mRNA and receptor expression on the cell surface of eosinophils was demonstrated in RT-PCR and by fluorescence-activated cell sorting analysis. Results Angiopoietin 1 significantly stimulated eosinophil chemotaxis via activation of phosphodiesterase, phosphatidylinositol 3′-kinase, and tyrosine kinases. The effect on eosinophil migration of angiopoietin 1 was reversed by an antibody against the Tie-2 receptor and by angiopoietin 2. Incubation of eosinophils with angiopoietin 1 abolished the chemotactic effects of vascular endothelial growth factor on human eosinophils via the Tie-2 receptor. Finally, Tie-2 expression by human eosinophils was demonstrated on the transcriptional and protein level. Conclusions Data suggest that angiopoietin 1 stimulates directed migration and possibly inhibits vascular endothelial growth factor–induced eosinophil chemotaxis via its Tie-2 receptor, which is expressed by eosinophils. Thus, angiopoietin 1 may play an important role in the modulation of eosinophilic inflammation.

Background—Induction of postnatal vasculogenesis, the mobilization of bone marrow–derived endothelial progenitor cells and incorporation of these cells into sites of blood vessel formation, is a well-known feature of angiogenic cytokines such as vascular endothelial growth factor. We hypothesized that the angiogenic neuropeptide secretoneurin induces this kind of neovascularization.Methods and Results—Secretoneurin induced mobilization of endothelial progenitor cells to sites of vasculogenesis in vivo in the cornea neovascularization assay. Progenitor cells were incorporated into vascular structures or were located adjacent to them. Systemic injection of secretoneurin led to increase of circulating stem cells and endothelial progenitor cells. In vitro secretoneurin induced migration, exerted antiapoptotic effects, and increased the number of these cells. Furthermore, secretoneurin stimulated the mitogen-activated protein kinase system, as shown by phosphorylation of extracellular signal–regulated kinase, and activated the protein kinase B/Akt pathway. Activation of mitogen-activated protein kinase was necessary for increase of cell number and migration, whereas Akt seemed to play a role in migration of endothelial progenitor cells.Conclusions—These data show that the angiogenic neuropeptide secretoneurin stimulates postnatal vasculogenesis by mobilization, migration, and incorporation of endothelial progenitor cells.

To further elucidate the role of scavenger receptor class B type I (SR-BI) in reverse cholesterol transport and in atherogenesis, we performed studies in the rabbit, an animal model displaying a lipoprotein profile similar to that of human, expressing cholesteryl ester transfer protein in plasma and having been demonstrated to be susceptible to atherosclerosis. In this report, we describe for the first time the isolation and characterization of rabbit cDNA fragments encoding SR-BI and scavenger receptor class B type II (SR-BII). Development of an isoform-specific Taqman Real Time PCR system and generation of isoform-specific polyclonal antibodies allowed us to measure SR-BI and SR-BII expression in various rabbit organs on mRNA and protein levels, respectively. We found the highest expression of SR-BI in adrenal gland, liver, and proximal intestine; lesser expression was found in appendix and spleen. Immunohistochemical staining of frozen sections showed SR-BI expression in the cortex but not in the medulla of adrenal gland. An increasing portal to central vein gradient of expression was found within the hepatic lobule. As shown in this report, identification and characterization of SR-BI expression in the rabbit affords a powerful tool to elucidate the role of SR-BI in cholesterol homeostasis and atherogenesis in human.

Objective: In obesity, plasma leptin is high and soluble leptin receptor (sOb-R) levels are low, resulting in a low fraction of bound leptin. The aim of this study was to investigate the influence of insulin resistance (IR) and the metabolic syndrome (MS) on sOb-R concentration and the bound-free ratio of leptin. Research Methods and Procedures: sOb-R, leptin levels, and homeostasis model assessment (HOMA) index for IR were determined in 76 middle-aged obese or overweight men. Results: Concentration of sOb-R and soluble receptor-bound fraction of leptin were lowest in the highest tertile of HOMA-IR. sOb-R and the bound-free ratio of leptin correlated with HOMA-IR, leptin concentration, and waist-to-hip ratio independently of age, BMI, and fat mass. Leptin and waist-to-hip ratio were the sole independent determinants of sOb-R concentration, and BMI, HOMA-IR, and visceral adipose tissue were independent determinants of the bound fractin of leptin. sOb-R concentration and the bound fraction of leptin decreased with increasing numbers of components of the MS, resulting in lower sOb-R concentration and a lower fraction of bound leptin in men with the MS. Discussion: IR and abdominal obesity are associated with low sOb-R concentration and low bound-free ratio of leptin independent of fat mass. Low sOb-R concentration and low bound-free ratio of leptin segregate with components of the MS. We suggest that low sOb-R levels and a low fraction of specifically bound leptin are markers of leptin resistance, which is independently associated with IR and abdominal obesity and may constitute an additional component of the MS.

PURPOSE OF REVIEW: Cholesteryl ester transfer protein facilitates the exchange of neutral lipids between HDL and apolipoprotein B containing lipoproteins, which hold powerful opposing roles as risk factors for coronary artery disease. The question as to whether cholesteryl ester transfer protein promotes or protects from atherosclerosis, however, has not been answered. RECENT FINDINGS: This review considers studies dealing with cholesteryl ester transfer protein variants and their effect on blood lipids in various metabolic and clinical settings. Other studies discussed deal with the association between the transfer protein and cardiovascular disease. Research on the biological activity of the cholesteryl ester transfer protein molecule is described including a first clinical study where pharmacological inhibition of the protein proved to be effective in raising HDL cholesterol. SUMMARY: Data concerning the potential marker role of cholesteryl ester transfer protein, although accumulating, are still inconclusive and, at present, not useful for clinical decision making. Inhibition of the protein was demonstrated to be feasible and appears to be promising.

Objective: Soluble leptin receptor (sOB-R) represents the main binding site for leptin in human blood. The aim of this study was to investigate the relationship between leptin and soluble leptin receptor and the bound/free ratio after pronounced weight reduction. Research Methods and Procedures: A total of 18 morbidly obese women participated in this prospective study. Subjects were examined for fat mass, leptin, and sOB-R concentrations before and 1 year after Swedish adjustable gastric banding. Results: Anthropomorphic measures displayed a significant reduction of body mass index [(42.9 ± 5.6 to 32.9 ± 6.0 kg/m2 (mean ± SD)]. Fat mass decreased from 56.3 ± 9.0 to 33.9 ± 12.5 kg. Plasma leptin concentration decreased from 44.6 ± 18.0 to 20.0 ± 13.1 ng/mL (p < 0.001), whereas the sOB-R levels increased from 11.1 ± 3.6 to 16.6 ± 6.0 U/mL after weight-reducing surgery. Thus, the sOB-R bound fraction of leptin increased from 7% to 33%. Discussion: This work demonstrates a relationship between weight loss, leptin, and sOB-R concentrations in vivo. During weight loss, leptin levels decreased, whereas sOB-R levels and the receptor bound fraction of leptin increased. Thus, sOB-R may negatively regulate free leptin.

BACKGROUND: The purpose of the investigation presented here was to study the effects of insulin therapy in type 2 diabetes mellitus (type 2 DM) not only on glycemic control but also on other components of the metabolic syndrome, including lipid metabolism, blood pressure, and body weight. METHODS: Twelve patients with type 2 DM were studied before and after replacement of sulphonylurea treatment with insulin for 4 months. RESULTS: Insulin therapy resulted in a significant decrease in fasting glucose levels by 26%; glycated hemoglobin decreased by 17% and fructosamine values by 19%. With insulin treatment, fasting plasma triglyceride levels decreased by 28% and total HDL cholesterol and HDL(3) cholesterol increased by 17 and 11%, respectively. Low-density lipoprotein (LDL) cholesterol showed no significant change. The magnitude of postprandial lipemia after ingestion of a standard fatty meal decreased by 38%. Insulin treatment was also accompanied by a 21% increase in lipoprotein lipase (LPL) activity in postheparin plasma and by a 20% increase in cholesteryl ester transfer protein (CETP) activity. Hepatic lipase activity was not changed significantly with insulin. Mean BMI decreased from 28.5+/-4.2 to 28.0+/-3.1 kg/m(2) (P=0.02), which is in keeping with the finding that peripheral insulin levels did not increase and which can be explained by the fact that the insulin regimen was combined with dietary counseling. Accordingly, blood pressure showed no significant change. CONCLUSION: Our study demonstrates that judicious replacement of sulfonylurea treatment with insulin therapy, together with dietary counseling, can result in a simultaneous improvement in the major stigmata of the metabolic syndrome, i.e. a significant improvement in glycemic control and lipid metabolism without unfavorable effects on body weight and blood pressure.

Phospholipid transfer protein (PLTP) plays an important role in plasma lipoprotein metabolism. However, PLTP is expressed in a wide range of tissues suggesting additional local functions. To analyze the tissue distribution of PLTP in an animal with high-level expression of the structurally and functionally related CETP, we have cloned the full-length cDNA of rabbit PLTP (1,796 bp). Rabbit PLTP cDNA shows high homology to human, murine, and porcine PLTP cDNA, averaging 86.1%, 80.4%, and 86.1%, respectively. Interestingly, the C-terminus contains a unique seven amino acid insertion not found in previously characterized mammalian PLTPs. In clear contradistinction to human PLTP, rabbit PLTP mRNA was prominent in brain. In situ hybridization studies revealed specific, high-level synthesis of PLTP mRNA in choroid plexus and ependyma, the organs responsible for production of cerebrospinal fluid. Consistent with these findings, PLTP activity in cerebrospinal fluid amounted to 23% ± 3% of that in rabbit plasma. In contrast, neither CETP mRNA nor CETP activity were detectable in rabbit brain. A role of PLTP in the central nervous system could involve some of its actions previously established in vitro, like proteolysis of apolipoproteins, and be physiologically relevant for neurodegenerative disorders such as Alzheimer's disease.—Gander, R., P. Eller, S. Kaser, I. Theurl, D. Walter, T. Sauper, A. Ritsch, J. R. Patsch, and B. Föger. Molecular characterization of rabbit phospholipid transfer protein: choroid plexus and ependyma synthesize high levels of phospholipid transfer protein. J. Lipid Res. 2002. 43: 636–645.

AIM: Phospholipid transfer protein (PLTP) and cholesteryl ester transfer protein (CETP) are key enzymes in lipoprotein metabolism facilitating the transfer and exchange of cholesteryl esters, triglycerides and phospholipids between lipoproteins. In the study presented here, we investigated the influence of two hormones-the adipocyte-derived hormone leptin as well as insulin on the hepatic secretion of both, PLTP and CETP. METHODS: PLTP activity and CETP concentration-measured by exogenous substrate assay and enzyme-linked immunosorbent assay-were determined in supernatant of human hepatoma cell line HepG2 after single or combined exposure to leptin and insulin at physiological and supraphysiological concentrations, respectively. Messenger-RNA of PLTP and CETP was quantified by Northern blot analysis. RESULTS: Leptin suppressed PLTP activity and CETP-concentration by up to 33% and 23%, respectively. Insulin also suppressed PLTP activity by up to 11% and CETP-concentration by up to 16%. In combination, the two hormones had additive suppressive effects for both, PLTP activity and CETP-concentration. Northern blot analysis showed no difference in m-RNA levels after exposure to leptin or insulin. CONCLUSIONS: Leptin and insulin, both known to increase with body fat mass, suppress production of PLTP and CETP in HepG2 cells. When extrapolated to the in vivo situation, this suppressive effect may constitute a mechanism counteracting the potentially harmful action of lipid transfer proteins, particularly reduction of HDL-cholesterol, in conditions frequently associated with increased plasma triglyceride levels such as obesity and insulin resistance.

Abstract A patient is described who exhibited, despite excessively high postprandial triglyceride levels, high levels of HDL cholesterol. Measurement of CETP activity and mass in the patient’s plasma showed values of less than 5% and 2%, respectively, of a normolipidemic plasma pool. The CETP cDNA of the patient exhibited a mutation (T → G), turning codon 57 (TAT) of exon 2 into a stop codon (TAG) and abolishing a, Xcm I restriction site. Digestion of directly amplified CETP cDNA from the patient with Xcm I indicated the exclusive presence of CETP cDNA containing the mutation. Analysis of the corresponding region of the CETP gene indicated the patient to be heterozygous for the nonsense mutation at codon 57, a finding that can only be explained by the presence of a null allele in addition to the allele with the nonsense mutation. The combination of TG intolerance of uncertain cause, together with CETP deficiency due to a novel mutation, produced the paradoxical constellation—high levels of HDL cholesterol (172 mg/dL) associated with a high postprandial lipemia of 1460 mg triglycerides/dL.8 hours—and provided further insight into the role of CETP as mediator between pools of triglycerides and cholesteryl esters in plasma.

We developed a gel filtration assay for the determination of glycogen synthase activity in cultured cells or tissue homogenates. Compared to the commonly used filter paper assay, the gel filtration assay resulted in a more than 5-fold reduction of background levels leading to an – at least – twofold increase in precision. These benefits allow the gel filtration method to detect differences of ±5% in enzyme activity out of 300 μg total cell protein. In addition to high precision and sensitivity, the method's additional salient advantages include lesser expenditure of time and labour and reduced exposure time of the personnel to radioactivity.

Abstract Hepatic lipase has a demonstrated dual role in plasma lipid transport in that it participates in the removal of remnants of triglyceride-rich lipoproteins from the circulation and in the metabolism of plasma HDL. The study presented here investigated the substrate properties for hepatic lipase of HDL differing in density and apolipoprotein (apo) composition. Rates of fatty acid liberation were twofold higher in HDL 2 compared with the respective HDL 3 subspecies. Within each density class, enzyme-catalyzed fatty acid release was nearly twofold higher from HDL containing apoA-II compared with HDL devoid of apoA-II. When native HDL 3 devoid of apoA-II was reconstituted with dimeric apoA-II in vitro, rates of fatty acid liberation in reconstituted particles were similar to those in native HDL 3 containing apoA-II. HDL containing apoA-II competed more effectively with small VLDL for binding of hepatic lipase than HDL devoid of apoA-II. HDL 3 , particularly apoA-II–containing HDL 3 , reduced lipolysis of triglyceride and total fatty acid liberation in small VLDL. We conclude that the substrate properties of HDLs for hepatic lipase are influenced by both their size and apoA-II content. Moreover, size as well as apoA-II content may indirectly affect remnant clearance.

Association of apo(a)/Lp(a) with triglyceride-rich lipoproteins (TGR-Lps) is determined by different factors that are poorly understood. Some previous studies suggested that apo(a) in TGR-Lps may affect the atherogenicity of the TGR particles. To study whether there are any peculiarities in postprandial (pp) Lp(a) metabolism, we have determined apo(a) phenotypes and Lp(a) concentrations in 46 subjects with coronary heart disease (CHD) and in six normolipidemic individuals at different time points (4, 6 and 8 h) following an oral fat tolerance test. While mean triglyceride concentration reached its maximum 6 h after a standardized fat meal, no change in total cholesterol and in mean Lp(a) plasma concentration was detected at any time point after the fat load. In 6 normolipidemic probands and in 8 patients with CHD, who were matched for apo(a) phenotype, lipoprotein levels, age and body weight, we followed the distribution of apo(a) in plasma density gradient fractions in the fasting and pp state. In the CHD patients a significant larger percentage of apo(a) reactivity was detected in TGR-Lps in the pre- as well as in the postprandial state, compared to control subjects. The fat intake did not induce a significant change of apo(a) reactivity in the TGR-Lp fractions in both groups. The apo(a) isoform-size and the Lp(a) plasma concentration in the fasting state had no influence on the individual variation of the Lp(a) concentration in pp TGR-Lp fractions. Our results provide evidence that TGR-Lp fractions of CHD patients are enriched in apo(a) reactivity compared to healthy controls, but do not support the hypothesis that Lp(a) acts atherogenically through a pp increase of its plasma concentration.

Postprandial hyperlipidaemia is a risk factor for atherosclerosis in multiple vascular beds, independently of high-density lipoprotein (HDL) cholesterol. An increased level of HDL cholesterol is a strong indicator of a low risk of atherosclerosis. Exercise decreases postprandial lipaemia and, in turn, increases levels of HDL cholesterol. The favourable effects of exercise on lipoprotein metabolism, particularly evident in the postprandial state, may thus help to decrease susceptibility to atherosclerosis in exercise-trained people.

Chemically or biologically modified low-density lipoproteins (LDL) but not native unmodified LDL lead to foam cell formation in monocyte-derived macrophages. Since the magnitude of postprandial lipemia after a challenge test seems to be associated with coronary artery disease, we tested the hypothesis that in the course of postprandial lipemia, LDL appear in plasma that are capable of leading to foam cell formation even without prior modification. We incubated the macrophage-like cell line P388 with unmodified postabsorptive and postprandial LDL from 17 healthy donors and measured the cellular cholesterol and triglyceride contents and amounts of exogenous [14C]oleic acid incorporated into the cholesteryl ester fraction. Postprandial LDL induced a significantly more pronounced cholesteryl ester accumulation than did postabsorptive LDL (477 +/- 286% versus 212 +/- 173%, respectively; P < .003). The increase in cellular total cholesterol was significantly higher as a result of cell incubation with postprandial LDL (107 +/- 61%) than with postabsorptive LDL (54 +/- 40%, P < .003), whereas no increase in triglyceride content was observed (P < .589) in either case. After CuSO4 incubation and incubation with P388 cells, postprandial LDL revealed more thiobarbituric acid-reacting substances than did postabsorptive LDL (55 +/- 10 versus 28 +/- 9 nmol/mg protein, P < .018; 28 +/- 4 versus 20 +/- 3 nmol/mg protein). The increase in cellular cholesteryl ester synthesis caused by postprandial LDL was reduced by more than 50% when lipoproteins and cells were incubated in the presence of ascorbic acid (P < .007).(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma triglyceride (TG)-rich lipoproteins are related to high density lipoprotein (HDL)-cholesterol and risk of coronary artery disease (CAD). Two major hypotheses on the role of HDL in the development of CAD have been proposed: a 'causalist' view assigns a protective effect against atherosclerosis to HDL and a 'non-causalist' view states that HDL do not interfere directly with development of atheroma but reflect metabolism of TG-rich lipoproteins. HDL exist as two major subfractions: small, lipid-poor, dense HDL3, and larger, lipid-rich, less dense HDL2, with variable levels of total-HDL cholesterol. Rapid lipolysis of TG-rich lipoproteins produces increased lipid uptake, formation of HDL2 and may protect the arterial wall; delayed lipolysis increases transfer of TG from TG-rich lipoproteins into HDL. Cholesteryl ester transfer protein (CETP) catalyzes lipid exchange and may be the mechanism for switching 'good cholesterol' into 'bad cholesterol'. According to this view, the driving force for the switch is the metabolism of TG-rich lipoproteins. Rapid clearance of TG-rich lipoproteins promotes formation of HDL2, low levels of TG-rich lipoproteins prevent transfer of HDL-cholesteryl esters into TG-rich lipoproteins keeping HDL-cholesterol high. The net effect is antiatherogenic. Accumulation of TG-rich lipoproteins leads to transfer of cholesteryl esters from HDL into lipoprotein fractions associated with high CAD risk.

The short-term effects of prolonged intense exercise on plasma lipid transport parameters including cholesterol, triglycerides (TGs), low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and its subfractions HDL 2 cholesterol and HDL 3 cholesterol, on apolipoproteins (apos) A-I, A-II, and B, and on mass and activity of cholesteryl ester transfer protein (CETP) were studied in eight male endurance-trained athletes over the first week after a bicycle marathon. CETP mass concentration in plasma was quantified by a newly developed immunoradiometric assay (IRMA). Plasma concentrations of cholesterol, TGs, LDL cholesterol, apo B, CETP, and cholesteryl ester transfer activity (CETA) were significantly reduced in the recovery period compared with pre-exercise values (cholesterol by 20%, P P P P P P 2 cholesterol, in contrast, were significantly increased in the post-exercise period (HDL cholesterol by 12%, P 2 cholesterol by 96%, P 3 cholesterol showed a tendency to decrease in the late recovery period (by 8%, NS). Although changes in cholesterol, triglycerides, HDL cholesterol, LDL cholesterol, apo B, and CETP mass and activity were already evident in the early recovery period, HDL 2 cholesterol showed a delayed response, reaching its maximum 72 hours after initiation of exercise. In addition, significant increases in plasma levels of apo A-I and A-II were found 8 days after the marathon (by 5%, P P 2 cholesterol may be explained at least in part by the decrease in CETP after short-term exercise.

Objective: The enzyme 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase catalyses the rate-limiting step in cholesterol biosynthesis. Until now, there has been no evidence for a possible correlation between HMG-CoA reductase activity and human liver disease. The objective of this study was to test whether HMG-CoA reductase activity is altered in cryptogenic fatty liver disease. Method: We measured this enzyme activity in liver tissue of 20 patients undergoing routine transcutaneous biopsy of the liver (10 patients with cryptogenic fatty liver disease, three with alcoholic fatty liver disease, two with chronic hepatitis and five with normal histology)

To gain insight into metabolic determinants of high density lipoproteins (HDL) containing apolipoproteins A-I and A-I1 (LpA-I/A-11) and those containing A-I, but devoid of A-I1 (LpA-I), the plasma concentration of LpA-I and LpA-I/A-I1 wi- thin the HDLz and HDL3 density spectrum was measured in 14 normolipidemic male subjects on a standardized diet. Apolipoprotein plasma concentrations of HDL subspecies were compared with the magnitude of postprandial lipemia, activities of lipoprotein lipase and hepatic lipase in postheparin plasma, plasma 1ecithin:cholesterol acyltransferase (LCAT) activity, and cholesteryl ester transfer protein (CETP) mass. Plasma levels of LpA-I/A-I1 were 2.5 times higher than levels of LpA-I (123 + 20 vs. 48.3 f 22.1 mg protein/dl) and the partition of LpA-I and LpA-I/A-I1 between HDLz and HDL3 differed in that the proportion of LpA-I associated with HDLZ was greater than that of LpA-I/A-I1 (23 f 19 vs. 6 6%, P < 0.002). With increas- ing levels of HDLZ, the proportion of LpA-I in HDLZ increased (P < 0.002). Furthermore, levels of LpA-I and LpA-I/A-I1 were strongly correlated within the HDLZ, but not within the HDLS density region. Plasma levels of LpA-I, but not LpA-I/A-11, were inversely correlated with the magnitude of postprandial lipemia. However, activities of lipoprotein lipase and hepatic lipase tended to show stronger associations with the partition of LpA- I/A-I1 between HDLz and HDL3 than with that of LpA-I. Wi- thin the HDL,, but not the HDLZ density spectrum, LpA-I/A-I1 exhibited a positive association with plasma LCAT activity, while LpA-I displayed an inverse association with plasma CETP mass. I These results are consistent with differences in sub- strate properties of LpA-I and LpA-I/A-I1 for lipoprotein- modifying enzymes and imply different, but overlapping meta- bolic pathways of LpA-I and LpA-I/A-11.-Mowri, H-O., J. R. Patsch, A. Ritsch, B. Foger, S. Brawn, and W. Patsch. High density lipoproteins with differing apolipoproteins: relationships to postprandial lipemia, cholesteryl ester transfer protein, and activities of lipoprotein lipase, hepatic lipase, and leci- thin:cholesterol acyltransferase. J. Lipid Res. 1994. 35: 291-300.

Highlights ► The pathophysiological link between NAFLD and hepatic insulin resistance is unknown. ► We studied the effect of postprandial lipoproteins on hepatic insulin sensitivity. ► Postprandial lipoproteins cause liver steatosis and hepatic insulin resistance. ► We characterize the underlying molecular mechanisms. ► Postprandial lipoproteins are a link between NAFLD and hepatic insulin resistance., Non-alcoholic fatty liver disease (NAFLD) is associated with hepatic insulin resistance with the molecular basis of this association being not well understood. Here we studied the effect of hepatic triglyceride accumulation induced by postprandial triglyceride-rich lipoproteins (TGRL) on hepatic insulin sensitivity in HepG2 cells. Incubation of HepG2 cells with purified TGRL particles induced hepatocellular triglyceride accumulation paralleled by diminished insulin-stimulated glycogen content and glycogen synthase activity. Accordingly, insulin-induced inhibition of glycogen synthase phosphorylation as well as insulin-induced GSK-3 and AKT phosphorylation were reduced by TGRL. The effects of TGRL were dependent on the presence of apolipoproteins and more pronounced for denser TGRL. Moreover, TGRL effects required the presence of heparan sulfate-proteoglycans on the cell membrane and lipase activity but were independent of the cellular uptake of TGRL particles by receptors of the LDL receptor family. We suggest postprandial lipemia to be an important factor in the pathogenesis of NAFLD.

Cholesteryl ester transfer protein (CETP) catalyzes the transfer of neutral lipids among plasma lipoproteins and in this way plays a prominent role in cholesterol metabolic routing and, thus, probably for atherosclerosis. Studies of this important protein in various clinical settings require the ability to accurately quantify CETP in plasma. In order to gain access to such a capability, an immunoradiometric assay (IRMA) for quantification of CETP was developed. CETP was purified from human plasma to apparent homogeneity and used for raising anti-CETP antibodies in rabbits. The specificity of the polyclonal antiserum obtained was demonstrated by inhibition assays and immunoblot analysis. Before use in the CETP-IRMA, the antibodies were affinity-purified by chromatography on CETP-Sepharose. Sensitivity of the CETP-IRMA was 0.1 ng, and intra- and interassay coefficients of variation were 2.9 and 8.0%, respectively. In 30 normolipidemic healthy subjects, the mean (+/- SD) CETP concentration was 1.1 (+/- 0.22) micrograms/ml of plasma; individual values ranged from 0.644 to 1.694 micrograms CETP/ml and agreed well with measurements of CETP activity of the same samples (r = 0.85).

Patients with Type 1 (insulin-dependent) and Type 2 (non-insulin-dependent) diabetes mellitus are at increased risk of developing atherosclerotic vascular diseases. A variety of lipoprotein abnormalities have been described as being associated with this increased risk. In this study, apo(a) isoform frequencies and lipoprotein(a) [Lp(a)] concentrations were determined in Type 1 and Type 2 diabetic patients in order to investigate a possible contribution of Lp(a) to the increased risk for atherosclerosis in diabetes. No significant differences in plasma Lp(a) concentrations were found in two ethnically different populations (Austrians from the province of Tyrol and Hungarians from Budapest) in either type of diabetes when compared to respective control groups (91 Type 1 and 112 Type 2 diabetic patients vs 202 control subjects in the Hungarian study and 44 Type 1 diabetic and 44 Type 2 diabetic vs 125 control subjects in the Austrian study). There were also no significant apo(a) isoform frequency differences between both patient groups and control subjects in the two study groups. These data, obtained from two large ethnically different populations, provide no evidence of a contribution of Lp(a) to the increased risk for atherosclerosis in diabetes.

Rationale: The neuropeptide catestatin is an endogenous nicotinic cholinergic antagonist that acts as a pleiotropic hormone. Objective: Catestatin shares several functions with angiogenic factors. We therefore reasoned that catestatin induces growth of new blood vessels. Methods and Results: Catestatin induced migration, proliferation, and antiapoptosis in endothelial cells and exerted capillary tube formation in vitro in a Matrigel assay, and such effects were mediated via G protein, mitogen-activated protein kinase, and Akt. Catestatin-induced endothelial cell functions are further mediated by basic fibroblast growth factor, as shown by blockade of effects by a neutralizing fibroblast growth factor antibody. Furthermore, catestatin released basic fibroblast growth factor from endothelial cells and stimulated fibroblast growth factor signaling. In addition to its function on endothelial cells, catestatin also exerted effects on endothelial progenitor cells and vascular smooth muscle cells. In vivo, catestatin induced angiogenesis in the mouse cornea neovascularization assay and increased blood perfusion and number of capillaries in the hindlimb ischemia model. In addition to angiogenesis, catestatin increased density of arterioles/arteries and incorporation of endothelial progenitor cells in the hindlimb ischemia model, indicating induction of arteriogenesis and postnatal vasculogenesis. Conclusion: We conclude that catestatin acts as a novel angiogenic cytokine via a basic fibroblast growth factor–dependent mechanism.

Nitric oxide (NO) plays a critical role in the regulation of renal hemodynamics and tubular function after post-ischemic damage or sepsis. Diminished NO bioavailability contributes to endothelial dysfunction and may be caused by reduced NO synthesis due to substrate or co-factor deficiency. The aim of this study was to investigate the effects of NOS inhibition and NO depletion in a renal endo-epithelial bilayer model compared to monolayers of proximal tubular epithelial (HK-2) cells and endothelial cells of venous origin (EA.hy 926) with respect to cellular integrity, apoptosis and cytokine release. Two different NOS inhibitors have been used: an arginine-based-inhibitor, L-N(G)monomethyl-arginine (L-NMMA) and a cofactor-based-inhibitor, H4-amino-biopterin (4-ABH(4)) showing iNOS selectivity. We found significantly higher basal NO production by epithelial than by endothelial monolayers, which was significantly reduced by both NOS-inhibitors with a stronger effect demonstrated by 4-ABH(4). Furthermore we detected significant basal iNOS protein expression in unstimulated HK-2 cells. NOS inhibition by 4-ABH(4) was associated with increased LDH release, apoptosis and reduced IL-6 production in epithelial but not in endothelial monolayers. These effects on epithelial cells were abolished under co-culture conditions. In contrast, endothelial cells showed higher IL-6 and IL-8 release under co-culture conditions than in monolayers, with IL-8 production being largely suppressed by L-NMMA but not by 4-ABH(4). In conclusion, inhibition of basal NO production in epithelial monolayers shows detrimental effects on cell integrity and viability. Under co-culture conditions interrelation between epithelial and endothelial cells appears to counteract these potentially harmful effects of epithelial NOS inhibition.

BACKGROUND: Liver-selective thyromimetics have been reported to efficiently reduce plasma cholesterol through the hepatic induction of both, the low-density lipoprotein receptor (LDLr) and the high-density lipoprotein (HDL) receptor; the scavenger receptor class B type I (SR-BI). Here, we investigated the effect of the thyromimetic T-0681 on reverse cholesterol transport (RCT) and atherosclerosis, and studied the underlying mechanisms using different mouse models, including mice lacking LDLr, SR-BI, and apoE, as well as CETP transgenic mice. METHODOLOGY/PRINCIPAL FINDINGS: T-0681 treatment promoted bile acid production and biliary sterol secretion consistently in the majority of the studied mouse models, which was associated with a marked reduction of plasma cholesterol. Using an assay of macrophage RCT in mice, we found T-0681 to significantly increase fecal excretion of macrophage-derived neutral and acidic sterols. No positive effect on RCT was found in CETP transgenic mice, most likely due to the observed decrease in plasma CETP mass. Studies in SR-BI KO and LDLr KO mice suggested hepatic LDLr to be necessary for the action of T-0681 on lipid metabolism, as the compound did not have any influence on plasma cholesterol levels in mice lacking this receptor. Finally, prolonged treatment with T-0681 reduced the development of atherosclerosis by 60% in apoE KOs on Western type diet. In contrast, at an earlier time-point T-0681 slightly increased small fatty streak lesions, in part due to an impaired macrophage cholesterol efflux capacity, when compared to controls. CONCLUSIONS/SIGNIFICANCE: The present results show that liver-selective thyromimetics can promote RCT and that such compounds may protect from atherosclerosis partly through induction of bile acid metabolism and biliary sterol secretion. On-going clinical trials will show whether selective thyromimetics do prevent atherosclerosis also in humans.

The status of fasting triglycerides as a risk factor for coronary artery disease (CAD) has been considered weak because in multivariate analyses, triglycerides tend to be eliminated by high density lipoprotein (HDL) cholesterol. To further evaluate the role of triglycerides in CAD, we employed postprandial lipemia as a more informative means of characterizing triglyceride metabolism. In 61 male subjects with severe CAD and 40 control subjects without CAD as verified by angiography, we measured cholesterol; triglycerides; HDL cholesterol; HDL2 cholesterol; and apolipoproteins A-I, A-II, and B in fasting plasma and triglycerides before and 2, 4, 6, and 8 hours after a standardized test meal. Both the maximal triglyceride increase and the magnitude of postprandial lipemia (area under the triglyceride curve over 8 hours after the meal) were higher in cases than in control subjects. Single postprandial triglyceride levels 6 and 8 hours after the meal were highly discriminatory (p < 0.001), and by logistic-regression analysis displayed an accuracy of 68% in predicting the presence or absence of CAD. In this respect, accuracy was higher than that of HDL2 cholesterol (64%) and equal to that of apolipoprotein B (68%), the most discriminatory fasting parameter. Multivariate logistic-regression analysis was performed to reduce the number of risk factors to those that were statistically independent. This statistical procedure selected postprandial but not fasting triglycerides into the most accurate multivariate model, which also contained the accepted risk factors HDL2 cholesterol, apolipoprotein B, and age. This model classified 82% of subjects correctly. We conclude that triglycerides are independent predictors of CAD in multivariate analyses including HDL cholesterol, provided that a challenge test of triglyceride metabolism such as postprandial lipemia is used. The study suggests that the metabolism of triglycerides is a critical determinant of cholesterol metabolic routing. The findings support the concept that the negative association between HDL cholesterol levels and CAD actually originates in part from a positive relation between CAD and plasma triglycerides, as ascertained in the postprandial state.

Overt hypothyroidism most often causes moderately elevated cholesterol and triglycerides; but, in genetically predisposed individuals, it can also trigger frank hyperlipidemia, e.g. type III hyperlipoproteinemia. In contrast, in subclinical hypothyroidism, T4 lowers low-density lipoprotein cholesterol (LDL-C) by only 3.5–6.0 mg/dl LDL-C for each 1 mU/l thyroid-stimulating hormone (TSH) increase from baseline, a finding barely perceptible in individual patients. In humans, T3 decreases apoB-containing IDL, LDL and chylomicron remnant particles by up-regulation of LDL receptors and despite a concomitant increase in HMGCoA reductase in the liver. In rodents, T3 also up-regulates CYP7A1, ABCG5 and ABCG8 which interact to increase bile acid synthesis and biliary elimination of cholesterol. Thyromimetics, selective for either thyroid hormone-receptor β or liver, lower both LDL-C in humans and HDL-C in mice, thereby promoting reverse cholesterol transport. Interestingly, the thyromimetic T-0681 protects cholesterol-fed rabbits from atherosclerosis. If safety concerns with TRβ-selective thyromimetics can be addressed (i.e. the observed pituitary feed-back inhibition leading to low TSH levels), this class of drugs may complement statins in tackling the burden of atherosclerosis in humans.

The relationship between plasma levels of Lp[a] and LDL was examined using dietary regimens. In 81 normolipidemic male outpatients, dietary cholesterol was increased by consuming six eggs per day from a mean (SD) level of 311 (162) to 1430 (198) mg per day. Mean (SD) LDL-cholesterol levels increased from 102 (26) mg/dl to 120 (33) mg/dl (P less than 0.001), while mean (SD) Lp[a] levels were 5.5 (6.1) mg/dl on the basal diet and 5.6 (6.4) mg/dl on the cholesterol-rich diet. No significant correlation was observed between increases in either LDL-cholesterol or apolipoprotein B to Lp[a], nor was there any relationship between individual baseline levels of Lp[a] and dietary-induced changes of Lp[a]. Fourteen of the 81 participants were reexamined under strict nutritional control. Four diets with 40% of calories as fat, but differing in the type of fat and the amount of cholesterol, were administered sequentially to all subjects. As expected, mean (SD) LDL-cholesterol and apolipoprotein B levels were highest on the saturated fat, high cholesterol diet (112 (32) mg/dl and 79 (22) mg/dl) and lowest on the polyunsaturated fat, low cholesterol diet (77 (27) mg/dl and 53 (18) mg/dl). In contrast, mean Lp[a] levels did not significantly change among the four diets (range 4.2-4.9 mg/dl). No correlation of Lp[a] responses with changes in plasma lipids, apolipoproteins, or lipoproteins was observed on any diet. These data suggest that determinants of plasma Lp[a] levels are distinctly different from the determinants of plasma LDL levels in normolipidemic males.

Objective: Adipocyte fatty acid-binding protein (A-FABP) is a plasma biomarker recently associated with the metabolic syndrome. The aim of these studies was to investigate changes of A-FABP during profound weight loss induced by laparoscopic adjustable gastric banding (LAGB). Methods and Procedures: In study one, 29 severely obese female subjects were examined before and 1 year after surgical treatment. A subgroup of 10 patients was investigated in 3-month intervals. Metabolic parameters were determined using standard methods, and A-FABP was detected using a commercially available enzyme-linked immunosorbent assay. Results: Mean weight loss after 1 year was 24.9 kg (P < 0.001), mainly due to a decrease in fat mass. Metabolic parameters improved substantially. However, serum A-FABP remained stable. In study two, a subgroup of 10 patients was examined quarterly to determine the time course of A-FABP changes. Quarterly measurements of serum A-FABP were significantly higher than baseline levels with the highest A-FABP value after the first 3 months, where patients had highest weight loss. Discussion: Our results in study one show that A-FABP serum levels are positively associated with body weight and fat mass. However, 1 year after pronounced weight loss A-FABP levels remained unchanged. In study two, time course analyses revealed maximum increase of serum A-FABP in parallel to highest weight loss, which allows to suppose that A-FABP is not only a biomarker of the metabolic syndrome in the steady state, but also a marker of weight changes in dynamic situations.

We studied the effects of different blood collection and processing procedures on quantification of apolipoprotein (apo) B by radioimmunoassay. High-density lipoprotein subfractions HDL3 and HDL2 and isolated apoA-I did not cross-react in the assay. Analytical recovery of apoB at different doses of very-low- and low-density lipoproteins were complete. Inter- and intra-assay coefficients of variation (CVs) averaged 7.4% and 6.0%, respectively. Blood from 20 subjects was collected into tubes containing EDTA alone or EDTA with antiproteolytic and antioxidant agents; one half of each plasma was separated immediately, half after 3 h at 4 degrees C. Regardless of the addition of protective agents or the time difference in separating plasma from other blood elements, freezing plasma at -70 degrees C decreased apoB content a similar amount, an average of 6.8%. This loss of apoB immunoreactivity was not related to apoB content in fresh plasma. Analysis of variance showed no differential effect on apoB content by the various additions to whole blood or plasma. No additional apoB content was lost in once-frozen aliquots of three human plasma pools during storage at -70 degrees C for up to 18 months. We conclude that concentrations of apoB in human plasma can be measured reliably after long-term storage, although the absolute value may decrease slightly as a result of freezing.

Objectives Microsomal triglyceride transfer protein (MTP) transfers lipids into apoprotein B-containing lipoproteins for secretion from liver, intestine, and heart. We hypothesized the −493T single nucleotide polymorphism in the MTP promoter region to be associated with altered lipoprotein levels and with presence of peripheral arterial disease (PAD). Design and methods 433 patients with symptomatic PAD and 433 controls matched for sex and age from the Linz Peripheral Arterial Disease (LIPAD) study were genotyped cross-sectionally for the −493T single nucleotide polymorphism in the promoter region of the MTP gene. Results The frequency of the −493T allele in patients with PAD was 0.320, whereas it was 0.255 in controls (p

Variants in the adenosine triphosphate–binding-cassette transporter 1 (ABCA1) gene are known to affect high-density lipoprotein cholesterol and plasma triglycerides and the development of atherosclerosis. We investigated the influence of the R219K and I883M variants in the ABCA1 gene on plasma lipids and carotid intima media thickness and plaque extent in 688 healthy men (40-60 years old). The R219K variant showed no effect on plasma lipids, but carriers of the K allele displayed a lower intima media thickness (P = .001) and a reduced risk of advanced plaque extent (odds ratio [OR], 0.59; 0.39-0.88; P = .009) compared with noncarriers. However, this risk reduction was observed in nonsmokers only (OR, 0.47; 0.27-0.80; P < .001), but not in smokers (OR, 0.75; 0.41-1.39; P = .2). The I883M variant showed no effect on plasma lipids or carotid atherosclerosis. Risk of advanced plaque extent was reduced in subjects carrying the R219K variant alone (OR, 0.59; 0.38-0.94; P = .025), but not in subjects carrying both variants. Haplotype distribution did not differ between subjects with and without advanced atherosclerosis irrespective of smoking history. We conclude that smoking abrogates the protective effect of the R219K.

Expression of angiogenic cytokines like vascular endothelial growth factor is enhanced by hypoxia. We tested the hypothesis that decreased oxygen levels up-regulate the angiogenic factor secretoneurin. In vivo, muscle cells of mouse ischemic hind limbs showed increased secretoneurin expression, and inhibition of secretoneurin by a neutralizing antibody impaired the angiogenic response in this ischemia model. In a mouse soft tissue model of hypoxia, secretoneurin was increased in subcutaneous muscle fibers. In vitro, secretoneurin mRNA and protein were up-regulated in L6 myoblast cells after exposure to low oxygen levels. The hypoxia-dependent regulation of secretoneurin was tissue specific and was not observed in endothelial cells, vascular smooth muscle cells, or AtT20 pituitary tumor cells. The hypoxia-dependent induction of secretoneurin in L6 myoblasts is regulated by hypoxia-inducible factor-1alpha, since inhibition of this factor using si-RNA inhibited up-regulation of secretoneurin. Induction of secretoneurin by hypoxia was dependent on basic fibroblast growth factor in vivo and in vitro, and inhibition of this regulation by heparinase suggests an involvement of low-affinity basic fibroblast growth factor binding sites. In summary, our data show that the angiogenic cytokine secretoneurin is up-regulated by hypoxia in muscle cells by hypoxia-inducible factor-1alpha- and basic fibroblast growth factor-dependent mechanisms.