A New Structural Model of Apolipoprotein B100 Based on Computational Modeling and Cross Linking.

ApoB-100 is a member of a large lipid transfer protein superfamily and is one of the main apolipoproteins found on low-density lipoprotein (LDL) and very low-density lipoprotein (VLDL) particles. Despite its clinical significance for the development of cardiovascular disease, there is limited information on apoB-100 structure. We have developed a novel method based on the "divide and conquer" algorithm, using PSIPRED software, by dividing apoB-100 into five subunits and 11 domains. Models of each domain were prepared using I-TASSER, DEMO, RoseTTAFold, Phyre2, and MODELLER. Subsequently, we used disuccinimidyl sulfoxide (DSSO), a new mass spectrometry cleavable cross-linker, and the known position of disulfide bonds to experimentally validate each model. We obtained 65 unique DSSO cross-links, of which 87.5% were within a 26 Å threshold in the final model. We also evaluated the positions of cysteine residues involved in the eight known disulfide bonds in apoB-100, and each pair was measured within the expected 5.6 Å constraint. Finally, multiple domains were combined by applying constraints based on detected long-range DSSO cross-links to generate five subunits, which were subsequently merged to achieve an uninterrupted architecture for apoB-100 around a lipoprotein particle. Moreover, the dynamics of apoB-100 during particle size transitions was examined by comparing VLDL and LDL computational models and using experimental cross-linking data. In addition, the proposed model of receptor ligand binding of apoB-100 provides new insights into some of its functions.

Inhibition Mechanism of Some Vinylalkylimidazolium-Based Polymeric Ionic Liquids against Acid Corrosion of API 5L X60 Steel: Electrochemical and Surface Studies.

A corrosion inhibition mechanism of API 5L X60 steel exposed to 1.0 M H2SO4 was proposed from the evaluation of three vinylalkylimidazolium poly(ionic liquids) (PILs), employing electrochemical and surface analysis techniques. The synthesized PILs were classified as mixed-type inhibitors whose surface adsorption was promoted mainly by bromide and imidazolate ions, which along with vinylimidazolium cations exerted a resistive effect driven by a charge transfer process by means of a protective PIL film with maximal efficiency of 85% at 175 ppm; the steel surface displayed less surface damage due to the formation of metal-PIL complex compounds.

Lipoprotein Assessment in the twenty-first Century.

Based on decades of both basic science and epidemiologic research, there is overwhelming evidence for the causal relationship between high levels of cholesterol, especially low-density lipoprotein cholesterol and cardiovascular disease. Risk evaluation and monitoring the response to lipid-lowering therapies are heavily dependent on the accurate assessment of plasma lipoproteins in the clinical laboratory. This article provides an update of lipoprotein metabolism as it relates to atherosclerosis and how diagnostic measures of lipids and lipoproteins can serve as markers of cardiovascular risk, with a focus on recent advances in cardiovascular risk marker testing.

Synthesis of water-soluble ionic terpolymers by inverse microemulsion and solution polymerization methods.

The synthesis of terpolymers can lead to very interesting combinations of monomers, which can affect the solubility of the polymer, its thermal stability or resistance in saline aqueous media. Free-radical inverse microemulsion and solution polymerization techniques were used to prepare water-soluble acrylamide-N-vinylpyrrolidone-(vinylbenzyl)trimethylammonium chloride terpolymers. The formulation of the polymerizable microemulsion was optimized by using the screening of surfactant percentage and HLB concept. The influence of synthesis temperature on the terpolymer composition and molecular weight was investigated. The reactions were carried out at 60, 70, and 75 °C for the microemulsion technique and at 40, 50, and 55 °C for the solution polymerization technique. The reaction products from both processes were water-soluble polymers, and the two techniques reached high conversions and molecular masses. Maximal molecular weights were displayed by terpolymers prepared by the solution method at 40 °C (959, 840 g mol-1) and the inverse microemulsion method at 60 °C (795, 994 g mol-1). According to NMR analysis, the highest amount of (vinylbenzyl) trimethylammonium chloride was incorporated into the terpolymer structure by the inverse microemulsion method. In contrast, the solution method yielded higher contents of acrylamide and N-vinylpyrrolidone. The viscosity properties of the terpolymers in aqueous solutions were directly correlated to their molecular weight and synthesis conditions.

Transgelin: a new gene involved in LDL endocytosis identified by a genome-wide CRISPR-Cas9 screen.

A significant proportion of patients with elevated LDL and a clinical presentation of familial hypercholesterolemia do not carry known genetic mutations associated with hypercholesterolemia, such as defects in the LDL receptor. To identify new genes involved in the cellular uptake of LDL, we developed a novel whole-genome clustered regularly interspaced short palindromic repeat-Cas9 KO screen in HepG2 cells. We identified transgelin (TAGLN), an actin-binding protein, as a potentially new gene involved in LDL endocytosis. In silico validation demonstrated that genetically predicted differences in expression of TAGLN in human populations were significantly associated with elevated plasma lipids (triglycerides, total cholesterol, and LDL-C) in the Global Lipids Genetics Consortium and lipid-related phenotypes in the UK Biobank. In biochemical studies, TAGLN-KO HepG2 cells showed a reduction in cellular LDL uptake, as measured by flow cytometry. In confocal microscopy imaging, TAGLN-KO cells had disrupted actin filaments as well as an accumulation of LDL receptor on their surface because of decreased receptor internalization. Furthermore, TAGLN-KO cells exhibited a reduction in total and free cholesterol content, activation of SREBP2, and a compensatory increase in cholesterol biosynthesis. TAGLN deficiency also disrupted the uptake of VLDL and transferrin, other known cargoes for receptors that depend upon clathrin-mediated endocytosis. Our data suggest that TAGLN is a novel factor involved in the actin-dependent phase of clathrin-mediated endocytosis of LDL. The identification of novel genes involved in the endocytic uptake of LDL may improve the diagnosis of hypercholesterolemia and provide future therapeutic targets for the prevention of cardiovascular disease.

Bayesian network analysis of panomic biological big data identifies the importance of triglyceride-rich LDL in atherosclerosis development.

Introduction: We sought to explore biomarkers of coronary atherosclerosis in an unbiased fashion. Methods: We analyzed 665 patients (mean ± SD age, 56 ± 11 years; 47% male) from the GLOBAL clinical study (NCT01738828). Cases were defined by the presence of any discernable atherosclerotic plaque based on comprehensive cardiac computed tomography (CT). De novo Bayesian networks built out of 37,000 molecular measurements and 99 conventional biomarkers per patient examined the potential causality of specific biomarkers. Results: Most highly ranked biomarkers by gradient boosting were interleukin-6, symmetric dimethylarginine, LDL-triglycerides [LDL-TG], apolipoprotein B48, palmitoleic acid, small dense LDL, alkaline phosphatase, and asymmetric dimethylarginine. In Bayesian analysis, LDL-TG was directly linked to atherosclerosis in over 95% of the ensembles. Genetic variants in the genomic region encoding hepatic lipase (LIPC) were associated with LIPC gene expression, LDL-TG levels and with atherosclerosis. Discussion: Triglyceride-rich LDL particles, which can now be routinely measured with a direct homogenous assay, may play an important role in atherosclerosis development. Clinical trial registration: GLOBAL clinical study (Genetic Loci and the Burden of Atherosclerotic Lesions); [https://clinicaltrials.gov/ct2/show/NCT01738828?term=NCT01738828&rank=1], identifier [NCT01738828].

A New Equation Based on the Standard Lipid Panel for Calculating Small Dense Low-Density Lipoprotein-Cholesterol and Its Use as a Risk-Enhancer Test.

BACKGROUND: Increased small dense low-density lipoprotein-cholesterol (sdLDL-C) is a risk factor for atherosclerotic cardiovascular disease (ASCVD) but typically requires advanced lipid testing. We describe two new equations, first one for calculating large buoyant LDL-C (lbLDL-C), based only upon results from the standard lipid panel, and the second one for sdLDL-C. METHODS: Equations for sdLDL-C and lbLDL-C were generated with least-squares regression analysis using the direct Denka sdLDL-C assay as reference (n = 20 171). sdLDL-C was assessed as a risk-enhancer test in the National Heart and Nutrition Examination Survey (NHANES), and for its association with ASCVD in the Multi-Ethnic Study of Atherosclerosis (MESA). RESULTS: The newly derived equations depend on two terms, namely LDL-C as determined by the Sampson equation, and an interaction term between LDL-C and the natural log of triglycerides (TG). The lbLDL-C equation (lbLDLC=1.43 × LDLC-0.14 ×(ln⁡(TG)× LDLC)- 8.99) was more accurate (R2 = 0.933, slope = 0.94) than the sdLDL-C equation (sdLDLC=LDLC- lbLDLC; R2 = 0.745, slope = 0.73). Using the 80th percentile (46 mg/dL) as a cut-point, sdLDL-C identified in NHANES additional high-risk patients not identified by other risk-enhancer tests based on TG, LDL-C, apolipoprotein B, and nonHDL-C. By univariate survival-curve analysis, estimated sdLDL-C was superior to other risk-enhancer tests in predicting ASCVD events in MESA. After multivariate adjustment for other known ASCVD risk factors, estimated sdLDL-C had the strongest association with ASCVD compared to other lipid parameters, including measured sdLDL-C. CONCLUSIONS: Estimated sdLDL-C could potentially be calculated on all patients tested with a standard lipid panel to improve ASCVD risk stratification.

UNILATERAL SINGLE VAGINAL ECTOPIC URETER WITH IPSILATERAL HYPOPLASTIC AND DEGENERATED KIDNEY ASSOCIATED WITH INFERTILITY IN IBERIAN IBEX (CAPRA PYRENAICA) DOES.

This article describes the urinogenital condition of three female Iberian ibexes (Capra pyrenaica-one infertile 3-yr-old adult and two prepubertal animals aged 1 (PP1) and 2 (PP2) yr, respectively, all raised in captivity. All showed constant urinal dribbling, leading to ulcerative dermatitis in the vulvar area. Housed in a stable with other females, the adult did not become pregnant after male contact in either of two consecutive mating seasons. Vaginoscopy and laparoscopic exploration performed on the prepubertal females revealed abnormalities of the vagina and urinary bladder. Ultrasound examination revealed atrophy of the left kidney in the adult female and PP1, and of the right kidney in PP2, with degeneration of the renal pelvis. A paraovarian cyst with hydrosalpinx was also detected in the left oviduct of the adult female. Postmortem analysis of the adult and PP2, which shared a mother, confirmed an extramural single ectopic ureter with vaginal insertion associated with atrophy of the ipsilateral kidney. Though PP1 was officially unrelated to the latter animals, all three might have had a common ancestor in their lineages.

Interleukin 10 promotes macrophage uptake of HDL and LDL by stimulating fluid-phase endocytosis.

OBJECTIVE: Highly elevated plasma levels of interleukin-10 (IL-10) are causally associated with "Disappearing HDL Syndrome" and low plasma LDL-cholesterol, but the underlying mechanism is poorly understood. Fluid-phase endocytosis, a process highly dependent on actin dynamics, enables cells to internalize relatively high amounts of extracellular fluids and solutes. We sought to investigate whether IL-10 induces lipoprotein uptake by fluid-phase endocytosis in macrophages. METHODS AND RESULTS: Macrophages (RAW264.7, Kupffer and human) were incubated with vehicle (PBS) or IL-10 (20 ng/ml) for 7 days. Uptake of HDL, LDL, and/or fluid-phase endocytosis probes (albumin-Alexa680®, 70 kDa FITC-Dextran and Lucifer Yellow, LY) was evaluated by FACS. Intracellular cofilin and phosphorylated cofilin (p-cofilin) levels were determined by immunoblotting. Macrophage uptake of lipoproteins and probes was non-saturable and increased after IL-10 incubation (p < 0.0001). Furthermore, pre-incubation with fluid-phase endocytosis inhibitors (LY294002, Latrunculin A, and Amiloride) significantly reduced uptake (p < 0.05). IL-10 increased the cofilin/p-cofilin ratio (p = 0.021), signifying increased cofilin activation and hence filamentous actin. Consistently, phalloidin staining revealed increased filamentous actin in macrophages after IL-10 treatment (p = 0.0018). Finally, RNA-seq analysis demonstrated enrichment of gene sets related to actin filament dynamics, membrane ruffle formation and endocytosis in IL-10-treated macrophages (p < 0.05). IL-10 did not alter mRNA levels of Ldlr, Vldlr, Scarb1, Cd36 or Lrp1. In primary human monocyte-derived macrophages and murine Kupffer cells, IL-10 incubation also increased uptake of lipoproteins, albumin and LY (p < 0.01). CONCLUSIONS: Interleukin-10 induces the uptake of HDL and LDL by fluid-phase endocytosis by increasing actin-filament rearrangement in macrophages, thus providing a plausible mechanism contributing to "Disappearing HDL Syndrome".

Fetal and postnatal zinc restriction: Sex differences in metabolic alterations in adult rats.

OBJECTIVE: Intrauterine and postnatal micronutrient malnutrition may program metabolic diseases in adulthood. We examined whether moderate zinc restriction in male and female rats throughout fetal life, lactation, or postweaning growth induces alterations in liver, adipose tissue, and intermediate metabolism. METHODS: Female Wistar rats were fed low-zinc or control zinc diets from pregnancy to offspring weaning. After weaning, male and female offspring were fed either a low-zinc or a control zinc diet. At 74 d of life, oral glucose tolerance tests were performed and serum metabolic profiles were evaluated. Systolic blood pressure and oxidative stress and morphology of liver and retroperitoneal adipose tissue were evaluated in 81 d old offspring. RESULTS: Zinc restriction during prenatal and postnatal life induced an increase in systolic blood pressure, hyperglycemia, hypertriglyceridemia, higher serum glucose levels at 180 min after glucose overload, and greater insulin resistance indexes in male rats. Hepatic histologic studies revealed no morphologic alterations, but an increase in lipid peroxidation and catalase activity were identified in zinc-deficient male rats. Adipose tissue from zinc-deficient male rats had adipocyte hypertrophy, an increase in lipid peroxidation, and a reduction in catalase and glutathione peroxidase activity. Adequate dietary zinc content during postweaning growth reversed basal hyperglycemia, hypertriglyceridemia, insulin resistance indexes, hepatic oxidative stress, and adipocyte hypertrophy. Female rats were less sensitive to the metabolic effects of zinc restriction. CONCLUSIONS: This study strengthens the importance of a balanced intake of zinc during growth to ensure adequate lipid and carbohydrate metabolism in adult life.

Nonalcoholic fatty liver disease associated with metabolic syndrome: Influence of liver fibrosis stages on characteristics of very low-density lipoproteins.

BACKGROUND: We evaluated possible changes in VLDLcharacteristics, and metabolic related factors, in MetS-associated NAFLD and accompanying liver fibrosis. METHODS: We studied 36 MetS patients with biopsy-proven NAFLD (MetS+NAFLD) and 24 MetS without ultrasound NAFLD evidence. Further, MetS+NAFLD was sub-divided according to fibrosis stage into, non-to-moderate (F0-F2, n=27) and severe (F3-F4, n=9) fibrosis. We measured: lipid profile, VLDL composition and size (size exclusion-HPLC), CETP and lipoprotein lipase (LPL) activities and adiponectin. Additionally, in MetS+NAFLD type IV collagen 7S domain was measured. RESULTS: MetS+NAFLD showed increased VLDL-mass, VLDL particle number, VLDL-triglyceride% and large VLDL-% (p<0.04). CETP activity tended to increase in MetS+NAFLD (p=0.058), while LPL activity was unchanged. Moreover, in MetS+NAFLD, adiponectin was decreased (p<0.001), and negatively correlated with VLDL-mass and VLDL particle number (p<0.05), independently of insulin-resistance. Within MetS+NAFLD group, despite greater insulin-resistance, patients with severe fibrosis showed lower plasma triglycerides, VLDL-mass, VLDL-triglyceride%, large VLDL-% and CETP activity (p<0.05), while type IV collagen was increased (p=0.009) and inversely correlated with large VLDL-% (p=0.045). CONCLUSIONS: In MetS, NAFLD is associated with larger and triglyceride over-enriched circulating VLDLs, of greater atherogenicity. However, when NAFLD progresses to severe fibrosis, circulating VLDL features apparently improved, probably due to early alterations in hepatic synthetic function.

New evidence for the therapeutic potential of curcumin to treat nonalcoholic fatty liver disease in humans.

INTRODUCTION: The immune system acts on different metabolic tissues that are implicated in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). Leptin and linoleic acid have the ability to potentially affect immune cells, whereas curcumin is a known natural polyphenol with antioxidant and anti-inflammatory properties. AIMS: This study was designed to evaluate the pro-inflammatory and pro-oxidant effects of leptin and linoleic acid on immune cells from patients with NAFLD and to corroborate the modulatory effects of curcumin and its preventive properties against the progression of NAFLD using a high-fat diet (HFD)-induced NAFLD/nonalcoholic steatohepatitis mouse model. RESULTS: The ex vivo experiments showed that linoleic acid increased the production of reactive oxygen species in monocytes and liver macrophages, whereas leptin enhanced tumor necrosis factor-α (TNF-α) production in monocytes and interferon-γ production in circulating CD4+ cells. Conversely, oral administration of curcumin prevented HFD-induced liver injury, metabolic alterations, intrahepatic CD4+ cell accumulation and the linoleic acid- and leptin- induced pro-inflammatory and pro-oxidant effects on mouse liver macrophages. CONCLUSION: Our findings provide new evidence for the therapeutic potential of curcumin to treat human NAFLD. However, the development of a preventive treatment targeting human circulating monocytes and liver macrophages as well as peripheral and hepatic CD4+ cells requires additional research.

Efectos inflamatorios, oxidativos y aterogénicos del receptor endotelial de la lipoproteína de baja densidad oxidada-1 / Inflammatory, oxidative and atherogenic effects of endothelial lectin-like receptor of oxidized low density lipoprotein-1 / Efeitos inflamatórios, oxidativos e aterogênicos do receptor endotelial da lipoproteína de baixa densidade oxidativa-1

LOX-1 es un receptor endotelial de la familia de las lectinas. Su actividad biológica tiene un fuerte impacto en los fenómenos inflamatorios, oxidativos y aterogénicos endoteliales. Cuando se conoció el receptor de la lipoproteína de baja densidad (RLDL) y su regulación, se afirmó el papel aterogénico del colesterol transportado en esta lipoproteína (C-LDL). Este papel de las lipoproteínas fue la base de la denominación de dislipoproteinemias en reemplazo de dislipemias. En condiciones post-prandiales, las lipoproteínas ricas en triglicéridos, como quilomicrones y lipoproteínas de muy baja densidad (VLDL), son degradadas por la lipoproteína lipasa (LPL) de la pared vascular, produciéndose remanentes de quilomicrones (RQ) y lipoproteínas de densidad intermedia (IDL), respectivamente, que en conjunto se denominan lipoproteínas remanentes (RLPs). Dependiendo del estrés oxidativo las RLPs son oxidables y pueden unirse al LOX-1. También se liberan ácidos grasos que injurian células endoteliales y contribuyen a abrir brechas en el endotelio, que en condiciones fisiológicas es una barrera de células con uniones estrechas. El dominio intracelular de LOX-1 regula el reconocimiento de lipoproteínas de baja densidad oxidadas (LDLOX) y de RLPs. Además, posee un efecto dependiente de los radicales reactivos de oxígeno (ROS). Su dominio transmembrana actúa en el pasaje de LDLOX y monocitos al subendotelio. La inhibición de LOX-1 con anticuerpos específicos impide su unión con LDLOX, restableciendo la barrera entre el lumen vascular y el subendotelio. En cambio, las LDLOX unidas al dominio transmembrana, producen apoptosis de las células endoteliales y suprimen uniones estrechas intercelulares en el endotelio, facilitando la actividad de las moléculas de adhesión leucocitarias que promueven el pasaje al subendotelio de los elementos del lumen, tales como monocitos, plaquetas, LDLOX, RLPs oxidables y lipoproteínas (a) (Lp(a)) semejantes al plasminógeno. Las LDLOX subendoteliales aumentan la movilidad de células musculares lisas. Los monocitos subendoteliales se establecen como residentes, e incorporan LDLOX, convirtiéndose sucesivamente en macrófagos, células espumosas y lesiones aterogénicas. Sin embargo, desde Assmann G y su estudio PROCAM no puede ignorarse el papel de los triglicéridos y colesterol de lipoproteínas de alta densidad (C-HDL) como componentes del cuadro de riesgo en ECV.

LOX-1 is an endothelial receptor belonging to the family of lectins. Its biological activity has a strong impact on inflammatory, oxidative and atherogenic phenomena in endothelium. When Low Density Lipoprotein receptor (RLDL) and its regulation were known, the atherogenic role of the cholesterol transported in LDL (LDL-C) was confirmed. This lipoprotein role in atherosclerosis was the base to use the term dyslipoproteinemia instead of dyslipidemia. In post-prandial conditions, triglyceride-rich lipoproteins like chylomicrons and very low-density lipoproteins (VLDL), are degraded by lipoprotein lipase (LPL) on the vascular wall, with the resultant formation of chylomicron remnants (CR) and intermediate density lipoproteins (IDL) respectively, which as a whole are called remnant lipoproteins (RLPs). Depending on oxidative stress, RLPs are oxidized and then they can bind the LOX-1. In this process, fatty acids are also released, injuring endothelial cells and contributing to open gaps in endothelium, which under physiological conditions, is a barrier of cells with tight junctions. The intracellular domain of LOX-1 regulates the recognition of oxidized LDL (oxLDL) and RLPs, and its effect depends on reactive oxygen species (ROS). LOX-1 transmembrane domain acts in the passage of oxLDL and monocytes to the sub-endothelium. Inhibition of LOX-1 by specific antibodies prevents its binding with OxLDL, restoring the barrier between the vascular lumen and sub-endothelium. By contrast, the oxLDL, attached to the transmembrane domain, produce apoptosis of endothelial cells and the suppression of narrow intercellular junctions in the endothelium. Thus, enabling the activity of leucocyte adhesion molecules that promote the transfer to subendothelial elements lumen of monocytes, platelets, oxLDL, oxidized RLPs and lipoprotein (a) (Lp (a)), similar to plasminogen such as. Sub-endothelial OxLDL increase the mobility of smooth muscle cells. Sub-endothelial monocytes establish as resident, up-take oxLDL and successively become into macrophages, foam cells and atherosclerotic lesions. However, since Assman’s PROCAM study, the role of triglycerides and High Density Lipoprotein-cholesterol (HDL-C), as components of cardiovascular risk, cannot be ignored.

LOX-1 é um receptor endotelial da família das lectinas. Sua atividade biológica tem um importante impacto nos fenômenos inflamatórios, oxidativos e aterogênicos endoteliais. Quando foi conhecido o receptor da lipoproteína de baixa densidade (RLDL) e sua regulação, afirmou-se o papel aterogênico do colesterol transportado nesta lipoproteína (C-LDL). Este papel das lipoproteínas foi a base da denominação de dislipoproteinemias em substituição de dislipidemias. Em condições pós-prandiais, as lipoproteínas ricas em triglicérides como quilomícrons e Lipoproteínas de muito baixa densidade (VLDL) são degradadas pela lipoproteína lipase (LPL) da parede vascular, produzindo remanescentes de quilomícrons (RQ) e lipoproteínas de densidade intermediária (IDL) respectivamente, que em conjunto são chamadas lipoproteínas remanescentes (RLPs). Dependendo do estresse oxidativo, as RLPs são oxidáveis e podem se ligar ao LOX-1. Também são liberados ácidos graxos que injuriam células endoteliais e contribuem na abertura de fendas no endotélio, que em condições fisiológicas é uma barreira de células com uniões estreitas. O domínio intracelular de LOX-1 regula o reconhecimento de lipoproteínas de baixa densidade oxidativa (LDLOX) e de RLPs. Também possui um efeito dependente dos radicais reativos de oxigênio (ROS). Seu domínio transmembrana atua na passagem de LDLOX e monócitos para o subendotélio. A inibição de LOX-1 com anticorpos específicos impede sua união com LDLOX restabelecendo a barreira entre o lúmem vascular e o subendotélio. Entretanto, as LDLOX ligadas ao domínio transmembrana produzem apoptose das células endoteliais e suprimem estreitas junções intercelulares no endotélio, facilitando a atividade das moléculas de adesão leucocitária que promovem a passagem para o subendotélio de elementos do lúmem, tais como monócitos, plaquetas, LDLOX, RLPs oxidáveis e lipoproteínas (a) [Lp(a)] semelhantes ao plasminogênio. As LDLOX subendoteliais aumentam a mobilidade das células musculares lisas. Os monócitos subendoteliais se estabelecem como residentes, e incorporam LDLOX, virando sucessivamente em macrófagos, células espumosas e lesões aterogênicas. No entanto, desde Assman G e seu estudo PROCAM, não pode se ignorar o papel dos triglicérides e do colesterol de lipoproteínas de alta densidade (C-HDL) como componentes do evento de risco em ECV.

Adiponectina determinaría el predominio de VLDL alteradas en el síndrome metabólico / Adiponectin would determine the predominance of altered VLDL in metabolic syndrome / Adiponectina iria determinar o predomínio de VLDL alteradas na síndrome metabólica

El objetivo del trabajo fue evaluar si la reducción de adiponectina (ADP) en el síndrome metabólico (SMet), influencia las características aterogénicas de VLDL. Se estudiaron 45 pacientes con SMet y 15 controles sanos. En suero en ayunas se midió perfil lipídico, ácidos grasos libres (AGL), ADP, se aisló VLDL (d<1,006 g/L) caracterizándola en su composición química y tamaño (HPLC-exclusión molecular). En plasma post-heparínico se determinó la actividad de lipoproteína lipasa (LPL). En SMet VLDL mostró incremento de masa, número de partículas, contenido en triglicéridos-VLDL y mayor proporción de VLDL grandes (p<0,05). El incremento de AGL correlacionó con la masa de VLDL (r=0,36; p=0,009), número de partículas-VLDL (r=0,45; p=0,0006) y %-VLDL grandes (r=0,32; p=0,02). SMet mostró descenso en ADP (7,4±4,8 vs. 15,5±7,2 μg/mL, p=0,01) y en actividad de LPL (p=0,01), que correlacionaron entre si (r=0,38; p=0,01; ajustado por HOMA-IR y cintura: β=0,35; p=0,02). ADP correlacionó negativamente con AGL y %-VLDL grandes (p<0,03). Se concluye que en SMet la disminución de ADP favorecería la secreción de VLDL sobre-enriquecidas en triglicéridos y de mayor tamaño, y además retardaría el catabolismo de VLDL mediado por LPL, resultando en la acumulación de VLDL alteradas en circulación con características aterogénicas.

The aim of the work was to evaluate whether the reduction of adiponectin (ADP) in metabolic syndrome (MetS) affects the atherogenic features of VLDL. A total of 45 patients with MetS (ATPIII) and 15 healthy controls were studied. In fasting serum, lipid profile, free fatty acids (FFA) and ADP were determined. VLDL was isolated (d<1.006 g/L) and characterized in chemical composition and size (size exclusion-HPLC). In post-heparin plasma, lipoprotein lipase (LPL) activity was measured. In MetS, VLDL showed increased total mass, particle number, VLDL-triglyceride content and higher large-VLDL proportion (p<0.05). The increase in FFA correlated with VLDL mass (r=0.36; p=0.009), VLDL particle number (r=0.45; p=0.0006) and large-VLDL proportion (r=0.32; p=0.02). MetS patients showed a decrease in ADP (7.4±4.8 vs. 15.5±7.2 μg/mL, p=0.01) and in LPL activity (p=0.01), that positively correlated between them (r=0.38; p=0.01; adjusted by HOMA-IR and waist: β=0.35; p=0.02). ADP inversely correlated with FFA and large-VLDL% (p<0.03). It can be concluded that in MetS, decreased ADP would favour the secretion of triglyceride over-enriched and larger VLDL particles, and also would delay VLDL catabolism mediated by LPL, resulting in the accumulation of altered VLDL with atherogenic characteristics.

O objetivo do trabalho foi avaliar se a redução da adiponectina (ADP) na síndrome metabólica (SM), afeta as características aterogênicas das VLDL. Foram estudados 45 indivíduos com SM e 15 controles saudáveis. Em jejum, foi medido em soro o perfil lipídico, ácidos graxos livres (AGL) e ADP. Foram isoladas as VLDL (d <1,006 g / L) caracterizando-as em relação a sua composição química e tamanho (HPLC- exclusão molecular). No plasma pós-heparina foi medida a atividade da lipoproteína lipase (LPL). Em indivíduos com SM, as VLDL apresentaram aumento de massa, número de partículas, conteúdo de triglicerídeos -VLDL e maior proporção de VLDL grandes (p<0,05). O aumento de AGL correlacionou com a massa de VLDL (r=0,36; p=0,009), número de partículas -VLDL (r=0,45; p=0,0006) e percentual -VLDL grandes (r=0,32; p=0,02). A SM mostrou uma diminuição em ADP (7,4±4,8 vs. 15,5±7,2 μg/mL, p=0,01) e em atividade de LPL (p=0,01), que correlacionaram entre eles (r=0,38; p=0,01; ajustada por HOMA-IR e cintura: β=0,35; p=0,02). A ADP correlacionou em forma negativa com AGL e %-VLDL grandes (p<0,03). A conclusão é que em indivíduos com SM, a diminuição da ADP iria favorecer a secreção de VLDL super-enriquecidas em triglicerídeos e de maior tamanho, e também atrasaria o catabolismo das VLDL mediado por LPL, resultando na acumulação de VLDL alteradas em circulação com características aterogênicas.

Alterations in triglyceride rich lipoproteins are related to endothelial dysfunction in metabolic syndrome.

UNLABELLED: Our aim was to analyze the effect of circulating triglyceride rich lipoprotein (TRL) on endothelial function in metabolic syndrome (MetS). METHODS: We studied 40 patients with MetS (ATPIII), divided into those presenting normal endothelial function (n=19) and those with endothelial dysfunction (n=21) by means of the evaluation of pulse wave velocity, before and after brachial artery ischemia. In fasting serum we measured lipid and lipoprotein profile, insulin and glucose (HOMA-IR). Moreover, isolated TRL (d<1006g/l) were chemically characterized. In parallel, using randomly selected TRL from MetS patients with endothelial dysfunction (n=6) and MetS patients with normal endothelial function (n=6), the ability of TRL to inhibit ACh-induced vasorelaxation (10(-9)-10(-5)mM) on aortic rings previously pre-contracted by noradrenaline (10(-8)mM) was evaluated. RESULTS: Interestingly, TRL isolated from MetS patients presenting endothelial dysfunction showed triglyceride over-enrichment (59.1±4.8 vs. 54.1±4.7%; p=0.04), even after adjusting by potential confounders (p=0.05). In addition, while TRL resulting from both MetS groups significantly inhibited endothelium dependent vasorelaxation (p<0.001), TRL from MetS patients with endothelial dysfunction showed a strong tendency to a greater inhibition of vasorelaxation (p=0.06). Moreover, TRL-triglyceride (%) showed a strong tendency to correlate with the grade of vasorelaxation inhibition exerted by TRL (r=0.60; p=0.05). CONCLUSION: These results, taken together, would allow inferring for the first time that the predominance of triglyceride over-enriched TRL in circulation in MetS would induce endothelial dysfunction, contributing to the inherent cardiovascular risk of MetS.

Atherogenic Lipoproteins in Subclinical Hypothyroidism and Their Relationship with Hepatic Lipase Activity: Response to Replacement Treatment with Levothyroxine.

BACKGROUND: Qualitative lipoprotein changes, such as an increase in fasting remnants, are reported in subclinical hypothyroidism (SCH). It was hypothesized that such changes are due to reduced hepatic lipase (HL) activity in SCH: HL is an enzyme regulated by thyroid hormones, and is involved in the degradation of triglyceride (TG)-rich remnants. This study aimed to quantify remnant-like lipoproteins (RLP), small dense LDL (sdLDL), and HL activity in women with SCH, and to assess these parameters after levothyroxine replacement therapy. METHODS: This was an observational cross-sectional study with a subsequent longitudinal follow-up. Findings in women with thyrotropin levels >4.5 mIU/L (SH group) were compared with age- and body mass index (BMI)-matched euthyroid women (control group). In addition, a subgroup analysis was undertaken in SCH women who chose to receive levothyroxine treatment (0.9 µg/kg/day) for 6 months. RLP was quantified by measuring cholesterol (RLP-C) and triglycerides (RLP-TG) after immunoaffinity chromatography, and sdLDL by automated standardized methods; HL activity was measured in post-heparin plasma. RESULTS: The SCH group included 37 women; 29 women were included in the control group. In addition, 22 women with SCH were included in the subgroup analysis (levothyroxine treatment). Significantly higher RLP values were observed in the SCH group than in the control group: RLP-C (median [range], mg/dL): 20.3 (5.8-66.8) versus 10.2 (2.7-36.3), p = 0.005; RLP-TG (mg/dL): 26.3 (3.2-123.3) versus 12.1 (2.5-61.6), p = 0.033. HL activity (mean ± standard deviation [SD], µmol free fatty acid/mL post-heparin plasma.h)-9.83 ± 4.25 versus 9.92 ± 5.20, p = 0.707-and sdLDL levels (mg/dL)-23.1 ± 10.7 versus 22.6 ± 8.4, p = 0.83-were similar. After levothyroxine, RLP-C decreased-21.5 (5.8-66.8) versus 17.2 (4.1-45.6), p = 0.023-and HL increased-9.75 ± 4.04 versus 11.86 ± 4.58, p = 0.012-in the subgroup of SCH women. No changes in sdLDL were observed. CONCLUSIONS: Women with SCH have higher RLP levels than matched controls do, but their RLP-C levels decrease significantly following levothyroxine therapy. Furthermore, HL activity also increases after levothyroxine therapy and can be interpreted as a possible explanation for the decrease in RLP-C.

Increased cholesterol efflux capacity in metabolic syndrome: Relation with qualitative alterations in HDL and LCAT.

BACKGROUND: Metabolic syndrome (MetS) is associated with changes in HDL levels, composition and sub-fraction profile. Whether these alterations affect HDL anti-atherogenic function, specifically measured as its capacity to perform cholesterol efflux, is not yet clearly known. OBJECTIVE: To evaluate the relation between serum cholesterol efflux capacity and the changes in HDL composition and sub-fraction profile in MetS. METHODS: In 35 non-treated MetS patients and 15 healthy controls, HDL mediated cholesterol efflux was measured as the ability of apoB-depleted serum to accept cholesterol from cholesterol-loaded BHK cells expressing either ABCA1 or ABCG1. Additionally we determined: lipid profile, HDL sub-fractions (NMR) and LCAT mass (ELISA). Isolated HDL (δ:1.063-1.210 g/mL) was chemically characterized. Pre-ß1-HDL was determined by 2D-electrophoresis in a sub-group of MetS and controls (n = 6 each). RESULTS: Surprisingly, MetS patients presented higher ABCA1 mediated cholesterol efflux (10.4 ± 1.8 vs. 8.7 ± 0.3%; p = 0.0001), without differences in ABCG1 efflux. In MetS, HDL showed reduction in particle size and number (p < 0.02) and lower large/small HDL ratio (p = 0.05), as well as triglyceride enrichment (p = 0.0001). Pre-ß1-HDL was increased in MetS (p = 0.048) and correlated with ABCA1-cholesterol efflux (r = 0.64; p = 0.042). LCAT mass showed a tendency to reduction in MetS (p = 0.08), and inversely correlated with ABCA1-cholesterol efflux (r = -0.51; p = 0.001), independently of obesity and insulin-resistance (ß = -0.40, p = 0.034). CONCLUSION: This is the first description of ABCA1 mediated cholesterol efflux in MetS. Regardless the reduced HDL-cholesterol, in vitro cholesterol efflux capacity by ABCA1 was enhanced, linked to increased pre-ß1-HDL and slightly reduced in LCAT mass that would probably reflect a delay in reverse cholesterol transport occurring in MetS.

Overproduction of altered VLDL in an insulin-resistance rat model: influence of SREBP-1c and PPAR-X / Sobreproducción de VLDL alteradas en un modelo de insulinorresistencia de rata: influencia de SREBP-1c y PPAR-x

Background: In insulin-resistance, VLDL presents alterations that increase its atherogenic potential. The mechanism by which insulin-resistance promotes the production of altered VLDL is still not completely understood. The aim of this study was to evaluate the relationship between the expression of sterol regulatory element binding protein 1c (SREBP-1c) and of peroxisome proliferator-activated receptor-α (PPAR-α), with the features of composition and size of VLDL in an insulin-resistance rat model induced by a sucrose rich diet (SRD). Methods: The study was conducted on 12 male Wistar rats (180 g) receiving SRD (12 weeks) and 12 controls. Lipid profile, free fatty acids, glucose, and insulin were measured. Lipid content in liver and visceral fat were assessed. Isolated VLDL (d < 1.006 g/ml) was characterized by its chemical composition and size by HPLC. The respective hepatic expression of SREBP-1c and PPAR-α was determined (Western blot). Results: As expected, SRD had elevated triglycerides (TG), free fatty acids and insulin levels, and decreased HDL-cholesterol (p < 0.05), together with augmented hepatic and visceral fat (p < 0.05). SRD showed higher VLDL total mass - with increased TG content - and predominance of large VLDL (p < 0.05). SRD showed an increase in SREBP-1c (precursor and mature forms) and decreased PPAR-α expression (p < 0.045). SREBP-1c forms were positively associated with VLDL total mass (p < 0.04), VLDL-TG% (p < 0.019), and large VLDL% (p < 0.002). On the other hand, PPAR-α correlated negatively with VLDL total mass (p = 0.05), VLDL-TG% (p = 0.005), and large VLDL% (p = 0.002). Conclusions: Insulin-resistance, by coordinated activation of SREBP-1c and reduction of PPAR-α, could promote the secretion of larger and TG over-enriched VLDL particles, with greater atherogenic capacity

Introducción: En la insulinorresistencia, la VLDL presenta alteraciones que aumentan su potencial aterogénico. El mecanismo por el cual la insulinorresistencia promueve la producción de VLDL alteradas aún no se comprende completamente. Objetivo: evaluar la relación entre la expresión de la proteína ligadora de elementos reguladores de esteroles-1c (SREBP-1c) y de los receptores activados por factores de proliferación peroxisomal-α (PPAR-α) con las características de composición y tamaño de VLDL en un modelo animal de insulinorresistencia inducida por dieta rica en sacarosa (DRS). Métodos: Estudiamos 12 ratas macho Wistar (180 g) que recibieron DRS (12 semanas) y 12 controles. Se midieron el perfil lipídico, los ácidos grasos libres, la glucosa y la insulina. Se cuantificaron el contenido lipídico hapático y la grasa visceral. Se caracterizó la VLDL aislada (d < 1,006 g/ml) en composición química y tamaño (HPLC). Se determinó la expresión hepática de SREBP-1c y PPAR-α (Western-blot). Resultados: Esperadamente, el grupo DRS presentó elevación de triglicéridos (TG), ácidos grasos libres e insulina y disminución de colesterol-HDL (p < 0,05), junto con incremento de grasa hepática y visceral (p < 0,05). La DRS mostró una mayor masa total de VLDL —con mayor contenido de TG— y predominio de VLDL grandes (p < 0,05). DRS presentó expresión incrementada de SREBP-1c (precursor y maduro) y disminuida de PPAR-α (p < 0,045). Ambas formas de SREBP-1c se correlacionaron positivamente con masa total de VLDL (p < 0,04), TG%-VLDL (p < 0,019) y VLDL-grande % (p < 0,002). Mientras que PPAR-α se correlacionó negativamente con masa total de VLDL (p = 0,05), TG %-VLDL (p = 0,005) y VLDL-grande % (p = 0,002). Conclusiones: La insulinorresistencia, mediante una coordinada activación de SREBP-1c y reducción de PPAR-α, promovería la secreción de partículas de VLDL grandes y sobreenriquecidas en TG, con mayor capacidad aterogénica

Overproduction of altered VLDL in an insulin-resistance rat model: Influence of SREBP-1c and PPAR-α.

BACKGROUND: In insulin-resistance, VLDL presents alterations that increase its atherogenic potential. The mechanism by which insulin-resistance promotes the production of altered VLDL is still not completely understood. The aim of this study was to evaluate the relationship between the expression of sterol regulatory element binding protein 1c (SREBP-1c) and of peroxisome proliferator-activated receptor-α (PPAR-α), with the features of composition and size of VLDL in an insulin-resistance rat model induced by a sucrose rich diet (SRD). METHODS: The study was conducted on 12 male Wistar rats (180g) receiving SRD (12 weeks) and 12 controls. Lipid profile, free fatty acids, glucose, and insulin were measured. Lipid content in liver and visceral fat were assessed. Isolated VLDL (d<1.006g/ml) was characterized by its chemical composition and size by HPLC. The respective hepatic expression of SREBP-1c and PPAR-α was determined (Western blot). RESULTS: As expected, SRD had elevated triglycerides (TG), free fatty acids and insulin levels, and decreased HDL-cholesterol (p<0.05), together with augmented hepatic and visceral fat (p<0.05). SRD showed higher VLDL total mass - with increased TG content - and predominance of large VLDL (p<0.05). SRD showed an increase in SREBP-1c (precursor and mature forms) and decreased PPAR-α expression (p<0.045). SREBP-1c forms were positively associated with VLDL total mass (p<0.04), VLDL-TG% (p<0.019), and large VLDL% (p<0.002). On the other hand, PPAR-α correlated negatively with VLDL total mass (p=0.05), VLDL-TG% (p=0.005), and large VLDL% (p=0.002). CONCLUSIONS: Insulin-resistance, by coordinated activation of SREBP-1c and reduction of PPAR-α, could promote the secretion of larger and TG over-enriched VLDL particles, with greater atherogenic capacity.