A influência do exercício físico de moderada intensidade e da suplementação com ácido lipóico sobre a função cardíaca, a bioquímica sanguínea e a angiogênese em miocárdio de Rattus norvegicus

Atualmente o exercício físico vem sendo utilizado com intuito de redução de massa corporal, em especial de massa gorda. Entretanto cresce o número de indivíduos que, associado ao exercício físico, utiliza substâncias com característica lipolítica, como é o caso do ácido lipóico. Tanto o exercício físico, quanto a utilização de suplementação com ácido lipóico são responsáveis por remodelagem vascular (devido à interferência no processo de angiogênese) e modificação de fatores de risco cardiovascular (como hipertensão e lipídeos sanguíneos elevados). Desta forma, o presente estudo buscou analisar a influência do exercício físico de moderada intensidade e da suplementação com ácido lipóico sobre a frequência cardíaca, pressão arterial, bioquímica sanguínea e angiogênese no músculo cardíaco e no músculo esquelético de ratos Wistar. Foram utilizados 80 ratos Wistar, divididos em quatro grupos: controle, ácido lipóico (LA), exercício (E) e associação (ELA). Os animais foram submetidos a um programa de adaptação e treinamento de natação (9 e 17 semanas) com um aumento progressivo no tempo natação (até 1h/dia) e intensidade de carga (até 5% do peso corporal). Os animais receberam ácido lipóico 5 vezes por semana (da 10ª à 17ª semana), 60 mg / Kg / dia. O exercício crônico de intensidade moderada promoveu bradicardia, mas sua associação com a suplementação de ácido lipóico interrompeu este benefício. A suplementação com LA mostrou-se eficaz em melhorar o perfil lipídico, mas associado ao exercício não apresentou redução. A angiogênese foi aumentada no coração e gastrocnêmio dos animais exercitados, a largura da fibra de E, LA e ELA foi reduzida no coração, enquanto no gastrocnêmio apresentaram um aumento na largura das fibras apenas por LA e ELA. A espessura do ventrículo esquerdo diminuiu no grupo E, enquanto que a área da câmara do ventrículo esquerdo, e os níveis de VEGF circulantes, não mostraram nenhuma diferença significativa. Foi observada uma interação negativa entre o exercício físico e a suplementação com ácido lipóico (supressão da bradicardia do exercício de um lado, e a perda da adaptação do perfil lipídico induzido por suplementação de AL por outro lado). Este estudo mostra pela primeira vez, a interação entre o exercício crônico de intensidade moderada e a suplementação com ácido lipóico sobre a remodelação cardíaca e angiogênese, confirmando os benefícios da prática física em melhorar o fornecimento de sangue do músculo, que não foi afetado pelo consumo de ácido lipóico. O ácido lipóico em animais não treinados não foi capaz de estimular a 9 angiogênese cardíaca e ao contrário mostram uma tendência para a redução dos novos vasos.

The influence of ApoE genotype on the lipid profile and lipoproteins during normal pregnancy in a Southern African population.

Background: Pregnancy is associated with increases in fasting triglycerides and total cholesterol.1 ApoE isoforms are known to influence the concentration of cholesterol, with apoE2 homozygosity lowering and apoE4 homozygosity raising the cholesterol concentration compared with E3 homozygosity.2 The lipid profiles ApoE status and prevalence of small dense LDL species were evaluated for subjects attending an antenatal clinic. Results: Samples from 690 women aged between 16 and 42 years of age were analyzed during and after pregnancy. The fasting plasma triglyceride concentration (in mmol/L) was significantly higher in pregnancy (median = 1.5, IQR 1.0-2.0 vs median = 0.6, IQR 0.5-0.8 respectively, p < 0.0001). Similarly, the total cholesterol (in mmol/L) was increased during pregnancy (median=4.1, IQR 3.6-4.7 vs median 3.5, IQR 3.1-3.5, respectively p=0.0167). The median LDL cholesterol and HDL cholesterol did not change. Higher proportions of small density LDL species were seen during pregnancy compared to after pregnancy. The distribution of the LDL species during pregnancy and 6 weeks post-partum were significantly different p<0.0001 with the smaller species being much higher during pregnancy. Conclusion: ApoE4 genotype was associated with increased total cholesterol and LDL cholesterol concentrations during pregnancy. Pregnancy results in a reversible remodeling of LDL to smaller species, the significance of which is unknown but may indicate a predisposition to atherosclerosis

Effects of oat bran and nutrition counseling on the lipid and glucose profile and anthropometric parameters of hypercholesterolemia patients

Background: In order to prevent chronic, non communicable disease, it is essential that lifestyle is modified to include a diet high in fiber. Aim: To assess the effect oat bran (OB) in conjunction with nutrition counseling (NC) have on lipid and glucose profile, anthropometric parameters, quality of diet, and ingestion of ultraprocessed foods (UPF) and additives in hypercholesterolemia sufferers. Method: This was a 90-day, double-blind, placebo-controlled, block-randomized trial undertaken on 132 men and women with LDL-c ≥ 130 mg/dL. The participants were sorted into two groups: OB Group (OBG) and Placebo Group (PLG), and were given NC and 40g of either OB or rice flour, respectively. Lipid and glucose profile were assessed, as were the anthropometric data, quality of diet (Diet Quality Index revised for the Brazilian population - DQI-R) and whether or not UPF or additives were consumed. Results: Both groups showed a significant decrease in anthropometric parameters and blood pressure, as well as a significant reduction in total and LDL cholesterol. There was also an improvement in DQI-R in both groups and a decrease in consumption of UPF. Blood sugar, HOMA-IR and QUICKI values were found to be significantly lower only in the OBG. Conclusion: Our findings in lipid profile and anthropometric parameters signify that NC has a beneficial effect, which is attributable to the improved quality of diet and reduced consumption of UPF. Daily consumption of 40 g of OB was found to be of additional benefit, in decreasing insulin-resistance parameters.

Similarities between the lipid proile of Mexican patients with lupus and the general population

Premature cardiovascular events have been observed in systemic lupus erythematosus (SLE) patients, but the reason for this accelerated process is still debatable; although traditional risk factors are more prevalent in such patients than in the general population, the do not seem to fully explain that enhanced risk. One of the most important conditions is a proatherogenic lipid proile. There is not enough data about it in Mexican SLE patients. Objective: To establish the differences in the lipid proiles between Mexican patients with SLE and the general population. Material and methods: Observational, transversal, descriptive and comparative study, between SLE patients and age-sex-matched healthy volunteers. We performed a full lipid proile (by spectrophotometry) 14 hours of fast. The results obtained were analyzed by the statistical program SPSS® Statistics version 17. Results: We studied the full lipid proiles of 138 subjects, 69 with a diagnosis of SLE and 69 agesex- matched healthy volunteers; 95.7% were females and 4.3% males. Average age was 30 years; average body mass index (BMI) 25.96 ± 5.96 kg/m² in SLE patients and 26.72 ± 4.36 kg/m² in the control group (p = 0.396). Average of total cholesterol 156 mg/dl in the SLE patients and 169.4 mg/dl in the control group (p =0.028); average of low density lipoprotein (LDL) cholesterol 85.27 mg/dl in the SLE patients and 97.57 mg/dl in the control group (p = 0.023). Conclusions: We did not ind statistical differences in the lipid proiles among patients and healthy volunteers, which could explain increased cardiovascular morbidity and mortality observed in SLE patients

Aortic Intima-Media Thickness and Mean Platelet Volume in Children With Type 1 Diabetes Mellitus

Background: Diabetes mellitus type 1 is the most common endocrine metabolic disorder occurring in childhood and adolescence due to the autoimmune destruction of pancreatic beta cells as a result of various environmental factors interacting with an underlying genetic predisposition. Diabetes is a risk factor for early onset atherosclerosis, and the high mortality rate seen in these patients is partially related to cardiovascular diseases. Objectives: This study was conducted to compare mean platelet volume as a marker of early atherosclerosis with aortic intima-media thickness in children with type 1 diabetes and to identify its correlation with known cardiovascular risk factors. Patients and Methods: The study included 27 patients between age range of 6 and 17 years that were diagnosed with type 1 diabetes and 30 healthy children of the same age range who did not have any chronic disease. In both groups, we used the color Doppler ultrasound to measure children’s aortic intima-media thickness and identify their mean platelet volumes. Results: There was no significant difference between the groups regarding gender distribution, age, High-Density Lipoprotein (HDL) and Low-Density Lipoprotein (LDL) cholesterol levels (P > 0.05). Also no significant difference could be documented between the patient and control groups regarding the aortic intima-media thickness and mean platelet volume (P > 0.05). However, there was a significant correlation between aortic intima-media thickness and mean platelet volume (r = 0.351; P < 0.05). Conclusions: In the present study, there was no evidence of early atherosclerosis in children with type 1 diabetes. However, mean platelet volume having a significant correlation with aortic intima-media thickness may be useful as an early marker of atherosclerosis.

Association of the TNF-alpha -308 G/A polymorphisms with metabolic responses secondary to a high protein/low carbohydrate versus a standard hypocaloric diet

Background: Mutation analysis has identified a G-> A transition in the promoter region of TNF-alpha gene at position -308 (rs1800629). Objective: The aim of our study was to investigate the influence of polymorphism in -308 GA promoter variant of the TNF alpha gene on metabolic response and weight loss secondary to two hypocaloric diets. Method: A sample of 283 obese subjects was enrolled in a consecutive prospective way. In the basal visit, patients were randomly allocated during 9 months to diet HP (high protein/low carbohydrate hypocaloric diet) and diet S (standard hypocaloric diet). Results: There were no significant differences between the positive effects on weight loss in either genotype group with both diets. With both diets and only in wild genotype (diet HP vs. diet S), total cholesterol (-9.1 ± 3.4 mg/dL vs. -6.9 ± 2.0 mg/dL; p > 0.05), LDL cholesterol (-9.0 ± 2.9 mg/dL vs. -6.5 ± 2.1 mg/dL; p > 0.05) and triglycerides (-23.1 ± 5.1 mg/dL vs. -12.3 ± 4.8 mg/dL; p < 0.05) decreased. The improvement in triglycerides was higher in subjects without A allele. With diet HP and only in wild genotype, insulin levels (-3.1 ± 1.8 UI/L; p < 0.05) and HOMA-R (-0.8 ± 0.1 units; p < 0.05) decreased. Conclusion: Carriers of -308 GG promoter variant of TNF-alpha gene have a better metabolic response than -308 GA obese with a high protein hypocaloric diet.

Fiber, a component for health gastrointestinal endocrine system

Dietary fiber was classified according to its solubility in an attempt to relate physiological effects to chemical types of fiber. Soluble fibers (B-glucans, gums, wheat dextrin, psyllium, pectin, inulin) were considered to have benefits on serum lipids, while insoluble fibers (cellulose, lignin, pectins, hemicelluloses) were linked with laxation benefits. More important characteristics of fiber in terms of physiological benefits are viscosity and fermentability. Viscous fibers (pectins, B-glucans, gums, psyllium) are those that have gel-forming properties in the intestinal tract, and fermentable fibers (wheat dextrin, pectins, B-glucans, gum, inulin) are those that can be metabolized by colonic bacteria. Objective: To summarize the beneficial effects of dietary fiber, as nutraceuticals, in order to maintain a healthy gastrointestinal system. Methods: Our study is a systematic review. Electronic databases, including PubMed, Medline, with supplement of relevant websites, were searched. We included randomized and non-randomized clinical trials, epidemiological studies (cohort and case-control). We excluded case series, case reports, in vitro and animal studies. Results: The WHO, the U.S. Food and Drug Administration (FDA), the Heart Foundation and the Romanian Dietary Guidelines recommends that adults should aim to consume approximately 25–30 g fiber daily. Dietary fiber is found in the indigestible parts of cereals, fruits and vegetables. There are countries where people don’t eat enough food fibers, these people need to take some kind of fiber supplement. Evidence has been found that dietary fiber from whole foods or supplements may (1) reduce the risk of cardiovascular disease by improving serum lipids and reducing serum total and low-density lipoprotein (LDL) cholesterol concentrations, (2) decreases the glycaemic index of foods, which leads to an improvement in glycemic response, positive impact on diabetes, (3) protect against development of obesity by increasing satiety hormone leptin concentrations, (4) reduced risk of developing colorectal cancer by normalizes bowel movements, improve the integrity of the epithelial layer of the intestines, increase the resistance against pathogenic colonization, have favorable effects on the gut microbiome, wich is the second genomes of the microorganisms, (5) have a positive impact on the endocrine system by gastrointestinal polypeptide hormonal regulation of digestion, (6) have prebiotic effect by short-chain fatty acids (SCFA) production; butyrate acid is the preferred energy source for colonic epithelial cells, promotes normal cell differentiation and proliferation, and also help regulate sodium and water absorption, and can enhance absorption of calcium and other minerals. Although all prebiotics are fiber, not all fiber is prebiotic. This generally refers to the ability of a fiber to increase the growth of bifidobacteria and lactobacilli, which are beneficial to human health, and (7) play a role in improving immune function via production of SCFAs by increases T helper cells, macrophages, neutrophils, and increased cytotoxic activity of natural killer cells. Conclusion: Fiber consumption is associated with high nutritional value and antioxidant status of the diet, enhancing the effects on human health. Fibers with prebiotic properties can also be recommended as part of fiber intake. Due to the variability of fiber’s effects in the body, it is important to consume fiber from a variety of sources. Increasing fiber consumption for health promotion and disease prevention is a critical public health goal.

Programme d’interventions nutritionnelles centrées sur une alimentation végétale minimalement transformée : évaluation des effets et exploration des déterminants influençant les choix alimentaires chez des adultes à risque de maladies cardiovasculaires

Résumé : Contexte: Les maladies cardiovasculaires (MCV) sont un enjeu contemporain de santé publique. Or, des recherches cliniques démontrent que certaines interventions sont efficaces dans leur traitement et prévention. Il s’agit d’interventions nutritionnelles éducatives priorisant des aliments végétaux minimalement transformés (VMT). Ces interventions promeuvent l’adoption de postures alimentaires se caractérisant par la consommation à volonté d’une grande variété d’aliments d’origine végétale (e.g. légumineuses, céréales entières, fruits, légumes) et par une diminution de la consommation d’aliments d’origine animale (e.g. viandes, œufs et produits laitiers) et ultra-transformés (e.g. riches en sucres, sel ou gras, et faibles en fibres). Objectifs: À l’aide d’un devis mixte concomitant imbriqué, nous avons évalué les effets d’un programme d’interventions éducatives visant à augmenter la consommation de VMT chez des adultes à risque de MCV et exploré les déterminants des modifications comportementales observées. Méthodologie : Divers paramètres physiologiques et anthropométriques ont été mesurés pré-post programme (n = 72) puis analysés avec un test t pour échantillons appariés ou un test signé des rangs de Wilcoxon. D’autre part, 10 entretiens semi-dirigés ont été réalisés post-programme et soutenus par un guide d’entretien basé sur le Food Choice Process Model. Les verbatims intégraux ont été codés selon la méthode d’analyse thématique. Résultats : Après 12 semaines, le poids (-10,5 lb, IC 95 %: 9,0-12,0), le tour de taille (-7,4 cm, IC 95 %:6,5-8,4), la tension artérielle diastolique (-3,2 mmHg, IC 95 %: 0,1-6,3), le cholestérol total (-0,87 mmol/ L, IC 95 %:0,57-1,17), le cholestérol LDL (-0,84 mmol/ L, IC 95 %: 0,55-1,13) et l’hémoglobine glyquée (-1,32 %, IC 95 %:-0,17-2,80) se sont significativement améliorés. L’analyse thématique des données qualitatives révèle que le programme, par la stimulation de valeurs de santé, d’éthique et d’intégrité, favorise la transformation des choix alimentaires vers une posture davantage axée sur les VMT durant une période clé du parcours de vie (i.e. pré-retraite). D’autres déterminants pouvant favoriser l’adoption d’une alimentation VMT ont été identifiés, dont les bénéfices importants observables à court terme, l’absence de restriction à l’égard de la quantité d’aliments VMT et le développement de compétences de planification dans l’acquisition et la préparation des aliments. Conclusion : Une intervention priorisant les VMT permet d’améliorer le profil cardiométabolique d’individus pré-retraités en raison de ses caractéristiques intrinsèques, mais aussi parce qu’elle modifie les valeurs impliquées dans les choix alimentaires.

Élucidation et identification des différents interacteurs impliqués dans le mécanisme de régulation du LDLR par la protéine PCSK9

Résumé : Les maladies cardiovasculaires représentent la principale cause de mortalité mondiale, soit le tiers des décès annuels selon l’Organisation mondiale de la Santé. L’hypercholestérolémie, caractérisée par une élévation des niveaux plasmatiques de lipoprotéines de faible densité (LDL), est l’un des facteurs de risque majeur pour les maladies cardiovasculaires. La proprotéine convertase subtilisine/kexine type 9 (PCSK9) joue un rôle essentiel dans l’homéostasie du cholestérol sanguin par la régulation des niveaux protéiques du récepteur LDL (LDLR). PCSK9 est capable de se lier au LDLR et favorise l’internalisation et la dégradation du récepteur dans les lysosomes. L’inhibition de PCSK9 s’avère une cible thérapeutique validée pour le traitement de l’hypercholestérolémie et la prévention des maladies cardiovasculaires. Par contre, plusieurs mécanismes responsables de la régulation et la dégradation du complexe PCSK9-LDLR n’ont pas encore été complètement caractérisés comme la régulation par la protéine annexin A2 (AnxA2), un inhibiteur endogène de PCSK9. De plus, plusieurs évidences suggèrent la présence d’une ou plusieurs protéines, encore inconnues, impliquées dans le mécanisme d’action de PCSK9. Celles-ci pourraient réguler l’internalisation et le transport du complexe PCSK9-LDLR vers les lysosomes. Les objectifs de cette thèse sont de mieux définir le rôle et l’impact de l’AnxA2 sur la protéine PCSK9 en plus d’identifier de nouveaux partenaires d’interactions de PCSK9 pour mieux caractériser son mécanisme d’action sur la régulation des niveaux de LDLR. Nous avons démontré que l’inhibition de PCSK9 par l’AnxA2 extracellulaire s’effectue via sa liaison aux domaines M1+M2 de la région C-terminale de PCSK9 et nous avons mis en évidence les premières preuves d’un contrôle intracellulaire de l’AnxA2 sur la traduction de l’ARNm de PCSK9. Nos résultats révèlent une liaison de l’AnxA2 à l’ARN messager de PCSK9 qui cause une répression traductionnelle. Nous avons également identifié la protéine glypican-3 (GPC3) comme un nouveau partenaire d’interaction extracellulaire avec le PCSK9 et intracellulaire avec le complexe PCSK9-LDLR dans le réticulum endoplasmique des cellules HepG2 et Huh7. Nos études démontrent que GPC3 réduit l’activité extracellulaire de PCSK9 en agissant comme un compétiteur du LDLR pour la liaison avec PCSK9. Une meilleure compréhension des mécanismes de régulation et de dégradation du complexe PCKS9-LDLR permettra de mieux évaluer l’impact et l’efficacité des inhibiteurs de la protéine PCSK9.

Effect of Fatty Acids Fiber Concentration in Broiler Ration to Cholesterol, HDL and LDL Blood Serum

Cholesterol, HDL (High Density Lipoprotein) and LDL (Low Density Lipoprotein) in blood serum of broiler could can be controlled by food manipulation using different fatty acids and fiber content in ration. This research was planned to study the influence of fat i.e. cis-trans fatty acids and raw fiber content on feed to cholesterol, HDL and LDL biosynthesizing broiler blood serum. The research model was experimental and the design used was Completely Randomized Design in factorial pattern 2 x 3. The first factor was type of fat (L) : L1= cis fatty acid and L2 = trans fatty acid. The second factor was fiber content in feed (S) i.e. S1 = 5% ; S2 = 7%, and S3 = 9%. Each treatment was repeated four times, it means 24 observation. Variables observed were : cholesterol, HDL, LDL concentration in blood serum of broiler. The result indicated that the use of 5 % palm kernel oil and 5 % tallow fat in feed containing 5 %, 7 % and 9 % fiber respectively have unsignificant result (P>0.01) to cholesterol and LDL blood serum of broiler, but have significant to HDL concentration (P<0.01). The average cholesterol of blood serum was between 76.46 mg/dl (L2S3) to 99.88 mg/dl (control), HDL concentration was 21.19 mg/dl (L2S1) to 38.85 mg/dl (control), and LDL concentration was 46.83 mg/dl (L2S2) to 61.14 mg/dl (control). It can be concluded that feeding with far in the form of cis (palm kernel oil) or trans (tallow) when combined with proporsional fiber addition can be used as feed because it does not increase the cholesterol and LDL in broiler blood. The reduction of cholesterol as much as 23.53 % in control feed was found in treatment with 5 % tallow addition in combination with 9 % raw fiber content, HDL concentration was higher in treatment with palm kernel oil compared to tallow addition. (Animal Production 7(1): 27-33 (2005) Key Words : Cholesterol, HDL, LDL, Cis Fatty Acid, Trans Fatty Acid

Cellular Cholesterol Accumulation and Egress from Endosomal Compartments

One of the most important factors determining the development of atherosclerosis is the amount of LDL particles in the circulation. In general, LDL particles are clinically regarded as “bad cholesterol” since these particles get entrapped within the vascular wall, leading to atherosclerosis. Circulating HDL particles are conversely regarded as “good cholesterol” because of their ability to transport cholesterol from peripheral tissues to the liver for secretion as bile salts. Once inside the artery wall LDL particles are engulfed by macrophages, resulting in macrophage foam cells. If the macrophage foam cells are not able to efflux the cholesterol back into the bloodstream, the excessive cholesterol ultimately leads to cell death, and the deposition of cellular debris within the atherosclerotic lesion. The cells ability to secrete cholesterol is mainly dependent on the ABCA1 transporter (ATP-binding cassette transporter A1) which transfers cellular cholesterol to extracellular apoA-I (apolipoprotein A-I) particles, leading to the generation of nascent HDL particles. The process of atherosclerotic plaque development is therefore to a large extent a cellular one, in which the capacity of the macrophages in handling the excessive cholesterol load determines the progression of lesion development. In this work we have studied the cellular mechanisms that regulate the trafficking of LDL-derived cholesterol from endosomal compartments to other parts of the cell. As a basis for the study we have utilized cells from patients with Niemann-Pick type C disease, a genetic disorder resulting from mutations in the NPC1 and NPC2 genes. In these cells, cholesterol is entrapped within the endosomal compartment, and is not available for efflux. By identifying proteins that bypass the cholesterol trafficking defect, we were able to identify the small GTPase Rab8 as an important protein involved in ABCA1 dependent cholesterol efflux. In the study, we show that Rab8 regulates cholesterol efflux in human macrophages by facilitating intracellular cholesterol transport, as well as by regulating the plasma membrane availability of ABCA1. Collectively, these results give new insight in to atherosclerotic lesion development and intracellular cholesterol processing.

High-density lipoprotein 17beta-estradiol fatty acyl esters and phytoestrogens : Impact on reverse cholesterol transport and women's cardiovascular health

Reverse cholesterol transport (RCT) is an important function of high-density lipoproteins (HDL) in the protection of atherosclerosis. RCT is the process by which HDL stimulates cholesterol removal from peripheral cells and transports it to the liver for excretion. Premenopausal women have a reduced risk for atherosclerosis compared to age-matched men and there exists a positive correlation for serum 17β-estradiol (E2) and HDL levels in premenopausal women supporting the role of E2 in atherosclerosis prevention. In premenopausal women, E2 associates with HDL as E2 fatty acyl esters. Discovery of the cellular targets, metabolism, and assessment of the macrophage cholesterol efflux potential of these HDL-associated E2 fatty acyl esters were the major objectives of this thesis (study I, III, and IV). Soy phytoestrogens, which are related to E2 in both structure and function, have been proposed to be protective against atherosclerosis but the evidence to support these claims is conflicting. Therefore, another objective of this thesis was to assess the ability of serum from postmenopausal women, treated with isoflavone supplements (compared to placebo), to promote macrophage cholesterol efflux (study II). The scope of this thesis was to cover the roles that HDL-associated E2 fatty acyl esters have in the cellular aspects of RCT and to determine if soy isoflavones can also influence RCT mechanisms. SR-BI was a pivotal cellular receptor, responsible for hepatic and macrophage uptake and macrophage cholesterol efflux potential of HDL-associated E2 fatty acyl esters. Functional SR-BI was also critical for proper LCAT esterification activity which could impact HDL-associated E2 fatty acyl ester assembly and its function. In hepatic cells, LDL receptors also contributed to HDL-associated E2 fatty acyl esters uptake and in macrophage cells, estrogen receptors (ERs) were necessary for both HDL-associated E2 ester-specific uptake and cholesterol efflux potential. HDL-containing E2 fatty acyl esters (E2-FAE) stimulated enhanced cholesterol efflux compared to male HDL (which are deficient in E2) demonstrating the importance of the E2 ester in this process. To support this, premenopausal female HDL, which naturally contains E2, showed greater macrophage cholesterol efflux compared to males. Additionally, hepatic and macrophage cells hydrolyzed the HDL-associated E2 fatty acyl ester into unesterified E2. This could have important biological ramifications because E2, not the esterified form, has potent cellular effects which may influence RCT mechanisms. Lastly, soy isoflavone supplementation in postmenopausal women did not modulate ABCA1-specific macrophage cholesterol efflux but did increase production of plasma pre-β HDL levels, a subclass of HDL. Therefore, the impact of isoflavones on RCT and cardiovascular health needs to be further investigated. Taken as a whole, HDL-associated E2 fatty acyl esters from premenopausal women and soy phytoestrogen treatment in postmenopausal women may be important factors that increase the efficiency of RCT through cellular lipoprotein-related processes and may have direct implications on the cardiovascular health of women.

The role of phospholipid transfer protein and cholesteryl ester transfer protein in reverse cholesterol transport

In atherosclerosis, cholesterol accumulates in the vessel wall, mainly in the form of modified low-density lipoprotein (LDL). Macrophages of the vessel wall scavenge cholesterol, which leads to formation of lipid-laden foam cells. High plasma levels of high-density lipoprotein (HDL) protect against atherosclerosis, as HDL particles can remove peripheral cholesterol and transport it to the liver for excretion in a process called reverse cholesterol transport (RCT). Phospholipid transfer protein (PLTP) remodels HDL particles in the circulation, generating prebeta-HDL and large fused HDL particles. In addition, PLTP maintains plasma HDL levels by facilitating the transfer of post-lipolytic surface remnants of triglyceride-rich lipoproteins to HDL. Most of the cholesteryl ester transfer protein (CETP) in plasma is bound to HDL particles and CETP is also involved in the remodeling of HDL particles. CETP enhances the heteroexchange of cholesteryl esters in HDL particles for triglycerides in LDL and very low-density lipoprotein (VLDL). The aim of this thesis project was to study the importance of endogenous PLTP in the removal of cholesterol from macrophage foam cells by using macrophages derived from PLTP-deficient mice, determine the effect of macrophage-derived PLTP on the development of atherosclerosis by using bone marrow transplantation, and clarify the role of the two forms of PLTP, active and inactive, in the removal of cholesterol from the foam cells. In addition, the ability of CETP to protect HDL against the action of chymase was studied. Finally, cholesterol efflux potential of sera obtained from the study subjects was compared. The absence of PLTP in macrophages derived from PLTP-deficient mice decreased cholesterol efflux mediated by ATP-binding cassette transporter A1. The bone marrow transplantation studies showed that selective deficiency of PLTP in macrophages decreased the size of atherosclerotic lesions and caused major changes in serum lipoprotein levels. It was further demonstrated that the active form of PLTP can enhance cholesterol efflux from macrophage foam cells through generation of prebeta-HDL and large fused HDL particles enriched with apoE and phospholipids. Also CETP may enhance the RCT process, as association of CETP with reconstituted HDL particles prevented chymase-dependent proteolysis of these particles and preserved their cholesterol efflux potential. Finally, serum from high-HDL subjects promoted more efficient cholesterol efflux than did serum derived from low-HDL subjects which was most probably due to differences in the distribution of HDL subpopulations in low-HDL and high-HDL subjects. These studies described in this thesis contribute to the understanding of the PLTP/CETP-associated mechanisms underlying RCT.

Estudos dos polimorfismos dos genes da apolipoproteína E (ApoE) e do receptor de LDL (RLDL - A370T) em indivíduos jovens pertencentes ao estudo do Rio de Janeiro em seguimento de 28 Anos

Estudos demonstram a associação de alterações da apolipoproteína E (ApoE) e do receptor do LDL (RLDL) com a ocorrência de doenças cardiovasculares e dislipidemia. O objetivo principal deste trabalho foi investigar a associação entre genótipos diferenciais da ApoE e do RLDL com a persistência de alterações de variáveis lipídicas em indivíduos jovens acompanhados há 28 anos no Estudo do Rio de Janeiro (ERJ). Através de um estudo longitudinal, tipo coorte, investigou-se 56 indivíduos (35M) em três avaliações. Em A1 (13.301.53 anos), A2 (22.091.91 anos) e A3 (31.231.99). Nas três ocasiões foi realizada avaliação clínica. Em A2 e A3 foram dosados colesterol total, HDL, LDL e triglicerídeos. Em A3 acrescentou-se o estudo dos polimorfismos genéticos da ApoE e do RLDL. Os fragmentos de interesse neste estudo foram amplificados por PCR (polymerase chain reaction) e os genótipos foram identificados através de reações de restrição. As frequências genotípicas de ApoE foram ε3/ε3 (62,5%), ε3/ε4 (25%), ε2/ε3 (5,4%) ,ε2/ε4 (5,4%) e ε4/ε4 (1,8%) e para os genótipos de RLDL foram AA (85,7%), AT (12,5%) e TT (1,8%). O genótipo ε2/ε2 não foi observado. A análise da distribuição dos genótipos de ApoE segundo a permanência de dislipidemia mostrou que todos os indivíduos com genótipo de ApoE dos tipos ε2/ε4 e ε4/ε4 mantiveram pelo menos um lípide alterado em A2 e A3 entretanto, todos os indivíduos com genótipo de ApoE do tipo ε2/ε3 não apresentaram lípides alterados em A2 e A3. Para o genótipo do RLDL não houve diferença significativa. Quando analisadas isoladamente, não foi identificado nenhum resultado significativo em A2 e/ou A3 associado a estes genótipos. O polimorfismo do gene da ApoE esteve associado à permanência de dislipidemia em indivíduos jovens acompanhados em estudo de seguimento longitudinal

Human LDL Structural Diversity Studied by IR Spectroscopy

Lipoproteins are responsible for cholesterol traffic in humans. Low density lipoprotein (LDL) delivers cholesterol from liver to peripheral tissues. A misleading delivery can lead to the formation of atherosclerotic plaques. LDL has a single protein, apoB-100, that binds to a specific receptor. It is known that the failure associated with a deficient protein-receptor binding leads to plaque formation. ApoB-100 is a large single lipid-associated polypeptide difficulting the study of its structure. IR spectroscopy is a technique suitable to follow the different conformational changes produced in apoB-100 because it is not affected by the size of the protein or the turbidity of the sample. We have analyzed LDL spectra of different individuals and shown that, even if there are not big structural changes, a different pattern in the intensity of the band located around 1617 cm 21 related with strands embedded in the lipid monolayer, can be associated with a different conformational rearrangement that could affect to a protein interacting region with the receptor.