L'athérosclérose est un processus physiopathologique chronique impliqué dans la majorité des maladies cardio-vasculaires. Le développement des lésions d'athérosclérose est caractérisé par l'accumulation de lipides extra et intracellulaires dans la paroi artérielle à l'origine d'une forte réponse inflammatoire impliquant notamment les macrophages. Les macrophages sont considérés comme des acteurs clés dans le développement des plaques d'athérosclérose. En effet, de par leur capacité à métaboliser le cholestérol (captation, stockage, efflux), à réguler l'inflammation et à phagocyter les cellules apoptotiques, ils exercent des fonctions pro et/ou anti-athèrogènes qui peuvent être modulées à des fins thérapeutiques. Dans cette perspective, nous avons évalué le pouvoir thérapeutique des " macrophages protégés de l'apoptose " sur la progression des lésions d'athérosclérose constituées. Nous avons démontré que l'augmentation de la survie des macrophages permet de ralentir la progression des lésions, de stabiliser les lésions et de diminuer la cholestérolémie. Ces effets athéro-protecteurs sont attribués à l'augmentation des cellules de Kupffer et des monocytes Ly-6Clow en partie par leur capacité à produire de l'apolipoprotéine E. Nous montrons également que les cellules de Kupffer participent à la clairance des lipoprotéines pro-athérogènes. L'augmentation du pool d'apoE ainsi que l'augmentation des cellules de Kupffer permettent de diminuer la cholestérolémie et ainsi de diminuer la progression des lésions. / Atherosclerosis represents a chronic pathophysiological process implicated in the majority of cardiovascular diseases. The development of atherosclerotic lesions is characterized by an accumulation of extra and intracellular lipids in the arterial wall at the origin of a strong inflammatory response involving macrophages.Macrophages are considered key actors in the development of atherosclerotic plaques. Indeed, because of their ability to metabolize cholesterol (capture, storage, efflux), to regulate inflammation and to phagocyte apoptotic cells, they exert pro and/or anti-atherogenic functions that may be modulated therapeutically. In this context, we evaluated the therapeutic potential of macrophages protected against apoptosis, on the progression of established atherosclerotic lesions.We have demonstrated that increased macrophage survival can slow down the progression of established lesions, stabilize lesion and reduce cholesterol levels. These athero-protective effects are attributed to the increase in Kupffer cells and Ly-6Clow monocytes partly due to their ability to produce apolipoprotein E. We also show that Kupffer cells are involved in the clearance of pro-atherogenic lipoproteins. The increase in ApoE pool and in Kupffer cells reduces cholesterol levels and thus lesion progression.

Artrite reumatóide é uma doença auto-imune que apresenta acentuado quadro inflamatório e proliferação celular o que, provavelmente, determina a alta prevalência de doenças cardiovasculares quando comparados a população mundial. A mortalidade e a morbidade conseqüentes das doenças cardiovasculares estão 2 vezes aumentadas em pacientes com artrite reumatóide e um dos principais fatores de risco relacionados ao desenvolvimento da aterosclerose é a dislipidemia. Esse importante fator de risco vem sendo associado à artrite reumatóide e as concentrações plasmáticas de lípides são constantemente avaliadas, já que se encontra bem estabelecido a relação entre dislipidemia e alta incidência de doença cardiovascular. No entanto, o verdadeiro impacto das alterações lipídicas na artrite reumatóide não é bem conhecido, já que os resultados de perfil lipídico são contraditórios. Alterações nas concentrações plasmáticas de lípides não necessariamente acompanham distúrbios no metabolismo das lipoproteínas plasmáticas. O objetivo do presente estudo foi avaliar aspectos do metabolismo da LDL e da HDL, em pacientes com artrite reumatóide. Nesse sentido, foi avaliada a cinética plasmática de uma nanoemulsão lipídica artificial com comportamento metabólico semelhante ao da LDL em 30 pacientes com artrite reumatóide divididos em 2 grupos de acordo com a atividade da doença, alta atividade (n=14) e remissão (n=16) e 30 indivíduos controle. A nanoemulsão marcada com éster de colesterol 14EC (EC-14C) e colesterol livre 3H (CL-3H) foi injetada endovenosamente após 12 horas de jejum. As amostras de sangue foram coletadas em tempos pré-determinados (5 min, 1, 2, 4, 6, 8 e 24 horas) após a injeção, para determinação das curvas de decaimento plasmático e da taxa fracional de remoção (TFR) dos lípides marcados, por análise compartimental. As TFR-EC-14C e TFR-CL-3H foram maiores no grupo AR quando comparado ao grupo controle (49%, p<0,05 e 44%, p<0,05, respectivamente), não havendo diferença entre os subgrupos de artrite reumatóide. No grupo artrite reumatóide e em seus subgrupos, as concentrações de HDL-C e apo E foram maiores quando comparados ao grupo controle (33%, p<0,0001 e 20%, p<0,01, respectivamente), enquanto os níveis de apo B foram menores na artrite reumatóide quando comparados ao grupo controle (16%, p<0,05). A transferência de colesterol esterificado radioativo da nanoemulsão para a HDL foi menor na artrite reumatóide, comparando-se com o grupo controle. A transferência dos outros lípides foi similar nos dois grupos. A HDL dos pacientes com artrite reumatóide foi menor do que a dos controles. Esses resultados podem contribuir com a melhor compreensão de possíveis mecanismos relacionados a uma maior incidência de doenças cardiovasculares em pacientes com artrite reumatóide / Mortality and morbidity, as a consequence of cardiovascular diseases, is twice as high in patients with rheumatoid arthritis than in the general worldwide population. This autoimmune disease has predominant inflammatory and cell proliferation background probably explains the high prevalence of cardiovascular disease. Dyslipidemias are important risk factors for cardiovascular disease. This study investigated the link between RA and plasma lipids as a predisposition to this high cardiovascular disease incidence. However, the impact of lipids on cardiovascular risk in rheumatoid arthritis is unclear. So much so, that lipid profiles in patients with rheumatoid arthritis in published studies is contradictory. The events of intravascular lipoprotein metabolism do not necessarily produce altered levels of plasma lipids. In an attempt to unravel novel dysfunctional mechanisms that could trigger pro-atherogenic processes beyond the concentration of the plasma lipids, plasma clearance of a lipidic nanoemulsion that resembles the LDL metabolic behavior were investigated in rheumatoid arthritis patients and compared to control subjects without the disease. 30 patients with rheumatoid arthritis divided into 2 groups according to disease activity, high activity (n=14) and remission (n=16), and 30 controls were studied. A nanoemulsion labeled with 14C-cholesteryl esther (14C-CE) and 3H-free cholesterol (3H-FC) were endovenously injected after which blood samples were collected at pre-determined periods (5 min, 1, 2, 4, 6, 8 and 24 hours), in order to determine the radioactivity of the plasma decay curves and calculate the fractional clearance rate (FCR) of the labeled lipids for compartmental analysis. In the rheumatoid arthritis group and subgroups the HDL-C and apo E concentration were higher when compared to control group (33%, p<0,0001 e 20%, p<0,01, respectively) while apo B concentration was lower (16%, p<0,05). The 14-CE-FCR and 3H-FC-FCR were greater in rheumatoid arthritis group and subgroups when compared to controls (49%, p<0,05 e 44%, p<0,05, respectively). There were no differences between the rheumatoid arthritis subgroups. Therefore, rheumatoid arthritis accelerates the LDL plasma removal, as indicated by a higher 14-CE-FCR and 3H-FC-FCR. The transfer of other lipids was also similar in both groups. The HDL of the rheumatoid arthritis patients was lower than that of the control group. These results could clarify possible mechanisms that can be related to a higher cardiovascular incidence in patients with rheumatoid arthritis

Low-density lipoproteins (LDL) are heterogeneous nanoparticles containing one copy of apolipoprotein B (~550 kDa) and thousands of lipids. LDL are the main plasma carriers of cholesterol and the major risk factor for atherosclerosis, the number one cause of death in the developed world. In atherosclerosis, LDL lipids are deposited in the arterial intima. Fusion of modified LDL in the arterial wall is an important underexplored triggering event in early atherosclerosis. Previous studies from our laboratory showed that thermal denaturation mimics LDL remodeling and fusion, and revealed the kinetic origin of LDL stability. Here, we report the first quantitative kinetic analysis of LDL stability. We show that LDL denaturation monitored by turbidity follows a sigmoidal time course that is unique among lipoproteins, suggesting that slow conformational changes in apoB precede lipoprotein fusion. High activation energy of LDL denaturation, Ea~100 kcal/mol, indicates disruption of extensive protein-protein and protein-lipid interactions involving large apoB domains. Next, we combined size-exclusion chromatography, gel electrophoresis and electron microscopy to show that dimerization is a common early step preceding LDL fusion. Monoclonal antibody binding studies indicated that α-helices in the N-terminal βα1 domain of apoB undergo conformational changes at early stages of LDL aggregation and fusion. Better understanding of these structural changes that prime LDL for fusion is important, as it may help control this pathogenic process before it occurs. We applied the kinetic approach to test how selected factors that are expected to contribute to LDL fusion in vivo affect the rate of LDL fusion and rupture in vitro. The results show that LDL fusion accelerates at pH<7, which may contribute to LDL retention in acidic atherosclerotic lesions. Fusion also accelerates upon increasing LDL concentration in near-physiologic range, which likely contributes to atherogenesis. Further, we showed that thermal stability of LDL decreases with increasing particle size, indicating that the pro-atherogenic properties of small dense LDL do not result from their enhanced fusion. Our work provides the first kinetic approach to measuring LDL stability and suggests that lipid-lowering therapies that reduce LDL concentration but increase the particle size may have opposite effects on LDL fusion.

No description available.

Magister Pharmaceuticae - MPharm / Cardiovascular diseases (CVDs) such as ischaemic heart diseases, heart failure and stroke remain a major cause of death globally. Various deep-rooted factors influence CVD development; these include but are not limited to elevated blood lipids, high blood pressure, obesity and diabetes. A considerable number of proteins are involved directly and indirectly in the transport, maintenance and elimination of plasma lipids, including high and low-density lipoprotein cholesterol (HDL-C and LDL-C). There are several mechanisms involved in the removal of LDL particles from systemic circulation. One such mechanism is associated with the gene that encodes proprotein convertase subtilisin/kexin type 9 (PCSK9), which has become an exciting therapeutic target for the reduction of residual risk of CVDs. Currently, statins are the mainstay treatment to reduce LDL-C, and a need exists to further develop more effective LDL-C-lowering drugs that might supplement statins. This study was aimed at contributing to the generation of knowledge regarding the effect of niacin in reducing LDL levels through PCSK9 interaction.

The leading cause of death among women is coronary heart disease (CHD), a multifactorial disease with polygenic heritability estimated at 50%. Polymorphisms in the family with sequence similarity 5, member C' (FAM5C) gene have been associated with myocardial infarction (MI), and one single-nucleotide polymorphism (SNP) has partially accounted for linkage in an acute coronary syndrome subset. The linkage peak on FAM5C corresponds directly with a quantitative trait locus for the inflammatory biomarker monocyte chemoattractant protein 1, as well as a linkage peak to metabolic syndrome (MetS). Metabolic syndrome increases the risk of developing CHD, and MI has been positively associated with elevated inflammatory biomarkers. This study was designed as a descriptive pilot gene association study. The purpose was to investigate the variability of the FAM5C SNP (rs10920501) in a cohort of women with documented CHD. It also examined the association between the variability of the FAM5C SNP (rs10920501), MetS, inflammatory markers, and the association with early onset CHD in the presence or absence of MI. A subset of 91 women was derived from an earlier study of women randomized to either a gender-tailored or traditional cardiac rehabilitation program. The results indicated the T allele of FAM5C SNP rs10920501 has a strong protective effect in women with a history of MI. Women with a history of MI and the heterozygous (AT) genotype had a mean age of onset of CHD at 62 years, compared to the homozygous wild type (AA) with a mean age of onset at 55 years, (F (3, 34) = 5.00, p < .01). No women in this study with the homozygous variant (TT) had an MI, further demonstrating the protective effective of the T allele. The genotype of FAM5C SNP rs10920501 explains approximately seven percent of the variability of age of onset of CHD in women who have had an MI, while holding body mass index (BMI) and smoking history constant. There was no significant relationship between FAM5C SNP (rs109320501) and MetS or any inflammatory biomarkers in this sample. In conclusion, FAM5C remains a gene of interest in a complex disease process.

Atherosclerosis, hardening and narrowing of the arteries, is the principal underlying cause of heart attacks, strokes, and peripheral vascular disease, which kills more than 600,000 Americans each year. High plasma levels of low-density lipoproteins (LDL) are linked to the formation of atherosclerotic plaques in arteries. LDL is the last metabolic product of very low-density lipoprotein (VLDL), which is secreted from the liver along with one molecule of apolipoprotein B (apoB). Current therapies to control levels of LDL include: cholesterol synthesis inhibitors or statins, low-fat diets and antisense oligonucleotides to reduce cholesterol levels. Recent studies recommend lower clinical levels of plasma LDL to maintain an individual’s health, especially of those who have already developed atheroscle- rotic plaques. However, existing therapies are often unable to achieve these aggressive limits. Furthermore, patients have shown various levels of intolerance to these treatments. In order to develop new, targeted drugs, that can control LDL levels with minimal side effects, it is imperative to understand, in detail, the process of apoB-containing lipoprotein formation. ApoB is one of the largest human proteins known (4563 residues) and previous attempts to solve the structure have been unsuccessful, mainly due to analyzing the protein as a whole or by large sections. To advance the field we will go by a different approach. I present here a construct that represents roughly 8% of the whole protein, apoB9-17 (residues 430 to 782). This section of the protein is believed to play a pivotal role in the assembly process of LDL. My hypothesis is that this construct will be well-behaved and suitable for structural and functional analysis. The study shows that apoB9-17 can be produced in considerable quantities from bacterial cells and can be purified by means of a 6-histidine tag with a good yield. Furthermore, circular dichroism analysis shows the construct contains the expected secondary structure at room temperature and is stable at a wide temperature range (50 to 70 ◦C) at low concentrations. The construct here described will be useful to test the effect of mutations such as the one found in patients with Familial hypobetalipoproteinemia (FHBL). Furthermore, this construct contains two regions believed to be of vital importance for LDL particle formation: the alpha-helical region (residues 430 to 570) is believed to associate with MTP at the initial stages of LDL formation and the c-sheet (residues 614 to 782), which may form part of the lipid recruiting process. Both essential aspects to ultimately develop therapies that can modulate VLDL particle formation.

Background: There is no study focusing on changes of coronary atherosclerosis during dual hypolipidemic therapy with statin and ezetimibe. Methods: 107 patients with stable angina were enrolled and the final analysis was performed in 89 patients. Randomization was 1:1 to the group A (atorvastatin 80mg and ezetimibe 10mg) and to the standard group S. Treatment period was 12 months. Results: Changes of percent atheroma volume (PAV) were -0,4% in group A and + 1,4% in group S, p=0,014. Combine atherosclerosis regression (increase of lumen volume together with decrease of PAV) was found more frequent in group A (40,5%) than the group S (14,9%), p=0,007. The target LDLc level < 2mmol/l, presence of at least four of five atherosclerotic risk factors, and decrease of VCAM level were independent predictors for plaque regression. There were no significant differences in plaque composition between the two groups over the duration of the study. However during analysis the two groups together, fibrous and fibro-fatty tissues decreased and dense calcification and necrotic core increased during follow-up. Conclusion: The dual hypolipidemic therapy starts atherosclerosis regression. Despite significant decrease of lipid levels the continuous plaque shift from fibro and fibro-fatty to necrotic with calcification...

Macrophage apoptosis is an important process in the pathophysiology of atherosclerosis. Oxidized low-density lipoproteins (OxLDL) are a major component of lesions and potently induce macrophage apoptosis. Cannabinoid receptor 2 (CB2), the predominant macrophage cannabinoid receptor, modulates several macrophage processes associated with ongoing atherosclerosis; however, the role of CB2 in macrophage apoptosis is unknown. To determine if CB2 influences a macrophage apoptotic pathway relevant to atherosclerosis, we examined the effect of CB2 deficiency on OxLDL-induced macrophage apoptosis. In situ terminal transferase-mediated dUTP nick end labeling (TUNEL) analysis of resident peritoneal macrophages detected significantly fewer apoptotic CB2-/- macrophages than CB2+/+ macrophages after incubation with OxLDL (27.9 ± 4.7% vs. 61.9 ± 8.5%, P < 0.001) or 7-ketocholesterol (7KC) (18.9 ± 10.5% vs. 54.1 ± 6.9%, P < 0.001), an oxysterol component of OxLDL. Caspase-3 activity; proteolytic conversion of procaspase-3; and cleavage of a caspase-3 substrate, PARP, were also diminished in 7KC-treated CB2-/-macrophages. Furthermore, the deactivation of the prosurvival kinase, Akt, in response to 7KC was impaired in CB2-/-macrophages. These results suggest that CB2 expression increases the susceptibility of macrophages to OxLDL-induced apoptosis, in part, by modulating the effect of oxysterols on the Akt survival pathway and that CB2 may influence atherosclerosis by modulating lesional macrophage apoptosis.

With the advent of more effective therapies for human immunodeficiency virus (HIV) infection, HIV-infected patients are living longer and cardiovascular disease is becoming more obvious in this population. Patients with HIV infection represent one of the most rapidly developing groups with cardiovascular disease globally. Cardiovascular disease complicating HIV infection is likely to contribute to burgeoning healthcare costs. Pericarditis, myocarditis, cardiomyopathy, atherosclerotic coronary vasculopathy, arterial aneurysms, pulmonary hypertension, and endocarditis occur with increased frequency in these patients. Pedcardial tamponade, dilated cardiomyopathy, endocarditis, and vasculopathy can lead to fatal outcomes in this population. The advent of cardiomyopathy heralds a very poor prognosis in patients infected with HIV. Coronary vasculopathy without obvious risk factors can lead to myocardial ischemia in young patients infected with the virus. MoreoVer, the protease inhibitors used to treat HIV infection induce a syndrome of lipodystrophy and dyslipidemia that may be associated with accelerated atherosclerosis as well as insulin resistance. All these factors contribute to increased cardiovascular morbidity and mortality in the HIV-infected population. HIV infection, opportunistic infections, secreted viral proteins such as gp120 (envelope protein) or Tat (transactivator of viral transcription), and cytokines elaborated during the course of HIV infection of the immune system all contribute to pathogenesis of these disorders. Further basic and clinical studies are required to understand the pathogenesis of cardiovascular complications and develop appropriate management strategies for these patients.