Introdução: A associação de uma estatina com ezetimiba é tão eficaz quanto altas doses da mesma estatina na redução do LDL-colesterol. Os efeitos que não dependem dessa redução são chamados de pleiotrópicos, entre os quais podemos citar: melhora da função endotelial, efeitos anti-oxidantes, efeitos anti- inflamatórios, entre outros. Objetivo: comparar a ação de dois esquemas de tratamento que obtêm reduções equivalentes de LDL-colesterol (sinvastatina 80 mg ao dia e associação sinvastatina 10mg/ezetimiba 10 mg ao dia), sobre os efeitos pleiotrópicos: inflamação, função endotelial e oxidação da LDL. Métodos: estudamos 23 pacientes randomizados e na forma de cross-over 2x2. A inflamação foi mensurada através da PCR-us, a função endotelial por meio de ultra-sonografia e a oxidação de LDL pelas dosagens de LDL eletronegativa (LDL-) e do anticorpo anti-LDL-. Resultados: A redução do LDL-colesterol foi similar nos dois grupos (45,27% no grupo sinvastatina/ezetimiba (p<0,001) e 49,05% no grupo sinvastatina (p<0,001), sem diferença entre os tratamentos (p=0,968)). Os dois grupos apresentaram melhora da função endotelial (3,61% no grupo sinvastatina/ezetimiba (p=0,003) e 5,08% no grupo sinvastatina (p<0,001), não houve diferença entre os tratamentos (p=0,291)). Houve melhora nos níveis da PCR-us (redução de -22,8% no grupo sinvastatina/ezetimiba (p=0,004) e de 29,69% no grupo sinvastatina (p=0,01), sem diferenças entre os tratamentos (p=0,380)). Não houve redução significativa da LDL-. Ocorreu aumento na concentração do anticorpo anti-LDL eletronegativa apenas no grupo sinvastatina (p=0,045). Conclusões: as duas formas de tratamento são eficazes na melhora da função endotelial e dos níveis de PCR-us. Somente com o uso da sinvastatina em alta dose houve aumento nos níveis de anticorpos anti-LDL-. / Introduction: The co-administration of a statin with ezetimibe is as effective as high doses of the same statin in the reduction of the LDL-cholesterol. The effects which don´t depend of this reduction are called pleiotropic effects, some among them can be cited: endothelial function improvement, antioxidative and anti-inflammatory effects. Objective: compare the effectiveness of these two different treatments that obtain equivalent reductions of LDLcholesterol (simvastatin 80 mg once a day and co-administration of simvastatin 10 mg once a day and ezetimibe 10 mg once a day), about pleiotropic effects: inflammation, endothelial function and LDL oxidation. Methods: we have studied 23 randomized patients in a 2x2 cross-over study. Inflammation was measured by high-sensitive C reactive protein, endothelial function by echocardiography and LDL oxidation by electronegative LDL and electronegative anti-LDL antibodies levels. Results: the LDL-cholesterol was similar between the two groups (45,27% reduction in the simvastatin/ezetimibe group (p<0,001) and 49,05% reduction in the simvastatin group (p<0,001); no difference between treatments was found (p=0,968). The two groups had improvement in endothelial function (3,61% in the simvastatin/ezetimibe group (p=0,003) and 5,08% in the simvastatin group (p<0,001)), no differences was found between the two groups (p=0,291). High-sensitive C reactive protein had a 22,8% reduction in the simvastatin/ezetimiba group (p=0,004) and 29,69% reduction in the simvastatin group (p=0,01), with no significative difference in any of the two treatments (p=0,380). There was no significative difference in LDL- levels. The anti-LDL- antibodies concentration was increased only in the simvastatin group (p=0,045). Conclusion: the two forms of treatments presented some similar pleiotropic effects - improvement in endothelial function and decreased hs-CRP levels. Only with a high simvastatim dose the anti-LDL- antibodies concentration was increased.

Introdução: A periodontite é uma doença inflamatória caracterizada clinicamente pela destruição dos tecidos de suporte dental. Apresenta etiologia multifatorial, sendo a principal causa o acúmulo de bactérias patogênicas na superfície dentária. A periodontite tem sido associada ao avanço da aterosclerose. Os indivíduos portadores da hipercolesterolemia familiar apresentam o desenvolvimento precoce da doença aterosclerótica devido à exposição crônica a níveis altos de colesterol total e LDL-colesterol. Não existem estudos que analisem a associação entre a infecção periodontal e aterosclerose subclínica nessa população. Objetivo: Este trabalho analisou a relação entre a aterosclerose, coronariana, carotídea e/ou aórtica, e a doença periodontal em indivíduos com hipercolesterolemia familiar e em controles presumidamente sem a doença. Métodos: Foram incluídos 82 indivíduos com diagnóstico de hipercolesterolemia familiar pelo critério do U.S. MEDPED e 31 indivíduos saudáveis como grupo controle. A calcificação arterial coronariana foi avaliada por tomografia computadorizada e a medida realizada pelo método de Agatston. O espessamento médio-intimal carotídeo e o diâmetro da artéria carótida comum direita foram determinados por ultrassom pulsátil tipo echotracking. A rigidez arterial foi medida por meio da velocidade das ondas de pulso. Todos os indivíduos responderam a um questionário estruturado e foram submetidos à avaliação periodontal. A sondagem periodontal dos dentes foi realizada em seis sítios por dente em cada paciente. Dados sobre inflamação gengival, presença de placa bacteriana, profundidade de sondagem, recessão gengival e perda de inserção clínica foram coletados. As variáveis contínuas foram comparadas pelo do teste t de Student não pareado ou teste de Mann-Whitney. Para as variáveis categóricas, foram aplicados os testes de qui-quadrado ou teste exato de Fisher. Resultados: Dos indivíduos do grupo controle, 32,3% apresentam quadro de periodontite grave, enquanto que no grupo caso, 64,1% apresentou esse quadro (p = 0,001). Nos grupos controle e caso, 19,4% contra 43,4% apresentam respectivamente mais que 15% de sítios com profundidade de sondagem > 4mm (p=0,02). Na análise intragrupo os indivíduos com periodontite avançada apresentaram valores mais elevados de espessura médio-intimal (p=0,04), velocidade de onda de pulso (p=0,04), proteína Creativa (p=0,02) e leucócitos séricos (p=0,04). Periodontite grave não foi associada com calcificação arterial coronariana. Conclusões: Periodontite grave, aterosclerose subclínica e elevados marcadores inflamatórios foram mais comumente observados nos indivíduos com hipercolesterolemia familiar / Introduction: Periodontitis is an inflammatory disease with consequent destruction of teeth supporting tissues. It has multifactorial etiology, and its main cause is accumulation of periodontal pathogens on the dental surface. Periodontitis has been associated with the advance of atherosclerosis. Familial hypercholesterolemia patients display premature development of atherosclerosis due to chronic exposure to high levels of total cholesterol and LDL-c. The association between subclinical atherosclerosis and periodontitis in this population has not been previously studied. Objective: This study analyzed the relation between coronary and/or carotid atherosclerosis and the periodontitis in patients with familial hypercholesterolemia. Methods: 82 individuals with familial hypercholesterolemia according to the U.S. MEDPED criteria (case group) and 31 healthy individuals (control group) were enrolled. Subclinical atherosclerosis was evaluated by three methods: coronary artery calcification, common carotid-artery intima and media thickness and the diameter of right common carotid artery, and arterial stiffness measured by aortic pulse wave velocity. All individuals answered a structured questionnaire and were submitted to a complete periodontal evaluation. Gingival inflammation, the presence of bacterial biofilm, probing depth, gingival recession and clinical attachment level were examined in six sites per tooth in each individual. Continuous variables were compared by Student t test or Mann-Whitney test. For categorical variables, Chisquare or Fisher exact test were applied. Results: In the control group, 32.3% showed advanced periodontitis, whereas in the case group, 64.1 % showed advanced periodontitis (p=0,001). In control and case groups, 19.4% versus 43.4% respectively showed more than 15 % of sites with probing depth > 4mm (p=0,02). Intra-group analysis revealed that both FH and healthy individuals showed positive association between advanced periodontitis and higher values of intima-media thickness (p=0.04), pulse wave velocity (p=0.04), C-reactive protein (p=0.02) and serum leukocytes (p=0.04). Advanced periodontitis was not associated with coronary artery calcification. Conclusions: Advanced periodontitis, subclinical atherosclerosis and elevated inflammatory markers were more frequently observed in FH individuals

We aimed to evaluate the endothelial function by combining RHI measurements and specific biochemical markers in the children with possible risk of premature manifestation of atherosclerosis and in the control group of healthy children. In all, 124 children (of which 106 patients divided into five groups according to diagnosis - type 1 diabetes mellitus, Crohn's disease, cystic fibrosis, familial hypercholesterolemia and acute lymphoblastic leukemia and 18 healthy controls) were enrolled in the study. During the study, we measured RHI using a new plethysmographic method and further evaluated biochemical markers of endothelial dysfunction (ADMA, E-selectin, hsCRP and VCAM) and lipidogram in individual groups of children. The primary objective of our study was the determination of RHI and biochemical parameters in healthy subjects and in selected risk groups of children (type 1 diabetes mellitus, Crohn's disease, cystic fibrosis, familial hypercholesterolemia and children after successful treatment of acute lymphoblastic leukemia). At the same time, we compared patients from individual groups with the control group. We found significantly elevated RHI values in groups of children with type 1 diabetes, Crohn's disease, cystic fibrosis, and children after successful treatment of acute lymphoblastic leukemia....

A hipercolesterolemia familiar (HF) é caracterizada por concentrações elevadas de LDL-c e alta prevalência de doença arterial coronária (DAC) precoce. Entretanto, o curso da DAC nos portadores de HF é variável e pode ser influenciado por outros fatores de risco. O objetivo foi avaliar parâmetros clínicos e nutricionais de adultos portadores de HF heterozigótica por estudo do tipo transversal. Coletou-se do prontuário dos pacientes resultados de exames laboratoriais, medidas de pressão arterial e diagnósticos clínicos. Verificou-se a concordância ou não entre as categorias de risco pelos escores de Framingham (ERF) e pelos critérios estabelecidos para os portadores de HF. Antecedentes pessoais e familiares para DAC, tabagismo, atividade física, consumo alimentar de gorduras, fibras e bebidas alcoólicas foram obtidos por questionário e medidas antropométricas foram aferidas. Foram comparados os grupos com e sem Síndrome Metabólica (SM) e os grupos com e sem DAC por análise univariada. Após, foram verificados os fatores determinantes para o desenvolvimento da DAC mediante modelo de regressão multivariada. Foram entrevistados 110 pacientes (68 mulheres) com média de idade de 48,9 ± 16,2 anos. A presença de história familiar de DAC precoce foi relatada por 67 (61,5%) pacientes. A hipertensão foi encontrada em 59 (53,6%), SM em 38 (34,9%), DAC em 30 (27,3%), HDL-c baixo em 28 (25,5%), diabete melito em 17 (15,5%), 25 (22,7%) eram ex-fumantes e 12 (10,9%) tabagistas. Com a comparação das categorias de risco observou-se discrepância em 77,5% dos casos entre os ERF e os critérios estabelecidos para a população de HF. Quanto ao estado nutricional, 47 (42,7%) eram pré-obesos e 61 (55,4%) com circunferência da cintura alterada. O consumo de gorduras, fibras e bebidas alcoólicas foi considerado adequado. Encontrou-se grande número de sedentários (77%). O grupo dos pacientes com SM tinha idade mais avançada (55 vs 46 anos; p = 0,002), maior número de mulheres (76,3%; p = 0,02) e portadores de DAC (42,1%; p = 0,013). O grupo dos coronarianos tinha idade mais avançada (55 vs 47 anos; p = 0,004), mais pacientes do sexo masculino (60%; p = 0,004), maior presença de hipertensos (90%; p = 0,001), exfumantes (40%; p = 0,008), com SM (53,3%; p = 0,013), HDL-c baixo (53,3%; p = 0,001) e antecedente de infarto agudo do miocárdio (IAM) em irmãos (50%; p = 0,012). As medidas antropométricas, o consumo alimentar e a atividade física não foram diferentes entre os grupos. Após análise de regressão multivariada os fatores de risco determinantes para o desenvolvimento da DAC foram HDL-c baixo (OR 8,4; IC 95% 2,7-27,6), sexo masculino (OR 7,3; IC 95% 2,1-24,7), história de IAM em irmãos (OR 3,4; IC 95% 1,1-10,5) e idade avançada (OR 1,06; IC 95% 1,02-1,1). Em nossa população, HDL-c baixo, sexo masculino, história de IAM em irmãos e idade foram fatores independentes para o desenvolvimento da DAC. / Familial hypercholesterolaemia (FH) is characterized by raised concentrations of LDL-c and high prevalence of premature coronary artery disease (CAD). However, the course of the CAD in the FH is variable and can be influenced by other risk factors. The aim of the study was to assess clinical and nutritional parameters in adults with heterozigous FH by a cross sectional study. Laboratory exams, blood pressure measurement and clinical diagnosis were collected. Agreement or not between the categories of risk by Framingham scores and for established criteria for the FH subjects was verified. Personal and familial history for CAD, smoken habit, physical activity, fats, fibers and alcohol consumption were assessed by questionnaire and anthropometric measurement were verified. The groups with and without Metabolic Syndrome (MS) and groups with and without CAD were compared by univariated analysis. After, multivaried analysis (MVA) was used to assess the significance of differences in risk factors. The sample was composed by 110 patients (68 women) with average of age of 48.9 ± 16.2 years. The presence of familial history of premature CAD was detected in 67 (61.5%)subjects. Hypertension was found in 59 (53.6%), MS in 38 (34.9%), CAD in 30 (27.3%), low HDL-c in 28 (25.5%), diabetes in 17 (15.5%), 25 (22,7%) and 12 (10,9%) were respectively former and current smokers. In the comparison of the risk categories discrepancy was observed in 77.5% of the cases between the Framingham scores and the established criteria for the FH population. Analyzing the nutritional profile, 47 (42.7%) were overweight and 61 (55.4%) had increased waist circumference. The consumption of fats, fibers and alcohol were considered satisfactory. A great number of sedentary subjects was found (77%). The patients with MS were older (55 vs. 46 years; p = 0.002), had a greater number of women (76.3%; p = 0.02) and CAD (42.1%; p = 0.013). CAD subjects were older (55 vs. 47 years; p = 0.004), had a higher prevalence of males (60%; p = 0.004), hypertension (90%; p = 0.001), former smokers(40%; p = 0.008), MS (53.3%; p = 0.013), low HDL-c (53.3%; p = 0.001) and history of myocardial infarction in brothers (50%; p = 0.012). There were no differences between the groups regarding anthropometric measurements, consumption of fats, fiber and alcohol and physical activity. After MVA, independent risk factors for CAD were low HDL-c (OR 8.4; CI 95% 2.7-27.6), male gender (OR 7.3; CI 95% 2.1-24.7), history of myocardial infarction in brothers (OR 3.4; CI 95% 1.1-10.5) and advanced age (OR 1.06; CI 95% 1.02-1.1). In our population, low HDL-c, male gender, history of myocardial infarction in brothers and age were independently associated with the risk of CAD.

O objetivo deste estudo foi avaliar o efeito da sinvastatina, isolada e associada ao &#945;-tocoferol e à L-arginina, sobre os inibidores endógenos da óxido nítrico sintase, os metabólitos do óxido nítrico e tióis, em pacientes hipercolesterolêmicos. Analisou-se um grupo de 16 pacientes hipercolesterolêmicos que seguiram o seguinte protocolo: período de washout (sem medicação), 1 mês; sinvastatina (20mg/dia), 2 meses; sinvastatina (20mg/dia) + &#945;-tocoferol (400U/dia), 2 meses; sinvastatina (20mg/dia, washout), 1 mês; sinvastatina (20mg/dia) + L-arginina (7g/dia), 2 meses. A sinvastatina reduziu significativamente as concentrações do colesterol total e LDL-colesterol e a razão LDL-colesterol/HDL-colesterol. O tratamento com sinvastatina, isolada e associada ao &#945;-tocoferol, promoveu diminuição nas concentrações de S-nitrosotióis. A L-arginina associada à sinvastatina, aumentou os níveis de colesterol total quando comparada com a sinvastatina isoladamente. As concentrações plasmáticas de &#945;-tocoferol e L-arginina não aumentaram em decorrência da suplementação, devido à grande dispersão dos dados obtidos, embora as medianas das concentrações plasmáticas de Larginina e &#945;-tocoferol tenham sido mais elevadas após as suplementações. O tratamento com sinvastatina, isolada ou associada à L-arginina e ao &#945;-tocoferol, não alterou as concentrações dos inibidores endógenos da óxido nítrico sintase (ADMA e SDMA), dos metabólitos do óxido nítrico, da nitrotirosina total e dos tióis analisados. / The aim of this study was to evaluate the effect of sinvastatin, isolated and associated to &#945;-tocopherol and to L-arginine, on the endogenous inhibitors of nitric oxide synthase, on nitric oxide metabolytes and thiols, in hypercholesterolemic patients. A group of 16 hypercholesterolemic patients were analysed, acconting to the protocol: a washout period (without medication) of 1 month, sinvastatin (20 mg/day) for 2 months; sinvastatin (20 mg/day) + &#945;-tocopherol (400U/day) for 2 months; sinvastatin (20 mg/day) for 1 months (washout period), sinvastatin (20 mg/day) + L-arginine (7g/day) for 2 months. Sinvastatin significantly reduced the concentrations of total cholesterol and LDL-cholesterol, as well as the LDL-cholesterol/HDLcholesterol ratio. The treatment with sinvastatina, alone and associate to &#945;-tocoferol, resulted in a reduction of RSNO concentration. The L-arginine associated with sinvastatin, increase the level of total cholesterol as compared with simvastatin alone. The plasma concentrations of a-tocopherol and Larginine did not increase following supplementation due to the large dispersion of the data obtained, even though the median plasma concentrations of L-arginine and a-tocopherol were elevated after supplementation. Treatment with simvastatin, alone or associated to L-arginine and a-tocopherol did not alter the concentrations of the endogenous inhibitors of nitric oxide synthase (ADMA and SDMA), or that of nitric oxide metabolytes, total nitrotyrosine or the thiols analysed.

Como demonstrado em estudos prévios, quando injetada em indivíduos, a microemulsão lipídica rica em colesterol sem proteína (LDE) que mimetiza a composição da LDL adquire apoE no plasma e é captada por receptores de LDL. No presente estudo, a LDE marcada com colesterol-H3(CL) e oleato de colesterol-C14(OC) foi injetada em 20 pacientes com doença arterial coronária antes da cirurgia de revascularização miocárdica. Fragmentos de aorta, artéria radial, artéria torácica interna, veia safena e pericárdio descartados durante a cirurgia foram coletados e analisados para radioatividade juntos com amostras seriadas de plasma. A contagem radioativa de LDE-OC foi maior do que a de LDE-CL em todas amostras de plasma coletadas durante 24h, entretanto a captação de LDE-CL foi expressivamente maior do que a do OC em todos os fragmentos. A captação de LDE-CL pela aorta foi cinco vezes maior do que a de LDE-OC (p=0,0379), quatro vezes maior na artéria torácica interna (p=0,033), dez vezes maior na veia safena (p=0,006) e quatro vezes maior no pericárdio (p=0,010). Apenas na artéria radial a captação não obteve significância estatística (p=0,053). Os estudos in vitro de captação celular, bloqueio e das marcações imuno-histoquímicas confirmaram os achados in vivo. Concluindo, a expressiva captação vascular do CL comparada com à do OC sugere que o CL dissocia-se a partir das partículas da microemulsão e precipita-se nos vasos. Considerando a LDE como um modelo de microemulsão artificial para a LDL, os resultados sugerem que este tipo de deposição do CL na parede vascular pode constituir um novo mecanismo para a aterogênese. / As shown in previous studies, when injected into subjects, a protein-free cholesterol-rich microemulsion (LDE) that mimics LDL composition acquires apoE in the plasma and is taken-up by LDL receptors. In the current study, LDE labeled with H3-Cholesterol (FC) and C14-Cholesteryl Oleate(CO) was injected into 20 coronary artery disease patients 24h before myocardial revascularization surgery. Fragments of aortic, radial, internal thoracic arteries, safenous vein and pericardium discarded during surgery were collected and analyzed for radioactivity together with serial plasma samples. The radioactive counting of LDE-CO was greater than that of LDE-FC in all the plasma samples collected over 24h, but the uptake of LDE-FC was markedly greater than that of CO in all fragments. The uptake of LDE-FC by aorta was 5-fold greater than that of LDE-CO (p=0,0379), 4-fold greater in the internal thoracic artery (p=0,033), 10-fold greater in safenous vein (p=0,006) and 4-fold greater in pericardium (p=0,010). Only in the radial artery the uptake didn\'t attains statistical significance (p=0,053). The in vitro studies of cell uptake, blocking and immunohistochemistry marks confirm the in vivo finds. In conclusion, the remarkably greater vessel tissue uptake of FC compared with CO suggests that FC dissociate from the microemulsion particles and precipitate in the vessels. Considering LDE as an artificial microemulsion model for LDL, the results suggests that this type of FC deposition in the arterial wall, might constitute a novel atherogenic mechanism.

La transplantation d’hépatocytes est un procédé séduisant pour remplacer les cellules déficientes dans un foie anatomiquement normal. Dans les maladies métaboliques héréditaires hépatiques (MMHH), la thérapie cellulaire présente un potentiel espoir thérapeutique. Le remplacement d'un pourcentage restreint (5-10%) d’hépatocytes déficients par des hépatocytes normaux pourrait rétablir durablement la fonction métabolique. Les résultats des essais cliniques de transplantation d'hépatocytes génétiquement modifiés ou non sont moins concluants, montrent une prise de greffe insuffisante et, dans la plupart des études, un effet thérapeutique transitoire. L’efficacité limitée de la transplantation d’hépatocytes isolés dans le traitement des MMHH semble en partie liée au faible pourcentage de la masse hépatocytaire reconstituée par les hépatocytes définitivement greffés et fonctionnels. De nombreux modèles animaux ont été développés pour étudier les facteurs pouvant augmenter le nombre et le pourcentage d’hépatocytes transplantés et greffés. Cependant, la majorité de ces modèles ne sont pas transposables en clinique car ils présentent des risques importants ou mal évalués pour les patients. Les principaux objectifs de ce travail ont été d’étudier des moyens peu invasifs pour induire une régénération hépatique et une prise de greffe hépatocytaire significatives dans le but de développer une nouvelle approche de transplantation d’hépatocytes génétiquement modifiés ex vivo pour le traitement de l’hypercholestérolémie familiale. L’effet d’une embolisation portale partielle (EPP) réversible sur la prolifération hépatocytaire et la régénération hépatique a été évalué chez le macaque. A la différence de l’EPP par un produit non résorbable, il ne s’agit pas d’une approche potentiellement délétère à long terme. Une obstruction veineuse plus complète a été provoquée en utilisant le Curaspon®, une gélatine biodégradable, en forme de poudre. Nous avons démontré pour la première fois dans la littérature l’efficacité d’une EPP réversible à induire une importante prolifération hépatocytaire et régénération hépatique. Nos données suggèrent qu’une occlusion portale initiale et temporaire est suffisante pour déclencher les mécanismes responsables d’une régénération hépatique dans le foie non-embolisé. L’utilisation du Curaspon® en poudre peut être considérée comme la forme la plus évoluée d’EPP : très distale, résorbable, qui dure suffisamment pour induire l’hypertrophie hépatique. Cette technique pourrait être indiquée dans des situations cliniques nécessitant une régénération hépatique de courte durée (ex. le traitement des cancers du foie en plusieurs étapes) ou dans des cas qui ne nécessitent pas une résection hépatique, comme la transplantation d’hépatocytes pour le traitement de MMHH. Ces résultats nous ont permis d’évaluer cette approche dans notre protocole préclinique de thérapie génique pour le traitement de l’hypercholestérolémie familiale chez le primate, par autotransplantation d’hépatocytes génétiquement modifiés ex vivo par un vecteur lentiviral. Nous avons démontré que l’EPP réversible induit une régénération hépatique du foie non-embolisé et améliore notablement les résultats de la transplantation d’hépatocytes isolés génétiquement modifiés exprimant la GFP. Seize semaines après la transplantation, les hépatocytes transduits et greffés exprimaient le transgène contrôlé par le promoteur apo-AII humain. Notre protocole a montré pour la première fois chez un gros animal que l’EPP par un produit résorbable entraine avec des conditions de sécurité optimales une repopulation hépatique importante par des hépatocytes transduits par un vecteur lentiviral, et ceci même à distance de la transplantation hépatocytaire. Les résultats encourageants de ces travaux nous ont ouvert la voie pour avancer sur notre projet préclinique et envisager la réalisation d’une étude clinique de phase I/II pour le traitement de l’hypercholestérolémie familiale. / Hepatocyte transplantation is an attractive process for replacing deficient cells in an anatomically normal liver. In metabolic liver diseases, cell therapy could be an interesting alternative to orthotopic liver transplantation. The replacement of a small percentage (5-10%) of deficient hepatocytes by normal hepatocytes could restore the metabolic defect at a long term. Data from clinical studies of hepatocyte autotransplantation or allotransplantation, genetically modified or not, provided poor results, insufficient cell engraftment in the liver parenchyma and, in the majority of cases, a transient therapeutic effect. The limited efficacy of hepatocyte transplantation in metabolic liver diseases is mainly due to the poor percentage of engrafted and finally functional hepatocytes. Numerous animal models have been developed in order to study the factors that could increase the number and the percentage of transplanted and engrafted hepatocytes. However, the majority of these models cannot be used in patients since they present important risks for them. The aim of this work was to evaluate less invasive procedures for inducing liver regeneration and significant hepatocyte engraftment in order to develop a new approach of transplantation of ex vivo genetically modified hepatocytes for the treatment of familial hypercholesterolemia. The effect of reversible portal vein embolization (PVE) on liver regeneration and hepatocyte proleferation was evaluated in monkeys. In contrast to PVE by a permanent embolizing agent, reversible PVE has not a long term deleterious effect on embolized liver. A more complete venous occlusion was obtained by using the powdered form of an absorbable gelatin sponge (Curaspon®). We showed for the first time in the literature the safe and successful use of reversible PVE for inducing significant hepatocyte proliferation and liver regeneration. Our data support that an initial occlusion of the portal branch, even if not permanent, is sufficient to start the mechanisms of liver regeneration in the contralateral lobe. Embolization with Curaspon® powder could be considered to be the ultimate form of embolization: very distal, reversible and lasting sufficiently in order to induce substantial liver hypertrophy. Our findings suggest that this method could reliably be used for clinical purposes, particularly in situations in which short-term regeneration is required (i.e. multi-step management of hepatic malignancies) or in cases where resection of the liver is not finally necessary, such as in hepatocyte transplantation for the treatment of metabolic liver diseases. These promising results on reversible PVE allowed us to evaluate this approach in our preclinical study of gene therapy for the treatment of familial hypercholesterolemia in macaques. Our protocol consisted of an autotransplantation of ex vivo genetically modified hepatocytes by a lentiviral vector. We showed that reversible PVE induces liver regeneration of the non-embolized liver segments and improves considerably hepatocyte transplantation of genetically modified cells expressing Green Fluorescent Protein (GFP). Sixteen weeks after transplantation, transduced engrafted hepatocytes expressed the transgene, which was under control of the human apo-AII promoter. Our protocol showed for the first time in a big animal that PVE by an absorbable agent leads safely to an important and long-term repopulation of the liver by lentivirally transduced hepatocytes. The extremely encouraging results of this work opened our way advancing in our preclinical study and preparing a phase I/II clinical trial for the treatment of familial hypercholesterolemia based on our protocol of autotransplantation of ex vivo genetically modified hepatocytes by a lentiviral vector.

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Les maladies cardiovasculaires (MCV) demeurent au tournant de ce siècle la principale cause de mortalité dans le monde. Parmi les facteurs de risque, l’hypercholestérolémie et l’obésité abdominale sont directement liées au développement précoce de l’athérosclérose. L’hypercholestérolémie familiale, communément associée à une déficience des récepteurs des lipoprotéines de basse densité (LDLR), est connue comme cause de maladie précoce d’athérosclérose et de calcification aortique chez l’humain. La subtilisine convertase proprotéine/kexine du type 9 (PCSK9), membre de la famille des proprotéines convertases, est trouvée indirectement associée aux MCV par son implication dans la dégradation du LDLR. Chez l'humain, des mutations du gène PCSK9 conduisent soit à une hypercholestérolémie familiale, soit à une hypocholestérolémie, selon que la mutation entraîne un gain ou une perte de fonction, respectivement. Il demeure incertain si les individus porteurs de mutations causant un gain de fonction de la PCSK9 développeront une calcification aortique ou si des mutations entraînant une perte de fonction provoqueront une obésité abdominale. Dans cette étude, nous avons examiné : 1) l’effet d’une surexpression de PCSK9 dans le foie de souris sur la calcification aortique ; 2) les conséquences d’une déficience en PCSK9 (Pcsk9 KO), mimant une inhibition pharmacologique, sur le tissu graisseux. Nous avons utilisé un modèle de souris transgénique (Tg) surexprimant le cDNA de PCSK9 de souris dans les hépatocytes de souris et démontrons par tomographie calculée qu’une calcification survient de façon moins étendue chez les souris PCSK9 Tg que chez les souris déficientes en LDLR. Alors que le PCSK9 Tg et la déficience en LDLR causaient tous deux une hypercholestérolémie familiale, les niveaux seuls de cholestérol circulant ne parvenaient pas à prédire le degré de calcification aortique. Dans une seconde étude, nous utilisions des souris génétiquement manipulées dépourvues de PSCK9 et démontrons que l’accumulation de graisses viscérales (adipogenèse) apparaît régulée par la PCSK9 circulante. Ainsi, en l’absence de PCSK9, l’adipogenèse viscérale augmente vraisemblablement par régulation post-traductionnelle des récepteurs à lipoprotéines de très basse densité (VLDLR) dans le tissu adipeux. Ces deux modèles mettent en évidence un équilibre dynamique de la PCSK9 dans des voies métaboliques différentes, réalisant un élément clé dans la santé cardiovasculaire. Par conséquent, les essais d’investigations et d’altérations biologiques de la PCSK9 devraient être pris en compte dans un modèle animal valide utilisant une méthode sensible et en portant une attention prudente aux effets secondaires de toute intervention. / Cardiovascular disease (CVD) is the leading cause of death in the 21st century. Among risk factors, hypercholesterolemia and abdominal obesity are directly linked to premature development of atherosclerosis. Familial hypercholesterolemia, commonly due to low-density lipoprotein receptor (LDLR) deficiency, is known to cause premature atherosclerosis and aortic calcification in humans. Proprotein convertase subtilisin/kexin 9 (PCSK9), a member of the proprotein convertase family, is indirectly associated with CVD through enhanced LDLR degradation. Mutations in the human PCSK9 gene lead to either familial hypercholesterolemia or hypocholesterolemia, depending on whether the mutation causes a gain or a loss of function, respectively. It is uncertain if individuals carrying mutations causing a gain-of-function of PCSK9 will develop aortic calcification or whether loss-of-function mutations will lead to abdominal obesity. In this thesis, we investigated: 1) the effect of PCSK9 overexpression on aortic calcification; 2) the consequences of PSCK9 deficiency, mimicking pharmacological inhibition of PCSK9 on fat tissue. We employed a transgenic (Tg) mouse model overexpressing mouse PCSK9 and illustrated by micro-computerized tomography that calcification occurs to a lesser extent in PCSK9 Tg mice than in LDLR-deficient mice. While both PCSK9 Tg and LDLR deficiency caused familial hypercholesterolemia, circulating cholesterol levels alone could not dictate the degree of aortic calcification. In another study, we used genetically modified mice lacking PCSK9 and demonstrated that visceral fat accumulation (adipogenesis) is regulated by circulating PCSK9. Thus in the absence of PCSK9, visceral adipogenesis increases likely via post-translational regulation of very-low-density lipoproteins receptors (VLDLR) in the adipose tissue. In conclusion, these two studies highlight the dynamic balance of PCSK9 in different metabolic pathways, making it a key element in cardiovascular health. Consequently, attempts to survey and/or alter PCSK9 biology should be performed in a valid animal model using sensitive methods and with careful attention to side effects of any given intervention.

La stéatose hépatique et la détérioration du profil lipidique plasmatique sont des pathologies métaboliques favorisées par la carence œstrogénique post-ménopausique. Cependant les mécanismes à la base de ces pathologies n’ont été que très peu étudiés. Le but de cette thèse a été d’investiguer les mécanismes moléculaires possibles à l’origine de l’hypercholestérolémie et de l’accumulation des lipides (triglycérides : TG et cholestérol) dans le foie en utilisant un modèle animal de la ménopause, la rate Sprague Dawley ovariectomisée (Ovx). Nous avons également examiné si le changement des habitudes de vie comme la pratique de l’exercice physique pouvait prévenir ou corriger les modifications induites par l’Ovx. Enfin, rosuvastatine (statine) a été utilisée comme thérapie pharmacologique de l’hypercholestérolémie dans le but de comprendre son effet au niveau moléculaire chez la rate Ovx. L’objectif de la première étude était de déterminer comment l’Ovx peut affecter les niveaux de TG et de cholestérol dans le foie des rates nourries avec une diète riche en lipides (HF : 42% gras). Les rates ont été soumises à la diète HF ou normale pendant 6 semaines avant d’être Ovx ou Sham (ovariectomie simulée), puis maintenues aux mêmes conditions diététiques pour 6 autres semaines. L’Ovx a provoqué une accumulation de TG dans le foie, mais pas la diète HF seule. Cependant, lorsque l’Ovx était combinée à la diète HF, l’accumulation des TG était beaucoup plus importante comparé à ce qui était observé chez les rates Ovx soumises à la diète normale. L’expression génique (ARNm) de CPT1 (Carnitine palmitoyltransferase 1), PGC1α (Peroxisome proliferator-activated receptor gamma, coactivator 1) et PPARα (Peroxysome proliferetor activated receptor alpha) intervenant dans l’oxydation des acides gras dans le foie était augmentée par la diète HF (p ˂ 0.001; p ˂ 0.01; p ˂ 0.05 respectivement) ; mais atténuée (p ˂ 0.05; p ˂ 0.05; p ˂ 0.07 respectivement) lorsque les rates ont été Ovx, favorisant ainsi l’accumulation des TG dans le foie. La combinaison de la diète HF à l’Ovx a également provoqué une hypercholestérolémie et une accumulation de cholestérol dans le foie malgré la diminution de l’expression de la HMGCoA-r (3-hydroxy-3-methylglutaryl-CoA reductase), enzyme clé de la synthèse du cholestérol. Ceci était associé à l’inhibition de l’expression génique de CYP7a1 (Cytochrome P450, family 7, subfamily a, polypeptide 1), suggérant une diminution de la synthèse des acides biliaires. Ayant constaté dans la première étude que l’Ovx élevait les niveaux de cholestérol hépatique et plasmatique, nous nous sommes fixés comme objectif dans la deuxième étude d’évaluer les effets de l’Ovx sur l’expression génique des transporteurs et enzymes responsables du métabolisme du cholestérol et des acides biliaires dans le foie et l’intestin, et de vérifier si l’exercice sur tapis roulant pouvait prévenir ou corriger les changements causés par l’Ovx. L’hypercholestérolémie constatée chez les rates Ovx comparativement aux Sham était accompagnée de la diminution de l’expression génique des récepteurs des LDL (R-LDL), des résidus de lipoprotéines (LRP1), de SREBP-2 (Sterol regulatory element binding protein 2) et de PCSK9 (Proprotein convertase subtilisin/kexin type 9) dans le foie, suggérant une défaillance dans la clairance des lipoprotéines plasmatiques. L’Ovx a aussi inhibé l’expression génique de la MTP (Microsomal triglyceride transfer protein) et stimulé celle de SR-B1 (Scavenger receptor class B, member 1); mais aucun changement n’a été observé avec CYP7a1. Ces changements moléculaires pourraient par conséquent favoriser l’accumulation de cholestérol dans le foie. L’exercice physique n’a pas corrigé les modifications causées par l’Ovx sur l’expression génique de ces molécules au niveau hépatique à l’exception de SREBP-2. Par contre, au niveau intestinal (iléum), l’exercice sur tapis roulant a inhibé l’expression génique des marqueurs moléculaires intervenant dans l’absorption des acides biliaires (OSTα/β, FXR, RXRα, Fgf15) et du cholestérol (LXRα, NCP1L1) au niveau de l’iléum chez les rates Sham entraînées. Ces adaptations pourraient prévenir le développement de l’hypercholestérolémie protégeant en partie contre la survenue de l’athérosclérose. Au vue des effets délétères (hypercholestérolémie et diminution de l’expression du R-LDL, PCSK9, LRP1, SREBP-2 et HMGCOA-r dans le foie) causés par l’Ovx sur le métabolisme du cholestérol constatés dans l’étude 2, la 3ième étude a été conçue pour évaluer l’efficacité de rosuvastatine (Ros) sur l’expression génique de ces marqueurs moléculaires chez les rates Ovx sédentaires ou soumises à l’entraînement volontaire. Ros a été administrée aux rates Ovx pendant 21 jours par voie sous-cutanée à la dose de 5mg/kg/j à partir de la 9ième semaine après l’Ovx. Ros n’a pas diminué la concentration plasmatique de LDL-C et de TC chez les rates Ovx. Par contre, Ros a stimulé (P ˂ 0.05) l’expression génique de PCSK9, SREBP-2, LRP1, HMGCoA-r et ACAT2 (Acyl-CoA cholesterol acyltransferase) mais pas significativement (P = 0.3) celle du R-LDL dans le foie des rates Ovx sédentaires et entraînées. Ros n’a pas réduit la concentration plasmatique de LDL-C probablement à cause de l’induction plus importante de PCSK9 par rapport au R-LDL. Cependant, la stimulation de LRP1 par Ros protège partiellement contre la survenue des maladies cardiovasculaires. En conclusion, les études de cette thèse indiquent que la baisse du niveau des œstrogènes entraîne des changements radicaux du métabolisme hépatique des TG et du cholestérol provoqués par des altérations de l’expression des gènes clés des voies métaboliques associées. / Hepatic steatosis and plasma lipid profile deterioration are metabolic diseases favored by post-menopausal estrogen deficiency. However, mechanisms underlying these diseases have not been systematically adressed. The aim of this thesis was to investigate molecular mechanisms causing hypercholesterolemia and lipids (triglycerides: TG and cholesterol) accumulation in the liver using animal model of menopause, the ovariectomized (Ovx) Sprague Dawley rat. We also examined whether lifestyle modifications such as physical activity can prevent or correct changes induced by Ovx. Finally, rosuvastatin (statine) was used as a pharmacological therapy of hypercholesterolemia in order to understand its effect at the molecular level in Ovx rats. The first study was designed to determine how the Ovx may affect levels of TG and cholesterol in the liver of rats fed a high-fat diet (HF: 42% fat). Rats were submitted to a HF or a normal diet for 6 weeks prior to Ovx or being sham operated, and then kept on the same diets for another 6 weeks. The Ovx increased liver TG content, but not the HF diet alone. However, the combination of Ovx and HF diet resulted in a greater liver TG accumulation than that observed in Ovx submitted to normal diet. The mRNA levels of CPT-1, PGC1 and PPARα involved in liver lipid oxidation significantly increased in rats fed the HF diet (p ˂ 0.001; p ˂ 0.01; p ˂ 0.05 respectively); but this increase was substantially less if HF fed rats were Ovx (p ˂ 0.05; p ˂ 0.05; p ˂ 0.07 respectively), thus favouring TG accumulation in the liver. The combination of HF diet and Ovx also induced hypercholesterolemia and an increase in liver total cholesterol content, in spite of the reduction of liver HMGCoA-r gene expression, the key enzyme for cholesterol synthesis. This was also associated with a decrease of liver CYP7a1 gene expression, suggesting a reduction in bile acids synthesis. Having found in the first study that the Ovx increases liver and plasma cholesterol levels, we aimed in the second study at determining the effects of Ovx on gene expression of hepatic and intestinal transporters and enzymes involved in cholesterol and bile acids metabolism; and to verify whether treadmill exercise could prevent or correct changes induced by Ovx. The Ovx resulted in hypercholesterolemia associated with a reduction in gene expression of hepatic low-density lipoprotein receptor (LDL-R), lipoprotein remnants receptor (LRP1), SREBP-2 and PCSK9, suggesting a failure in the clearance of plasma lipoproteins particles. The Ovx also inhibited the expression of MTP and stimulated that of SR-B1 in the liver, but no change was observed with CYP7a1. These molecular changes might, therefore, favor cholesterol accumulation in the liver. Exercise training did not correct the deleterious effects caused by Ovx on gene expression of these molecular markers in the liver with the exception of SREBP-2. However, in the intestine (ileum) treadmill exercise reduced gene expression of molecular markers involved in the absorption of bile acids (OSTα/β, FXR, RXRα, Fgf15) and cholesterol (LXRα, NCP1L1) in Sham trained rats compared to sedentary rats. This could prevent the development of cholestasis and hypercholesterolemia protecting partially against the onset of atherosclerosis. In view of the deleterious effects (hypercholesterolemia and decreased in gene expression of LDL-R, PCSK9, LRP1, SREBP-2 and HMGCoA-r in the liver) caused by Ovx on cholesterol metabolism observed in the second study, the 3rd study was designed to test the effect of rosuvastatin (Ros) on gene expression of these molecular markers in Ovx sedentary rats or in Ovx rats submitted to voluntary training. Ros was injected to Ovx rats subcutaneously at dose of 5mg/kg/day during 21 days from the ninth week after ovariectomy. Ros failed to decrease plasma LDL-C and TC in Ovx rats. In contrast, Ros increased (P ˂ 0.05) PCSK9, SREBP-2, LRP1, HMGCoA-r and ACAT2 but not significantly (P ˂ 0.3) LDL-R mRNA in the Ovx sedentary and trained rat liver. Ros failed to decrease plasma LDL-C in Ovx rats probably because of a stronger induction of PCSK9 than LDL-R gene expression. However by increasing LRP1 expression, Ros could decrease circulating lipoprotein remnants and, therefore, protects partially against the onset of cardiovascular diseases. In conclusion, the studies of this thesis indicate that the decrease of ovarian estrogen levels causes radical changes in hepatic TG and cholesterol metabolism caused by alterations in the expression of key genes associated with metabolic pathways.