Le syndrome d'Ehlers-Danlos (SEDv) est une maladie artérielle génétique autosomique dominante, affectant le collagène de type III au sein de la matrice extracellulaire de la paroi artérielle notamment. Les patients atteints de SEDv ont une prédisposition aux ruptures artérielles, digestives et utérines qui font toute la sévérité de cette maladie. Les mutations du gène COL3A1 codant pour le collagène de type III sont le plus souvent des mutations hétérozygotes faux-sens, responsables de la substitution d'une glycine par un autre acide aminé, affectant la structure en triple hélice du collagène de type III. Des variants d'un site d'épissage, des insertions-délétions sont également rencontrées, et plus rarement des mutations faux-sens n'affectant pas une glycine, ou des mutations responsables d'haploinsuffisance. Les mutations du COL3A1 sont presque exclusivement privées, et une corrélation entre le phénotype observé et les mutations retrouvées n'a jamais été mise en évidence. Nous avons rapporté l'expérience du centre de référence français du SEDv sur 215 patients, et retrouvé une sévérité de la maladie plus importante chez ceux avec une substitution glycine, ou une insertion/délétion du cadre de lecture dans région de la triple hélice comparativement aux autres génotypes: variants responsables d'haploinsuffisance, variants faux-sens n'affectant pas une glycine, ou les altérations des extrémités N ou C-terminales. Par ailleurs, le phénotype de ces 3 derniers groupes de génotype ne rassemblait pas l'ensemble des symptômes habituellement décrits dans le SEDv et notamment pas de complication digestive. Afin de mieux comprendre l'altération des propriétés biomécaniques de la paroi artérielle des patients atteints de SEDv nous avons utilisé une nouvelle technologie ultrasonore, ultrafastécho, permettant de visualiser et mesurer la vitesse de l'onde de pouls (VOP) localement au niveau carotidien et tout au long du cycle cardiaque. La VOP est un marqueur de rigidité artérielle bien étudié dans l'athérosclérose, et connu pour être un facteur indépendant de mortalité cardiovasculaire. Nous avons établi des valeurs normales des paramètres de l'ultrafastécho chez 102 volontaires sains et analysés 37 patients avec SEDv. Cette étude n'a pas retrouvé de différence de la VOP, donc de rigidité artérielle, en début de systole. En revanche, au cours du cycle cardiaque on a pu observer une moindre rigidification de la paroi artérielle avec l'augmentation de la pression artérielle chez les patients SEDv. Nous avons poursuivi nos explorations par ultrafastécho sur un modèle murin haploinsuffisant pour le collagène de type III (souris Col3a1 hétérozygote) et retrouvé le même profil de réponse. En effet une moindre augmentation de la rigidité artérielle alors que la pression artérielle était augmentée par perfusion de vasopresseur était constatée chez les souris col3a1 hétérozygotes comparativement aux souris sauvages. En conclusion, l'altération du collagène de type III dans le SEDv affecte les propriétés biomécaniques de la paroi artérielle des patients, avec notamment une moindre rigidification lors de l'augmentation de la pression artérielle. Nos travaux ont permis d’affiner la physiopathologie du SEDv, de préciser le phénotype vasculaire par une nouvelle mesure de la VOP et ouvrent des pistes de recherche thérapeutiques d'un traitement augmentant la rigidité artérielle afin de tenter de réduire les risques de ruptures artérielles. / Vascular Elhers-Danlos syndrome (vEDS) is an autosomal dominant genetic vascular disease, affecting the collagen type III, a component in the extracellular matrix of the arterial wall. Patients with vEDS are prone to arterial, intestine or uterine ruptures, which explain the severity of the disease. Mutations in COL3A1, gene encoding for collagen type III are usually heterozygous missense mutations responsible for the substitution of a glycine amino acid for another, which affects the triple helical conformational structure of the collagen type III. Variants of a splice site, deletions/insertions, are also encountered, and more rarely missense mutations not affecting a glycine residue, or alterations responsible for haploinsufficiency. The COL3A1 mutations are almost exclusively private, and a genotype/phenotype correlation has not been clearly studied. We reported the experience of the French reference center for vEDS of 215 patients and found a greater severity of the disease in those with a glycine substitution, or in frame insertion / deletion within the triple helix domain than in other genotypes: responsible variants of haploinsufficiency, missense variants not affecting glycine, or alteration of the N- or C-terminal ends. Furthermore, the phenotype of these last three genotype groups did not combine the complete phenotype described in vEDS especially no gastrointestinal complication. To better understand the alteration of the biomechanical properties of the arterial wall of patients with vEDS we used a new ultrasound technology, ultrafastecho, to visualize and measure the pulse wave velocity (PWV) locally on carotids, over the cardiac cycle. The PWV is a marker of arterial stiffness studied in atherosclerosis, and well known to be an independent risk factor for cardiovascular mortality. We have established normal values ultrafastecho parameters in 102 healthy volunteers and 37 patients with vEDS. This study found no difference in PWV, thus arterial stiffness, in early systole cardiac at diastolic blood pressure. However, in patients with vEDS, weaker stiffening of the arterial wall was observed when blood pressure increases during the cardiac cycle. We continued our explorations by ultrafastecho on a mouse model of vEDS, haploinsufficient for the collagen type III (Col3a1 heterozygous mice). We figured out that Col3a1 heterozygous mice presented the same response profile. Indeed a smaller increase in arterial stiffness while blood pressure was increasing secondary to vasopressor infusion was revealed in the mice compared to the wild mice. In conclusion, alterations of collagen type III in the vEDS affect the biomechanical properties of the arterial wall of the patient, through lower stiffening during the increase of blood pressure over the cardiac cycle. This provides a therapeutic approach for targeting treatment increasing arterial stiffness in vEDS in order to reduce the risk of arterial rupture.

Made available in DSpace on 2015-07-22T20:49:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-05-26. Added 1 bitstream(s) on 2015-08-11T03:26:03Z : No. of bitstreams: 1 Publico-12542.pdf: 1298581 bytes, checksum: c93d3b1854a9178225ef23685647d105 (MD5) / Objetivo: verificar a possível associação entre a presença do polimorfismo no exon 31 do gene do COL3A1 e a ocorrência de prolapso genital em uma amostra da população brasileira. Casuística e Métodos: estudo caso controle envolvendo 316 pacientes estadiadas para prolapso genital, utilizando-se o sistema de quantificação de prolapso dos órgãos pélvicos (POP-Q), padronizado pela Sociedade Internacional de Continência (ICS). O grupo caso foi constituído por 107 pacientes nos estádios III e IV e o grupo controle por 209 mulheres nos estádios 0 e I. Aplicouse a estas pacientes a anamnese dirigida, com o objetivo de avaliar a presença ou não dos principais fatores de risco para prolapso genital (história obstétrica, idade da menopausa, história familiar, tosse crônica e constipação intestinal). Foi realizada, ainda, coleta de 5 ml de sangue periférico para extração do DNA leucocitário. O fragmento a ser estudado (exon 31 do gene do COL3A1) foi amplificado por meio de reação de polimerase em cadeia (PCR). Para a comparação das variáveis qualitativas foi utilizado o teste de Qui-quadrado (X2). Para as variáveis quantitativas foi optado pelo teste de Mann-Whitney U, já que estas variáveis não tiveram padrão de distribuição normal na população. Para o cálculo do valor de odds ratio e Intervalos de Confiança foi utilizada Regressão Logística Binária. O valor de significância estatística estabelecido foi de 5%, ou p<0,05 e o intervalo de confiança foi de 95% (95% IC). Os indivíduos homozigotos mutados e heterozigotos foram analisados e englobados em um só grupo e comparados com os homozigotos selvagens para a alteração genética pesquisada. Toda a análise estatística foi realizada com o software Statistical Package for Social Sciences, version 14.0. Resultados: Com relação às variáveis quantitativas, foram observadas diferenças significativas para todas (p<0,05), com exceção da idade da menopausa. Já na análise das variáveis qualitativas, observamos que só houve diferença significante para as mulheres que apresentavam história familiar de prolapso genital. Não houve diferença estatisticamente significante quanto à presença do polimorfismo em questão em ambos os grupos estudados, considerando que os genótipos em estudo encontravam-se em Equilíbrio de Hardy-Weinberg. Conclusão: a presença de polimorfismo no exon 31 da cadeia alfa 1 do gene do colágeno tipo III não é fator de risco para prolapso genital na amostra da população brasileira estudada. / Objective: To verify the possible association between the presence of the polymorphism in exon 31 of COL3A1 gene and the occurrence of genital prolapse in a sample of the population. Methods: case-control study involving 316 patients staged for pelvic organ prolapse, using the system for quantification of pelvic organ prolapse (POP-Q), standardized by the International Continence Society (ICS). The case group consisted of 107 patients with stage III and IV and the control group of 209 women at stages 0 and I. Was applied to these patients anamnesis, in order to assess the presence or absence of major risk factors for genital prolapse (obstetric history, age at menopause, family history, chronic cough and constipation). There was also, collecting 5 ml of peripheral blood leukocyte DNA extraction. The fragment to be studied (exon 31 of COL3A1 gene) was amplified by the polymerase chain reaction (PCR). To compare the qualitative variables we used the chi square (X2). For quantitative variables was chosen by the Mann - Whitney U, as these variables had normal distribution pattern in the population. For the calculation of odds ratios and confidence intervals was used binary logistic regression. The value of statistical significance was set at 5% or p <0.05 and confidence interval was 95% (95% CI). The homozygous and heterozygous mutant were analyzed and grouped into one group and compared with the homozygous wild for the gene studied. All statistical analysis was performed with the Statistical Package for Social Sciences, version 14.0. Results: With respect to quantitative variables, significant differences were observed for all (p <0.05), except for age of menopause. In the analysis of qualitative variables, we found that only significant difference for women who had a family history of prolapse. There was no statistically significant difference regarding the presence of the polymorphism in question in both groups, whereas the genotypes studied were in Hardy-Weinberg. Conclusion: The presence of a polymorphism in exon 31 of alpha chain 1 gene of collagen type 3 is not a risk factor for pelvic organ prolapse in the Brazilian population studied. / TEDE / BV UNIFESP: Teses e dissertações