The Role of Bcl-2 in Hyperoxia-Induced Cell Death

Dans un cadre thérapeutique, l’oxygène est indispensable dans le traitement des patients souffrant de lésions aigues du poumon. Cependant, l’exposition à un taux élevé d’oxygène induit la production de radicaux libres à plus ou moins long terme avec l'apparition de lésions aigues du poumon. Celles-ci peuvent par la suite mener à un syndrome de détresse respiratoire défini par des critères radiologiques (présence d’infiltrats) et physiologiques (hypoxémie, dyspnée, détresse respiratoire). L’expression physiopathologique de ces lésions aigues provient d’un trouble de la perméabilité capillaire affectant la capacité de diffusion des alvéoles. Dans les formes les plus sévères de ce syndrome, la complète destruction de la barrière alvéolo-capillaire est la conséquence de lésions cellulaires majeures, entraînant une altération structurale pulmonaire, parfois irréversible. Lors de cette thèse, nous avons étudié les différents mécanismes de mort cellulaire qui sont l'apoptose et la nécrose, lors de l'exposition à l'hyperoxie

Etude du Rôle de PARP-1 dans la Mort Cellulaire Induite par l’Oxygène

Dans un cadre thérapeutique, l’oxygène est indispensable dans le traitement des patients souffrant de lésions aiguës du poumon. Cependant, l’exposition à un taux élevé d’oxygène induit la production de radicaux libres à plus ou moins long terme. Les radicaux libres endommagent les lipides membranaires, les protéines, ainsi que l’intégrité de l’ADN cellulaires. Ils peuvent affecter la cellule jusqu’à provoquer sa mort. Deux types de mort cellulaires sont décrits à ce jour : l’apoptose et la nécrose. Lors de ce travail de thèse, nous avons étudié le rôle essentiel des Poly- ADP ribosyl polymerase (PARP), enzymes nucléaires impliquées dans la réparation de l’ADN, ainsi que dans la mort cellulaire. Nous nous sommes plus particulièrement intéressés à PARP-1, enzyme contrôlant la réparation cellulaire et le remodelage tissulaire, lors de lésions pulmonaires dues à l'hyperoxie. Nous avons finalement étudié les différents mécanisme de mort cellulaire dans ces conditions

Insights on congenital pulmonary and thoracic anomalies

Congenital pulmonary and thoracic anomalies are rare malformations present from birth, with sometimes clinical manifestations later in life. Understanding the etiology of these malformations is important both for their management and for the anticipation of their clinical evolution. In this context, the study of embryogenesis and the various factors influencing pulmonary development could guide the therapeutic decisions proposed to these patients. The objective of this manuscript is to review the state of knowledge on the different pulmonary malformations from a clinical and translational standpoint and to discuss research perspectives. The manuscript includes five scientific papers. The one focuses on the tracheal bronchi observed from 5,970 children who underwent bronchoscopy for respiratory examinations. The subsequent results allowed improving clinical knowledge of such malformation. The second article is dedicated to the study of pulmonary hypoplasia in patients with congenital heart disease (CHD). Data obtained on 119 fetuses with CHD were prospectively examined for cardiac and pulmonary abnormalities. The results suggests that an altered interaction between endothelial cells, the surrounding epithelium and the mesenchyma could influence the development of pulmonary hypoplasia without an abnormality of the pulmonary vascular system. The third paper focuses on the potential neonatal consequences of congenital pulmonary anomalies (CPAM). The analysis of various parameters (ratio of maximum CPAM volume, polyhydramnios and ascites) is proposed to predict CPAM evolution and to define the requirement of a tertiary care center for delivery. The fourth paper describes the role and importance of a database and a related biobank in the study of rare diseases such as congenital pulmonary anomalies. The last article is dedicated to the study of paraffin-embedded samples of CPAM using immunostaining and proteomic analyses. Results show that there is no clear correlation between the CPAM origins and their onset during embryogenesis. The understanding of the interactions between lung cells during embryogenesis seems to be a key step to anticipate malformations to occur and to improve patient’s follow-up. The papers included in this manuscript open new perspective for clinical and translational studies

Etude du rôle de PARP-1 dans la mort cellulaire induite par l'oxygène

Les lésions aigues du poumon sont consécutives à différentes étiologies, dont l'exposition à des concentrations élevées en oxygène. Le stress oxydatif résultant de l'hyperoxie induit la mort des cellules endothéliales, formant la barrière alvéolo-capillaire, responsable des échanges gazeux pulmonaires. Dans ce travail nous avons étudié le rôle de la molécule Poly- (ADP-Ribose) Polymerase-1 (PARP-1) impliqué dans la réparation de l'ADN, ainsi que dans la mort cellulaire. Dans cette optique, nous avons étudié le rôle de PARP-1 dans la mort cellulaire induite par l'oxygène, ainsi que dans la répartition cellulaire "in vitro" et "in vivo". Nos résultats démontrent le rôle essentiel de PARP-1 dans le contrôle de la réparation cellulaire et le remodelage tissulaire, induit lors de lésions pulmonaires dues à l'oxygène. Cependant, le rôle de PARP-1 dans le mécanisme aigu de mort cellulaire semble complexe et dépendant du type cellulaire analysé

Presence of tracheal bronchus in children undergoing flexible bronchoscopy

Background and objectives: Tracheal bronchus (TB) is a rare congenital malformation of the lung tree with a bronchus originating from the trachea. Only a small number of publications have analyzed the frequency and diagnostic procedure of TB in children, based on a restricted sample of patients. In the present study, we analyze and discuss new aspects of prevalence, clinical presentation and associated malformations of TB based on a large pediatric cohort. Methods: Data from 5970 children having a flexible bronchoscopy for investigation of respiratory symptoms were selected. We analyzed the anesthesic management, the presence of associated malformations, and all tracheobronchial anomalies observed during the endoscopic procedure. Results: Fifty-seven cases of tracheal bronchus were identified (0.9%). In the majority of them, tracheal bronchus was a fortuitous discovery without clear clinical relevance. Statistical analysis revealed that the majority of TB originated from the middle and lower one third of the trachea (56%). 61.5% of patients had associated anomalies such as syndromic association (21%), cardiac malformations (19.2%) or tracheal stenosis (14%). Only 38.5% of children had no associated anomalies. Conclusions: Tracheal bronchus is a rare morphological anomaly of the tracheobronchial tree. Most often TB is associated with other birth defects such as another tracheo-bronchial tree malformation, vascular abnormality, congenital heart malformation or in the context of a syndromic pattern. A relationship between respiratory symptoms and the presence of TB is very rare and selective treatment is infrequent

Prime Implicate Generation in Equational Logic

International audienceA procedure is proposed to efficiently generate sets of ground implicates of first-order formulas with equality. It is based on a tuning of the superposition calculus [Nieuwenhuis and Rubio, 2001], enriched with rules that add new hypotheses on demand during the proof search. Experimental results are presented , showing that the proposed approach is more efficient than state-of-the-art systems

Mitochondrial cytochrome c release is a key event in hyperoxia-induced lung injury: protection by cyclosporin A.

Hyperoxia is known to induce extensive alveolar cell death by still poorly defined mechanisms. In this study, the mitochondria-dependent cell death pathway was explored during hyperoxia-induced lung injury in mice. We observed a progressive release of cytochrome c from the mitochondria into the cytosol of alveolar cells. This release was accompanied by the translocation of the proapoptotic protein Bax from cytosol to mitochondria without detectable activation of caspase-3. As cytochrome c release can be induced by mitochondrial membrane alteration and permeability transition (MPT), mice were treated with cyclosporin A, which specifically inhibits MPT. Cyclosporin A treatment prevented mitochondrial release of cytochrome c during hyperoxia and concomitantly preserved mitochondria from extensive swelling and crista disorganization, as assessed by electron microscopy analysis of alveolar epithelial cells. These morphological and biochemical observations correlated with decreased lung tissue damage, as evaluated by morphological score and lung weight. In conclusion, mitochondrial damage and cytochrome c release are important linked events in hyperoxia-induced lung injury and can be efficiently blocked by cyclosporin A

Gestation and lactation exposure to nicotine induces transient postnatal changes in lung alveolar development.

Harmful consequences of cigarette smoke (CS) exposure during lung development can already manifest in infancy. In particular, early life exposure to nicotine, the main component of CS, was shown to affect lung development in animal models. We aimed to characterize the effect of nicotine on alveoli formation. We analyzed the kinetics of normal alveolar development during the alveolarization phase and then looked at the effect of nicotine in a mouse model of gestational and early life exposure. Immunohistochemical staining revealed that the wave of cell proliferation (i.e. vascular endothelial cells, alveolar epithelial cells (AEC) type II and mesenchymal cell) occurs at pnd8 in control and nicotine-exposed lungs. However, FACS analysis of individual epithelial alveolar cells revealed nicotine-induced transient increase of AEC type I proliferation and decrease of vascular endothelial cell proliferation at pnd8. Furthermore, nicotine increased the percentage of endothelial cells at pnd2. Transcriptomic data also showed significant changes in nicotine samples compared to the controls on cell cycle associated genes at pnd2, but not anymore at pnd16. Accordingly, the expression of survivin, involved in cell cycle regulation, also follows a different kinetics in nicotine lung extracts. These changes resulted in an increased lung size detected by stereology at pnd16, but no longer in adult age, suggesting that nicotine can act on the pace of lung maturation. Taken together, our results indicate that early life nicotine exposure could be harmful to alveolar development independently from other toxicants contained in CS