BET Signaling:A Novel Therapeutic Target for Pulmonary Hypertension? Reply

Therapeutic cell differentiatio

More Insights into the Association between RVX-208 and Pulmonary Arterial Hypertension Reply

Therapeutic cell differentiatio

Decreased lung fibroblast growth factor 18 and elastin in human congenital diaphragmatic hernia and animal models.

International audienceRATIONALE: Lung hypoplasia in congenital diaphragmatic hernia (CDH) seems to involve impaired alveolar septation. We hypothesized that disturbed deposition of elastin and expression of fibroblast growth factor 18 (FGF18), an elastogenesis stimulus, occurs in CDH. OBJECTIVES: To document FGF18 and elastin in human CDH and ovine surgical and rat nitrofen models and to use models to evaluate the benefit of treatments. METHODS: Human CDH and control lungs were collected post mortem. Diaphragmatic hernia was created in sheep at 85 days; fetal lungs were collected at 139 days (term = 145 days). Pregnant rats received nitrofen at 12 days; fetal lungs were collected at 21 days (term = 22 days). Some of the sheep fetuses with hernia underwent tracheal occlusion (TO); some of the nitrofen-treated pregnant rats received vitamin A. Both treatments are known to promote lung growth. MEASUREMENTS AND MAIN RESULTS: Coincidental with the onset of secondary septation, FGF18 protein increased threefold in control human lungs, which failed to occur in CDH. FGF18 labeling was found in interstitial cells of septa. Elastin staining demonstrated poor septation and markedly decreased elastin density in CDH lungs. Consistently, lung FGF18 transcripts were diminished 60 and 83% by CDH in sheep and rats, respectively, and elastin density and expression were diminished. TO and vitamin A restored FGF18 and elastin expression in sheep and rats, respectively. TO restored elastin density. CONCLUSIONS: Impaired septation in CDH is associated with decreased FGF18 expression and elastic fiber deposition. Simultaneous correction of FGF18 and elastin defects by TO and vitamin A suggests that defective elastogenesis may result, at least partly, from FGF18 deficiency

Surfactant Maturation Is Not Delayed in Human Fetuses with Diaphragmatic Hernia

In an autopsy study of human fetuses, Jacques Bourbon and colleagues report that pulmonary surfactant content is not decreased in congenital diaphragmatic hernia

Matrix Metalloproteinase Gene Polymorphisms and Bronchopulmonary Dysplasia: Identification of MMP16 as a New Player in Lung Development

International audienceBACKGOUND: Alveolarization requires coordinated extracellular matrix remodeling, a process in which matrix metalloproteinases (MMPs) play an important role. We postulated that polymorphisms in MMP genes might affect MMP function in preterm lungs and thus influence the risk of bronchopulmonary dysplasia (BPD). METHODS AND FINDINGS: Two hundred and eighty-four consecutive neonates with a gestational age of <28 weeks were included in this prospective study. Forty-five neonates developed BPD. Nine single-nucleotide polymorphisms (SNPs) were sought in the MMP2, MMP14 and MMP16 genes. After adjustment for birth weight and ethnic origin, the TT genotype of MMP16 C/T (rs2664352) and the GG genotype of MMP16 A/G (rs2664349) were found to protect from BPD. These genotypes were also associated with a smaller active fraction of MMP2 and with a 3-fold-lower MMP16 protein level in tracheal aspirates collected within 3 days after birth. Further evaluation of MMP16 expression during the course of normal human and rat lung development showed relatively low expression during the canalicular and saccular stages and a clear increase in both mRNA and protein levels during the alveolar stage. In two newborn rat models of arrested alveolarization the lung MMP16 mRNA level was less than 50% of normal. CONCLUSIONS: MMP16 may be involved in the development of lung alveoli. MMP16 polymorphisms appear to influence not only the pulmonary expression and function of MMP16 but also the risk of BPD in premature infants

Effects of Phosphodiesterase 4 Inhibition on Alveolarization and Hyperoxia Toxicity in Newborn Rats

International audienceBACKGROUND: Prolonged neonatal exposure to hyperoxia is associated with high mortality, leukocyte influx in airspaces, and impaired alveolarization. Inhibitors of type 4 phosphodiesterases are potent anti-inflammatory drugs now proposed for lung disorders. The current study was undertaken to determine the effects of the prototypal phosphodiesterase-4 inhibitor rolipram on alveolar development and on hyperoxia-induced lung injury. METHODOLOGY/FINDINGS: Rat pups were placed under hyperoxia (FiO2>95%) or room air from birth, and received rolipram or its diluent daily until sacrifice. Mortality rate, weight gain and parameters of lung morphometry were recorded on day 10. Differential cell count and cytokine levels in bronchoalveolar lavage and cytokine mRNA levels in whole lung were recorded on day 6. Rolipram diminished weight gain either under air or hyperoxia. Hyperoxia induced huge mortality rate reaching 70% at day 10, which was prevented by rolipram. Leukocyte influx in bronchoalveolar lavage under hyperoxia was significantly diminished by rolipram. Hyperoxia increased transcript and protein levels of IL-6, MCP1, and osteopontin; rolipram inhibited the increase of these proteins. Alveolarization was impaired by hyperoxia and was not restored by rolipram. Under room air, rolipram-treated pups had significant decrease of Radial Alveolar Count. CONCLUSIONS: Although inhibition of phosphodiesterases 4 prevented mortality and lung inflammation induced by hyperoxia, it had no effect on alveolarization impairment, which might be accounted for by the aggressiveness of the model. The less complex structure of immature lungs of rolipram-treated pups as compared with diluent-treated pups under room air may be explained by the profound effect of PDE4 inhibition on weight gain that interfered with normal alveolarization

Genetic counselling and testing in pulmonary arterial hypertension:a consensus statement on behalf of the International Consortium for Genetic Studies in PAH

Pulmonary arterial hypertension (PAH) is a rare disease that can be caused by (likely) pathogenic germline genomic variants. In addition to the most prevalent disease gene, BMPR2 (bone morphogenetic protein receptor 2), several genes, some belonging to distinct functional classes, are also now known to predispose to the development of PAH. As a consequence, specialist and non-specialist clinicians and healthcare professionals are increasingly faced with a range of questions regarding the need for, approaches to and benefits/risks of genetic testing for PAH patients and/or related family members. We provide a consensus-based approach to recommendations for genetic counselling and assessment of current best practice for disease gene testing. We provide a framework and the type of information to be provided to patients and relatives through the process of genetic counselling, and describe the presently known disease causal genes to be analysed. Benefits of including molecular genetic testing within the management protocol of patients with PAH include the identification of individuals misclassified by other diagnostic approaches, the optimisation of phenotypic characterisation for aggregation of outcome data, including in clinical trials, and importantly through cascade screening, the detection of healthy causal variant carriers, to whom regular assessment should be offered.</p

Multiple Promoters and Alternative Splicing: Hoxa5 Transcriptional Complexity in the Mouse Embryo

The genomic organization of Hox clusters is fundamental for the precise spatio-temporal regulation and the function of each Hox gene, and hence for correct embryo patterning. Multiple overlapping transcriptional units exist at the Hoxa5 locus reflecting the complexity of Hox clustering: a major form of 1.8 kb corresponding to the two characterized exons of the gene and polyadenylated RNA species of 5.0, 9.5 and 11.0 kb. This transcriptional intricacy raises the question of the involvement of the larger transcripts in Hox function and regulation.We have undertaken the molecular characterization of the Hoxa5 larger transcripts. They initiate from two highly conserved distal promoters, one corresponding to the putative Hoxa6 promoter, and a second located nearby Hoxa7. Alternative splicing is also involved in the generation of the different transcripts. No functional polyadenylation sequence was found at the Hoxa6 locus and all larger transcripts use the polyadenylation site of the Hoxa5 gene. Some larger transcripts are potential Hoxa6/Hoxa5 bicistronic units. However, even though all transcripts could produce the genuine 270 a.a. HOXA5 protein, only the 1.8 kb form is translated into the protein, indicative of its essential role in Hoxa5 gene function. The Hoxa6 mutation disrupts the larger transcripts without major phenotypic impact on axial specification in their expression domain. However, Hoxa5-like skeletal anomalies are observed in Hoxa6 mutants and these defects can be explained by the loss of expression of the 1.8 kb transcript. Our data raise the possibility that the larger transcripts may be involved in Hoxa5 gene regulation.Our observation that the Hoxa5 larger transcripts possess a developmentally-regulated expression combined to the increasing sum of data on the role of long noncoding RNAs in transcriptional regulation suggest that the Hoxa5 larger transcripts may participate in the control of Hox gene expression

Mécanismes moléculaires du développement du parenchyme pulmonaire (altérations dans la dysplasie bronchopulmonaire et la hernie de coupole diaphragmatique)

Si le développement fœtal du poumon lui permet d assumer immédiatement les échanges gazeux dès la naissance, le développement de l organe est loin d être achevé, non seulement en ce qui concerne naturellement sa croissance, mais aussi sa morphogenèse. La formation des alvéoles définitives par subdivision des sacs alvéolaires primitifs (alvéolisation) débute in utero, mais la majeure partie du processus va se dérouler après la naissance. Du fait de son immaturité et de sa grande vulnérabilité aux agressions, le poumon du nouveau-né prématuré ventilé lors d une détresse respiratoire aiguë est exposé à un risque important de développer une dysplasie bronchopulmonaire (DBP), dont la principale caractéristique est une grave perturbation du processus d alvéolisation. D autres pathologies, les hypoplasies pulmonaires congénitales, sont aussi susceptibles d entraver le développement alvéolaire. Leur cause la plus fréquente est la hernie de coupole diaphragmatique (HCD) dans laquelle les viscères herniés exercent sur le poumon une compression qui entrave son développement. En dépit des progrès de la médecine périnatale, la morbidité et la mortalité néonatales associées à ces deux pathologies restent élevées. La prévention et le traitement de ces pathologies passe par une meilleure connaissance des mécanismes cellulaires et moléculaires qui sous-tendent le processus d alvéolisation. Afin de progresser dans la compréhension des mécanismes, de nouveaux acteurs ont été recherchés. Dans ce travail, il a été montré : - que le FGF18 est augmenté pendant la période d alvéolisation et qu il stimule de façon coordonnée l expression de divers éléments de l élastogenèse dans les myofibroblastes en culture. - que l expression du FGF18 est diminuée dans un modèle d arrêt de l alvéolisation et chez les fœtus porteurs d une HCD ainsi que dans ses modèles expérimentaux. - que deux traitements de l hypoplasie pulmonaire, l occlusion trachéale foetale chez l ovin et l administration de Vitamine A chez le rat, rétablissent les niveaux d expression du FGF18 et de la tropoélastine. D autre part, par une approche systématique du transcriptome, on a recherché de nouveaux gènes impliqués dans l alvéolisation. L étude a permis d identifier des molécules potentiellement importantes pour le processus et dont le rôle n était pas suspecté auparavant. Un premier groupe de gènes, dont l expression est stimulée pendant l alvéolisation, comprend les facteurs de transcription Hoxa2, a4 et a5 ainsi que les médiateurs diffusibles Wnt5a et NDP. Le second groupe rassemble des gènes dont l expression est réprimée pendant la septation alvéolaire. Il s agit notamment de molécules associées à la matrice extracellulaire (ostéopontine et ostéoactivine) et d un médiateur diffusible Schlafen-4. Dans deux modèles animaux d altération du développement alvéolaire, l expression des gènes du premier groupe était diminuée alors que celle du second groupe était augmentée. Pris dans leur ensemble, ces résultats révèlent l implication de nouveaux gènes dans le développement alvéolaire et suggèrent que des altérations de leur expression pourraient rendre compte des désordres caractéristiques de l HCD et de la DBP. L exploration de leur rôle devrait ouvrir des perspectives nouvelles pour stimuler la croissance et la maturation, faciliter la réparation et éventuellement induire la régénération des poumons. Parallèlement à ce travail, il a été montré que les poumons de nouveau-nés porteurs d une HCD ne semblent pas déficitaires en surfactant contrairement à l opinion qui prédomine. La chronologie et le taux d accumulation des divers constituants ne semblent pas altérés. La supplémentation en surfactant à la naissance dans la HCD pourrait donc être superflue, voire contre-indiquée.PARIS12-Bib. électronique (940280011) / SudocSudocFranceF