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

Hypertension Is Associated with Marked Alterations in Sphingolipid Biology: A Potential Role for Ceramide

Background Hypertension is, amongst others, characterized by endothelial dysfunction and vascular remodeling. As sphingolipids have been implicated in both the regulation of vascular contractility and growth, we investigated whether sphingolipid biology is altered in hypertension and whether this is reflected in altered vascular function. Methods and Findings In isolated carotid arteries from spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats, shifting the ceramide/S1P ratio towards ceramide dominance by administration of a sphingosine kinase inhibitor (dimethylsphingosine) or exogenous application of sphingomyelinase, induced marked endothelium-dependent contractions in SHR vessels (DMS: 1.4±0.4 and SMase: 2.1±0.1 mN/mm; n = 10), that were virtually absent in WKY vessels (DMS: 0.0±0.0 and SMase: 0.6±0.1 mN/mm; n = 9, p Conclusions Hypertension is associated with marked alterations in vascular sphingolipid biology such as elevated ceramide levels and signaling, that contribute to increased vascular tone

Familial hypercholesterolaemia in children and adolescents from 48 countries: a cross-sectional study

Background: Approximately 450 000 children are born with familial hypercholesterolaemia worldwide every year, yet only 2·1% of adults with familial hypercholesterolaemia were diagnosed before age 18 years via current diagnostic approaches, which are derived from observations in adults. We aimed to characterise children and adolescents with heterozygous familial hypercholesterolaemia (HeFH) and understand current approaches to the identification and management of familial hypercholesterolaemia to inform future public health strategies. Methods: For this cross-sectional study, we assessed children and adolescents younger than 18 years with a clinical or genetic diagnosis of HeFH at the time of entry into the Familial Hypercholesterolaemia Studies Collaboration (FHSC) registry between Oct 1, 2015, and Jan 31, 2021. Data in the registry were collected from 55 regional or national registries in 48 countries. Diagnoses relying on self-reported history of familial hypercholesterolaemia and suspected secondary hypercholesterolaemia were excluded from the registry; people with untreated LDL cholesterol (LDL-C) of at least 13·0 mmol/L were excluded from this study. Data were assessed overall and by WHO region, World Bank country income status, age, diagnostic criteria, and index-case status. The main outcome of this study was to assess current identification and management of children and adolescents with familial hypercholesterolaemia. Findings: Of 63 093 individuals in the FHSC registry, 11 848 (18·8%) were children or adolescents younger than 18 years with HeFH and were included in this study; 5756 (50·2%) of 11 476 included individuals were female and 5720 (49·8%) were male. Sex data were missing for 372 (3·1%) of 11 848 individuals. Median age at registry entry was 9·6 years (IQR 5·8-13·2). 10 099 (89·9%) of 11 235 included individuals had a final genetically confirmed diagnosis of familial hypercholesterolaemia and 1136 (10·1%) had a clinical diagnosis. Genetically confirmed diagnosis data or clinical diagnosis data were missing for 613 (5·2%) of 11 848 individuals. Genetic diagnosis was more common in children and adolescents from high-income countries (9427 [92·4%] of 10 202) than in children and adolescents from non-high-income countries (199 [48·0%] of 415). 3414 (31·6%) of 10 804 children or adolescents were index cases. Familial-hypercholesterolaemia-related physical signs, cardiovascular risk factors, and cardiovascular disease were uncommon, but were more common in non-high-income countries. 7557 (72·4%) of 10 428 included children or adolescents were not taking lipid-lowering medication (LLM) and had a median LDL-C of 5·00 mmol/L (IQR 4·05-6·08). Compared with genetic diagnosis, the use of unadapted clinical criteria intended for use in adults and reliant on more extreme phenotypes could result in 50-75% of children and adolescents with familial hypercholesterolaemia not being identified. Interpretation: Clinical characteristics observed in adults with familial hypercholesterolaemia are uncommon in children and adolescents with familial hypercholesterolaemia, hence detection in this age group relies on measurement of LDL-C and genetic confirmation. Where genetic testing is unavailable, increased availability and use of LDL-C measurements in the first few years of life could help reduce the current gap between prevalence and detection, enabling increased use of combination LLM to reach recommended LDL-C targets early in life

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

INTERACTIONS EPITHELIUM-MESENCHYME DANS LA MATURATION DE L'EPITHELIUM ALVEOLAIRE. ROLE DU KERATINOCYTE GROWTH FACTOR ET DES RETINOIDES

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF