INTRODUÇÃO: Picos de pressão inspiratória excessivos e elevados volumes correntes (VT) durante a ventilação manual podem iniciar a resposta inflamatória no pulmão do prematuro. A manobra de insuflação pulmonar sustentada (IPS) tem sido estudada como um procedimento para melhorar a aeração pulmonar imediatamente após o nascimento. OBJETIVO: Avaliar a influência do ventilador manual em T (peça T) e do balão autoinflável (BAI) nas variáveis de mecânica respiratória durante a ventilação manual e a manobra de IPS, além da influência do treinamento como instrutor do Programa de Reanimação Neonatal da Sociedade Brasileira de Pediatria (PRN-SBP), na qualidade da ventilação. MÉTODOS: Em um estudo experimental, prospectivo e randomizado, 114 indivíduos, entre instrutores e não instrutores do PRN-SBP, ventilaram um manequim neonatal intubado, equivalente a um recém-nascido de 2500 gramas, por períodos de três minutos, utilizando um BAI e a peça T. A escolha do primeiro equipamento foi feita por randomização e os operadores não tinham acesso aos dados de mecânica respiratória durante a gravação. Ao final da ventilação manual, foi solicitado que cada indivíduo realizasse uma manobra de IPS durante 10 segundos, a uma pressão de 20 cmH2O. Para cada parâmetro de mecânica respiratória obtido durante a ventilação manual e a IPS, foi realizada uma comparação direta entre os equipamentos, considerando a formação e o treinamento dos participantes. Os dados foram obtidos por um sistema informatizado que permitiu a análise posterior. RESULTADOS: Em relação à ventilação manual, foi encontrada uma diferença nos valores do VT e do TI entre os equipamentos. Com o uso do BAI o VT foi de 28,5 (12,6) mL, mediana (amplitude interquartil) no grupo instrutores e 31,6 (14,0) mL no grupo não instrutores, enquanto que com a peça T foi de 20,1 (8,4) mL e 22,3 (8,8) mL, respectivamente. O TI encontrado com o uso do BAI foi de 0,5 (0,2) segundos, mediana (amplitude interquartil), tanto para instrutores como para não instrutores, enquanto que com a peça T foi de 1,0 (0,6) segundos e 1,1 (0,9) segundos, respectivamente. Em ambos os parâmetros não foram observadas diferenças entre os grupos de profissionais. A capacidade do operador de manter uma pressão alvo de 20 cmH2O durante os 10 segundos de IPS foi avaliada através da área sob a curva de pressão (ASC), que foi 1,7 vezes maior com o uso da peça T em relação ao BAI (p < 0,05). A pressão inspiratória máxima aplicada para a realização da IPS foi maior com o uso do BAI, enquanto que a pressão média das vias aéreas, avaliada entre o início e o final dos 10 segundos de procedimento, foi maior com o uso da peça T. Novamente não foram observadas diferenças entre os grupos de profissionais. CONCLUSÃO: A peça T resultou em menores valores de VT e maiores valores de TI independente do treinamento como instrutor do PRNSBP. A peça T permitiu uma maior eficácia na realização da manobra de IPS, representada pela manutenção da pressão alvo pelo período desejado e por uma maior pressão média nas vias aéreas em relação ao BAI / INTRODUCTION: During manual resuscitation of neonates, excessive peak inspiratory pressure (PI) and high tidal volume (VT) may trigger an inflammatory response in the lungs. The sustained lung inflation (SLI) maneuver has been studied as a procedure to improve pulmonary aeration immediately after birth. OBJECTIVE: To assess the influence of a T-piece manual resuscitator versus a self-inflating bag (SIB) on respiratory mechanics during manual ventilation and the SLI maneuver and the influence of training as a Brazilian Society of Pediatrics Neonatal Resuscitation Program instructor on the quality of ventilation. METHODS: In this experimental, prospective, randomized trial, 114 operators, including Brazilian Society of Pediatrics Neonatal Resuscitation Program instructors and non-instructors, ventilated an intubated neonatal resuscitation trainer (equivalent to a 2500g neonate) for 3-minute periods using an SIB or a Tpiece device. The choice of first device was random, and operators had no access to respiratory mechanics data during recording. At the end of the manual ventilation period, each operator was asked to perform an SLI maneuver for 10 seconds at 20 cmH2O. For each respiratory mechanics parameter obtained during manual ventilation and SLI, a direct comparison between devices was performed, taking operator training into account. Data were obtained through a computerized system for later analysis. RESULTS: During manual ventilation, differences in VT and TI were found between the two devices. The SIB was associated with a median (interquartile range) VT of 28.5 (12.6) mL in the instructor group and 31.6 (14.0) mL in the noninstructor group, whereas the T-piece was associated with a VT of 20.1 (8.4) mL in the instructor group and 22.3 (8.8) mL in the non-instructor group. Regarding TI, the SIB was associated with a median (interquartile range) value of 0.5 (0.2) seconds in instructors and non-instructors alike, whereas the T-piece was associated with a value of 1.0 (0.6) seconds in the instructor group and 1.1 (0.9) seconds in the non-instructor group. No differences between the operator groups were found in either parameter. Operator ability to maintain a 20-cmH2O pressure during the 10-second SLI maneuver was assessed by the area under the pressure curve (AUC), which was 1.7 times greater with the T-piece device than with the SIB (p < 0.05). Peak PI during the SLI maneuver was higher with the SIB, whereas mean airway pressure, assessed between start and end of the 10-second maneuver, was higher with the T-piece. Again, there were no differences between the operator groups. CONCLUSION: The T-piece was associated with lower VT and higher TI values regardless of training as a Brazilian Society of Pediatrics Neonatal Resuscitation Program instructor. The T-piece provided greater efficacy in performing the SLI maneuver, as represented by maintenance of target pressure throughout the desired period and by a higher mean airway pressure as compared with SIB use

Introduction: Le supplément d’oxygène et la nutrition parentérale (NP) sont les deux sources majeures de stress oxydant chez le nouveau-né. Lors de la détoxification des oxydants, le potentiel redox du glutathion s’oxyde. Notre hypothèse est que le supplément d’oxygène et la durée de la NP sont associés à un potentiel redox plus oxydé et à une augmentation de la sévérité de la dysplasie bronchopulmonaire (DBP). Patients et Méthodes: Une étude observationnelle prospective incluant des enfants de moins de 29 semaines d’âge gestationnel. Les concentrations sanguines de GSH et GSSG à jour 6-7 et à 36 semaines d’âge corrigé étaient mesurées par électrophorèse capillaire et le potentiel redox était calculé selon l’équation de Nernst. La sévérité de la DBP correspondait à la définition du NICHD. Résultats: Une FiO2≥ 25% au 7ième jour de vie ainsi que plus de 14 jours de NP sont significativement associés à un potentiel redox plus oxydé et à une DBP plus sévère. Ces relations sont indépendantes de l’âge de gestation et de la gravité de la maladie initiale. La corrélation entre le potentiel redox et la sévérité de la DBP n’est pas significative. La durée de la NP était responsable de 15% de la variation du potentiel redox ainsi que de 42% de la variation de la sévérité de la DPB. Conclusion: Ces résultats suggèrent que l’oxygène et la NP induisent un stress oxydant et que les stratégies visant une utilisation plus judicieuse de l’oxygène et de la NP devraient diminuer la sévérité de la DBP. / Introduction: oxygen supplementation and total parenteral solution (TPN) are two main clinical practices that sustain oxidative stress. Glutathione is a key molecule that detoxifies peroxides resulting in a more oxidized redox potential. We hypothesize that O2 supplementation and longer TPN duration are associated with both more oxidized redox potential and more severe bronchopulmonary dysplasia (BPD). Patients and methods: A prospective observational study including infants of less than 29 weeks gestational age. GSH and GSSG from whole blood sampled on day 6-7 and at 36 weeks of corrected age (CA) were measured by capillary electrophoresis and redox potential was calculated using Nernst equation. BPD was classified according to NICHD guidelines. Results: There was a significant association between FiO2 ≥ 25% on day 7 of life and TPN duration longer than 14 days and both more oxidized redox potential and more severe BPD. TPN duration explained both 15 % of total variation observed in redox potential and 42 % of total variation in BPD severity. These associations remained significant after adjustment for gestational age and illness severity. The relation between the severity of BPD and the redox potential in blood was not significant. The statistic power (1-β) to show an effect of redox potential on severity of BPD was 52%. Conclusion: Both redox potential of glutathione and BPD severity are both associated with early O2 supplement and TPN. Strategies targeting judicious use of O2 supplement and either decreasing the duration or using safer formulation of TPN are expected to help reducing BPD.

Abstract Pulmonary surfactant is a lipid-protein mixture that lines the inner surface of the lung. The main function of surfactant is to reduce surface tension at the air-liquid interface, thus preventing alveolar collapse at the end of expiration. Lack of surfactant is the main cause of respiratory distress syndrome (RDS) in preterm infants. Very preterm babies are at risk of developing a lung disease called bronchopulmonary dysplasia (BPD). The surfactant proteins SP-A, -B, -C and -D have important functions in surfactant structure, homeostasis and innate immunity of the lung. The genes of these proteins have been studied as candidates for several multifactorial lung diseases both in adults and in children. The aim of the present study was to examine the genetic variation in SP genes and to evaluate the role of SP gene polymorphism in the etiology of severe pulmonary infantile diseases, including RDS, BPD and severe respiratory syncytial virus (RSV) infection among the Finnish population. Conventional allelic association methods in combination with multiparameter analysis and family-based transmission disequilibrium test (TDT) were used. The SP-D Met11 allele was associated with a risk for severe RSV bronchiolitis in a matched case-control setting of 84 infants with severe RSV infection and 93 control infants. The variants of the SP-C gene had no detectable association with BPD. However, a modest association of SP-C Asn138 and Asn186 alleles with RDS was found. A length variation in the SP-B gene was associated with BPD among very preterm infants born before 32 weeks of gestation. The SP-B intron 4 deletion variant allele increased the risk for BPD especially in very low birth weight infants. The association was confounded by birth order, being evident only among presenting infants, who are more prone to ascending infections during a preterm birth process. The present study provides new evidence about the significance of SP gene polymorphisms in the etiology of complex infantile pulmonary diseases, including RDS, BPD and severe RSV bronchiolitis. The results help us to understand the molecular mechanisms underlying these diseases and may, in the long run, enable better treatment of these life-threatening diseases. / Tiivistelmä Keuhkosurfaktantti on keuhkon sisäpintaa peittävä kalvomainen rasva-proteiinikompleksi, jonka tärkein ominaisuus on pintajännityksen vähentäminen keuhkorakkuloissa. Surfaktantin puutos ennenaikaisesti syntyneillä lapsilla aiheuttaa hengitysvaikeusoireyhtymän, RDS-taudin (respiratory distress syndrome). Alle 30 raskausviikon iässä syntyneistä, useimmiten RDS-taudin saaneista keskosista n. 30 % sairastuu vakavaan krooniseen keuhkotautiin, BPD-tautiin (bronchopulmonary dysplasia). Surfaktanttiproteiineilla SP-A, -B, -C ja -D on osoitettu olevan tärkeä tehtävä surfaktantin toiminnassa ja keuhkon synnynnäisessä immuniteetissa. Tämän tutkimuksen tavoitteena oli selvittää surfaktanttiproteiineissa esiintyvän geneettisen muuntelun määrää ja merkitystä keskosten RDS- ja BPD-taudeissa sekä pienten lasten vakavassa respiratory syncytial -viruksen (RSV) aiheuttamassa keuhkotulehduksessa. Tutkimuksen laajin osa keskittyi tutkimaan keskosten BPD-tautia ja surfaktanttiproteiinien geenien osuutta siinä. Geneettisen muuntelun merkitystä tarkasteltiin populaatiogeneettisin keinoin tapaus-verrokkiasetelmissa ja perheaineistojen avulla. Yhteensä analysoitiin noin tuhannen lapsen ja yli kahdensadan vanhemman DNA-näytteet. Tutkimuksessa havaittiin SP-D-geenissä olevan metioniini11-geenimuodon liittyvän pienten lasten vakavaan RSV-infektioon. Lisäksi saatiin uutta tietoa SP-C-geenin populaatiotason yleisestä muuntelusta ja todettiin SP-C:n asparagiini138 ja asparagiini186 -geenimuotojen yhteys keskosten RDS-taudin esiintymiseen. Merkittävin löydös oli SP-B-geenissä olevan deleetiovariantin kytkeytyminen alle 32-viikkoisina syntyneiden keskosten BPD-tautiin. Geneettisen altistuksen lisäksi BPD-tautiin sairastumiseen vaikuttivat lukuisat keskosuudelle ominaiset seikat, kuten alhainen syntymäpaino, RDS-tauti ja syntymähetkellä todettu hapenpuute. Geneettisen tekijän vaikutus oli voimakkain erittäin pienipainoisilla keskosilla. Tutkimuksen tulokset ovat tuoneet arvokasta lisätietoa surfaktanttiproteiinien geenien osuudesta keskosten RDS- ja BPD-taudeissa sekä pienten lasten vakavassa RSV-infektiossa. Ne auttavat ymmärtämään näiden molekyylibiologisia syntymekanismeja ja voivat ajan mittaan olla edistämässä uusien hoitomuotojen kehittämistä.

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La dysplasie broncho-pulmonaire (DBP), caractérisée par un défaut de l’alvéolarisation, est une complication pathologique associée à un stress oxydant chez le nouveau-né prématuré. La DBP est présente chez près de 50 % des nouveau-nés de moins de 29 semaines de gestation. La nutrition parentérale (NP) que ces nouveau-nés reçoivent pour cause d’immaturité gastro-intestinale est une source importante de stress oxydant. En effet, leur NP est contaminée par des peroxydes, dont l’ascorbylperoxyde qui est une forme peroxydée du déshydroascorbate. La génération des peroxydes est catalysée par la lumière ambiante. La photoprotection de la NP, quoique difficile d’application en clinique, est associée à une diminution de l’incidence de la DBP chez les enfants prématurés. Chez l’animal nouveau-né, la photoprotection de la NP est associée à un meilleur développement alvéolaire. Ainsi, nous émettons l’hypothèse que l’ascorbylperoxide infusé avec la NP cause la perte d’alvéoles suite à une apoptose exagérée induite par l’oxydation du potentiel redox du glutathion. Cette oxydation du potentiel redox serait occasionnée par l’inhibition de la transformation hépatique de la méthionine en cystéine, menant à une diminution de la synthèse de glutathion au foie et dans les tissus tels que les poumons. La confirmation de cette hypothèse suggérera qu’un ajout de glutathion dans la NP permettra une meilleure détoxification de l’ascorbylperoxide par l’action de la glutathion peroxydase, et préviendra l’oxydation du potentiel redox et ainsi, la perte d'alvéoles par apoptose. Objectifs : Le but de mon projet de recherche est de comprendre les mécanismes biochimiques liant la NP et le développement de la DBP chez le nouveau-né prématuré et de proposer une alternative nutritionnelle prévenant le développement de cette complication fréquemment observée dans cette population. Les objectifs spécifiques sont : 1) d’évaluer l’impact, au poumon, de l’infusion de l’ascorbylperoxyde sur l’axe métabolique potentiel redox du glutathion - apoptose - le développement alvéolaire; 2) d’étudier l’impact de l’ascorbylperoxyde et du potentiel redox sur l’activité hépatique de la méthionine adénosyltransférase (MAT), première enzyme de la cascade métabolique transformant la méthionine en cystéine; et 3) de tenter de prévenir l’impact négatif de la NP ou de l’infusion d’ascorbylperoxyde sur le poumon en améliorant le statut en glutathion. Méthodes: Par un cathéter fixé dans la jugulaire, des cochons d’Inde de trois jours de vie (n = 8 par groupe) ont reçu en continu durant 4 jours une NP ou une solution de base (dextrose + NaCl) enrichie des différentes molécules à l’essai. Le premier objectif a été atteint en enrichissant la solution de base en ascorbylperoxyde à 0, 20, 60 et 180 μM. Ces solutions contenaient ou non 350 μM H2O2 pour se rapprocher des conditions cliniques. Le second objectif a été atteint en investiguant les mécanismes d’inhibition de la MAT dans des animaux infusés ou non avec des solutions contenant la solution de base, des peroxydes, du glutathion et la NP (dextrose + acides aminés + multivitamines + lipides). Le troisième objectif a été atteint en ajoutant ou non à une solution d’ascorbylperoxide ou à la NP 10 μM de glutathion (GSSG), afin d’obtenir une concentration plasmatique normale de glutathion. Après 4 jours, les poumons étaient prélevés et traités pour la détermination de GSH et GSSG par électrophorèse capillaire, le potentiel redox était calculé selon l'équation de Nernst et le niveau de caspase-3 actif (marqueur d’apoptose) par Western blot et l’index d’alvéolarisation quantifié par le nombre d’interceptes entre des structures histologiques et une droite calibrée. Les données étaient comparées par ANOVA, les effets étaient considérés comme significatifs si le p était inférieur à 0,05. Résultats: L’infusion de l’ascorbylperoxyde, indépendamment du H2O2, a induit une hypoalvéolarisation, une activation de la caspase-3 et une oxydation du potentiel redox de manière dose-dépendante. Ces effets ont été empêchés par l’ajout de GSSG à la NP ou à la solution d’ascorbylperoxyde (180 M). L’ascorbylperoxyde et le H2O2 ont inhibé l’activité de MAT tandis qu’elle était linéairement modulée par la valeur du potentiel redox hépatique. Conclusion : Nos résultats suggèrent que l’ascorbylperoxyde est l’agent actif de la NP conduisant au développement de la DBP. Ainsi la correction des bas niveaux de glutathion induits par les peroxydes de la NP favorise la détoxification des peroxydes et la correction du potentiel redox pulmonaire ; ce qui a protégé les poumons des effets délétères de la NP en outrepassant l’inhibition de la MAT hépatique. Nos résultats sont d'une grande importance car ils donnent de l'espoir pour une prévention possible de la DBP. / Bronchopulmonary dysplasia (BPD) is a major complication of preterm newborns, affecting nearly 50% of infants born before 29 weeks of gestation. BPD is characterized by an arrest in alveolar development. The onset of BPD is related to oxidative stress. Research has shown that parenteral nutrition (PN), which is given to preterm newborns to bypass an immature gastrointestinal system, is a major source of oxidative stress. Indeed, PN is contaminated with peroxides, including ascorbylperoxide, an oxidized form of dehydroascorbic acid. Ambient light is a catalyst for the generation of peroxides. Photo-protection of PN, although difficult to apply in the clinical situation, is associated with a lower incidence of BPD in premature infants and with better alveolar outcomes in animal models of neonatal PN. We hypothesized that the ascorbylperoxide in PN disrupts alveolar development. The main mechanism of action is an inhibition of the transformation of methionine into cysteine in the liver, leading to a lower glutathione synthesis in the liver as well as in peripheral tissues such as lung. Lower glutathione (GSH) concentrations favour a shift of redox potential to a more oxidized state and consequently, to exaggerated apoptosis. If our hypothesis is correct, the addition of glutathione to PN would help detoxify ascorbylperoxide through the action of glutathione peroxidase and prevent the deleterious impact of PN. Objectives: The aims of my research project were to investigate the biochemical mechanisms linking PN to the development of BPD in premature newborns and to propose a nutritional alternative that would prevent the occurrence of this frequently observed complication. Specific objectives were: 1) to assess the effect of intravenously infused ascorbylperoxide on the metabolic axis redox potential of glutathione in the lung; specifically, apoptosis and the alveolarization index; 2) to study the impact of ascorbylperoxide and the redox potential on the activity of methionine adenosyltransferase (MAT) in the liver; methionine adenosyltransferase is the first enzyme in the metabolic cascade from methionine to cysteine; and 3) to try to prevent the deleterious impact of PN or ascorbylperoxide infusions on the lung by improving glutathione status. Methods: Through a catheter in the jugular vein, 3-day-old guinea pigs (n = 8 per group) received continuous infusions of PN or a simple solution (dextrose + NaCl) enriched with different molecules for testing. The first objective was achieved by enriching the basic solution with ascorbylperoxide at concentrations of 0, 20, 60 and 180 M. To mimic clinical conditions, these solutions contained, or not, 350 M H2O2. The second objective was achieved by investigating the mechanisms of MAT inhibition in animals infused, or not, with solutions consisting of the basic solution, peroxides, glutathione, and PN (dextrose + amino acids + multivitamins + lipids). The third objective was achieved by adding, or not, 10 M of glutathione (GSSG) to the ascorbylperoxide or PN solution until a normal plasma concentration of glutathione was obtained. After 4 days, the lungs were removed. GSH and GSSG levels in the lungs were determined by capillary electrophoresis. The redox potential was calculated using the Nernst equation. The activation and the concentration of active caspase-3 (marker of apoptosis) were determined by Western blot, and the alveolarization index quantified by the number of intercepts between histological structures and a calibrated straight line. Data were compared by ANOVA; effects were considered significant if p was less than 0.05. Results: The infusion of ascorbylperoxide, independently of H2O2, induced hypoalveolarization, activation of caspase-3, and oxidation of the redox potential, in a dose-dependent manner. These effects were prevented by the addition of GSSG to the ascorbylperoxide (180 M) or PN solutions. Ascorbylperoxide and H2O2 inhibited MAT activity in the liver. Hepatic MAT activity was linearly modulated by the value of the redox potential. Conclusion: Our results suggest that ascorbylperoxide is the active ingredient in PN that leads to the development of BPD. Correcting the low glutathione levels induced by peroxides in PN solutions would promote the detoxification of peroxides and re-establish proper pulmonary redox potentials. Glutathione correction further protects the lungs from the deleterious effects of PN by bypassing hepatic MAT inhibition. This result is of great importance because it gives hope for the possible prevention of BPD.

A necessidade de intubação e uso de ventilação mecânica (VM) na prematuridade está relacionada à chamada lesão pulmonar induzida pela ventilação (VILI) e consequente displasia broncopulmonar (DBP). Estudos com animais e também em humanos mostraram que breves períodos de VM são suficientes para a liberação de interleucinas pró-inflamatórias. Outras formas de VM que regulam o volume-corrente evitando o volutrauma e as ventilações não invasivas como a pressão positiva contínua em via aérea por pronga nasal (CPAPn) parecem medidas protetoras ou menos lesivas para VILI. Esses efeitos protetores do CPAPn não foram ainda estudados em humanos. Objetivo: avaliar os níveis plasmáticos da interleucina (IL)-1β, IL-6, IL-8, IL-10 e fator de necrose tumoral (TNF)-α em recém-nascidos tão logo instituído CPAPn e duas horas após. Secundariamente, avaliação dessa resposta inflamatória em pacientes que necessitaram de VM. Metodologia: estudo de coorte prospectivo, incluindo recém-nascidos admitidos com idade gestacional (IG) de 28-35 semanas e necessidade de assistência ventilatória, excluindo malformações, infecção congênita, sepse, surfactante profilático e suporte ventilatório em sala de parto. Amostras de sangue coletadas nesses dois momentos. Realizada descrição das variáveis em medianas e interquartis (p25-p75), empregado Teste de Wilcoxon. Resultados: 43 recém-nascidos, médias de peso 1883,5±580g e IG 32±2,4semanas, 23 (53%) receberam CPAPn como primeira modalidade ventilatória. Pré-termos após duas horas de VM apresentaram níveis significativamente maiores de IL-6, TNF-α e IL-8. Já os níveis de IL-6 reduziram significativamente após duas horas de CPAPn. Em 15 dos 22 (68%) neonatos cujas mães receberam corticoide pré-natal, as medianas das citocinas foram menores no início do uso do CPAPn, mas esse efeito não se sustentou duas horas após. O uso de surfactante pelos prematuros em VM não alterou a resposta inflamatória em comparação aos que não necessitaram do fármaco. Conclusão: demonstramos que os RN em CPAPn apresentaram mínima liberação de citocinas pro-inflamatórias e essa modalidade pode ter um papel protetor - nesse estudo potencializado pelo uso de corticoide ante natal. Por outro lado, VM promove significativa resposta inflamatória, estimulando-se CPAPn como estratégia ventilatória inicial protetora ao prematuro maior de 28 semanas de IG com desconforto respiratório moderado. Ainda assim, serão necessários mais estudos para determinar o papel de outras formas de ventilação não invasiva e outras formas de VM consideradas protetoras na prevenção da VILI. Essa nova compreensão dos mecanismos de lesão envolvendo resposta inflamatória mediada pelas citocinas possibilitará o desenvolvimento de novas estratégias no cuidado dos recém-nascidos prematuros. / The need for intubation and mechanical ventilation (MV) in preterm infants is related to ventilator-induced lung injury (VILI) and subsequent bronchopulmonary dysplasia (BPD). Studies in animals and in humans have shown that short periods of MV are enough for the release of pro-inflammatory interleukins. Other forms of MV that regulate tidal volume avoiding volutrauma and non- invasive ventilation such as continuous positive airway pressure by nasal prongs (nCPAP) seem protective measures against VILI. These protective effects of nCPAP have not been studied in humans. Objective: To evaluate the plasma levels of interleukin (IL) - 1β , IL - 6 , IL - 8 , IL - 10 and tumor necrosis factor (TNF) - α in preterm infants as soon as established nCPAP and two hours after. Secondarily, to evaluate this inflammatory response in patients who required MV. Methods: Prospective cohort including newborns admitted with gestational age (GA) of 28-35 weeks and requiring ventilation support, excluding malformations, congenital infections, sepsis, previous surfactant use and ventilatory support need in the delivery room. Blood samples were collected at those two moments. Cytokines were described as medians and interquartile ranges (p25 - p75), and Wilcoxon test was performed. Results: 43 newborns, medium weight 1883.5 ± 580g and gestational age of 32 ± 2.4 weeks, 23 (53 %) received nCPAP as the first ventilatory mode. Preterm two hours after MV had significantly higher levels of IL - 6, TNF - α and IL - 8. The levels of IL - 6 decreased significantly two hours after nCPAP. In 15 of 22 (68 %) neonates whose mothers received antenatal corticosteroids, the median of cytokines were lower at the onset of the nCPAP, but this effect was not sustained after two hours. The use of surfactant in preterm infants in MV did not alter the inflammatory response compared to those who did not need the drug. Conclusion: we demonstrated that nCPAP presents minimal release of pro-inflammatory cytokines and may have a protective role - in this study enhanced by the use of antenatal corticosteroids. Still, MV promotes significant inflammatory response, thus stimulating nCPAP as initial less harmful ventilatory strategy to preterm greater than 28 weeks of GA with moderate respiratory discomfort. Therefore, further studies are needed to determine the role of other forms of non-invasive ventilation and other forms of MV considered protective in preventing VILI. This new understanding of injury mechanisms involving inflammatory response mediated by cytokines allows the development of new strategies in the care of premature infants.

A necessidade de intubação e uso de ventilação mecânica (VM) na prematuridade está relacionada à chamada lesão pulmonar induzida pela ventilação (VILI) e consequente displasia broncopulmonar (DBP). Estudos com animais e também em humanos mostraram que breves períodos de VM são suficientes para a liberação de interleucinas pró-inflamatórias. Outras formas de VM que regulam o volume-corrente evitando o volutrauma e as ventilações não invasivas como a pressão positiva contínua em via aérea por pronga nasal (CPAPn) parecem medidas protetoras ou menos lesivas para VILI. Esses efeitos protetores do CPAPn não foram ainda estudados em humanos. Objetivo: avaliar os níveis plasmáticos da interleucina (IL)-1β, IL-6, IL-8, IL-10 e fator de necrose tumoral (TNF)-α em recém-nascidos tão logo instituído CPAPn e duas horas após. Secundariamente, avaliação dessa resposta inflamatória em pacientes que necessitaram de VM. Metodologia: estudo de coorte prospectivo, incluindo recém-nascidos admitidos com idade gestacional (IG) de 28-35 semanas e necessidade de assistência ventilatória, excluindo malformações, infecção congênita, sepse, surfactante profilático e suporte ventilatório em sala de parto. Amostras de sangue coletadas nesses dois momentos. Realizada descrição das variáveis em medianas e interquartis (p25-p75), empregado Teste de Wilcoxon. Resultados: 43 recém-nascidos, médias de peso 1883,5±580g e IG 32±2,4semanas, 23 (53%) receberam CPAPn como primeira modalidade ventilatória. Pré-termos após duas horas de VM apresentaram níveis significativamente maiores de IL-6, TNF-α e IL-8. Já os níveis de IL-6 reduziram significativamente após duas horas de CPAPn. Em 15 dos 22 (68%) neonatos cujas mães receberam corticoide pré-natal, as medianas das citocinas foram menores no início do uso do CPAPn, mas esse efeito não se sustentou duas horas após. O uso de surfactante pelos prematuros em VM não alterou a resposta inflamatória em comparação aos que não necessitaram do fármaco. Conclusão: demonstramos que os RN em CPAPn apresentaram mínima liberação de citocinas pro-inflamatórias e essa modalidade pode ter um papel protetor - nesse estudo potencializado pelo uso de corticoide ante natal. Por outro lado, VM promove significativa resposta inflamatória, estimulando-se CPAPn como estratégia ventilatória inicial protetora ao prematuro maior de 28 semanas de IG com desconforto respiratório moderado. Ainda assim, serão necessários mais estudos para determinar o papel de outras formas de ventilação não invasiva e outras formas de VM consideradas protetoras na prevenção da VILI. Essa nova compreensão dos mecanismos de lesão envolvendo resposta inflamatória mediada pelas citocinas possibilitará o desenvolvimento de novas estratégias no cuidado dos recém-nascidos prematuros. / The need for intubation and mechanical ventilation (MV) in preterm infants is related to ventilator-induced lung injury (VILI) and subsequent bronchopulmonary dysplasia (BPD). Studies in animals and in humans have shown that short periods of MV are enough for the release of pro-inflammatory interleukins. Other forms of MV that regulate tidal volume avoiding volutrauma and non- invasive ventilation such as continuous positive airway pressure by nasal prongs (nCPAP) seem protective measures against VILI. These protective effects of nCPAP have not been studied in humans. Objective: To evaluate the plasma levels of interleukin (IL) - 1β , IL - 6 , IL - 8 , IL - 10 and tumor necrosis factor (TNF) - α in preterm infants as soon as established nCPAP and two hours after. Secondarily, to evaluate this inflammatory response in patients who required MV. Methods: Prospective cohort including newborns admitted with gestational age (GA) of 28-35 weeks and requiring ventilation support, excluding malformations, congenital infections, sepsis, previous surfactant use and ventilatory support need in the delivery room. Blood samples were collected at those two moments. Cytokines were described as medians and interquartile ranges (p25 - p75), and Wilcoxon test was performed. Results: 43 newborns, medium weight 1883.5 ± 580g and gestational age of 32 ± 2.4 weeks, 23 (53 %) received nCPAP as the first ventilatory mode. Preterm two hours after MV had significantly higher levels of IL - 6, TNF - α and IL - 8. The levels of IL - 6 decreased significantly two hours after nCPAP. In 15 of 22 (68 %) neonates whose mothers received antenatal corticosteroids, the median of cytokines were lower at the onset of the nCPAP, but this effect was not sustained after two hours. The use of surfactant in preterm infants in MV did not alter the inflammatory response compared to those who did not need the drug. Conclusion: we demonstrated that nCPAP presents minimal release of pro-inflammatory cytokines and may have a protective role - in this study enhanced by the use of antenatal corticosteroids. Still, MV promotes significant inflammatory response, thus stimulating nCPAP as initial less harmful ventilatory strategy to preterm greater than 28 weeks of GA with moderate respiratory discomfort. Therefore, further studies are needed to determine the role of other forms of non-invasive ventilation and other forms of MV considered protective in preventing VILI. This new understanding of injury mechanisms involving inflammatory response mediated by cytokines allows the development of new strategies in the care of premature infants.

A necessidade de intubação e uso de ventilação mecânica (VM) na prematuridade está relacionada à chamada lesão pulmonar induzida pela ventilação (VILI) e consequente displasia broncopulmonar (DBP). Estudos com animais e também em humanos mostraram que breves períodos de VM são suficientes para a liberação de interleucinas pró-inflamatórias. Outras formas de VM que regulam o volume-corrente evitando o volutrauma e as ventilações não invasivas como a pressão positiva contínua em via aérea por pronga nasal (CPAPn) parecem medidas protetoras ou menos lesivas para VILI. Esses efeitos protetores do CPAPn não foram ainda estudados em humanos. Objetivo: avaliar os níveis plasmáticos da interleucina (IL)-1β, IL-6, IL-8, IL-10 e fator de necrose tumoral (TNF)-α em recém-nascidos tão logo instituído CPAPn e duas horas após. Secundariamente, avaliação dessa resposta inflamatória em pacientes que necessitaram de VM. Metodologia: estudo de coorte prospectivo, incluindo recém-nascidos admitidos com idade gestacional (IG) de 28-35 semanas e necessidade de assistência ventilatória, excluindo malformações, infecção congênita, sepse, surfactante profilático e suporte ventilatório em sala de parto. Amostras de sangue coletadas nesses dois momentos. Realizada descrição das variáveis em medianas e interquartis (p25-p75), empregado Teste de Wilcoxon. Resultados: 43 recém-nascidos, médias de peso 1883,5±580g e IG 32±2,4semanas, 23 (53%) receberam CPAPn como primeira modalidade ventilatória. Pré-termos após duas horas de VM apresentaram níveis significativamente maiores de IL-6, TNF-α e IL-8. Já os níveis de IL-6 reduziram significativamente após duas horas de CPAPn. Em 15 dos 22 (68%) neonatos cujas mães receberam corticoide pré-natal, as medianas das citocinas foram menores no início do uso do CPAPn, mas esse efeito não se sustentou duas horas após. O uso de surfactante pelos prematuros em VM não alterou a resposta inflamatória em comparação aos que não necessitaram do fármaco. Conclusão: demonstramos que os RN em CPAPn apresentaram mínima liberação de citocinas pro-inflamatórias e essa modalidade pode ter um papel protetor - nesse estudo potencializado pelo uso de corticoide ante natal. Por outro lado, VM promove significativa resposta inflamatória, estimulando-se CPAPn como estratégia ventilatória inicial protetora ao prematuro maior de 28 semanas de IG com desconforto respiratório moderado. Ainda assim, serão necessários mais estudos para determinar o papel de outras formas de ventilação não invasiva e outras formas de VM consideradas protetoras na prevenção da VILI. Essa nova compreensão dos mecanismos de lesão envolvendo resposta inflamatória mediada pelas citocinas possibilitará o desenvolvimento de novas estratégias no cuidado dos recém-nascidos prematuros. / The need for intubation and mechanical ventilation (MV) in preterm infants is related to ventilator-induced lung injury (VILI) and subsequent bronchopulmonary dysplasia (BPD). Studies in animals and in humans have shown that short periods of MV are enough for the release of pro-inflammatory interleukins. Other forms of MV that regulate tidal volume avoiding volutrauma and non- invasive ventilation such as continuous positive airway pressure by nasal prongs (nCPAP) seem protective measures against VILI. These protective effects of nCPAP have not been studied in humans. Objective: To evaluate the plasma levels of interleukin (IL) - 1β , IL - 6 , IL - 8 , IL - 10 and tumor necrosis factor (TNF) - α in preterm infants as soon as established nCPAP and two hours after. Secondarily, to evaluate this inflammatory response in patients who required MV. Methods: Prospective cohort including newborns admitted with gestational age (GA) of 28-35 weeks and requiring ventilation support, excluding malformations, congenital infections, sepsis, previous surfactant use and ventilatory support need in the delivery room. Blood samples were collected at those two moments. Cytokines were described as medians and interquartile ranges (p25 - p75), and Wilcoxon test was performed. Results: 43 newborns, medium weight 1883.5 ± 580g and gestational age of 32 ± 2.4 weeks, 23 (53 %) received nCPAP as the first ventilatory mode. Preterm two hours after MV had significantly higher levels of IL - 6, TNF - α and IL - 8. The levels of IL - 6 decreased significantly two hours after nCPAP. In 15 of 22 (68 %) neonates whose mothers received antenatal corticosteroids, the median of cytokines were lower at the onset of the nCPAP, but this effect was not sustained after two hours. The use of surfactant in preterm infants in MV did not alter the inflammatory response compared to those who did not need the drug. Conclusion: we demonstrated that nCPAP presents minimal release of pro-inflammatory cytokines and may have a protective role - in this study enhanced by the use of antenatal corticosteroids. Still, MV promotes significant inflammatory response, thus stimulating nCPAP as initial less harmful ventilatory strategy to preterm greater than 28 weeks of GA with moderate respiratory discomfort. Therefore, further studies are needed to determine the role of other forms of non-invasive ventilation and other forms of MV considered protective in preventing VILI. This new understanding of injury mechanisms involving inflammatory response mediated by cytokines allows the development of new strategies in the care of premature infants.

Une croissance intra-utérine insuffisante représente, avec la prématurité et les malfor-mations congénitales, une des principales causes de morbidité et de mortalité néonatales. Ces pathologies sont liées entre elles, les nouveau-nés prématurés étant souvent atteints de RCIU (RCIU). Les études épidémiologiques récentes ont montré que le RCIU était associé à une augmentation de la morbidité respiratoire dès la période néonatale, avec, en particulier, une augmentation du risque de dysplasie broncho-pulmonaire (DBP), principale séquelle respira-toire de la prématurité. La DBP est caractérisée par des anomalies du développement alvéo-laire et vasculaire, considérées comme les conséquences d’agressions multiples sur un poumon immature. La physiopathologie exacte reste encore largement méconnue. Nous nous sommes intéressés dans ce travail au lien entre RCIU et DBP avec un abord expérimental et clinique. Alors que les études épidémiologiques sont relativement concordantes sur le lien entre RCIU et DBP, les études expérimentales, montrent des résultats divers tant sur le développement pulmonaire qu’au niveau moléculaire. Nous avons donc voulu identifier, dans un premier temps, un modèle de RCIU reproduisant les anomalies du développement alvéolaire observées chez l’Homme en utilisant trois modèles précédemment validés chez le rat : un modèle de res-triction protidique per-gestationnelle , un modèle de ligature unilatérale de l’artère utérine, un modèle d’injection d’un inhibiteur chimique de la NO synthase, le L NAME. Seule la restric-tion protidique anténatale permet de reproduire à long terme des lésions de l’alvéolisation proches de celles observées dans la DBP. En revanche, dans ce modèle, les modifications des principaux gènes identifiés précédemment dans les anomalies le développement alvéolaire ne sont pas observées, que ce soit avant, pendant ou après l’alvéolisation. Ce résultat nous a ame-né à entreprendre une étude multigénique qui a permis d’identifier plusieurs voies modifiées pendant l’alvéolisation dans ce modèle. Parmi celles-ci, les gènes impliqués dans la contractili-té et l’adhésion cellulaire, l’immunité ou la voie des « Peroxisome Proliferator-Activated Re-ceptor ». Dans la partie clinique de cette étude, nous avons évalué le risque de DBP chez les extrêmes prématurés atteints de RCIU dont les mères présentaient des signes de pathologie vasculaire de la grossesse (prééclampsie). Cette étude rétrospective unicentrique sur 184 en-fants a permis de comparer des enfants atteints de RCIU à des enfants eutrophes pris en charge de manière homogène. Le RCIU d’origine vasculaire multiplie le risque de DBP par 6. Un marqueur précoce de l’évolution vers une DBP est un taux de plaquettes bas à la naissance, évoquant le rôle d’un taux élevé de facteurs anti-angiogéniques circulants. Une étude est en cours pour corréler les facteurs anti-angiogéniques circulants présents chez les mères pré-éclamptiques au devenir respiratoire, en particulier à l’évolution vers une DBP, de leurs nou-veau-nés d’âge gestationnel inférieur à 30 semaines d’aménorrhée. En conclusion, nous avons montré expérimentalement que seule la restriction protidique anténatale chez le rat reproduisait les troubles de l’alvéolisation comparables à ceux observés dans la DBP. De nouvelles voies moléculaires potentiellement impliquées dans les anomalies de l’alvéolisation ont été mises en évidence. Par ailleurs, le rôle de facteurs anti-angiogéniques d’origine maternelle comme fac-teurs de développement d’une DBP est en cours d’évaluation. / Insufficient intrauterine growth is with prematurity and congenital malformations, a major cause of neonatal morbidity and mortality. These conditions are interrelated, the preterm infants often suffered of intrauterine growth restriction (IUGR). Recent epidemiological stud-ies showed that IUGR was associated with increased respiratory morbidity as soon as the ne-onatal period, with an increased risk of bronchopulmonary dysplasia (BPD), the main respira-tory sequelae of prematurity. BPD is characterized by impaired alveolar and vascular devel-opment and is the consequence of multiple insults on an immature lung. The exact pathophysi-ology is still largely unknown. We study in this work the relationship between IUGR and DBP with an experimental and clinical approach. While epidemiological studies are relatively concordant on the relationship between IUGR and BPD, experimental studies showed various results in lung development and molecular process. We wanted to identify, at first, a model of IUGR reproducing impaired alveolar development observed in humans using three previously validated models in rats: a model of per-gestational protein restriction, a model of unilateral ligation uterine artery, an injection pattern of a chemical inhibitor of NO synthase, L NAME. Only antenatal protein restriction can reproduce long-term impaired alveolarization as those observed in BPD. However, in this model, changes in key genes previously identified in pathological alveolar development are not observed before, during or after alveolarization. This result led us to perform a genome-wide analysis which identified several modified path-ways during alveolarization. Among these, the genes involved in the “cardiac contractility”, “cell adhesion molecules”, “immunity”, “molecular adhesion” or the "Peroxisome Proliferator-Activated Receptor" pathways. In the clinical part of this study, we evaluated the risk of BPD in extreme preterm infants with IUGR whose mothers had evidence of vascular disease of pregnancy (preeclampsia). This single-center retrospective study of 184 children was used to compare children with IUGR in adjusted for gestational age children. The vascular IUGR increases the risk of DBP by 6. An early marker of progression to BPD is a low platelet count at birth, referring to the role of high levels of circulating anti-angiogenic factors. A study is ongoing to correlate circulating anti-angiogenic factors present in preeclamptic mothers to res-piratory outcome and particularly BDP, in newborn younger than 30 weeks of gestational age at birth. In conclusion, we have shown experimentally that only prenatal protein restriction in rats reproduced impaired alveolarization comparable to those observed in the BPD. New mo-lecular pathways potentially involved in the impaired alveolarization were highlighted. More-over, the role of placental anti-angiogenic factors leading to development of BPD is evaluat-ed.