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Kuper-Sassé ME, MacFarlane PM, Mayer CA, Martin RJ, Prakash YS, Pabelick CM, Raffay TM. Prenatal Maternal Lipopolysaccharide and Mild Newborn Hyperoxia Increase Intrapulmonary Airway but Not Vessel Reactivity in a Mouse Model. CHILDREN-BASEL 2021; 8:children8030195. [PMID: 33807828 PMCID: PMC7998377 DOI: 10.3390/children8030195] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 02/26/2021] [Accepted: 03/02/2021] [Indexed: 11/29/2022]
Abstract
Maternal infection is a risk for preterm delivery. Preterm newborns often require supplemental oxygen to treat neonatal respiratory distress. Newborn hyperoxia exposure is associated with airway and vascular hyperreactivity, while the complications of maternal infection are variable. In a mouse model of prenatal maternal intraperitoneal lipopolysaccharide (LPS, embryonic day 18) with subsequent newborn hyperoxia (40% oxygen × 7 days) precision-cut living lung slices were used to measure intrapulmonary airway and vascular reactivity at 21 days of age. Hyperoxia increased airway reactivity to methacholine compared to room air controls. Prenatal maternal LPS did not alter airway reactivity in room air. Combined maternal LPS and hyperoxia exposures increased airway reactivity vs. controls, although maximal responses were diminished compared to hyperoxia alone. Vessel reactivity to serotonin did not significantly differ in hyperoxia or room air; however, prenatal maternal LPS appeared to attenuate vessel reactivity in room air. Following room air recovery, LPS with hyperoxia lungs displayed upregulated inflammatory and fibrosis genes compared to room air saline controls (TNFαR1, iNOS, and TGFβ). In this model, mild newborn hyperoxia increases airway but not vessel reactivity. Prenatal maternal LPS did not further increase hyperoxic airway reactivity. However, inflammatory genes remain upregulated weeks after recovery from maternal LPS and newborn hyperoxia exposures.
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Affiliation(s)
- Margaret E. Kuper-Sassé
- Department of Pediatrics, Case Western Reserve University, UH Rainbow Babies & Children’s Hospital, Cleveland, OH 44106, USA; (M.E.K.-S.); (P.M.M.); (C.A.M.); (R.J.M.)
| | - Peter M. MacFarlane
- Department of Pediatrics, Case Western Reserve University, UH Rainbow Babies & Children’s Hospital, Cleveland, OH 44106, USA; (M.E.K.-S.); (P.M.M.); (C.A.M.); (R.J.M.)
| | - Catherine A. Mayer
- Department of Pediatrics, Case Western Reserve University, UH Rainbow Babies & Children’s Hospital, Cleveland, OH 44106, USA; (M.E.K.-S.); (P.M.M.); (C.A.M.); (R.J.M.)
| | - Richard J. Martin
- Department of Pediatrics, Case Western Reserve University, UH Rainbow Babies & Children’s Hospital, Cleveland, OH 44106, USA; (M.E.K.-S.); (P.M.M.); (C.A.M.); (R.J.M.)
| | - Y. S. Prakash
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN 55905, USA; (Y.S.P.); (C.M.P.)
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA
| | - Christina M. Pabelick
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN 55905, USA; (Y.S.P.); (C.M.P.)
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA
| | - Thomas M. Raffay
- Department of Pediatrics, Case Western Reserve University, UH Rainbow Babies & Children’s Hospital, Cleveland, OH 44106, USA; (M.E.K.-S.); (P.M.M.); (C.A.M.); (R.J.M.)
- Correspondence: ; Tel.: +216-844-3387
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Visconti K, Senthamaraikannan P, Kemp MW, Saito M, Kramer BW, Newnham JP, Jobe AH, Kallapur SG. Extremely preterm fetal sheep lung responses to antenatal steroids and inflammation. Am J Obstet Gynecol 2018; 218:349.e1-349.e10. [PMID: 29274832 DOI: 10.1016/j.ajog.2017.12.207] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 11/27/2017] [Accepted: 12/14/2017] [Indexed: 11/25/2022]
Abstract
BACKGROUND The efficacy of antenatal steroids for fetal lung maturation in the periviable period is not fully understood. OBJECTIVE We sought to determine the lung maturational effects of antenatal steroids and inflammation in early gestation sheep fetuses, similar to the periviable period in human beings. STUDY DESIGN Date-mated ewes with singleton fetuses were randomly assigned to 1 of 4 treatment groups (n = 8/group): (1) maternal intramuscular injection of betamethasone; (2) intraamniotic lipopolysaccharide; (3) betamethasone + lipopolysaccharide; and (4) intraamniotic + intramuscular saline (controls). Fetuses were delivered surgically 48 hours later at 94 days' gestation (63% term gestation) for comprehensive evaluations of lung maturation, and lung and systemic inflammation. RESULTS Relative to controls, first, betamethasone increased the fetal lung air space to mesenchymal area ratio by 47% but did not increase the messenger RNAs for the surfactant proteins-B and -C that are important for surfactant function or increase the expression of pro-surfactant protein-C in the alveolar type II cells. Second, betamethasone increased expression of 1 of the 4 genes in surfactant lipid synthetic pathways. Third, betamethasone increased genes involved in epithelium sodium channel transport, but not sodium-potassium adenosine triphosphatase or Aquaporin 5. Fourth, lipopolysaccharide increased proinflammatory genes in the lung but did not effectively recruit activated inflammatory cells. Last, betamethasone incompletely suppressed lipopolysaccharide-induced lung inflammation. In the liver, betamethasone when given alone increased the expression of serum amyloid A3 and C-reactive protein messenger RNAs. CONCLUSION Compared the more mature 125-day gestation sheep, antenatal steroids do not induce pulmonary surfactants during the periviable period, indicating a different response.
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Hütten MC, Wolfs TGAM, Kramer BW. Can the preterm lung recover from perinatal stress? Mol Cell Pediatr 2016; 3:15. [PMID: 27075524 PMCID: PMC4830776 DOI: 10.1186/s40348-016-0043-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Accepted: 03/22/2016] [Indexed: 11/10/2022] Open
Abstract
After birth, adequate lung function is necessary for the successful adaptation of a preterm baby. Both prenatal and postnatal insults and therapeutic interventions have an immediate effect on lung function and gas exchange but also interfere with fetal and neonatal lung development. Prenatal insults like chorioamnionitis and prenatal interventions like maternal glucocorticosteroids interact but might also determine the preterm baby's lung response to postnatal interventions ("second hit") like supplementation of oxygen and drug therapy. We review current experimental and clinical findings on the influence of different perinatal factors on preterm lung development and discuss how well-established interventions in neonatal care might be adapted to attenuate postnatal lung injury.
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Affiliation(s)
- Matthias C Hütten
- Neonatology, Department of Pediatrics, Maastricht University Medical Center, Maastricht, Netherlands.,Neonatology, Department of Pediatrics, Aachen University Hospital, Aachen, Germany.,Neonatology, Department of Pediatrics, Würzburg University Hospital, Würzburg, Germany.,Faculty of Health, Medicine and Lifesciences, School for Oncology and Developmental Biology, Maastricht University, Maastricht, The Netherlands
| | - Tim G A M Wolfs
- Neonatology, Department of Pediatrics, Maastricht University Medical Center, Maastricht, Netherlands.,Faculty of Health, Medicine and Lifesciences, School for Oncology and Developmental Biology, Maastricht University, Maastricht, The Netherlands
| | - Boris W Kramer
- Neonatology, Department of Pediatrics, Maastricht University Medical Center, Maastricht, Netherlands. .,Faculty of Health, Medicine and Lifesciences, School for Oncology and Developmental Biology, Maastricht University, Maastricht, The Netherlands.
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Jobe AH. Animal Models, Learning Lessons to Prevent and Treat Neonatal Chronic Lung Disease. Front Med (Lausanne) 2015; 2:49. [PMID: 26301222 PMCID: PMC4528292 DOI: 10.3389/fmed.2015.00049] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 07/14/2015] [Indexed: 11/23/2022] Open
Abstract
Bronchopulmonary dysplasia (BPD) is a unique injury syndrome caused by prolonged injury and repair imposed on an immature and developing lung. The decreased septation and decreased microvascular development phenotype of BPD can be reproduced in newborn rodents with increased chronic oxygen exposure and in premature primates and sheep with oxygen and/or mechanical ventilation. The inflammation caused by oxidants, inflammatory agonists, and/or stretch injury from mechanical ventilation seems to promote the anatomic abnormalities. Multiple interventions targeted to specific inflammatory cells or pathways or targeted to decreasing ventilation-mediated injury can substantially prevent the anatomic changes associated with BPD in term rodents and in preterm sheep or primate models. Most of the anti-inflammatory therapies with benefit in animal models have not been tested clinically. None of the interventions that have been tested clinically are as effective as anticipated from the animal models. These inconsistencies in responses likely are explained by the antenatal differences in lung exposures of the developing animals relative to very preterm humans. The animals generally have normal lungs while the lungs of preterm infants are exposed variably to intrauterine inflammation, growth abnormalities, antenatal corticosteroids, and poorly understood effects from the causes of preterm delivery. The animal models have been essential for the definition of the mediators that can cause a BPD phenotype. These models will be necessary to develop and test future-targeted interventions to prevent and treat BPD.
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Affiliation(s)
- Alan H Jobe
- Division of Pulmonary Biology, Cincinnati Children's Hospital Medical Center, University of Cincinnati , Cincinnati, OH , USA
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Bieghs V, Vlassaks E, Custers A, van Gorp PJ, Gijbels MJ, Bast A, Bekers O, Zimmermann LJI, Lütjohann D, Voncken JW, Gavilanes AWD, Kramer BW, Shiri-Sverdlov R. Chorioamnionitis induced hepatic inflammation and disturbed lipid metabolism in fetal sheep. Pediatr Res 2010; 68:466-72. [PMID: 20717072 DOI: 10.1203/pdr.0b013e3181f70eeb] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Chorioamnionitis frequently induces a fetal inflammatory response syndrome (FIRS), characterized by an elevation of proinflammatory mediators and systemic inflammation. Although there is increasing evidence that inflammation and lipid metabolism influence each other, the effects of chorioamnionitis-induced FIRS on fetal lipid homeostasis are currently not known. Accordingly, we hypothesize that chorioamnionitis induces an inflammatory response in the fetal liver, consequently leading to metabolic disturbances. Chorioamnionitis was induced by intra-amniotic injection of 10 mg endotoxin (control) for 2 d or 2 wk before delivery. Saline injections were given to controls. The effect of chorioamnionitis on hepatic inflammation and metabolic parameters was analyzed in ovine fetuses at the GA of 125 d (normal GA = 150 d). We found that 2 d after the endotoxin injections, inflammatory markers were significantly higher compared with controls. In addition, lipid and glucose metabolism were disturbed in response to endotoxin. Moreover, the antioxidant state capacity was reduced, and hepatic damage was apparent. Two weeks after the endotoxin injections, the fetal livers were still inflamed and had higher glucose concentrations in the blood. In addition, the levels of markers for hepatic damage (alanine aminotransferase and aspartate aminotransferase) were increased. In conclusion, chorioamnionitis induces liver inflammation leading to metabolic disturbances in the fetus.
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Affiliation(s)
- Veerle Bieghs
- Department of Molecular Genetics and Pathology, Maastricht University, Maastricht 6200 MD, The Netherlands
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Abstract
AIMS to summarize present knowledge regarding the relation between oxidative stress and development of bronchopulmonary dysplasia (BPD). METHODS relevant literature searched at Pubmed and other sources. RESULTS Oxidative stress is generated in a number of conditions and by a number of causes such as inflammation and hyperoxia. Ontogenic aspects are discussed. Oxidative stress as physiological regulators, its relation to transcription factors and inflammation is summarized. The role of oxygen and antioxidant therapy and newborn resuscitation for development and prevention of BPD as well as new therapeutic modes especially the use of growth factors, gene therapy and stem cells, are briefly discussed. CONCLUSION oxidative stress and BPD are associated. A better understanding of this association is necessary in order to reduce the severity and the incidence of the condition.
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Affiliation(s)
- Ola Didrik Saugstad
- Department of Pediatric Research, Oslo University Hospital, Rikshospitalet, University of Oslo, Norway.
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Tang JR, Seedorf GJ, Muehlethaler V, Walker DL, Markham NE, Balasubramaniam V, Abman SH. Moderate postnatal hyperoxia accelerates lung growth and attenuates pulmonary hypertension in infant rats after exposure to intra-amniotic endotoxin. Am J Physiol Lung Cell Mol Physiol 2010; 299:L735-48. [PMID: 20709730 DOI: 10.1152/ajplung.00153.2010] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
To determine the separate and interactive effects of fetal inflammation and neonatal hyperoxia on the developing lung, we hypothesized that: 1) antenatal endotoxin (ETX) causes sustained abnormalities of infant lung structure; and 2) postnatal hyperoxia augments the adverse effects of antenatal ETX on infant lung growth. Escherichia coli ETX or saline (SA) was injected into amniotic sacs in pregnant Sprague-Dawley rats at 20 days of gestation. Pups were delivered 2 days later and raised in room air (RA) or moderate hyperoxia (O₂, 80% O₂ at Denver's altitude, ∼65% O₂ at sea level) from birth through 14 days of age. Heart and lung tissues were harvested for measurements. Intra-amniotic ETX caused right ventricular hypertrophy (RVH) and decreased lung vascular endothelial growth factor (VEGF) and VEGF receptor-2 (VEGFR-2) protein contents at birth. In ETX-exposed rats (ETX-RA), alveolarization and vessel density were decreased, pulmonary vascular wall thickness percentage was increased, and RVH was persistent throughout the study period compared with controls (SA-RA). After antenatal ETX, moderate hyperoxia increased lung VEGF and VEGFR-2 protein contents in ETX-O₂ rats and improved their alveolar and vascular structure and RVH compared with ETX-RA rats. In contrast, severe hyperoxia (≥95% O₂ at Denver's altitude) further reduced lung vessel density after intra-amniotic ETX exposure. We conclude that intra-amniotic ETX induces fetal pulmonary hypertension and causes persistent abnormalities of lung structure with sustained pulmonary hypertension in infant rats. Moreover, moderate postnatal hyperoxia after antenatal ETX restores lung growth and prevents pulmonary hypertension during infancy.
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Affiliation(s)
- Jen-Ruey Tang
- Dept. of Pediatrics, Univ. of Colorado Health Sciences Center, Aurora, CO 80045, USA.
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Jobe AH, Kallapur SG. Long term consequences of oxygen therapy in the neonatal period. Semin Fetal Neonatal Med 2010; 15:230-5. [PMID: 20452844 PMCID: PMC2910185 DOI: 10.1016/j.siny.2010.03.007] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Preterm and term infants are frequently exposed to high concentrations of oxygen for prolonged periods. In experimental models, high and prolonged oxygen exposures cause delayed alveolar septation and a bronchopulmonary dysplasia phenotype. Often, however, the oxygen exposure is tolerated in that the infants recover without severe lung or systemic injury. Multiple exposures change oxygen sensitivity in adult and newborn animals. Examples are antenatal corticosteroids, inflammatory mediators or preconditioning with oxygen, which will increase tolerance to oxygen injury. Intrauterine growth restriction or postnatal nutritional deficits will increase oxygen injury. Different infants probably have quite variable sensitivities to oxygen injury, but there are no biomarkers available to predict the risk of oxygen injury.
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Affiliation(s)
- Alan H. Jobe
- Corresponding author. Address: Cincinnati Children's Hospital, Division of Pulmonary Biology, University of Cincinnati, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, USA. Tel.: +1 (513) 636-8563; fax: +1 (513) 636-8691. (A.H. Jobe)
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Cheah FC, Pillow JJ, Kramer BW, Polglase GR, Nitsos I, Newnham JP, Jobe AH, Kallapur SG. Airway inflammatory cell responses to intra-amniotic lipopolysaccharide in a sheep model of chorioamnionitis. Am J Physiol Lung Cell Mol Physiol 2008; 296:L384-93. [PMID: 19118089 DOI: 10.1152/ajplung.90547.2008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Chorioamnionitis, a risk factor for bronchopulmonary dysplasia in preterm infants, causes an influx of inflammatory cells into the fetal lung. Using a fetal sheep model, we evaluated the time course of activation, functional maturity, and apoptosis of the leukocytes recruited to the fetal air spaces by lipopolysaccharide (LPS). Time-mated sheep were given intra-amniotic injections with 10 mg of Escherichia coli LPS or saline 2 or 7 days before preterm delivery at 124 days of gestation (term is 150 days). Both neutrophils and monocytes in bronchoalveolar lavage fluid (BALF) had activated NF-kappaB after 2- and 7-day LPS exposures. These neutrophils and monocytes expressed the activation factor CD11b and the maturation factor PU.1 at 2 days, and increased PU.1 expression was detected in macrophages at 7 days. Leukocyte oxidative burst activity was greatest at 7 days. BALF lipid peroxidation increased fivefold at 2 days, while protein carbonyls increased eightfold at 7 days. Nitrative stress was not detected in the BALF, but leukocytes in the lung expressed nitric oxide synthase (NOS)II (inducible NOS). BALF leukocytes expressed the antioxidant peroxiredoxin V. Lung glutathione peroxidase was also increased with LPS exposure. There was minimal apoptosis of airway and lung leukocytes assessed by caspase-3 activation. Intra-amniotic LPS recruits leukocytes to the fetal air space that have a persistent activation. These results have implications for the pathogenesis of lung inflammatory disorders in the preterm.
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Affiliation(s)
- Fook-Choe Cheah
- Division of Pulmonary Biology, Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio 45229-3039, USA
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Cheah FC, Jobe AH, Moss TJ, Newnham JP, Kallapur SG. Oxidative stress in fetal lambs exposed to intra-amniotic endotoxin in a chorioamnionitis model. Pediatr Res 2008; 63:274-9. [PMID: 18091343 DOI: 10.1203/pdr.0b013e31815f653b] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Chorioamnionitis is a risk factor for the development of bronchopulmonary dysplasia. Endotoxin-induced oxidative stress to the fetus in the uniquely hypoxic intrauterine environment has not been reported. Using a model of chorioamnionitis, we measured markers of pulmonary and systemic oxidant exposures in fetal lambs at 124 d gestation (term = 150 d) exposed to 10 mg intra-amniotic endotoxin 2 d (n = 6) or 7 d (n = 6) before delivery, or saline as controls (n = 9). The 7 d endotoxin-exposed animals had 3-fold higher protein carbonyls (0.66 +/- 0.46 versus 0.23 +/- 0.14 nmol/mg protein) and 10-fold greater myeloperoxidase activity (2.38 +/- 1.87 versus 0.27 +/- 0.18 nM) in the bronchoalveolar lavage fluid (BALF), suggestive of neutrophil-derived oxidant activity. However, in the lung tissue, protein carbonyls, superoxide dismutase, and peroxiredoxin 1 were not different between groups. The expression of peroxiredoxin 1 was prominent, primarily in the peri-bronchiolar epithelium. Notably, evidence of oxidant exposure was minimal at 2 d when BALF inflammatory cells, lung IL-1beta, and IL-8 were highest. Intra-amniotic endotoxin induced systemic oxidative stress as plasma protein carbonyl was elevated at 7 d (0.14 +/- 0.04 nmol/mg protein; p = 0.005). Surfactant protein A and B mRNAs were highest at 2 d, suggesting that oxidative stress did not contribute to the lung maturation response. A modest lung oxidative stress in chorioamnionitis could contribute to bronchopulmonary dysplasia.
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Affiliation(s)
- Fook-Choe Cheah
- Department of Neonatology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.
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Abstract
PURPOSE This study was undertaken to determine the effects of intratracheal administration of endotoxin on hyperoxia-induced lung injury in neonatal rats. MATERIALS AND METHODS Newborn Sprague Dawley rat pups were divided into four experimental groups: normoxia control (NC), normoxia with endotoxin treatment (NE), hyperoxia control (HC), and hyperoxia with endotoxin treatment (HE) groups. In HC and HE, rat pups were subjected to 14 days of hyperoxia (> 95% oxygen) within 12 hours after birth. In endotoxin treated group (NE and HE), Escherichia coli endotoxin (0.5microg in 0.03mL of saline) was given intratracheally at the 1st, 3rd and 5th postnatal day. Radial alveolar count (RAC), mean linear intercept (MLI), RAC/MLI ratios, and degree of fibrosis were measured to assess the changes in lung morphology. RESULTS During the research period, survival rates in both HC and HE were notably reduced 7 days after endotoxin was administered, but body weight gain was considerably reduced only in HC. On day 14, significant arrest in alveolarization, as evidenced by the decrease of RAC and RAC/MLI ratio and increase of MLI as well as increased fibrosis, were noted in HC. Although slight but significant arrest in alveolarization and increased fibrosis score were observed in NE compared to NC, the hyperoxia-induced lung damage observed in HC was significantly improved in HE. CONCLUSION This study suggests that intratracheal administration of endotoxin significantly attenuated hyperoxia-induced lung injury in neonatal rats.
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Affiliation(s)
- Jae Won Shim
- Department of Pediatrics, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Yun Sil Chang
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Won Soon Park
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
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Sweet DG, Huggett MT, Warner JA, Moss TJM, Kloosterboer N, Halliday HL, Newnham JP, Kallapur SG, Jobe AH, Kramer BW. Maternal betamethasone and chorioamnionitis induce different collagenases during lung maturation in fetal sheep. Neonatology 2008; 94:79-86. [PMID: 18264025 DOI: 10.1159/000115949] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2007] [Accepted: 10/29/2007] [Indexed: 11/19/2022]
Abstract
BACKGROUND Fetal lung maturation occurs after both maternal corticosteroid administration and chorioamnionitis. The effectors of this antenatally-induced lung maturation are not understood. Matrix metalloproteinases (MMPs) 2 and 9 are type-IV collagenases that can degrade alveolar basement membranes. OBJECTIVES We hypothesized that the structural changes of lung maturation by both antenatal corticosteroid treatment and chorioamnionitis would be associated with increases in these MMPs. METHODS 64 pregnant ewes were randomly assigned to one of four treatment groups: intra-amniotic injection of 10 mg endotoxin, maternal intramuscular injection of 0.5 mg/kg betamethasone, both treatments combined or saline-treated controls. We quantified MMP-2 which is derived from connective tissue and MMP-9 which is predominantly derived from neutrophils in fetal lung fluid of lambs after maternal corticosteroid therapy and induction of chorioamnionitis and the combination of both therapies given at 109-111 days' gestational age with delivery 1, 5 or 15 days later. RESULTS Betamethasone, endotoxin and the combined treatments increased both surfactant pool size, lung gas volume and reduced alveolar wall thickness at 15 days. MMP-2 concentration was increased after betamethasone. MMP-9 concentration increased after endotoxin-induced chorioamnionitis but decreased by the combined treatments. CONCLUSION Lung maturation via different pathways may use different forms of collagenases for remodelling lung structure.
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Affiliation(s)
- David G Sweet
- Department of Child Health, The Queen's University of Belfast, UK
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Sosenko IRS, Kallapur SG, Nitsos I, Moss TJM, Newnham JP, Ikegami M, Jobe AH. IL-1 alpha causes lung inflammation and maturation by direct effects on preterm fetal lamb lungs. Pediatr Res 2006; 60:294-8. [PMID: 16857758 DOI: 10.1203/01.pdr.0000233115.51309.d3] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Intra-amniotic endotoxin induces IL-1, causes chorioamnionitis, lung inflammation, lung injury and lung maturation in preterm lambs. Intra-amniotic IL-1alpha also causes chorioamnionitis, lung inflammation and lung maturation. We asked if IL-1alpha effects on the preterm lung are mediated by direct signaling to the lung rather than by indirect effects from the chorioamnionitis. To study IL-1 effects independently of chorioamnionitis, the lungs and the amniotic fluid were surgically separated in fetal sheep by diverting fetal lung fluid via a tracheostomy tube to a sialastic bag. A mini-osmotic pump delivered an intratracheal infusion of recombinant sheep IL-1alpha (10 microg) or saline (control) over 24 h. Preterm lambs were delivered 1d or 7d after the start of the infusion at 124d gestational age (Term = 150d). IL-1alpha recruited inflammatory cells and increased pro-inflammatory cytokine mRNA expression in the fetal lungs. Compared with controls, IL-1alpha did not alter lung antioxidant enzyme activity or alveolar numbers. IL-1alpha had minimal effects on the mRNA or protein expression of proteins essential for vascular development. IL-1alpha induced large increases in alveolar surfactant saturated phosphatidylcholine and increased lung gas volumes. Lung inflammation and maturation result from direct exposure of the fetal lung to a single cytokine - IL-1alpha.
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Affiliation(s)
- Ilene R S Sosenko
- Department of Pediatrics, University of Miami School of Medicine, Miami, FL 33106, USA
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Kallapur SG, Nitsos I, Moss TJM, Kramer BW, Newnham JP, Ikegami M, Jobe AH. Chronic endotoxin exposure does not cause sustained structural abnormalities in the fetal sheep lungs. Am J Physiol Lung Cell Mol Physiol 2005; 288:L966-74. [PMID: 15640284 DOI: 10.1152/ajplung.00389.2004] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Chronic early gestational chorioamnionitis is associated with development of bronchopulmonary dysplasia in preterm infants. A single intra-amniotic exposure to endotoxin decreased alveolarization and reduced expression of endothelial proteins in 125-day gestational age preterm lambs. We hypothesized that prolonged exposure to intra-amniotic endotoxin would cause progressive lung inflammation and inhibit alveolar and pulmonary vascular development. Endotoxin (1 mg/day) or saline was administered via an intra-amniotic osmotic pump from 80 to 108 days of gestational age (continuous pump) or by four weekly 10-mg intra-amniotic endotoxin injections starting at 100 days of gestational age (multiple dose). Lung morphometry, lung inflammation, vascular effects, and lung maturation were measured at delivery. The continuous pump lambs delivered at 100 days (approximately 70% of total endotoxin exposure) had lung inflammation, fewer saccules, and decreased endothelial proteins endothelial nitric oxide synthase and VEGF receptor 2 expression compared with controls. The continuous pump (delivered at 138 days) and multiple dose lambs (delivered at 130 and 145 days) had mild persistent lung inflammation and no significant differences in lung morphometry or expression of endothelial proteins compared with controls. Surfactant saturated phosphatidylcholine pool sizes were increased in all endotoxin-exposed groups, but lung function was not changed relative to controls. Contrary to our hypothesis, a prolonged fetal exposure to intra-amniotic endotoxin caused mild persistent inflammation but did not lead to progressive structural abnormalities in lungs of near-term gestation lambs.
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Affiliation(s)
- Suhas G Kallapur
- Cincinnati Children's Hospital Medical Center, Div. of Pulmonary Biology, University of Cincinnati College of Medicine, OH 45229-3039, USA.
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