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Britt RD, Faksh A, Vogel E, Martin RJ, Pabelick CM, Prakash YS. Perinatal factors in neonatal and pediatric lung diseases. Expert Rev Respir Med 2013; 7:515-31. [PMID: 24090092 DOI: 10.1586/17476348.2013.838020] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Wheezing and asthma are significant clinical problems for infants and young children, particularly following premature birth. Recurrent wheezing in infants can progress to persistent asthma. As in adults, altered airway structure (remodeling) and function (increased bronchoconstriction) are also important in neonatal and pediatric airway diseases. Accumulating evidence suggests that airway disease in children is influenced by perinatal factors including perturbations in normal fetal lung development, postnatal interventions in the intensive care unit (ICU) and environmental and other insults in the neonatal period. Here, in addition to genetics, maternal health, environmental processes, innate immunity and impaired lung development/function can all influence pathogenesis of airway disease in children. We summarize current understanding of how prenatal and postnatal factors can contribute to development of airway diseases in neonates and children. Understanding these mechanisms will help identify and develop novel therapies for childhood airway diseases.
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Affiliation(s)
- Rodney D Britt
- Department of Physiology and Biomedical Engineering, 4-184 W Jos SMH, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA
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Galinsky R, Hooper SB, Polglase GR, Moss TJM. Intrauterine inflammation alters fetal cardiopulmonary and cerebral haemodynamics in sheep. J Physiol 2013; 591:5061-70. [PMID: 23878364 DOI: 10.1113/jphysiol.2013.259119] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Intrauterine inflammation impairs fetal pulmonary vascular development and increases cerebral metabolic rate in fetal sheep. We hypothesized that these structural and metabolic effects of intrauterine inflammation would be accompanied by reduced fetal pulmonary blood flow and increased cerebral perfusion. Fetal sheep were instrumented at 112 days of gestation (term is 147 days) for measurement of cardiopulmonary and cerebral haemodynamics. At 118 days ewes were randomly assigned to receive intra-amniotic lipopolysaccharide (LPS, 20 mg from Escherichia coli; n = 7) or saline (control, 4 ml; n = 6). Fetal haemodynamic data were recorded continually from 1 h before intra-amniotic LPS or saline, until 144 h after. Fetal arterial blood was sampled before, and periodically after, intra-amniotic LPS or saline. End-diastolic and mean pulmonary blood flows were significantly lower than control from 48 and 96 h after LPS exposure, respectively, until the end of the experiment. Carotid blood flow was transiently increased at 96 and 120 h after LPS exposure. Carotid arterial oxygen content was lower than control from 48 h after intra-amniotic LPS. Fetal arterial lactate concentration was higher than control between 4 and 12 h after intra-amniotic LPS. Experimental intrauterine inflammation reduces pulmonary blood flow in fetal sheep, over a time course consistent with impaired pulmonary vascular development. Increased carotid blood flow after LPS administration may reflect an inflammation-induced increase in cerebral metabolic demand.
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Affiliation(s)
- Robert Galinsky
- R. Galinsky: The Ritchie Centre, Monash Institute of Medical Research, PO Box 5418, Clayton, Victoria 3168, Australia.
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Hillman NH, Kemp MW, Noble PB, Kallapur SG, Jobe AH. Sustained inflation at birth did not protect preterm fetal sheep from lung injury. Am J Physiol Lung Cell Mol Physiol 2013; 305:L446-53. [PMID: 23873843 DOI: 10.1152/ajplung.00162.2013] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Sustained lung inflations (SI) at birth may recruit functional residual capacity (FRC). Clinically, SI increase oxygenation and decrease need for intubation in preterm infants. We tested whether a SI to recruit FRC would decrease lung injury from subsequent ventilation of fetal, preterm lambs. The preterm fetus (128±1 day gestation) was exteriorized from the uterus, a tracheostomy was performed, and fetal lung fluid was removed. While maintaining placental circulation, fetuses were randomized to one of four 15-min interventions: 1) positive end-expiratory pressure (PEEP) 8 cmH2O (n=4), 2) 20 s SI to 50 cmH2O then PEEP 8 cmH2O (n=10), 3) mechanical ventilation at tidal volume (VT) 7 ml/kg (n=13), or 4) 20 s SI then ventilation at VT 7 ml/kg (n=13). Lambs were ventilated with 95% N2/5% CO2 and PEEP 8 cmH2O. Volume recruitment was measured during SI, and fetal tissues were collected after an additional 30 min on placental support. SI achieved a mean FRC recruitment of 15 ml/kg (range 8-27). Fifty percent of final FRC was achieved by 2 s, 65% by 5 s, and 90% by 15 s, demonstrating prolonged SI times are needed to recruit FRC. SI alone released acute-phase proteins into the fetal lung fluid and increased mRNA expression of proinflammatory cytokines and acute-phase response genes in the lung. Mechanical ventilation further increased all markers of lung injury. SI before ventilation, regardless of the volume of FRC recruited, did not alter the acute-phase and proinflammatory responses to mechanical ventilation at birth.
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Affiliation(s)
- Noah H Hillman
- Saint Louis Univ., Cardinal Glennon-Neonatology, 1100 South Grand, Saint Louis, MO 63104.
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Kallapur SG, Presicce P, Senthamaraikannan P, Alvarez M, Tarantal AF, Miller LM, Jobe AH, Chougnet CA. Intra-amniotic IL-1β induces fetal inflammation in rhesus monkeys and alters the regulatory T cell/IL-17 balance. THE JOURNAL OF IMMUNOLOGY 2013; 191:1102-9. [PMID: 23794628 DOI: 10.4049/jimmunol.1300270] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Very low birth weight preterm newborns are susceptible to the development of debilitating inflammatory diseases, many of which are associated with chorioamnionitis. To define the effects of chorioamnionitis on the fetal immune system, IL-1β was administered intra-amniotically at ~80% gestation in rhesus monkeys. IL-1β caused histological chorioamnionitis, as well as lung inflammation (infiltration of neutrophils or monocytes in the fetal airways). There were large increases in multiple proinflammatory cytokine mRNAs in the lungs at 24 h postadministration, which remained elevated relative to controls at 72 h. Intra-amniotic IL-1β also induced the sustained expression of the surfactant proteins in the lungs. Importantly, IL-1β significantly altered the balance between inflammatory and regulatory T cells. Twenty-four hours after IL-1β injection, the frequency of CD3(+)CD4(+)FOXP3(+) T cells was decreased in lymphoid organs. In contrast, IL-17A-producing cells (CD3(+)CD4(+), CD3(+)CD4(-), and CD3(-)CD4(-) subsets) were increased in lymphoid organs. The frequency of IFN-γ-expressing cells did not change. In this model of a single exposure to an inflammatory trigger, CD3(+)CD4(+)FOXP3(+) cells rebounded quickly, and their frequency was increased at 72 h compared with controls. IL-17 expression was also transient. Interestingly, the T cell profile alteration was confined to the lymphoid organs and not to circulating fetal T cells. Together, these results suggest that the chorioamnionitis-induced IL-1/IL-17 axis is involved in the severe inflammation that can develop in preterm newborns. Boosting regulatory T cells and/or controlling IL-17 may provide a means to ameliorate these abnormalities.
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Affiliation(s)
- Suhas G Kallapur
- Perinatal Institute, Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, OH 45229, USA
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56
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Gisslen T, Hillman NH, Musk GC, Kemp MW, Kramer BW, Senthamaraikannan P, Newnham JP, Jobe AH, Kallapur SG. Repeated exposure to intra-amniotic LPS partially protects against adverse effects of intravenous LPS in preterm lambs. Innate Immun 2013; 20:214-24. [PMID: 23751819 DOI: 10.1177/1753425913488430] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Histologic chorioamnionitis, frequently associated with preterm births and adverse outcomes, results in prolonged exposure of preterm fetuses to infectious agents and pro-inflammatory mediators, such as LPS. Endotoxin tolerance-type effects were demonstrated in fetal sheep following repetitive systemic or intra-amniotic (i.a.) exposures to LPS, suggesting that i.a. LPS exposure would cause endotoxin tolerance to a postnatal systemic dose of LPS in preterm sheep. In this study, randomized pregnant ewes received either two i.a. injections of LPS or saline prior to preterm delivery. Following operative delivery, the lambs were treated with surfactant, ventilated, and randomized to receive either i.v. LPS or saline at 30 min of age. Physiologic variables and indicators of systemic and lung inflammation were measured. Intravenous LPS decreased blood neutrophils and platelets values following i.a. saline compared to that after i.a. LPS. Intra-amniotic LPS prevented blood pressure from decreasing following the i.v. LPS, but also caused an increased oxygen index. Intra-amniotic LPS did not cause endotoxin tolerance as assessed by cytokine expression in the liver, lung or plasma, but increased myeloperoxidase-positive cells in the lung. The different compartments of exposure to LPS (i.a. vs i.v.) are unique to the fetal to newborn transition. Intra-amniotic LPS incompletely tolerized fetal lambs to postnatal i.v. LPS.
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Affiliation(s)
- Tate Gisslen
- 1Division of Neonatology/Pulmonary Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
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Kunzmann S, Collins JJ, Kuypers E, Kramer BW. Thrown off balance: the effect of antenatal inflammation on the developing lung and immune system. Am J Obstet Gynecol 2013; 208:429-37. [PMID: 23313727 DOI: 10.1016/j.ajog.2013.01.008] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Revised: 12/24/2012] [Accepted: 01/04/2013] [Indexed: 12/15/2022]
Abstract
In recent years, translational research with various animal models has been helpful to answer basic questions about the effect of antenatal inflammation on maturation and development of the fetal lung and immune system. The fetal lung and immune systems are very plastic and their development can be conditioned and influenced by both endogenous and/or exogenous factors. Antenatal inflammation can induce pulmonary inflammation, leading to lung injury and remodeling in the fetal lung. Exposure to antenatal inflammation can induce interleukin-1α production, which enhances surfactant protein and lipid synthesis thereby promoting lung maturation. Interleukin-1α is therefore a candidate for the link between lung inflammation and lung maturation, preventing respiratory distress syndrome in preterm infants. Antenatal inflammation can, however, cause structural changes in the fetal lung and affect the expression of growth factors, such as transforming growth factor-beta, connective tissue growth factor, fibroblast growth factor-10, or bone morphogenetic protein-4, which are essential for branching morphogenesis. These alterations cause alveolar and microvascular simplification resembling the histology of bronchopulmonary dysplasia. Antenatal inflammation may also affect neonatal outcome by modulating the responsiveness of the immune system. Lipopolysaccharide-tolerance (endotoxin hyporesponsiveness/immunoparalysis), induced by exposure to inflammation in utero, may prevent fetal lung damage, but increases susceptibility to postnatal infections. Moreover, prenatal exposure to inflammation appears to be a predisposition for the development of adverse neonatal outcomes, like bronchopulmonary dysplasia, if the preterm infant is exposed to a second postnatal hit, such as mechanical ventilation oxygen exposure, infections, or steroids.
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Kemp MW, Kannan PS, Saito M, Newnham JP, Cox T, Jobe AH, Kramer BW, Kallapur SG. Selective exposure of the fetal lung and skin/amnion (but not gastro-intestinal tract) to LPS elicits acute systemic inflammation in fetal sheep. PLoS One 2013; 8:e63355. [PMID: 23691033 PMCID: PMC3656923 DOI: 10.1371/journal.pone.0063355] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Accepted: 03/31/2013] [Indexed: 01/25/2023] Open
Abstract
Inflammation of the uterine environment (commonly as a result of microbial colonisation of the fetal membranes, amniotic fluid and fetus) is strongly associated with preterm labour and birth. Both preterm birth and fetal inflammation are independently associated with elevated risks of subsequent short- and long-term respiratory, gastro-intestinal and neurological complications. Despite numerous clinical and experimental studies to investigate localised and systemic fetal inflammation following exposure to microbial agonists, there is minimal data to describe which fetal organ(s) drive systemic fetal inflammation. We used lipopolysaccharide (LPS) from E.coli in an instrumented ovine model of fetal inflammation and conducted a series of experiments to assess the systemic pro-inflammatory capacity of the three major fetal surfaces exposed to inflammatory mediators in pregnancy (the lung, gastro-intestinal tract and skin/amnion). Exposure of the fetal lung and fetal skin/amnion (but not gastro-intestinal tract) caused a significant acute systemic inflammatory response characterised by altered leucocytosis, neutrophilia, elevated plasma MCP-1 levels and inflammation of the fetal liver and spleen. These novel findings reveal differential fetal organ responses to pro-inflammatory stimulation and shed light on the pathogenesis of fetal systemic inflammation after exposure to chorioamnionitis.
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Affiliation(s)
- Matthew W. Kemp
- School of Women’s and Infants’ Health, The University of Western Australia, Perth, Australia
| | - Paranthaman Senthamarai Kannan
- Division of Pulmonary Biology, Cincinnati Children’s Hospital Medical Centre, University of Cincinnati School of Medicine, Cincinnati, Ohio, United States of America
| | - Masatoshi Saito
- School of Women’s and Infants’ Health, The University of Western Australia, Perth, Australia
- Division of Perinatal Medicine, Tohoku University Hospital, Sendai, Japan
| | - John P. Newnham
- School of Women’s and Infants’ Health, The University of Western Australia, Perth, Australia
| | - Tom Cox
- School of Women’s and Infants’ Health, The University of Western Australia, Perth, Australia
| | - Alan H. Jobe
- School of Women’s and Infants’ Health, The University of Western Australia, Perth, Australia
- Division of Pulmonary Biology, Cincinnati Children’s Hospital Medical Centre, University of Cincinnati School of Medicine, Cincinnati, Ohio, United States of America
| | - Boris W. Kramer
- School of Women’s and Infants’ Health, The University of Western Australia, Perth, Australia
- Department of Paediatrics, School of Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Suhas G. Kallapur
- School of Women’s and Infants’ Health, The University of Western Australia, Perth, Australia
- Division of Pulmonary Biology, Cincinnati Children’s Hospital Medical Centre, University of Cincinnati School of Medicine, Cincinnati, Ohio, United States of America
- * E-mail:
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Robinson JW, Dando SJ, Nitsos I, Newnham J, Polglase GR, Kallapur SG, Pillow JJ, Kramer BW, Jobe AH, Payton D, Knox CL. Ureaplasma parvum serovar 3 multiple banded antigen size variation after chronic intra-amniotic infection/colonization. PLoS One 2013; 8:e62746. [PMID: 23638142 PMCID: PMC3637154 DOI: 10.1371/journal.pone.0062746] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Accepted: 03/28/2013] [Indexed: 12/21/2022] Open
Abstract
Ureaplasma species are the microorganisms most frequently associated with adverse pregnancy outcomes. The multiple banded antigen (MBA), a surface-exposed lipoprotein, is a key virulence factor of ureaplasmas. The MBA demonstrates size variation, which we have shown previously to be correlated with the severity of chorioamnion inflammation. We aimed to investigate U. parvum serovar 3 pathogenesis in vivo, using a sheep model, by investigating: MBA variation after long term (chronic) and short term (acute) durations of in utero ureaplasma infections, and the severity of chorioamnionitis and inflammation in other fetal tissues. Inocula of 2×107 colony-forming-units (CFU) of U. parvum serovar 3 (Up) or media controls (C) were injected intra-amniotically into pregnant ewes at one of three time points: day 55 (69d Up, n = 8; C69, n = 4); day 117 (7d Up, n = 8; C7, n = 2); and day 121 (3d Up, n = 8; C3, n = 2) of gestation (term = 145–150d). At day 124, preterm fetuses were delivered surgically. Samples of chorioamnion, fetal lung, and umbilical cord were: (i) snap frozen for subsequent ureaplasma culture, and (ii) fixed, embedded, sectioned and stained by haematoxylin and eosin stain for histological analysis. Selected fetal lung clinical ureaplasma isolates were cloned and filtered to obtain cultures from a single CFU. Passage 1 and clone 2 ureaplasma cultures were tested by western blot to demonstrate MBA variation. In acute durations of ureaplasma infection no MBA variants (3d Up) or very few MBA variants (7d Up) were present when compared to the original inoculum. However, numerous MBA size variants were generated in vivo (alike within contiguous tissues, amniotic fluid and fetal lung, but different variants were present within chorioamnion), during chronic, 69d exposure to ureaplasma infection. For the first time we have shown that the degree of ureaplasma MBA variation in vivo increased with the duration of gestation.
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Affiliation(s)
- James W. Robinson
- Institute of Health & Biomedical Innovation, Faculty of Health, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Samantha J. Dando
- Institute of Health & Biomedical Innovation, Faculty of Health, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Ilias Nitsos
- School of Women’s and Infants’ Health, The University of Western Australia, Perth, Western Australia, Australia
| | - John Newnham
- School of Women’s and Infants’ Health, The University of Western Australia, Perth, Western Australia, Australia
| | - Graeme R. Polglase
- School of Women’s and Infants’ Health, The University of Western Australia, Perth, Western Australia, Australia
| | - Suhas G. Kallapur
- School of Women’s and Infants’ Health, The University of Western Australia, Perth, Western Australia, Australia
- Department of Neonatology and Pulmonary Biology, Cincinnati Children’s Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - J. Jane Pillow
- School of Anatomy, Physiology and Human Biology, University of Western Australia, Perth, Western Australia, Australia
| | - Boris W. Kramer
- Department of Pediatrics, School of Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Alan H. Jobe
- School of Women’s and Infants’ Health, The University of Western Australia, Perth, Western Australia, Australia
- Department of Neonatology and Pulmonary Biology, Cincinnati Children’s Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Diane Payton
- Pathology Queensland, Royal Brisbane and Women’s Hospital, Herston, Queensland, Australia
| | - Christine L. Knox
- Institute of Health & Biomedical Innovation, Faculty of Health, Queensland University of Technology, Brisbane, Queensland, Australia
- * E-mail:
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Westover AJ, Moss TJM. Effects of intrauterine infection or inflammation on fetal lung development. Clin Exp Pharmacol Physiol 2013; 39:824-30. [PMID: 22816773 DOI: 10.1111/j.1440-1681.2012.05742.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
1. Intrauterine infection or inflammation is common in cases of preterm birth. Preterm infants are at risk of acute respiratory distress as a result of lung immaturity; evidence of exposure to infection and/or inflammation before birth is associated with a reduced risk of neonatal respiratory distress syndrome (RDS). Experimentally induced intrauterine inflammation or infection in sheep causes a precocious increase in pulmonary surfactant in the preterm lungs that improves preterm lung function, consistent with the reduced risk of RDS in human infants exposed to infection and/or inflammation before birth. 2. The effects of intrauterine inflammation on fetal lung development appear to result from direct action of proinflammatory stimuli within the lungs rather than by systemic signals, such as the classical glucocorticoid-mediated lung maturation pathway. However, paracrine and/or autocrine production and/or metabolism of glucocorticoids in fetal lung tissue may occur as a result of inflammation-induced changes in the expression of 11β-hydroxysteroid dehydrogenase (types 1 and 2). 3. Likely candidates that mediate inflammation-induced surfactant production by the preterm lung include prostaglandin E₂ and/or other arachidonic acid metabolites. Intrauterine inflammation induces the expression of enzymes responsible for prostaglandin production in fetal lung tissue. Inhibition of prostaglandin production prevents, at least in part, the effects of inflammation on fetal lungs. 4. Our experiments are identifying mechanisms of surfactant production by the preterm lungs that may be exploited as novel therapies for preventing respiratory distress in preterm infants. Elucidation of the effects of inflammation on the fetal lungs and other organs will allow more refined approaches to the care of preterm infants exposed to inflammation in utero.
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Affiliation(s)
- Alana J Westover
- The Ritchie Centre, Monash Institute of Medical Research, Clayton, Victoria, Australia
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61
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Strackx E, Gantert M, Moers V, van Kooten IAJ, Rieke R, Hürter H, Lemmens MAM, Steinbusch HWM, Zimmermann LJI, Vles JSH, Garnier Y, Gavilanes AWD, Kramer BW. Increased number of cerebellar granule cells and astrocytes in the internal granule layer in sheep following prenatal intra-amniotic injection of lipopolysaccharide. THE CEREBELLUM 2012; 11:132-44. [PMID: 21773814 PMCID: PMC3311858 DOI: 10.1007/s12311-011-0297-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Chorioamnionitis is an important problem in perinatology today, leading to brain injury and neurological handicaps. However, there are almost no data available regarding chorioamnionitis and a specific damage of the cerebellum. Therefore, this study aimed at determining if chorioamnionitis causes cerebellar morphological alterations. Chorioamnionitis was induced in sheep by the intra-amniotic injection of lipopolysaccharide (LPS) at a gestational age (GA) of 110 days. At a GA of 140 days, we assessed the mean total and layer-specific volume and the mean total granule cell (GCs) and Purkinje cell (PC) number in the cerebelli of LPS-exposed and control animals using high-precision design-based stereology. Astrogliosis was assessed in the gray and white matter (WM) using a glial fibrillary acidic protein staining combined with gray value image analysis. The present study showed an unchanged volume of the total cerebellum as well as the molecular layer, outer and inner granular cell layers (OGL and IGL, respectively), and WM. Interestingly, compared with controls, the LPS-exposed brains showed a statistically significant increase (+20.4%) in the mean total number of GCs, whereas the number of PCs did not show any difference between the two groups. In addition, LPS-exposed animals showed signs of astrogliosis specifically affecting the IGL. Intra-amniotic injection of LPS causes morphological changes in the cerebellum of fetal sheep still detectable at full-term birth. In this study, changes were restricted to the inner granule layer. These cerebellar changes might correspond to some of the motor or non-motor deficits seen in neonates from compromised pregnancies.
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Affiliation(s)
- Eveline Strackx
- Department of Neuroscience and European Graduate School of Neuroscience, Maastricht University, Maastricht, The Netherlands
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Abstract
Prematurely born infants are at increased risk for infection throughout their hospitalization. Various developmentally regulated processes involving the central nervous and respiratory systems may be disrupted by the proinflammatory state associated with infection, resulting in an increased risk for death, chronic lung disease, and adverse neurodevelopmental outcome. This review summarizes the current understanding of the long-term impact of infection and/or inflammation in preterm infants, including the risks associated with perinatal infection, early-onset sepsis, late-onset sepsis, and necrotizing enterocolitis.
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Affiliation(s)
- Ira Adams-Chapman
- Division of Neonatology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30303, USA.
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Kuypers E, Ophelders D, Jellema RK, Kunzmann S, Gavilanes AW, Kramer BW. White matter injury following fetal inflammatory response syndrome induced by chorioamnionitis and fetal sepsis: lessons from experimental ovine models. Early Hum Dev 2012; 88:931-6. [PMID: 23078831 DOI: 10.1016/j.earlhumdev.2012.09.011] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Chorioamnionitis and fetal sepsis can induce a fetal inflammatory response syndrome (FIRS) which is closely related to the development of white matter injury in the fetal brain. Large epidemiological studies support the link between FIRS and fetal brain injury with a clear association between the presence of in utero inflammation and neurodevelopmental complications such as cerebral palsy, autism and cognitive impairments later in life. Translational animal models of chorioamnionitis and fetal sepsis are essential in understanding the underlying pathophysiological mechanisms of fetal brain injury after exposure to intra-uterine inflammation. Concerning this aspect, ovine models have high translational value since neurodevelopment in sheep closely resembles the human situation. In this article, we will review clinical and experimental evidence for the link between FIRS and white matter injury in the fetal brain. With respect to experimental findings, we will particularly focus on the lessons learned from ovine models of chorioamnionitis and fetal sepsis. We also highlight two key players implied in the pathophysiology of white matter injury after in utero exposure to inflammation.
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Affiliation(s)
- Elke Kuypers
- Department of Pediatrics, Maastricht University Medical Center, Maastricht, The Netherlands
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Variable ventilation enhances ventilation without exacerbating injury in preterm lambs with respiratory distress syndrome. Pediatr Res 2012; 72:384-92. [PMID: 22805999 DOI: 10.1038/pr.2012.97] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND As compared with constant respiratory rate (RR) and tidal volume (V(T)) during controlled conventional mechanical ventilation (CV), variable ventilation (VV) using the same breath-to-breath minute volume but variable V(T) and RRs enhances ventilation efficiency in preterm lambs. We hypothesized that if V(T) was adjusted to target permissive hypercarbia, VV would result in more efficient gas exchange without increasing inflammatory and injurious responses in the lung. METHODS Preterm lambs at 129 d gestation were anesthetized, tracheotomized, and randomized to either CV (n = 8) or VV (n = 8) using the same initial average V(T) and RR. Lung mechanics and gas exchange were measured intermittently, and average V(T) was adjusted to target partial pressure of arterial carbon dioxide (PaCO2) of 40-50 mm Hg for 3 h. Lung injury and inflammation were assessed from bronchoalveolar lavage fluid, lung tissue, and peripheral blood. RESULTS VV achieved permissive hypercarbia using a lower average V(T), peak inspiratory pressure, and elastance (increased compliance) as compared with CV. Oxygenation and markers of lung tissue inflammation or injury were not different apart from a lower wet:dry tissue ratio in the VV lungs. CONCLUSIONS VV improves ventilation efficiency and in vivo lung compliance in the ovine preterm lung without increasing lung inflammation or lung injury.
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Abstract
Very preterm infants are commonly exposed to a chronic, often asymptomatic, chorioamnionitis that is diagnosed by histologic evaluation of the placenta only after delivery. The reported effects of these exposures on fetal lungs are inconsistent because exposure to different organisms, durations of exposure, and fetal/maternal responses affect outcomes. In experimental models, chorioamnionitis can both injure and mature the fetal lung and cause immune nodulation. Postnatal care strategies also change how chorioamnionitis relates to clinical outcomes such as bronchopulmonary dysplasia.
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Affiliation(s)
- Alan Jobe
- Cincinnati Children’s Hospital Medical Center, Division of Pulmonary Biology, University of Cincinnati, Cincinnati, OH
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66
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Atik A, Sozo F, Orgeig S, Suri L, Hanita T, Harding R, De Matteo R. Long-Term Pulmonary Effects of Intrauterine Exposure to Endotoxin Following Preterm Birth in Sheep. Reprod Sci 2012; 19:1352-64. [DOI: 10.1177/1933719112450327] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Anzari Atik
- Department of Anatomy & Developmental Biology, Monash University, Clayton, Australia
| | - Foula Sozo
- Department of Anatomy & Developmental Biology, Monash University, Clayton, Australia
| | - Sandra Orgeig
- Sansom Institute for Health Research and School of Pharmacy & Medical Sciences, University of South Australia, Adelaide, Australia
| | - Lakshmi Suri
- Sansom Institute for Health Research and School of Pharmacy & Medical Sciences, University of South Australia, Adelaide, Australia
| | - Takushi Hanita
- Department of Anatomy & Developmental Biology, Monash University, Clayton, Australia
| | - Richard Harding
- Department of Anatomy & Developmental Biology, Monash University, Clayton, Australia
| | - Robert De Matteo
- Department of Anatomy & Developmental Biology, Monash University, Clayton, Australia
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67
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Affiliation(s)
- A H Jobe
- Cincinnati Children's Hospital Medical Center, Department of Pulmonary Biology, University of Cincinnati, Cincinnati, Ohio 45229–3039, USA.
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Westover AJ, Hooper SB, Wallace MJ, Moss TJM. Prostaglandins mediate the fetal pulmonary response to intrauterine inflammation. Am J Physiol Lung Cell Mol Physiol 2012; 302:L664-78. [DOI: 10.1152/ajplung.00297.2011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Intra-amniotic (IA) lipopolysaccharide (LPS) induces intrauterine and fetal lung inflammation and increases lung surfactant and compliance in preterm sheep; however, the mechanisms are unknown. Prostaglandins (PGs) are inflammatory mediators, and PGE2 has established roles in fetal lung surfactant production. The aim of our first study was to determine PGE2 concentrations in response to IA LPS and pulmonary gene expression for PG synthetic [prostaglandin H synthase-2 (PGHS-2) and PGE synthase (PGES)] and PG-metabolizing [prostaglandin dehydrogenase (PGDH)] enzymes and PGE2 receptors. Our second study aimed to block LPS-induced increases in PGE2 with a PGHS-2 inhibitor (nimesulide) and determine lung inflammation and surfactant protein mRNA expression. Pregnant ewes received an IA saline or LPS injection at 118 days of gestation. In study 1, fetal plasma and amniotic fluid were sampled before and at 2, 4, 6, 12, and 24 h after injection and then daily, and fetuses were delivered 2 or 7 days later. Amniotic fluid PGE2 concentrations increased ( P < 0.05) 12 h and 3–6 days after LPS. Fetal lung PGHS-2 mRNA and PGES mRNA increased 2 ( P = 0.0084) and 7 ( P = 0.014) days after LPS, respectively. In study 2, maternal intravenous nimesulide or vehicle infusion began immediately before LPS or saline injection and continued until delivery 2 days later. Nimesulide inhibited LPS-induced increases in PGE2 and decreased fetal lung IL-1β and IL-8 mRNA ( P ≤ 0.002) without altering lung inflammatory cell infiltration. Nimesulide decreased surfactant protein (SP)-A ( P = 0.05), -B ( P = 0.05), and -D ( P = 0.0015) but increased SP-C mRNA ( P = 0.023). Thus PGHS-2 mediates, at least in part, fetal pulmonary responses to inflammation.
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Affiliation(s)
| | - Stuart B. Hooper
- Ritchie Centre, Monash Institute of Medical Research and
- Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria, Australia
| | - Megan J. Wallace
- Ritchie Centre, Monash Institute of Medical Research and
- Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria, Australia
| | - Timothy J. M. Moss
- Ritchie Centre, Monash Institute of Medical Research and
- Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria, Australia
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69
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Melville JM, Bischof RJ, Meeusen EN, Westover AJ, Moss TJM. Changes in fetal thymic immune cell populations in a sheep model of intrauterine inflammation. Reprod Sci 2012; 19:740-7. [PMID: 22421448 DOI: 10.1177/1933719111432873] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Intrauterine inflammation is a common antecedent of preterm birth and can alter the development of the fetal thymus, the site of development, and maturation of T lymphocytes. The effects of intrauterine inflammation on specific thymic T lymphocyte populations are largely unknown. We hypothesized that intrauterine inflammation would alter fetal thymic T cell populations. Immunohistochemistry was used to quantitate the relative proportions of thymic cortical and medullary cell populations in fetal sheep 7 days after intra-amniotic lipopolysaccharide (LPS) injection. The proportions of CD8⁺and MHC II⁺ cells in the fetal thymus were reduced in response to LPS. The ratio of CD4:CD8 cells was increased by LPS exposure. No changes were observed in the percentage of CD4⁺, γδ(WC1)⁺, CD45R⁺B cells, or CD44⁺ cells. These studies indicate that intrauterine inflammation impacts thymic composition of CD8 T cells and the development and/or activation of CD4 T cells in the fetal thymus.
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Affiliation(s)
- Jacqueline M Melville
- The Ritchie Centre, Monash Institute of Medical Research, Monash University, Clayton, Victoria, Australia.
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70
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Wolfs TGAM, Jellema RK, Turrisi G, Becucci E, Buonocore G, Kramer BW. Inflammation-induced immune suppression of the fetus: a potential link between chorioamnionitis and postnatal early onset sepsis. J Matern Fetal Neonatal Med 2012; 25 Suppl 1:8-11. [PMID: 22348330 DOI: 10.3109/14767058.2012.664447] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Chorioamnionitis which results from microbial invasion of the amniotic cavity is the most frequent cause of preterm birth. Chorioamnionitis is associated with an increased risk of early-onset sepsis but the mechanisms underlying this association remain largely unknown. We hypothesize that developmental alterations of fetal organs and the immune system in the course of chorioamnionitis determine the risk of development of early onset sepsis. The purpose of this review is therefore to summarize the consequences of chorioamnionitis on fetal development and speculate how those antenatal changes might predispose to early onset sepsis.
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Affiliation(s)
- Tim G A M Wolfs
- Maastricht University Medical Center, Department of Pediatrics, School of Oncology and Developmental Biology, Maastricht, The Netherlands
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71
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Kemp MW, Saito M, Kallapur SG, Jobe AH, Keelan JA, Li S, Kramer B, Zhang L, Knox C, Yaegashi N, Newnham JP. Inflammation of the fetal ovine skin following in utero exposure to Ureaplasma parvum. Reprod Sci 2012; 18:1128-37. [PMID: 22031190 DOI: 10.1177/1933719111408114] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
There is increasing evidence linking in utero infection and inflammation to preterm birth. Many commensal urogenital tract microorganisms, including the Mycoplasmas and Ureaplasmas, are commonly detected in association with preterm birth. Using an ovine model of sterile fetal inflammation, we demonstrated previously that the fetal skin generates a robust inflammatory response following in utero exposure to lipopolysaccharides from Escherichia coli. The fetal skin's response to colonization of the amniotic fluid by viable microorganisms remains unstudied. We hypothesised that in utero infection with Ureaplasma parvum serovar 3 would induce a proinflammatory response in the fetal skin. We found that (1) cultured fetal keratinocytes (the primary cellular constituent of the epidermis) respond to U. parvum exposure in vitro by increasing the expression of the chemotactant monocyte chemoattractant protein 1 (MCP-1) but not interleukin 1β (IL-1β), IL-6, IL-8, or tumor necrosis factor-α (TNF-α); (2) the fetal skin's response to 7 days of U. parvum exposure is characterized by elevated expression of MCP-1, TNF-α, and IL-10; and (3) the magnitude of inflammatory cytokine/chemokine expression in the fetal skin is dependent on the duration of U parvum exposure. These novel findings provide further support for the role of the fetal skin in the development of fetal inflammation and the preterm birth that may follow.
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Affiliation(s)
- Matthew W Kemp
- School of Women's and Infants' Health, The University of Western Australia, Perth, Australia.
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72
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Adams Waldorf KM, Gravett MG, McAdams RM, Paolella LJ, Gough GM, Carl DJ, Bansal A, Liggitt HD, Kapur RP, Reitz FB, Rubens CE. Choriodecidual group B streptococcal inoculation induces fetal lung injury without intra-amniotic infection and preterm labor in Macaca nemestrina. PLoS One 2011; 6:e28972. [PMID: 22216148 PMCID: PMC3244436 DOI: 10.1371/journal.pone.0028972] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Accepted: 11/18/2011] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Early events leading to intrauterine infection and fetal lung injury remain poorly defined, but may hold the key to preventing neonatal and adult chronic lung disease. Our objective was to establish a nonhuman primate model of an early stage of chorioamnionitis in order to determine the time course and mechanisms of fetal lung injury in utero. METHODOLOGY/PRINCIPAL FINDINGS Ten chronically catheterized pregnant monkeys (Macaca nemestrina) at 118-125 days gestation (term=172 days) received one of two treatments: 1) choriodecidual and intra-amniotic saline (n=5), or 2) choriodecidual inoculation of Group B Streptococcus (GBS) 1×10(6) colony forming units (n=5). Cesarean section was performed regardless of labor 4 days after GBS or 7 days after saline infusion to collect fetal and placental tissues. Only two GBS animals developed early labor with no cervical change in the remaining animals. Despite uterine quiescence in most cases, blinded review found histopathological evidence of fetal lung injury in four GBS animals characterized by intra-alveolar neutrophils and interstitial thickening, which was absent in controls. Significant elevations of cytokines in amniotic fluid (TNF-α, IL-8, IL-1β, IL-6) and fetal plasma (IL-8) were detected in GBS animals and correlated with lung injury (p<0.05). Lung injury was not directly caused by GBS, because GBS was undetectable in amniotic fluid (~10 samples tested/animal), maternal and fetal blood by culture and polymerase chain reaction. In only two cases was GBS cultured from the inoculation site in low numbers. Chorioamnionitis occurred in two GBS animals with lung injury, but two others with lung injury had normal placental histology. CONCLUSIONS/SIGNIFICANCE A transient choriodecidual infection can induce cytokine production, which is associated with fetal lung injury without overt infection of amniotic fluid, chorioamnionitis or preterm labor. Fetal lung injury may, thus, occur silently without symptoms and before the onset of the fetal systemic inflammatory response syndrome.
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73
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Kuypers E, Collins JJP, Kramer BW, Ofman G, Nitsos I, Pillow JJ, Polglase GR, Kemp MW, Newnham JP, Gavilanes AWD, Nowacki R, Ikegami M, Jobe AH, Kallapur SG. Intra-amniotic LPS and antenatal betamethasone: inflammation and maturation in preterm lamb lungs. Am J Physiol Lung Cell Mol Physiol 2011; 302:L380-9. [PMID: 22160306 DOI: 10.1152/ajplung.00338.2011] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The proinflammatory stimulus of chorioamnionitis is commonly associated with preterm delivery. Women at risk of preterm delivery receive antenatal glucocorticoids to functionally mature the fetal lung. However, the effects of the combined exposures of chorioamnionitis and antenatal glucocorticoids on the fetus are poorly understood. Time-mated ewes with singleton fetuses received an intra-amniotic injection of lipopolysaccharide (LPS) either preceding or following maternal intramuscular betamethasone 7 or 14 days before delivery, and the fetuses were delivered at 120 days gestational age (GA) (term = 150 days GA). Gestation matched controls received intra-amniotic and maternal intramuscular saline. Compared with saline controls, intra-amniotic LPS increased inflammatory cells in the bronchoalveolar lavage and myeloperoxidase, Toll-like receptor 2 and 4 mRNA, PU.1, CD3, and Foxp3-positive cells in the fetal lung. LPS-induced lung maturation measured as increased airway surfactant and improved lung gas volumes. Intra-amniotic LPS-induced inflammation persisted until 14 days after exposure. Betamethasone treatment alone induced modest lung maturation but, when administered before intra-amniotic LPS, suppressed lung inflammation. Interestingly, betamethasone treatment after LPS did not counteract inflammation but enhanced lung maturation. We conclude that the order of exposures of intra-amniotic LPS or maternal betamethasone had large effects on fetal lung inflammation and maturation.
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Affiliation(s)
- Elke Kuypers
- Department of Pediatrics, School for Oncology and Developmental Biology, Maastricht University Medical Center, The Netherlands
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74
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Polglase GR, Nitsos I, Baburamani AA, Crossley KJ, Slater MK, Gill AW, Allison BJ, Moss TJM, Pillow JJ, Hooper SB, Kluckow M. Inflammation in utero exacerbates ventilation-induced brain injury in preterm lambs. J Appl Physiol (1985) 2011; 112:481-9. [PMID: 22052871 DOI: 10.1152/japplphysiol.00995.2011] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cerebral blood flow disturbance is a major contributor to brain injury in the preterm infant. The initiation of ventilation may be a critical time for cerebral hemodynamic disturbance leading to brain injury in preterm infants, particularly if they are exposed to inflammation in utero. We aimed to determine whether exposure to inflammation in utero alters cardiopulmonary hemodynamics, resulting in cerebral hemodynamic disturbance and related brain injury during the initiation of ventilation. Furthermore, we aimed to determine whether inflammation in utero alters the cerebral hemodynamic response to challenge induced by high mean airway pressures. Pregnant ewes received intra-amniotic lipopolysaccharide (LPS) or saline either 2 or 4-days before preterm delivery (at 128 ± 1 days of gestation). Lambs were surgically instrumented for assessment of pulmonary and cerebral hemodynamics before delivery and positive pressure ventilation. After 30 min, lambs were challenged hemodynamically by incrementing and decrementing positive end-expiratory pressure. Blood gases, arterial pressures, and blood flows were recorded. The brain was collected for biochemical and histological assessment of inflammation, brain damage, vascular extravasation, hemorrhage, and oxidative injury. Carotid arterial pressure was higher and carotid blood flow was more variable in 2-day LPS lambs than in controls during the initial 15 min of ventilation. All lambs responded similarly to the hemodynamic challenge. Both 2- and 4-day LPS lambs had increased brain interleukin (IL)-1β, IL-6, and IL-8 mRNA expression; increased number of inflammatory cells in the white matter; increased incidence and severity of brain damage; and vascular extravasation relative to controls. Microvascular hemorrhage was increased in 2-day LPS lambs compared with controls. Cerebral oxidative injury was not different between groups. Antenatal inflammation causes adverse cerebral hemodynamics and increases the incidence and severity of brain injury in ventilated preterm lambs.
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Affiliation(s)
- Graeme R Polglase
- Ritchie Centre, Monash Institute of Medical Research, Monash University, Clayton, Victoria, Australia.
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75
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Musk GC, Netto JD, Maker GL, Trengove RD. Transplacental transfer of medetomidine and ketamine in pregnant ewes. Lab Anim 2011; 46:46-50. [PMID: 22008849 DOI: 10.1258/la.2011.010179] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The extent of placental transfer of medetomidine and ketamine is unknown in pregnant ewes. Date-mated singleton (n = 8) and twin (n = 8) pregnant merino cross ewes were anaesthetized for Caesarean delivery of preterm lamb fetuses. A combination of medetomidine (20 μg/kg) and ketamine (10 mg/kg) was administered by intravenous injection and surgery performed immediately thereafter. Blood samples were collected from the ewe at one, five and 10 min after intravenous injection and from the umbilical vein of the fetus at delivery. Non-pregnant ewes were also anaesthetized (n = 8). There was no difference in the plasma concentration of medetomidine or ketamine when comparing singleton and twin ewes or pregnant and non-pregnant ewes for the short duration of the study. Fetal plasma concentrations of each drug were comparable to the maternal concentrations at the same time. We conclude that both drugs cross the placenta readily and provide anaesthesia and analgesia for the fetus when it is delivered.
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Affiliation(s)
- G C Musk
- School of Veterinary and Biomedical Sciences, Murdoch University, Western Australia 6150, Australia.
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76
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Kallapur SG, Kramer BW, Knox CL, Berry CA, Collins JJP, Kemp MW, Nitsos I, Polglase GR, Robinson J, Hillman NH, Newnham JP, Chougnet C, Jobe AH. Chronic fetal exposure to Ureaplasma parvum suppresses innate immune responses in sheep. THE JOURNAL OF IMMUNOLOGY 2011; 187:2688-95. [PMID: 21784974 DOI: 10.4049/jimmunol.1100779] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The chorioamnionitis associated with preterm delivery is often polymicrobial with ureaplasma being the most common isolate. To evaluate interactions between the different proinflammatory mediators, we hypothesized that ureaplasma exposure would increase fetal responsiveness to LPS. Fetal sheep were given intra-amniotic (IA) injections of media (control) or Ureaplasma parvum serovar 3 either 7 or 70 d before preterm delivery. Another group received an IA injection of Escherichia coli LPS 2 d prior to delivery. To test for interactions, IA U. parvum-exposed animals were challenged with IA LPS and delivered 2 d later. All animals were delivered at 124 ± 1-d gestation (term = 150 d). Compared with the 2-d LPS exposure group, the U. parvum 70 d + LPS group had 1) decreased lung pro- and anti-inflammatory cytokine expression and 2) fewer CD3(+) T lymphocytes, CCL2(+), myeloperoxidase(+), and PU.1(+) cells in the lung. Interestingly, exposure to U. parvum for 7 d did not change responses to a subsequent IA LPS challenge, and exposure to IA U. parvum alone induced mild lung inflammation. Exposure to U. parvum increased pulmonary TGF-β1 expression but did not change mRNA expression of either the receptor TLR4 or some of the downstream mediators in the lung. Monocytes from fetal blood and lung isolated from U. parvum 70 d + LPS but not U. parvum 7 d + LPS animals had decreased in vitro responsiveness to LPS. These results are consistent with the novel finding of downregulation of LPS responses by chronic but not acute fetal exposures to U. parvum. The findings increase our understanding of how chorioamnionitis-exposed preterm infants may respond to lung injury and postnatal nosocomial infections.
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Affiliation(s)
- Suhas G Kallapur
- Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, OH 45229, USA.
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77
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Kallapur SG, Kramer BW, Nitsos I, Pillow JJ, Collins JJP, Polglase GR, Newnham JP, Jobe AH. Pulmonary and systemic inflammatory responses to intra-amniotic IL-1α in fetal sheep. Am J Physiol Lung Cell Mol Physiol 2011; 301:L285-95. [PMID: 21665964 DOI: 10.1152/ajplung.00446.2010] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Clinical and epidemiological studies implicate IL-1 as an important mediator of perinatal inflammation. We tested the hypothesis that intra-amniotic IL-1α would induce pulmonary and systemic fetal inflammatory responses. Sheep with singleton fetuses were given an intra-amniotic injection of recombinant sheep IL-1α (100 μg) and were delivered 1, 3, or 7 days later, at 124 ± 1 days gestation (n=5-8/group). A separate group of sheep were given two intra-amniotic IL-1α injections (100 μg dose each): 7 days and again 1 day prior to delivery. IL-1α induced a robust increase in monocytes, neutrophils, lymphocytes, and IL-8 protein in bronchoalveolar lavage fluid. H(2)O(2) secretion was increased in inflammatory cells isolated from lungs of IL-1α-exposed lambs upon LPS challenge in vitro compared with control monocytes. T lymphocytes were recruited to the lung. IL-1β, cyclooxygenase-1, and cyclooxygenase-2 mRNA expression increased in the lung 1 day after intra-amniotic IL-1α exposure. Lung volumes increased 7 days after intra-amniotic IL-1α exposure, with minimal anatomic changes in air space morphology. The weight of the posterior mediastinal lymph node draining the lung and the gastrointestinal tract doubled, inducible nitric oxide synthase (NOSII)-positive cells increased, and Foxp3-positive T-regulatory lymphocytes decreased in the lymph node after IL-1α exposure. In the blood, neutrophil counts and plasma haptoglobin increased after IL-1α exposure. Compared with a single exposure, exposure to intra-amniotic IL-1α 7 days and again 1 day before delivery had a variable effect (increases in some inflammatory markers, but not pulmonary cytokines). IL-1α is a potent mediator of the fetal inflammatory response syndrome.
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Affiliation(s)
- Suhas G Kallapur
- Cincinnati Children's Hospital Medical Center, Univ. of Cincinnati, Division of Pulmonary Biology, 3333 Burnet Ave., Cincinnati, OH 45229-3039, USA.
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78
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Galinsky R, Moss TJM, Gubhaju L, Hooper SB, Black MJ, Polglase GR. Effect of intra-amniotic lipopolysaccharide on nephron number in preterm fetal sheep. Am J Physiol Renal Physiol 2011; 301:F280-5. [PMID: 21593183 DOI: 10.1152/ajprenal.00066.2011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Chorioamnionitis is an antecedent of preterm birth. We aimed to determine the effect of experimental chorioamnionitis in fetal sheep during late gestation on 1) nephron number, 2) renal corpuscle volume, and 3) renal inflammation. We hypothesized that exposure to chorioamnionitis would lead to inflammation in fetal kidneys and adversely impact on the development of nephrons, leading to a reduction in nephron number. At ∼121 days of gestation (term ∼147 days), pregnant ewes bearing twin or singleton fetuses received a single intra-amniotic injection of lipopolysaccharide (n = 6; 3 singletons, 3 twins); controls were either untreated or received an intra-amniotic injection of saline (n = 8; 4 singletons, 4 twins). One twin was used from each twin-bearing ewe. At ∼128 days of gestation, fetuses were delivered via Caesarean section. Kidneys were collected and stereologically analyzed to determine nephron number and renal corpuscle volume. Renal inflammation was assessed using immunohistochemistry. Experimental chorioamnionitis did not affect body weight or relative kidney weight. There was a significant reduction in nephron number but no change in renal corpuscle volume in LPS-exposed fetuses relative to controls. On average, nephron number was significantly reduced by 23 and 18% in singleton and twin LPS-exposed fetuses, respectively. The degree of renal inflammation did not differ between groups. Importantly, this study demonstrates that exposure to experimental chorioamnionitis adversely impacts on nephron number in the developing fetus.
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Affiliation(s)
- Robert Galinsky
- The Ritchie Centre, Monash Institute of Medical Research, Monash University, Clayton, Victoria, Australia.
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79
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Fetal lipopolysaccharide exposure modulates diet-dependent gut maturation and sensitivity to necrotising enterocolitis in pre-term pigs. Br J Nutr 2011; 106:852-61. [PMID: 21676273 DOI: 10.1017/s000711451100047x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Uterine infections during pregnancy predispose to pre-term birth and postnatal morbidity, but it is unknown how prenatal bacterial exposure affects maturation of the immature gut. We hypothesised that a prenatal exposure to gram-negative lipopolysaccharide (LPS) has immunomodulatory effects that improve resistance towards necrotising enterocolitis (NEC) in pre-term neonates. At approximately 85 % gestation, pig fetuses were injected intramuscularly with saline or LPS (0·014 mg/kg), or intra-amniotically with LPS (0·4 mg/kg). Pigs were delivered by caesarean section 3-5 d later and fed colostrum (C) or formula (F) for 48 h. Gut indices did not differ between pigs injected intramuscularly with saline or LPS, and these groups were therefore pooled into two control groups according to diet (control-F, n 32 and control-C, n 11). Control-F pigs showed reduced villus heights, mucosal structure, gut integrity, digestive enzymes, elevated NEC incidence (38 v. 0 %, P < 0·05) and several differentially expressed immune-related genes, relative to control-C pigs. Compared with the control-F and control-C groups, values in formula-fed pigs given intra-amniotic LPS formula (n 17) were intermediate for villus height, enzyme activities, intestinal permeability and NEC incidence (18 %, P = 0·2 relative to control-F), and numbers of differentially expressed immune genes. In conclusion, prenatal exposure of the fetal gut to Gram-negative bacteria may modulate the immediate postnatal response to an enteral diet and colonising bacteria.
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80
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Pillow JJ, Musk GC, McLean CM, Polglase GR, Dalton RGB, Jobe AH, Suki B. Variable ventilation improves ventilation and lung compliance in preterm lambs. Intensive Care Med 2011; 37:1352-9. [DOI: 10.1007/s00134-011-2237-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Accepted: 02/23/2011] [Indexed: 11/29/2022]
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81
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Kunzmann S, Collins JJP, Yang Y, Uhlig S, Kallapur SG, Speer CP, Jobe AH, Kramer BW. Antenatal inflammation reduces expression of caveolin-1 and influences multiple signaling pathways in preterm fetal lungs. Am J Respir Cell Mol Biol 2011; 45:969-76. [PMID: 21562314 DOI: 10.1165/rcmb.2010-0519oc] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Bronchopulmonary dysplasia (BPD), associated with chorioamnionitis, results from the simultaneous effects of disrupted lung development, lung injury, and repair superimposed on the developing lung. Caveolins (Cavs) are implicated as major modulators of lung injury and remodeling by multiple signaling pathways, although Cavs have been minimally studied in the injured developing lung. We hypothesized that chorioamnionitis-associated antenatal lung inflammation would decrease the expression of Cav-1 in preterm fetal lungs. We tested whether changes occurred in the transcription factors Smad2/3, Smad1/5, Stat3, and Stat1, and we also studied the activation of acid-sphingomyelinase (a-SMase) with the generation of ceramide, along with changes in the expression of heme oxygenase-1 (HO-1) as indicators of possible Cav-1-mediated effects. Fetal sheep were exposed to 10 mg of intra-amniotic endotoxin or saline for 2, 7, or 2 + 7 days before preterm delivery at 124 days of gestation. The expression of Cav-1 and HO-1 and the phosphorylation of Smad and Stat were evaluated by real-time PCR, Western blotting, and/or immunohistochemistry. The activity of a-SMase and the concentrations of ceramide were measured. Intra-amniotic endotoxin decreased Cav-1 mRNA and protein expression in the lungs, with a maximum reduction of Cav-1 mRNA to 50% ± 7% of the control value (P < 0.05), and of Cav-1 protein expression to 20% ± 5% of the control value (P < 0.05). Decreased concentrations of Cav-1 were associated with the elevated phosphorylation of Smad2/3, Stat3, and Stat1, but not of Smad1/5. The expression of HO-1, a-SMase activity, and ceramide increased. Antenatal inflammation decreased the expression of Cav-1 in the preterm fetal lung. The decreased expression of Cav-1 was associated with the activation of the Smad2/3, Stat, and a-SMase/ceramide pathways, and with the increased expression of HO-1. The decreased concentrations of Cav-1 and changes in other signaling pathways may contribute to BPD.
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Affiliation(s)
- Steffen Kunzmann
- University Children's Hospital, University of Würzburg, Germany.
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82
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Berry CA, Nitsos I, Hillman NH, Pillow JJ, Polglase GR, Kramer BW, Kemp MW, Newnham JP, Jobe AH, Kallapur SG. Interleukin-1 in lipopolysaccharide induced chorioamnionitis in the fetal sheep. Reprod Sci 2011; 18:1092-102. [PMID: 21493953 DOI: 10.1177/1933719111404609] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We tested the hypothesis that interleukin 1 (IL-1) mediates intra-amniotic lipopolysaccharide (LPS)-induced chorioamnionitis in preterm fetal sheep. Time-mated Merino ewes with singleton fetuses received IL-1α, LPS, or saline (control) by intra-amniotic injection 1 to 2 days before operative delivery at 124 ± 1 days gestational age (N = 5-9/group; term = 150 days). Recombinant human IL-1 receptor antagonist (rhIL-1ra) was given into the amniotic fluid 3 hours before intra-amniotic LPS or saline to block IL-1 signaling. Inflammation in the chorioamnion was determined by histology, cytokine messenger RNA (mRNA), protein expression, and by quantitation of activated inflammatory cells. Intra-amniotic IL-1 and LPS both induced chorioamnionitis. However, IL-1 blockade with IL-1ra did not decrease intra-amniotic LPS-induced increases in pro-inflammatory cytokine mRNAs, numbers of inflammatory cells, myeloperoxidase, or monocyte chemotactic protein-1-expressing cells in the chorioamnion. We conclude that IL-1 and LPS both can cause chorioamnionitis, but IL-1 is not an important mediator of LPS-induced chorioamnionitis in fetal sheep.
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Affiliation(s)
- Clare A Berry
- Division of Pulmonary Biology/Neonatology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
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Hillman NH, Polglase GR, Jane Pillow J, Saito M, Kallapur SG, Jobe AH. Inflammation and lung maturation from stretch injury in preterm fetal sheep. Am J Physiol Lung Cell Mol Physiol 2011; 300:L232-41. [PMID: 21131401 PMCID: PMC3043810 DOI: 10.1152/ajplung.00294.2010] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mechanical ventilation is a risk factor for the development of bronchopulmonary dysplasia in premature infants. Fifteen minutes of high tidal volume (V(T)) ventilation induces inflammatory cytokine expression in small airways and lung parenchyma within 3 h. Our objective was to describe the temporal progression of cytokine and maturation responses to lung injury in fetal sheep exposed to a defined 15-min stretch injury. After maternal anesthesia and hysterotomy, 129-day gestation fetal lambs (n = 7-8/group) had the head and chest exteriorized. Each fetus was intubated, and airway fluid was gently removed. While placental support was maintained, the fetus received ventilation with an escalating V(T) to 15 ml/kg without positive end-expiratory pressure (PEEP) for 15 min using heated, humidified 100% nitrogen. The fetus was then returned to the uterus for 1, 6, or 24 h. Control lambs received a PEEP of 2 cmH(2)O for 15 min. Tissue samples from the lung and systemic organs were evaluated. Stretch injury increased the early response gene Egr-1 and increased expression of pro- and anti-inflammatory cytokines within 1 h. The injury induced granulocyte/macrophage colony-stimulating factor mRNA and matured monocytes to alveolar macrophages by 24 h. The mRNA for the surfactant proteins A, B, and C increased in the lungs by 24 h. The airway epithelium demonstrated dynamic changes in heat shock protein 70 (HSP70) over time. Serum cortisol levels did not increase, and induction of systemic inflammation was minimal. We conclude that a brief period of high V(T) ventilation causes a proinflammatory cascade, a maturation of lung monocytic cells, and an induction of surfactant protein mRNA.
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Affiliation(s)
- Noah H. Hillman
- 1Division of Pulmonary Biology, Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio; and
| | - Graeme R. Polglase
- 2School of Women's and Infants' Health, The University of Western Australia, Perth, Australia
| | - J. Jane Pillow
- 2School of Women's and Infants' Health, The University of Western Australia, Perth, Australia
| | - Masatoshi Saito
- 2School of Women's and Infants' Health, The University of Western Australia, Perth, Australia
| | - Suhas G. Kallapur
- 1Division of Pulmonary Biology, Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio; and ,2School of Women's and Infants' Health, The University of Western Australia, Perth, Australia
| | - Alan H. Jobe
- 1Division of Pulmonary Biology, Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio; and ,2School of Women's and Infants' Health, The University of Western Australia, Perth, Australia
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84
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Kwinta P, Pietrzyk JJ. Preterm birth and respiratory disease in later life. Expert Rev Respir Med 2011; 4:593-604. [PMID: 20923339 DOI: 10.1586/ers.10.59] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Chronic respiratory diseases are a common complication of preterm birth, particularly among very immature infants or those suffering from bronchopulmonary dysplasia. Major progress in the treatment of preterm newborns has changed the pattern of late respiratory complications. The major respiratory problem in infancy and early childhood is respiratory exacerbations caused by infections (particularly viral ones), which need hospitalization. The symptoms become mild in school-age children; however, a group of children still present with chronic airway obstruction defined by recurrent episodes of wheezing and decreased lung function tests (decreased forced expiratory volume). For some preterm infants, particularly those with bronchopulmonary dysplasia, obstructive lung disease persists into adulthood. They are very likely to develop chronic obstructive pulmonary disease or similar disease later in life. In these patients, a program of lung function monitoring and pulmonary prophylaxis by means of elimination of specific risk factors in adulthood is advisable.
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85
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Abstract
Antenatal inflammation may be associated with adverse neonatal outcomes in several organ systems. Bacteria and a few viruses have been detected in cases of microbial invasion of the amniotic cavity which is referred to as chorioamnionitis. Many aspects of this disease remain unclear such as the causes, time of onset and the fetal responses. Chorioamnionitis was therefore induced in pregnant sheep by injections of lipopolysaccharide (LPS) or Ureaplasma species into the amniotic cavity under ultrasound guidance. LPS-induced chorioamnionitis caused a cascade of organ injury, inflammation, and remodeling. The organ-specific changes were accompanied by systemic effects. The systemic effects after LPS-induced chorioamnionitis resulted in immune suppression against several Toll-like receptor agonists (cross-tolerance). Ureaplasma induced chorioamnionitis made changes in the fetal lung structure depending on the time of infection during pregnancy. The mechanisms of inflammation, structural damage and decreased expression of growth factors need to be further studied to determine therapeutic targets in suitable animal models.
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Affiliation(s)
- Boris W Kramer
- Division of Neonatology, Department of Pediatrics, Maastricht University Medical Center, Maastricht, The Netherlands.
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86
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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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87
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Collins JJP, Kallapur SG, Knox CL, Nitsos I, Polglase GR, Pillow JJ, Kuypers E, Newnham JP, Jobe AH, Kramer BW. Inflammation in fetal sheep from intra-amniotic injection of Ureaplasma parvum. Am J Physiol Lung Cell Mol Physiol 2010; 299:L852-60. [PMID: 20935228 DOI: 10.1152/ajplung.00183.2010] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Bronchopulmonary dysplasia is associated with chorioamnionitis and fetal lung inflammation. Ureaplasma species are the bacteria most frequently isolated from chorioamnionitis. Very chronic ureaplasma colonization of amniotic fluid causes low-grade lung inflammation and functional lung maturation in fetal sheep. Less is known about shorter exposures of the fetal lung. Therefore, we hypothesized that ureaplasmas would cause an acute inflammatory response that would alter lung development. Singleton ovine fetuses received intra-amniotic Ureaplasma parvum serovar 3 or control media at 110, 117, or 121 days and were delivered at 124 days gestational age (term = 150 days). Inflammation was assessed by 1) cell counts in bronchoalveolar lavage fluid (BALF), and 2) cytokine mRNA measurements, immunohistochemistry, and flow cytometry for inflammatory cells and elastin and α-smooth muscle actin (α-SMA) staining in lung tissue. Neutrophils were increased in BALF 3 days after exposure to ureaplasmas (P = 0.01). Myeloperoxidase-positive cells increased after 3 days (P = 0.03), and major histocompatibility complex (MHC) class II-positive cells increased after 14 days of ureaplasma exposure (P = 0.001). PU.1 (macrophage marker)- or CD3 (T lymphocyte marker)-positive cells were not induced by ureaplasmas. CD3-positive cells in the posterior mediastinal lymph node increased in ureaplasma-exposed animals at 3, 7, and 14 days (P = 0.002). Focal elastin depositions decreased in alveolar septa at 14 days (P = 0.002), whereas α-SMA increased in arteries and bronchioli. U. parvum induced a mild acute inflammatory response and changed elastin and α-SMA deposition in the lung, which may affect lung structure and subsequent development.
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88
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Abstract
The bacterial infection of chorion and amnion is a common finding in premature delivery and is referred to as chorioamnionitis. As the mother rarely shows symptoms of a systemic inflammation, the course of chorioamnionitis is frequently asymptomatic and chronic. In contrast, the fetal inflammatory response syndrome represents a separate phenomenon, including umbilical inflammation and increased serum levels of proinflammatory cytokines in the fetus. Ascending maternal infections frequently lead to systemic fetal inflammatory reaction. Clinical studies have shown that antenatal exposure to inflammation puts the extremely immature neonates at a high risk for worsening pulmonary, neurological and other organ development. Interestingly, the presence of chorioamnionitis is associated with a lower rate of neonatal mortality in extremely immature newborns. In the following review, the pathogeneses of inflammation-associated perinatal morbidity are outlined. The concept of fetal multiorganic disease during intrauterine infection is introduced and discussed.
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89
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Polglase GR, Hooper SB, Gill AW, Allison BJ, Crossley KJ, Moss TJM, Nitsos I, Pillow JJ, Kluckow M. Intrauterine inflammation causes pulmonary hypertension and cardiovascular sequelae in preterm lambs. J Appl Physiol (1985) 2010; 108:1757-65. [DOI: 10.1152/japplphysiol.01336.2009] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Chorioamnionitis increases the risk and severity of persistent pulmonary hypertension of the newborn in preterm infants. Exposure of preterm fetal lambs to intra-amniotic (IA) lipopolysaccharide (LPS) induces chorioamnionitis, causes hypertrophy of pulmonary resistance arterioles, and alters expression of pulmonary vascular growth proteins. We investigated the cardiopulmonary and systemic hemodynamic consequences of IA LPS in preterm lambs. Pregnant ewes received IA injection of LPS ( n = 6) or saline (controls; n = 8) at 122 days gestation, 7 days before exteriorization, instrumentation, and delivery of the fetus with pulmonary and systemic flow probes and catheters at 129 days gestation. Newborn lambs were ventilated, targeting a tidal volume of 6–7 ml/kg and a positive end-expiratory pressure (PEEP) of 4 cmH2O. At 30 min, all lambs underwent a PEEP challenge: PEEP was increased by 2 cmH2O at 10-min intervals to 10 cmH2O and then decreased similarly to 4 cmH2O. Ventilation parameters, arterial blood flows, and pressures were recorded in real-time for 90 min. LPS lambs had higher total protein in bronchoalveolar lavage fluid ( P < 0.002), increased medial thickness of arteriolar walls ( P = 0.013), and right ventricular hypertrophy ( P = 0.012). Compared with controls, LPS lambs had worse oxygenation ( P < 0.001), decreased pulmonary blood flow ( P = 0.05), and higher pulsatility index ( P < 0.001) and pulmonary ( P < 0.001) and systemic arterial pressures ( P = 0.005) than controls. Intra-amniotic LPS increased right-to-left shunting across the ductus arteriosus ( P = 0.018) and decreased left ventricular output ( P < 0.001). We conclude that inflammation and pulmonary remodeling induced by IA LPS adversely alters pulmonary hemodynamics with subsequent cardiovascular and systemic sequelae, which may predispose the preterm lamb to persistent pulmonary hypertension of the newborn.
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Affiliation(s)
- Graeme R. Polglase
- School of Women's and Infants' Health, The University of Western Australia, Crawley, Western Australia
- Department of Physiology, Monash University, Clayton, Victoria
| | | | - Andrew W. Gill
- School of Women's and Infants' Health, The University of Western Australia, Crawley, Western Australia
| | - Beth J. Allison
- Department of Physiology, Monash University, Clayton, Victoria
| | | | - Timothy JM Moss
- Department of Physiology, Monash University, Clayton, Victoria
| | - Ilias Nitsos
- School of Women's and Infants' Health, The University of Western Australia, Crawley, Western Australia
| | - J. Jane Pillow
- School of Women's and Infants' Health, The University of Western Australia, Crawley, Western Australia
| | - Martin Kluckow
- Department of Neonatal Medicine, Royal North Shore Hospital and University of Sydney, Sydney, New South Wales, Australia
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90
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Polglase GR, Dalton RGB, Nitsos I, Knox CL, Pillow JJ, Jobe AH, Moss TJM, Newnham JP, Kallapur SG. Pulmonary vascular and alveolar development in preterm lambs chronically colonized with Ureaplasma parvum. Am J Physiol Lung Cell Mol Physiol 2010; 299:L232-41. [PMID: 20495079 DOI: 10.1152/ajplung.00369.2009] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Ureaplasma species, the most commonly isolated microorganisms in women with chorioamnionitis, are associated with preterm delivery. Chorioamnionitis increases the risk and severity of bronchopulmonary dysplasia and persistent pulmonary hypertension in newborns. It is not known whether the timing of exposure to inflammation in utero is an important contributor to the pathogenesis of bronchopulmonary dysplasia. We hypothesized that chronic inflammation would alter the pulmonary air space and vascular development after 70 days of exposure to infection. Pregnant ewes were given intra-amniotic injection of Ureaplasma parvum serovars 3 or 6 at low (2 x 10(4) cfu) or high doses (2 x 10(7) cfu) or media (controls) at 55 days gestational age. Fetuses were delivered at 125 days (term = 150 days). U. parvum was grown from the lungs of all exposed fetuses, and neutrophils and monocytes were increased in the air spaces. Lung mRNA expression of IL-1beta and IL-8, but not IL-6, was modestly increased in U. parvum-exposed fetuses. U. parvum exposure increased surfactant and improved lung gas volumes. The changes in lung inflammation and maturation were independent of serovar or dose. Exposure to U. parvum did not change multiple indices of air space or vascular development. Parenchymal elastin and collagen content were similar between groups. Expression of several endothelial proteins and pulmonary resistance arteriolar media thickness were also not different between groups. We conclude that chronic exposure to U. parvum does not cause sustained effects on air space or vascular development in premature lambs.
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91
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Abstract
The increased survival of very preterm infants is generally attributed to improved care strategies. This review develops the thesis that the features of abnormal pregnancies responsible for very preterm deliveries also provide an explanation of why very preterm infants often survive. A normal fetus born at 24 weeks is very unlikely to survive. However, pregnancies that result in deliveries at 24 weeks are generally highly abnormal, and may have been so for prolonged periods prior to the preterm deliveries. Inflammatory or vascular developmental abnormalities resulting in very preterm birth can alter fetal development in such a way that organ system maturation is induced. This is supported clinically by the relative lack of very preterm infants with respiratory distress syndrome. Interventions such as antenatal corticosteroid treatment and postnatal surfactant treatment for infants with respiratory distress syndrome and gentle ventilation strategies maximize fetal adaptations to the abnormal fetal environment and improve outcomes.
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Affiliation(s)
- Alan H Jobe
- Division of Neonatology/Pulmonary Biology, Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio 45229-3039, USA.
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92
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Schulzke SM, Polglase GR, Sozo F, Pillow JJ. Feasibility and short-term effects of biphasic positive airway pressure versus assist-control ventilation in preterm lambs. Pediatr Res 2009; 66:665-70. [PMID: 19690512 DOI: 10.1203/pdr.0b013e3181bc309d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Biphasic positive airway pressure (BiLevel) ventilation allows utilization of two alternating positive end-expiratory pressures (PEEP) while permitting unrestricted spontaneous breathing with superimposed synchronized pressure support. We aimed to compare whether BiLevel versus assist-control (A-C) ventilation provides effective gas exchange and reduces severity of early lung injury in preterm lambs. Preterm lambs delivered at 134 d (term = 150 d) were quasirandomized to BiLevel (PEEP low/high 5/20 cm H2O) or A-C5 (PEEP 5 cm H2O) ventilation. Ventilation parameters and arterial blood gases were recorded at regular intervals. Postmortem measurements included pressure-volume relationship, lung inflammatory score, wet/dry body weight ratio, and messenger RNA (mRNA) expression of early markers of lung injury. There were no significant differences between groups in baseline characteristics, oxygenation index (p = 0.49), or partial pressure of carbon dioxide (Paco2) (p = 0.08). BiLevel group lambs showed improved pressure-volume relationship (p = 0.006), lower lung inflammatory score (p = 0.013), and trend toward lower messenger RNA expression of markers of lung injury compared with A-C5 group lambs. In unsedated preterm lambs, BiLevel ventilation provides gas exchange equivalent to A-C ventilation and potentially results in reduced lung injury.
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Affiliation(s)
- Sven M Schulzke
- School of Women's and Infant's Health, University of Western Australia, Crawley, Western Australia 6009, Australia.
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93
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Jobe AH, Nitsos I, Pillow JJ, Polglase GR, Kallapur SG, Newnham JP. Betamethasone dose and formulation for induced lung maturation in fetal sheep. Am J Obstet Gynecol 2009; 201:611.e1-7. [PMID: 19800603 DOI: 10.1016/j.ajog.2009.07.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Revised: 05/07/2009] [Accepted: 07/06/2009] [Indexed: 10/20/2022]
Abstract
OBJECTIVE We hypothesized that maternal treatments with betamethasone acetate induce fetal lung maturation comparably to the betamethasone phosphate+betamethasone acetate used clinically. STUDY DESIGN Ewes with singleton pregnancies were treated with single doses of 0.25-mg/kg or 0.5-mg/kg betamethasone acetate, 4 doses of 0.25-mg/kg betamethasone phosphate, a single dose of 0.5-mg/kg betamethasone acetate+0.25-mg/kg betamethasone phosphate, 2 doses of 0.25-mg/kg betamethasone acetate+0.25-mg betamethasone phosphate or vehicle beginning 48 hours before preterm delivery. Fetal lung maturation was evaluated. RESULTS All treatments induced lung maturation relative to vehicle controls. The relatively insoluble betamethasone acetate resulted in low maternal blood betamethasone and no detectable fetal blood betamethasone in 2 of 3 fetuses, but it induced fetal lung maturation comparable to the 2-dose betamethasone acetate+betamethasone phosphate or 4 doses of betamethasone phosphate. CONCLUSION A single maternal dose of betamethasone acetate effectively induces fetal lung maturation in sheep with minimal fetal exposure.
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94
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Kallapur SG, Moss TJM, Auten RL, Nitsos I, Pillow JJ, Kramer BW, Maeda DY, Newnham JP, Ikegami M, Jobe AH. IL-8 signaling does not mediate intra-amniotic LPS-induced inflammation and maturation in preterm fetal lamb lung. Am J Physiol Lung Cell Mol Physiol 2009; 297:L512-9. [PMID: 19574422 DOI: 10.1152/ajplung.00105.2009] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Preterm infants exposed to chorioamnionitis and preterm sheep fetuses exposed to intra-amniotic (IA) LPS have lung inflammation, increased IL-8 levels, and lung maturation. We tested the hypothesis that IL-8 signaling mediates IA LPS-induced lung inflammation and lung maturation. Two strategies were used: 1) we tested if IA injection of recombinant sheep IL-8 (rsIL-8) induced fetal inflammation and 2) if IL-8 signaling was blocked by a novel CXCR2 receptor blocker, nicotinanilide thioglycolate methyl ester (NTME). To test effects of IL-8 in the fetus, rsIL-8 was given intravascularly (50 microg) at 124 +/- 1 day of gestation (term = 150 days). A separate group of sheep was given IA rsIL-8 (100 microg) and delivered 5 h to 7 days later at 124 +/- 1 day of gestation. After confirming efficacy of the CXCR2 inhibitor, effects of IL-8 blockade were tested by injecting fetal sheep intramuscularly with NTME (10 mg) before IA injection of Escherichia coli LPS (10 mg). Sheep fetuses were delivered 1 or 7 days after injections at 124 +/- 1 day of gestation. IA rsIL-8 induced a modest fivefold increase in bronchoalveolar lavage (BAL) monocytes and neutrophils and increased lung monocyte hydrogen peroxide generation. However, rsIL-8 did not induce lung maturation. Intravascular rsIL-8 did not change fetal cardiovascular variables, blood pH, or blood leukocyte counts. Inhibition of CXCR2 decreased IA LPS-induced increases in BAL proteins at 1 day but not at 7 days. NTME did not significantly decrease IA LPS-induced BAL leukocyte influx and lung cytokine mRNA expression. Inhibition of CXCR2 did not change IA LPS-induced lung maturation. IL-8 signaling does not mediate LPS-induced lung inflammation and lung maturation.
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Affiliation(s)
- Suhas G Kallapur
- Cincinnati Children's Hospital Medical Center, University of Cincinnati, Division of Pulmonary Biology, 3333 Burnet Ave., Cincinnati, OH 45229-3039, USA.
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95
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Kallapur SG, Nitsos I, Moss TJM, Polglase GR, Pillow JJ, Cheah FC, Kramer BW, Newnham JP, Ikegami M, Jobe AH. IL-1 mediates pulmonary and systemic inflammatory responses to chorioamnionitis induced by lipopolysaccharide. Am J Respir Crit Care Med 2009; 179:955-61. [PMID: 19234101 DOI: 10.1164/rccm.200811-1728oc] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
RATIONALE Chorioamnionitis frequently associates with preterm delivery and increased amniotic fluid IL-1, and causes fetal lung and systemic inflammation. However, chorioamnionitis is also associated with a paradoxical reduction in the incidence of surfactant deficiency-related respiratory distress syndrome in preterm infants. OBJECTIVES To identify the role of IL-1 signaling in the mediation of pulmonary and systemic inflammation and lung maturation in a fetal sheep model of lipopolysaccharide (LPS) induced chorioamnionitis. METHODS After confirming the efficacy of recombinant human IL-1 receptor antagonist (rhIL-1ra), fetal sheep were exposed to intraamniotic (IA) injections of Escherichia coli LPS with or without prior IA injections of rhIL-1ra. Preterm lambs were delivered at 82% of term gestation. MEASUREMENTS AND MAIN RESULTS rhIL-1ra decreased IA LPS-induced lung inflammation assessed by decreased lung neutrophil and monocyte influx, inducible nitric oxide synthase expression, lung IL-6 and IL-1beta mRNA expression, and airway myeloperoxidase concentrations. rhIL-1ra inhibited IA LPS-induced fetal systemic inflammation assessed by decreased plasma IL-8, protein carbonyls, blood neutrophilia, and the expression of serum amyloid A3 mRNA in the liver. rhIL-1ra also partially blocked the lung maturational effects of IA LPS. Therefore blockade of IL-1 signaling in the amniotic compartment inhibited fetal lung and systemic inflammation and lung maturation in response to LPS-induced chorioamnionitis. CONCLUSIONS IL-1 plays a central role in the pathogenesis of chorioamnionitis-induced fetal inflammatory responses.
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Affiliation(s)
- Suhas G Kallapur
- Division of Pulmonary Biology, Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio, USA.
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96
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Chaiworapongsa T, Hong JS, Hull WM, Romero R, Whitsett JA. Amniotic fluid concentration of surfactant proteins in intra-amniotic infection. J Matern Fetal Neonatal Med 2009; 21:663-70. [PMID: 18828060 DOI: 10.1080/14767050802215664] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
OBJECTIVE Pulmonary surfactant is a complex molecule of lipids and proteins synthesized and secreted by type II alveolar cells into the alveolar epithelial lining. Both lipid and protein components are essential for lung function in postnatal life. Infection is a well-established cause of preterm delivery, and several inflammatory cytokines play a role in the mechanisms of preterm parturition. An increased concentration of inflammatory cytokines in amniotic fluid or fetal plasma has been linked to the onset of preterm parturition and fetal/neonatal injury, including cerebral palsy and chronic lung disease. Experimental evidence indicates that inflammatory mediators also regulate surfactant protein synthesis, and histologic chorioamnionitis is associated with a decreased incidence of hyaline membrane disease in neonates. This study was conducted to determine if amniotic fluid concentrations of surfactant protein (SP)-A, SP-B, and SP-D change in patients with and without intra-amniotic infection (IAI). MATERIALS AND METHODS A case-control study was conducted to determine amniotic fluid concentrations of SP-A, SP-B, SP-D, and total protein in patients who had an amniocentesis performed between 18 and 34 weeks of gestation for the detection of IAI in patients with spontaneous preterm labor with intact membranes (n = 42) and cervical insufficiency prior to the application of cerclage (n = 6). Amniotic fluid samples were selected from a bank of biological specimens and included patients with (n = 16) and without (n = 32) IAI matched for gestational age at amniocentesis. Intra-amniotic infection was defined as a positive amniotic fluid culture for microorganisms. Each group was further subdivided according to a history of corticosteroid administration within 7 days prior to amniocentesis into the following subgroups: (1) patients without IAI who had received antenatal corticosteroids (n = 21), (2) patients with IAI who had received antenatal corticosteroids (n = 9), (3) patients without IAI who had not received antenatal corticosteroids (n = 11), and (4) patients with IAI who had not received antenatal corticosteroids (n = 7). Amniotic fluid was obtained by transabdominal amniocentesis. SP-A, SP-B, and SP-D concentrations in amniotic fluid were determined by enzyme-linked immunosorbent assay (ELISA). Non-parametric statistics were used for analysis. RESULTS Women with IAI had a higher median amniotic fluid concentration of SP-B and of SP-B/total protein, but not other SPs, than those without IAI (both p = 0.03). Among patients who had received antenatal corticosteroids, the median amniotic fluid concentration of SP-B and of SP-B/total protein was significantly higher in patients with IAI than in those without IAI (SP-B, IAI: median 148 ng/mL, range 37.3-809 ng/mL vs. without IAI: median 7.2 ng/mL, range 0-1035 ng/mL; p = 0.005 and SP-B/total protein, IAI: median 14.1 ng/mg, range 4.3-237.5 ng/mg vs. without IAI: median 1.45 ng/mg, range 0-79.5 ng/mg; p = 0.003). Among women who had not received antenatal corticosteroids, the median amniotic fluid concentrations of SP-B and of SP-B/total protein were not significantly different between patients with and without IAI (SP-B, IAI: median 4 ng/mL, range 0-31.4 ng/mL vs. without IAI: median 3.4 ng/mL, range 0-37 ng/mL; p = 0.8 and SP-B/total protein, IAI: median 0.55 ng/mg, range 0-6.96 ng/mg vs. without IAI: median 0.59 ng/mg, range 0-3.28 ng/mg; p = 0.9). The median amniotic fluid concentrations of SP-A, SP-A/total protein, SP-D, and SP-D/total protein were not significantly different between patients with and without IAI whether they received antenatal corticosteroids or not (all p > 0.05). CONCLUSIONS IAI was associated with an increased amniotic fluid concentration of SP-B in patients who received antenatal corticosteroids within 7 days prior to amniocentesis.
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97
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Lee J, Seong HS, Kim BJ, Jun JK, Romero R, Yoon BH. Evidence to support that spontaneous preterm labor is adaptive in nature: neonatal RDS is more common in "indicated" than in "spontaneous" preterm birth. J Perinat Med 2009; 37:53-8. [PMID: 19099368 PMCID: PMC2887663 DOI: 10.1515/jpm.2009.036] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
OBJECTIVES The onset of preterm labor has been proposed to have survival value and to be adaptive in nature. This hypothesis would predict that induced preterm birth may be associated with higher rates of complications than spontaneous preterm birth. The purpose of this study was to determine if there is a difference in the frequency of neonatal respiratory distress syndrome (RDS), the most common neonatal complication, according to the etiology of preterm birth (e.g., preterm labor [PTL], preterm PROM, or pregnancies which ended because of maternal-fetal indications). STUDY DESIGN The relationship between the occurrence of RDS and the obstetrical circumstances leading to preterm birth was examined in 257 consecutive singleton preterm births (gestational age: 24-32 weeks). Cases with major congenital anomalies were excluded. The study population was divided into two groups according to the cause of preterm birth: 1) preterm birth due to PTL with intact membranes or preterm PROM (spontaneous preterm birth group); and 2) preterm birth due to maternal or fetal indications (indicated preterm birth group). RESULTS 1) RDS was diagnosed in 47% of cases; 2) RDS was more common in patients with indicated preterm birth than in those with spontaneous preterm birth group (58.1% vs. 38.4%, P=0.002); 3) Patients with indicated preterm birth had a significantly higher mean gestational age at birth, but lower mean birth weight, lower rate of histological chorioamnionitis and higher rates of cesarean delivery, 5 min Apgar score of <7, and umbilical arterial blood pH of <7.15 than those with spontaneous preterm birth (P<0.05 for each); 4) Antenatal corticosteroids were used in 73.4% of cases with indicated preterm birth and in 76.9% of those with spontaneous preterm birth; 5) Multivariate analysis demonstrated that indicated preterm birth was associated with an increased risk of RDS after adjusting for confounding variables (OR=2.29, 95% CI 1.22-4.29). CONCLUSIONS 1) The rate of RDS is greater following "indicated" rather than spontaneous preterm birth; 2) This observation supports the view that spontaneous preterm labor is adaptive in nature.
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Affiliation(s)
- Joonho Lee
- Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul, Korea
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Moss TJ, Nitsos I, Knox CL, Polglase GR, Kallapur SG, Ikegami M, Jobe AH, Newnham JP. Ureaplasma colonization of amniotic fluid and efficacy of antenatal corticosteroids for preterm lung maturation in sheep. Am J Obstet Gynecol 2009; 200:96.e1-6. [PMID: 19121661 DOI: 10.1016/j.ajog.2008.08.044] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2008] [Revised: 05/27/2008] [Accepted: 08/20/2008] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The objective of the study was to assess the efficacy of maternal betamethasone for improving preterm lung function in the presence of inflammation induced by amniotic fluid Ureaplasma colonization. STUDY DESIGN Ewes bearing single fetuses were randomized to receive an intraamniotic injection of Ureaplasma parvum (serovar 6; 2 x 10(7) colony-forming units) or vehicle at 86 +/- 2 days of pregnancy (mean +/- SD: term is 150 days), followed by maternal intramuscular betamethasone (0.5 mg/kg) or saline, either 2 or 7 days before delivery of lambs at 123 +/- 1 d. RESULTS Amniotic fluid interleukin-8 was elevated by ureaplasmas (P = .049) but unaffected by betamethasone. Lung inflammation induced by ureaplasmas was not affected by betamethasone. Lung compliance was increased by Ureaplasma colonization (P = .009) and betamethasone (P = .042), and effects were additive. Lung surfactant was increased by Ureaplasma colonization (P < .001) and betamethasone 7 days (P = .001), but not 2 days, before delivery. CONCLUSION Inflammation improves preterm lung function because of increases in surfactant. Antenatal corticosteroids further augment lung function through an apparently independent mechanism.
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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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100
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Ball MK, Jobe AH, Polglase GR, Kallapur SG, Cheah FC, Hillman NH, Pillow JJ. High and low body temperature during the initiation of ventilation for near-term lambs. Resuscitation 2008; 80:133-7. [PMID: 19013704 DOI: 10.1016/j.resuscitation.2008.10.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Revised: 09/24/2008] [Accepted: 10/02/2008] [Indexed: 10/21/2022]
Abstract
AIMS Recent literature suggests hypothermia may protect against lung injury. We evaluated body temperature as a variable in lung inflammation due to oxygenation and mechanical ventilation following delivery of near-term lambs. METHODS Twin fetuses were randomized prior to delivery at 140 d GA (term 150 d): unventilated controls, normothermic ventilated with room air, normothermic ventilated with 100% oxygen, low temperature ventilated (target 35 degrees C) with 100% oxygen, and high temperature (target 40 degrees C) with 100% oxygen. Lambs were intubated for gentle mechanical ventilation (tidal volume 7-8ml/kg). Temperature targeting was with radiant warmers and plastic wrap for normothermia, with heat lamps for hyperthermia, and with ice packs for hypothermia. Lambs were euthanized after 2h mechanical ventilation. Post-mortem, bronchoalveolar lavage fluid and lung tissue samples were evaluated for inflammatory responses by measuring inflammatory cell counts, protein, myeloperoxidase, protein carbonyl, and pro-inflammatory cytokine mRNA. RESULTS Target temperatures were achieved by 30min of age and tightly maintained for the 2h study. There were no differences in physiologic variables among groups except those directly resulting from study protocol-PaO2 from air vs. 100% oxygen and body temperature. Indicators of inflammation increased similarly in all ventilated groups compared to unventilated controls. CONCLUSION Moderate hyperthermia or hypothermia did not affect lung injury responses to the initiation of ventilation at birth in near-term lambs.
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Affiliation(s)
- Molly K Ball
- Cincinnati Children's Hospital Medical Center, Division of Pulmonary Biology, University of Cincinnati, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, USA
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