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Perlman CE, Knudsen L, Smith BJ. The fix is not yet in: recommendation for fixation of lungs within physiological/pathophysiological volume range in preclinical pulmonary structure-function studies. Am J Physiol Lung Cell Mol Physiol 2024; 327:L218-L231. [PMID: 38712433 PMCID: PMC11444500 DOI: 10.1152/ajplung.00341.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 02/14/2024] [Accepted: 04/22/2024] [Indexed: 05/08/2024] Open
Abstract
Quantitative characterization of lung structures by morphometrical or stereological analysis of histological sections is a powerful means of elucidating pulmonary structure-function relations. The overwhelming majority of studies, however, fix lungs for histology at pressures outside the physiological/pathophysiological respiratory volume range. Thus, valuable information is being lost. In this perspective article, we argue that investigators performing pulmonary histological studies should consider whether the aims of their studies would benefit from fixation at functional transpulmonary pressures, particularly those of end-inspiration and end-expiration. We survey the pressures at which lungs are typically fixed in preclinical structure-function studies, provide examples of conditions that would benefit from histological evaluation at functional lung volumes, summarize available fixation methods, discuss alternative imaging modalities, and discuss challenges to implementing the suggested approach and means of addressing those challenges. We aim to persuade investigators that modifying or complementing the traditional histological approach by fixing lungs at minimal and maximal functional volumes could enable new understanding of pulmonary structure-function relations.
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Affiliation(s)
- Carrie E Perlman
- Department of Biomedical Engineering, Stevens Institute of Technology, Hoboken, New Jersey, United States
| | - Lars Knudsen
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hannover, Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research (DZL), Hannover, Germany
| | - Bradford J Smith
- Department of Bioengineering, University of Colorado Denver | Anschutz Medical Campus, Aurora, Colorado, United States
- Section of Pulmonary and Sleep Medicine, Department of Pediatrics, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado, United States
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2
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Pulmonary Oxygen Exchange in a Rhythmically Expanding–Contracting Alveolus–Capillary Model. JOURNAL OF RESPIRATION 2022. [DOI: 10.3390/jor2040015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Pulmonary gas exchanges are vital to human health, and disruptions to this process have been associated with many respiratory diseases. Previous gas exchange studies have predominately relied on whole-body testing and theoretical analysis with 1D or static models. However, pulmonary gas exchanges are inherently a dynamic process in 3D spaces with instantaneous interactions between air, blood, and tissue. This study aimed to develop a computational model for oxygen exchange that considered all factors mentioned above. Therefore, an integrated alveolus–membrane–capillary geometry was developed with prescribed rhythmic expansion/contraction. Airflow ventilation, blood perfusion, and oxygen diffusion were simulated using COMSOL. The temporal and spatial distribution of blood flow and oxygen within the capillaries were simulated under varying breathing depths and cardiac outputs. The results showed highly nonuniform blood flow distributions in the capillary network, while the rhythmic oscillation further increased this nonuniformity, leading to stagnant blood flow in the distal vessels. A static alveolus–capillary geometry underestimated perfusion by 11% for normal respirations, and the deviation grew with breathing depth. The rhythmic motion caused a phase lag in the blood flow. The blood PO2 reached equilibrium with the alveolar air after traveling 1/5–1/3 of the capillary network. The time to reach this equilibrium was significantly influenced by the air–blood barrier diffusivity, while it was only slightly affected by the perfusion rate. The computational platform in this study could be instrumental in obtaining refined knowledge of pulmonary O2 exchanges.
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3
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Di Filippo P, Dodi G, Di Pillo S, Chiarelli F, Attanasi M. Effect of Invasive Mechanical Ventilation at Birth on Lung Function Later in Childhood. Front Pediatr 2022; 10:912057. [PMID: 35844745 PMCID: PMC9279909 DOI: 10.3389/fped.2022.912057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Accepted: 05/30/2022] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Despite recent neonatal care improvements, mechanical ventilation still remains a major cause of lung injury and inflammation. There is growing literature on short- and long-term respiratory outcomes in infants born prematurely in the post-surfactant era, but the exclusive role of mechanical ventilation at birth in lung function impairment is still unclear. The aim of this study was to assess the effect of neonatal mechanical ventilation on lung function parameters in children born ≤ 32 weeks of gestational age at 11 years of age. MATERIALS AND METHODS In total, 55 ex-preterm children born between January 1, 2006 and December 31, 2007 were enrolled at 11 years of age. Neonatal information was obtained from medical records. Information about family and personal clinical history was collected by questionnaires. At 11 years of age, we measured spirometry parameters, lung volumes, diffusing lung capacity, and fractional exhaled nitric oxide. In addition, an allergy evaluation by skin prick test and eosinophil blood count were performed. A multivariable linear or logistic regression analysis was performed to examine the associations of mechanical ventilation with respiratory outcomes, adjusting for confounders (maternal smoking during pregnancy, gestational age, surfactant replacement therapy, and BMI). RESULTS No difference in lung function evaluation between ventilated and unventilated children were found. No association was also found between mechanical ventilation with lung function parameters. CONCLUSION Mechanical ventilation for a short period at birth in preterm children was not associated with lung function impairment at 11 years of age in our study sample. It remains to define if ventilation may have a short-term effect on lung function, not evident at 11 years of age.
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Affiliation(s)
- Paola Di Filippo
- Pediatric Allergy and Respiratory Unit, Department of Pediatrics, University of Chieti, Chieti, Italy
| | - Giulia Dodi
- Pediatric Allergy and Respiratory Unit, Department of Pediatrics, University of Chieti, Chieti, Italy
| | - Sabrina Di Pillo
- Pediatric Allergy and Respiratory Unit, Department of Pediatrics, University of Chieti, Chieti, Italy
| | - Francesco Chiarelli
- Pediatric Allergy and Respiratory Unit, Department of Pediatrics, University of Chieti, Chieti, Italy
| | - Marina Attanasi
- Pediatric Allergy and Respiratory Unit, Department of Pediatrics, University of Chieti, Chieti, Italy
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4
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House M, Nathan A, Bhuiyan MAN, Ahlfeld SK. Morbidity and respiratory outcomes in infants requiring tracheostomy for severe bronchopulmonary dysplasia. Pediatr Pulmonol 2021; 56:2589-2596. [PMID: 34002957 DOI: 10.1002/ppul.25455] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 04/23/2021] [Accepted: 04/26/2021] [Indexed: 11/06/2022]
Abstract
OBJECTIVE The decision for tracheostomy for bronchopulmonary dysplasia (BPD) is highly variable and often dictated by local practice. We aimed to characterize morbidity, mortality, and respiratory outcomes in preterm infants undergoing tracheostomy for severe BPD. STUDY DESIGN We retrospectively reviewed a single-center 4-year cohort of all infants born <33 weeks gestational age (GA) that required tracheostomy due to severe BPD. Indications for tracheostomy apart from BPD were excluded. Demographic information, comorbidities, respiratory management, age at tracheostomy, post-discharge respiratory outcomes, and survival were examined up to at least 5 years of age. RESULTS At a mean corrected GA of 43.3 weeks, 49 preterm infants with severe BPD required tracheostomy. Forty-six infants (94%) had long-term follow-up. Compared to survivors, the 12 (26.1%) infants that died were significantly more likely to be small for gestational age (SGA) or require treatment for pulmonary hypertension. GA, birth weight, sex, antenatal corticosteroid exposure, need for patent ductus arteriosus ligation, and magnitude of respiratory support at tracheostomy placement were not associated with mortality. At the latest follow-up, 97% were liberated from mechanical ventilation and 79% decannulated. Morbidities of the upper airway were common, and 13/27 (47%) decannulated infants had required airway reconstruction. CONCLUSION Preterm infants undergoing tracheostomy experienced significant mortality, particularly those who were SGA or had pulmonary hypertension. However, by 5 years of age, most infants liberalized from mechanical ventilation and decannulated. Magnitude of respiratory support at time of tracheostomy was not associated with mortality and should not deter intervention. Nearly half of patients required airway reconstruction before decannulation.
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Affiliation(s)
- Melissa House
- Division of Neonatology and Pulmonary Biology, Perinatal Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.,Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Amy Nathan
- Division of Neonatology and Pulmonary Biology, Perinatal Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.,Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | | | - Shawn K Ahlfeld
- Division of Neonatology and Pulmonary Biology, Perinatal Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.,Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
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5
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Dylag AM, Raffay TM. Rodent models of respiratory control and respiratory system development-Clinical significance. Respir Physiol Neurobiol 2019; 268:103249. [PMID: 31315068 DOI: 10.1016/j.resp.2019.06.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 05/24/2019] [Accepted: 06/29/2019] [Indexed: 01/13/2023]
Abstract
The newborn infant's respiratory system must rapidly adapt to extra-uterine life. Neonatal rat and mouse models have been used to investigate early development of respiratory control and reactivity in both health and disease. This review highlights several rodent models of control of breathing and respiratory system development (including pulmonary function), discusses their translational strengths and limitations, and underscores the importance of creating clinically relevant models applicable to the human infant.
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Affiliation(s)
- Andrew M Dylag
- Division of Neonatology, Golisano Children's Hospital, Department of Pediatrics, University of Rochester, Rochester, NY, United States
| | - Thomas M Raffay
- Division of Neonatology, Rainbow Babies & Children's Hospital, Department of Pediatrics, Case Western Reserve University, Cleveland, OH, United States.
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6
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Koutsogiannaki S, Shimaoka M, Yuki K. The Use of Volatile Anesthetics as Sedatives for Acute Respiratory Distress Syndrome. ACTA ACUST UNITED AC 2019; 6:27-38. [PMID: 30923729 PMCID: PMC6433148 DOI: 10.31480/2330-4871/084] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Acute respiratory distress syndrome (ARDS) remains to pose a high morbidity and mortality without any targeted therapies. Sedation, usually given intravenously, is an important part of clinical practice in intensive care unit (ICU), and the effect of sedatives on patients’ outcomes has been studied intensively. Although volatile anesthetics are not routine sedatives in ICU, preclinical and clinical studies suggested their potential benefit in pulmonary pathophysiology. This review will summarize the current knowledge of ARDS and the role of volatile anesthetic sedation in this setting from both clinical and mechanistic standpoints. In addition, we will review the infrastructure to use volatile anesthetics.
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Affiliation(s)
- Sophia Koutsogiannaki
- Department of Anaesthesia, Harvard Medical School, Boston, Massachusetts, USA.,Department of Anesthesiology, Critical Care and Pain Medicine, Cardiac Anesthesia Division, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Motomu Shimaoka
- Department of Molecular Pathobiology and Cell Adhesion Biology, Mie University Graduate School of Medicine, Tsushi, Mie, Japan
| | - Koichi Yuki
- Department of Anaesthesia, Harvard Medical School, Boston, Massachusetts, USA.,Department of Anesthesiology, Critical Care and Pain Medicine, Cardiac Anesthesia Division, Boston Children's Hospital, Boston, Massachusetts, USA
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7
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Oakley RB, Tingay DG, McCall KE, Perkins EJ, Sourial M, Dargaville PA, Pereira-Fantini PM. Gestational Age Influences the Early Microarchitectural Changes in Response to Mechanical Ventilation in the Preterm Lamb Lung. Front Pediatr 2019; 7:325. [PMID: 31497582 PMCID: PMC6712425 DOI: 10.3389/fped.2019.00325] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 07/19/2019] [Indexed: 11/13/2022] Open
Abstract
Background: Preterm birth is associated with abnormal lung architecture, and a reduction in pulmonary function related to the degree of prematurity. A thorough understanding of the impact of gestational age on lung microarchitecture requires reproducible quantitative analysis of lung structure abnormalities. The objectives of this study were (1) to use quantitative histological software (ImageJ) to map morphological patterns of injury resulting from delivery of an identical ventilation strategy to the lung at varying gestational ages and (2) to identify associations between gestational age-specific morphological alterations and key functional outcomes. Method: Lung morphology was compared after 60 min of a standardized ventilation protocol (40 cm H2O sustained inflation and then volume-targeted positive pressure ventilation with positive end-expiratory pressure 8 cm H2O) in lambs at different gestations (119, 124, 128, 133, 140d) representing the spectrum of premature developmental lung states and the term lung. Age-matched controls were compared at 124 and 128d gestation. Automated and manual functions of Image J were used to measure key histological features. Correlation analysis compared morphological and functional outcomes in lambs aged ≤128 and >128d. Results: In initial studies, unventilated lung was indistinguishable at 124 and 128d. Ventilated lung from lambs aged 124d gestation exhibited increased numbers of detached epithelial cells and lung tissue compared with 128d lambs. Comparing results from saccular to alveolar development (120-140d), lambs aged ≤124d exhibited increased lung tissue, average alveolar area, and increased numbers of detached epithelial cells. Alveolar septal width was increased in lambs aged ≤128d. These findings were mirrored in the measures of gas exchange, lung mechanics, and molecular markers of lung injury. Correlation analysis confirmed the gestation-specific relationships between the histological assessments and functional measures in ventilated lambs at gestation ≤128 vs. >128d. Conclusion: Image J allowed rapid, quantitative assessment of alveolar morphology, and lung injury in the preterm lamb model. Gestational age-specific patterns of injury in response to delivery of an identical ventilation strategy were identified, with 128d being a transition point for associations between morphological alterations and functional outcomes. These results further support the need to develop individualized respiratory support approaches tailored to both the gestational age of the infant and their underlying injury response.
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Affiliation(s)
- Regina B Oakley
- Neonatal Research Group, Murdoch Children's Research Institute, Parkville, VIC, Australia
| | - David G Tingay
- Neonatal Research Group, Murdoch Children's Research Institute, Parkville, VIC, Australia.,Department of Neonatology, Royal Children's Hospital, Parkville, VIC, Australia.,Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia
| | - Karen E McCall
- Neonatal Research Group, Murdoch Children's Research Institute, Parkville, VIC, Australia.,School of Medicine and Medicinal Sciences, University College Dublin, Dublin, Ireland
| | - Elizabeth J Perkins
- Neonatal Research Group, Murdoch Children's Research Institute, Parkville, VIC, Australia
| | - Magdy Sourial
- Neonatal Research Group, Murdoch Children's Research Institute, Parkville, VIC, Australia
| | - Peter A Dargaville
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS, Australia
| | - Prue M Pereira-Fantini
- Neonatal Research Group, Murdoch Children's Research Institute, Parkville, VIC, Australia.,Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia
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8
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Cheon IS, Son YM, Jiang L, Goplen NP, Kaplan MH, Limper AH, Kita H, Paczesny S, Prakash YS, Tepper R, Ahlfeld SK, Sun J. Neonatal hyperoxia promotes asthma-like features through IL-33-dependent ILC2 responses. J Allergy Clin Immunol 2018; 142:1100-1112. [PMID: 29253513 PMCID: PMC6003836 DOI: 10.1016/j.jaci.2017.11.025] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 11/06/2017] [Accepted: 11/24/2017] [Indexed: 12/19/2022]
Abstract
BACKGROUND Premature infants often require oxygen supplementation and, therefore, are exposed to oxidative stress. Following oxygen exposure, preterm infants frequently develop chronic lung disease and have a significantly increased risk of asthma. OBJECTIVE We sought to identify the underlying mechanisms by which neonatal hyperoxia promotes asthma development. METHODS Mice were exposed to neonatal hyperoxia followed by a period of room air recovery. A group of mice was also intranasally exposed to house dust mite antigen. Assessments were performed at various time points for evaluation of airway hyperresponsiveness, eosinophilia, mucus production, inflammatory gene expression, and TH and group 2 innate lymphoid cell (ILC2) responses. Sera from term- and preterm-born infants were also collected and levels of IL-33 and type 2 cytokines were measured. RESULTS Neonatal hyperoxia induced asthma-like features including airway hyperresponsiveness, mucus hyperplasia, airway eosinophilia, and type 2 pulmonary inflammation. In addition, neonatal hyperoxia promoted allergic TH responses to house dust mite exposure. Elevated IL-33 levels and ILC2 responses were observed in the lungs most likely due to oxidative stress caused by neonatal hyperoxia. IL-33 receptor signaling and ILC2s were vital for the induction of asthma-like features following neonatal hyperoxia. Serum IL-33 levels correlated significantly with serum levels of IL-5 and IL-13 but not IL-4 in preterm infants. CONCLUSIONS These data demonstrate that an axis involving IL-33 and ILC2s is important for the development of asthma-like features following neonatal hyperoxia and suggest therapeutic potential for targeting IL-33, ILC2s, and oxidative stress to prevent and/or treat asthma development related to prematurity.
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Affiliation(s)
- In Su Cheon
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Ind; Division of Pulmonary and Critical Care Medicine, Department of Medicine, Mayo Clinic College of Medicine and Science, Rochester, Minn
| | - Young Min Son
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Ind; Division of Pulmonary and Critical Care Medicine, Department of Medicine, Mayo Clinic College of Medicine and Science, Rochester, Minn
| | - Li Jiang
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Ind; Division of Pulmonary and Critical Care Medicine, Department of Medicine, Mayo Clinic College of Medicine and Science, Rochester, Minn
| | - Nicholas P Goplen
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Mayo Clinic College of Medicine and Science, Rochester, Minn
| | - Mark H Kaplan
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Ind
| | - Andrew H Limper
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Mayo Clinic College of Medicine and Science, Rochester, Minn
| | - Hirohito Kita
- Department of Immunology, Mayo Clinic College of Medicine and Science, Rochester, Minn
| | - Sophie Paczesny
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Ind
| | - Y S Prakash
- Department of Anesthesiology, Mayo Clinic College of Medicine and Science, Rochester, Minn; Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minn
| | - Robert Tepper
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Ind
| | - Shawn K Ahlfeld
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Ind; Department of Pediatrics, University of Cincinnati, Cincinnati, Ohio
| | - Jie Sun
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Ind; Division of Pulmonary and Critical Care Medicine, Department of Medicine, Mayo Clinic College of Medicine and Science, Rochester, Minn; Department of Immunology, Mayo Clinic College of Medicine and Science, Rochester, Minn.
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9
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Cox AM, Gao Y, Perl AKT, Tepper RS, Ahlfeld SK. Cumulative effects of neonatal hyperoxia on murine alveolar structure and function. Pediatr Pulmonol 2017; 52:616-624. [PMID: 28186703 PMCID: PMC5621136 DOI: 10.1002/ppul.23654] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 11/07/2016] [Accepted: 11/23/2016] [Indexed: 12/23/2022]
Abstract
BACKGROUND Bronchopulmonary dysplasia (BPD) results from alveolar simplification and abnormal development of alveolar and capillary structure. Survivors of BPD display persistent deficits in airflow and membrane and vascular components of alveolar gas diffusion. Despite being the defining feature of BPD, various neonatal hyperoxia models of BPD have not routinely assessed pulmonary gas diffusion. METHODS To simulate the most commonly-utilized neonatal hyperoxia models, we exposed neonatal mice to room air or ≥90% hyperoxia during key stages of distal lung development: through the first 4 (saccular), 7 (early alveolar), or 14 (bulk alveolar) postnatal days, followed by a period of recovery in room air until 8 weeks of age when alveolar septation is essentially complete. We systematically assessed and correlated the effects of neonatal hyperoxia on the degree of alveolar-capillary structural and functional impairment. We hypothesized that the degree of alveolar-capillary simplification would correlate strongly with worsening diffusion impairment. RESULTS Neonatal hyperoxia exposure, of any duration, resulted in alveolar simplification and impaired pulmonary gas diffusion. Mean Linear Intercept increased in proportion to the length of hyperoxia exposure while alveolar and total lung volume increased markedly only with prolonged exposure. Surprisingly, despite having a similar effect on alveolar surface area, only prolonged hyperoxia for 14 days resulted in reduced pulmonary microvascular volume. Estimates of alveolar and capillary structure, in general, correlated poorly with assessment of gas diffusion. CONCLUSION Our results help define the physiological and structural consequences of commonly-employed neonatal hyperoxia models of BPD and inform their clinical utility. Pediatr Pulmonol. 2017;52:616-624. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Angela M. Cox
- Program in Developmental Biology and Neonatal Medicine, Herman B Wells Center for Pediatric Research, Indianapolis, Indiana
- Division of Neonatology, James Whitcomb Riley Hospital for Children, Indiana University School of Medicine, Indianapolis, Indiana
| | - Yong Gao
- Program in Developmental Biology and Neonatal Medicine, Herman B Wells Center for Pediatric Research, Indianapolis, Indiana
- Program in Pulmonary Inflammation, Asthma and Allergic Diseases, Herman B Wells Center for Pediatric Research, Indianapolis, Indiana
| | - Anne-Karina T. Perl
- Division of Neonatology, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio
- Division of Pulmonary Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio
| | - Robert S. Tepper
- Program in Pulmonary Inflammation, Asthma and Allergic Diseases, Herman B Wells Center for Pediatric Research, Indianapolis, Indiana
- Division of Pulmonary Medicine, Department of Pediatrics, James Whitcomb Riley Hospital for Children, Indiana University School of Medicine, Indianapolis, Indiana
| | - Shawn K. Ahlfeld
- Division of Neonatology, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio
- Division of Pulmonary Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio
- Correspondence to: Shawn K. Ahlfeld, MD, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Ave, MLC 7009, Cincinnati, OH 45229.
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10
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Afacan O, Gholipour A, Mulkern RV, Barnewolt CE, Estroff JA, Connolly SA, Parad RB, Bairdain S, Warfield SK. Fetal lung apparent diffusion coefficient measurement using diffusion-weighted MRI at 3 Tesla: Correlation with gestational age. J Magn Reson Imaging 2016; 44:1650-1655. [PMID: 27159847 DOI: 10.1002/jmri.25294] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Revised: 04/08/2016] [Accepted: 04/10/2016] [Indexed: 11/09/2022] Open
Abstract
PURPOSE To evaluate the feasibility of using diffusion-weighted magnetic resonance imaging (DW-MRI) to assess the fetal lung apparent diffusion coefficient (ADC) at 3 Tesla (T). MATERIALS AND METHODS Seventy-one pregnant women (32 second trimester, 39 third trimester) were scanned with a twice-refocused Echo-planar diffusion-weighted imaging sequence with 6 different b-values in 3 orthogonal diffusion orientations at 3T. After each scan, a region-of-interest (ROI) mask was drawn to select a region in the fetal lung and an automated robust maximum likelihood estimation algorithm was used to compute the ADC parameter. The amount of motion in each scan was visually rated. RESULTS When scans with unacceptable levels of motion were eliminated, the lung ADC values showed a strong association with gestational age (P < 0.01), increasing dramatically between 16 and 27 weeks and then achieving a plateau around 27 weeks. CONCLUSION We show that to get reliable estimates of ADC values of fetal lungs, a multiple b-value acquisition, where motion is either corrected or considered, can be performed. J. Magn. Reson. Imaging 2016;44:1650-1655.
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Affiliation(s)
- Onur Afacan
- Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA
| | - Ali Gholipour
- Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA
| | - Robert V Mulkern
- Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA
| | - Carol E Barnewolt
- Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA.,Advanced Fetal Care Center, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Judy A Estroff
- Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA.,Advanced Fetal Care Center, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Susan A Connolly
- Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA.,Advanced Fetal Care Center, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Richard B Parad
- Advanced Fetal Care Center, Boston Children's Hospital, Boston, Massachusetts, USA.,Department of Pediatric Newborn Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Sigrid Bairdain
- Harvard Medical School, Boston, Massachusetts, USA.,Department of Surgery, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Simon K Warfield
- Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA
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11
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Goss KN, Tepper RS, Lahm T, Ahlfeld SK. Increased Cardiac Output and Preserved Gas Exchange Despite Decreased Alveolar Surface Area in Rats Exposed to Neonatal Hyperoxia and Adult Hypoxia. Am J Respir Cell Mol Biol 2016; 53:902-6. [PMID: 26623969 DOI: 10.1165/rcmb.2015-0100le] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Kara N Goss
- 1 University of Wisconsin School of Medicine and Public Health Madison, Wisconsin
| | - Robert S Tepper
- 2 Indiana University School of Medicine Indianapolis, Indiana
| | - Tim Lahm
- 2 Indiana University School of Medicine Indianapolis, Indiana.,3 Richard L Roudebush VA Medical Center Indianapolis, Indiana
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12
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Ahlfeld SK, Wang J, Gao Y, Snider P, Conway SJ. Initial Suppression of Transforming Growth Factor-β Signaling and Loss of TGFBI Causes Early Alveolar Structural Defects Resulting in Bronchopulmonary Dysplasia. THE AMERICAN JOURNAL OF PATHOLOGY 2016; 186:777-93. [PMID: 26878215 DOI: 10.1016/j.ajpath.2015.11.024] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 11/02/2015] [Accepted: 11/18/2015] [Indexed: 12/22/2022]
Abstract
Septation of the gas-exchange saccules of the morphologically immature mouse lung requires regulated timing, spatial direction, and dosage of transforming growth factor (TGF)-β signaling. We found that neonatal hyperoxia acutely initially diminished saccular TGF-β signaling coincident with alveolar simplification. However, sustained hyperoxia resulted in a biphasic response and subsequent up-regulation of TGF-β signaling, ultimately resulting in bronchopulmonary dysplasia. Significantly, we found that the TGF-β-induced matricellular protein (TGFBI) was similarly biphasically altered in response to hyperoxia. Moreover, genetic ablation revealed that TGFBI was required for normal alveolar structure and function. Although the phenotype was not neonatal lethal, Tgfbi-deficient lungs were morphologically abnormal. Mutant septal tips were stunted, lacked elastin-positive tips, exhibited reduced proliferation, and contained abnormally persistent alveolar α-smooth muscle actin myofibroblasts. In addition, Tgfbi-deficient lungs misexpressed TGF-β-responsive follistatin and serpine 1, and transiently suppressed myofibroblast platelet-derived growth factor α differentiation marker. Finally, despite normal lung volume, Tgfbi-null lungs displayed diminished elastic recoil and gas exchange efficiency. Combined, these data demonstrate that initial suppression of the TGF-β signaling apparatus, as well as loss of key TGF-β effectors (like TGFBI), underlies early alveolar structural defects, as well as long-lasting functional deficits routinely observed in chronic lung disease of infancy patients. These studies underline the complex (and often contradictory) role of TGF-β and indicate a need to design studies to associate alterations with initial appearance of phenotypical changes suggestive of bronchopulmonary dysplasia.
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Affiliation(s)
- Shawn K Ahlfeld
- HB Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
| | - Jian Wang
- HB Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
| | - Yong Gao
- HB Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
| | - Paige Snider
- HB Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
| | - Simon J Conway
- HB Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana.
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Goss KN, Cucci AR, Fisher AJ, Albrecht M, Frump A, Tursunova R, Gao Y, Brown MB, Petrache I, Tepper RS, Ahlfeld SK, Lahm T. Neonatal hyperoxic lung injury favorably alters adult right ventricular remodeling response to chronic hypoxia exposure. Am J Physiol Lung Cell Mol Physiol 2015; 308:L797-806. [PMID: 25659904 DOI: 10.1152/ajplung.00276.2014] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 02/06/2015] [Indexed: 11/22/2022] Open
Abstract
The development of pulmonary hypertension (PH) requires multiple pulmonary vascular insults, yet the role of early oxygen therapy as an initial pulmonary vascular insult remains poorly defined. Here, we employ a two-hit model of PH, utilizing postnatal hyperoxia followed by adult hypoxia exposure, to evaluate the role of early hyperoxic lung injury in the development of later PH. Sprague-Dawley pups were exposed to 90% oxygen during postnatal days 0-4 or 0-10 or to room air. All pups were then allowed to mature in room air. At 10 wk of age, a subset of rats from each group was exposed to 2 wk of hypoxia (Patm = 362 mmHg). Physiological, structural, and biochemical endpoints were assessed at 12 wk. Prolonged (10 days) postnatal hyperoxia was independently associated with elevated right ventricular (RV) systolic pressure, which worsened after hypoxia exposure later in life. These findings were only partially explained by decreases in lung microvascular density. Surprisingly, postnatal hyperoxia resulted in robust RV hypertrophy and more preserved RV function and exercise capacity following adult hypoxia compared with nonhyperoxic rats. Biochemically, RVs from animals exposed to postnatal hyperoxia and adult hypoxia demonstrated increased capillarization and a switch to a fetal gene pattern, suggesting an RV more adept to handle adult hypoxia following postnatal hyperoxia exposure. We concluded that, despite negative impacts on pulmonary artery pressures, postnatal hyperoxia exposure may render a more adaptive RV phenotype to tolerate late pulmonary vascular insults.
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Affiliation(s)
- Kara N Goss
- Division of Pulmonary, Allergy, Critical Care and Occupational Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Anthony R Cucci
- Division of Pulmonary, Allergy, Critical Care and Occupational Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Amanda J Fisher
- Department of Anesthesiology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Marjorie Albrecht
- Division of Pulmonary, Allergy, Critical Care and Occupational Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Andrea Frump
- Division of Pulmonary, Allergy, Critical Care and Occupational Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Roziya Tursunova
- Division of Pulmonary, Allergy, Critical Care and Occupational Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Yong Gao
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana
| | - Mary Beth Brown
- Department of Physical Therapy, School of Health and Rehabilitation Sciences, Indiana University School of Medicine, Indianapolis, Indiana
| | - Irina Petrache
- Division of Pulmonary, Allergy, Critical Care and Occupational Medicine, Indiana University School of Medicine, Indianapolis, Indiana; Richard L. Roudebush VA Medical Center, Indianapolis, Indiana
| | - Robert S Tepper
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana
| | - Shawn K Ahlfeld
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana
| | - Tim Lahm
- Division of Pulmonary, Allergy, Critical Care and Occupational Medicine, Indiana University School of Medicine, Indianapolis, Indiana; Richard L. Roudebush VA Medical Center, Indianapolis, Indiana
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Relationship of structural to functional impairment during alveolar-capillary membrane development. THE AMERICAN JOURNAL OF PATHOLOGY 2015; 185:913-9. [PMID: 25661110 DOI: 10.1016/j.ajpath.2014.12.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 11/21/2014] [Accepted: 12/02/2014] [Indexed: 11/22/2022]
Abstract
Bronchopulmonary dysplasia is a chronic lung disease of extreme preterm infants and results in impaired gas exchange. Although bronchopulmonary dysplasia is characterized histologically by alveolar-capillary simplification in animal models, it is clinically defined by impaired gas diffusion. With the use of a developmentally relevant model, we correlated alveolar-capillary structural simplification with reduced functional gas exchange as measured by the diffusing factor for carbon monoxide (DFCO). Neonatal mouse pups were exposed to >90% hyperoxia or room air during postnatal days 0 to 7, and then all pups were returned to room air from days 7 to 56. At day 56, DFCO was measured as the ratio of carbon monoxide uptake to neon dilution, and lungs were fixed for histologic assessment of alveolar-capillary development. Neonatal hyperoxia exposure inhibited alveolar-capillary septal development as evidenced by significantly increased mean linear intercept, increased airspace-to-septal ratio, decreased nodal density, and decreased pulmonary microvasculature. Importantly, alveolar-capillary structural deficits in hyperoxia-exposed pups were accompanied by a significant 28% decrease in DFCO (0.555 versus 0.400; P < 0.0001). In addition, DFCO was highly and significantly correlated with structural measures of reduced alveolar-capillary growth. Simplification of alveolar-capillary structure is highly correlated with impaired gas exchange function. Current mechanistic and therapeutic animal models of inhibited alveolar development may benefit from application of DFCO as an alternative physiologic indicator of alveolar-capillary development.
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Abman SH, Conway SJ. Developmental determinants and changing patterns of respiratory outcomes after preterm birth. ACTA ACUST UNITED AC 2014; 100:127-33. [PMID: 24659395 DOI: 10.1002/bdra.23242] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Accepted: 03/06/2014] [Indexed: 12/27/2022]
Affiliation(s)
- Steven H Abman
- Pediatric Heart Lung Center, Pediatric Pulmonary Medicine, University of Colorado Anschutz Medical Center and Children's Hospital Colorado, Aurora, Colorado
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