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Balany J, Bhandari V. Understanding the Impact of Infection, Inflammation, and Their Persistence in the Pathogenesis of Bronchopulmonary Dysplasia. Front Med (Lausanne) 2015; 2:90. [PMID: 26734611 PMCID: PMC4685088 DOI: 10.3389/fmed.2015.00090] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 12/03/2015] [Indexed: 12/11/2022] Open
Abstract
The concerted interaction of genetic and environmental factors acts on the preterm human immature lung with inflammation being the common denominator leading to the multifactorial origin of the most common chronic lung disease in infants – bronchopulmonary dysplasia (BPD). Adverse perinatal exposure to infection/inflammation with added insults like invasive mecha nical ventilation, exposure to hyperoxia, and sepsis causes persistent immune dysregulation. In this review article, we have attempted to analyze and consolidate current knowledge about the role played by persistent prenatal and postnatal inflammation in the pathogenesis of BPD. While some parameters of the early inflammatory response (neutrophils, cytokines, etc.) may not be detectable after days to weeks of exposure to noxious stimuli, they have already initiated the signaling pathways of the inflammatory process/immune cascade and have affected permanent defects structurally and functionally in the BPD lungs. Hence, translational research aimed at prevention/amelioration of BPD needs to focus on dampening the inflammatory response at an early stage to prevent the cascade of events leading to lung injury with impaired healing resulting in the pathologic pulmonary phenotype of alveolar simplification and dysregulated vascularization characteristic of BPD.
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Affiliation(s)
- Jherna Balany
- Section of Neonatology, Department of Pediatrics, St. Christopher's Hospital for Children, Drexel University College of Medicine , Philadelphia, PA , USA
| | - Vineet Bhandari
- Section of Neonatology, Department of Pediatrics, St. Christopher's Hospital for Children, Drexel University College of Medicine , Philadelphia, PA , USA
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Kneyber MCJ, Zhang H, Slutsky AS. Ventilator-induced lung injury. Similarity and differences between children and adults. Am J Respir Crit Care Med 2014; 190:258-65. [PMID: 25003705 DOI: 10.1164/rccm.201401-0168cp] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
It is well established that mechanical ventilation can injure the lung, producing an entity known as ventilator-induced lung injury (VILI). There are various forms of VILI, including volutrauma (i.e., injury caused by overdistending the lung), atelectrauma (injury due to repeated opening/closing of lung units), and biotrauma (release of mediators that can induce lung injury or aggravate pre-existing injury, potentially leading to multiple organ failure). Experimental data in the pediatric context are in accord with the importance of VILI, and appear to show age-related susceptibility to VILI, although a conclusive link between use of large Vts and mortality has not been demonstrated in this population. The relevance of VILI in the pediatric intensive care unit population is thus unclear. Given the physiological and biological differences in the respiratory systems of infants, children, and adults, it is difficult to directly extrapolate clinical practice from adults to children. This Critical Care Perspective analyzes the relevance of VILI to the pediatric population, and addresses why pediatric patients might be less susceptible than adults to VILI.
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Affiliation(s)
- Martin C J Kneyber
- 1 Keenan Research Centre for Biomedical Science of St. Michael's Hospital, Toronto, Ontario, Canada
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Bhandari V. Postnatal inflammation in the pathogenesis of bronchopulmonary dysplasia. ACTA ACUST UNITED AC 2014; 100:189-201. [PMID: 24578018 DOI: 10.1002/bdra.23220] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 01/02/2014] [Accepted: 01/05/2014] [Indexed: 12/18/2022]
Abstract
Exposure to hyperoxia, invasive mechanical ventilation, and systemic/local sepsis are important antecedents of postnatal inflammation in the pathogenesis of bronchopulmonary dysplasia (BPD). This review will summarize information obtained from animal (baboon, lamb/sheep, rat and mouse) models that pertain to the specific inflammatory agents and signaling molecules that predispose a premature infant to BPD.
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Affiliation(s)
- Vineet Bhandari
- Division of Perinatal Medicine, Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut
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Sly PD, Nicholls PK, Berry LJ, Hantos Z, Cannizzaro V. High tidal volume ventilation does not exacerbate acid-induced lung injury in infant rats. Respir Physiol Neurobiol 2013; 189:129-35. [DOI: 10.1016/j.resp.2013.07.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 07/06/2013] [Accepted: 07/08/2013] [Indexed: 10/26/2022]
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Trummer-Menzi E, Gremlich S, Schittny JC, Dénervaud V, Stampanoni M, Post M, Gerber S, Roth-Kleiner M. Evolution of gene expression changes in newborn rats after mechanical ventilation with reversible intubation. Pediatr Pulmonol 2012; 47:1204-14. [PMID: 22782699 DOI: 10.1002/ppul.22613] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Accepted: 05/16/2012] [Indexed: 11/09/2022]
Abstract
Mechanical ventilation (MV) is life-saving but potentially harmful for lungs of premature infants. So far, animal models dealt with the acute impact of MV on immature lungs, but less with its delayed effects. We used a newborn rodent model including non-surgical and therefore reversible intubation with moderate ventilation and hypothesized that there might be distinct gene expression patterns after a ventilation-free recovery period compared to acute effects directly after MV. Newborn rat pups were subjected to 8 hr of MV with 60% oxygen (O(2)), 24 hr after injection of lipopolysaccharide (LPS), intended to create a low inflammatory background as often recognized in preterm infants. Animals were separated in controls (CTRL), LPS injection (LPS), or full intervention with LPS and MV with 60% O(2) (LPS + MV + O(2)). Lungs were recovered either directly following (T:0 hr) or 48 hr after MV (T:48 hr). Histologically, signs of ventilator-induced lung injury (VILI) were observed in LPS + MV + O(2) lungs at T:0 hr, while changes appeared similar to those known from patients with chronic lung disease (CLD) with fewer albeit larger gas exchange units, at T:48 hr. At T:0 hr, LPS + MV + O(2) increased gene expression of pro-inflammatory MIP-2. In parallel anti-inflammatory IL-1Ra gene expression was increased in LPS and LPS + MV + O(2) groups. At T:48 hr, pro- and anti-inflammatory genes had returned to their basal expression. MMP-2 gene expression was decreased in LPS and LPS + MV + O(2) groups at T:0 hr, but no longer at T:48 hr. MMP-9 gene expression levels were unchanged directly after MV. However, at T:48 hr, gene and protein expression increased in LPS + MV + O(2) group. In conclusion, this study demonstrates the feasibility of delayed outcome measurements after a ventilation-free period in newborn rats and may help to further understand the time-course of molecular changes following MV. The differences obtained from the two time points could be interpreted as an initial transitory increase of inflammation and a delayed impact of the intervention on structure-related genes.
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Affiliation(s)
- Eliane Trummer-Menzi
- Clinic of Neonatology, Department of Pediatrics, University Hospital (CHUV) and University of Lausanne, Lausanne, Switzerland
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The need for and feasibility of a pediatric ventilation trial: reflections on a survey among pediatric intensivists*. Pediatr Crit Care Med 2012; 13:632-8. [PMID: 22791089 DOI: 10.1097/pcc.0b013e31824fbc37] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To explore what design would be reasonable, acceptable, and feasible for a pediatric trial investigating the effect of low tidal volume ventilation. DESIGN A two-round modified Delphi approach among pediatric intensivists with a visible special interest in mechanical ventilation. SETTINGS None. SUBJECTS Pediatric intensivists. INTERVENTIONS None. MEASUREMENTS AND RESULTS In the first questionnaire "experts" classified 64 items as "important," "not so important" or "not important" (June 2010). The second questionnaire included the 29 items having been classified by more than 50% of the experts as being "important" in the first questionnaire that needed to be ranked in order of importance (August 2010). Twenty-nine of 50 (64%) experts responded to the first questionnaire, and 28 of the 29 initial responders (96.6%) to the second questionnaire. Actual expert opinion favored the following: age of study population 0 yrs to 2 yrs, expected duration of ventilation ≥ 48 hrs, and stratification by the severity of hypoxemia (cutoff PaO(2)/FIO(2) < 200). The two study arms should compare the effect of 6 mL/kg vs. 10 mL/kg on mortality. However, these views of the experts face two major issues. First, 10 mL/kg does not represent standard of care. Second, numerous uncertainties render mortality unsuitable as primary measure of outcome including a large sample size (>1500). CONCLUSIONS Actual expert opinion favored investigating the effect of 6 mL/kg vs.10 mL/kg on mortality. Such a design suffers from various serious criticisms. Therefore, and in our opinion, a pediatric Acute Respiratory Distress Syndrome Network trial is not realistic.
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High tidal volume ventilation is not deleterious in infant rats exposed to severe hemorrhage. ACTA ACUST UNITED AC 2010; 69:E24-31. [PMID: 20495489 DOI: 10.1097/ta.0b013e3181d7503c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Both high tidal volume (V(T)) ventilation and hemorrhage induce acute lung injury in adult rodents. It is not known whether injurious ventilation augments lung injury in infant rats exposed to severe hemorrhage. METHODS Two-week-old rats were allocated for ventilation with VT 7 mL/kg and positive end-expiratory pressure (PEEP) 5 cm H₂O (low V(T)) or V(T) 21 mL/kg and PEEP 1 (high V(T)) for 4 hours. Additional rats were subjected to volume-controlled hemorrhage and delayed saline resuscitation, followed by low V(T) or high V(T) ventilation for 4 hours. Nonventilated control groups were also included. Airway resistance and the coefficient of tissue elastance were derived from respiratory input impedance measurements using the low-frequency forced oscillation technique. Pressure-volume curves were obtained at baseline and at the end of the study. Interleukin-6, macrophage inflammatory protein-2, and tumor necrosis factor alpha were determined in bronchoalveolar lavage fluid (BALF) and serum. RESULTS In both healthy and hemorrhage-exposed animals, high V(T) resulted in reduced elastance (better lung compliance) and increased transcutaneous oxygen saturation. Interleukin-6 in BALF was greater in ventilated animals when compared with nonventilated controls, but not different among ventilated groups. No significant differences were found for all other inflammatory mediators, total protein concentration in BALF, and histology. CONCLUSION High V(T) ventilation with low PEEP improves respiratory system mechanics without causing additional damage to healthy and hemorrhage-exposed infant rats after 4 hours of ventilation. This study highlights the tolerance to high V(T) ventilation in infant rats and underscores the need for age-specific animal models.
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Cannizzaro V, Hantos Z, Sly PD, Zosky GR. Linking lung function and inflammatory responses in ventilator-induced lung injury. Am J Physiol Lung Cell Mol Physiol 2010; 300:L112-20. [PMID: 20952494 DOI: 10.1152/ajplung.00158.2010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Despite decades of research, the mechanisms of ventilator-induced lung injury are poorly understood. We used strain-dependent responses to mechanical ventilation in mice to identify associations between mechanical and inflammatory responses in the lung. BALB/c, C57BL/6, and 129/Sv mice were ventilated using a protective [low tidal volume and moderate positive end-expiratory pressure (PEEP) and recruitment maneuvers] or injurious (high tidal volume and zero PEEP) ventilation strategy. Lung mechanics and lung volume were monitored using the forced oscillation technique and plethysmography, respectively. Inflammation was assessed by measuring numbers of inflammatory cells, cytokine (IL-6, IL-1β, and TNF-α) levels, and protein content of the BAL. Principal components factor analysis was used to identify independent associations between lung function and inflammation. Mechanical and inflammatory responses in the lung were dependent on ventilation strategy and mouse strain. Three factors were identified linking 1) pulmonary edema, protein leak, and macrophages, 2) atelectasis, IL-6, and TNF-α, and 3) IL-1β and neutrophils, which were independent of responses in lung mechanics. This approach has allowed us to identify specific inflammatory responses that are independently associated with overstretch of the lung parenchyma and loss of lung volume. These data provide critical insight into the mechanical responses in the lung that drive local inflammation in ventilator-induced lung injury and the basis for future mechanistic studies in this field.
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Affiliation(s)
- Vincenzo Cannizzaro
- Department of Intensive Care and Neonatology, University Children’s Hospital, Zurich, Switzerland
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Zosky GR, Cannizzaro V, Hantos Z, Sly PD. Protective mechanical ventilation does not exacerbate lung function impairment or lung inflammation following influenza A infection. J Appl Physiol (1985) 2009; 107:1472-8. [DOI: 10.1152/japplphysiol.00393.2009] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The degree to which mechanical ventilation induces ventilator-associated lung injury is dependent on the initial acute lung injury (ALI). Viral-induced ALI is poorly studied, and this study aimed to determine whether ALI induced by a clinically relevant infection is exacerbated by protective mechanical ventilation. Adult female BALB/c mice were inoculated with 104.5 plaque-forming units of influenza A/Mem/1/71 in 50 μl of medium or medium alone. This study used a protective ventilation strategy, whereby mice were anesthetized, tracheostomized, and mechanically ventilated for 2 h. Lung mechanics were measured periodically throughout the ventilation period using a modification of the forced oscillation technique to obtain measures of airway resistance and coefficients of tissue damping and tissue elastance. Thoracic gas volume was measured and used to obtain specific airway resistance, tissue damping, and tissue elastance. At the end of the ventilation period, a bronchoalveolar lavage sample was collected to measure inflammatory cells, macrophage inflammatory protein-2, IL-6, TNF-α, and protein leak. Influenza infection caused significant increases in inflammatory cells, protein leak, and deterioration in lung mechanics that were not exacerbated by mechanical ventilation, in contrast to previous studies using bacterial and mouse-specific viral infection. This study highlighted the importance of type and severity of lung injury in determining outcome following mechanical ventilation.
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Affiliation(s)
- Graeme R. Zosky
- Division of Clinical Science, Telethon Institute for Child Health Research, Centre for Child Health Research, University of Western Australia, Subiaco, Western Australia, Australia
| | - Vincenzo Cannizzaro
- Division of Clinical Science, Telethon Institute for Child Health Research, Centre for Child Health Research, University of Western Australia, Subiaco, Western Australia, Australia
| | - Zoltan Hantos
- Division of Clinical Science, Telethon Institute for Child Health Research, Centre for Child Health Research, University of Western Australia, Subiaco, Western Australia, Australia
| | - Peter D. Sly
- Division of Clinical Science, Telethon Institute for Child Health Research, Centre for Child Health Research, University of Western Australia, Subiaco, Western Australia, Australia
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Cannizzaro V, Berry LJ, Nicholls PK, Zosky GR, Turner DJ, Hantos Z, Sly PD. Lung volume recruitment maneuvers and respiratory system mechanics in mechanically ventilated mice. Respir Physiol Neurobiol 2009; 169:243-51. [PMID: 19788941 DOI: 10.1016/j.resp.2009.09.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2009] [Revised: 09/19/2009] [Accepted: 09/23/2009] [Indexed: 11/29/2022]
Abstract
The study aim was to establish how recruitment maneuvers (RMs) influence lung mechanics and to determine whether RMs produce lung injury. Healthy BALB/c mice were allocated to receive positive end-expiratory pressure (PEEP) at 2 or 6 cmH(2)O and volume- (20 or 40 mL/kg) or pressure-controlled (25 cmH(2)O) RMs every 5 or 75 min for 150 min. The low-frequency forced oscillation technique was used to measure respiratory input impedance. Large RMs resulting in peak airway opening pressures (P(ao))>30 cmH(2)O did not increase inflammatory response or affect transcutaneous oxygen saturation but significantly lowered airway resistance, tissue damping and tissue elastance; the latter changes are likely associated with the bimodal pressure-volume behavior observed in mice. PEEP increase alone and application of RMs producing peak P(ao) below 25 cmH(2)O did not prevent or reverse changes in lung mechanics; whereas frequent application of substantial RMs on top of elevated PEEP levels produced stable lung mechanics without signs of lung injury.
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Affiliation(s)
- Vincenzo Cannizzaro
- Division of Clinical Sciences, Telethon Institute for Child Health Research, Centre for Child Health Research, The University of Western Australia, Australia
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Cannizzaro V, Berry LJ, Zosky GR, Turner DJ, Hantos Z, Sly PD. Impact of supplemental oxygen in mechanically ventilated adult and infant mice. Respir Physiol Neurobiol 2008; 165:61-6. [PMID: 18992373 DOI: 10.1016/j.resp.2008.10.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Revised: 10/08/2008] [Accepted: 10/08/2008] [Indexed: 02/06/2023]
Abstract
The aim of the present study was to determine the short-term effects of hyperoxia on respiratory mechanics in mechanically ventilated infant and adult mice. Eight and two week old BALB/c mice were exposed to inspired oxygen fractions [Formula: see text] of 0.21, 0.3, 0.6, and 1.0, respectively, during 120 min of mechanical ventilation. Respiratory system mechanics and inflammatory responses were measured. Using the low-frequency forced oscillation technique no differences were found in airway resistance between different [Formula: see text] groups when corrected for changes in gas viscosity. Coefficients of lung tissue damping and elastance were not different between groups and showed similar changes over time in both age groups. Inflammatory responses did not differ between groups at either age. Hyperoxia had no impact on respiratory mechanics during mechanical ventilation with low tidal volume and positive end-expiratory pressure. Hence, supplemental oxygen can safely be applied during short-term mechanical ventilation strategies in infant and adult mice.
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Affiliation(s)
- Vincenzo Cannizzaro
- Telethon Institute for Child Health Research, Division of Clinical Sciences, Subiaco WA 6008, Australia.
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