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Xu J, Xu X, Li X, He S, Li D, Ji B. Cellular mechanics of wound formation in single cell layer under cyclic stretching. Biophys J 2022; 121:288-299. [PMID: 34902328 PMCID: PMC8790211 DOI: 10.1016/j.bpj.2021.12.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 11/16/2021] [Accepted: 12/09/2021] [Indexed: 01/21/2023] Open
Abstract
Wounds can be produced when cells and tissues are subjected to excessive forces, for instance, under pathological conditions or nonphysiological loading. However, the cellular behaviors in the wound formation process are not clear. Here we tested the behaviors of wound formation in the epithelial layer with an in-suit uniaxial stretching device. We found that the wound often nucleates at the position where the cells are dividing. The polarization direction of cells near the wound is preferentially along the wound edge, whereas the cells far from the wound are preferentially perpendicular to the stretching direction. The larger the wound area is, the higher is the aspect ratio of the cells around the wound. Increasing the cell density will strengthen the cell layer. The higher the cell density is, the smaller is the area of the wounds, and the weaker is the effect of stretching on the polarization of the cells. Furthermore, we built a coarse-grained cell model that can explicitly consider the elasticity and viscoelasticity of cells, cell-cell interaction, and cell active stress, by which we simulated the wound formation process and quantitatively analyzed the force and stress fields in the cell layer, particularly around the wound. These analyses reveal the cellular mechanisms of wound formation behaviors in the cell layer under stretching and shed useful light on tissue engineering and regenerative medicine for biomedical applications.
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Affiliation(s)
- Jiayi Xu
- Department of Applied Mechanics, Beijing Institute of Technology, Beijing, China,Oujiang Laboratory, Zhejiang, Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, China,Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing, China
| | - Xiangyu Xu
- Department of Applied Mechanics, Beijing Institute of Technology, Beijing, China,Oujiang Laboratory, Zhejiang, Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, China
| | - Xiaojun Li
- Department of Applied Mechanics, Beijing Institute of Technology, Beijing, China
| | - Shijie He
- Center for Engineering in Medicine and Surgery, Department of Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Dechang Li
- Department of Engineering Mechanics, Zhejiang University, Hangzhou, China,Corresponding author
| | - Baohua Ji
- Oujiang Laboratory, Zhejiang, Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, China,Department of Engineering Mechanics, Zhejiang University, Hangzhou, China,Corresponding author
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2
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Al-Ruweidi MKAA, Ali FH, Shurbaji S, Popelka A, Yalcin HC. Dexamethasone and transdehydroandrosterone significantly reduce pulmonary epithelial cell injuries associated with mechanical ventilation. J Appl Physiol (1985) 2021; 130:1143-1151. [PMID: 33600286 PMCID: PMC8384562 DOI: 10.1152/japplphysiol.00574.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Many patients who suffer from pulmonary diseases cannot inflate their lungs normally, as they need mechanical ventilation (MV) to assist them. The stress associated with MV can damage the delicate epithelium in small airways and alveoli, which can cause complications resulting in ventilation-induced lung injuries (VILIs) in many cases, especially in patients with acute respiratory distress syndrome (ARDS). Therefore, efforts were directed to develop safe modes for MV. In our work, we propose a different approach to decrease injuries of epithelial cells (EpCs) upon MV. We alter EpCs’ cytoskeletal structure to increase their survival rate during airway reopening conditions associated with MV. We tested two anti-inflammatory drugs dexamethasone (DEX) and transdehydroandrosterone (DHEA) to alter the cytoskeleton. Cultured rat L2 alveolar EpCs were exposed to airway reopening conditions using a parallel-plate perfusion chamber. Cells were exposed to a single bubble propagation to simulate stresses associated with mechanical ventilation in both control and study groups. Cellular injury and cytoskeleton reorganization were assessed via fluorescence microscopy, whereas cell topography was studied via atomic force microscopy (AFM). Our results indicate that culturing cells in media, DEX solution, or DHEA solution did not lead to cell death (static cultures). Bubble flows caused significant cell injury. Preexposure to DEX or DHEA decreased cell death significantly. The AFM verified alteration of cell mechanics due to actin fiber depolymerization. These results suggest potential beneficial effects of DEX and DHEA for ARDS treatment for patients with COVID-19. They are also critical for VILIs and applicable to future clinical studies. NEW & NOTEWORTHY Preexposure of cultured cells to either dexamethasone or transdehydroandrosterone significantly decreases cellular injuries associated with mechanical ventilation due to their ability to alter the cell mechanics. This is an alternative protective method against VILIs instead of common methods that rely on modification of mechanical ventilator modes.
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Affiliation(s)
- Mahmoud Khatib A A Al-Ruweidi
- Biomedical Research Centre, Qatar University, Doha, Qatar.,Department of Chemistry and Earth Sciences, Qatar University, Doha, Qatar
| | | | - Samar Shurbaji
- Biomedical Research Centre, Qatar University, Doha, Qatar
| | - Anton Popelka
- Center of Advanced Materials, Qatar University, Doha, Qatar
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3
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Nagre N, Cong X, Ji HL, Schreiber JM, Fu H, Pepper I, Warren S, Sill JM, Hubmayr RD, Zhao X. Inhaled TRIM72 Protein Protects Ventilation Injury to the Lung through Injury-guided Cell Repair. Am J Respir Cell Mol Biol 2018; 59:635-647. [PMID: 29958015 PMCID: PMC6236686 DOI: 10.1165/rcmb.2017-0364oc] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 06/28/2018] [Indexed: 12/27/2022] Open
Abstract
Studies showed that TRIM72 is essential for repair of alveolar cell membrane disruptions, and exogenous recombinant human TRIM72 protein (rhT72) demonstrated tissue-mending properties in animal models of tissue injury. Here we examine the mechanisms of rhT72-mediated lung cell protection in vitro and test the efficacy of inhaled rhT72 in reducing tissue pathology in a mouse model of ventilator-induced lung injury. In vitro lung cell injury was induced by glass beads and stretching. Ventilator-induced lung injury was modeled by injurious ventilation at 30 ml/kg tidal volume. Affinity-purified rhT72 or control proteins were added into culture medium or applied through nebulization. Cellular uptake and in vivo distribution of rhT72 were detected by imaging and immunostaining. Exogenous rhT72 maintains membrane integrity of alveolar epithelial cells subjected to glass bead injury in a dose-dependent manner. Inhaled rhT72 decreases the number of fatally injured alveolar cells, and ameliorates tissue-damaging indicators and cell injury markers after injurious ventilation. Using in vitro stretching assays, we reveal that rhT72 improves both cellular resilience to membrane wounding and membrane repair after injury. Image analysis detected rhT72 uptake by rat alveolar epithelial cells, which can be inhibited by a cholesterol-disrupting agent. In addition, inhaled rhT72 distributes to the distal lungs, where it colocalizes with phosphatidylserine detection on nonpermeabilized lung slices to label wounded cells. In conclusion, our study showed that inhaled rhT72 accumulates in injured lungs and protects lung tissue from ventilator injury, the mechanisms of which include improving cell resilience to membrane wounding, localizing to injured membrane, and augmenting membrane repair.
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Affiliation(s)
- Nagaraja Nagre
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, Virginia
| | - Xiaofei Cong
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, Virginia
| | - Hong-Long Ji
- Texas Lung Injury Institute, the University of Texas Health Science Center at Tyler, Tyler, Texas
| | - John M. Schreiber
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, Virginia
| | - Hongyun Fu
- Division of Community Health and Research, Pediatrics Department and
| | - Ian Pepper
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, Virginia
| | - Seth Warren
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, Virginia
| | - Joshua M. Sill
- Division of Pulmonary and Critical Care, Department of Internal Medicine, Eastern Virginia Medical School, Norfolk, Virginia; and
| | - Rolf D. Hubmayr
- Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, Minnesota
| | - Xiaoli Zhao
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, Virginia
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4
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Dissipation of energy during the respiratory cycle: conditional importance of ergotrauma to structural lung damage. Curr Opin Crit Care 2018; 24:16-22. [PMID: 29176330 DOI: 10.1097/mcc.0000000000000470] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
PURPOSE OF REVIEW To describe and put into context recent conceptual advances regarding the relationship of energy load and power to ventilator-induced lung injury (VILI). RECENT FINDINGS Investigative emphasis regarding VILI has almost exclusively centered on the static characteristics of the individual tidal cycle - tidal volume, plateau pressure, positive end-expiratory pressure, and driving pressure. Although those static characteristics of the tidal cycle are undeniably important, the 'dynamic' characteristics of ventilation must not be ignored. To inflict the nonrupturing damage we identify as VILI, work must be performed and energy expended by high stress cycles applied at rates that exceed the capacity of endogenous repair. Machine power, the pace at which the work performing energy load is applied by the ventilator, has received increasing scrutiny as a candidate for the proximate and integrative cause of VILI. SUMMARY Although the unmodified values of machine-delivered energy or power (which are based on airway pressures and tidal volumes) cannot serve unconditionally as a rigid and quantitative guide to ventilator adjustment for lung protection, bedside consideration of the dynamics of ventilation and potential for ergotrauma represents a clear conceptual advance that complements the static parameters of the individual tidal cycle that with few exceptions have held our scientific attention.
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5
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Truflandier K, Beaumont E, Maghni K, De Marchie M, Charbonney E, Spahija J. Spinal cord injury modulates the lung inflammatory response in mechanically ventilated rats: a comparative animal study. Physiol Rep 2017; 4:4/24/e13009. [PMID: 28039398 PMCID: PMC5210386 DOI: 10.14814/phy2.13009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 09/25/2016] [Indexed: 12/26/2022] Open
Abstract
Mechanical ventilation (MV) is widely used in spinal injury patients to compensate for respiratory muscle failure. MV is known to induce lung inflammation, while spinal cord injury (SCI) is known to contribute to local inflammatory response. Interaction between MV and SCI was evaluated in order to assess the impact it may have on the pulmonary inflammatory profile. Sprague Dawley rats were anesthetized for 24 h and randomized to receive either MV or not. The MV group included C4-C5 SCI, T10 SCI and uninjured animals. The nonventilated (NV) group included T10 SCI and uninjured animals. Inflammatory cytokine profile, inflammation related to the SCI level, and oxidative stress mediators were measured in the bronchoalveolar lavage (BAL). The cytokine profile in BAL of MV animals showed increased levels of TNF-α, IL-1β, IL-6 and a decrease in IL-10 (P = 0.007) compared to the NV group. SCI did not modify IL-6 and IL-10 levels either in the MV or the NV groups, but cervical injury induced a decrease in IL-1β levels in MV animals. Cervical injury also reduced MV-induced pulmonary oxidative stress responses by decreasing isoprostane levels while increasing heme oxygenase-1 level. The thoracic SCI in NV animals increased M-CSF expression and promoted antioxidant pulmonary responses with low isoprostane and high heme oxygenase-1 levels. SCI shows a positive impact on MV-induced pulmonary inflammation, modulating specific lung immune and oxidative stress responses. Inflammation induced by MV and SCI interact closely and may have strong clinical implications since effective treatment of ventilated SCI patients may amplify pulmonary biotrauma.
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Affiliation(s)
- Karine Truflandier
- Research Center, Sacré-Cœur Hospital of Montreal, Department of Medicine, Université de Montréal, Montreal, Quebec, Canada
| | - Eric Beaumont
- Research Center, Sacré-Cœur Hospital of Montreal, Department of Medicine, Université de Montréal, Montreal, Quebec, Canada.,Department of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee
| | - Karim Maghni
- Research Center, Sacré-Cœur Hospital of Montreal, Department of Medicine, Université de Montréal, Montreal, Quebec, Canada
| | - Michel De Marchie
- Department of Adult Critical Care, Jewish General Hospital McGill University, Montréal, Quebec, Canada
| | - Emmanuel Charbonney
- Research Center, Sacré-Cœur Hospital of Montreal, Department of Medicine, Université de Montréal, Montreal, Quebec, Canada
| | - Jadranka Spahija
- Research Center, Sacré-Cœur Hospital of Montreal, Department of Medicine, Université de Montréal, Montreal, Quebec, Canada .,School of Physical and Occupational Therapy, McGill University, Montreal, Quebec, Canada.,Center for Interdisciplinary Research in Rehabilitation in Montreal, Jewish Rehabilitation Hospital, Laval, Quebec, Canada
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6
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Kuhn H, Nieuwenhuijsen H, Karthe B, Wirtz H. Stretch-induced apoptosis in rat alveolar epithelial cells is mediated by the intrinsic mitochondrial pathway. Exp Lung Res 2017; 43:49-56. [DOI: 10.1080/01902148.2017.1287228] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Hartmut Kuhn
- Department of Respiratory Medicine, University of Leipzig, Leipzig, Germany
| | | | - Bianca Karthe
- Department of Respiratory Medicine, University of Leipzig, Leipzig, Germany
| | - Hubert Wirtz
- Department of Respiratory Medicine, University of Leipzig, Leipzig, Germany
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7
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Cong X, Hubmayr RD, Li C, Zhao X. Plasma membrane wounding and repair in pulmonary diseases. Am J Physiol Lung Cell Mol Physiol 2017; 312:L371-L391. [PMID: 28062486 PMCID: PMC5374305 DOI: 10.1152/ajplung.00486.2016] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 01/05/2017] [Accepted: 01/05/2017] [Indexed: 12/12/2022] Open
Abstract
Various pathophysiological conditions such as surfactant dysfunction, mechanical ventilation, inflammation, pathogen products, environmental exposures, and gastric acid aspiration stress lung cells, and the compromise of plasma membranes occurs as a result. The mechanisms necessary for cells to repair plasma membrane defects have been extensively investigated in the last two decades, and some of these key repair mechanisms are also shown to occur following lung cell injury. Because it was theorized that lung wounding and repair are involved in the pathogenesis of acute respiratory distress syndrome (ARDS) and idiopathic pulmonary fibrosis (IPF), in this review, we summarized the experimental evidence of lung cell injury in these two devastating syndromes and discuss relevant genetic, physical, and biological injury mechanisms, as well as mechanisms used by lung cells for cell survival and membrane repair. Finally, we discuss relevant signaling pathways that may be activated by chronic or repeated lung cell injury as an extension of our cell injury and repair focus in this review. We hope that a holistic view of injurious stimuli relevant for ARDS and IPF could lead to updated experimental models. In addition, parallel discussion of membrane repair mechanisms in lung cells and injury-activated signaling pathways would encourage research to bridge gaps in current knowledge. Indeed, deep understanding of lung cell wounding and repair, and discovery of relevant repair moieties for lung cells, should inspire the development of new therapies that are likely preventive and broadly effective for targeting injurious pulmonary diseases.
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Affiliation(s)
- Xiaofei Cong
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, Virginia
| | - Rolf D Hubmayr
- Emerius, Thoracic Diseases Research Unit, Mayo Clinic, Rochester, Minnesota; and
| | - Changgong Li
- Department of Pediatrics, University of Southern California, Los Angeles, California
| | - Xiaoli Zhao
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, Virginia;
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8
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Arroyo M, Trepat X. Hydraulic fracturing in cells and tissues: fracking meets cell biology. Curr Opin Cell Biol 2016; 44:1-6. [PMID: 27936415 DOI: 10.1016/j.ceb.2016.11.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 11/10/2016] [Indexed: 01/23/2023]
Abstract
The animal body is largely made of water. A small fraction of body water is freely flowing in blood and lymph, but most of it is trapped in hydrogels such as the extracellular matrix (ECM), the cytoskeleton, and chromatin. Besides providing a medium for biological molecules to diffuse, water trapped in hydrogels plays a fundamental mechanical role. This role is well captured by the theory of poroelasticity, which explains how any deformation applied to a hydrogel causes pressure gradients and water flows, much like compressing a sponge squeezes water out of it. Here we review recent evidence that poroelastic pressures and flows can fracture essential biological barriers such as the nuclear envelope, the cellular cortex, and epithelial layers. This type of fracture is known in engineering literature as hydraulic fracturing or 'fracking'.
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Affiliation(s)
- Marino Arroyo
- Universitat Politècnica de Catalunya-BarcelonaTech, Spain.
| | - Xavier Trepat
- Institute for Bioengineering of Catalonia, Barcelona, Spain; Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain; Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina, 28029 Madrid, Spain.
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9
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Abstract
Abstract
Background
The ventilator works mechanically on the lung parenchyma. The authors set out to obtain the proof of concept that ventilator-induced lung injury (VILI) depends on the mechanical power applied to the lung.
Methods
Mechanical power was defined as the function of transpulmonary pressure, tidal volume (TV), and respiratory rate. Three piglets were ventilated with a mechanical power known to be lethal (TV, 38 ml/kg; plateau pressure, 27 cm H2O; and respiratory rate, 15 breaths/min). Other groups (three piglets each) were ventilated with the same TV per kilogram and transpulmonary pressure but at the respiratory rates of 12, 9, 6, and 3 breaths/min. The authors identified a mechanical power threshold for VILI and did nine additional experiments at the respiratory rate of 35 breaths/min and mechanical power below (TV 11 ml/kg) and above (TV 22 ml/kg) the threshold.
Results
In the 15 experiments to detect the threshold for VILI, up to a mechanical power of approximately 12 J/min (respiratory rate, 9 breaths/min), the computed tomography scans showed mostly isolated densities, whereas at the mechanical power above approximately 12 J/min, all piglets developed whole-lung edema. In the nine confirmatory experiments, the five piglets ventilated above the power threshold developed VILI, but the four piglets ventilated below did not. By grouping all 24 piglets, the authors found a significant relationship between the mechanical power applied to the lung and the increase in lung weight (r2 = 0.41, P = 0.001) and lung elastance (r2 = 0.33, P < 0.01) and decrease in Pao2/Fio2 (r2 = 0.40, P < 0.001) at the end of the study.
Conclusion
In piglets, VILI develops if a mechanical power threshold is exceeded.
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10
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Chen H, Liang ZW, Wang ZH, Zhang JP, Hu B, Xing XB, Cai WB. Akt Activation and Inhibition of Cytochrome C Release: Mechanistic Insights into Leptin-promoted Survival of Type II Alveolar Epithelial Cells. J Cell Biochem 2015; 116:2313-24. [PMID: 25833759 DOI: 10.1002/jcb.25182] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 03/31/2015] [Indexed: 11/09/2022]
Affiliation(s)
- Hui Chen
- Department of Obstetrics and Gynecology; Sun Yat-sen Memorial Hospital; Guangdong Province China
- Key Laboratory of malignant tumor gene regulation and target therapy of Guangdong Higher Education Institutes; Sun Yat-sen Memorial Hospital; Guangdong Province China
| | - Zhen-Wei Liang
- Department of Biochemistry; Zhongshan School of Medicine; Sun Yat-sen University; Guangdong Province China
- Center for Disease Model Animals; Sun Yat-sen University; Guangdong Province China
| | - Zhen-Hua Wang
- Department of Obstetrics and Gynecology; Sun Yat-sen Memorial Hospital; Guangdong Province China
| | - Jian-Ping Zhang
- Department of Obstetrics and Gynecology; Sun Yat-sen Memorial Hospital; Guangdong Province China
| | - Bo Hu
- Department of Laboratory Medicine; The Third Affiliated Hospital of Sun Yat-sen University; Guangdong Province China
| | - Xiang-Bin Xing
- Department of Gastroenterology; The First Affiliated Hospital of Sun Yat-sen University; Guangdong Province China
| | - Wei-Bin Cai
- Department of Biochemistry; Zhongshan School of Medicine; Sun Yat-sen University; Guangdong Province China
- Center for Disease Model Animals; Sun Yat-sen University; Guangdong Province China
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11
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Casares L, Vincent R, Zalvidea D, Campillo N, Navajas D, Arroyo M, Trepat X. Hydraulic fracture during epithelial stretching. NATURE MATERIALS 2015; 14:343-51. [PMID: 25664452 PMCID: PMC4374166 DOI: 10.1038/nmat4206] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 12/23/2014] [Indexed: 05/07/2023]
Abstract
The origin of fracture in epithelial cell sheets subject to stretch is commonly attributed to excess tension in the cells' cytoskeleton, in the plasma membrane, or in cell-cell contacts. Here, we demonstrate that for a variety of synthetic and physiological hydrogel substrates the formation of epithelial cracks is caused by tissue stretching independently of epithelial tension. We show that the origin of the cracks is hydraulic; they result from a transient pressure build-up in the substrate during stretch and compression manoeuvres. After pressure equilibration, cracks heal readily through actomyosin-dependent mechanisms. The observed phenomenology is captured by the theory of poroelasticity, which predicts the size and healing dynamics of epithelial cracks as a function of the stiffness, geometry and composition of the hydrogel substrate. Our findings demonstrate that epithelial integrity is determined in a tension-independent manner by the coupling between tissue stretching and matrix hydraulics.
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Affiliation(s)
- Laura Casares
- Institute for Bioengineering of Catalonia, Barcelona, Spain
| | | | | | - Noelia Campillo
- Institute for Bioengineering of Catalonia, Barcelona, Spain
- Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona, and CIBERES, Spain
| | - Daniel Navajas
- Institute for Bioengineering of Catalonia, Barcelona, Spain
- Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona, and CIBERES, Spain
| | - Marino Arroyo
- Universitat Politècnica de Catalunya-BarcelonaTech, Spain
- Corresponding authors: Marino Arroyo, Universitat Politècnica de Catalunya, Carrer Jordi Girona 1, 08034, Barcelona, Spain, (+34) 934 011 805, ; Xavier Trepat, Institute for Bioengineering of Catalonia, Ed. Hèlix, Baldiri i Reixac, 15-21, 08028, Barcelona, Spain, (+34) 934 020 265,
| | - Xavier Trepat
- Institute for Bioengineering of Catalonia, Barcelona, Spain
- Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona, and CIBERES, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
- Corresponding authors: Marino Arroyo, Universitat Politècnica de Catalunya, Carrer Jordi Girona 1, 08034, Barcelona, Spain, (+34) 934 011 805, ; Xavier Trepat, Institute for Bioengineering of Catalonia, Ed. Hèlix, Baldiri i Reixac, 15-21, 08028, Barcelona, Spain, (+34) 934 020 265,
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12
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Kim SC, Kellett T, Wang S, Nishi M, Nagre N, Zhou B, Flodby P, Shilo K, Ghadiali SN, Takeshima H, Hubmayr RD, Zhao X. TRIM72 is required for effective repair of alveolar epithelial cell wounding. Am J Physiol Lung Cell Mol Physiol 2014; 307:L449-59. [PMID: 25106429 DOI: 10.1152/ajplung.00172.2014] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The molecular mechanisms for lung cell repair are largely unknown. Previous studies identified tripartite motif protein 72 (TRIM72) from striated muscle and linked its function to tissue repair. In this study, we characterized TRIM72 expression in lung tissues and investigated the role of TRIM72 in repair of alveolar epithelial cells. In vivo injury of lung cells was introduced by high tidal volume ventilation, and repair-defective cells were labeled with postinjury administration of propidium iodide. Primary alveolar epithelial cells were isolated and membrane wounding and repair were labeled separately. Our results show that absence of TRIM72 increases susceptibility to deformation-induced lung injury whereas TRIM72 overexpression is protective. In vitro cell wounding assay revealed that TRIM72 protects alveolar epithelial cells through promoting repair rather than increasing resistance to injury. The repair function of TRIM72 in lung cells is further linked to caveolin 1. These data suggest an essential role for TRIM72 in repair of alveolar epithelial cells under plasma membrane stress failure.
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Affiliation(s)
- Seong Chul Kim
- Division of Pharmacology, College of Pharmacy, The Ohio State University, Columbus, Ohio
| | - Thomas Kellett
- Division of Pharmacology, College of Pharmacy, The Ohio State University, Columbus, Ohio
| | - Shaohua Wang
- Thoracic Diseases Research Unit, Mayo Clinic, Rochester, Minnesota
| | - Miyuki Nishi
- Department of Biological Chemistry, Kyoto University Graduate School of Pharmaceutical Sciences, Kyoto, Japan
| | - Nagaraja Nagre
- Division of Pharmacology, College of Pharmacy, The Ohio State University, Columbus, Ohio
| | - Beiyun Zhou
- Will Rogers Institute Pulmonary Research Center, Division of Pulmonary, Critical Care and Sleep Medicine, University of Southern California, Los Angeles, California
| | - Per Flodby
- Will Rogers Institute Pulmonary Research Center, Division of Pulmonary, Critical Care and Sleep Medicine, University of Southern California, Los Angeles, California
| | - Konstantin Shilo
- Thoracic Pathology Division, Department of Pathology, The Ohio State University, Columbus, Ohio
| | - Samir N Ghadiali
- Biomedical Engineering Department, College of Engineering, The Ohio State University, Columbus, Ohio; and
| | - Hiroshi Takeshima
- Department of Biological Chemistry, Kyoto University Graduate School of Pharmaceutical Sciences, Kyoto, Japan
| | - Rolf D Hubmayr
- Thoracic Diseases Research Unit, Mayo Clinic, Rochester, Minnesota
| | - Xiaoli Zhao
- Division of Pharmacology, College of Pharmacy, The Ohio State University, Columbus, Ohio; Division of Pulmonary, Critical Care, Allergy and Sleep Medicine, College of Medicine, The Ohio State University, Columbus, Ohio
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13
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Ravikumar P, Yilmaz C, Dane DM, Bellotto DJ, Estrera AS, Hsia CCW. Defining a stimuli-response relationship in compensatory lung growth following major resection. J Appl Physiol (1985) 2014; 116:816-24. [PMID: 24481960 DOI: 10.1152/japplphysiol.01291.2013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Major lung resection is a robust model that mimics the consequences of loss-of-functioning lung units. We previously observed in adult canines, following 42% and 58% lung resection, a critical threshold of stimuli intensity for the initiation of compensatory lung growth. To define the range and limits of this stimuli-response relationship, we performed morphometric analysis on the remaining lobes of adult dogs, 2-3 years after surgical removal of ∼ 70% of lung units in the presence or absence of mediastinal shift. Results were expressed as ratios to that in corresponding control lobes. Lobar expansion and extravascular tissue growth (∼ 3.8- and ∼ 2.0-fold of normal, respectively) were heterogeneous; the lobes remaining next to the diaphragm exhibited a greater response. Tissue growth and capillary formation, indexed by double-capillary profiles, increased, regardless of mediastinal shift. Septal collagen fibers increased up to 2.7-fold, suggesting a greater need for structural support. Compared with previous cohorts following less-extensive resection, tissue volume and gas-exchange surface areas increased significantly only in the infracardiac lobe following 42% resection, exceeded two- to threefold in all lobes following 58% resection, and then exhibited diminished gains following ∼ 70% resection. In contrast, alveolar-capillary formation increased with incremental resection without reaching an upper limit. Overall structural regrowth was most vigorous and uniform following 58% resection. The diminishment of gains in tissue growth, following ∼ 70% resection, could reflect excessive or maldistributed mechanical stress that threatens septal integrity. Results also suggest additional independent stimuli of alveolar-capillary formation, possibly related to the postresection augmentation of regional perfusion.
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Affiliation(s)
- Priya Ravikumar
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
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Herold S, Gabrielli NM, Vadász I. Novel concepts of acute lung injury and alveolar-capillary barrier dysfunction. Am J Physiol Lung Cell Mol Physiol 2013; 305:L665-81. [PMID: 24039257 DOI: 10.1152/ajplung.00232.2013] [Citation(s) in RCA: 137] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
In this review we summarize recent major advances in our understanding on the molecular mechanisms, mediators, and biomarkers of acute lung injury (ALI) and alveolar-capillary barrier dysfunction, highlighting the role of immune cells, inflammatory and noninflammatory signaling events, mechanical noxae, and the affected cellular and molecular entities and functions. Furthermore, we address novel aspects of resolution and repair of ALI, as well as putative candidates for treatment of ALI, including pharmacological and cellular therapeutic means.
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Affiliation(s)
- Susanne Herold
- Dept. of Internal Medicine, Justus Liebig Univ., Universities of Giessen and Marburg Lung Center, Klinikstrasse 33, 35392 Giessen, Germany.
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15
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Mechanisms of acute respiratory distress syndrome in children and adults: a review and suggestions for future research. Pediatr Crit Care Med 2013; 14:631-43. [PMID: 23823199 DOI: 10.1097/pcc.0b013e318291753f] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
OBJECTIVES To provide a current overview of the epidemiology and pathophysiology of acute respiratory distress syndrome in adults and children, and to identify research questions that will address the differences between adults and children with acute respiratory distress syndrome. DATA SOURCES Narrative literature review and author-generated data. DATA SELECTION The epidemiology of acute respiratory distress syndrome in adults and children, lung morphogenesis, and postnatal lung growth and development are reviewed. The pathophysiology of acute respiratory distress syndrome is divided into eight categories: alveolar fluid transport, surfactant, innate immunity, apoptosis, coagulation, direct alveolar epithelial injury by bacterial products, ventilator-associated lung injury, and repair. DATA EXTRACTION AND SYNTHESIS Epidemiologic data suggest significant differences in the prevalence and mortality of acute respiratory distress syndrome between children and adults. Postnatal lung development continues through attainment of adult height, and there is overlap between the regulation of postnatal lung development and inflammatory, apoptotic, alveolar fluid clearance, and repair mechanisms. Therefore, there is a different biological baseline network of gene and protein expression in children as compared with adults. CONCLUSIONS There are significant obstacles to performing research on children with acute respiratory distress syndrome. However, epidemiologic, clinical, and animal studies suggest age-dependent differences in the pathophysiology of acute respiratory distress syndrome. In order to reduce the prevalence and improve the outcome of patients with acute respiratory distress syndrome, translational studies of inflammatory, apoptotic, alveolar fluid clearance, and repair mechanisms are needed. Understanding the differences in pathophysiologic mechanisms in acute respiratory distress syndrome between children and adults should facilitate identification of novel therapeutic interventions to prevent or modulate lung injury and improve lung repair.
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Hobi N, Ravasio A, Haller T. Interfacial stress affects rat alveolar type II cell signaling and gene expression. Am J Physiol Lung Cell Mol Physiol 2012; 303:L117-29. [PMID: 22610352 DOI: 10.1152/ajplung.00340.2011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Previous work from our group (Ravasio A, Hobi N, Bertocchi C, Jesacher A, Dietl P, Haller T. Am J Physiol Cell Physiol 300: C1456-C1465, 2011.) showed that contact of alveolar epithelial type II cells with an air-liquid interface (I(AL)) leads to a paradoxical situation. It is a potential threat that can cause cell injury, but also a Ca(2+)-dependent stimulus for surfactant secretion. Both events can be explained by the impact of interfacial tensile forces on cellular structures. Here, the strength of this mechanical stimulus became also apparent in microarray studies by a rapid and significant change on the transcriptional level. Cells challenged with an I(AL) in two different ways showed activation/inactivation of cellular pathways involved in stress response and defense, and a detailed Pubmatrix search identified genes associated with several lung diseases and injuries. Altogether, they suggest a close relationship of interfacial stress sensation with current models in alveolar micromechanics. Further similarities between I(AL) and cell stretch were found with respect to the underlying signaling events. The source of Ca(2+) was extracellular, and the transmembrane Ca(2+) entry pathway suggests the involvement of a mechanosensitive channel. We conclude that alveolar type II cells, due to their location and morphology, are specific sensors of the I(AL), but largely protected from interfacial stress by surfactant release.
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Affiliation(s)
- Nina Hobi
- Department of Physiology and Medical Physics, Division of Physiology, Innsbruck Medical University, Austria
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Dietl P, Haller T, Frick M. Spatio-temporal aspects, pathways and actions of Ca(2+) in surfactant secreting pulmonary alveolar type II pneumocytes. Cell Calcium 2012; 52:296-302. [PMID: 22591642 DOI: 10.1016/j.ceca.2012.04.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 04/11/2012] [Accepted: 04/18/2012] [Indexed: 01/16/2023]
Abstract
The type II cell of the pulmonary alveolus is a polarized epithelial cell that secretes surfactant into the alveolar space by regulated exocytosis of lamellar bodies (LBs). This process consists of multiple sequential steps and is correlated to elevations of the cytoplasmic Ca(2+) concentration ([Ca(2+)](c)) required for extended periods of secretory activity. Both chemical (purinergic) and mechanical (cell stretch or exposure to an air-liquid interface) stimuli give rise to complex Ca(2+) signals (such as Ca(2+) peaks, spikes and plateaus) that differ in shape, origin and spatio-temporal behavior. This review summarizes current knowledge about Ca(2+) channels, including vesicular P2X4 purinoceptors, in type II cells and associated signaling cascades within the alveolar microenvironment, and relates stimulus-dependent activation of these pathways with distinct stages of surfactant secretion, including pre- and postfusion stages of LB exocytosis.
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Affiliation(s)
- Paul Dietl
- Institute of General Physiology, University of Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
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18
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Akopova I, Tatur S, Grygorczyk M, Luchowski R, Gryczynski I, Gryczynski Z, Borejdo J, Grygorczyk R. Imaging exocytosis of ATP-containing vesicles with TIRF microscopy in lung epithelial A549 cells. Purinergic Signal 2012; 8:59-70. [PMID: 21881960 PMCID: PMC3286538 DOI: 10.1007/s11302-011-9259-2] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Accepted: 08/16/2011] [Indexed: 12/11/2022] Open
Abstract
Nucleotide release constitutes the first step of the purinergic signaling cascade, but its underlying mechanisms remain incompletely understood. In alveolar A549 cells much of the experimental data is consistent with Ca(2+)-regulated vesicular exocytosis, but definitive evidence for such a release mechanism is missing, and alternative pathways have been proposed. In this study, we examined ATP secretion from A549 cells by total internal reflection fluorescence microscopy to directly visualize ATP-loaded vesicles and their fusion with the plasma membrane. A549 cells were labeled with quinacrine or Bodipy-ATP, fluorescent markers of intracellular ATP storage sites, and time-lapse imaging of vesicles present in the evanescent field was undertaken. Under basal conditions, individual vesicles showed occasional quasi-instantaneous loss of fluorescence, as expected from spontaneous vesicle fusion with the plasma membrane and dispersal of its fluorescent cargo. Hypo-osmotic stress stimulation (osmolality reduction from 316 to 160 mOsm) resulted in a transient, several-fold increment of exocytotic event frequency. Lowering the temperature from 37°C to 20°C dramatically diminished the fraction of vesicles that underwent exocytosis during the 2-min stimulation, from ~40% to ≤1%, respectively. Parallel ATP efflux experiments with luciferase bioluminescence assay revealed that pharmacological interference with vesicular transport (brefeldin, monensin), or disruption of the cytoskeleton (nocodazole, cytochalasin), significantly suppressed ATP release (by up to ~80%), whereas it was completely blocked by N-ethylmaleimide. Collectively, our data demonstrate that regulated exocytosis of ATP-loaded vesicles likely constitutes a major pathway of hypotonic stress-induced ATP secretion from A549 cells.
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Affiliation(s)
- Irina Akopova
- Center for Commercialization of Fluorescence Technologies, Department of Molecular Biology and Immunology, University of North Texas, Fort Worth, TX USA
| | - Sabina Tatur
- Research Centre, Centre hospitalier de l’Université de Montréal (CRCHUM)—Hôtel-Dieu, 3850 St. Urbain St., Montreal, QC Canada H2W 1T7
| | - Mariusz Grygorczyk
- Research Centre, Centre hospitalier de l’Université de Montréal (CRCHUM)—Hôtel-Dieu, 3850 St. Urbain St., Montreal, QC Canada H2W 1T7
| | - Rafał Luchowski
- Center for Commercialization of Fluorescence Technologies, Department of Molecular Biology and Immunology, University of North Texas, Fort Worth, TX USA
| | - Ignacy Gryczynski
- Center for Commercialization of Fluorescence Technologies, Department of Molecular Biology and Immunology, University of North Texas, Fort Worth, TX USA
- Department of Cell Biology and Anatomy, University of North Texas, Fort Worth, TX USA
| | - Zygmunt Gryczynski
- Center for Commercialization of Fluorescence Technologies, Department of Molecular Biology and Immunology, University of North Texas, Fort Worth, TX USA
- Department of Physics and Astronomy, Texas Christian University, Fort Worth, TX USA
| | - Julian Borejdo
- Center for Commercialization of Fluorescence Technologies, Department of Molecular Biology and Immunology, University of North Texas, Fort Worth, TX USA
| | - Ryszard Grygorczyk
- Research Centre, Centre hospitalier de l’Université de Montréal (CRCHUM)—Hôtel-Dieu, 3850 St. Urbain St., Montreal, QC Canada H2W 1T7
- Department of Medicine, Université de Montréal, Montreal, Quebec Canada
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Plataki M, Lee YD, Rasmussen DL, Hubmayr RD. Poloxamer 188 facilitates the repair of alveolus resident cells in ventilator-injured lungs. Am J Respir Crit Care Med 2011; 184:939-47. [PMID: 21778295 DOI: 10.1164/rccm.201104-0647oc] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
RATIONALE Wounded alveolus resident cells are identified in human and experimental acute respiratory distress syndrome models. Poloxamer 188 (P188) is an amphiphilic macromolecule shown to have plasma membrane-sealing properties in various cell types. OBJECTIVES To investigate whether P188 (1) protects alveolus resident cells from necrosis and (2) is associated with reduced ventilator-induced lung injury in live rats, isolated perfused rat lungs, and scratch and stretch-wounded alveolar epithelial cells. METHODS Seventy-four live rats and 18 isolated perfused rat lungs were ventilated with injurious or protective strategies while infused with P188 or control solution. Alveolar epithelial cell monolayers were subjected to scratch or stretch wounding in the presence or absence of P188. MEASUREMENTS AND MAIN RESULTS P188 was associated with fewer mortally wounded alveolar cells in live rats and isolated perfused lungs. In vitro, P188 reduced the number of injured and necrotic cells, suggesting that P188 promotes cell repair and renders plasma membranes more resilient to deforming stress. The enhanced cell survival was accompanied by improvement in conventional measures of lung injury (peak airway pressure, wet-to-dry weight ratio) only in the ex vivo-perfused lung preparation and not in the live animal model. CONCLUSIONS P188 facilitates plasma membrane repair in alveolus resident cells, but has no salutary effects on lung mechanics or vascular barrier properties in live animals. This discordance may have pathophysiological significance for the interdependence of different injury mechanisms and therapeutic implications regarding the benefits of prolonging the life of stress-activated cells.
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Affiliation(s)
- Maria Plataki
- Thoracic Diseases Research Unit, Division of Pulmonary and Critical Care Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
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20
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Hoegl S, Bachmann M, Scheiermann P, Goren I, Hofstetter C, Pfeilschifter J, Zwissler B, Muhl H. Protective properties of inhaled IL-22 in a model of ventilator-induced lung injury. Am J Respir Cell Mol Biol 2011; 44:369-76. [PMID: 20463292 DOI: 10.1165/rcmb.2009-0440oc] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
High-pressure ventilation induces barotrauma and pulmonary inflammation, thus leading to ventilator-induced lung injury (VILI). IL-22 has both immunoregulatory and tissue-protective properties. Functional IL-22 receptor expression is restricted to nonleukocytic cells, such as alveolar epithelial cells. When applied via inhalation, IL-22 reaches the pulmonary system directly and in high concentrations, and may protect alveolar epithelial cells against cellular stress and biotrauma associated with VILI. In A549 lung epithelial cells, IL-22 was able to induce rapid signal transducer and activator of transcription (STAT)-3 phosphorylation/activation, and hereon mediated stable suppressor of cytokine signaling (SOCS) 3 expression detectable even 24 hours after onset of stimulation. In a rat model of VILI, the prophylactic inhalation of IL-22 before induction of VILI (peak airway pressure = 45 cm H(2)O) protected the lung against pulmonary disintegration and edema. IL-22 reduced VILI-associated biotrauma (i.e., pulmonary concentrations of macrophage inflammatory protein-2, IL-6, and matrix metalloproteinase 9) and mediated pulmonary STAT3/SOCS3 activation. In addition, despite a short observation period of 4 hours, inhaled IL-22 resulted in an improved survival of the rats. These data support the hypothesis that IL-22, likely via activation of STAT3 and downstream genes (e.g., SOCS3), is able to protect against cell stretch and pulmonary baro-/biotrauma by enhancing epithelial cell resistibility.
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Affiliation(s)
- Sandra Hoegl
- Clinic for Anesthesiology, University Hospital of Ludwig-Maximilians-University, Munich, Germany.
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21
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Ravasio A, Hobi N, Bertocchi C, Jesacher A, Dietl P, Haller T. Interfacial sensing by alveolar type II cells: a new concept in lung physiology? Am J Physiol Cell Physiol 2011; 300:C1456-65. [PMID: 21270294 DOI: 10.1152/ajpcell.00427.2010] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Alveolar type II (AT II) cells are in close contact with an air-liquid interface (I(AL)). This contact may be of considerable physiological relevance; however, no data exist to provide a satisfying description of this specific microenvironment. This is mainly due to the experimental difficulty to manipulate and analyze cell-air contacts in a specific way. Therefore, we designed assays to quantify cell viability, Ca(2+) changes, and exocytosis in the course of interface contact and miniaturized I(AL) devices for direct, subcellular, and real-time analyses of cell-interface interactions by fluorescence microscopy or interferometry. The studies demonstrated that the sole presence of an I(AL) is not sensed by the cells. However, when AT II cells are forced into closer contact with it, they respond promptly with sustained Ca(2+) signals and surfactant exocytosis before the occurrence of irreversible cell damage. This points to a paradoxical situation: a potential threat and potent stimulus for the cells. Furthermore, we found that the signalling mechanism underlying sensation of an I(AL) can be sufficiently explained by mechanical forces. These results demonstrate that the I(AL) itself can play a major, although so-far neglected, role in lung physiology, particularly in the regulatory mechanisms related with surfactant homeostasis. Moreover, they also support a general new concept of mechanosensation in the lung.
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Affiliation(s)
- Andrea Ravasio
- Dept. of Physiology and Medical Physics, Division of Physiology, Innsbruck Medical University, Fritz-Pregl-Strasse 3, Innsbruck, Austria
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22
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Letsiou E, Kitsiouli E, Nakos G, Lekka ME. Mild stretch activates cPLA2 in alveolar type II epithelial cells independently through the MEK/ERK and PI3K pathways. Biochim Biophys Acta Mol Cell Biol Lipids 2010; 1811:370-6. [PMID: 21185392 DOI: 10.1016/j.bbalip.2010.12.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Revised: 12/15/2010] [Accepted: 12/16/2010] [Indexed: 10/18/2022]
Abstract
Alveolar epithelial type II cells (AT II) in which lung surfactant synthesis and secretion take place, are subjected to low magnitude stretch during normal breathing. The aim of the study was to explore the effect of mild stretch on phospholipase A(2) (PLA(2)) activation, an enzyme known to be involved in surfactant secretion. In A549 cells (a model of AT II cells), we showed, using a fluorometric assay, that stretch triggers an increase of total PLA(2) activity. Western blot experiments revealed that the cytosolic isoform cPLA(2) is rapidly phosphorylated under stretch, in addition to a modest increase in cPLA(2) mRNA levels. Treatment of A549 cells with selective inhibitors of the MEK/ERK pathway significantly attenuated the stretch-induced cPLA(2) phosphorylation. A strong interaction of cPLA(2) and pERK enzymes was demonstrated by immunoprecipitation. We also found that inhibition of PI3K pathway attenuated cPLA(2) activation after stretch, without affecting pERK levels. Our results suggest that low magnitude stretch can induce cPLA(2) phosphorylation through the MEK/ERK and PI3K-Akt pathways, independently.
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Affiliation(s)
- Eleftheria Letsiou
- Biochemistry Laboratory, Chemistry Department, University of Ioannina, 45110, Ioannina, Greece
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23
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Plataki M, Hubmayr RD. The physical basis of ventilator-induced lung injury. Expert Rev Respir Med 2010. [PMID: 20524920 DOI: 10.1586/ers.10.28.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Although mechanical ventilation (MV) is a life-saving intervention for patients with acute respiratory distress syndrome (ARDS), it can aggravate or cause lung injury, known as ventilator-induced lung injury (VILI). The biophysical characteristics of heterogeneously injured ARDS lungs increase the parenchymal stress associated with breathing, which is further aggravated by MV. Cells, in particular those lining the capillaries, airways and alveoli, transform this strain into chemical signals (mechanotransduction). The interaction of reparative and injurious mechanotransductive pathways leads to VILI. Several attempts have been made to identify clinical surrogate measures of lung stress/strain (e.g., density changes in chest computed tomography, lower and upper inflection points of the pressure-volume curve, plateau pressure and inflammatory cytokine levels) that could be used to titrate MV. However, uncertainty about the topographical distribution of stress relative to that of the susceptibility of the cells and tissues to injury makes the existence of a single 'global' stress/strain injury threshold doubtful.
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Affiliation(s)
- Maria Plataki
- Thoracic Disease Research Unit, Division of Pulmonary and Critical Care Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
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24
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New insights into experimental evidence on atelectasis and causes of lung injury. Best Pract Res Clin Anaesthesiol 2010; 24:171-82. [DOI: 10.1016/j.bpa.2010.02.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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25
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Abstract
Although mechanical ventilation (MV) is a life-saving intervention for patients with acute respiratory distress syndrome (ARDS), it can aggravate or cause lung injury, known as ventilator-induced lung injury (VILI). The biophysical characteristics of heterogeneously injured ARDS lungs increase the parenchymal stress associated with breathing, which is further aggravated by MV. Cells, in particular those lining the capillaries, airways and alveoli, transform this strain into chemical signals (mechanotransduction). The interaction of reparative and injurious mechanotransductive pathways leads to VILI. Several attempts have been made to identify clinical surrogate measures of lung stress/strain (e.g., density changes in chest computed tomography, lower and upper inflection points of the pressure-volume curve, plateau pressure and inflammatory cytokine levels) that could be used to titrate MV. However, uncertainty about the topographical distribution of stress relative to that of the susceptibility of the cells and tissues to injury makes the existence of a single 'global' stress/strain injury threshold doubtful.
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Affiliation(s)
- Maria Plataki
- Thoracic Disease Research Unit, Division of Pulmonary and Critical Care Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - Rolf D Hubmayr
- Thoracic Disease Research Unit, Division of Pulmonary and Critical Care Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
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26
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Pathways for the influx of molecules into cercariae of Schistosoma mansoni during skin penetration. Parasitology 2010; 137:1089-98. [DOI: 10.1017/s0031182009991983] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
SUMMARYIt has been observed that fluorescent membrane-impermeant molecules can enter the cercariae as they penetrate mouse skin. The hypothesis to be tested was that such molecules, which included Lucifer Yellow and a variety of fluorescent dextrans, entered the parasite through the nephridiopore and excretory tubules as well as through the surface membrane. FITC-labelled poly-L-lysine (molecular weight 10 kDa), added at 4°C during syringe transformation, was found to enter the nephridiopore and labelled the excretory bladder and sometimes the excretory tubules. This finding indicates that macromolecules (10 kDa) can enter the nephridiopore. It was found that linoleic acid (a normal constituent of skin) greatly stimulated uptake of Lucifer Yellow and dextrans into the excretory/subtegumental region of 2-h-old schistosomula. This correlated with an increased uptake of membrane-impermeant propidium iodide at 37°C. Since increased uptake of propidium iodide occurs when membranes become permeable, the surface membrane could also be a pathway of transport of the membrane-impermeant molecules into the schistosomulum.
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27
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Ngiam N, Peltekova V, Engelberts D, Otulakowski G, Post M, Kavanagh BP. Early growth response-1 worsens ventilator-induced lung injury by up-regulating prostanoid synthesis. Am J Respir Crit Care Med 2010; 181:947-56. [PMID: 20110555 DOI: 10.1164/rccm.200908-1297oc] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE Ventilator-induced lung injury (VILI) is common and serious and may be mediated in part by prostanoids. We have demonstrated increased expression of the early growth response-1 (Egr1) gene by injurious ventilation, but whether-or how-such up-regulation contributes to injury is unknown. OBJECTIVES We sought to define the role of Egr1 in the pathogenesis of VILI. METHODS An in vivo murine model of VILI was used, and Egr1(+/+) (wild-type) and Egr1(-/-) mice were studied; the effects of prostaglandin E receptor subtype 1 (EP1) inhibition were assessed. MEASUREMENTS AND MAIN RESULTS Injurious ventilation caused lung injury in wild-type mice, but less so in Egr1(-/-) mice. The injury was associated with expression of EGR1 protein, which was localized to type II cells and macrophages and was concentrated in nuclear extracts. There was a concomitant increase in expression of phosphorylated p44/p42 mitogen-activated protein kinases. The prostaglandin E synthase (mPGES-1) gene has multiple EGR1 binding sites on its promoter, and induction of mPGES-1 mRNA (as well as the prostanoid product, PGE2) by injurious ventilation was highly dependent on the presence of the Egr1 gene. PGE2 mediates many lung effects via EP1 receptors, and EP1 blockade (with ONO-8713) lessened lung injury. CONCLUSIONS This is the first demonstration of a mechanism whereby expression of a novel gene (Egr1) can contribute to VILI via a prostanoid-mediated pathway.
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Affiliation(s)
- Nicola Ngiam
- Physiology and Experimental Medicine, Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, Canada M5G 1X8
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28
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Mechanobiology and Finite Element Analysis of Cellular Injury During Microbubble Flows. CELLULAR AND BIOMOLECULAR MECHANICS AND MECHANOBIOLOGY 2010. [DOI: 10.1007/8415_2010_25] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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29
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Yalcin HC, Hallow KM, Wang J, Wei MT, Ou-Yang HD, Ghadiali SN. Influence of cytoskeletal structure and mechanics on epithelial cell injury during cyclic airway reopening. Am J Physiol Lung Cell Mol Physiol 2009; 297:L881-91. [PMID: 19700641 DOI: 10.1152/ajplung.90562.2008] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Although patients with acute respiratory distress syndrome require mechanical ventilation, these ventilators often exacerbate the existing lung injury. For example, the cyclic closure and reopening of fluid-filled airways during ventilation can cause epithelial cell (EpC) necrosis and barrier disruption. Although much work has focused on minimizing the injurious mechanical forces generated during ventilation, an alternative approach is to make the EpC less susceptible to injury by altering the cell's intrinsic biomechanical/biostructural properties. In this study, we hypothesized that alterations in cytoskeletal structure and mechanics can be used to reduce the cell's susceptibility to injury during airway reopening. EpC were treated with jasplakinolide to stabilize actin filaments or latrunculin A to depolymerize actin and then exposed to cyclic airway reopening conditions at room temperature using a previously developed in vitro cell culture model. Actin stabilization did not affect cell viability but significantly improved cell adhesion primarily due to the development of more numerous focal adhesions. Surprisingly, actin depolymerization significantly improved both cell viability and cell adhesion but weakened focal adhesions. Optical tweezer based measurements of the EpC's micromechanical properties indicate that although latrunculin-treated cells are softer, they also have increased viscous damping properties. To further investigate the effect of "fluidization" on cell injury, experiments were also conducted at 37 degrees C. Although cells held at 37 degrees C exhibited no changes in cytoskeletal structure, they did exhibit increased viscous damping properties and improved cell viability. We conclude that fluidization of the actin cytoskeleton makes the EpC less susceptible to the injurious mechanical forces generated during cyclic airway reopening.
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Affiliation(s)
- H C Yalcin
- Mechanical Engineering and BioEngineering, Lehigh University, Bethlehem, PA, USA
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30
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Johnson LN, Koval M. Cross-talk between pulmonary injury, oxidant stress, and gap junctional communication. Antioxid Redox Signal 2009; 11:355-67. [PMID: 18816185 PMCID: PMC2933150 DOI: 10.1089/ars.2008.2183] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Gap junction channels interconnect several different types of cells in the lung, ranging from the alveolar epithelium to the pulmonary vasculature, each of which expresses a unique subset of gap junction proteins (connexins). Major lung functions regulated by gap junctional communication include coordination of ciliary beat frequency and inflammation. Gap junctions help enable the alveolus to regulate surfactant secretion as an integrated system, in which type I cells act as mechanical sensors that transmit calcium transients to type II cells. Thus, disruption of epithelial gap junctional communication, particularly during acute lung injury, can interfere with these processes and increase the severity of injury. Consistent with this, connexin expression is altered during lung injury, and connexin-deficiency has a negative impact on the injury response and lung-growth control. It has recently been shown that alcohol abuse is a significant risk factor associated with acute respiratory distress syndrome. Oxidant stress and hormone-signaling cascades in the lung induced by prolonged alcohol ingestion are discussed, as well as the effects of these pathways on connexin expression and function.
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Affiliation(s)
- Latoya N Johnson
- Division of Pulmonary, Allergy and Critical Care Medicine, and Emory Alcohol and Lung Biology Center, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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31
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Inhaled IL-10 reduces biotrauma and mortality in a model of ventilator-induced lung injury. Respir Med 2008; 103:463-70. [PMID: 19006658 DOI: 10.1016/j.rmed.2008.09.020] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2008] [Revised: 09/08/2008] [Accepted: 09/15/2008] [Indexed: 11/22/2022]
Abstract
BACKGROUND High-pressure ventilation induces barotrauma and pulmonary inflammation, thus leading to ventilator-induced lung injury (VILI). By limiting the pulmonal inflammation cascade the anti-inflammatory cytokine interleukin (IL)-10 may have protective effects. Via inhalation, IL-10 reaches the pulmonary system directly and in high concentrations. METHODS Thirty six male, anesthetized and mechanically ventilated Sprague-Dawley rats were randomly assigned to the following groups (n=9, each): SHAM: pressure controlled ventilation with p(max)=20cmH(2)O, PEEP=4; VILI: ventilator settings were changed for 20min to p(max)=45cmH(2)O, PEEP=0; IL-10(high): inhalation of 10microg/kg IL-10 prior to induction of VILI; and IL-10(low): inhalation of 1microg/kg IL-10 prior to induction of VILI. All groups were ventilated and observed for 4h. RESULTS High-pressure ventilation increased the concentrations of macrophage inflammatory protein (MIP)-2 and IL-1beta in bronchoalveolar lavage fluid (BALF) and plasma. This effect was reduced by the inhalation of IL-10 (10microg/kg). Additionally, IL-10 increased the animal survival time (78% vs. 22% 4-h mortality rate) and reduced NO-release from ex vivo cultured alveolar macrophages. Moreover, VILI-induced pulmonary heat shock protein-70 expression was reduced by IL-10 aerosol in a dose-dependent manner. Similarly, the activation of matrix metalloproteinase (MMP)-9 in BALF was reduced dose-dependently by IL-10. IL-10-treated animals showed a lower macroscopic lung injury score and less impairment of lung integrity and gas exchange. CONCLUSIONS Prophylactic inhalation of IL-10 improved survival and reduced lung injury in experimental VILI. Results indicate that this effect may be mediated by the inhibition of stress-induced inflammation and pulmonary biotrauma.
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Ghadiali SN, Gaver DP. Biomechanics of liquid-epithelium interactions in pulmonary airways. Respir Physiol Neurobiol 2008; 163:232-43. [PMID: 18511356 DOI: 10.1016/j.resp.2008.04.008] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2008] [Revised: 04/09/2008] [Accepted: 04/10/2008] [Indexed: 01/11/2023]
Abstract
The delicate structure of the lung epithelium makes it susceptible to surface tension induced injury. For example, the cyclic reopening of collapsed and/or fluid-filled airways during the ventilation of injured lungs generates hydrodynamic forces that further damage the epithelium and exacerbate lung injury. The interactions responsible for epithelial injury during airway reopening are fundamentally multiscale, since air-liquid interfacial dynamics affect global lung mechanics, while surface tension forces operate at the molecular and cellular scales. This article will review the current state-of-knowledge regarding the effect of surface tension forces on (a) the mechanics of airway reopening and (b) epithelial cell injury. Due to the complex nature of the liquid-epithelium system, a combination of computational and experimental techniques are being used to elucidate the mechanisms of surface-tension induced lung injury. Continued research is leading to an integrated understanding of the biomechanical and biological interactions responsible for cellular injury during airway reopening. This information may lead to novel therapies that minimize ventilation induced lung injury.
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Affiliation(s)
- Samir N Ghadiali
- Department of Mechanical Engineering and Mechanics, Bioengineering Program, Lehigh University, Bethlehem, PA 18015, USA.
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Acute Lung Injury: Acute Respiratory Distress Syndrome. MECHANICAL VENTILATION 2008. [PMCID: PMC7149661 DOI: 10.1016/b978-0-7216-0186-1.50008-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Abstract
Diabetic microangiopathy targets the lung as it does other organs. Even though respiratory dysfunction in most patients with diabetes is subclinical and rarely the presenting complaint, there are several reasons why pulmonary assessment is important: (1) Pulmonary function testing noninvasively quantifies physiological reserves in a large microvascular bed that is not clinically devastated by diabetes. (2) Subclinical loss of pulmonary reserves becomes overtly debilitating under conditions of stress, such as with aging, chronic hypoxia due to lung disease or high altitude exposure, or volume overload secondary to cardiac and renal failure. (3) Unlike myocardial or skeletal muscle function, pulmonary indices are largely independent of physical fitness. (4) Interpretation of pulmonary function indices is not complicated by secondary sequelae of diabetic end-organ failure or prior therapy. Lung function could provide useful measures of the progression of systemic microangiopathy. (5) Chronic use of inhaled insulin may affect long-term pulmonary function, while preexisting pulmonary dysfunction may alter the absorption and bioavailability of inhaled insulin. This review will discuss the changes in lung function observed in diabetes, their underlying mechanisms, and their physiological and clinical implications.
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Affiliation(s)
- Connie C W Hsia
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9034, USA.
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Mijailovich SM, Hamada K, Tsuda A. IL-8 Response of Cyclically Stretching Alveolar Epithelial Cells Exposed to Non-fibrous Particles. Ann Biomed Eng 2007; 35:582-94. [PMID: 17242997 DOI: 10.1007/s10439-006-9233-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2005] [Accepted: 11/13/2006] [Indexed: 10/23/2022]
Abstract
Using a cell stretcher device, we have previously shown that A549 cells exposed to asbestos fibers gave significantly increased cytokine responses (IL-8) when they were cyclically stretched [Tsuda, A., B. K. Stringer, S. M. Mijailovich, R. A. Rogers, K. Hamada, and M. L. Gray. Am. J. Respir. Cell Mol. Biol. 21(4):455-462, 1999]. In the present study, cell stretching experiments were performed using non-fibrous riebeckite particles, instead of fibrous particles. Riebeckite particles are ground asbestos fibers with the size of a few microns and non-fibrous shape, and are often used as "non-toxic" control particles in the studies of fibrous particle-induced pathogenesis. Although it is generally assumed that riebeckite particles do not elicit strong biological responses, in our studies in cyclically stretched cell cultures, the riebeckite particles coated with adhesion proteins induced significant IL-8 responses, but in static cell cultures the treatment with adhesion protein-coated riebeckite did not induce comparable cytokine responses. To interpret these data, we have developed a simple mathematical model of adhesive interactions between a cell layer and rigid fibrous/non-fibrous particles that were subjected to external tensile forces. The analysis showed that because of considerable dissimilarity in deformations (i.e., strain mismatch) between the cells and particles during breathing, the attachment of particles as small as 1 micro in size could induce significant mechanical forces on the cell surface receptors, which may trigger subsequent adverse cell response under dynamic stretching conditions.
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Affiliation(s)
- S M Mijailovich
- Physiology Program, Harvard School of Public Health, 665 Huntington Avenue, Boston, MA 02115, USA
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Fisher JL, Margulies SS. Modeling the effect of stretch and plasma membrane tension on Na+-K+-ATPase activity in alveolar epithelial cells. Am J Physiol Lung Cell Mol Physiol 2007; 292:L40-53. [PMID: 16891387 DOI: 10.1152/ajplung.00425.2005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
While a number of whole cell mechanical models have been proposed, few, if any, have focused on the relationship among plasma membrane tension, plasma membrane unfolding, and plasma membrane expansion and relaxation via lipid insertion. The goal of this communication is to develop such a model to better understand how plasma membrane tension, which we propose stimulates Na+-K+-ATPase activity but possibly also causes cell injury, may be generated in alveolar epithelial cells during mechanical ventilation. Assuming basic relationships between plasma membrane unfolding and tension and lipid insertion as the result of tension, we have captured plasma membrane mechanical responses observed in alveolar epithelial cells: fast deformation during fast cyclic stretch, slower, time-dependent deformation via lipid insertion during tonic stretch, and cell recovery after release from stretch. The model estimates plasma membrane tension and predicts Na+-K+-ATPase activation for a specified cell deformation time course. Model parameters were fit to plasma membrane tension, whole cell capacitance, and plasma membrane area data collected from the literature for osmotically swollen and shrunken cells. Predictions of membrane tension and stretch-stimulated Na+-K+-ATPase activity were validated with measurements from previous studies. As a proof of concept, we demonstrate experimentally that tonic stretch and consequent plasma membrane recruitment can be exploited to condition cells against subsequent cyclic stretch and hence mitigate stretch-induced responses, including stretch-induced cell death and stretch-induced modulation of Na+-K+-ATPase activity. Finally, the model was exercised to evaluate plasma membrane tension and potential Na+-K+-ATPase stimulation for an assortment of traditional and novel ventilation techniques.
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Affiliation(s)
- Jacob L Fisher
- Department of Bioengineering, University of Pennsylvania, 3320 Smith Walk, Philadelphia, PA 19104-6392, USA
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Nakos G, Batistatou A, Galiatsou E, Konstanti E, Koulouras V, Kanavaros P, Doulis A, Kitsakos A, Karachaliou A, Lekka ME, Bai M. Lung and 'end organ' injury due to mechanical ventilation in animals: comparison between the prone and supine positions. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2006; 10:R38. [PMID: 16507176 PMCID: PMC1550810 DOI: 10.1186/cc4840] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2005] [Revised: 01/25/2006] [Accepted: 02/03/2006] [Indexed: 02/06/2023]
Abstract
Introduction Use of the prone position in patients with acute lung injury improves their oxygenation. Most of these patients die from multisystem organ failure and not from hypoxia, however. Moreover, there is some evidence that the organ failure is caused by increased cell apoptosis. In the present study we therefore examined whether the position of the patients affects histological changes and apoptosis in the lung and 'end organs', including the brain, heart, diaphragm, liver, kidneys and small intestine. Methods Ten mechanically ventilated sheep with a tidal volume of 15 ml/kg body weight were studied for 90 minutes. Five sheep were placed in the supine position and five sheep were placed in the prone position during the experiment. Lung changes were analyzed histologically using a semiquantitative scoring system and the extent of apoptosis was investigated with the TUNEL method. Results In the supine position intra-alaveolar hemorrhage appeared predominantly in the dorsal areas, while the other histopathologic lesions were homogeneously distributed throughout the lungs. In the prone position, all histological changes were homogeneously distributed. A significantly higher score of lung injury was found in the supine position than in the prone position (4.63 ± 0.58 and 2.17 ± 0.19, respectively) (P < 0.0001). The histopathologic changes were accompanied by increased apoptosis (TUNEL method). In the supine position, the apoptotic index in the lung and in most of the 'end organs' was significantly higher compared with the prone position (all P < 0.005). Interestingly, the apoptotic index was higher in dorsal areas compared with ventral areas in both the prone and supine positions (P < 0.003 and P < 0.02, respectively). Conclusion Our results suggest that the prone position appears to reduce the severity and the extent of lung injury, and is associated with decreased apoptosis in the lung and 'end organs'.
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Affiliation(s)
- George Nakos
- Department of Intensive Care Unit, University Hospital of Ioannina, Greece
| | | | - Eftychia Galiatsou
- Department of Intensive Care Unit, University Hospital of Ioannina, Greece
| | - Eleonora Konstanti
- Department of Intensive Care Unit, University Hospital of Ioannina, Greece
| | | | | | - Apostolos Doulis
- Department of Intensive Care Unit, University Hospital of Ioannina, Greece
| | | | | | | | - Maria Bai
- Department of Pathology, University of Ioannina, Greece
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Abstract
Patients with severe acute respiratory distress syndrome who die usually succumb to multiorgan failure as opposed to hypoxia. Despite appropriate resuscitation, some patients' symptoms persist on a downward spiral, apparently propagated by an uncontained systemic inflammatory response. This phenomenon is not well understood. However, a novel hypothesis to explain this observation proposes that it is related to the life-saving ventilatory support used to treat the respiratory failure. According to this hypothesis, mechanical ventilation per se, by altering both the magnitude and the pattern of lung stretch, can cause changes in gene expression and/or cellular metabolism that ultimately can lead to the development of an overwhelming inflammatory response-even in the absence of overt structural damage. This mechanism of injury has been termed biotrauma. In this review we explore the biotrauma hypothesis, the causal relationship between biophysical injury and organ failure, and its implications for the future therapy and management of critically ill patients.
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Affiliation(s)
- Claudia C dos Santos
- Department of Medicine, St. Michael's Hospital, Toronto, Ontario M5B 1W8, Canada.
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Adkison JB, Miller GT, Weber DS, Miyahara T, Ballard ST, Frost JR, Parker JC. Differential responses of pulmonary endothelial phenotypes to cyclical stretch. Microvasc Res 2006; 71:175-84. [PMID: 16624338 DOI: 10.1016/j.mvr.2006.02.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2005] [Revised: 02/08/2006] [Accepted: 02/28/2006] [Indexed: 11/27/2022]
Abstract
Endothelial phenotypes derived from different pulmonary vascular segments have markedly different permeability response to inflammatory agonists, but their responses to mechanical strain have not been characterized. Therefore, we evaluated the effect of cyclical stretch on cell shape, cell membrane wounding, and junctional beta-catenin in rat pulmonary artery (RPAEC) and microvascular (RPMVEC) endothelial cell monolayers. After 24 h of 24% uniaxial strain at 40 cycles/min, RPAEC but not RPMVEC reoriented transverse to the axis of strain. Total beta-catenin increased in RPAEC but decreased in RPMVEC. Transient plasma membrane wounding was produced by cyclical biaxial strain of 34% or by scratching of monolayers with a needle and was indicated by retention of lysine fixable fluorescent 70 kDa dextran. Junctional beta-catenin was quantified by fluorescence intensity and image analysis. beta-catenin fluorescence was significantly lower in wounded cells than in adjacent uninjured cells in both phenotypes, and the decrease was significantly greater in RPAEC compared to RPMVEC in both scratched (57% vs. 30%) and stretched (55% vs. 37%) cells. Using immunoprecipitation, VE-cadherin-associated beta-catenin decreased significantly in RPAEC (61%) but E-cadherin-associated beta-catenin was not significantly decreased in RPMVEC after 34% biaxial cyclical strain. These data suggest that RPAEC more readily remodel cell-cell adhesions during cyclical stretch than RPMVEC and that a reduced intercellular adhesion adjacent to wounded cells could serve as transvascular leak sites in both phenotypes.
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Affiliation(s)
- Jarrod B Adkison
- Department of Physiology, MSB 3074, University of South Alabama, Mobile, 36688, USA
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Lionetti V, Lisi A, Patrucco E, De Giuli P, Milazzo MG, Ceci S, Wymann M, Lena A, Gremigni V, Fanelli V, Hirsch E, Ranieri VM. Lack of phosphoinositide 3-kinase-gamma attenuates ventilator-induced lung injury. Crit Care Med 2006; 34:134-41. [PMID: 16374167 DOI: 10.1097/01.ccm.0000190909.70601.2c] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE G protein-coupled receptors may up-regulate the inflammatory response elicited by ventilator-induced lung injury but also regulate cell survival via protein kinase B (Akt) and extracellular signal regulated kinases 1/2 (ERK1/2). The G protein-sensitive phosphoinositide-3-kinase gamma (PI3Kgamma) regulates several cellular functions including inflammation and cell survival. We explored the role of PI3Kgamma on ventilator-induced lung injury. DESIGN Prospective, randomized, experimental study. SETTING University animal research laboratory. SUBJECTS Wild-type (PI3Kgamma), knock-out (PI3Kgamma ), and kinase-dead (PI3Kgamma) mice. INTERVENTIONS Three ventilatory strategies (no stretch, low stretch, high stretch) were studied in an isolated, nonperfused model of acute lung injury (lung lavage) in PI3Kgamma, PI3Kgamma, and PI3Kgamma mice. MEASUREMENTS AND MAIN RESULTS Reduction in lung compliance, hyaline membrane formation, and epithelial detachment with high stretch were more pronounced in PI3Kgamma than in PI3Kgamma and PI3Kgamma (p < .01). Inflammatory cytokines and IkBalpha phosphorylation with high stretch did not differ among PI3Kgamma, PI3Kgamma, and PI3Kgamma. Apoptotic index (terminal deoxynucleotidyl transferase-mediated biotin-dUTP nick-end labeling) and caspase-3 (immunohistochemistry) with high stretch were larger (p < .01) in PI3Kgamma and PI3Kgamma than in PI3Kgamma. Electron microscopy showed that high stretch caused apoptotic changes in alveolar cells of PI3Kgamma mice whereas PI3Kgamma mice showed necrosis. Phosphorylation of Akt and ERK1/2 with high stretch was more pronounced in PI3Kgamma than in PI3Kgamma and PI3Kgamma (p < .01). CONCLUSIONS Silencing PI3Kgamma seems to attenuate functional and morphological consequences of ventilator-induced lung injury independently of inhibitory effects on cytokines release but through the enhancement of pulmonary apoptosis.
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Affiliation(s)
- Vincenzo Lionetti
- Dipartimento di Anestesiologia e Rianimazione, Ospedale S. Giovanni Battista-Molinette, Università di Torino, Torino, Italy
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Vlahakis NE, Hubmayr RD. Cellular stress failure in ventilator-injured lungs. Am J Respir Crit Care Med 2005; 171:1328-42. [PMID: 15695492 PMCID: PMC2718477 DOI: 10.1164/rccm.200408-1036so] [Citation(s) in RCA: 166] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2004] [Accepted: 01/21/2005] [Indexed: 01/10/2023] Open
Abstract
The clinical and experimental literature has unequivocally established that mechanical ventilation with large tidal volumes is injurious to the lung. However, uncertainty about the micromechanics of injured lungs and the numerous degrees of freedom in ventilator settings leave many unanswered questions about the biophysical determinants of lung injury. In this review we focus on experimental evidence for lung cells as injury targets and the relevance of these studies for human ventilator-associated lung injury. In vitro, the stress-induced mechanical interactions between matrix and adherent cells are important for cellular remodeling as a means for preventing compromise of cell structure and ultimately cell injury or death. In vivo, these same principles apply. Large tidal volume mechanical ventilation results in physical breaks in alveolar epithelial and endothelial plasma membrane integrity and subsequent triggering of proinflammatory signaling cascades resulting in the cytokine milieu and pathologic and physiologic findings of ventilator-associated lung injury. Importantly, though, alveolar cells possess cellular repair and remodeling mechanisms that in addition to protecting the stressed cell provide potential molecular targets for the prevention and treatment of ventilator-associated lung injury in the future.
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Affiliation(s)
- Nicholas E Vlahakis
- Thoracic Diseases Research Unit, Division of Pulmonary and Critical care Medicine, Department of Medicine, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
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Dietl P, Haller T. Exocytosis of lung surfactant: from the secretory vesicle to the air-liquid interface. Annu Rev Physiol 2005; 67:595-621. [PMID: 15709972 DOI: 10.1146/annurev.physiol.67.040403.102553] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Exocytosis is fundamental in biology and requires an orchestra of proteins and other constituents to fuse a vesicle with the plasma membrane. Although the molecular fusion machinery appears to be well conserved in evolution, the process itself varies considerably with regard to the diversity of physico-chemical and structural factors that govern the delay between stimulus and fusion, the expansion of the fusion pore, the release of vesicle content, and, finally, its extracellular dispersion. Exocytosis of surfactant is unique in many of these aspects. This review deals with the secretory pathway of pulmonary surfactant from the type II cell to the air-liquid interface, with focus on the distinct mechanisms and regulation of lamellar body (LB) fusion and release. We also discuss the fate of secreted material until it is rearranged into units that finally function to reduce the surface tension in the lung.
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Affiliation(s)
- Paul Dietl
- Department of General Physiology, University of Ulm, Ulm, D 89069, Germany.
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Sáenz-Valiente A, Piacentini E, Villagra García A, López-Aguilar J, Murias G, Hotchkiss J, Blanch Torra L. Papel de la microcirculación en el desarrollo de la lesión pulmonar aguda inducida por la ventilación mecánica. Med Intensiva 2005. [DOI: 10.1016/s0210-5691(05)74232-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Gattinoni L, Pesenti A. The concept of "baby lung". Intensive Care Med 2005; 31:776-84. [PMID: 15812622 DOI: 10.1007/s00134-005-2627-z] [Citation(s) in RCA: 461] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2005] [Accepted: 03/15/2005] [Indexed: 12/16/2022]
Abstract
BACKGROUND The "baby lung" concept originated as an offspring of computed tomography examinations which showed in most patients with acute lung injury/acute respiratory distress syndrome that the normally aerated tissue has the dimensions of the lung of a 5- to 6-year-old child (300-500 g aerated tissue). DISCUSSION The respiratory system compliance is linearly related to the "baby lung" dimensions, suggesting that the acute respiratory distress syndrome lung is not "stiff" but instead small, with nearly normal intrinsic elasticity. Initially we taught that the "baby lung" is a distinct anatomical structure, in the nondependent lung regions. However, the density redistribution in prone position shows that the "baby lung" is a functional and not an anatomical concept. This provides a rational for "gentle lung treatment" and a background to explain concepts such as baro- and volutrauma. CONCLUSIONS From a physiological perspective the "baby lung" helps to understand ventilator-induced lung injury. In this context, what appears dangerous is not the V(T)/kg ratio but instead the V(T)/"baby lung" ratio. The practical message is straightforward: the smaller the "baby lung," the greater is the potential for unsafe mechanical ventilation.
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Affiliation(s)
- Luciano Gattinoni
- Istituto di Anestesia e Rianimazione, Fondazione IRCCS, Ospedale Maggiore Policlinico, Mangiagalli, Regina Elena di Milano, Università degli Studi, Milan, Italy.
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Chess PR, O'Reilly MA, Toia L. Macroarray analysis reveals a strain-induced oxidant response in pulmonary epithelial cells. Exp Lung Res 2005; 30:739-53. [PMID: 15700550 DOI: 10.1080/01902140490517782] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Mechanical strain initiates a variety of responses in pulmonary epithelial cells. The signaling pathways and molecular alterations leading to these responses remain unclear To identify novel signal transduction pathways activated by strain, macroarray analysis was performed on strained pulmonary epithelial cells. Glutathione S-transferase (GST) pi, GST mu, and heat shock protein (HSP)-27 were increased by strain. Western blotting verified that increases in cDNA of these redox-related molecules resulted in an increase in protein. Phosphorylation of HSP-27 was increased after strain, further supporting the role of HSP-27 in strain-induced signal transduction. Strain-induced oxidative stress was verified with the oxidant-sensitive dye dichlorodihydrofluorescein diacetate.
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Affiliation(s)
- Patricia R Chess
- Department of Pediatrics, University of Rochester, Rochester, New York, USA.
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Dahlem P, Bos AP, Haitsma JJ, Schultz MJ, Meijers JCM, Lachmann B. Alveolar fibrinolytic capacity suppressed by injurious mechanical ventilation. Intensive Care Med 2005; 31:724-32. [PMID: 15754195 DOI: 10.1007/s00134-005-2588-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2004] [Accepted: 02/10/2005] [Indexed: 10/25/2022]
Abstract
OBJECTIVE To investigate the effect of mechanical ventilation on alveolar fibrinolytic capacity. DESIGN AND SETTING Randomized controlled animal study in 66 Sprague-Dawley rats. SUBJECTS AND INTERVENTIONS Test animals received intratracheal fibrinogen and thrombin instillations; six were killed immediately (fibrin controls), and the others were allocated to three ventilation groups (ventilation period: 225 min) differing in positive inspiratory pressure and positive end-expiratory pressure, respectively: group 1, 16 cmH2O and 5 cmH2O (n=17); group 2, 26 cmH2O and 5 cmH2O (n=16); group 3, 35 cmH2O and of 5 cmH2O (n=17). Ten animals that had not been ventilated served as healthy controls. MEASUREMENTS AND RESULTS After animals were killed, we measured D-dimers, plasminogen activator inhibitor (PAI) 1, and tumor necrosis factor alpha in the bronchoalveolar lavage fluid and calculated lung weight and pressure/volume (P/V) plots. The median D-dimer concentration (mg/l) decreased with increasing pressure amplitude (192 in group 1, IQR 119; 66 in group 2, IQR 107; 29 in group 3, IQR 30) while median PAI-1 (U/ml) increased (undetectable in group 1; 0.55 in group 2, IQR 4.55; 3.05 in group 3, IQR 4.85). PAI-1 level was correlated with increased lung weight per bodyweight (Spearman's rank correlation 0.708). Tumor necrosis factor alpha concentration was not correlated with PAI-1 level. CONCLUSIONS Alveolar fibrinolytic capacity is suppressed during mechanical ventilation with high pressure amplitudes due to local production of PAI-1.
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Affiliation(s)
- Peter Dahlem
- Pediatric Intensive Care Unit, Emma Children's Hospital, Academic Medical Centre, University of Amsterdam, Meibergdreef 9, 1100 DD Amsterdam, The Netherlands.
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Abstract
PURPOSE OF REVIEW Mechanical ventilation is the main supportive therapy for patients with acute respiratory distress syndrome. As with any therapy, mechanical ventilation has side effects and may induce lung injury. This review will focus on stretch-dependent activation of alveolar epithelial and endothelial cells and polymorphonuclear leukocytes, and apoptosis/necrosis balance. RECENT FINDINGS The past year has seen important research in the area of mechanotransduction and lung native immunity, suggesting further mechanisms of lung inflammation and injury in ventilator-induced lung injury. Research in the past year has also stressed the importance of inflammatory response by alveolar cells and role of polymorphonuclear leukocytes in stretch-induced lung injury and has suggested a role for apoptosis in the maintenance of the alveolar epithelium. SUMMARY The proportion of patients receiving protective ventilatory strategies remains modest. If efforts to minimize the iatrogenic consequences of mechanical ventilation are to succeed, there must be a greater understanding of the signal transduction mechanisms and the development of potential pharmacologic targets to modulate the molecular and cellular effects of lung stretch.
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Affiliation(s)
- Vincenzo Lionetti
- Laboratorio di Fisiologia e Biologia Molecolare, Classe di Scienze Sperimentali, Settore di Scienze Mediche, Pisa, Italy
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Balcells M, Fernández Suárez M, Vázquez M, Edelman ER. Cells in fluidic environments are sensitive to flow frequency. J Cell Physiol 2005; 204:329-35. [PMID: 15700266 DOI: 10.1002/jcp.20281] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Virtually all cells accommodate to their mechanical environment. In particular, cells subject to flow respond to rapid changes in fluid shear stress (SS), cyclic stretch (CS), and pressure. Recent studies have focused on the effect of pulsatility on cellular behavior. Since cells of many different tissue beds are constantly exposed to fluid flows over a narrow range of frequencies, we hypothesized that an intrinsic flow frequency that is optimal for determining cell phenotype exists. We report here that cells from various tissue beds (bovine aortic endothelial cells (BAEC), rat small intestine epithelial cells (RSIEC), and rat lung epithelial cells (RLEC)) proliferate maximally when cultured in a perfusion bioreactor under pulsatile conditions at a specific frequency, independent of the applied SS. Vascular endothelial and pulmonary epithelial cell proliferation peaked under 1 Hz pulsatile flow. In contrast, proliferation of gastrointestinal cells, which in their physiological context are subject to no flow or higher wavelength signal, was maximum at 0.125 Hz or under no flow. Moreover, exposure of BAEC to pulsatile flow of varying frequency influenced their nitric oxide synthase activity and prostacyclin production, which reached maximum values at 1 Hz. Notably, the "optimal" frequencies for the cell types examined correspond to the physiologic operating range of the organs from where they were initially derived. These findings suggest that frequency, independent of shear, is an essential determinant of cell response in pulsatile environments.
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Affiliation(s)
- Mercedes Balcells
- Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts, USA.
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Yoshikawa S, King JA, Lausch RN, Penton AM, Eyal FG, Parker JC. Acute ventilator-induced vascular permeability and cytokine responses in isolated and in situ mouse lungs. J Appl Physiol (1985) 2004; 97:2190-9. [PMID: 15531572 DOI: 10.1152/japplphysiol.00324.2004] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To determine the influence of experimental model and strain differences on the relationship of vascular permeability to inflammatory cytokine production after high peak inflation pressure (PIP) ventilation, we used isolated perfused mouse lung and intact mouse preparations of Balb/c and B6/129 mice ventilated at high and low PIP. Filtration coefficients in isolated lungs and bronchoalveolar lavage (BAL) albumin in intact mice increased within 20–30 min after initiation of high PIP in isolated Balb/c lungs and intact Balb/c, B6/129 wild-type, and p55 and p75 tumor necrosis factor (TNF) dual-receptor null mice. In contrast, the cytokine response was delayed and variable compared with the permeability response. In isolated Balb/c lungs ventilated with 25–27 cmH2O PIP, TNF-α, interleukin (IL)-1β, IL-1α, macrophage inflammatory protein (MIP)-2, and IL-6 concentrations in perfusate were markedly increased in perfusate at 2 and 4 h, but only MIP-2 was detectable in intact Balb/c mice using the same PIP. In intact wild-type and TNF dual-receptor null mice with ventilation at 45 cmH2O PIP, the MIP-2 and IL-6 levels in BAL were significantly increased after 2 h in both groups, but there were no differences between groups in the BAL albumin and cytokine concentrations or in lung wet-to-dry weight ratios. TNF-α was not be detected in BAL fluids in any group of intact mice. These results suggest that the alveolar hyperpermeability induced by high PIP ventilation occurs very rapidly and is initially independent of TNF-α participation and unlikely to depend on MIP-2 or IL-6.
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Affiliation(s)
- S Yoshikawa
- Dept. of Physiology, College of Medicine, University of South Alabama, Mobile, AL 36688, USA
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Gurkan F, Atamer Y, Ece A, Kocyigit Y, Tuzun H, Mete N. Serum leptin levels in asthmatic children treated with an inhaled corticosteroid. Ann Allergy Asthma Immunol 2004; 93:277-80. [PMID: 15478389 DOI: 10.1016/s1081-1206(10)61501-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Recent observations suggest the presence of an interaction between leptin and the inflammatory system; however, there is no adequate knowledge about the role of leptin in atopic states such as asthma. OBJECTIVES To evaluate the potential role of leptin in relation to bronchial asthma and inhaled corticosteroid therapy. METHODS Twenty-three children with mild-to-moderate, newly diagnosed asthma enrolled in this 2-period trial. The control group consisted of 20 age- and sex-matched children. Serum leptin levels were measured in patients at initiation and after 4 weeks of budesonide treatment and were compared with control group measurements. RESULTS Asthmatic children had higher mean +/- SD serum leptin levels at admission (19.3 +/- 5.1 ng/mL) than after budesonide treatment (10.6 +/- 1.6 ng/mL) and vs control group measurements (9.8 +/- 1.6 ng/mL) (P < .001). There was a significant correlation between serum leptin levels before and after budesonide treatment (r = 0.68; P = .007). Mean +/- SD body mass indices in patients and controls were 16.7 +/- 2.1 and 16.9 +/- 2.6 kg/m2, respectively. Serum leptin levels did not correlate with body mass indices before budesonide treatment in the study group (r = -0.13; P = .65) but correlated well after budesonide treatment (r = 0.58; P = .009) and in the control group (r = 0.65; P = .008). CONCLUSIONS The role of leptin elevation in children with asthma might be a regulatory mechanism rather than being etiologic, but a question may be raised whether it is possible that leptin may contribute to poor patient outcomes. Further research, both basic and clinical, is essential to explain the exact mechanism.
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Affiliation(s)
- Fuat Gurkan
- Department of Pediatrics, Dicle University Hospital, Medical Faculty, Diyarbakir, Turkey.
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