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Abstract
Pulmonary oedema (PO) is a common manifestation of acute heart failure (AHF) and is associated with a high-acuity presentation and with poor in-hospital outcomes. The clinical picture of PO is dominated by signs of pulmonary congestion, and its pathogenesis has been attributed predominantly to an imbalance in Starling forces across the alveolar-capillary barrier. However, recent studies have demonstrated that PO formation and resolution is critically regulated by active endothelial and alveolar signalling. PO represents a medical emergency and treatment should be individually tailored to the urgency of the presentation and acute haemodynamic characteristics. Although, the majority of patients admitted with PO rapidly improve as result of conventional intravenous (IV) therapies, treatment of PO remains largely opinion based as there is a general lack of good evidence to guide therapy. Furthermore, none of these therapies showed simultaneous benefit for symptomatic relief, haemodynamic improvement, increased survival and end-organ protection. Future research is required to develop innovative pharmacotherapies capable of relieving congestion while simultaneously preventing end-organ damage.
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Affiliation(s)
- Ovidiu Chioncel
- Institute of Emergency for Cardiovascular Diseases 'Prof. C.C. Iliescu', University of Medicine and Pharmacy Carol Davila, Bucuresti, Romania
| | - Sean P Collins
- Department of Emergency Medicine, Vanderbilt University, Nashville, Tennessee, US
| | | | - Mihai Gheorghiade
- Center for Cardiovascular Innovation, Northwestern University Feinberg School of Medicine, Chicago, Illinois, US
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2
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Bove PF, Dang H, Cheluvaraju C, Jones LC, Liu X, O'Neal WK, Randell SH, Schlegel R, Boucher RC. Breaking the in vitro alveolar type II cell proliferation barrier while retaining ion transport properties. Am J Respir Cell Mol Biol 2014; 50:767-76. [PMID: 24191670 DOI: 10.1165/rcmb.2013-0071oc] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Alveolar type (AT)I and ATII cells are central to maintaining normal alveolar fluid homeostasis. When disrupted, they contribute to the pathogenesis of acute lung injury (ALI) and acute respiratory distress syndrome. Research on ATII cells has been limited by the inability to propagate primary cells in vitro to study their specific functional properties. Moreover, primary ATII cells in vitro quickly transdifferentiate into nonproliferative "ATI-like" cells under traditional culture conditions. Recent studies have demonstrated that normal and tumor cells grown in culture with a combination of fibroblast (feeder cells) and a pharmacological Rho kinase inhibitor (Y-27632) exhibit indefinite cell proliferation that resembled a "conditionally reprogrammed cell" phenotype. Using this coculture system, we found that primary human ATII cells (1) proliferated at an exponential rate, (2) established epithelial colonies expressing ATII-specific and "ATI-like" mRNA and proteins after serial passage, (3) up-regulated genes important in cell proliferation and migration, and (4) on removal of feeder cells and Rho kinase inhibitor under air-liquid interface conditions, exhibited bioelectric and volume transport characteristics similar to freshly cultured ATII cells. Collectively, our results demonstrate that this novel coculture technique breaks the in vitro ATII cell proliferation barrier while retaining cell-specific functional properties. This work will allow for a significant increase in studies designed to elucidate ATII cell function with the goal of accelerating the development of novel therapies for alveolar diseases.
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Affiliation(s)
- Peter F Bove
- 1 Department of Medicine, Cystic Fibrosis/Pulmonary Research and Treatment Center and
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3
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4
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Abstract
Pulmonary edema is a problem of major clinical importance resulting from a persistent imbalance between forces that drive water into the airspace of the lung and the biological mechanisms for its removal. Here, we will first review the fundamental mechanisms implicated in the regulation of lung fluid homeostasis, namely, the Starling forces and the respiratory transepithelial sodium transport. Second, we will discuss the contribution of hypoxia to the perturbation of this fine balance and the role of such perturbations in the development of high-altitude pulmonary edema, a disease characterized by a very high morbidity and mortality. Finally, we will review possible interventions aimed to maintain/restore lung fluid homeostasis and their importance for the prevention/treatment of pulmonary edema.
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5
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Song W, Wei S, Zhou Y, Lazrak A, Liu G, Londino JD, Squadrito GL, Matalon S. Inhibition of lung fluid clearance and epithelial Na+ channels by chlorine, hypochlorous acid, and chloramines. J Biol Chem 2010; 285:9716-9728. [PMID: 20106988 DOI: 10.1074/jbc.m109.073981] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
We investigated the mechanisms by which chlorine (Cl(2)) and its reactive byproducts inhibit Na(+)-dependent alveolar fluid clearance (AFC) in vivo and the activity of amiloride-sensitive epithelial Na(+) channels (ENaC) by measuring AFC in mice exposed to Cl(2) (0-500 ppm for 30 min) and Na(+) and amiloride-sensitive currents (I(Na) and I(amil), respectively) across Xenopus oocytes expressing human alpha-, beta-, and gamma-ENaC incubated with HOCl (1-2000 microm). Both Cl(2) and HOCl-derived products decreased AFC in mice and whole cell and single channel I(Na) in a dose-dependent manner; these effects were counteracted by serine proteases. Mass spectrometry analysis of the oocyte recording medium identified organic chloramines formed by the interaction of HOCl with HEPES (used as an extracellular buffer). In addition, chloramines formed by the interaction of HOCl with taurine or glycine decreased I(Na) in a similar fashion. Preincubation of oocytes with serine proteases prevented the decrease of I(Na) by HOCl, whereas perfusion of oocytes with a synthetic 51-mer peptide corresponding to the putative furin and plasmin cleaving segment in the gamma-ENaC subunit restored the ability of HOCl to inhibit I(Na). Finally, I(Na) of oocytes expressing wild type alpha- and gamma-ENaC and a mutant form of beta ENaC (S520K), known to result in ENaC channels locked in the open position, were not altered by HOCl. We concluded that HOCl and its reactive intermediates (such as organic chloramines) inhibit ENaC by affecting channel gating, which could be relieved by proteases cleavage.
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Affiliation(s)
- Weifeng Song
- Departments of Anesthesiology, Birmingham, Alabama 35205; Centers for Pulmonary Injury and Repair, Birmingham, Alabama 35205
| | - Shipeng Wei
- Departments of Anesthesiology, Birmingham, Alabama 35205; Centers for Pulmonary Injury and Repair, Birmingham, Alabama 35205
| | - Yongjian Zhou
- Departments of Anesthesiology, Birmingham, Alabama 35205
| | - Ahmed Lazrak
- Departments of Anesthesiology, Birmingham, Alabama 35205; Centers for Pulmonary Injury and Repair, Birmingham, Alabama 35205
| | - Gang Liu
- Centers for Pulmonary Injury and Repair, Birmingham, Alabama 35205; Medicine, Birmingham, Alabama 35205
| | - James D Londino
- Departments of Anesthesiology, Birmingham, Alabama 35205; Centers for Pulmonary Injury and Repair, Birmingham, Alabama 35205
| | - Giuseppe L Squadrito
- Centers for Pulmonary Injury and Repair, Birmingham, Alabama 35205; Environmental Health Sciences, Schools of Medicine and Public Health, Birmingham, Alabama 35205; Free Radical Biology, University of Alabama at Birmingham, Birmingham, Alabama 35205
| | - Sadis Matalon
- Departments of Anesthesiology, Birmingham, Alabama 35205; Centers for Pulmonary Injury and Repair, Birmingham, Alabama 35205; Medicine, Birmingham, Alabama 35205; Free Radical Biology, University of Alabama at Birmingham, Birmingham, Alabama 35205.
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6
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Abstract
Flash pulmonary edema (FPE) is a general clinical term used to describe a particularly dramatic form of acute decompensated heart failure. Well-established risk factors for heart failure such as hypertension, coronary ischemia, valvular heart disease, and diastolic dysfunction are associated with acute decompensated heart failure as well as with FPE. However, endothelial dysfunction possibly secondary to an excessive activity of renin-angiotensin-aldosterone system, impaired nitric oxide synthesis, increased endothelin levels, and/or excessive circulating catecholamines may cause excessive pulmonary capillary permeability and facilitate FPE formation. Renal artery stenosis particularly when bilateral has been identified has a common cause of FPE. Lack of diurnal variation in blood pressure and a widened pulse pressure have been identified as risk factors for FPE. This review is an attempt to delineate clinical and pathophysiological mechanisms responsible for FPE and to distinguish pathophysiologic, clinical, and therapeutic aspects of FPE from those of acute decompensated heart failure.
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Affiliation(s)
- Stefano F Rimoldi
- Swiss Cardiovascular Center Bern, University Hospital, Bern, Switzerland.
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7
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Eaton DC, Helms MN, Koval M, Bao HF, Jain L. The contribution of epithelial sodium channels to alveolar function in health and disease. Annu Rev Physiol 2009; 71:403-23. [PMID: 18831683 DOI: 10.1146/annurev.physiol.010908.163250] [Citation(s) in RCA: 141] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Amiloride-sensitive epithelial sodium channels (ENaC) play an important role in lung sodium transport. Sodium transport is closely regulated to maintain an appropriate fluid layer on the alveolar surface. Both alveolar type I and II cells have several different sodium-permeable channels in their apical membranes that play a role in normal lung physiology and pathophysiology. In many epithelial tissues, ENaC is formed from three subunit proteins: alpha, beta, and gamma ENaC. Part of the diversity of sodium-permeable channels in lung arises from assembling different combinations of these subunits to form channels with different biophysical properties and different mechanisms for regulation. Thus, lung epithelium has enormous flexibility to alter the magnitude of salt and water transport. In lung, ENaC is regulated by many transmitter and hormonal agents. Regulation depends upon the type of sodium channel but involves controlling the number of apical channels and/or the activity of individual channels.
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Affiliation(s)
- Douglas C Eaton
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
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8
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Sartori C, Allemann Y, Scherrer U. Pathogenesis of pulmonary edema: learning from high-altitude pulmonary edema. Respir Physiol Neurobiol 2007; 159:338-49. [PMID: 17532272 DOI: 10.1016/j.resp.2007.04.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2006] [Revised: 04/05/2007] [Accepted: 04/10/2007] [Indexed: 01/07/2023]
Abstract
Pulmonary edema is a problem of major clinical importance resulting from a persistent imbalance between forces that drive water into the airspace of the lung and the biological mechanisms for its removal. Here, we will review the fundamental mechanisms implicated in the regulation of alveolar fluid homeostasis. We will then describe the perturbations of pulmonary fluid homeostasis implicated in the pathogenesis of pulmonary edema in conditions associated with increased pulmonary capillary pressure, namely cardiogenic pulmonary edema and high-altitude pulmonary edema (HAPE), with particular emphasis on the latter that has provided important new insight into underlying mechanisms of pulmonary edema. We will provide evidence that impaired pulmonary endothelial and epithelial nitric oxide synthesis and/or bioavailability may represent a central underlying defect predisposing to exaggerated hypoxic pulmonary vasoconstriction, and, in turn, capillary stress failure and alveolar fluid flooding. We will then demonstrate that exaggerated pulmonary hypertension, while possibly a prerequisite, may not always be sufficient to cause HAPE, and how defective alveolar fluid clearance may represent a second important pathogenic mechanism. Finally, we will outline, how this new insight gained from studies in HAPE, may be translated into the management of pulmonary edema and hypoxemia related disease states in general.
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Affiliation(s)
- Claudio Sartori
- Department of Internal Medicine and the Botnar Center for Extreme Medicine, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
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9
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Simon BA, Easley RB, Grigoryev DN, Ma SF, Ye SQ, Lavoie T, Tuder RM, Garcia JGN. Microarray analysis of regional cellular responses to local mechanical stress in acute lung injury. Am J Physiol Lung Cell Mol Physiol 2006; 291:L851-61. [PMID: 16782753 DOI: 10.1152/ajplung.00463.2005] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Human acute lung injury is characterized by heterogeneous tissue involvement, leading to the potential for extremes of mechanical stress and tissue injury when mechanical ventilation, required to support critically ill patients, is employed. Our goal was to establish whether regional cellular responses to these disparate local mechanical conditions could be determined as a novel approach toward understanding the mechanism of development of ventilator-associated lung injury. We utilized cross-species genomic microarrays in a unilateral model of ventilator-associated lung injury in anesthetized dogs to assess regional cellular responses to local mechanical conditions that potentially contribute pathogenic mechanisms of injury. Highly significant regional differences in gene expression were observed between lung apex/base regions as well as between gravitationally dependent/nondependent regions of the base, with 367 and 1,544 genes differentially regulated between these regions, respectively. Major functional groupings of differentially regulated genes included inflammation and immune responses, cell proliferation, adhesion, signaling, and apoptosis. Expression of genes encoding both acute lung injury-associated inflammatory cytokines and protective acute response genes were markedly different in the nondependent compared with the dependent regions of the lung base. We conclude that there are significant differences in the local responses to stress within the lung, and consequently, insights into the cellular responses that contribute to ventilator-associated lung injury development must be sought in the context of the mechanical heterogeneity that characterizes this syndrome.
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Affiliation(s)
- Brett A Simon
- Department of Anesthesiology and Critical Medicine, Tower 711, Johns Hopkins Hospital, Baltimore, MD 21287-8711, USA.
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Weidner WJ, Waddell DS, Furlow JD. Measurement of the filtration coefficient (Kfc) in the lung of Gallus domesticus and the effects of increased microvascular permeability. J Comp Physiol B 2006; 176:567-74. [PMID: 16538461 DOI: 10.1007/s00360-006-0079-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2005] [Revised: 01/13/2006] [Accepted: 03/01/2006] [Indexed: 10/24/2022]
Abstract
The filtration coefficient (Kfc) is a sensitive measure of microvascular hydraulic conductivity and has been reported for the alveolar lungs of many mammalian species, but not for the parabronchial avian lung. This study reports the Kfc in the isolated lungs of normal chickens and in the lungs of chickens given the edemogenic agents oleic acid (OA) or dimethyl amiloride (DMA). The control Kfc =0.04+/-0.01 ml min(-1) kPa(-1) g(-1). This parameter increased significantly following the administration of both OA (0.12+/-0.02 ml min(-1) kPa(-1) g(-1)) and DMA (0.07+/-0.01 ml min kPa(-1) g(-1)). As endothelial cadherins are thought to play a role in the dynamic response to acute lung injury, we utilized Western blot analysis to assess lung cadherin content and Northern blot analysis to assess pulmonary vascular endothelial (VE) cadherin expression following drug administration. Lung cadherin content decreases markedly following DMA, but not OA administration. VE cadherin expression increases as a result of DMA treatment, but is unchanged following OA. Our results suggest that the permeability characteristics of the avian lung are more closely consistent with those of the mammalian rather than the reptilian lung, and, that cadherins may play a significant role in the response to acute increases in avian pulmonary microvascular permeability.
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Affiliation(s)
- W Jeffrey Weidner
- Section of Neurobiology, Physiology, and Behavior, College of Biological Sciences, University of California, Davis, CA 95616, USA.
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11
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Taguchi N, Niisato N, Sawabe Y, Miyazaki H, Hirai Y, Marunaka Y. Benzamil, a blocker of epithelial Na(+) channel-induced upregulation of artery oxygen pressure level in acute lung injury rabbit ventilated with high frequency oscillation. Biochem Biophys Res Commun 2005; 327:915-9. [PMID: 15649432 DOI: 10.1016/j.bbrc.2004.12.098] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2004] [Indexed: 11/20/2022]
Abstract
The epithelial Na(+) transport via an epithelial Na(+) channel (ENaC) expressed in the lung epithelium would play a key role in recovery from lung edema at acute lung injury by removing the fluid in lung luminal space. The lung edema causes dysfunction of gas exchange, decreasing oxygen pressure level of artery [P(aO(2))]. To study if ENaC plays a key role in recovering P(aO(2)) from a decreased level to a normal one in acute lung injury, we applied benzamil (20microM, a specific blocker of ENaC) to the lung luminal space in acute lung injury treated with high frequency oscillation ventilation (HFOV) that is a lung-protective ventilation with a lower tidal volume and a smaller pressure swing than conventional mechanical ventilation (CMV). Benzamil facilitated the recovery of P(aO(2)) in acutely injured lung with HFOV but not CMV. The observation suggests that in acutely injured lung treated with HFOV an ENaC blocker, benzamil, can be applied as a therapeutic drug for acute lung injury combing with HFOV.
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Affiliation(s)
- Nobuko Taguchi
- Department of Molecular Cell Physiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
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12
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Looney MR, Sartori C, Chakraborty S, James PF, Lingrel JB, Matthay MA. Decreased expression of both the alpha1- and alpha2-subunits of the Na-K-ATPase reduces maximal alveolar epithelial fluid clearance. Am J Physiol Lung Cell Mol Physiol 2005; 289:L104-10. [PMID: 15781423 DOI: 10.1152/ajplung.00464.2004] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Impaired epithelial sodium channel function predisposes to delayed resorption of pulmonary edema and more severe experimental lung injury, whereas even a small fraction of the normal Na-K-ATPase activity is thought to be sufficient to maintain normal ion transport. However, direct proof is lacking. Therefore, we studied baseline and cAMP stimulated alveolar fluid clearance (AFC) in mice with a 50% decrease in lung protein expression of the alpha(1)- and/or alpha(2)-subunit of the Na-K-ATPase. There was no difference in basal and stimulated AFC in alpha(1)(+/-) or alpha(2)(+/-) mice compared with wild-type littermates. Also, the compound heterozygous mice (alpha(1)(+/-)/alpha(2)(+/-)) had normal basal AFC. However, the combined alpha(1)(+/-)/alpha(2)(+/-) mice showed a significant decrease in cAMP-stimulated AFC compared with wild-type littermates (11.1 +/- 1.0 vs. 14.9 +/- 1.8%/30 min, P < 0.001). When exposed to 96 h of >95% hyperoxia, the decrease in stimulated AFC in the alpha(1)(+/-)/alpha(2)(+/-) mice was not associated with more lung edema compared with wild-type littermates (lung wet-to-dry weight ratio 6.6 +/- 0.9 vs. 5.9 +/- 1.1, respectively; P = not significant). Thus a 50% decrease in protein expression of the alpha(1)- or alpha(2)-subunits of the Na-K-ATPase does not impair basal or stimulated AFC. However, a 50% protein reduction in both the alpha(1)- and alpha(2)-subunits of the Na-K-ATPase produces a submaximal stimulated AFC, suggesting a synergistic role for alpha(1)- and alpha(2)-subunits in cAMP-dependent alveolar epithelial fluid clearance.
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Affiliation(s)
- Mark R Looney
- Cardiovascular Research Institute and the Department of Medicine and Anesthesia, University of California, San Francisco, 94143-0130, USA.
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Qiao R, Zhou B, Harboe-Schmidt E, Kasahara N, Kim KJ, Liebler JM, Crandall ED, Borok Z. Subunit-specific coordinate upregulation of sodium pump activity in alveolar epithelial cells by lentivirus-mediated gene transfer. Hum Gene Ther 2004; 15:457-68. [PMID: 15144576 DOI: 10.1089/10430340460745784] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Resolution of alveolar edema depends on active ion transport by sodium pumps located on the basolateral surface of alveolar epithelial cells (AECs), suggesting that upregulation of sodium pump activity may facilitate clearance of edema fluid. We have investigated the use of lentiviral vectors to augment sodium pump activity via gene transfer of sodium pump subunits to AECs. Full-length cDNA for the alpha(1) or beta(1) subunit of rat Na(+),K(+)-ATPase was cloned into the lentiviral vector pRRLsin.hCMV.IRES.EGFP. Rat AECs in primary culture were transduced on day 4 with lentiviral vectors pseudotyped with vesicular stomatitis virus glycoprotein G. Transduction with lentiviral vectors encoding either alpha(1) subunit (Lenti-alpha(1)-EGFP) or beta(1) subunit (Lenti-beta(1)-EGFP) led to dose-dependent increases in mRNA and protein for the corresponding subunit. Transduction with Lenti-beta(1)-EGFP was accompanied by coordinate upregulation of endogenous alpha(1) expression, whereas endogenous beta(1) expression was unchanged after transduction with Lenti-alpha(1)-EGFP. Consistent with these findings, transduction with Lenti-beta(1)-EGFP, but not Lenti-alpha(1)-EGFP, led to augmentation of sodium pump activity as a result of increases in Na(+),K(+)-ATPase holoenzyme. Sodium pump alpha(2) subunit and sodium channel protein did not change after Lenti-beta(1)-EGFP transduction. These results demonstrate that overall sodium pump activity can be efficiently upregulated in AECs specifically via gene transfer of the sodium pump beta(1) subunit and support the feasibility of lentivirus-mediated gene transfer to augment alveolar fluid clearance.
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Affiliation(s)
- Renli Qiao
- Division of Pulmonary and Critical Care Medicine, Will Rogers Institute of Pulmonary Research Center, University of Southern California, Los Angeles, CA 90033, USA.
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14
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Egli M, Duplain H, Lepori M, Cook S, Nicod P, Hummler E, Sartori C, Scherrer U. Defective respiratory amiloride-sensitive sodium transport predisposes to pulmonary oedema and delays its resolution in mice. J Physiol 2004; 560:857-65. [PMID: 15308680 PMCID: PMC1665279 DOI: 10.1113/jphysiol.2004.066704] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Pulmonary oedema results from an imbalance between the forces driving fluid into the airspace and the biological mechanisms for its removal. In mice lacking the alpha-subunit of the amiloride-sensitive sodium channel (alphaENaC(-/-)), impaired sodium transport-mediated lung liquid clearance at birth results in neonatal death. Transgenic expression of alphaENaC driven by a cytomegalovirus (CMV) promoter (alphaENaC(-/-)Tg+) rescues the lethal pulmonary phenotype, but only partially restores respiratory sodium transport in vitro. To test whether this may also be true in vivo, and to assess the functional consequences of this defect on experimental pulmonary oedema, we measured respiratory transepithelial potential difference (PD) and alveolar fluid clearance (AFC), and quantified pulmonary oedema during experimental acute lung injury in these mice. Both respiratory PD and AFC were roughly 50% lower (P < 0.01) in alphaENaC(-/-)Tg+ than in control mice. This impairment was associated with a significantly larger increase of the wet/dry lung weight ratio in alphaENaC(-/-)Tg+ than in control mice, both after exposure to hyperoxia and thiourea. Moreover, the rate of resolution of thiourea-induced pulmonary oedema was more than three times slower (P < 0.001) in alphaENaC(-/-)Tg+ mice. alphaENaC(-/-)Tg+ mice represent the first model of a constitutively impaired respiratory transepithelial sodium transport, and provide direct evidence that this impairment facilitates pulmonary oedema in conscious freely moving animals. These data in mice strengthen indirect evidence provided by clinical studies, suggesting that defective respiratory transepithelial sodium transport may also facilitate pulmonary oedema in humans.
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Affiliation(s)
- Marc Egli
- Department of Internal Medicine, Centre Hospitalier Universitaire Vaudois, CH-1011 Lausanne, Switzerland
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Groshaus HE, Manocha S, Walley KR, Russell JA. Mechanisms of beta-receptor stimulation-induced improvement of acute lung injury and pulmonary edema. Crit Care 2004; 8:234-42. [PMID: 15312205 PMCID: PMC522843 DOI: 10.1186/cc2875] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Acute lung injury (ALI) and the acute respiratory distress syndrome are complex syndromes because both inflammatory and coagulation cascades cause lung injury. Transport of salt and water, repair and remodeling of the lung, apoptosis, and necrosis are additional important mechanisms of injury. Alveolar edema is cleared by active transport of salt and water from the alveoli into the lung interstitium by complex cellular mechanisms. Beta-2 agonists act on the cellular mechanisms of pulmonary edema clearance as well as other pathways relevant to repair in ALI. Numerous studies suggest that the beneficial effects of beta-2 agonists in ALI include at least enhanced fluid clearance from the alveolar space, anti-inflammatory actions, and bronchodilation. The purposes of the present review are to consider the effects of beta agonists on three mechanisms of improvement of lung injury: edema clearance, anti-inflammatory effects, and bronchodilation. This update reviews specifically the evidence on the effects of beta-2 agonists in human ALI and in models of ALI. The available evidence suggests that beta-2 agonists may be efficacious therapy in ALI. Further randomized controlled trials of beta agonists in pulmonary edema and in acute lung injury are necessary.
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Affiliation(s)
- Horacio E Groshaus
- Critical Care Research Laboratories, St Paul's Hospital and University of British Columbia, Vancouver, British Columbia, Canada
| | - Sanjay Manocha
- Critical Care Research Laboratories, St Paul's Hospital and University of British Columbia, Vancouver, British Columbia, Canada
| | - Keith R Walley
- Critical Care Research Laboratories, St Paul's Hospital and University of British Columbia, Vancouver, British Columbia, Canada
| | - James A Russell
- Critical Care Research Laboratories, St Paul's Hospital and University of British Columbia, Vancouver, British Columbia, Canada
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Qiao R, Zhou B, Liebler JM, Li X, Crandall ED, Borok Z. Identification of three genes of known function expressed by alveolar epithelial type I cells. Am J Respir Cell Mol Biol 2003; 29:98-105. [PMID: 12600825 DOI: 10.1165/rcmb.2002-0196oc] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
To identify genes of known function expressed by type I (AT1) cells, changes in gene expression during transdifferentiation of alveolar epithelial cells (AEC) in primary culture from type II (AT2) to type I-like cell phenotype were evaluated. Total RNA from AEC on Day 0 or Day 8 was hybridized to a rat microarray for screening. Eight upregulated genes on Day 8 were selected for further investigation. Northern analysis confirmed upregulation of three of these genes, PAI-1, P2X4, and P15INK4B. The corresponding proteins were evaluated in cultured AEC and results correlated with expression in AT1 cells. In AEC monolayers, all three proteins increased between Day 1 and Day 8. In mixed populations of freshly isolated rat lung cells, concurrent labeling with the AT1 cell-specific antibody, VIIIB2, localized these proteins to AT1 cells. In whole lung, all three proteins were detected in alveolar epithelium in a location consistent with expression in AT1 cells. Identification of novel AT1 cell genes of known function suggests an active role for AT1 cells in alveolar homeostasis. Furthermore, expression of these gene products in AT1-like cells, in freshly isolated AT1 cells, and AT1 cells in whole lung indicates that AT1-like cells reflect many of the properties of AT1 cells in situ.
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Affiliation(s)
- Renli Qiao
- Division of Pulmonary and Critical Care Medicine, University of Southern California, Los Angeles, CA 90033, USA.
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17
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Abstract
High-altitude illness is the collective term for acute mountain sickness (AMS), high-altitude cerebral oedema (HACE), and high-altitude pulmonary oedema (HAPE). The pathophysiology of these syndromes is not completely understood, although studies have substantially contributed to the current understanding of several areas. These areas include the role and potential mechanisms of brain swelling in AMS and HACE, mechanisms accounting for exaggerated pulmonary hypertension in HAPE, and the role of inflammation and alveolar-fluid clearance in HAPE. Only limited information is available about the genetic basis of high-altitude illness, and no clear associations between gene polymorphisms and susceptibility have been discovered. Gradual ascent will always be the best strategy for preventing high-altitude illness, although chemoprophylaxis may be useful in some situations. Despite investigation of other agents, acetazolamide remains the preferred drug for preventing AMS. The next few years are likely to see many advances in the understanding of the causes and management of high-altitude illness.
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18
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O'Grady SM, Lee SY. Chloride and potassium channel function in alveolar epithelial cells. Am J Physiol Lung Cell Mol Physiol 2003; 284:L689-700. [PMID: 12676759 DOI: 10.1152/ajplung.00256.2002] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Electrolyte transport across the adult alveolar epithelium plays an important role in maintaining a thin fluid layer along the apical surface of the alveolus that facilitates gas exchange across the epithelium. Most of the work published on the transport properties of alveolar epithelial cells has focused on the mechanisms and regulation of Na(+) transport and, in particular, the role of amiloride-sensitive Na(+) channels in the apical membrane and the Na(+)-K(+)-ATPase located in the basolateral membrane. Less is known about the identity and role of Cl(-) and K(+) channels in alveolar epithelial cells, but studies are revealing important functions for these channels in regulation of alveolar fluid volume and ionic composition. The purpose of this review is to examine previous work published on Cl(-) and K(+) channels in alveolar epithelial cells and to discuss the conclusions and speculations regarding their role in alveolar cell transport function.
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Affiliation(s)
- Scott M O'Grady
- Department of Physiology, University of Minnesota, St. Paul, Minnesota 55108, USA.
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Groeneveld ABJ. Vascular pharmacology of acute lung injury and acute respiratory distress syndrome. Vascul Pharmacol 2002; 39:247-56. [PMID: 12747964 DOI: 10.1016/s1537-1891(03)00013-2] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) following sepsis, major trauma and surgery are leading causes of respiratory insufficiency, warranting artificial ventilation in the intensive care unit. It is caused by an inflammatory reaction in the lung upon exogenous or endogenous etiologies eliciting proinflammatory factors, and results in increased alveolocapillary permeability and protein-rich alveolar edema. The interstitial and alveolar inflammation and edema alter ventilation perfusion matching, gas exchange and mechanical properties of the lung. The current therapy of the condition is supportive, paying careful attention to fluid balance, relieving the increased work of breathing and improving gas exchange by mechanical ventilation, but in vitro, animal and some clinical research is done to evaluate the value of anti-inflammatory therapies on morbidity and outcome, including inflammatory cell-stabilizing corticosteroids, xanthine derivates, prostanoids and inhibitors, O(2) radical scavenging factors such as N-acetylcysteine, surfactant replacement, vasodilators including inhaled nitric oxide, vasoconstrictors such as almitrine, and others. None of these compounds has been proven to benefit survival in patients, however, even though carrying a physiologic benefit, except perhaps for steroids that may improve outcome in the later stage of ARDS. This partly relates to the difficulty to assess the lung injury at the bedside, to the multifactorial pathogenesis and the severity of comorbidity, adversely affecting survival.
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Affiliation(s)
- A B Johan Groeneveld
- Department of Intensive Care, Vrije Universiteit Medical Centre, De Boelelaan 1117, 1081 HV, Amsterdam, The Netherlands.
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Cruden NLM, Newby DE, Webb DJ. Salmeterol for the prevention of high-altitude pulmonary edema. N Engl J Med 2002; 347:1282-5; author reply 1282-5. [PMID: 12393831 DOI: 10.1056/nejm200210173471618] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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