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Harvey BJ, McElvaney NG. Sex differences in airway disease: estrogen and airway surface liquid dynamics. Biol Sex Differ 2024; 15:56. [PMID: 39026347 PMCID: PMC11264786 DOI: 10.1186/s13293-024-00633-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Accepted: 07/03/2024] [Indexed: 07/20/2024] Open
Abstract
Biological sex differences exist for many airway diseases in which females have either worse or better health outcomes. Inflammatory airway diseases such as cystic fibrosis (CF) and asthma display a clear male advantage in post-puberty while a female benefit is observed in asthma during the pre-puberty years. The influence of menstrual cycle stage and pregnancy on the frequency and severity of pulmonary exacerbations in CF and asthma point to a role for sex steroid hormones, particularly estrogen, in underpinning biological sex differences in these diseases. There are many ways by which estrogen may aggravate asthma and CF involving disturbances in airway surface liquid (ASL) dynamics, inappropriate hyper-immune and allergenic responses, as well as exacerbation of pathogen virulence. The deleterious effect of estrogen on pulmonary function in CF and asthma contrasts with the female advantage observed in airway diseases characterised by pulmonary edema such as pneumonia, acute respiratory distress syndrome (ARDS) and COVID-19. Airway surface liquid hypersecretion and alveolar flooding are hallmarks of ARDS and COVID-19, and contribute to the morbidity and mortality of severe forms of these diseases. ASL dynamics encompasses the intrinsic features of the thin lining of fluid covering the airway epithelium which regulate mucociliary clearance (ciliary beat, ASL height, volume, pH, viscosity, mucins, and channel activating proteases) in addition to innate defence mechanisms (pathogen virulence, cytokines, defensins, specialised pro-resolution lipid mediators, and metabolism). Estrogen regulation of ASL dynamics contributing to biological sex differences in CF, asthma and COVID-19 is a major focus of this review.
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Affiliation(s)
- Brian J Harvey
- Faculty of Medicine and Health Sciences, Royal College of Surgeons in Ireland, 126 St Stephens Green, Dublin 2, Ireland.
- Department of Medicine, RCSI ERC, Beaumont Hospital, Dublin 2, Ireland.
| | - Noel G McElvaney
- Faculty of Medicine and Health Sciences, Royal College of Surgeons in Ireland, 126 St Stephens Green, Dublin 2, Ireland
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2
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Meunier É, Aubin vega M, Adam D, Privé A, Mohammad Nezhady MA, Lahaie I, Quiniou C, Chemtob S, Brochiero E. Evaluation of interleukin-1 and interleukin-6 receptor antagonists in a murine model of acute lung injury. Exp Physiol 2024; 109:966-979. [PMID: 38594909 PMCID: PMC11140168 DOI: 10.1113/ep091682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Accepted: 03/12/2024] [Indexed: 04/11/2024]
Abstract
The acute exudative phase of acute respiratory distress syndrome (ARDS), a severe form of respiratory failure, is characterized by alveolar damage, pulmonary oedema, and an exacerbated inflammatory response. There is no effective treatment for this condition, but based on the major contribution of inflammation, anti-inflammatory strategies have been evaluated in animal models and clinical trials, with conflicting results. In COVID-19 ARDS patients, interleukin (IL)-1 and IL-6 receptor antagonists (IL-1Ra and IL-6Ra, kineret and tocilizumab, respectively) have shown some efficacy. Moreover, we have previously developed novel peptides modulating IL-1R and IL-6R activity (rytvela and HSJ633, respectively) while preserving immune vigilance and cytoprotective pathways. We aimed to assess the efficacy of these novel IL-1Ra and IL-6Ra, compared to commercially available drugs (kineret, tocilizumab) during the exudative phase (day 7) of bleomycin-induced acute lung injury (ALI) in mice. Our results first showed that none of the IL-1Ra and IL-6Ra compounds attenuated bleomycin-induced weight loss and venousP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ increase. Histological analyses and lung water content measurements also showed that these drugs did not improve lung injury scores or pulmonary oedema, after the bleomycin challenge. Finally, IL-1Ra and IL-6Ra failed to alleviate the inflammatory status of the mice, as indicated by cytokine levels and alveolar neutrophil infiltration. Altogether, these results indicate a lack of beneficial effects of IL-1R and IL-6R antagonists on key parameters of ALI in the bleomycin mouse model.
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MESH Headings
- Animals
- Male
- Mice
- Acute Lung Injury/drug therapy
- Acute Lung Injury/metabolism
- Antibodies, Monoclonal, Humanized/pharmacology
- Antibodies, Monoclonal, Humanized/therapeutic use
- Bleomycin
- Disease Models, Animal
- Lung/metabolism
- Lung/drug effects
- Mice, Inbred C57BL
- Receptors, Interleukin-6/antagonists & inhibitors
- Receptors, Interleukin-6/metabolism
- Receptors, Interleukin-1/antagonists & inhibitors
- Receptors, Interleukin-1/metabolism
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Affiliation(s)
- Émilie Meunier
- Centre de Recherche du Centre hospitalier de l'Université de Montréal (CRCHUM)MontréalQuébecCanada
- Département de MédecineUniversité de MontréalMontréalQuébecCanada
| | - Mélissa Aubin vega
- Centre de Recherche du Centre hospitalier de l'Université de Montréal (CRCHUM)MontréalQuébecCanada
- Département de MédecineUniversité de MontréalMontréalQuébecCanada
| | - Damien Adam
- Centre de Recherche du Centre hospitalier de l'Université de Montréal (CRCHUM)MontréalQuébecCanada
- Département de MédecineUniversité de MontréalMontréalQuébecCanada
| | - Anik Privé
- Centre de Recherche du Centre hospitalier de l'Université de Montréal (CRCHUM)MontréalQuébecCanada
| | | | - Isabelle Lahaie
- Centre de recherche du Centre hospitalier Universitaire Sainte‐JustineMontréalQuébecCanada
| | - Christiane Quiniou
- Centre de recherche du Centre hospitalier Universitaire Sainte‐JustineMontréalQuébecCanada
| | - Sylvain Chemtob
- Centre de recherche du Centre hospitalier Universitaire Sainte‐JustineMontréalQuébecCanada
- Département de pédiatrieUniversité de MontréalMontréalQuébecCanada
| | - Emmanuelle Brochiero
- Centre de Recherche du Centre hospitalier de l'Université de Montréal (CRCHUM)MontréalQuébecCanada
- Département de MédecineUniversité de MontréalMontréalQuébecCanada
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3
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Aubin Vega M, Girault A, Meunier É, Chebli J, Privé A, Robichaud A, Adam D, Brochiero E. Function of KvLQT1 potassium channels in a mouse model of bleomycin-induced acute lung injury. Front Physiol 2024; 15:1345488. [PMID: 38444763 PMCID: PMC10912346 DOI: 10.3389/fphys.2024.1345488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Accepted: 01/30/2024] [Indexed: 03/07/2024] Open
Abstract
Acute respiratory distress syndrome (ARDS) is characterized by an exacerbated inflammatory response, severe damage to the alveolar-capillary barrier and a secondary infiltration of protein-rich fluid into the airspaces, ultimately leading to respiratory failure. Resolution of ARDS depends on the ability of the alveolar epithelium to reabsorb lung fluid through active transepithelial ion transport, to control the inflammatory response, and to restore a cohesive and functional epithelium through effective repair processes. Interestingly, several lines of evidence have demonstrated the important role of potassium (K+) channels in the regulation of epithelial repair processes. Furthermore, these channels have previously been shown to be involved in sodium/fluid absorption across alveolar epithelial cells, and we have recently demonstrated the contribution of KvLQT1 channels to the resolution of thiourea-induced pulmonary edema in vivo. The aim of our study was to investigate the role of the KCNQ1 pore-forming subunit of KvLQT1 channels in the outcome of ARDS parameters in a model of acute lung injury (ALI). We used a molecular approach with KvLQT1-KO mice challenged with bleomycin, a well-established ALI model that mimics the key features of the exudative phase of ARDS on day 7. Our data showed that KvLQT1 deletion exacerbated the negative outcome of bleomycin on lung function (resistance, elastance and compliance). An alteration in the profile of infiltrating immune cells was also observed in KvLQT1-KO mice while histological analysis showed less interstitial and/or alveolar inflammatory response induced by bleomycin in KvLQT1-KO mice. Finally, a reduced repair rate of KvLQT1-KO alveolar cells after injury was observed. This work highlights the complex contribution of KvLQT1 in the development and resolution of ARDS parameters in a model of ALI.
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Affiliation(s)
- Mélissa Aubin Vega
- Centre de recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Montréal, QC, Canada
- Département de Médecine, Université de Montréal, Montréal, QC, Canada
| | - Alban Girault
- Centre de recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Montréal, QC, Canada
- Département de Médecine, Université de Montréal, Montréal, QC, Canada
- Laboratoire de Physiologie Cellulaire et Moléculaire (LPCM UR UPJV 4667), Amiens, France
| | - Émilie Meunier
- Centre de recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Montréal, QC, Canada
- Département de Médecine, Université de Montréal, Montréal, QC, Canada
| | - Jasmine Chebli
- Centre de recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Montréal, QC, Canada
- Département de Médecine, Université de Montréal, Montréal, QC, Canada
| | - Anik Privé
- Centre de recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Montréal, QC, Canada
| | | | - Damien Adam
- Centre de recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Montréal, QC, Canada
- Département de Médecine, Université de Montréal, Montréal, QC, Canada
| | - Emmanuelle Brochiero
- Centre de recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Montréal, QC, Canada
- Département de Médecine, Université de Montréal, Montréal, QC, Canada
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4
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Harvey BJ. Molecular mechanisms of dexamethasone actions in COVID-19: Ion channels and airway surface liquid dynamics. Steroids 2024; 202:109348. [PMID: 38049079 DOI: 10.1016/j.steroids.2023.109348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 11/23/2023] [Accepted: 11/28/2023] [Indexed: 12/06/2023]
Abstract
The COVID-19 pandemic has been a global health crisis of unprecedented magnitude. In the battle against the SARS-CoV-2 coronavirus, dexamethasone, a widely used corticosteroid with potent anti-inflammatory properties, has emerged as a promising therapy in the fight against severe COVID-19. Dexamethasone is a synthetic glucocorticoid that exerts its therapeutic effects by suppressing the immune system and reducing inflammation. In the context of COVID-19, the severe form of the disease is often characterized by a hyperactive immune response, known as a cytokine storm. Dexamethasone anti-inflammatory properties make it a potent tool in modulating this exaggerated immune response. Lung inflammation may lead to excessive fluid accumulation in the airways which can reduce gas exchange and mucociliary clearance. Pulmonary oedema and flooding of the airways are hallmarks of severe COVID-19 lung disease. The volume of airway surface liquid is determined by a delicate balance of salt and water secretion and absorption across the airway epithelium. In addition to its anti-inflammatory actions, dexamethasone modulates the activity of ion channels which regulate electrolyte and water transport across the airway epithelium. The observations of dexamethasone activation of sodium ion absorption via ENaC Na+ channels and inhibition of chloride ion secretion via CFTR Cl- channels to decrease airway surface liquid volume indicate a novel therapeutic action of the glucocorticoid to reverse airway flooding. This brief review delves into the early non-genomic and late genomic signaling mechanisms of dexamethasone regulation of ion channels and airway surface liquid dynamics, shedding light on the molecular mechanisms underpinning the action of the glucocorticoid in managing COVID-19.
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Affiliation(s)
- Brian J Harvey
- Faculty of Medicine, Royal College of Surgeons in Ireland, RCSI University of Medicine and Health Sciences, Dublin 2, Ireland; Centro de Estudios Cientificos, Valdivia, Chile.
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5
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Aubin Vega M, Girault A, Adam D, Chebli J, Privé A, Maillé É, Robichaud A, Brochiero E. Impact of KvLQT1 potassium channel modulation on alveolar fluid homeostasis in an animal model of thiourea-induced lung edema. Front Physiol 2023; 13:1069466. [PMID: 36699692 PMCID: PMC9868633 DOI: 10.3389/fphys.2022.1069466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 12/19/2022] [Indexed: 01/11/2023] Open
Abstract
Alveolar ion and fluid absorption is essential for lung homeostasis in healthy conditions as well as for the resorption of lung edema, a key feature of acute respiratory distress syndrome. Liquid absorption is driven by active transepithelial sodium transport, through apical ENaC Na+ channels and basolateral Na+/K+-ATPase. Our previous work unveiled that KvLQT1 K+ channels also participate in the control of Na+/liquid absorption in alveolar epithelial cells. Our aim was to further investigate the function of KvLQT1 channels and their interplay with other channels/transporters involved in ion/liquid transport in vivo using adult wild-type (WT) and KvLQT1 knock-out (KO) mice under physiological conditions and after thiourea-induced lung edema. A slight but significant increase in water lung content (WLC) was observed in naïve KvLQT1-KO mice, relative to WT littermates, whereas lung function was generally preserved and histological structure unaltered. Following thiourea-induced lung edema, KvLQT1-KO did not worsen WLC or lung function. Similarly, lung edema was not aggravated by the administration of a KvLQT1 inhibitor (chromanol). However, KvLQT1 activation (R-L3) significantly reduced WLC in thiourea-challenged WT mice. The benefits of R-L3 were prevented in KO or chromanol-treated WT mice. Furthermore, R-L3 treatment had no effect on thiourea-induced endothelial barrier alteration but restored or enhanced the levels of epithelial alveolar AQP5, Na+/K+-ATPase, and ENaC expressions. Altogether, the results indicate the benefits of KvLQT1 activation in the resolution of lung edema, probably through the observed up-regulation of epithelial alveolar channels/transporters involved in ion/water transport.
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Affiliation(s)
- Mélissa Aubin Vega
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montréal, QC, Canada,Département de Médecine, Université de Montréal, Montréal, QC, Canada
| | - Alban Girault
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montréal, QC, Canada,Département de Médecine, Université de Montréal, Montréal, QC, Canada,Laboratoire de Physiologie Cellulaire et Moléculaire (LPCM), Amiens, France
| | - Damien Adam
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montréal, QC, Canada,Département de Médecine, Université de Montréal, Montréal, QC, Canada
| | - Jasmine Chebli
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montréal, QC, Canada,Département de Médecine, Université de Montréal, Montréal, QC, Canada
| | - Anik Privé
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montréal, QC, Canada
| | - Émilie Maillé
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montréal, QC, Canada
| | | | - Emmanuelle Brochiero
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montréal, QC, Canada,Département de Médecine, Université de Montréal, Montréal, QC, Canada,*Correspondence: Emmanuelle Brochiero,
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6
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Wang Z, Bian W, Yan Y, Zhang DM. Functional Regulation of KATP Channels and Mutant Insight Into Clinical Therapeutic Strategies in Cardiovascular Diseases. Front Pharmacol 2022; 13:868401. [PMID: 35837280 PMCID: PMC9274113 DOI: 10.3389/fphar.2022.868401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 06/03/2022] [Indexed: 11/13/2022] Open
Abstract
ATP-sensitive potassium channels (KATP channels) play pivotal roles in excitable cells and link cellular metabolism with membrane excitability. The action potential converts electricity into dynamics by ion channel-mediated ion exchange to generate systole, involved in every heartbeat. Activation of the KATP channel repolarizes the membrane potential and decreases early afterdepolarization (EAD)-mediated arrhythmias. KATP channels in cardiomyocytes have less function under physiological conditions but they open during severe and prolonged anoxia due to a reduced ATP/ADP ratio, lessening cellular excitability and thus preventing action potential generation and cell contraction. Small active molecules activate and enhance the opening of the KATP channel, which induces the repolarization of the membrane and decreases the occurrence of malignant arrhythmia. Accumulated evidence indicates that mutation of KATP channels deteriorates the regulatory roles in mutation-related diseases. However, patients with mutations in KATP channels still have no efficient treatment. Hence, in this study, we describe the role of KATP channels and subunits in angiocardiopathy, summarize the mutations of the KATP channels and the functional regulation of small active molecules in KATP channels, elucidate the potential mechanisms of mutant KATP channels and provide insight into clinical therapeutic strategies.
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Affiliation(s)
- Zhicheng Wang
- Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Weikang Bian
- Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Yufeng Yan
- Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Dai-Min Zhang
- Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
- Department of Cardiology, Sir Run Run Hospital, Nanjing Medical University, Nanjing, China
- *Correspondence: Dai-Min Zhang,
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7
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Mettelman RC, Allen EK, Thomas PG. Mucosal immune responses to infection and vaccination in the respiratory tract. Immunity 2022; 55:749-780. [PMID: 35545027 PMCID: PMC9087965 DOI: 10.1016/j.immuni.2022.04.013] [Citation(s) in RCA: 83] [Impact Index Per Article: 41.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 04/12/2022] [Accepted: 04/15/2022] [Indexed: 01/25/2023]
Abstract
The lungs are constantly exposed to inhaled debris, allergens, pollutants, commensal or pathogenic microorganisms, and respiratory viruses. As a result, innate and adaptive immune responses in the respiratory tract are tightly regulated and are in continual flux between states of enhanced pathogen clearance, immune-modulation, and tissue repair. New single-cell-sequencing techniques are expanding our knowledge of airway cellular complexity and the nuanced connections between structural and immune cell compartments. Understanding these varied interactions is critical in treatment of human pulmonary disease and infections and in next-generation vaccine design. Here, we review the innate and adaptive immune responses in the lung and airways following infection and vaccination, with particular focus on influenza virus and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The ongoing SARS-CoV-2 pandemic has put pulmonary research firmly into the global spotlight, challenging previously held notions of respiratory immunity and helping identify new populations at high risk for respiratory distress.
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Affiliation(s)
- Robert C Mettelman
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - E Kaitlynn Allen
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Paul G Thomas
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
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8
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Cui X, Chen W, Zhou H, Gong Y, Zhu B, Lv X, Guo H, Duan J, Zhou J, Marcon E, Ma H. Pulmonary Edema in COVID-19 Patients: Mechanisms and Treatment Potential. Front Pharmacol 2021; 12:664349. [PMID: 34163357 PMCID: PMC8215379 DOI: 10.3389/fphar.2021.664349] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 05/25/2021] [Indexed: 12/19/2022] Open
Abstract
COVID-19 mortality is primarily driven by abnormal alveolar fluid metabolism of the lung, leading to fluid accumulation in the alveolar airspace. This condition is generally referred to as pulmonary edema and is a direct consequence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. There are multiple potential mechanisms leading to pulmonary edema in severe Coronavirus Disease (COVID-19) patients and understanding of those mechanisms may enable proper management of this condition. Here, we provide a perspective on abnormal lung humoral metabolism of pulmonary edema in COVID-19 patients, review the mechanisms by which pulmonary edema may be induced in COVID-19 patients, and propose putative drug targets that may be of use in treating COVID-19. Among the currently pursued therapeutic strategies against COVID-19, little attention has been paid to abnormal lung humoral metabolism. Perplexingly, successful balance of lung humoral metabolism may lead to the reduction of the number of COVID-19 death limiting the possibility of healthcare services with insufficient capacity to provide ventilator-assisted respiration.
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Affiliation(s)
- Xinyu Cui
- Jiangsu Collaborative Innovation Center of Chinese Medicinal Resources Industrialization, and Jiangsu Key Laboratory for High Technology Research of TCM Formulae, College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, China
| | - Wuyue Chen
- Jiangsu Collaborative Innovation Center of Chinese Medicinal Resources Industrialization, and Jiangsu Key Laboratory for High Technology Research of TCM Formulae, College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, China
| | - Haoyan Zhou
- Jiangsu Collaborative Innovation Center of Chinese Medicinal Resources Industrialization, and Jiangsu Key Laboratory for High Technology Research of TCM Formulae, College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, China
| | - Yuan Gong
- Jiangsu Collaborative Innovation Center of Chinese Medicinal Resources Industrialization, and Jiangsu Key Laboratory for High Technology Research of TCM Formulae, College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, China
| | - Bowen Zhu
- Jiangsu Collaborative Innovation Center of Chinese Medicinal Resources Industrialization, and Jiangsu Key Laboratory for High Technology Research of TCM Formulae, College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, China
| | - Xiang Lv
- Jiangsu Collaborative Innovation Center of Chinese Medicinal Resources Industrialization, and Jiangsu Key Laboratory for High Technology Research of TCM Formulae, College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, China
| | - Hongbo Guo
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, Canada
| | - Jinao Duan
- Jiangsu Collaborative Innovation Center of Chinese Medicinal Resources Industrialization, and Jiangsu Key Laboratory for High Technology Research of TCM Formulae, College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, China
| | - Jing Zhou
- Jiangsu Collaborative Innovation Center of Chinese Medicinal Resources Industrialization, and Jiangsu Key Laboratory for High Technology Research of TCM Formulae, College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, China
| | - Edyta Marcon
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, Canada
| | - Hongyue Ma
- Jiangsu Collaborative Innovation Center of Chinese Medicinal Resources Industrialization, and Jiangsu Key Laboratory for High Technology Research of TCM Formulae, College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, China
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9
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Aubin Vega M, Chupin C, Pascariu M, Privé A, Dagenais A, Berthiaume Y, Brochiero E. Dexamethasone fails to improve bleomycin-induced acute lung injury in mice. Physiol Rep 2020; 7:e14253. [PMID: 31724341 PMCID: PMC6854384 DOI: 10.14814/phy2.14253] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 09/05/2019] [Accepted: 09/08/2019] [Indexed: 02/07/2023] Open
Abstract
Acute respiratory distress syndrome (ARDS) features an exudative phase characterized by alveolar damage, lung edema and exacerbated inflammatory response. Given their anti‐inflammatory properties, the potential therapeutic effect of corticosteroids has been evaluated in ARDS clinical trials and experimental models of ALI. These studies produced contradictory results. Therefore, our aim was to investigate the effects of dexamethasone in an animal model of bleomycin‐induced acute lung injury and then to determine if the lack of response could be related to an impairment in repair ability of alveolar epithelial cells after injury. NMRI mice were challenged with bleomycin and then treated daily with dexamethasone or saline. Bronchoalveolar lavages (BAL) and lungs were collected for assessment of the inflammatory response and wet/dry ratio (lung edema) and for histological analyses. The effect of bleomycin and dexamethasone on wound repair was also evaluated in vitro on primary alveolar epithelial cell (ATII) cultures. Our data first showed that dexamethasone treatment did not reduce the weight loss or mortality rates induced by bleomycin. Although the TNF‐α level in BAL of bleomycin‐treated mice was reduced by dexamethasone, the neutrophil infiltration remained unchanged. Dexamethasone also failed to reduce lung edema and damage scores. Finally, bleomycin elicited a time‐ and dose‐dependent reduction in repair rates of ATII cell cultures. This inhibitory effect was further enhanced by dexamethasone, which also affected the expression of β3‐ and β6‐integrins, key proteins of alveolar repair. Altogether, our data indicate that the inability of dexamethasone to improve the resolution of ALI might be due to his deleterious effect on the alveolar epithelium repair.
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Affiliation(s)
- Mélissa Aubin Vega
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Montréal, Québec, Canada.,Département de Médecine, Université de Montréal, Montréal, Québec, Canada
| | - Cécile Chupin
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Montréal, Québec, Canada.,Département de Médecine, Université de Montréal, Montréal, Québec, Canada
| | - Mihai Pascariu
- Département de Médecine, Université de Montréal, Montréal, Québec, Canada.,Institut de Recherches Cliniques de Montréal (IRCM), Montréal, Québec, Canada
| | - Anik Privé
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Montréal, Québec, Canada
| | - André Dagenais
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, Québec, Canada
| | - Yves Berthiaume
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Montréal, Québec, Canada.,Département de Médecine, Université de Montréal, Montréal, Québec, Canada.,Institut de Recherches Cliniques de Montréal (IRCM), Montréal, Québec, Canada
| | - Emmanuelle Brochiero
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Montréal, Québec, Canada.,Département de Médecine, Université de Montréal, Montréal, Québec, Canada
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10
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Beswick E, Amich J, Gago S. Factoring in the Complexity of the Cystic Fibrosis Lung to Understand Aspergillus fumigatus and Pseudomonas aeruginosa Interactions. Pathogens 2020; 9:pathogens9080639. [PMID: 32781694 PMCID: PMC7460534 DOI: 10.3390/pathogens9080639] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 07/25/2020] [Accepted: 08/04/2020] [Indexed: 02/07/2023] Open
Abstract
Pseudomonas aeruginosa has long been established as the most prevalent respiratory pathogen in Cystic Fibrosis (CF) patients, with opportunistic infection causing profound morbidity and mortality. Recently, Aspergillus fumigatus has also been recognised as a key contributor to CF lung deterioration, being consistently associated with decreased lung function and worsened prognosis in these patients. As clinical evidence for the common occurrence of combined infection with these two pathogens increases, research into the mechanism and consequences of their interaction is becoming more relevant. Clinical evidence suggests a synergistic effect of combined infection, which translates into a poorer prognosis for the patients. In vitro results from the laboratory have identified a variety of possible synergistic and antagonistic interactions between A. fumigatus and P. aeruginosa. Here, we present a comprehensive overview of the complex environment of the CF lung and discuss how it needs to be considered to determine the exact molecular interactions that A. fumigatus and P. aeruginosa undergo during combined infection and their effects on the host.
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Affiliation(s)
- Emily Beswick
- Manchester Fungal Infection Group, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, Core Technology Facility, Grafton Street, Manchester M13 9NT, UK
- Academic Unit of Medical Education, Medical School, University of Sheffield, Beech Hill Road, Broomhall, Sheffield S10 2TG, UK;
| | - Jorge Amich
- Manchester Fungal Infection Group, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, Core Technology Facility, Grafton Street, Manchester M13 9NT, UK
- Correspondence: (J.A.); (S.G.)
| | - Sara Gago
- Manchester Fungal Infection Group, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, Core Technology Facility, Grafton Street, Manchester M13 9NT, UK
- Correspondence: (J.A.); (S.G.)
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11
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Bartoszewski R, Matalon S, Collawn JF. Ion channels of the lung and their role in disease pathogenesis. Am J Physiol Lung Cell Mol Physiol 2017; 313:L859-L872. [PMID: 29025712 PMCID: PMC5792182 DOI: 10.1152/ajplung.00285.2017] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 10/03/2017] [Accepted: 10/03/2017] [Indexed: 12/16/2022] Open
Abstract
Maintenance of normal epithelial ion and water transport in the lungs includes providing a thin layer of surface liquid that coats the conducting airways. This airway surface liquid is critical for normal lung function in a number of ways but, perhaps most importantly, is required for normal mucociliary clearance and bacterial removal. Preservation of the appropriate level of hydration, pH, and viscosity for the airway surface liquid requires the proper regulation and function of a battery of different types of ion channels and transporters. Here we discuss how alterations in ion channel/transporter function often lead to lung pathologies.
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Affiliation(s)
- Rafal Bartoszewski
- Department of Biology and Pharmaceutical Botany, Medical University of Gdansk, Gdansk, Poland
| | - Sadis Matalon
- Department of Anesthesiology and Perioperative Medicine, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
- Department of Cell, Developmental, and Integrative Biology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
- Pulmonary Injury and Repair Center, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama; and
- Gregory Fleming James Cystic Fibrosis Center, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
| | - James F Collawn
- Department of Cell, Developmental, and Integrative Biology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama;
- Pulmonary Injury and Repair Center, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama; and
- Gregory Fleming James Cystic Fibrosis Center, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
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12
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Cystic fibrosis lung environment and Pseudomonas aeruginosa infection. BMC Pulm Med 2016; 16:174. [PMID: 27919253 PMCID: PMC5139081 DOI: 10.1186/s12890-016-0339-5] [Citation(s) in RCA: 229] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 11/24/2016] [Indexed: 12/20/2022] Open
Abstract
Background The airways of patients with cystic fibrosis (CF) are highly complex, subject to various environmental conditions as well as a distinct microbiota. Pseudomonas aeruginosa is recognized as one of the most important pulmonary pathogens and the predominant cause of morbidity and mortality in CF. A multifarious interplay between the host, pathogens, microbiota, and the environment shapes the course of the disease. There have been several excellent reviews detailing CF pathology, Pseudomonas and the role of environment in CF but only a few reviews connect these entities with regards to influence on the overall course of the disease. A holistic understanding of contributing factors is pertinent to inform new research and therapeutics. Discussion In this article, we discuss the deterministic alterations in lung physiology as a result of CF. We also revisit the impact of those changes on the microbiota, with special emphasis on P. aeruginosa and the influence of other non-genetic factors on CF. Substantial past and current research on various genetic and non-genetic aspects of cystic fibrosis has been reviewed to assess the effect of different factors on CF pulmonary infection. A thorough review of contributing factors in CF and the alterations in lung physiology indicate that CF lung infection is multi-factorial with no isolated cause that should be solely targeted to control disease progression. A combinatorial approach may be required to ensure better disease outcomes. Conclusion CF lung infection is a complex disease and requires a broad multidisciplinary approach to improve CF disease outcomes. A holistic understanding of the underlying mechanisms and non-genetic contributing factors in CF is central to development of new and targeted therapeutic strategies.
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Chabot A, Hertig V, Boscher E, Nguyen QT, Boivin B, Chebli J, Bissonnette E, Villeneuve L, Brochiero E, Dupuis J, Calderone A. Endothelial and Epithelial Cell Transition to a Mesenchymal Phenotype Was Delineated by Nestin Expression. J Cell Physiol 2015; 231:1601-10. [DOI: 10.1002/jcp.25257] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 11/16/2015] [Indexed: 12/21/2022]
Affiliation(s)
- Andréanne Chabot
- Montreal Heart Institute; Université de Montréal; Montréal Québec Canada
- Département de Physiologie Moléculaire et Intégrative; Université de Montréal; Montréal Quebéc Canada
| | - Vanessa Hertig
- Montreal Heart Institute; Université de Montréal; Montréal Québec Canada
- Département de Physiologie Moléculaire et Intégrative; Université de Montréal; Montréal Quebéc Canada
| | - Elena Boscher
- Montreal Heart Institute; Université de Montréal; Montréal Québec Canada
| | - Quang Trinh Nguyen
- Montreal Heart Institute; Université de Montréal; Montréal Québec Canada
| | - Benoît Boivin
- Montreal Heart Institute; Université de Montréal; Montréal Québec Canada
- Département de Biochimie et; Montréal Québec Canada
- Médecine; Université de Montréal; Montréal Québec Canada
| | | | - Elyse Bissonnette
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec; Département de Médicine; Université Laval; Québec Canada
| | - Louis Villeneuve
- Montreal Heart Institute; Université de Montréal; Montréal Québec Canada
| | | | - Jocelyn Dupuis
- Montreal Heart Institute; Université de Montréal; Montréal Québec Canada
- Médecine; Université de Montréal; Montréal Québec Canada
| | - Angelino Calderone
- Montreal Heart Institute; Université de Montréal; Montréal Québec Canada
- Département de Physiologie Moléculaire et Intégrative; Université de Montréal; Montréal Quebéc Canada
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14
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Girault A, Chebli J, Privé A, Trinh NTN, Maillé E, Grygorczyk R, Brochiero E. Complementary roles of KCa3.1 channels and β1-integrin during alveolar epithelial repair. Respir Res 2015; 16:100. [PMID: 26335442 PMCID: PMC4558634 DOI: 10.1186/s12931-015-0263-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 08/21/2015] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Extensive alveolar epithelial injury and remodelling is a common feature of acute lung injury and acute respiratory distress syndrome (ARDS) and it has been established that epithelial regeneration, and secondary lung oedema resorption, is crucial for ARDS resolution. Much evidence indicates that K(+) channels are regulating epithelial repair processes; however, involvement of the KCa3.1 channels in alveolar repair has never been investigated before. RESULTS Wound-healing assays demonstrated that the repair rates were increased in primary rat alveolar cell monolayers grown on a fibronectin matrix compared to non-coated supports, whereas an anti-β1-integrin antibody reduced it. KCa3.1 inhibition/silencing impaired the fibronectin-stimulated wound-healing rates, as well as cell migration and proliferation, but had no effect in the absence of coating. We then evaluated a putative relationship between KCa3.1 channel and the migratory machinery protein β1-integrin, which is activated by fibronectin. Co-immunoprecipitation and immunofluorescence experiments indicated a link between the two proteins and revealed their cellular co-distribution. In addition, we demonstrated that KCa3.1 channel and β1-integrin membrane expressions were increased on a fibronectin matrix. We also showed increased intracellular calcium concentrations as well as enhanced expression of TRPC4, a voltage-independent calcium channel belonging to the large TRP channel family, on a fibronectin matrix. Finally, wound-healing assays showed additive effects of KCa3.1 and TRPC4 inhibitors on alveolar epithelial repair. CONCLUSION Taken together, our data demonstrate for the first time complementary roles of KCa3.1 and TRPC4 channels with extracellular matrix and β1-integrin in the regulation of alveolar repair processes.
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Affiliation(s)
- Alban Girault
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Tour Viger, 900 rue Saint-Denis, Montréal, Québec, H2X0A9, Canada. .,Département de médecine, Université de Montréal, CP6128, Succursale Centre-ville, Montréal, Québec, H3C3J7, Canada.
| | - Jasmine Chebli
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Tour Viger, 900 rue Saint-Denis, Montréal, Québec, H2X0A9, Canada. .,Département de médecine, Université de Montréal, CP6128, Succursale Centre-ville, Montréal, Québec, H3C3J7, Canada.
| | - Anik Privé
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Tour Viger, 900 rue Saint-Denis, Montréal, Québec, H2X0A9, Canada.
| | - Nguyen Thu Ngan Trinh
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Tour Viger, 900 rue Saint-Denis, Montréal, Québec, H2X0A9, Canada. .,Département de médecine, Université de Montréal, CP6128, Succursale Centre-ville, Montréal, Québec, H3C3J7, Canada.
| | - Emilie Maillé
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Tour Viger, 900 rue Saint-Denis, Montréal, Québec, H2X0A9, Canada.
| | - Ryszard Grygorczyk
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Tour Viger, 900 rue Saint-Denis, Montréal, Québec, H2X0A9, Canada. .,Département de médecine, Université de Montréal, CP6128, Succursale Centre-ville, Montréal, Québec, H3C3J7, Canada.
| | - Emmanuelle Brochiero
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Tour Viger, 900 rue Saint-Denis, Montréal, Québec, H2X0A9, Canada. .,Département de médecine, Université de Montréal, CP6128, Succursale Centre-ville, Montréal, Québec, H3C3J7, Canada.
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Lin MT, Jian MY, Taylor MS, Cioffi DL, Yap FC, Liedtke W, Townsley MI. Functional coupling of TRPV4, IK, and SK channels contributes to Ca(2+)-dependent endothelial injury in rodent lung. Pulm Circ 2015; 5:279-90. [PMID: 26064452 DOI: 10.1086/680166] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 09/15/2014] [Indexed: 02/05/2023] Open
Abstract
Our previous work has shown that the increased lung endothelial permeability response to 14,15-epoxyeicosatrienoic acid (14,15-EET) in rat lung requires Ca(2+) entry via vanilloid type-4 transient receptor potential (TRPV4) channels. Recent studies suggest that activation of TRPV4 channels in systemic vascular endothelium prolongs agonist-induced hyperpolarization and amplifies Ca(2+) entry by activating Ca(2+)-activated K(+) (KCa) channels, resulting in vessel relaxation. Activation of endothelial KCa channels thus has potential to increase the electrochemical driving force for Ca(2+) influx via TRPV4 channels and to amplify permeability responses to TRPV4 activation in lung. To examine this hypothesis, we used Western blot analysis, electrophysiological recordings, and isolated-lung permeability measurements to document expression of TRPV4 and KCa channels and the potential for functional coupling. The results show that rat pulmonary microvascular endothelial cells express TRPV4 and 3 KCa channels of different conductances: large (BK), intermediate (IK), and small (SK3). However, TRPV4 channel activity modulates the IK and SK3, but not the BK, channel current density. Furthermore, the TRPV4-mediated permeability response to 14,15-EET in mouse lung is significantly attenuated by pharmacologic blockade of IK and SK3, but not BK, channels. Collectively, this functional coupling suggests that endothelial TRPV4 channels in rodent lung likely form signaling microdomains with IK and SK3 channels and that the integrated response dictates the extent of lung endothelial injury caused by 14,15-EET.
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Affiliation(s)
- Mike T Lin
- Department of Physiology and Cell Biology, University of South Alabama, Mobile, Alabama, USA ; These authors contributed equally to this work
| | - Ming-Yuan Jian
- Department of Physiology and Cell Biology, University of South Alabama, Mobile, Alabama, USA ; Center for Lung Biology, University of South Alabama, Mobile, Alabama, USA ; Present address: Department of Anesthesiology, University of Alabama at Birmingham, Birmingham, Alabama, USA. ; These authors contributed equally to this work
| | - Mark S Taylor
- Department of Physiology and Cell Biology, University of South Alabama, Mobile, Alabama, USA
| | - Donna L Cioffi
- Center for Lung Biology, University of South Alabama, Mobile, Alabama, USA ; Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, Alabama, USA
| | - Fui C Yap
- Department of Physiology and Cell Biology, University of South Alabama, Mobile, Alabama, USA
| | - Wolfgang Liedtke
- Departments of Medicine, Neurology and Neurobiology, Duke University, Durham, North Carolina, USA
| | - Mary I Townsley
- Department of Physiology and Cell Biology, University of South Alabama, Mobile, Alabama, USA ; Center for Lung Biology, University of South Alabama, Mobile, Alabama, USA ; Department of Medicine, University of South Alabama, Mobile, Alabama, USA
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Trinh NTN, Bilodeau C, Maillé É, Ruffin M, Quintal MC, Desrosiers MY, Rousseau S, Brochiero E. Deleterious impact of Pseudomonas aeruginosa on cystic fibrosis transmembrane conductance regulator function and rescue in airway epithelial cells. Eur Respir J 2015; 45:1590-602. [PMID: 25792634 DOI: 10.1183/09031936.00076214] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Accepted: 12/28/2014] [Indexed: 11/05/2022]
Abstract
The epithelial response to bacterial airway infection, a common feature of lung diseases such as chronic obstructive pulmonary disease and cystic fibrosis, has been extensively studied. However, its impact on cystic fibrosis transmembrane conductance regulator (CFTR) channel function is not clearly defined. Our aims were, therefore, to evaluate the effect of Pseudomonas aeruginosa on CFTR function and expression in non-cystic fibrosis airway epithelial cells, and to investigate its impact on ΔF508-CFTR rescue by the VRT-325 corrector in cystic fibrosis cells. CFTR expression/maturation was evaluated by immunoblotting and its function by short-circuit current measurements. A 24-h exposure to P. aeruginosa diffusible material (PsaDM) reduced CFTR currents as well as total and membrane protein expression of the wildtype (wt) CFTR protein in CFBE-wt cells. In CFBE-ΔF508 cells, PsaDM severely reduced CFTR maturation and current rescue induced by VRT-325. We also confirmed a deleterious impact of PsaDM on wt-CFTR currents in non-cystic fibrosis primary airway cells as well as on the rescue of ΔF508-CFTR function induced by VRT-325 in primary cystic fibrosis cells. These findings show that CFTR function could be impaired in non-cystic fibrosis patients infected by P. aeruginosa. Our data also suggest that CFTR corrector efficiency may be affected by infectious components, which should be taken into account in screening assays of correctors.
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Affiliation(s)
- Nguyen Thu Ngan Trinh
- Centre de Recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC, Canada Dept de médecine, Université de Montréal, Montréal, QC, Canada Both authors contributed equally
| | - Claudia Bilodeau
- Centre de Recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC, Canada Dept de médecine, Université de Montréal, Montréal, QC, Canada Both authors contributed equally
| | - Émilie Maillé
- Centre de Recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC, Canada
| | - Manon Ruffin
- Centre de Recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC, Canada Dept de médecine, Université de Montréal, Montréal, QC, Canada
| | - Marie-Claude Quintal
- Paediatric Otolaryngology Service, Centre Hospitalier Universitaire Sainte-Justine, Montréal, QC, Canada
| | - Martin-Yvon Desrosiers
- Centre de Recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC, Canada
| | - Simon Rousseau
- Meakins-Christie Laboratories, Dept of Medicine, McGill University, Montréal, QC, Canada
| | - Emmanuelle Brochiero
- Centre de Recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC, Canada Dept de médecine, Université de Montréal, Montréal, QC, Canada
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Brune K, Frank J, Schwingshackl A, Finigan J, Sidhaye VK. Pulmonary epithelial barrier function: some new players and mechanisms. Am J Physiol Lung Cell Mol Physiol 2015; 308:L731-45. [PMID: 25637609 DOI: 10.1152/ajplung.00309.2014] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 01/27/2015] [Indexed: 12/20/2022] Open
Abstract
The pulmonary epithelium serves as a barrier to prevent access of the inspired luminal contents to the subepithelium. In addition, the epithelium dictates the initial responses of the lung to both infectious and noninfectious stimuli. One mechanism by which the epithelium does this is by coordinating transport of diffusible molecules across the epithelial barrier, both through the cell and between cells. In this review, we will discuss a few emerging paradigms of permeability changes through altered ion transport and paracellular regulation by which the epithelium gates its response to potentially detrimental luminal stimuli. This review is a summary of talks presented during a symposium in Experimental Biology geared toward novel and less recognized methods of epithelial barrier regulation. First, we will discuss mechanisms of dynamic regulation of cell-cell contacts in the context of repetitive exposure to inhaled infectious and noninfectious insults. In the second section, we will briefly discuss mechanisms of transcellular ion homeostasis specifically focused on the role of claudins and paracellular ion-channel regulation in chronic barrier dysfunction. In the next section, we will address transcellular ion transport and highlight the role of Trek-1 in epithelial responses to lung injury. In the final section, we will outline the role of epithelial growth receptor in barrier regulation in baseline, acute lung injury, and airway disease. We will then end with a summary of mechanisms of epithelial control as well as discuss emerging paradigms of the epithelium role in shifting between a structural element that maintains tight cell-cell adhesion to a cell that initiates and participates in immune responses.
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Affiliation(s)
- Kieran Brune
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland
| | - James Frank
- The Division of Pulmonary and Critical Care Medicine, University of California, San Francisco, San Francisco VA Medical Center, and NCIRE/Veterans Health Research Institute, San Francisco, California
| | - Andreas Schwingshackl
- Department of Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee
| | - James Finigan
- Division of Oncology, Cancer Center, National Jewish Health, Denver, Colorado
| | - Venkataramana K Sidhaye
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland;
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18
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Purkey MT, Li J, Mentch F, Grant SFA, Desrosiers M, Hakonarson H, Toskala E. Genetic variation in genes encoding airway epithelial potassium channels is associated with chronic rhinosinusitis in a pediatric population. PLoS One 2014; 9:e89329. [PMID: 24595210 PMCID: PMC3940609 DOI: 10.1371/journal.pone.0089329] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Accepted: 01/18/2014] [Indexed: 11/19/2022] Open
Abstract
Background Apical potassium channels regulate ion transport in airway epithelial cells and influence air surface liquid (ASL) hydration and mucociliary clearance (MCC). We sought to identify whether genetic variation within genes encoding airway potassium channels is associated with chronic rhinosinusitis (CRS). Methods Single nucleotide polymorphism (SNP) genotypes for selected potassium channels were derived from data generated on the Illumnia HumanHap550 BeadChip or Illumina Human610-Quad BeadChip for 828 unrelated individuals diagnosed with CRS and 5,083 unrelated healthy controls from the Children's Hospital of Philadelphia (CHOP). Statistical analysis was performed with set-based tests using PLINK, and corrected for multiple testing. Results Set-based case control analysis revealed the gene KCNMA1 was associated with CRS in our Caucasian subset of the cohort (598 CRS cases and 3,489 controls; p = 0.022, based on 10,000 permutations). In addition there was borderline evidence that the gene KCNQ5 (p = 0.0704) was associated with the trait in our African American subset of the cohort (230 CRS cases and 1,594 controls). In addition to the top significant SNPs rs2917454 and rs6907229, imputation analysis uncovered additional genetic variants in KCNMA1 and in KCNQ5 that were associated with CRS. Conclusions We have implicated two airway epithelial potassium channels as novel susceptibility loci in contributing to the pathogenesis of CRS.
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Affiliation(s)
- Michael T. Purkey
- Department of Otorhinolaryngology, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Jin Li
- Center for Applied Genomics, the Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Frank Mentch
- Center for Applied Genomics, the Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Struan F. A. Grant
- Division of Human Genetics, the Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Martin Desrosiers
- Department of Otolaryngology, Montreal General Hospital, McGill University, Montreal, Québec Canada
| | - Hakon Hakonarson
- Center for Applied Genomics, the Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
- Division of Human Genetics, the Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
- Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail: (HH); (ET)
| | - Elina Toskala
- Department of Otolaryngology, Temple University, Philadelphia, Pennsylvania, United States of America
- * E-mail: (HH); (ET)
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Girault A, Brochiero E. Evidence of K+ channel function in epithelial cell migration, proliferation, and repair. Am J Physiol Cell Physiol 2013; 306:C307-19. [PMID: 24196531 DOI: 10.1152/ajpcell.00226.2013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Efficient repair of epithelial tissue, which is frequently exposed to insults, is necessary to maintain its functional integrity. It is therefore necessary to better understand the biological and molecular determinants of tissue regeneration and to develop new strategies to promote epithelial repair. Interestingly, a growing body of evidence indicates that many members of the large and widely expressed family of K(+) channels are involved in regulation of cell migration and proliferation, key processes of epithelial repair. First, we briefly summarize the complex mechanisms, including cell migration, proliferation, and differentiation, engaged after epithelial injury. We then present evidence implicating K(+) channels in the regulation of these key repair processes. We also describe the mechanisms whereby K(+) channels may control epithelial repair processes. In particular, changes in membrane potential, K(+) concentration, cell volume, intracellular Ca(2+), and signaling pathways following modulation of K(+) channel activity, as well as physical interaction of K(+) channels with the cytoskeleton or integrins are presented. Finally, we discuss the challenges to efficient, specific, and safe targeting of K(+) channels for therapeutic applications to improve epithelial repair in vivo.
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Affiliation(s)
- Alban Girault
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Montreal, Quebec, Canada; and
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20
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Greenlee MM, Mitzelfelt JD, Yu L, Yue Q, Duke BJ, Harrell CS, Neigh GN, Eaton DC. Estradiol activates epithelial sodium channels in rat alveolar cells through the G protein-coupled estrogen receptor. Am J Physiol Lung Cell Mol Physiol 2013; 305:L878-89. [PMID: 24097558 DOI: 10.1152/ajplung.00008.2013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Female sex predisposes individuals to poorer outcomes during respiratory disorders like cystic fibrosis and influenza-associated pneumonia. A common link between these disorders is dysregulation of alveolar fluid clearance via disruption of epithelial sodium channel (ENaC) activity. Recent evidence suggests that female sex hormones directly regulate expression and activity of alveolar ENaC. In our study, we identified the mechanism by which estradiol (E2) or progesterone (P4) independently regulates alveolar ENaC. Using cell-attached patch clamp, we measured ENaC single-channel activity in a rat alveolar cell line (L2) in response to overnight exposure to either E2 or P4. In contrast to P4, E2 increased ENaC channel activity (NPo) through an increase in channel open probability (Po) and an increased number of patches with observable channel activity. Apical plasma membrane abundance of the ENaC α-subunit (αENaC) more than doubled in response to E2 as determined by cell surface biotinylation. αENaC membrane abundance was approximately threefold greater in lungs from female rats in proestrus, when serum E2 is greatest, compared with diestrus, when it is lowest. Our results also revealed a significant role for the G protein-coupled estrogen receptor (Gper) to mediate E2's effects on ENaC. Overall, our results demonstrate that E2 signaling through Gper selectively activates alveolar ENaC through an effect on channel gating and channel density, the latter via greater trafficking of channels to the plasma membrane. The results presented herein implicate E2-mediated regulation of alveolar sodium channels in the sex differences observed in the pathogenesis of several pulmonary diseases.
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Affiliation(s)
- Megan M Greenlee
- Dept. of Physiology, Emory Univ. School of Medicine, 615 Michael St., Ste. 655B, Atlanta, GA 30322.
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Abstract
Ion channels perform a variety of cellular functions in lung epithelia. Oxidant- and antioxidant-mediated mechanisms (that is, redox regulation) of ion channels are areas of intense research. Significant progress has been made in our understanding of redox regulation of ion channels since the last Experimental Biology report in 2003. Advancements include: 1) identification of nonphagocytic NADPH oxidases as sources of regulated reactive species (RS) production in epithelia, 2) an understanding that excessive treatment with antioxidants can result in greater oxidative stress, and 3) characterization of novel RS signaling pathways that converge upon ion channel regulation. These advancements, as discussed at the 2013 Experimental Biology Meeting in Boston, MA, impact our understanding of oxidative stress in the lung, and, in particular, illustrate that the redox state has profound effects on ion channel and cellular function.
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Dagenais A, Tessier MC, Tatur S, Brochiero E, Grygorczyk R, Berthiaume Y. Hypotonic shock modulates Na(+) current via a Cl(-) and Ca(2+)/calmodulin dependent mechanism in alveolar epithelial cells. PLoS One 2013; 8:e74565. [PMID: 24019969 PMCID: PMC3760838 DOI: 10.1371/journal.pone.0074565] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2012] [Accepted: 08/05/2013] [Indexed: 12/02/2022] Open
Abstract
Alveolar epithelial cells are involved in Na+ absorption via the epithelial Na+ channel (ENaC), an important process for maintaining an appropriate volume of liquid lining the respiratory epithelium and for lung oedema clearance. Here, we investigated how a 20% hypotonic shock modulates the ionic current in these cells. Polarized alveolar epithelial cells isolated from rat lungs were cultured on permeant filters and their electrophysiological properties recorded. A 20% bilateral hypotonic shock induced an immediate, but transient 52% rise in total transepithelial current and a 67% increase in the amiloride-sensitive current mediated by ENaC. Amiloride pre-treatment decreased the current rise after hypotonic shock, showing that ENaC current is involved in this response. Since Cl- transport is modulated by hypotonic shock, its contribution to the basal and hypotonic-induced transepithelial current was also assessed. Apical NPPB, a broad Cl- channel inhibitor and basolateral DIOA a potassium chloride co-transporter (KCC) inhibitor reduced the total and ENaC currents, showing that transcellular Cl- transport plays a major role in that process. During hypotonic shock, a basolateral Cl- influx, partly inhibited by NPPB is essential for the hypotonic-induced current rise. Hypotonic shock promoted apical ATP secretion and increased intracellular Ca2+. While apyrase, an ATP scavenger, did not inhibit the hypotonic shock current response, W7 a calmodulin antagonist completely prevented the hypotonic current rise. These results indicate that a basolateral Cl- influx as well as Ca2+/calmodulin, but not ATP, are involved in the acute transepithelial current rise elicited by hypotonic shock.
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Affiliation(s)
- André Dagenais
- Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada
- Département de Médecine, Université de Montréal, Montreal, Quebec, Canada
- * E-mail:
| | | | - Sabina Tatur
- Centre de Recherche du CHUM (CRCHUM), Centre Hospitalier de l’Université de Montréal, Montreal, Quebec, Canada
| | - Emmanuelle Brochiero
- Département de Médecine, Université de Montréal, Montreal, Quebec, Canada
- Centre de Recherche du CHUM (CRCHUM), Centre Hospitalier de l’Université de Montréal, Montreal, Quebec, Canada
| | - Ryszard Grygorczyk
- Département de Médecine, Université de Montréal, Montreal, Quebec, Canada
- Centre de Recherche du CHUM (CRCHUM), Centre Hospitalier de l’Université de Montréal, Montreal, Quebec, Canada
| | - Yves Berthiaume
- Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada
- Département de Médecine, Université de Montréal, Montreal, Quebec, Canada
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K+ channels regulate ENaC expression via changes in promoter activity and control fluid clearance in alveolar epithelial cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1818:1682-90. [PMID: 22406554 DOI: 10.1016/j.bbamem.2012.02.025] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Revised: 02/16/2012] [Accepted: 02/22/2012] [Indexed: 12/21/2022]
Abstract
Active Na+ absorption by alveolar ENaC is the main driving force of liquid clearance at birth and lung edema resorption in adulthood. We have demonstrated previously that long-term modulation of KvLQT1 and KATP K+ channel activities exerts sustained control in Na+ transport through the regulation of ENaC expression in primary alveolar type II (ATII) cells. The goal of the present study was: 1) to investigate the role of the alpha-ENaC promoter, transfected in the A549 alveolar cell line, in the regulation of ENaC expression by K+ channels, and 2) to determine the physiological impact of K+ channels and ENaC modulation on fluid clearance in ATII cells. KvLQT1 and KATP channels were first identified in A549 cells by PCR and Western blotting. We showed, for the first time, that KvLQT1 activation by R-L3 (applied for 24 h) increased alpha-ENaC expression, similarly to KATP activation by pinacidil. Conversely, pharmacological KvLQT1 and KATP inhibition or silencing with siRNAs down-regulated alpha-ENaC expression. Furthermore, K+ channel blockers significantly decreased alpha-ENaC promoter activity. Our results indicated that this decrease in promoter activity could be mediated, at least in part, by the repressor activity of ERK1/2. Conversely, KvLQT1 and KATP activation dose-dependently enhanced alpha-ENaC promoter activity. Finally, we noted a physiological impact of changes in K+ channel functions on ERK activity, alpha-, beta-, gamma-ENaC subunit expression and fluid absorption through polarized ATII cells. In summary, our results disclose that K+ channels regulate alpha-ENaC expression by controlling its promoter activity and thus affect the alveolar function of fluid clearance.
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24
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Ion transport by pulmonary epithelia. J Biomed Biotechnol 2011; 2011:174306. [PMID: 22131798 PMCID: PMC3205707 DOI: 10.1155/2011/174306] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 08/16/2011] [Indexed: 12/13/2022] Open
Abstract
The lung surface of air-breathing vertebrates is formed by a continuous epithelium that is covered by a fluid layer. In the airways, this epithelium is largely pseudostratified consisting of diverse cell types such as ciliated cells, goblet cells, and undifferentiated basal cells, whereas the alveolar epithelium consists of alveolar type I and alveolar type II cells. Regulation and maintenance of the volume and viscosity of the fluid layer covering the epithelium is one of the most important functions of the epithelial barrier that forms the outer surface area of the lungs. Therefore, the epithelial cells are equipped with a wide variety of ion transport proteins, among which Na+, Cl−, and K+ channels have been identified to play a role in the regulation of the fluid layer. Malfunctions of pulmonary epithelial ion transport processes and, thus, impairment of the liquid balance in our lungs is associated with severe diseases, such as cystic fibrosis and pulmonary oedema. Due to the important role of pulmonary epithelial ion transport processes for proper lung function, the present paper summarizes the recent findings about composition, function, and ion transport properties of the airway epithelium as well as of the alveolar epithelium.
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Mac Sweeney R, Fischer H, McAuley DF. Nasal potential difference to detect Na+ channel dysfunction in acute lung injury. Am J Physiol Lung Cell Mol Physiol 2010; 300:L305-18. [PMID: 21112943 DOI: 10.1152/ajplung.00223.2010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Pulmonary fluid clearance is regulated by the active transport of Na(+) and Cl(-) through respiratory epithelial ion channels. Ion channel dysfunction contributes to the pathogenesis of various pulmonary fluid disorders including high-altitude pulmonary edema (HAPE) and neonatal respiratory distress syndrome (RDS). Nasal potential difference (NPD) measurement allows an in vivo investigation of the functionality of these channels. This technique has been used for the diagnosis of cystic fibrosis, the archetypal respiratory ion channel disorder, for over a quarter of a century. NPD measurements in HAPE and RDS suggest constitutive and acquired dysfunction of respiratory epithelial Na(+) channels. Acute lung injury (ALI) is characterized by pulmonary edema due to alveolar epithelial-interstitial-endothelial injury. NPD measurement may enable identification of critically ill ALI patients with a susceptible phenotype of dysfunctional respiratory Na(+) channels and allow targeted therapy toward Na(+) channel function.
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Affiliation(s)
- R Mac Sweeney
- Respiratory Medicine Research Programme, Centre for Infection and Immunity, Queen’s University, Belfast, Northern Ireland
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Bove PF, Grubb BR, Okada SF, Ribeiro CMP, Rogers TD, Randell SH, O'Neal WK, Boucher RC. Human alveolar type II cells secrete and absorb liquid in response to local nucleotide signaling. J Biol Chem 2010; 285:34939-49. [PMID: 20801871 PMCID: PMC2966108 DOI: 10.1074/jbc.m110.162933] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Revised: 08/23/2010] [Indexed: 12/21/2022] Open
Abstract
A balance sheet describing the integrated homeostasis of secretion, absorption, and surface movement of liquids on pulmonary surfaces has remained elusive. It remains unclear whether the alveolus exhibits an intra-alveolar ion/liquid transport physiology or whether it secretes ions/liquid that may communicate with airway surfaces. Studies employing isolated human alveolar type II (AT2) cells were utilized to investigate this question. Human AT2 cells exhibited both epithelial Na(+) channel-mediated Na(+) absorption and cystic fibrosis transmembrane conductance regulator-mediated Cl(-) secretion, both significantly regulated by extracellular nucleotides. In addition, we observed in normal AT2 cells an absence of cystic fibrosis transmembrane conductance regulator regulation of epithelial Na(+) channel activity and an absence of expression/activity of reported calcium-activated chloride channels (TMEM16A, Bestrophin-1, ClC2, and SLC26A9), both features strikingly different from normal airway epithelial cells. Measurements of alveolar surface liquid volume revealed that normal AT2 cells: 1) achieved an extracellular nucleotide concentration-dependent steady state alveolar surface liquid height of ∼4 μm in vitro; 2) absorbed liquid when the lumen was flooded; and 3) secreted liquid when treated with UTP or forskolin or subjected to cyclic compressive stresses mimicking tidal breathing. Collectively, our studies suggest that human AT2 cells in vitro have the capacity to absorb or secrete liquid in response to local alveolar conditions.
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Affiliation(s)
- Peter F. Bove
- From the Department of Medicine, Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Barbara R. Grubb
- From the Department of Medicine, Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Seiko F. Okada
- From the Department of Medicine, Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Carla M. P. Ribeiro
- From the Department of Medicine, Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Troy D. Rogers
- From the Department of Medicine, Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Scott H. Randell
- From the Department of Medicine, Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Wanda K. O'Neal
- From the Department of Medicine, Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Richard C. Boucher
- From the Department of Medicine, Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
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Rubenstein RC, Lockwood SR, Lide E, Bauer R, Suaud L, Grumbach Y. Regulation of endogenous ENaC functional expression by CFTR and ΔF508-CFTR in airway epithelial cells. Am J Physiol Lung Cell Mol Physiol 2010; 300:L88-L101. [PMID: 20935229 DOI: 10.1152/ajplung.00142.2010] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The functional expression of the epithelial sodium channel (ENaC) appears elevated in cystic fibrosis (CF) airway epithelia, but the mechanism by which this occurs is not clear. We tested the hypothesis that the cystic fibrosis transmembrane conductance regulator (CFTR) alters the trafficking of endogenously expressed human ENaC in the CFBE41o⁻ model of CF bronchial epithelia. Functional expression of ENaC, as defined by amiloride-inhibited short-circuit current (I(sc)) in Ussing chambers, was absent under control conditions but present in CFBE41o⁻ parental and ΔF508-CFTR-overexpressing cells after treatment with 1 μM dexamethasone (Dex) for 24 h. The effect of Dex was mimicked by incubation with the glucocorticoid hydrocortisone but not with the mineralocorticoid aldosterone. Application of trypsin to the apical surface to activate uncleaved, "near-silent" ENaC caused an additional increase in amiloride-sensitive I(sc) in the Dex-treated cells and was without effect in the control cells, suggesting that Dex increased ENaC cell surface expression. In contrast, Dex treatment did not stimulate amiloride-sensitive I(sc) in CFBE41o⁻ cells that stably express wild-type (wt) CFTR. CFBE41o⁻ wt cells also had reduced expression of α- and γ-ENaC compared with parental and ΔF508-CFTR-overexpressing cells. Furthermore, application of trypsin to the apical surface of Dex-treated CFBE41o⁻ wt cells did not stimulate amiloride-sensitive I(sc), suggesting that ENaC remained absent from the surface of these cells even after Dex treatment. We also tested the effect of trafficking-corrected ΔF508-CFTR on ENaC functional expression. Incubation with 1 mM 4-phenylbutyrate synergistically increased Dex-induced ENaC functional expression in ΔF508-CFTR-overexpressing cells. These data support the hypothesis that wt CFTR can regulate the whole cell, functional, and surface expression of endogenous ENaC in airway epithelial cells and that absence of this regulation may foster ENaC hyperactivity in CF airway epithelia.
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Affiliation(s)
- Ronald C Rubenstein
- The Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine, Philadelphia, USA.
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Piro D, Rejman J, Conese M. Stem cell therapy for cystic fibrosis: current status and future prospects. Expert Rev Respir Med 2010; 2:365-80. [PMID: 20477199 DOI: 10.1586/17476348.2.3.365] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Although cystic fibrosis (CF), an autosomal recessive disease caused by mutations in the gene encoding for the CF transmembrane conductance regulator (CFTR), seems a good candidate for gene therapy, 15 years of intense investigation and a number of clinical trials have not yet produced a viable clinical gene-therapy strategy. In addition, the duration of gene expression has been shown to be limited, only lasting 1-4 weeks. Therefore, alternative approaches involve the search for, and use of, stem cell populations. Bone marrow contains different stem cell types, including hematopoietic stem cells and multipotent mesenchymal stromal cells. Numerous studies have now demonstrated the ability of hematopoietic stem cells and mesenchymal stromal cells to home to the lung and differentiate into epithelial cells of both the conducting airways and the alveolar region. However, engraftment of bone marrow-derived stem cells into the airways is a very inefficient process. Detailed knowledge of the cellular and molecular determinants governing homing to the lung and transformation of marrow cells into lung epithelial cells would benefit this process. Despite a very low level of engraftment of donor cells into the nose and gut, significant CFTR mRNA expression and a measurable level of correction of the electrophysiological defect were observed after transplantation of wild-type marrow cells into CF mice. It is uncertain whether this effect is due to the presence of CFTR-expressing epithelial cells derived from donor cells or to the immunomodulatory role of transplanted cells. Finally, initial studies on the usefulness of umbilical cord blood and embryonic stem cells in the generation of airway epithelial cells will be discussed in this review.
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Affiliation(s)
- Donatella Piro
- Department of Biomedical Sciences, University of Foggia, c/o Ospedali Riuniti, Viale L. Pinto 1, 71100 Foggia, Italy.
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Falkenberg CV, Jakobsson E. A biophysical model for integration of electrical, osmotic, and pH regulation in the human bronchial epithelium. Biophys J 2010; 98:1476-85. [PMID: 20409466 DOI: 10.1016/j.bpj.2009.11.045] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2009] [Revised: 11/11/2009] [Accepted: 11/19/2009] [Indexed: 12/14/2022] Open
Abstract
A dynamical biophysical model for the functioning of an epithelium is presented. This model integrates the electrical and osmotic behaviors of the epithelium, taking into account intracellular conditions. The specific tissue modeled is the human bronchial epithelium, which is of particular interest, as it is the location of the most common lethal symptoms of cystic fibrosis. The model is implemented in a modular form to facilitate future application of the code to other epithelial tissue by inputting different transporters, channels, and geometric parameters. The model includes pH regulation as an integral component of overall regulation of epithelial function, through the interdependence of pH, bicarbonate concentration, and current. The procedures for specification, the validation of the model, and parametric studies are presented using available experimental data of cultured human bronchial epithelium. Parametric studies are performed to elucidate a), the contribution of basolateral chloride channels to the short-circuit current functional form, and b), the role that regulation of basolateral potassium conductance plays in epithelial function.
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Affiliation(s)
- Cibele V Falkenberg
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
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30
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Han DY, Nie HG, Gu X, Nayak RC, Su XF, Fu J, Chang Y, Rao V, Ji HL. K+ channel openers restore verapamil-inhibited lung fluid resolution and transepithelial ion transport. Respir Res 2010; 11:65. [PMID: 20507598 PMCID: PMC2889873 DOI: 10.1186/1465-9921-11-65] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Accepted: 05/27/2010] [Indexed: 12/19/2022] Open
Abstract
Background Lung epithelial Na+ channels (ENaC) are regulated by cell Ca2+ signal, which may contribute to calcium antagonist-induced noncardiogenic lung edema. Although K+ channel modulators regulate ENaC activity in normal lungs, the therapeutical relevance and the underlying mechanisms have not been completely explored. We hypothesized that K+ channel openers may restore calcium channel blocker-inhibited alveolar fluid clearance (AFC) by up-regulating both apical and basolateral ion transport. Methods Verapamil-induced depression of heterologously expressed human αβγ ENaC in Xenopus oocytes, apical and basolateral ion transport in monolayers of human lung epithelial cells (H441), and in vivo alveolar fluid clearance were measured, respectively, using the two-electrode voltage clamp, Ussing chamber, and BSA protein assays. Ca2+ signal in H441 cells was analyzed using Fluo 4AM. Results The rate of in vivo AFC was reduced significantly (40.6 ± 6.3% of control, P < 0.05, n = 12) in mice intratracheally administrated verapamil. KCa3.1 (1-EBIO) and KATP (minoxidil) channel openers significantly recovered AFC. In addition to short-circuit current (Isc) in intact H441 monolayers, both apical and basolateral Isc levels were reduced by verapamil in permeabilized monolayers. Moreover, verapamil significantly altered Ca2+ signal evoked by ionomycin in H441 cells. Depletion of cytosolic Ca2+ in αβγ ENaC-expressing oocytes completely abolished verapamil-induced inhibition. Intriguingly, KV (pyrithione-Na), K Ca3.1 (1-EBIO), and KATP (minoxidil) channel openers almost completely restored the verapamil-induced decrease in Isc levels by diversely up-regulating apical and basolateral Na+ and K+ transport pathways. Conclusions Our observations demonstrate that K+ channel openers are capable of rescuing reduced vectorial Na+ transport across lung epithelial cells with impaired Ca2+ signal.
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Affiliation(s)
- Dong-Yun Han
- Department of Biochemistry, University of Texas Health Science Center at Tyler, Tyler, TX 75708, USA
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Roux J, Carles M, Koh H, Goolaerts A, Ganter MT, Chesebro BB, Howard M, Houseman BT, Finkbeiner W, Shokat KM, Paquet AC, Matthay MA, Pittet JF. Transforming growth factor beta1 inhibits cystic fibrosis transmembrane conductance regulator-dependent cAMP-stimulated alveolar epithelial fluid transport via a phosphatidylinositol 3-kinase-dependent mechanism. J Biol Chem 2009; 285:4278-90. [PMID: 19996317 DOI: 10.1074/jbc.m109.036731] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Exogenous or endogenous beta(2)-adrenergic receptor agonists enhance alveolar epithelial fluid transport via a cAMP-dependent mechanism that protects the lungs from alveolar flooding in acute lung injury. However, impaired alveolar fluid clearance is present in most of the patients with acute lung injury and is associated with increased mortality, although the mechanisms responsible for this inhibition of the alveolar epithelial fluid transport are not completely understood. Here, we found that transforming growth factor beta1 (TGF-beta1), a critical mediator of acute lung injury, inhibits beta(2)-adrenergic receptor agonist-stimulated vectorial fluid and Cl(-) transport across primary rat and human alveolar epithelial type II cell monolayers. This inhibition is due to a reduction in the cystic fibrosis transmembrane conductance regulator activity and biosynthesis mediated by a phosphatidylinositol 3-kinase (PI3K)-dependent heterologous desensitization and down-regulation of the beta(2)-adrenergic receptors. Consistent with these in vitro results, inhibition of the PI3K pathway or pretreatment with soluble chimeric TGF-beta type II receptor restored beta(2)-adrenergic receptor agonist-stimulated alveolar epithelial fluid transport in an in vivo model of acute lung injury induced by hemorrhagic shock in rats. The results demonstrate a novel role for TGF-beta1 in impairing the beta- adrenergic agonist-stimulated alveolar fluid clearance in acute lung injury, an effect that could be corrected by using PI3K inhibitors that are safe to use in humans.
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Affiliation(s)
- Jérémie Roux
- Laboratory of Surgical Research, Department of Anesthesia, University of California, San Francisco, California 94110, USA.
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Abstract
Transcripts of more than 30 different K(+) channels have been detected in the respiratory epithelium lining airways and alveoli. These channels belong to the 3 main classes of K(+) channels, i.e. i) voltage-dependent or calcium-activated, 6 transmembrane segments (TM), ii) 2-pores 4-TM and iii) inward-rectified 2-TM channels. The physiological and functional significance of this high molecular diversity of lung epithelial K(+) channels is not well understood. Surprisingly, relatively few studies are focused on K(+) channel function in lung epithelial physiology. Nevertheless, several studies have shown that KvLQT1, KCa and K(ATP) K(+) channels play a crucial role in ion and fluid transport, contributing to the control of airway and alveolar surface liquid composition and volume. K(+) channels are involved in other key functions, such as O(2) sensing or the capacity of the respiratory epithelia to repair after injury. This mini-review aims to discuss potential functions of lung K(+) channels.
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Affiliation(s)
- Olivier Bardou
- Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM), Hôtel-Dieu, 3840, St-Urbain, Montréal, Québec, H2W 1T8 Canada
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Role of the C-Terminal Part of the Extracellular Domain of the α-ENaC in Activation by Sulfonylurea Glibenclamide. J Membr Biol 2009; 230:133-41. [DOI: 10.1007/s00232-009-9193-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2009] [Accepted: 07/28/2009] [Indexed: 10/20/2022]
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Yang C, Su L, Wang Y, Liu L. UTP regulation of ion transport in alveolar epithelial cells involves distinct mechanisms. Am J Physiol Lung Cell Mol Physiol 2009; 297:L439-54. [PMID: 19542245 DOI: 10.1152/ajplung.90268.2008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
UTP is known to regulate alveolar fluid clearance. However, the relative contribution of alveolar type I cells and type II cells to this process is unknown. In this study, we investigated the effects of UTP on ion transport in type I-like cell (AEC I) and type II-like cell (AEC II) monolayers. Luminal treatment of cell monolayers with UTP increased short-circuit current (I(sc)) of AEC II but decreased I(sc) of AEC I. The Cl(-) channel blockers NPPB and DIDS inhibited the UTP-induced changes in I(sc) (DeltaIsc) in both types of cells. Amiloride, an inhibitor of epithelial Na(+) channels (ENaC), abolished the UTP-induced DeltaI(sc) in AEC I, but not in AEC II. The general blocker of K(+) channels, BaCl(2), eliminated the UTP-induced DeltaI(sc) in AEC II, but not in AEC I. The intermediate conductance (IK(Ca)) blocker, clofilium, also blocked the UTP effect in AEC II. The signal transduction pathways mediated by UTP were the same in AEC I and AEC II. Furthermore, UTP increased Cl(-) secretion in AEC II and Cl(-) absorption in AEC I. Our results suggest that UTP induces opposite changes in I(sc) in AEC I and AEC II, likely due to the reversed Cl(-) flux and different contributions of ENaC and IK(Ca). Our results further imply a new concept that type II cells contribute to UTP-induced fluid secretion and type I cells contribute to UTP-induced fluid absorption in alveoli.
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Affiliation(s)
- Chuanxiu Yang
- Lundberg-Kienlen Lung Biology and Toxicology Laboratory, Department of Physiological Sciences, Oklahoma State University, Stillwater, Oklahoma 74078, USA
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Bardou O, Trinh NTN, Brochiero E. Molecular diversity and function of K+ channels in airway and alveolar epithelial cells. Am J Physiol Lung Cell Mol Physiol 2008; 296:L145-55. [PMID: 19060226 DOI: 10.1152/ajplung.90525.2008] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Multiple K(+) channels are expressed in the respiratory epithelium lining airways and alveoli. Of the three main classes [1) voltage-dependent or Ca(2+)-activated, 6-transmembrane domains (TMD), 2) 2-pores 4-TMD, and 3) inward-rectified 2-TMD K(+) channels], almost 40 different transcripts have already been detected in the lung. The physiological and functional significance of this high molecular diversity of lung epithelial K(+) channels is intriguing. As detailed in the present review, K(+) channels are located at both the apical and basolateral membranes in the respiratory epithelium, where they mediate K(+) currents of diverse electrophysiological and regulatory properties. The main recognized function of K(+) channels is to control membrane potential and to maintain the driving force for transepithelial ion and liquid transport. In this manner, KvLQT1, KCa and K(ATP) channels, for example, contribute to the control of airway and alveolar surface liquid composition and volume. Thus, K(+) channel activation has been identified as a potential therapeutic strategy for the resolution of pathologies characterized by ion transport dysfunction. K(+) channels are also involved in other key functions in lung physiology, such as oxygen-sensing, inflammatory responses and respiratory epithelia repair after injury. The purpose of this review is to summarize and discuss what is presently known about the molecular identity of lung K(+) channels with emphasis on their role in lung epithelial physiology.
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Affiliation(s)
- Olivier Bardou
- Centre de recherche du CHUM, Hôtel-Dieu, 3840, Saint-Urbain, Montréal, Québec H2W 1T8, Canada
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Trinh NTN, Privé A, Maillé E, Noël J, Brochiero E. EGF and K+ channel activity control normal and cystic fibrosis bronchial epithelia repair. Am J Physiol Lung Cell Mol Physiol 2008; 295:L866-80. [PMID: 18757521 DOI: 10.1152/ajplung.90224.2008] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Severe lesions of airway epithelia are observed in cystic fibrosis (CF) patients. The regulatory mechanisms of cell migration and proliferation processes, involved in the repair of injured epithelia, then need to be better understood. A model of mechanical wounding of non-CF (NuLi) and CF (CuFi) bronchial monolayers was employed to study the repair mechanisms. We first observed that wound repair, under paracrine and autocrine EGF control, was slower (up to 33%) in CuFi than in NuLi. Furthermore, EGF receptor (EGFR) activation, following wounding, was lower in CuFi than in NuLi monolayers. Cell proliferation and migration assays indicated a similar rate of proliferation in both cell lines but with reduced (by 25%) CuFi cell migration. In addition, cell migration experiments performed in the presence of conditioned medium, collected from NuLi and CuFi wounded bronchial monolayers, suggested a defect in EGF/EGFR signaling in CF cells. We (49) recently demonstrated coupling between the EGF response and K(+) channel function, which is crucial for EGF-stimulated alveolar repair. In CuFi cells, lower EGF/EGFR signaling was accompanied by a 40-70% reduction in K(+) currents and KvLQT1, ATP-sensitive potassium (K(ATP)), and Ca(2+)-activated K(+) (KCa3.1) channel expression. In addition, EGF-stimulated bronchial wound healing, cell migration, and proliferation were severely decreased by K(+) channel inhibitors. Finally, acute CFTR inhibition failed to reduce wound healing, EGF secretion, and K(+) channel expression in NuLi. In summary, the delay in CuFi wound healing could be due to diminished EGFR signaling coupled with lower K(+) channel function, which play a crucial role in bronchial repair.
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Impact of mechanical stress on ion transport in native lung epithelium (Xenopus laevis): short-term activation of Na+, Cl (-) and K+ channels. Pflugers Arch 2008; 456:1109-20. [PMID: 18581136 DOI: 10.1007/s00424-008-0486-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2007] [Revised: 01/31/2008] [Accepted: 02/27/2008] [Indexed: 01/11/2023]
Abstract
Epithelia, in general, and the lung epithelium, in particular, are exposed to mechanical forces, but little is known about their impact on pulmonary ion transport. In our present study, we employed transepithelial ion transport measurements on Xenopus lung preparations using custom-built Ussing chambers. Tissues were exposed to mechanical stress by increasing the water column (5 cm) at one side of the tissues. Apical exposure to hydrostatic pressure significantly decreased the short circuit current (I (SC): 24 +/- 1%, n = 152), slightly decreased the transepithelial resistance (R (T): 7 +/- 2%, n = 152), but increased the apical membrane capacitance (C (M): 16 +/- 6%, n = 9). The pressure-induced effect was sensitive to Na+ (amiloride), Cl(-) (DIDS, NFA, NPPB) and K+ channel blockers (Ba2+), glibenclamide). Further on, it was accompanied by increased extracellular ATP levels. The results show that mechanical stress leads to an activation of Na+, Cl(-), and K+ conductances in a native pulmonary epithelium resulting in a net decrease of ion absorption. This could be of considerable interest, since an altered ion transport may contribute to pathophysiological conditions, e.g., the formation of pulmonary edema during artificial ventilation.
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Bai X, Ma J, Pan Z, Song YH, Freyberg S, Yan Y, Vykoukal D, Alt E. Electrophysiological properties of human adipose tissue-derived stem cells. Am J Physiol Cell Physiol 2007; 293:C1539-50. [PMID: 17687001 DOI: 10.1152/ajpcell.00089.2007] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Human adipose tissue-derived stem cells (hASCs) represent a potentially valuable cell source for clinical therapeutic applications. The present study was designed to investigate properties of ionic channel currents present in undifferentiated hASCs and their impact on hASCs proliferation. The functional ion channels in hASCs were analyzed by whole-cell patch-clamp recording and their mRNA expression levels detected by RT-PCR. Four types of ion channels were found to be present in hASCs: most of the hASCs (73%) showed a delayed rectifier-like K(+) current (I(KDR)); Ca(2+)-activated K(+) current (I(KCa)) was detected in examined cells; a transient outward K(+) current (I(to)) was recorded in 19% of the cells; a small percentage of cells (8%) displayed a TTX-sensitive transient inward sodium current (I(Na.TTX)). RT-PCR results confirmed the presence of ion channels at the mRNA level: Kv1.1, Kv2.1, Kv1.5, Kv7.3, Kv11.1, and hEAG1, possibly encoding I(KDR); MaxiK, KCNN3, and KCNN4 for I(KCa); Kv1.4, Kv4.1, Kv4.2, and Kv4.3 for I(to) and hNE-Na for I(Na.TTX). The I(KDR) was inhibited by tetraethyl ammonium (TEA) and 4-aminopyridine (4-AP), which significantly reduced the proliferation of hASCs in a dose-dependent manner (P < 0.05), as suggested by bromodeoxyurindine (BrdU) incorporation. Other selective potassium channel blockers, including linopiridine, iberiotoxin, clotrimazole, and apamin also significantly inhibited I(KDR). TTX completely abolished I(Na.TTX). This study demonstrates for the first time that multiple functional ion channel currents such as I(KDR), I(KCa), I(to), and I(Na.TTX) are present in undifferentiated hASCs and their potential physiological function in these cells as a basic understanding for future in vitro experiments and in vivo clinical investigations.
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Affiliation(s)
- Xiaowen Bai
- Department of Molecular Pathology, University of Texas, MD Anderson Cancer Center, Houston, Texas 77054, USA
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Trinh NTN, Privé A, Kheir L, Bourret JC, Hijazi T, Amraei MG, Noël J, Brochiero E. Involvement of KATP and KvLQT1 K+ channels in EGF-stimulated alveolar epithelial cell repair processes. Am J Physiol Lung Cell Mol Physiol 2007; 293:L870-82. [PMID: 17631610 DOI: 10.1152/ajplung.00362.2006] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Several respiratory diseases are associated with extensive damage of lung epithelia, and the regulatory mechanisms involved in their regeneration are not clearly defined. Growth factors released by epithelial cells or fibroblasts from injured lungs are important regulators of alveolar repair by stimulating cell motility, proliferation, and differentiation. In addition, K(+) channels regulate cell proliferation/migration and are coupled with growth factor signaling in several tissues. We decided to explore the hypothesis, never investigated before, that K(+) could play a prominent role in alveolar repair. We employed a model of mechanical wounding of rat alveolar type II epithelia, in primary culture, to study their response to injury. Wound healing was suppressed by one-half upon epidermal growth factor (EGF) titration with EGF-antibody (Ab) or erbB1/erbB2 tyrosine-kinase inhibition with AG-1478/AG-825. The addition of exogenous EGF slightly stimulated the alveolar wound healing and enhanced, by up to five times, alveolar cell migration measured in a Boyden-type chamber. Conditioned medium collected from injured alveolar monolayers also stimulated cell migration; this effect was abolished in the presence of EGF-Ab. The impact of K(+) channel modulators was examined in basal and EGF-stimulated conditions. Wound healing was stimulated by pinacidil, an ATP-dependent K(+) channel (K(ATP)) activator, which also increased cell migration, by twofold, in basal conditions and potentiated the stimulatory effect of EGF. K(ATP) or KvLQT1 inhibitors (glibenclamide, clofilium) reduced EGF-stimulated wound healing, cell migration, and proliferation. Finally, EGF stimulated K(ATP) and KvLQT1 currents and channel expression. In summary, stimulation of K(+) channels through autocrine activation of EGF receptors could play a crucial role in lung epithelia repair processes.
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Affiliation(s)
- Nguyen Thu Ngan Trinh
- Centre de Recherche, Centre Hospitalier de l'Université de Montréal-Hôtel-DieuMontréal, Québec, Canada H2W 1T7
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Dobbs LG, Johnson MD. Alveolar epithelial transport in the adult lung. Respir Physiol Neurobiol 2007; 159:283-300. [PMID: 17689299 DOI: 10.1016/j.resp.2007.06.011] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2007] [Revised: 05/31/2007] [Accepted: 06/18/2007] [Indexed: 01/11/2023]
Abstract
The alveolar surface comprises >99% of the internal surface area of the lungs. At birth, the fetal lung rapidly converts from a state of net fluid secretion, which is necessary for normal fetal lung development, to a state in which there is a minimal amount of alveolar liquid. The alveolar surface epithelium facing the air compartment is composed of TI and TII cells. The morphometric characteristics of both cell types are fairly constant over a range of mammalian species varying in body weight by a factor of approximately 50,000. From the conservation of size and shape across species, one may infer that both TI and TII cells also have important conserved functions. The regulation of alveolar ion and liquid transport has been extensively investigated using a variety of experimental models, including whole animal, isolated lung, isolated cell, and cultured cell model systems, each with their inherent strengths and weaknesses. The results obtained with different model systems and a variety of different species point to both interesting parallels and some surprising differences. Sometimes it has been difficult to reconcile results obtained with different model systems. In this section, the primary focus will be on aspects of alveolar ion and liquid transport under normal physiologic conditions, emphasizing newer data and describing evolving paradigms of lung ion and fluid transport. We will highlight some of the unanswered questions, outline the similarities and differences in results obtained with different model systems, and describe some of the complex and interweaving regulatory networks.
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Affiliation(s)
- Leland G Dobbs
- Department of Medicine, University of California San Francisco, San Francisco, CA 94118, USA.
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Berthiaume Y, Matthay MA. Alveolar edema fluid clearance and acute lung injury. Respir Physiol Neurobiol 2007; 159:350-9. [PMID: 17604701 PMCID: PMC2682357 DOI: 10.1016/j.resp.2007.05.010] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2007] [Revised: 04/18/2007] [Accepted: 05/11/2007] [Indexed: 01/11/2023]
Abstract
Although lung-protective ventilation strategies have substantially reduced mortality of acute lung injury patients there is still a need for new therapies that can further decrease mortality in patients with acute lung injury. Studies of epithelial ion and fluid transport across the distal pulmonary epithelia have provided important new concepts regarding potential new therapies for acute lung injury. Overall, there is convincing evidence that the alveolar epithelium is not only a tight epithelial barrier that resists the movement of edema fluid into the alveoli, but it is also actively involved in the transport of ions and solutes, a process that is essential for edema fluid clearance and the resolution of acute lung injury. The objective of this article is to consider some areas of recent progress in the field of alveolar fluid transport under normal and pathologic conditions. Vectorial ion transport across the alveolar and distal airway epithelia is the primary determinant of alveolar fluid clearance. The general paradigm is that active Na(+) and Cl(-) transport drives net alveolar fluid clearance, as demonstrated in several different species, including the human lung. Although these transport processes can be impaired in severe lung injury, multiple experimental studies suggest that upregulation of Na(+) and Cl(-) transport might be an effective therapy in acute lung injury. We will review mechanisms involved in pharmacological modulation of ion transport in lung injury with a special focus on the use of beta-adrenergic agonists which has generated considerable interest and is a promising therapy for clinical acute lung injury.
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Affiliation(s)
- Yves Berthiaume
- Département de médecine et Centre de recherche du Centre Hospitalier de l'Université de Montréal, Université de Montréal, Montréal, Québec, Canada.
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