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Makena P, Kikalova T, Prasad GL, Baxter SA. Oxidative Stress and Lung Fibrosis: Towards an Adverse Outcome Pathway. Int J Mol Sci 2023; 24:12490. [PMID: 37569865 PMCID: PMC10419527 DOI: 10.3390/ijms241512490] [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: 06/30/2023] [Revised: 08/01/2023] [Accepted: 08/03/2023] [Indexed: 08/13/2023] Open
Abstract
Lung fibrosis is a progressive fatal disease in which deregulated wound healing of lung epithelial cells drives progressive fibrotic changes. Persistent lung injury due to oxidative stress and chronic inflammation are central features of lung fibrosis. Chronic cigarette smoking causes oxidative stress and is a major risk factor for lung fibrosis. The objective of this manuscript is to develop an adverse outcome pathway (AOP) that serves as a framework for investigation of the mechanisms of lung fibrosis due to lung injury caused by inhaled toxicants, including cigarette smoke. Based on the weight of evidence, oxidative stress is proposed as a molecular initiating event (MIE) which leads to increased secretion of proinflammatory and profibrotic mediators (key event 1 (KE1)). At the cellular level, these proinflammatory signals induce the recruitment of inflammatory cells (KE2), which in turn, increase fibroblast proliferation and myofibroblast differentiation (KE3). At the tissue level, an increase in extracellular matrix deposition (KE4) subsequently culminates in lung fibrosis, the adverse outcome. We have also defined a new KE relationship between the MIE and KE3. This AOP provides a mechanistic platform to understand and evaluate how persistent oxidative stress from lung injury may develop into lung fibrosis.
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Affiliation(s)
- Patrudu Makena
- RAI Services Company, P.O. Box 1487, Winston-Salem, NC 27102, USA;
| | - Tatiana Kikalova
- Clarivate Analytics, 1500 Spring Garden, Philadelphia, PA 19130, USA
| | - Gaddamanugu L. Prasad
- Former Employee of RAI Services Company, Winston-Salem, NC 27101, USA
- Prasad Scientific Consulting LLC, 490 Friendship Place Ct, Lewisville, NC 27023, USA
| | - Sarah A. Baxter
- RAI Services Company, P.O. Box 1487, Winston-Salem, NC 27102, USA;
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Cadiz L, Jonz MG. A comparative perspective on lung and gill regeneration. ACTA ACUST UNITED AC 2020; 223:223/19/jeb226076. [PMID: 33037099 DOI: 10.1242/jeb.226076] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The ability to continuously grow and regenerate the gills throughout life is a remarkable property of fish and amphibians. Considering that gill regeneration was first described over one century ago, it is surprising that the underlying mechanisms of cell and tissue replacement in the gills remain poorly understood. By contrast, the mammalian lung is a largely quiescent organ in adults but is capable of facultative regeneration following injury. In the course of the past decade, it has been recognized that lungs contain a population of stem or progenitor cells with an extensive ability to restore tissue; however, despite recent advances in regenerative biology of the lung, the signaling pathways that underlie regeneration are poorly understood. In this Review, we discuss the common evolutionary and embryological origins shared by gills and mammalian lungs. These are evident in homologies in tissue structure, cell populations, cellular function and genetic pathways. An integration of the literature on gill and lung regeneration in vertebrates is presented using a comparative approach in order to outline the challenges that remain in these areas, and to highlight the importance of using aquatic vertebrates as model organisms. The study of gill regeneration in fish and amphibians, which have a high regenerative potential and for which genetic tools are widely available, represents a unique opportunity to uncover common signaling mechanisms that may be important for regeneration of respiratory organs in all vertebrates. This may lead to new advances in tissue repair following lung disease.
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Affiliation(s)
- Laura Cadiz
- Department of Biology, University of Ottawa, 30 Marie Curie Pvt., Ottawa, ON, Canada, K1N 6N5
| | - Michael G Jonz
- Department of Biology, University of Ottawa, 30 Marie Curie Pvt., Ottawa, ON, Canada, K1N 6N5
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Yao Y, Gu Y, Yang M, Cao D, Wu F. The Gene Expression Biomarkers for Chronic Obstructive Pulmonary Disease and Interstitial Lung Disease. Front Genet 2019; 10:1154. [PMID: 31824564 PMCID: PMC6879656 DOI: 10.3389/fgene.2019.01154] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 10/22/2019] [Indexed: 01/01/2023] Open
Abstract
COPD (chronic obstructive pulmonary disease) and ILD (interstitial lung disease) are two common respiratory diseases. They share similar clinical traits but require different therapeutic treatments. Identifying the biomarkers that are differentially expressed between them will not only help the diagnosis of COPD and ILD, but also provide candidate drug targets that may facilitate the development of new treatment for COPD and ILD. Due to the irreversible complex pathological changes of COPD, there are very limited therapeutic options for COPD patients. In this study, we analyzed the gene expression profiles of two datasets: one training dataset that includes 144 COPD patients and 194 ILD patients, and one test dataset that includes 75 COPD patients and 61 ILD patients. Advanced feature selection methods, mRMR (minimal Redundancy Maximal Relevance) and incremental feature selection (IFS), were applied to identify the 38-gene biomarker. An SVM (support vector machine) classifier was built based on the 38-gene biomarker. Its accuracy, sensitivity, and specificity on training dataset evaluated by leave one out cross-validation were 0.905, 0.896, and 0.912, respectively. And on independent test dataset, the accuracy, sensitivity, and specificity on were as great as and were 0.904, 0.933, and 0.869, respectively. The biological function analysis of the 38 genes indicated that many of them can be potential treatment targets that may benefit COPD and ILD patients.
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Affiliation(s)
- Yangwei Yao
- Department of Pulmonary and Critical Care Medicine, The Second Hospital of Jiaxing, Jiaxing, China
| | - Yangyang Gu
- Department of Pulmonary and Critical Care Medicine, The Second Hospital of Jiaxing, Jiaxing, China
| | - Meng Yang
- Department of Pulmonary and Critical Care Medicine, The Second Hospital of Jiaxing, Jiaxing, China
| | - Dakui Cao
- Department of Pulmonary and Critical Care Medicine, The Second Hospital of Jiaxing, Jiaxing, China
| | - Fengjie Wu
- Department of Pulmonary and Critical Care Medicine, The Second Hospital of Jiaxing, Jiaxing, China
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Do DC, Mu J, Ke X, Sachdeva K, Qin Z, Wan M, Ishmael FT, Gao P. miR-511-3p protects against cockroach allergen-induced lung inflammation by antagonizing CCL2. JCI Insight 2019; 4:126832. [PMID: 31536479 DOI: 10.1172/jci.insight.126832] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 09/12/2019] [Indexed: 02/06/2023] Open
Abstract
miR-511-3p, encoded by CD206/Mrc1, was demonstrated to reduce allergic inflammation and promote alternative (M2) macrophage polarization. Here, we sought to elucidate the fundamental mechanism by which miR-511-3p attenuates allergic inflammation and promotes macrophage polarization. Compared with WT mice, the allergen-challenged Mrc1-/- mice showed increased airway hyperresponsiveness (AHR) and inflammation. However, this increased AHR and inflammation were significantly attenuated when these mice were pretransduced with adeno-associated virus-miR-511-3p (AAV-miR-511-3p). Gene expression profiling of macrophages identified Ccl2 as one of the major genes that was highly expressed in M2 macrophages but antagonized by miR-511-3p. The interaction between miR-511-3p and Ccl2 was confirmed by in silico analysis and mRNA-miR pulldown assay. Further evidence for the inhibition of Ccl2 by miR-511-3p was given by reduced levels of Ccl2 in supernatants of miR-511-3p-transduced macrophages and in bronchoalveolar lavage fluids of AAV-miR-511-3p-infected Mrc1-/- mice. Mechanistically, we demonstrated that Ccl2 promotes M1 macrophage polarization by activating RhoA signaling through Ccr2. The interaction between Ccr2 and RhoA was also supported by coimmunoprecipitation assay. Importantly, inhibition of RhoA signaling suppressed cockroach allergen-induced AHR and lung inflammation. These findings suggest a potentially novel mechanism by which miR-511-3p regulates allergic inflammation and macrophage polarization by targeting Ccl2 and its downstream Ccr2/RhoA axis.
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Affiliation(s)
- Danh C Do
- Johns Hopkins Asthma and Allergy Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Jie Mu
- Johns Hopkins Asthma and Allergy Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,Department of Anesthesiology, West China School of Medicine, Sichuan University, Chengdu, China
| | - Xia Ke
- Department of Otorhinolaryngology, First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Karan Sachdeva
- Johns Hopkins Asthma and Allergy Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Zili Qin
- Otorhinolaryngology Hospital, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Mei Wan
- Department of Orthopedic Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Faoud T Ishmael
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, Pennsylvania State University Milton S. Hershey Medical Center, Hershey, Pennsylvania, USA
| | - Peisong Gao
- Johns Hopkins Asthma and Allergy Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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Schiffhauer ES, Vij N, Kovbasnjuk O, Kang PW, Walker D, Lee S, Zeitlin PL. Dual activation of CFTR and CLCN2 by lubiprostone in murine nasal epithelia. Am J Physiol Lung Cell Mol Physiol 2013; 304:L324-31. [PMID: 23316067 DOI: 10.1152/ajplung.00277.2012] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Multiple sodium and chloride channels on the apical surface of nasal epithelial cells contribute to periciliary fluid homeostasis, a function that is disrupted in patients with cystic fibrosis (CF). Among these channels is the chloride channel CLCN2, which has been studied as a potential alternative chloride efflux pathway in the absence of CFTR. The object of the present study was to use the nasal potential difference test (NPD) to quantify CLCN2 function in an epithelial-directed TetOn CLCN2 transgenic mouse model (TGN-K18rtTA-hCLCN2) by using the putative CLCN2 pharmacological agonist lubiprostone and peptide inhibitor GaTx2. Lubiprostone significantly increased chloride transport in the CLCN2-overexpressing mice following activation of the transgene by doxycycline. This response to lubiprostone was significantly inhibited by GaTx2 after CLCN2 activation in TGN-CLCN2 mice. Cftr(-/-) and Clc2(-/-) mice showed hyperpolarization indicative of chloride efflux in response to lubiprostone, which was fully inhibited by GaTx2 and CFTR inhibitor 172 + GlyH-101, respectively. Our study reveals lubiprostone as a pharmacological activator of both CFTR and CLCN2. Overexpression and activation of CLCN2 leads to improved mouse NPD readings, suggesting it is available as an alternative pathway for epithelial chloride secretion in murine airways. The utilization of CLCN2 as an alternative chloride efflux channel could provide clinical benefit to patients with CF, especially if the pharmacological activator is administered as an aerosol.
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Affiliation(s)
- Eric S Schiffhauer
- Department of Pediatrics, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
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Ringman Uggla A, Zelenina M, Eklöf AC, Aperia A, Frenckner B. Expression of chloride channels in trachea-occluded hyperplastic lungs and nitrofen-induced hypoplastic lungs in rats. Pediatr Surg Int 2009; 25:799-806. [PMID: 19652985 DOI: 10.1007/s00383-009-2423-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/17/2009] [Indexed: 11/29/2022]
Abstract
BACKGROUND Congenital diaphragmatic hernia is accompanied by pulmonary hypoplasia. Fetal lung growth is dependent on the secretion of lung liquid, in which Cl(-) secretion by the pulmonary epithelium plays a crucial role. A decrease of lung liquid production during fetal development renders marked pulmonary hypoplasia, while accelerated fetal lung growth in the form of pulmonary hyperplasia can be achieved by in utero tracheal occlusion (TO). Cl(-) secretion presumably involves NKCC-1, the primary basolateral Cl(-) entry pathway in airway epithelia, coupled to an apical Cl(-) exit pathway. The chloride channels ClC-2, -3 and -5, members of the CLC gene family, are all localized to the apical membrane of fetal respiratory epithelia, which makes them possible candidates for being mediators of fetal apical Cl(-) secretion. The aim of the study was to examine the potential of ClC-2, -3 and -5 as alternative apical airway epithelial Cl(-) channels in normal lung development and their possible role in the development of hypoplastic lungs in CDH. We also wanted to examine ClC-2, -3 and -5 together with the NKCC-1 in hyperplastic lungs created by TO. METHODS Pregnant Sprague-Dawley rat dams were given nitrofen on gestational day 9.5 to induce pulmonary hypoplasia. Controls were given only olive oil. The rat fetuses were removed on days 17, 19 and 21. Hyperplastic lungs were created by intrauterine TO of rat fetuses on day 19 and the lungs were harvested on day 21. The pulmonary expression of ClC-2, -3, -5 and NKCC-1 was then analyzed using Western blot. RESULTS We found that the temporal expression of ClC-2 and -3 in normal fetal lungs points toward a developmental regulation. ClC-2 and -3 were also both down-regulated on day 21 in hypoplastic CDH lungs. In TO induced hyperplastic lungs, the levels of ClC-2 were found to be significantly up-regulated. NKCC-1 showed a tendency toward up-regulation in hyperplastic lungs, while ClC-3 showed a tendency to be down-regulated, but no statistically significant changes could be seen. There was no difference between controls and any of the groups for the expression of ClC-5. CONCLUSION We show that the developmental changes in ClC-2 and ClC-3 protein expression are negatively affected in hypoplastic CDH lungs. Lung hyperplasia created by TO up-regulates the expression of ClC-2. ClC-2 is therefore an interesting potential target in the development of novel, non-invasive, therapies for CDH treatment.
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Affiliation(s)
- Andreas Ringman Uggla
- Research Laboratory Q2:09, Department of Woman and Child Health, Nordic Centre of Excellence for Research in Water Imbalance Related Disorders, Astrid Lindgren Children's Hospital, Karolinska University Hospital, Karolinska Institutet, 171 76 Stockholm, Sweden.
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7
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Jin N, Guo Y, Sun P, Bell A, Chintagari NR, Bhaskaran M, Rains K, Baviskar P, Chen Z, Weng T, Liu L. Ionotropic GABA receptor expression in the lung during development. Gene Expr Patterns 2008; 8:397-403. [PMID: 18539546 DOI: 10.1016/j.gep.2008.04.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2007] [Revised: 04/04/2008] [Accepted: 04/27/2008] [Indexed: 11/28/2022]
Abstract
Cl(-) transport is essential for lung development. Because gamma-aminobutyric acid (GABA) receptors allow the flow of negatively-charged Cl(-) ions across the cell membrane, we hypothesized that the expression of ionotropic GABA receptors are regulated in the lungs during development. We identified 17 GABA receptor subunits in the lungs by real-time PCR. These subunits were categorized into four groups: Group 1 had high mRNA expression during fetal stages and low in adults; Group 2 had steady expression to adult stages with a slight up-regulation at birth; Group 3 showed an increasing expression from fetal to adult lungs; and Group 4 displayed irregular mRNA fluctuations. The protein levels of selected subunits were also determined by Western blots and some subunits had protein levels that corresponded to mRNA levels. Further studied subunits were primarily localized in epithelial cells in the developing lung with differential mRNA expression between isolated cells and whole lung tissues. Our results add to the knowledge of GABA receptor expression in the lung during development.
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Affiliation(s)
- Nili Jin
- Department of Physiological Sciences, Oklahoma State University, 264 McElroy Hall, Stillwater, OK 74078, USA
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Itani OA, Lamb FS, Melvin JE, Welsh MJ. Basolateral chloride current in human airway epithelia. Am J Physiol Lung Cell Mol Physiol 2007; 293:L991-9. [PMID: 17660331 DOI: 10.1152/ajplung.00077.2007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Electrolyte transport by airway epithelia regulates the quantity and composition of liquid covering the airways. Previous data indicate that airway epithelia can absorb NaCl. At the apical membrane, cystic fibrosis transmembrane conductance regulator (CFTR) provides a pathway for Cl(-) absorption. However, the pathways for basolateral Cl(-) exit are not well understood. Earlier studies, predominantly in cell lines, have reported that the basolateral membrane contains a Cl(-) conductance. However, the properties have varied substantially in different epithelia. To better understand the basolateral Cl(-) conductance in airway epithelia, we studied primary cultures of well-differentiated human airway epithelia. The basolateral membrane contained a Cl(-) current that was inhibited by 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS). The current-voltage relationship was nearly linear, and the halide selectivity was Cl(-) > Br(-) >> I(-). Several signaling pathways increased the current, including elevation of cellular levels of cAMP, activation of protein kinase C (PKC), and reduction of pH. In contrast, increasing cell Ca(2+) and inducing cell swelling had no effect. The basolateral Cl(-) current was present in both cystic fibrosis (CF) and non-CF airway epithelia. Likewise, airway epithelia from wild-type mice and mice with disrupted genes for ClC-2 or ClC-3 all showed similar Cl(-) currents. These data suggest that the basolateral membrane of airway epithelia possesses a Cl(-) conductance that is not due to CFTR, ClC-2, or ClC-3. Its regulation by cAMP and PKC signaling pathways suggests that coordinated regulation of Cl(-) conductance in both apical and basolateral membranes may be important in controlling transepithelial Cl(-) movement.
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Affiliation(s)
- Omar A Itani
- Howard Hughes Medical Institute, Univ. of Iowa, Iowa City, IA 52242, USA
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Foley KF, Pantano C, Ciolino A, Mawe GM. IFN-gamma and TNF-alpha decrease serotonin transporter function and expression in Caco2 cells. Am J Physiol Gastrointest Liver Physiol 2007; 292:G779-84. [PMID: 17170025 DOI: 10.1152/ajpgi.00470.2006] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Recent studies have shown that mucosal serotonin (5-HT) transporter (SERT) expression is decreased in animal models of colitis, as well as in the colonic mucosa of humans with ulcerative colitis and irritable bowel syndrome. Altered SERT function or expression may underlie the altered motility, secretion, and sensation seen in these inflammatory gut disorders. In an effort to elucidate possible mediators of SERT downregulation, we treated cultured colonic epithelial cells (Caco2) with conditioned medium from activated human lymphocytes. Application of the conditioned medium caused a decrease in fluoxetine-sensitive [(3)H]5-HT uptake. Individual proinflammatory agents were then tested for their ability to affect uptake. Cells were treated for 48 or 72 h with PGE(2) (10 microM), IFN-gamma (500 ng/ml), TNF-alpha (50 ng/ml), IL-12 (50 ng/ml), or the nitric oxide-releasing agent S-nitrosoglutathione (GSNO; 100 microM). [(3)H]5-HT uptake was then measured. Neither PGE nor IL-12 had any effect on [(3)H]5-HT uptake, and GSNO increased uptake. However, after 3-day incubation, both TNF-alpha and IFN-gamma elicited significant decreases in SERT function. Neither TNF-alpha nor IFN-gamma were cytotoxic when used for this period of time and at these concentrations. These two cytokines also induced decreases in SERT mRNA and protein levels. By altering SERT expression, TNF-alpha and IFN-gamma could contribute to the altered motility and expression seen in vivo in ulcerative colitis or irritable bowel syndrome.
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Affiliation(s)
- Kevin F Foley
- Department of Medical Laboratory and Radiation Sciences, the University of Vermont, Burlington, VT 05405, USA
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Blaisdell CJ, Howard TD, Stern A, Bamford P, Bleecker ER, Stine OC. CLC-2 single nucleotide polymorphisms (SNPs) as potential modifiers of cystic fibrosis disease severity. BMC MEDICAL GENETICS 2004; 5:26. [PMID: 15507145 PMCID: PMC526769 DOI: 10.1186/1471-2350-5-26] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/22/2004] [Accepted: 10/26/2004] [Indexed: 11/24/2022]
Abstract
Background Cystic fibrosis (CF) lung disease manifest by impaired chloride secretion leads to eventual respiratory failure. Candidate genes that may modify CF lung disease severity include alternative chloride channels. The objectives of this study are to identify single nucleotide polymorphisms (SNPs) in the airway epithelial chloride channel, CLC-2, and correlate these polymorphisms with CF lung disease. Methods The CLC-2 promoter, intron 1 and exon 20 were examined for SNPs in adult CF dF508/dF508 homozygotes with mild and severe lung disease (forced expiratory volume at one second (FEV1) > 70% and < 40%). Results PCR amplification of genomic CLC-2 and sequence analysis revealed 1 polymorphism in the hClC -2 promoter, 4 in intron 1, and none in exon 20. Fisher's analysis within this data set, did not demonstrate a significant relationship between the severity of lung disease and SNPs in the CLC-2 gene. Conclusions CLC-2 is not a key modifier gene of CF lung phenotype. Further studies evaluating other phenotypes associated with CF may be useful in the future to assess the ability of CLC-2 to modify CF disease severity.
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Affiliation(s)
- Carol J Blaisdell
- Department of Genetics, School of Medicine, University of Maryland, Howard Hall 596, 660 W. Redwood St., Baltimore, Maryland, USA
| | - Timothy D Howard
- Center for Human Genomics, Wake Forest University School of Medicine, Medical Center Blvd., Winston-Salem, North Carolina, 27157 USA
| | - Augustus Stern
- School of Medicine, University of Maryland, Howard Hall 324, Baltimore, Maryland, USA
| | - Penelope Bamford
- Department of Pediatrics, School of Medicine, University of Maryland, Bressler 10–019, 655 W. Baltimore St., Baltimore, Maryland, 21201 USA
| | - Eugene R Bleecker
- Center for Human Genomics, Wake Forest University School of Medicine, Medical Center Blvd., Winston-Salem, North Carolina, 27157 USA
| | - O Colin Stine
- Department of Genetics, School of Medicine, University of Maryland, Howard Hall 596, 660 W. Redwood St., Baltimore, Maryland, USA
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Blaisdell CJ, Morales MM, Andrade ACO, Bamford P, Wasicko M, Welling P. Inhibition of CLC-2 chloride channel expression interrupts expansion of fetal lung cysts. Am J Physiol Lung Cell Mol Physiol 2004; 286:L420-6. [PMID: 14711803 DOI: 10.1152/ajplung.00113.2003] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Normal lung morphogenesis is dependent on chloride-driven fluid transport. The molecular identity of essential fetal lung chloride channel(s) has not been elucidated. CLC-2 is a chloride channel, which is expressed on the apical surface of the developing respiratory epithelium. CLC-2-like pH-dependent chloride secretion exists in fetal airway cells. We used a 14-day fetal rat lung submersion culture model to examine the role of CLC-2 in lung development. In this model, the excised fetal lung continues to grow, secrete fluid, and become progressively cystic in morphology (26). We inhibited CLC-2 expression in these explants, using antisense oligonucleotides, and found that lung cyst morphology was disrupted. In addition, transepithelial voltage (V(t)) of lung explants transfected with antisense CLC-2 was inhibited with V(t) = -1.5 +/- 0.2 mV (means + SE) compared with -3.7 +/- 0.3 mV (means + SE) for mock-transfected controls and -3.3 +/- 0.3 mV (means + SE) for nonsense oligodeoxynucleotide-transfected controls. This suggests that CLC-2 is important for fetal lung fluid production and that it may play a role in normal lung morphogenesis.
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Affiliation(s)
- Carol J Blaisdell
- Department of Pediatrics, University of Maryland at Baltimore, Baltimore, MD 21201, USA.
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12
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Jouret F, Igarashi T, Gofflot F, Wilson PD, Karet FE, Thakker RV, Devuyst O. Comparative ontogeny, processing, and segmental distribution of the renal chloride channel, ClC-5. Kidney Int 2004; 65:198-208. [PMID: 14675051 DOI: 10.1111/j.1523-1755.2004.00360.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND The renal chloride channel ClC-5, which is responsible for Dent's disease, is coexpressed with the vacuolar H+-ATPase in proximal tubules (PT) and alpha-type intercalated cells (IC) of the mature kidney. Neonatal cases of Dent's disease suggest that ClC-5 distribution must be acquired before birth. However, the ontogeny of ClC-5, and its processing and segmental distribution with respect to related proteins during nephrogenesis remain unknown. METHODS Immunoblotting, real-time polymerase chain reaction (RT-PCR), immunostaining, and deglycosylation studies were used to investigate the expression, distribution, and maturation of ClC-5 during mouse and human nephrogenesis, in comparison with H+-ATPase, type II carbonic anhydrase (CAII), and aquaporin-1 (AQP1). RESULTS An early induction (E13.5-E14.5) of ClC-5 was observed in mouse kidney, with persistence at high levels through late nephrogenesis. This pattern contrasted with the progressive expression of H+-ATPase and AQP1, and the postnatal upregulation of CAII. Immunostaining showed expression of ClC-5 in ureteric buds and, from E14.5, its location in developing PT. From E15.5, ClC-5 codistributed with H+-ATPase in PT cells and alpha-type IC. In the human kidney, ClC-5 was detected from 12 gestation weeks; its distribution was similar to that observed in mouse, except for a later detection in IC. Although mouse and human ClC-5 proteins are glycosylated, biochemical differences between fetal and adult proteins were observed in both species. CONCLUSION The segmental expression of ClC-5 and H+-ATPase is essentially achieved during early nephrogenesis, in parallel with the onset of glomerular filtration. These data give insight into PT and IC maturation, and explain early phenotypic variants of Dent's disease.
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Affiliation(s)
- François Jouret
- Division of Nephrology and Laboratory of Developmental Genetics, Université Catholique de Louvain, Brussels, Belgium
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Blouquit S, Morel H, Hinnrasky J, Naline E, Puchelle E, Chinet T. Characterization of ion and fluid transport in human bronchioles. Am J Respir Cell Mol Biol 2002; 27:503-10. [PMID: 12356585 DOI: 10.1165/rcmb.4869] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The regulation of the volume and composition of airway surface liquid is achieved through epithelial ion transport processes. In humans, these processes have been characterized in proximal but not distal airways. Segments of human bronchioles were dissected from surgically removed lung pieces. The transmural potential difference of microperfused bronchioles was inhibited by luminal exposure to amiloride and increased when exposed to the Cl secretagogues forskolin and ATP in the presence of amiloride. Human bronchiolar epithelial cells were cultured on permeable supports and studied in Ussing chambers. They generated a short circuit current (Isc) that decreased in response to amiloride and increased in response to forskolin and to ATP in the presence of amiloride. In low-Cl Kreb's Ringer bicarbonate, the baseline Isc and amiloride-induced decrease in Isc were not different, whereas the forskolin- and ATP-induced increases in Isc were smaller. Fluid transport measurement in excised bronchioles revealed a basal absorptive flow that was reduced by amiloride, whereas forskolin and ATP combined induced a secretory flow in the presence of amiloride. We conclude that human bronchioles actively absorb Na and fluid in unstimulated conditions and are capable of active Cl and fluid secretion when exposed to forskolin and to ATP.
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Affiliation(s)
- Sabine Blouquit
- Laboratoire de Biologie et Pharmacologie des Epithéliums Respiratoires, Université Paris V, Boulogne, France
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Lipecka J, Bali M, Thomas A, Fanen P, Edelman A, Fritsch J. Distribution of ClC-2 chloride channel in rat and human epithelial tissues. Am J Physiol Cell Physiol 2002; 282:C805-16. [PMID: 11880269 DOI: 10.1152/ajpcell.00291.2001] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The ubiquitous ClC-2 Cl(-) channel is thought to contribute to epithelial Cl(-) secretion, but the distribution of the ClC-2 protein in human epithelia has not been investigated. We have studied the distribution of ClC-2 in adult human and rat intestine and airways by immunoblotting and confocal microscopy. In the rat, ClC-2 was present in the lateral membranes of villus enterocytes and was predominant at the basolateral membranes of luminal colon enterocytes. The expression pattern of ClC-2 in the human intestine differed significantly, because ClC-2 was mainly detected in a supranuclear compartment of colon cells. We found significant expression of ClC-2 at the apex of ciliated cells in both rat and human airways. These results show that the distribution of ClC-2 in airways is consistent with participation of ClC-2 channels in Cl(-) secretion and indicate that extrapolation of results from studies of ClC-2 function in rat intestine to human intestine is not straightforward.
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Affiliation(s)
- Joanna Lipecka
- Institut National de la Santé et de la Recherche Médicale (INSERM), Unité 467, Faculté de Médecine Necker-Enfants Malades, 75015 Paris, France
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Edmonds RD, Silva IV, Guggino WB, Butler RB, Zeitlin PL, Blaisdell CJ. ClC-5: ontogeny of an alternative chloride channel in respiratory epithelia. Am J Physiol Lung Cell Mol Physiol 2002; 282:L501-7. [PMID: 11839544 DOI: 10.1152/ajplung.00207.2001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Chloride transport is critical to many functions of the lung. Molecular defects in the best-known chloride channel, cystic fibrosis transmembrane conductance regulator (CFTR), lead to impaired function of airway defensins, hydration of airway surface fluid, and mucociliary clearance leading to chronic lung disease, and premature death, but do not cause defects in lung development. We examined the expression of one member of the ClC family of volume- and voltage-regulated channels using the ribonuclease protection assay and Western blot analysis in rats. ClC-5 mRNA and protein are most strongly expressed in the fetal lung, and expression is maintained although downregulated postnatally. In addition, using immunocytochemistry, we find that ClC-5 is predominantly expressed along the luminal surface of the airway epithelium, suggesting that ClC-5 may participate in lung chloride secretion. Identifying candidate genes for critical ion transport functions is essential for understanding normal lung morphogenesis and the pathophysiology of several lung diseases. In addition, the manipulation of non-CFTR chloride channels may provide a viable approach for treating cystic fibrosis lung disease.
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Affiliation(s)
- Rebecca D Edmonds
- Department of Pediatrics, Eudowood Division of Respiratory Sciences, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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O'Brodovich H. Fetal lung liquid secretion: insights using the tools of inhibitors and genetic knock-out experiments. Am J Respir Cell Mol Biol 2001; 25:8-10. [PMID: 11472968 DOI: 10.1165/ajrcmb.25.1.f211] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- H O'Brodovich
- Lung Biology Programme of the Hospital for Sick Children Research Institute, CIHR Group in Lung Development, University of Toronto, Toronto, Ontario, Canada M5G-1X8.
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