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Kashlan OB, Wang XP, Sheng S, Kleyman TR. Epithelial Na + Channels Function as Extracellular Sensors. Compr Physiol 2024; 14:1-41. [PMID: 39109974 PMCID: PMC11309579 DOI: 10.1002/cphy.c230015] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/10/2024]
Abstract
The epithelial Na + channel (ENaC) resides on the apical surfaces of specific epithelia in vertebrates and plays a critical role in extracellular fluid homeostasis. Evidence that ENaC senses the external environment emerged well before the molecular identity of the channel was reported three decades ago. This article discusses progress toward elucidating the mechanisms through which specific external factors regulate ENaC function, highlighting insights gained from structural studies of ENaC and related family members. It also reviews our understanding of the role of ENaC regulation by the extracellular environment in physiology and disease. After familiarizing the reader with the channel's physiological roles and structure, we describe the central role protein allostery plays in ENaC's sensitivity to the external environment. We then discuss each of the extracellular factors that directly regulate the channel: proteases, cations and anions, shear stress, and other regulators specific to particular extracellular compartments. For each regulator, we discuss the initial observations that led to discovery, studies investigating molecular mechanism, and the physiological and pathophysiological implications of regulation. © 2024 American Physiological Society. Compr Physiol 14:5407-5447, 2024.
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Affiliation(s)
- Ossama B. Kashlan
- Department of Medicine, Renal-Electrolyte Division,
University of Pittsburgh, Pittsburgh, Pennsylvania
- Department of Computational and Systems Biology, University
of Pittsburgh, Pittsburgh, Pennsylvania
| | - Xue-Ping Wang
- Department of Medicine, Renal-Electrolyte Division,
University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Shaohu Sheng
- Department of Medicine, Renal-Electrolyte Division,
University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Thomas R. Kleyman
- Department of Medicine, Renal-Electrolyte Division,
University of Pittsburgh, Pittsburgh, Pennsylvania
- Department of Cell Biology, University of Pittsburgh,
Pittsburgh, Pennsylvania
- Department of Pharmacology and Chemical Biology, University
of Pittsburgh, Pittsburgh, Pennsylvania
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2
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Liu Q, Wang Z, Zhang W. The Multifunctional Roles of Short Palate, Lung, and Nasal Epithelium Clone 1 in Regulating Airway Surface Liquid and Participating in Airway Host Defense. J Interferon Cytokine Res 2021; 41:139-148. [PMID: 33885339 DOI: 10.1089/jir.2020.0141] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Short palate, lung, and nasal epithelium clone 1 (SPLUNC1) is a kind of secretory protein, and gets expressed abundantly in normal respiratory epithelium of humans. As a natural immune molecule, SPLUNC1 is proved to be involved in inflammatory response and airway host defense. This review focuses on summarizing and discussing the role of SPLUNC1 in regulating airway surface liquid (ASL) and participating in airway host defense. PubMed and MEDLINE were used for searching and identifying the data in this review. The domain of bactericidal/permeability-increasing protein in SPLUNC1 and the α-helix, α4, are essential for SPLUNC1 to exert biological activities. As a natural innate immune molecule, SPLUNC1 plays a significant role in inflammatory response and airway host defense. Its special expression patterns are not only observed in physiological conditions, but also in some respiratory diseases. The mechanisms of SPLUNC1 in airway host defense include modulating ASL volume, acting as a surfactant protein, inhibiting biofilm formation, as well as regulating ASL compositions, such as LL-37, mucins, Neutrophil elastase, and inflammatory cytokines. Besides, potential correlations are found among these different mechanisms, especially among different ASL compositions, which should be further explored in more systematical frameworks. In this review, we summarize the structural characteristics and expression patterns of SPLUNC1 briefly, and mainly discuss the mechanisms of SPLUNC1 exerted in host defense, aiming to provide a theoretical basis and a novel target for future studies and clinical treatments.
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Affiliation(s)
- Qingluan Liu
- Department of Medical Laboratory Science, The Third Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Zhicheng Wang
- Department of Medical Laboratory Science, The Third Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Wenling Zhang
- Department of Medical Laboratory Science, The Third Xiangya Hospital, Central South University, Changsha, Hunan, China
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3
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Sala V, Murabito A, Ghigo A. Inhaled Biologicals for the Treatment of Cystic Fibrosis. ACTA ACUST UNITED AC 2020; 13:19-26. [PMID: 30318010 PMCID: PMC6751348 DOI: 10.2174/1872213x12666181012101444] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 10/09/2018] [Accepted: 10/09/2018] [Indexed: 12/20/2022]
Abstract
Background: Cystic Fibrosis (CF), one of the most frequent genetic diseases, is characterized by the production of viscous mucus in several organs. In the lungs, mucus clogs the airways and traps bacteria, leading to recurrent/resistant infections and lung damage. For cystic fibrosis patients, respiratory failure is still lethal in early adulthood since available treatments display incomplete efficacy. Objective: The objective of this review is to extend the current knowledge in the field of available treat-ments for cystic fibrosis. A special focus has been given to inhaled peptide-based drugs. Methods: The current review is based on recent and/or relevant literature and patents already available in various scientific databases, which include PubMed, PubMed Central, Patentscope and Science Direct. The information obtained through these diverse databases is compiled, critically interpreted and presented in the current study. An in-depth but not systematic approach to the specific research question has been adopted. Results: Recently, peptides have been proposed as possible pharmacologic agents for the treatment of respiratory diseases. Of note, peptides are suitable to be administered by inhalation to maximize efficacy and reduce systemic side effects. Moreover, innovative delivery carriers have been developed for drug administration through inhalation, allowing not only protection against proteolysis, but also a prolonged and controlled release. Conclusion: Here, we summarize newly patented peptides that have been developed in the last few years and advanced technologies for inhaled drug delivery to treat cystic fibrosis.
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Affiliation(s)
- Valentina Sala
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology Center, University of Torino, Torino, Italy.,S.C. Medicina d'Urgenza, A.O.U. Città della Salute e della Scienza, Molinette Hospital, Torino, Italy
| | - Alessandra Murabito
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology Center, University of Torino, Torino, Italy
| | - Alessandra Ghigo
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology Center, University of Torino, Torino, Italy
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Walton WG, Ahmad S, Little MR, Kim CS, Tyrrell J, Lin Q, Di YP, Tarran R, Redinbo MR. Structural Features Essential to the Antimicrobial Functions of Human SPLUNC1. Biochemistry 2016; 55:2979-91. [PMID: 27145151 PMCID: PMC4887393 DOI: 10.1021/acs.biochem.6b00271] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
SPLUNC1 is an abundantly secreted innate immune protein in the mammalian respiratory tract that exerts bacteriostatic and antibiofilm effects, binds to lipopolysaccharide (LPS), and acts as a fluid-spreading surfactant. Here, we unravel the structural elements essential for the surfactant and antimicrobial functions of human SPLUNC1 (short palate lung nasal epithelial clone 1). A unique α-helix (α4) that extends from the body of SPLUNC1 is required for the bacteriostatic, surfactant, and LPS binding activities of this protein. Indeed, we find that mutation of just four leucine residues within this helical motif to alanine is sufficient to significantly inhibit the fluid spreading abilities of SPLUNC1, as well as its bacteriostatic actions against Gram-negative pathogens Burkholderia cenocepacia and Pseudomonas aeruginosa. Conformational flexibility in the body of SPLUNC1 is also involved in the bacteriostatic, surfactant, and LPS binding functions of the protein as revealed by disulfide mutants introduced into SPLUNC1. In addition, SPLUNC1 exerts antibiofilm effects against Gram-negative bacteria, although α4 is not involved in this activity. Interestingly, though, the introduction of surface electrostatic mutations away from α4 based on the unique dolphin SPLUNC1 sequence, and confirmed by crystal structure, is shown to impart antibiofilm activity against Staphylococcus aureus, the first SPLUNC1-dependent effect against a Gram-positive bacterium reported to date. Together, these data pinpoint SPLUNC1 structural motifs required for the antimicrobial and surfactant actions of this protective human protein.
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Affiliation(s)
- William G. Walton
- Departments of Chemistry, Biochemistry and Microbiology, 4350 Genome Sciences Building, University of North Carolina, Chapel Hill, NC 27599-3290, USA
| | - Saira Ahmad
- Marsico Lung Institute, Cystic Fibrosis/Pulmonary Research and Treatment Center, 7102 Marsico Hall, University of North Carolina, Chapel Hill, NC 27599-7248, USA
| | - Michael R. Little
- Departments of Chemistry, Biochemistry and Microbiology, 4350 Genome Sciences Building, University of North Carolina, Chapel Hill, NC 27599-3290, USA
| | - Christine S.K. Kim
- Marsico Lung Institute, Cystic Fibrosis/Pulmonary Research and Treatment Center, 7102 Marsico Hall, University of North Carolina, Chapel Hill, NC 27599-7248, USA
| | - Jean Tyrrell
- Marsico Lung Institute, Cystic Fibrosis/Pulmonary Research and Treatment Center, 7102 Marsico Hall, University of North Carolina, Chapel Hill, NC 27599-7248, USA
| | - Qiao Lin
- Department of Environmental and Occupational Health, 331 Bridgeside Point Building, University of Pittsburgh, Pittsburgh, PA 15260
| | - Y. Peter Di
- Department of Environmental and Occupational Health, 331 Bridgeside Point Building, University of Pittsburgh, Pittsburgh, PA 15260
| | - Robert Tarran
- Marsico Lung Institute, Cystic Fibrosis/Pulmonary Research and Treatment Center, 7102 Marsico Hall, University of North Carolina, Chapel Hill, NC 27599-7248, USA
| | - Matthew R. Redinbo
- Departments of Chemistry, Biochemistry and Microbiology, 4350 Genome Sciences Building, University of North Carolina, Chapel Hill, NC 27599-3290, USA,Corresponding Author: 4350 Genome Sciences Building, University of North Carolina, Chapel Hill, NC 27599-3290, USA, 919-962-4581, 919-962-2388 fax,
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5
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Saferali A, Obeidat M, Bérubé JC, Lamontagne M, Bossé Y, Laviolette M, Hao K, Nickle DC, Timens W, Sin DD, Postma DS, Strug LJ, Gallins PJ, Paré PD, Bingle CD, Sandford AJ. Polymorphisms associated with expression of BPIFA1/BPIFB1 and lung disease severity in cystic fibrosis. Am J Respir Cell Mol Biol 2016; 53:607-14. [PMID: 25574903 DOI: 10.1165/rcmb.2014-0182oc] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
BPI fold containing family A, member 1 (BPIFA1) and BPIFB1 are putative innate immune molecules expressed in the upper airways. Because of their hypothesized roles in airway defense, these molecules may contribute to lung disease severity in cystic fibrosis (CF). We interrogated BPIFA1/BPIFB1 single-nucleotide polymorphisms in data from an association study of CF modifier genes and found an association of the G allele of rs1078761 with increased lung disease severity (P = 2.71 × 10(-4)). We hypothesized that the G allele of rs1078761 is associated with decreased expression of BPIFA1 and/or BPIFB1. Genome-wide lung gene expression and genotyping data from 1,111 individuals with lung disease, including 51 patients with CF, were tested for associations between genotype and BPIFA1 and BPIFB1 gene expression levels. Findings were validated by quantitative PCR in a subset of 77 individuals. Western blotting was used to measure BPIFA1 and BPIFB1 protein levels in 93 lung and 101 saliva samples. The G allele of rs1078761 was significantly associated with decreased mRNA levels of BPIFA1 (P = 4.08 × 10(-15)) and BPIFB1 (P = 0.0314). These findings were confirmed with quantitative PCR and Western blotting. We conclude that the G allele of rs1078761 may be detrimental to lung function in CF owing to decreased levels of BPIFA1 and BPIFB1.
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Affiliation(s)
- Aabida Saferali
- 1 Centre for Heart Lung Innovation, UBC and St. Paul's Hospital, Vancouver, British Columbia
| | - Ma'en Obeidat
- 1 Centre for Heart Lung Innovation, UBC and St. Paul's Hospital, Vancouver, British Columbia
| | | | - Maxime Lamontagne
- 2 Institut Universitaire de Cardiologie et de Pneumologie de Québec and
| | - Yohan Bossé
- 2 Institut Universitaire de Cardiologie et de Pneumologie de Québec and.,3 Department of Molecular Medicine, Laval University, Québec, Quebec
| | - Michel Laviolette
- 2 Institut Universitaire de Cardiologie et de Pneumologie de Québec and
| | - Ke Hao
- 4 Icahn Institute of Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, New York
| | - David C Nickle
- 5 Merck Research Laboratories, Boston, Massachusetts.,6 Merck, Rahway, New Jersey.,7 Genetics, Rosetta Inpharmatics, Merck, Seattle, Washington
| | - Wim Timens
- Departments of 8 Pathology and Medical Biology and
| | - Don D Sin
- 1 Centre for Heart Lung Innovation, UBC and St. Paul's Hospital, Vancouver, British Columbia
| | - Dirkje S Postma
- 9 Pulmonary Medicine and Tuberculosis, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Lisa J Strug
- 10 Program in Genetics and Genome Biology, The Hospital For Sick Children, and Biostatistics Division, Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada
| | - Paul J Gallins
- 11 Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; and
| | - Peter D Paré
- 1 Centre for Heart Lung Innovation, UBC and St. Paul's Hospital, Vancouver, British Columbia
| | - Colin D Bingle
- 12 Academic Unit of Respiratory Medicine, Department of Infection and Immunity, University of Sheffield, Sheffield, United Kingdom
| | - Andrew J Sandford
- 1 Centre for Heart Lung Innovation, UBC and St. Paul's Hospital, Vancouver, British Columbia
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6
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Ning F, Wang C, Berry KZ, Kandasamy P, Liu H, Murphy RC, Voelker DR, Nho CW, Pan CH, Dai S, Niu L, Chu HW, Zhang G. Structural characterization of the pulmonary innate immune protein SPLUNC1 and identification of lipid ligands. FASEB J 2014; 28:5349-60. [PMID: 25223608 DOI: 10.1096/fj.14-259291] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The short palate, lung and nasal epithelial clone 1 (SPLUNC1) protein is a member of the palate, lung, and nasal epithelium clone (PLUNC) family, also known as bactericidal/permeability-increasing (BPI) fold-containing protein, family A, member 1 (BPIFA1). SPLUNC1 is an abundant protein in human airways, but its function remains poorly understood. The lipid ligands of SPLUNC1 as well as other PLUNC family members are largely unknown, although some reports provide evidence that lipopolysaccharide (LPS) could be a lipid ligand. Unlike previous hypotheses, we found significant structural differences between SPLUNC1 and BPI. Recombinant SPLUNC1 produced in HEK 293 cells harbored several molecular species of sphingomyelin and phosphatidylcholine as its ligands. Significantly, in vitro lipid-binding studies failed to demonstrate interactions between SPLUNC1 and LPS, lipoteichoic acid, or polymyxin B. Instead, one of the major and most important pulmonary surfactant phospholipids, dipalmitoylphosphatidylcholine (DPPC), bound to SPLUNC1 with high affinity and specificity. We found that SPLUNC1 could be the first protein receptor for DPPC. These discoveries provide insight into the specific determinants governing the interaction between SPLUNC1 and lipids and also shed light on novel functions that SPLUNC1 and other PLUNC family members perform in host defense.
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Affiliation(s)
- Fangkun Ning
- School of Life Sciences, University of Science and Technology of China, Hefei, China; Integrated Department of Immunology, National Jewish Health and University of Colorado Denver, Denver, Colorado, USA
| | - Chao Wang
- Integrated Department of Immunology, National Jewish Health and University of Colorado Denver, Denver, Colorado, USA
| | - Karin Zemski Berry
- Department of Pharmacology, University of Colorado Denver, Aurora, Colorado, USA
| | | | - Haolin Liu
- Integrated Department of Immunology, National Jewish Health and University of Colorado Denver, Denver, Colorado, USA
| | - Robert C Murphy
- Department of Pharmacology, University of Colorado Denver, Aurora, Colorado, USA
| | - Dennis R Voelker
- Department of Medicine, National Jewish Health, Denver, Colorado, USA; and
| | - Chu Won Nho
- Functional Food Center, Korea Institute of Science and Technology, GangNeung, Korea
| | - Choel-Ho Pan
- Functional Food Center, Korea Institute of Science and Technology, GangNeung, Korea
| | - Shaodong Dai
- Integrated Department of Immunology, National Jewish Health and University of Colorado Denver, Denver, Colorado, USA
| | - Liwen Niu
- School of Life Sciences, University of Science and Technology of China, Hefei, China;
| | - Hong-Wei Chu
- Integrated Department of Immunology, National Jewish Health and University of Colorado Denver, Denver, Colorado, USA; Department of Medicine, National Jewish Health, Denver, Colorado, USA; and
| | - Gongyi Zhang
- Integrated Department of Immunology, National Jewish Health and University of Colorado Denver, Denver, Colorado, USA
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7
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Di YP, Tkach AV, Yanamala N, Stanley S, Gao S, Shurin MR, Kisin ER, Kagan VE, Shvedova A. Dual acute proinflammatory and antifibrotic pulmonary effects of short palate, lung, and nasal epithelium clone-1 after exposure to carbon nanotubes. Am J Respir Cell Mol Biol 2013; 49:759-67. [PMID: 23721177 DOI: 10.1165/rcmb.2012-0435oc] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Carbon nanotubes (CNTs; allotropes of carbon with a cylindrical nanostructure) have emerged as one of the most commonly used types of nanomaterials, with numerous applications in industry and biomedicine. However, the inhalation of CNTs has been shown to elicit pulmonary toxicity, accompanied by a robust inflammatory response with an early-onset fibrotic phase. Epithelial host-defense proteins represent an important component of the pulmonary innate immune response to foreign inhalants such as particles and bacteria. The short palate, lung, and nasal epithelium clone-1 (SPLUNC1) protein, a member of the bactericidal/permeability-increasing-fold (BPIF)-containing protein family, is a 25-kD secretory protein that is expressed in nasal, oropharyngeal, and lung epithelia, and has been shown to have multiple functions, including antimicrobial and chemotactic activities, as well as surfactant properties. This study sought to assess the importance of SPLUNC1-mediated pulmonary responses in airway epithelial secretions, and to explore the biological relevance of SPLUNC1 to inhaled particles in a single-walled carbon nanotube (SWCNT) model. Using Scgb1a1-hSPLUNC1 transgenic mice, we observed that SPLUNC1 significantly modified host inflammatory responses by increasing leukocyte recruitment and enhancing phagocytic activity. Furthermore, we found that transgenic mice were more susceptible to SWCNT exposure at the acute phase, but showed resistance against lung fibrogenesis through pathological changes in the long term. The binding of SPLUNC1 also attenuated SWCNT-induced TNF-α secretion by RAW 264.7 macrophages. Taken together, our data indicate that SPLUNC1 is an important component of mucosal innate immune defense against pulmonary inhaled particles.
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Affiliation(s)
- Y Peter Di
- 1 Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, Pennsylvania
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Rowe SM, Reeves G, Hathorne H, Solomon GM, Abbi S, Renard D, Lock R, Zhou P, Danahay H, Clancy JP, Waltz DA. Reduced sodium transport with nasal administration of the prostasin inhibitor camostat in subjects with cystic fibrosis. Chest 2013; 144:200-207. [PMID: 23412700 DOI: 10.1378/chest.12-2431] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Prostasin, a trypsin-like serine protease, is a channel-activating protease and major regulator of epithelial sodium channel-mediated sodium absorption. Its direct inhibition by camostat represents a potential approach to inhibiting sodium transport in cystic fibrosis (CF). METHODS To determine whether a topical formulation of camostat represents an efficacious and tolerable approach to reducing Na+ transport in the CF airway, we conducted a two-part randomized, double-blind, placebo-controlled, crossover, ascending single-dose study to evaluate the pharmacodynamics, safety, and pharmacokinetics of camostat administered through a nasal spray pump in subjects with CF. Nasal potential difference (PD) was measured before and after treatment, and safety and pharmacokinetics were assessed by a standardized approach. RESULTS In part 1, nine subjects were enrolled, and six completed crossover dosing at the maximally tolerated dose. The change in maximal (most polarizing) basal PD 2 h following administration of camostat was +13.1 mV (1.6-mg dose group) compared with -8.6 mV following placebo (P<.005). Intrasubject change in Ringer and amiloride-sensitive PDs exhibited similar and consistent responses. Bayesian analysis in an additional six subjects in part 2 estimated a dose of 18 μg/mL to provide 50% of the maximum effect. There was no significant change in chloride transport or total nasal symptom score, nasal examination rating, and laboratory parameters. CONCLUSIONS This study establishes the proof of concept that a reduction in sodium transport in the human CF airway can be achieved through inhibition of prostasin activity, identifying a potential therapeutic target in the disease. TRIAL REGISTRATION ClinicalTrials.gov; No.: NCT00506792; URL: www.clinicaltrials.gov.
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Affiliation(s)
- Steven M Rowe
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL; Department of Pediatrics, University of Alabama at Birmingham, Birmingham, AL; Department of Physiology and Biophysics, University of Alabama at Birmingham, Birmingham, AL; Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, AL.
| | - Ginger Reeves
- Department of Pediatrics, University of Alabama at Birmingham, Birmingham, AL; Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, AL
| | - Heather Hathorne
- Department of Pediatrics, University of Alabama at Birmingham, Birmingham, AL; Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, AL
| | - G Martin Solomon
- Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, AL
| | - Smita Abbi
- Novartis Institutes for BioMedical Research, East Hanover, NJ
| | - Didier Renard
- Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Ruth Lock
- Novartis Institutes for BioMedical Research, Horsham, England
| | - Ping Zhou
- Novartis Institutes for BioMedical Research, Horsham, England
| | - Henry Danahay
- Novartis Institutes for BioMedical Research, Horsham, England
| | - John P Clancy
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, and University of Cincinnati, Cincinnati, OH
| | - David A Waltz
- Novartis Institutes for BioMedical Research, Cambridge, MA
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Jiang D, Wenzel SE, Wu Q, Bowler RP, Schnell C, Chu HW. Human neutrophil elastase degrades SPLUNC1 and impairs airway epithelial defense against bacteria. PLoS One 2013; 8:e64689. [PMID: 23741370 PMCID: PMC3669426 DOI: 10.1371/journal.pone.0064689] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 04/17/2013] [Indexed: 12/13/2022] Open
Abstract
Background Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) are a significant cause of mortality of COPD patients, and pose a huge burden on healthcare. One of the major causes of AECOPD is airway bacterial (e.g. nontypeable Haemophilus influenzae [NTHi]) infection. However, the mechanisms underlying bacterial infections during AECOPD remain poorly understood. As neutrophilic inflammation including increased release of human neutrophil elastase (HNE) is a salient feature of AECOPD, we hypothesized that HNE impairs airway epithelial defense against NTHi by degrading airway epithelial host defense proteins such as short palate, lung, and nasal epithelium clone 1 (SPLUNC1). Methodology/Main Results Recombinant human SPLUNC1 protein was incubated with HNE to confirm SPLUNC1 degradation by HNE. To determine if HNE-mediated impairment of host defense against NTHi was SPLUNC1-dependent, SPLUNC1 protein was added to HNE-treated primary normal human airway epithelial cells. The in vivo function of SPLUNC1 in NTHi defense was investigated by infecting SPLUNC1 knockout and wild-type mice intranasally with NTHi. We found that: (1) HNE directly increased NTHi load in human airway epithelial cells; (2) HNE degraded human SPLUNC1 protein; (3) Recombinant SPLUNC1 protein reduced NTHi levels in HNE-treated human airway epithelial cells; (4) NTHi levels in lungs of SPLUNC1 knockout mice were increased compared to wild-type mice; and (5) SPLUNC1 was reduced in lungs of COPD patients. Conclusions Our findings suggest that SPLUNC1 degradation by neutrophil elastase may increase airway susceptibility to bacterial infections. SPLUNC1 therapy likely attenuates bacterial infections during AECOPD.
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Affiliation(s)
- Di Jiang
- Department of Medicine, National Jewish Health, Denver, Colorado, United States of America
| | - Sally E. Wenzel
- Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Qun Wu
- Department of Medicine, National Jewish Health, Denver, Colorado, United States of America
| | - Russell P. Bowler
- Department of Medicine, National Jewish Health, Denver, Colorado, United States of America
| | - Christina Schnell
- Department of Medicine, National Jewish Health, Denver, Colorado, United States of America
| | - Hong Wei Chu
- Department of Medicine, National Jewish Health, Denver, Colorado, United States of America
- * E-mail:
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