Amiloride Inhalation Therapy in Cystic Fibrosis: Influence on Ion Content, Hydration, and Rheology of Sputum

Tomkiewicz, R.P.; App, Ernst M.; Zayas, J. Gustavo; Ramírez, Óscar; Church, Nina L.; Boucher, Richard C.; Knowles, Michael R.; King, M.

doi:10.1164/ajrccm/148.4_pt_1.1002

Cited by 82 publications

(33 citation statements)

References 20 publications

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“…The role of epithelial Na ϩ channels in maintaining the middle ear cavities free of fluid (43,44) suggests that downregulation of Na ϩ channel activity may also underlie the known association between influenza infections and otitis media (11,45). Finally, our observation that influenza hemagglutinin inhibits Na ϩ channel activity may point the way to the development of a novel alternative to the use of Na ϩ channel blockers such as amiloride in the treatment of the Na ϩ channel overactivity seen in cystic fibrosis (46). …”

Section: ϫ2mentioning

confidence: 92%

Influenza virus inhibits amiloride-sensitive Na⁺channels in respiratory epithelia

Kunzelmann

Beesley

King

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

108

124

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Many pathogens causing diarrhea do so by modulating ion transport in the gut. Respiratory pathogens are similarly associated with disturbances of fluid balance in the respiratory tract, although it is not known whether they too act by altering epithelial ion transport. Here we show that influenza virus A͞PR͞8͞34 inhibits the amiloride-sensitive Na ؉ current across mouse tracheal epithelium with a half-time of about 60 min. We further show that the inhibitory effect of the influenza virus is caused by the binding of viral hemagglutinin to a cell-surface receptor, which then activates phospholipase C and protein kinase C. Given the importance of epithelial Na ؉ channels in controlling the amount of fluid in the respiratory tract, we suggest that down-regulation of Na ؉ channels induced by influenza virus may play a role in the fluid transport abnormalities that are associated with influenza infections.hemagglutinin ͉ protein kinase C ͉ ENaC ͉ phospholipase C

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Section: ϫ2mentioning

confidence: 92%

Influenza virus inhibits amiloride-sensitive Na⁺channels in respiratory epithelia

Kunzelmann

Beesley

King

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

108

124

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“…However, we estimated the percent dry weight (percentage of solids) of normal mucus at ϳ1.5-2.5% and of thick CF-like mucus at ϳ6 -15%, based on data reported from cell culture (26), a mouse model (4), and human studies (27)(28)(29)(30)(31)(32)(33). Mucus of 1.5% solids may be less than the normal optimal concentration because the network of mucin fibers and transport were heterogeneous (Fig.…”

Section: Figurementioning

confidence: 99%

“…1C), may reflect the concentration of mucins that occurs in larger airways due to increased mucin secretion and ASL volume absorption (36). The higher concentration of mucus we operationally chose to mimic CF, 6.5%, likely represents the minimum concentration found in CF airways before infection (29,30,32,33). Mucus transport assays demonstrated that 6.5% mucus was too thick to be transported by cilia, mimicking a key feature of CF mucus (2).…”

Section: Figurementioning

confidence: 99%

“…If the mucus is too thick for neutrophil penetration to kill bacteria and resolve infection, activated neutrophils trapped at the edges of thickened mucus masses could cause adverse effects. For example, neutrophil elastase, released during "frustrated phagocytosis," causes epithelial damage, Ig degradation, and mucus hypersecretion, all components of the uncontrolled inflammation that eventually leads to airway wall destruction (33,46).…”

Section: Figurementioning

confidence: 99%

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Reduced Three-Dimensional Motility in Dehydrated Airway Mucus Prevents Neutrophil Capture and Killing Bacteria on Airway Epithelial Surfaces

Matsui¹,

Verghese²,

Kesımer

et al. 2005

The Journal of Immunology

129

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Cystic fibrosis (CF) lung disease is characterized by persistent lung infection. Thickened (concentrated) mucus in the CF lung impairs airway mucus clearance, which initiates bacterial infection. However, airways have other mechanisms to prevent bacterial infection, including neutrophil-mediated killing. Therefore, we examined whether neutrophil motility and bacterial capture and killing functions are impaired in thickened mucus. Mucus of three concentrations, representative of the range of normal (1.5 and 2.5% dry weight) and CF-like thickened (6.5%) mucus, was obtained from well-differentiated human bronchial epithelial cultures and prepared for three-dimensional studies of neutrophil migration. Neutrophil chemotaxis in the direction of gravity was optimal in 1.5% mucus, whereas 2.5% mucus best supported neutrophil chemotaxis against gravity. Lateral chemokinetic movement was fastest on airway epithelial surfaces covered with 1.5% mucus. In contrast, neutrophils exhibited little motility in any direction in thickened (6.5%) mucus. In in vivo models of airway mucus plugs, neutrophil migration was inhibited by thickened mucus (CF model) but not by normal concentrations of mucus (“normal” model). Paralleling the decreased neutrophil motility in thickened mucus, bacterial capture and killing capacity were decreased in CF-like thickened mucus. Similar results with each mucus concentration were obtained with mucus from CF cultures, indicating that inhibition of neutrophil functions was mucus concentration dependent not CF source dependent. We conclude that concentrated (“thick”) mucus inhibits neutrophil migration and killing and is a key component in the failure of defense against chronic airways infection in CF.

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“…Although measurements of mucus concentration, i.e., the percentage of solids content, from CF subjects before infection have not been reported, estimates from cell cultures (11) and sputum (12)(13)(14)(15)(16)(17)(18) suggest that CF mucus is at least three or four times more concentrated than normal. Therefore, mucus was obtained from well differentiated human airway cultures and was isotonically concentrated (1) to produce mucus of normal (2.5% solids wt/wt) and CF-like (8%) concentrations (Fig.…”

mentioning

confidence: 99%

A physical linkage between cystic fibrosis airway surface dehydration and Pseudomonas aeruginosa biofilms

Matsui¹,

Wagner

Hill³

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

217

228

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A vexing problem in cystic fibrosis (CF) pathogenesis has been to explain the high prevalence of Pseudomonas aeruginosa biofilms in CF airways. We speculated that airway surface liquid (ASL) hyperabsorption generates a concentrated airway mucus that interacts with P. aeruginosa to promote biofilms. To model CF vs. normal airway infections, normal (2.5% solids) and CF-like concentrated (8% solids) mucus were prepared, placed in flat chambers, and infected with an Ϸ5 ؋ 10 3 strain PAO1 P. aeruginosa. Although bacteria grew to 10 10 cfu/ml in both mucus concentrations, macrocolony formation was detected only in the CF-like (8% solids) mucus. Biophysical and functional measurements revealed that concentrated mucus exhibited properties that restrict bacterial motility and small molecule diffusion, resulting in high local bacterial densities with high autoinducer concentrations. These properties also rendered secondary forms of antimicrobial defense, e.g., lactoferrin, ineffective in preventing biofilm formation in a CF-like mucus environment. These data link airway surface liquid hyperabsorption to the high incidence of P. aeruginosa biofilms in CF via changes in the hydration-dependent physical-chemical properties of mucus and suggest that the thickened mucus gel model will be useful to develop therapies of P. aeruginosa biofilms in CF airways.mucus ͉ rheology C ystic fibrosis (CF) lung disease reflects the chronic bacterial infection of intrapulmonary airways with Pseudomonas aeruginosa biofilms (1, 2). P. aeruginosa biofilms have mostly been studied in flow chambers (3-7) that are good models for the biofilms that form on venous or urethral catheters under conditions of high flow rates and relatively high oxygen tensions. However, biofilms in CF airways form in thickened (concentrated) mucus gels that are relatively hypoxic and adherent to airway surfaces (see Fig. 1A) (8, 9). Recently, Sriramulu et al. (10) investigated the role autoregulators and amino acids play in the tightness of biofilm formation in a mucus stimulant of constant hydration. For the present study, we designed a culture system to investigate whether dehydration of the CF mucus environment may predispose to P. aeruginosa biofilm formation.A key aspect of the model was the selection of mucus concentrations that mimic normal and CF mucus. Although measurements of mucus concentration, i.e., the percentage of solids content, from CF subjects before infection have not been reported, estimates from cell cultures (11) and sputum (12-18) suggest that CF mucus is at least three or four times more concentrated than normal. Therefore, mucus was obtained from well differentiated human airway cultures and was isotonically concentrated (1) to produce mucus of normal (2.5% solids wt/wt) and CF-like (8%) concentrations (Fig. 1B). Aliquots of each were deposited in (i) an open chamber to model a mucus plaque adherent to CF airway surfaces with a residual lumen allowing airflow and (ii) a closed chamber to mimic a mucus plug occluding a CF airway (Fig. 1 A). P....

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Amiloride Inhalation Therapy in Cystic Fibrosis: Influence on Ion Content, Hydration, and Rheology of Sputum

Cited by 82 publications

References 20 publications

Influenza virus inhibits amiloride-sensitive Na⁺channels in respiratory epithelia

Influenza virus inhibits amiloride-sensitive Na⁺channels in respiratory epithelia

Reduced Three-Dimensional Motility in Dehydrated Airway Mucus Prevents Neutrophil Capture and Killing Bacteria on Airway Epithelial Surfaces

A physical linkage between cystic fibrosis airway surface dehydration and Pseudomonas aeruginosa biofilms

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Amiloride Inhalation Therapy in Cystic Fibrosis: Influence on Ion Content, Hydration, and Rheology of Sputum

Cited by 82 publications

References 20 publications

Influenza virus inhibits amiloride-sensitive Na+channels in respiratory epithelia

Influenza virus inhibits amiloride-sensitive Na+channels in respiratory epithelia

Reduced Three-Dimensional Motility in Dehydrated Airway Mucus Prevents Neutrophil Capture and Killing Bacteria on Airway Epithelial Surfaces

A physical linkage between cystic fibrosis airway surface dehydration and Pseudomonas aeruginosa biofilms

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Product

Resources

About

Influenza virus inhibits amiloride-sensitive Na⁺channels in respiratory epithelia

Influenza virus inhibits amiloride-sensitive Na⁺channels in respiratory epithelia