Composition of sputum from patients with cystic fibrosis

Kilbourn, J.P.

doi:10.1007/bf01567570

Cited by 21 publications

(13 citation statements)

References 12 publications

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“…Levels of specific components, including sodium, chloride, potassium, calcium, ammonium, and magnesium resemble those previously reported (13,21,24,48,49). Although concentrations of individual amino acids, glucose, and lactate have not previously been reported for CF sputum, the total free amino acid concentrations measured in this study are comparable to those previously published by Thomas et al (59).…”

Section: Discussionsupporting

confidence: 89%

Nutritional Cues ControlPseudomonas aeruginosaMulticellular Behavior in Cystic Fibrosis Sputum

2007

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The sputum (mucus) layer of the cystic fibrosis (CF) lung is a complex substrate that provides Pseudomonas aeruginosa with carbon and energy to support high-density growth during chronic colonization. Unfortunately, the CF lung sputum layer has been difficult to mimic in animal models of CF disease, and mechanistic studies of P. aeruginosa physiology during growth in CF sputum are hampered by its complexity. In this study, we performed chromatographic and enzymatic analyses of CF sputum to develop a defined, synthetic CF sputum medium (SCFM) that mimics the nutritional composition of CF sputum. Importantly, P. aeruginosa displays similar phenotypes during growth in CF sputum and in SCFM, including similar growth rates, gene expression profiles, carbon substrate preferences, and cell-cell signaling profiles. Using SCFM, we provide evidence that aromatic amino acids serve as nutritional cues that influence cell-cell signaling and antimicrobial activity of P. aeruginosa during growth in CF sputum.A key concept in bacterial pathogenesis is the ability of invading pathogens to obtain sufficient carbon and energy from the host for in vivo growth. Although Garber originally proposed the host as a growth medium over 40 years ago (12), the nutritional environment of most infection sites is poorly defined and often inadequately modeled by laboratory growth media. This lack of knowledge, combined with the limited utility of many animal models, provides significant challenges for mechanistic studies aimed at examining host nutrients as mediators of colonization and disease. To overcome these challenges, it is critical both to define the nutritional composition of key infection sites and to study bacterial physiology in the context of in vivo-relevant growth substrates.The heritable disease cystic fibrosis (CF) is an archetype for the development of nutritional models with which to study bacterial pathogenesis. A hallmark of CF disease is the accumulation of large volumes of sputum (mucus) within the lungs, which diminishes the host's ability to clear bacterial infections (17,31). The viscous CF lung sputum provides bacteria with a nutritionally rich growth environment composed of host-and bacterial-derived factors (17, 38). The opportunistic pathogen Pseudomonas aeruginosa chronically colonizes the CF lung, where it often grows to high cell densities in CF sputum (Ͼ10 9 cells/ml sputum). Although many other bacterial species persist and grow in the CF lung, chronic P. aeruginosa infection is likely the most clinically relevant, as it is correlated with declining lung function (17). Mechanistically, P. aeruginosa colonization and progression to chronic infection is poorly understood, although potential contributing factors are high-density growth and enhanced fitness of P. aeruginosa in CF sputum. P. aeruginosa fitness has been linked to nutritional components in CF sputum (39), thus necessitating the development of a versatile model that allows examination of CF sputum nutritional cues.The growth environment impacts several...

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Section: Discussionsupporting

confidence: 89%

Nutritional Cues ControlPseudomonas aeruginosaMulticellular Behavior in Cystic Fibrosis Sputum

2007

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“…Kilbourn (1984) reported that the concentration of Ca2+ in sputum specimens from CF patients is high (range of 0.1 to 4.4 mM 1-') and suggested an association between Ca2+ and colonization by staphylococci. Results from the present study show that the presence of Ca2+ actually enhances the adhesion of S. aureus, as well as S. epidermidis, to mucin (one of the components of sputum) (Figs 1 and 2) and, further, that the enhanced adhesion is specific for Ca2+ (Fig.…”

Section: Discussionmentioning

confidence: 99%

Calcium- and Mucin-Binding Proteins of Staphylococci

Thomas

Sanford

Ramsay

1993

Journal of General Microbiology

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The association of staphylococci with the mucus gel that overlays the mucosa of the respiratory tract may lead to clearance of cocci or, in certain conditions such as cystic fibrosis (CF), to colonization. In the present study, a quantitative radioassay was used to study the effect of Ca2+, which is elevated in CF sputa, on the adhesion of 3H-labelled Staphylococcus aureus to submaxillary gland much immobilized in MaxiSorp 96-well, break-apart modules. Ca2+ significantly enhanced the adhesion of S. aureus (five strains) and Staphylococcus epidermidis (four strains). The reaction was specific because adhesion was not enhanced in the presence of Mg2+, Ca2+ + EGTA (a Ca" chelator) or protamine and was not attributable to hydrophobicity of the test strains. Staphylococcal adhesion was significantly (P d 0.005) blocked in the presence of highly sialated and sulphated reagents, which suggests that Ca" binds to the sialic acid and sulphate residues of immobilized mucin. The Ca2+-binding sites on the surface of S. aureus were trypsin-sensitive ; in addition, 12%labelled solubilized S. aureus surface proteins reacted with immobilized mucin in a direct binding assay, and the reaction was significantly enhanced by Ca2+. Autoradiography demonstrated that 45Ca bound directly to two polypeptides (M, 170000 and 150000) of solubilized staphylococcal surface proteins separated by SDS-PAGE, and that '251-labelled mucin bound directly to three staphylococcal polypeptides (M, 40000,35000, and 29000). These results suggest that S. aureus adhesion to mucin is mediated by at least two mechanisms: via Ca2+-binding surface proteins in the presence of Ca2+ and via mucin-binding surface proteins unrelated to Ca2+.

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“…The amount of (free) Mg 2ϩ in the healthy human mucosa of the respiratory tract is largely unknown. Sputa of patients suffering from cystic fibrosis have been reported to contain approximately between 0.1 mM and 1 mM Mg 2ϩ , depending on the method used for measuring (13,27); the sputa of patients suffering from other bronchopneumopathologies were reported to contain around 0.5 mM Mg 2ϩ (13). Mutants in Mg 2ϩ homeostasis genes in a wide variety of pathogenic bacteria are attenuated for virulence (10,16,18,36,45).…”

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confidence: 99%

Deletion of a Cation Transporter Promotes Lysis in Streptococcus pneumoniae

et al. 2011

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Streptococcus pneumoniae is a significant human pathogen which causes respiratory and serious invasive diseases. Mg 2؉ is essential for life, and its concentration varies throughout the human body. Magnesium uptake plays an important role in the virulence of many bacterial pathogens. To study the Mg 2؉ uptake of S. pneumoniae strain D39, a mutant was generated in SPD1383, a P-type ATPase with homology to the Salmonella Mg 2؉ transporter MgtA, which has also been shown to be a Ca 2؉ exporter in strain TIGR4. Under low-Ca 2؉ conditions, mutation led to a growth defect in complex medium and the gene was nearly essential for growth under low-Mg 2؉ conditions. Addition of Mg 2؉ restored the normal growth of the mutant in all cases, but the addition of other divalent cations had no effect. Addition of Ca 2؉ , Mn 2؉ , and Zn 2؉ in the presence of high Mg 2؉ concentrations inhibited restoration of growth. The mutant was unable to proliferate in blood, which was also alleviated by the addition of Mg 2؉ . The protein was located in the membrane and produced in various S. pneumoniae strains and pathogenic streptococcal species. Surprisingly, mutation of the gene led to an elevated toxicity for endothelial cells. This was caused by an increased amount of pneumolysin in the medium, mediated by elevated lysis of the mutant. Thus, in this study, we uncovered a role for SPD1383 in Mg 2؉ uptake and hypothesize that the protein is a Mg 2؉/ Ca 2؉ antiporter. Furthermore, a disturbance in Mg 2؉ homeostasis seems to promote lysis of S. pneumoniae.

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Composition of sputum from patients with cystic fibrosis

Cited by 21 publications

References 12 publications

Nutritional Cues ControlPseudomonas aeruginosaMulticellular Behavior in Cystic Fibrosis Sputum

Nutritional Cues ControlPseudomonas aeruginosaMulticellular Behavior in Cystic Fibrosis Sputum

Calcium- and Mucin-Binding Proteins of Staphylococci

Deletion of a Cation Transporter Promotes Lysis in Streptococcus pneumoniae

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