Analysis of mucus, mucin and DNA concentration, MUC5B/5AC ratio, rheology, osmotic pressure, cohesion and nucleotides in sputum on 30 individual samples of good quality in healthy individuals and those with bronchiectasis. (60 total)
In this study the investigators will investigate the mucus properties in individuals with idiopathic bronchiectasis and healthy individuals without a history of lung disease. In order to understand how mucus is abnormal in disease conditions, the investigators need to understand the mucus biochemical and biophysical properties in healthy individuals. In this study the investigators will prospectively recruit patients with bronchiectasis and healthy individuals from the community to provide airway sputum samples. In these samples the investigators will measure an array of mucus properties. This will help our understanding of the mucus-obstructive lung diseases and facilitate the development of appropriate and effective disease prevention strategies. A key question is whether mucus is hyper-concentrated and has abnormal biophysical properties in individuals with mucus-obstructive lung disease. To answer this question, the investigators need to understand the properties of the mucus in individuals with idiopathic bronchiectasis and no history of lung disease. This study will allow us to collect airway mucus (sputum) from individuals with bronchiectasis and healthy individuals with no history of lung disease.
Study Type
OBSERVATIONAL
Enrollment
30
Center for Environmental Medicine Asthma and Lung Biology
Chapel Hill, North Carolina, United States
Marsico Research Institure at Meadowmont
Chapel Hill, North Carolina, United States
Mucus concentration (% solids)
The percentage of solid content of sputum (an index of hydration) will be calculated my measuring the wet to dry weight ratio using a microbalance (mean percent solids ± standard deviation).
Time frame: 6 months
Biophysical properties of mucus by rheology
The rheological properties of the sputum will be assayed by macro-rheology (cone and plate) and microbead rheology. Macro-rheology provides measures of the viscosity (median log viscosity in Pascal (range)) and elasticity (median log elasticity in Pascal (range) of the sputum. Microbead rheology is performed by analyzing the diffusive motion of embedded 1μm tracer particles (6). The primary outcome measure from microbead rheology will be the mean square displacement MSD(Mean squared displacement) (median MSD cm2 s-1 (range)).
Time frame: 6 months
Mucin composition by mass spectroscopy
We will use mass spectroscopy to determine the relative abundance of the two major polymeric mucin proteins, MUC5B(Mucin type 5B)and MUC5AC(Mucin type 5AC), which are responsible for the viscoelastic properties of mucus.
Time frame: 6 months
Sputum extracellular nucleotide analysis
Sputum adenosine and adenine nucleotides will be ethenoderivatized and measured by HPLC(High performance liquid chromatography) analysis (7) (median nucleotide concentration in μg/ml (range)).
Time frame: 6 months
Osmotic Pressure
The osmotic pressure of the mucus will be assessed by placing an aliquot of mucus onto an osmometer with a 10kDa (10 kilodaltons) molecular weight polyethersulfone membrane (Millipore) separating the test chamber and reference chamber filled with PBS (phosphate-buffered saline) (mean osmotic pressure in Pascal ± standard deviation).
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Time frame: 6 months
Total mucin concentration
Mucins will be quantitated using sepharose CL2B(Cross-linked derivative of Sepharose 2B) UPLC(Ultra performance liquid chromatography) coupled to an Optilab interference refractometer with a filter at 680 nm and parallel flow chambers for solvent and the solution (mean mucin concentration (μg/ml) ± standard deviation) (4). With this approach, we will ensure that the solute is at full Donnan equilibrium with the solution within the context of gel chromatography, which creates an accurate equilibration of solute and solvent. This procedure also separates the mucins from contaminating proteins, allowing the mucins to be isolated for biochemical studies. DNAse can be added if significant DNA is present.
Time frame: 6 months
polymeric DNA concentration
The quantification of free DNA will be performed using the DNA Quant-iT PicoGreen assay (Molecular Probes, Inc., Eugene, OR, USA), which utilizes an ultra-sensitive fluorescent nucleic acid stain for quantitating double-stranded DNA (median log DNA concentration (μg/ml) (range)).
Time frame: 6 months