Composition of human airway mucins and effects after inhalation of
acid aerosol.
Culp, David J., Lisa R. Latchney, Mark W. Frampton, Marianne R.
Jahnke, Paul E. Morrow, and Mark J. Utell.
Departments of Dental Research and Medicine, University of
Rochester School of Medicine and Dentistry, Rochester, New York
14642
APStracts 2:0078L, 1995.
Characterization of normal airway mucus is required to elucidate
mechanisms protecting the airways and to understand changes
associated with disease and environmental insult. Towards this goal,
we collected bronchial washes (10 ml saline) from healthy human
subjects to 1) evaluate the yield of high-density material ([delta]
>/=1.35 g/ml), and 2) characterize glycoconjugates associated with
collected secretions. Samples were lipid extracted followed by CsCl
density gradient centrifugation. The yield of high-density material
from individual subjects was variable but sufficient to demonstrate
that mucin glycoproteins are a major constituent of mucus from
healthy airways and that proteoglycans are absent. Next, we
investigated whether inhalation of H2SO4 aerosol (1,000 [mu]g/m3), an
environmental insult associated with alterations in mucociliary
clearance, changes the composition of high-density glycoproteins in
airway secretions. In a paired, double blinded study, high-density
fractions of bronchial secretions from 12 subjects were collected 18
hrs after exposures of 2 hrs to aerosolized NaCl and H2SO4. In all
cases the high-density material displayed characteristics of mucin
glycoproteins. In addition, a unique 150 kDa glycoprotein was
detected in most but not all samples and may represent a small mucin
glycoprotein differentially expressed in man. No differences were
noted between the two exposure conditions in the profiles of the
glycoproteins or proteins after SDS-PAGE. Statistically, large
changes with acid exposure in the composition of carbohydrates and
amino acids were absent. Thus, no substantial systematic changes in
airway mucin glycoproteins or closely associated proteins and
glycoproteins were correlated with H2SO4 exposure. Alternatively,
statistical analysis of the differences between exposures in
glycoprotein constituents among subjects denoted greater variability
in carbohydrates compared to amino acids with repeated sampling,
suggesting normal daily variations in the mucin composition of
individual airway mucus.
Received 9 September 1994; accepted in final form 2 May 1995.
APS Manuscript Number L268-4.
Article publication pending Am. J. Physiol. (Lung Cell. Mol.
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 9 May 1995.