Am. J. Respir. Cell Mol. Biol., Vol 10, No. 6, 06 1994, 625-634.
Hypertrophic and hyperplastic changes of mucus-secreting epithelial cells in rat airways: assessment using a novel, rapid, and simple technique
DJ Pon, CJ van Staden and IW Rodger
Merck Frosst Centre for Therapeutic Research, Kirkland, Quebec, Canada.
Determination of hyperplastic and hypertrophic changes of mucus- secreting
cells in animal airways has been performed in the past by using histologic,
immunologic, and/or molecular biologic approaches. Histologic techniques
are tedious and time-consuming. The other approaches require specific
antibodies and cDNA probes that have proved difficult to develop. Described
here is a method for the rapid estimation of hyperplastic and hypertrophic
changes of secretory epithelial cells in rat airways. The assay
specifically measures acidic and neutral mucoproteins in a linear fashion
from 0.5 microgram to at least 10 micrograms. Male Sprague-Dawley rats were
exposed to metabisulfite mist (10% wt/vol) for 5 days/wk for 3 wk. The
lungs were removed and homogenized in a phosphate-buffered solution
containing reducing agents and protease inhibitors. The particulate matter
was removed by centrifugation, and the soluble extract was applied to a
column packed with Sepharose CL-6B. The material eluting in the void volume
was applied to a PVDF membrane and stained for either acidic or neutral
mucosubstances using Alcian blue or periodic acid-Schiff (PAS) staining,
and the absorbance was read using a 96-well plate reader. Lungs from sodium
metabisulfite-exposed animals showed a 7-fold and 3.5- fold increase in
PAS-positive and Alcian blue-positive material, respectively. The increase
in both PAS and Alcian blue staining was hyaluronidase and chondroitinase
insensitive. The observed changes are consistent with morphometric
measurements of mucus-containing cells in histologic sections of the
tissues. This assay may be useful in determining which neurohumoral
mediators might be involved in mucus cell hypertrophy and hyperplasia in
animal models of chronic obstructive pulmonary disease.