Published ahead of print on September 29, 2005, doi:10.1165/rcmb.2005-0256OC Am. J. Respir. Cell Mol. Biol., Volume 34, Number 2, February 2006, 135-141 A more recent version of this article appeared on February 1, 2006
Submitted on July 11, 2005 Identification of Glycosaminoglycans in Human Airway SecretionsMaria E Monzon1,1 Department of Medicine, Division of Pulmonary and Critical Care Medicine, University of Miami School of Medicine, Miami, FL, USA * To whom correspondence should be addressed. E-mail: rforteza{at}miami.edu.
Glycosaminoglycans (GAGs), known to be present in airway mucus, are macromolecules with a variety of structural and biological functions. In the present work, we used fluorophore-assisted carbohydrate electrophoresis (FACE) to identify and relatively quantify GAGs in human tracheal aspirates (HTA) obtained from healthy volunteers. Primary cultures of normal human bronchial epithelial (NHBE) and submucosal glands (SMG) cells were used to assess their differential contribution to GAGs in mucus. Distribution was further assessed by immunofluorescence in human trachea tissue sections and in cell cultures. HTA samples contained keratan sulfate (KS), chondroitin/dermatan sulfate (CS/DS), and hyaluronan (HA) while heparan sulfate (HS) was not detected. SMG cultures secreted CS/DS and HA, CS/DS being the most abundant GAGs in these cultures. NHBE cells synthesized KS, HA, and CS/DS. Confocal microscopy showed that KS was exclusively found at the apical border of NHBE cells and on apical surface of ciliated epithelial cells in tracheal tissues. CS/DS and HA were present in both, NHBE and SMG cells. HS was only found in the extracellular matrix in trachea tissue sections. In summary, HTA samples contain KS, CS/DS, and HA, mirroring a mixture of secretions originated in surface epithelial cells and submucosal glands. We conclude that surface epithelium is responsible for most HA and all KS present in secretions while glands secrete most of CS/DS. These data suggest that in diseases where the contribution to secretions of glands vs. epithelial cells is altered, the relative concentration of individual GAGs, and therefore their biological activities, will also be affected.
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