Extracellular glutathione peroxidase in human lung epithelial
lining fluid and in lung cells.
Avissar, Nelly, Jacob N. Finkelstein, Stuart Horowitz, James C.
Willey, Erin Coy, Mark W. Frampton, Richard H. Watkins, Punam
Khullar, Yong-Ling Xu, and Harvey J. Cohen.
University of Rochester Medical Center, Departments of Pediatrics
and Medicine, Rochester, NY 14642, CardioPulmonary Research
Institute, Winthrop University Hospital, Mineola, NY 11501, Medical
College of Ohio, Department of Medicine, Toledo, OH 43699 and
Stanford University School of Medicine, Department of Pediatrics,
Palo Alto, CA 94305
APStracts 2:0165L, 1995.
The epithelial cells of the lower respiratory tract are exposed to
high levels of inhaled oxygen and other oxidants. We hypothesized
that lung cells would secrete the antioxidant enzyme, extracellular
glutathione peroxidase (eGPx), into epithelial lining fluid (ELF). To
investigate this hypothesis, we used specific immunoprecipitations of
GPx enzymes from ELF, specific immunoprecipitations of 75Se
metabolically labeled proteins from lung cells in culture, in situ
hybridization, Northern blot and reverse transcription polymerase
chain reaction (RT-PCR) analyses . 57% of ELF GPx activity was due to
eGPx and 40% was due to cellular GPx (cGPx). Primary bronchial
epithelial cells (BEC), primary alveolar macrophages (AM), and two
human bronchial epithelial cell lines, BEP2D and A549, synthesized
both eGPx and cGPx and secreted eGPx into the medium. Freshly
isolated human AM and BEC expressed eGPx mRNA, while freshly isolated
rabbit type 2 pneumocytes did not. In lung tissue, eGPx mRNA was
found mainly in interstitial cells of tissue surrounding airways. It
is concluded that more than half of GPx activity in BAL is due to
eGPx, and that BEC, AM, and interstitial cells are potential sources
of pulmonary eGPx.
Received 3 April 1995; accepted in final form 28 August 1995.
APS Manuscript Number L102-5.
Article publication pending Am. J. Physiol. (Lung Cell. Mol.
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 23 September 1995.