AJP - Lung Cellular and Molecular Physiology, Vol 273, Issue 5 1073-L1081, Copyright © 1997 by American Physiological Society
Rat alveolar macrophages express preprotachykinin gene-I mRNA-encoding tachykinins
C. R. Killingsworth, S. A. Shore, F. Alessandrini, R. D. Dey and J. D. Paulauskis
Physiology Program, Harvard School of Public Health, Boston, Massachusetts 02115, USA.
Although the tachykinins substance P (SP) and neurokinin A have been
largely localized to neurons, eosinophils have also been shown to express
these peptides. Our aim was to determine whether rat alveolar macrophages
(AM) express preprotachykinin gene-I (PPT-I) mRNA that encodes these
tachykinins and to examine expression during inflammation. PPT-I mRNA was
detected by reverse transcription (RT)-polymerase chain reaction (PCR) in
AM and brain (control) but not in peritoneal macrophages. Northern analysis
showed that PPT-I mRNA was induced two- to fourfold by in vivo treatment of
rats with intratracheal lipopolysaccharide (LPS) and in vitro after 4 h of
exposure to LPS. This increase was inhibited by dexamethasone. In situ
RT-PCR and immunocytochemistry further confirmed that AM express PPT-I mRNA
and SP-like immunoreactivity, respectively, which was enhanced by LPS
treatment. A 1.3-kb transcript consistent with PPT-I mRNA was detected by
Northern analysis of bronchoalveolar lavage neutrophils. Therefore, rat AM
express PPT-I mRNA that is upregulated in AM by LPS and is attenuated by
dexamethasone. PPT-I mRNA was also detected in lung neutrophils.
