Rat alveolar macrophages express preprotachykinin gene-I mRNA-encoding tachykinins.
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.
Killingsworth
C R
CR
Physiology Program, Harvard School of Public Health, Boston, Massachusetts 02115, USA.
Shore
S A
SA
Alessandrini
F
F
Dey
R D
RD
Paulauskis
J D
JD
D000818:Animals; D001921:Brain / Q000378:metabolism; D002478:Cells, Cultured; D003907:Dexamethasone; D007249:Inflammation; D008070:Lipopolysaccharides / Q000494:pharmacology; D008168:Lung / Q000503:physiopathology; D016676:Macrophages, Alveolar / Q000378:metabolism*; D015345:Oligonucleotide Probes; D016133:Polymerase Chain Reaction; D011498:Protein Precursors / Q000096:biosynthesis* / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015320:Tachykinins / Q000096:biosynthesis* / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects
D008070:Lipopolysaccharides; D015345:Oligonucleotide Probes; D011498:Protein Precursors; D012333:RNA, Messenger; D015320:Tachykinins; C044206:preprotachykinin; D003907:Dexamethasone