Cyclooxygenase isoenzyme localization and mRNA expression in rat lungs.
Prostanoid generation may proceed via both isoforms of cyclooxygenase, Cox-1 and Cox-2. Cox-1 is thought to be ubiquitously expressed, whereas Cox-2 is mostly assumed to be dynamically regulated, responding to inflammatory stimuli. The cellular localization of Cox-1 and Cox-2 in the lung, an organ with high cyclooxygenase activity, is not known. In normal rat lungs the expression and localization of Cox-1 and Cox-2 were examined with immunogold-silver staining and the RT-PCR technique. Quantitative image analysis of the staining intensity was performed by measuring mean gray values of digitized epipolarization images. Expression of both Cox-1 and Cox-2 was readily detectable in rat lungs. Cox-1 immunoreactivity localized predominantly to bronchial epithelial cells, smooth muscle cells of large hilum veins, and (with lower expression) to alveolar macrophages and pulmonary artery endothelial cells. The most intense Cox-2 staining was noted in macrophage- and mast cell-like cells, detected in close vicinity to the bronchial epithelium and in the connective tissue surrounding the vessels. In addition, strong Cox-2 expression was found in smooth muscle cells of partially muscular vessels and large veins of the hilum. Bronchial epithelial cells displayed Cox-2 immunoreactivity with limited intensity. Alveolar macrophages and alveolar septal cells were only occasionally stained with anti-Cox-2 antibodies. Both Cox-1 and Cox-2 are constitutively expressed in several cell types of normal rat lung, but display clearly different patterns of cellular localization. Cox-2 may not be related only to lung inflammation, but is suggested to be implicated in regulatory processes under physiological conditions as well.
Ermert
L
L
Department of Pathology, Justus-Liebig-University Giessen, Giessen, Germany. leander.ermert@anatomie.med.uni-giessen.de
Ermert
M
M
Goppelt-Struebe
M
M
Walmrath
D
D
Grimminger
F
F
Steudel
W
W
Ghofrani
H A
HA
Homberger
C
C
Duncker
H
H
Seeger
W
W
D000818:Animals; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D015870:Gene Expression / Q000235:genetics; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000032:analysis* / Q000235:genetics*; D008168:Lung / Q000737:chemistry / Q000201:enzymology*; D008297:Male; D008565:Membrane Proteins; D016133:Polymerase Chain Reaction / Q000379:methods; D011451:Prostaglandin-Endoperoxide Synthases / Q000032:analysis* / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D012194:RNA-Directed DNA Polymerase; D051381:Rats; D017207:Rats, Sprague-Dawley
D007527:Isoenzymes; D008565:Membrane Proteins; D012333:RNA, Messenger; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; C496513:Ptgs1 protein, rat; D012194:RNA-Directed DNA Polymerase