Localization of extracellular superoxide dismutase in rat lung: neutrophils and macrophages as carriers of the enzyme.
Immunohistochemistry (IHC) and in situ hybridization (ISH) was used to localize extracellular superoxide dismutase (EC-SOD) and its mRNA in rat lung before and after a lipopolysaccharide (LPS)- and hyperoxia-induced inflammation. In control rats, EC-SOD mRNA was synthesized in macrophages and in cells of the arterial vessel walls and the alveolar septa. The EC-SOD protein was mainly localized in plasma and on the apical side of the epithelial cells located near bronchus-associated lymphoid tissue (BALT). ISH did not reveal major changes in the distribution of EC-SOD mRNA upon induction of inflammation. In contrast, IHC demonstrated a progressive staining of the epithelium of the larger bronchi for the protein. Neutrophils and macrophages invading the lung showed an intensive staining for the EC-SOD protein concomitantly with a decrease of the enzyme in the plasma. Twenty-four hours after LPS stimulation only a spotty positivity remained on neutrophils in and between the alveolar spaces. In the bronchoalveolar lavage fluid (BALF), only macrophages showed a strong positivity for EC-SOD mRNA while the protein was detected in macrophages and neutrophils. Exposure to hyperoxia did not affect the distribution of EC-SOD mRNA and protein. The presented data demonstrated that in lung tissue the EC-SOD enzyme may have a protective function for activated macrophages, neutrophils, and lympoid tissue-associated epithelial cells.
Loenders
B
B
Laboratory of Pharmacology, University of Antwerp (UIA), Antwerpen-Wilrijk, Belgium.
Van Mechelen
E
E
Nicolaï
S
S
Buyssens
N
N
Van Osselaer
N
N
Jorens
P G
PG
Willems
J
J
Herman
A G
AG
Slegers
H
H
D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D005110:Extracellular Space / Q000201:enzymology; D018496:Hyperoxia / Q000201:enzymology; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007249:Inflammation / Q000201:enzymology / Q000209:etiology / Q000473:pathology; D008070:Lipopolysaccharides / Q000633:toxicity; D008168:Lung / Q000166:cytology / Q000201:enzymology*; D016676:Macrophages, Alveolar / Q000201:enzymology; D008297:Male; D009504:Neutrophils / Q000201:enzymology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013482:Superoxide Dismutase / Q000097:blood / Q000235:genetics / Q000378:metabolism*
D008070:Lipopolysaccharides; D012333:RNA, Messenger; D013482:Superoxide Dismutase