Expression of scavenger receptor class A and CD14 in lipopolysaccharide-induced lung injury.
CD14 and macrophage scavenger receptor class A type I and II (MSR-A) are receptors for lipopolysaccharide (LPS). In this study, the expressions of both receptors in the lung after administration of LPS in aerosol to mice with a nebulizer were observed. Bronchiolar epithelial cells and alveolar macrophages immediately incorporated LPS and expressed CD14. CD14-positive neutrophils then appeared in the alveolar space followed by the appearance of MSR-A-expressing cells in the vascular lumen, pulmonary interstitium, and alveolar space. Numbers of apoptotic cells increased after 1 day, and MSR-A-expressing macrophages actively incorporated apoptotic bodies. Daily administration of macrophage colony stimulating factor (M-CSF) to the mice resulted in increased levels of MSR-A expression and reduced levels of CD14 as well as several cytokine expressions, leading to shortening of the inflammatory process. The numbers of apoptotic cells were reduced in M-CSF injected mice. These findings imply that CD14 acts as an immediate expressing receptor for LPS and MSR-A exerts a protective function by scavenging LPS and apoptotic cells in LPS-induced lung injury.
Yamamoto
T
T
Second Department of Pathology, Niigata University School of Medicine, Japan.
Ebe
Y
Y
Hasegawa
G
G
Kataoka
M
M
Yamamoto
S
S
Naito
M
M
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D015152:Blotting, Northern; D001992:Bronchoalveolar Lavage Fluid; D002452:Cell Count; D017931:DNA Primers / Q000737:chemistry; D005260:Female; D006651:Histocytochemistry; D007124:Immunoenzyme Techniques; D018950:Lipopolysaccharide Receptors / Q000096:biosynthesis* / Q000235:genetics; D008070:Lipopolysaccharides / Q000633:toxicity*; D008171:Lung Diseases / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D016173:Macrophage Colony-Stimulating Factor / Q000502:physiology; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D012333:RNA, Messenger / Q000378:metabolism; D011971:Receptors, Immunologic / Q000096:biosynthesis* / Q000235:genetics; D051116:Receptors, Scavenger; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051117:Scavenger Receptors, Class A
D017931:DNA Primers; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; C495140:Msr1 protein, mouse; D012333:RNA, Messenger; D011971:Receptors, Immunologic; D051116:Receptors, Scavenger; D051117:Scavenger Receptors, Class A; D016173:Macrophage Colony-Stimulating Factor