Tetraspanin CD9 negatively regulates lipopolysaccharide-induced macrophage activation and lung inflammation.
Tetraspanins facilitate the formation of multiple molecular complexes at specialized membrane microdomains and regulate cell activation and motility. In the present study, the role of tetraspanin CD9 in LPS-induced macrophage activation and lung inflammation was investigated in vitro and in vivo. When CD9 function was ablated with mAb treatment, small interfering RNA transfection, or gene knockout in RAW264.7 cells or bone marrow-derived macrophages, these macrophages produced larger amounts of TNF-alpha, matrix metalloproteinase-2, and -9 upon stimulation with LPS in vitro, when compared with control cells. Sucrose gradient analysis revealed that CD9 partly colocalized with the LPS-induced signaling mediator, CD14, at low-density light membrane fractions. In CD9 knockout macrophages, CD14 expression, CD14 and TLR4 localization into the lipid raft, and their complex formation were increased whereas IkappaBalpha expression was decreased when compared with wild-type cells, suggesting that CD9 prevents the formation of LPS receptor complex. Finally, deletion of CD9 in mice enhanced macrophage infiltration and TNF-alpha production in the lung after intranasal administration of LPS in vivo, when compared with wild-type mice. These results suggest that macrophage CD9 negatively regulates LPS response at lipid-enriched membrane microdomains.
Department of Respiratory Medicine, Allergy and Rheumatic Diseases, Osaka University Graduate School of Medicine, Osaka, Japan.
Mayumi
M
Suzuki
Isao
I
Tachibana
Yoshito
Y
Takeda
Ping
P
He
Seigo
S
Minami
Takeo
T
Iwasaki
Hiroshi
H
Kida
Sho
S
Goya
Takashi
T
Kijima
Mitsuhiro
M
Yoshida
Toru
T
Kumagai
Tadashi
T
Osaki
Ichiro
I
Kawase
D000818:Animals; D015703:Antigens, CD / Q000096:biosynthesis / Q000276:immunology* / Q000378:metabolism; D015153:Blotting, Western; D002460:Cell Line; D004797:Enzyme-Linked Immunosorbent Assay; D047468:Immunoprecipitation; D018950:Lipopolysaccharide Receptors / Q000096:biosynthesis / Q000276:immunology; D008070:Lipopolysaccharides / Q000276:immunology*; D008262:Macrophage Activation / Q000276:immunology*; D008264:Macrophages / Q000276:immunology / Q000378:metabolism; D020782:Matrix Metalloproteinases / Q000096:biosynthesis / Q000276:immunology; D008562:Membrane Glycoproteins / Q000276:immunology* / Q000378:metabolism; D021962:Membrane Microdomains / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D011014:Pneumonia / Q000276:immunology* / Q000378:metabolism; D034741:RNA, Small Interfering; D020133:Reverse Transcriptase Polymerase Chain Reaction; D060225:Tetraspanin 28; D060245:Tetraspanin 29; D051197:Toll-Like Receptor 4 / Q000276:immunology / Q000378:metabolism; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000276:immunology
D015703:Antigens, CD; C554799:Cd81 protein, mouse; C554870:Cd9 protein, mouse; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D034741:RNA, Small Interfering; D060225:Tetraspanin 28; D060245:Tetraspanin 29; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; D014409:Tumor Necrosis Factor-alpha; D020782:Matrix Metalloproteinases