Abstract
Tetraspanins organize protein complexes in tetraspanin-enriched membrane microdomains that are distinct from lipid rafts. Our previous studies suggested that reduction in the levels of tetraspanins CD9 and CD81 may be involved in the progression of inflammatory lung diseases, especially COPD. To search for agents that increase the levels of these tetraspanins, we screened 1,165 drugs in clinical use and found that statins upregulate CD9 and CD81 in RAW264.7 macrophages. The lipophilic statins, fluvastatin and simvastatin, reversed LPS-induced downregulation of CD9 and CD81, simultaneously preventing TNF-α and matrix metalloproteinase-9 production and spreading of RAW264.7 cells. These statins exerted anti-inflammatory effects in vitro in wild-type macrophages but not in CD9 knockout macrophages, and decreased lung inflammation in vivo in wild-type mice but not in CD9 knockout mice, suggesting that their effects are dependent on CD9. Mechanistically, the statins promoted reverse transfer of the LPS-signaling mediator CD14 from lipid rafts into CD9-enriched microdomains, thereby preventing LPS receptor formation. Finally, upregulation of CD9/CD81 by statins was related to blockade of GTPase geranylgeranylation in the mevalonate pathway. Our data underscore the importance of the negative regulator CD9 in lung inflammation, and suggest that statins exert anti-inflammatory effects by upregulating tetraspanin CD9 in macrophages.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Blotting, Western
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Cell Line
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Cell Line, Tumor
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Cells, Cultured
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Drug Evaluation, Preclinical
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Fatty Acids, Monounsaturated / pharmacology
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Fluvastatin
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Hydroxymethylglutaryl-CoA Reductase Inhibitors / pharmacology*
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Indoles / pharmacology
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Lipopolysaccharide Receptors / metabolism
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Lipopolysaccharides / pharmacology
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Macrophages / drug effects*
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Macrophages / metabolism
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Matrix Metalloproteinase 9 / metabolism
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Membrane Microdomains / metabolism
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Mice
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Mice, Inbred C57BL
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Mice, Knockout
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NIH 3T3 Cells
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Pneumonia / genetics
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Pneumonia / metabolism
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Pneumonia / prevention & control*
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Protein Transport / drug effects
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Reverse Transcriptase Polymerase Chain Reaction
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Simvastatin / pharmacology
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Tetraspanin 28 / genetics
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Tetraspanin 28 / metabolism
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Tetraspanin 29 / genetics
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Tetraspanin 29 / metabolism*
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Tumor Necrosis Factor-alpha / metabolism
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Up-Regulation / drug effects
Substances
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Fatty Acids, Monounsaturated
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Hydroxymethylglutaryl-CoA Reductase Inhibitors
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Indoles
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Lipopolysaccharide Receptors
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Lipopolysaccharides
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Tetraspanin 28
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Tetraspanin 29
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Tumor Necrosis Factor-alpha
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Fluvastatin
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Simvastatin
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Matrix Metalloproteinase 9
Grants and funding
This work was supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology; a Health and Labour Sciences Research Grant from the Ministry of Health, Labour and Welfare; a grant from “Kansai Biomedical Cluster” project in Saito, which is promoted by the Knowledge Cluster Initiative of the Ministry of Education, Culture, Sports, Science and Technology, Japan (to IT); and the Funding Program for Next Generation World-Leading Researchers (NEXT Program) and Special Coordination Funds for Promoting Science and Technology (to AK). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.