Oxygen tension modulates differentiation and primary macrophage functions in the human monocytic THP-1 cell line.
The human THP-1 cell line is widely used as an in vitro model system for studying macrophage differentiation and function. Conventional culture conditions for these cells consist of ambient oxygen pressure (∼20% v/v) and medium supplemented with the thiol 2-mercaptoethanol (2-ME) and serum. In consideration of the redox activities of O₂ and 2-ME, and the extensive experimental evidence supporting a role for reactive oxygen species (ROS) in the differentiation and function of macrophages, we addressed the question of whether culturing THP-1 cells under a more physiologically relevant oxygen tension (5% O₂) in the absence of 2-ME and serum would alter THP-1 cell physiology. Comparisons of cultures maintained in 18% O₂versus 5% O₂ indicated that reducing oxygen tension had no effect on the proliferation of undifferentiated THP-1 cells. However, decreasing the oxygen tension to 5% O₂ significantly increased the rate of phorbol ester-induced differentiation of THP-1 cells into macrophage-like cells as well as the metabolic activity of both undifferentiated and PMA-differentiated THP-1 cells. Removal of both 2-ME and serum from the medium decreased the proliferation of undifferentiated THP-1 cells but increased metabolic activity and the rate of differentiation under either oxygen tension. In differentiated THP-1 cells, lowering the oxygen tension to 5% O₂ decreased phagocytic activity, the constitutive release of β-hexosaminidase and LPS-induced NF-κB activation but enhanced LPS-stimulated release of cytokines. Collectively, these data demonstrate that oxygen tension influences THP-1 cell differentiation and primary macrophage functions, and suggest that culturing these cells under tightly regulated oxygen tension in the absence of exogenous reducing agent and serum is likely to provide a physiologically relevant baseline from which to study the role of the local redox environment in regulating THP-1 cell physiology.
Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, California, United States of America.
Ana Cristina G
AC
Grodzki
Cecilia
C
Giulivi
Pamela J
PJ
Lein
D002273:Carcinogens / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects*; D002460:Cell Line; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000166:cytology / Q000378:metabolism*; D008623:Mercaptoethanol / Q000494:pharmacology; D016328:NF-kappa B / Q000378:metabolism; D010084:Oxidation-Reduction / Q000187:drug effects; D010100:Oxygen / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D002273:Carcinogens; D008070:Lipopolysaccharides; D016328:NF-kappa B; D017382:Reactive Oxygen Species; D008623:Mercaptoethanol; D013755:Tetradecanoylphorbol Acetate; D010100:Oxygen