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Pace J, Lowenstein C, Phillips T, Chen L, Morrison D, Hunt J, Russell S. Population dynamics of inducible nitric oxide synthase production by LPSand LPS/IFNγ-stimulated mouse macrophages. ACTA ACUST UNITED AC 2016. [DOI: 10.1177/096805199400100404] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The reactive nitrogen intermediate, nitric oxide (NO) is important in host defense against both NO-sensitive microorganisms and tumor cells. Macrophages are one of the chief inflammatory sources, especially when stimulated with the combination of LPS and interferonγ (IFNγ). It is not known, however, whether IFNγ-mediated augmentation of LPS-induced production of NO is the result of greater production by all cells or to the recruitment of more producer macrophages within a given population. This question was addressed, first, by stimulating mouse macrophages (either bone marrow culture-derived, inflammatory peritoneal or those of the cell line, RAW 264.7) with up to 10 U/ml IFNγ for as long as 24 h. Under these conditions, there was little or no production of NO and rare or no cells were immunocytochemically positive for the inducible form of nitric oxide synthase (iNOS), which catalyzes the production of NO. Populations similarly exposed to 1 ng/ml LPS were low producers of NO and contained somewhat more, but still only a few (< 15%), iNOS-positive cells. In contrast, as the concentration of IFNγ was increased (≥ 1 U/ml) in the presence of a constant amount of LPS (1 ng/ml), the principal effect was to increase both the production of NO and the number of iNOS-positive macrophages. The amount of iNOS expressed by some cells also appeared to be increased. Two important conclusions can be drawn from these findings: (1) there is heterogeneity in mouse macrophage populations with respect to the production of iNOS; and (2) increasing concentrations of IFNγ appear to augment LPS-induced secretion of NO by recruiting increasingly greater numbers of macrophages into the production of iNOS. Such results potentially provide important clues as to how IFNγ may be acting at the subcellular level to enhance iNOS synthesis.
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Affiliation(s)
- J.L. Pace
- The University of Kansas Cancer Center and the Departments of Pathology/Laboratory Medicine, Microbiology/Molecular Genetics/Immunology, and Anatomy/Cell Biology, University of Kansas Medical Center, Kansas City, KS, USA, Division of Cardiology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - C.J. Lowenstein
- The University of Kansas Cancer Center and the Departments of Pathology/Laboratory Medicine, Microbiology/Molecular Genetics/Immunology, and Anatomy/Cell Biology, University of Kansas Medical Center, Kansas City, KS, USA, Division of Cardiology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - T.A. Phillips
- The University of Kansas Cancer Center and the Departments of Pathology/Laboratory Medicine, Microbiology/Molecular Genetics/Immunology, and Anatomy/Cell Biology, University of Kansas Medical Center, Kansas City, KS, USA, Division of Cardiology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - L.C. Chen
- The University of Kansas Cancer Center and the Departments of Pathology/Laboratory Medicine, Microbiology/Molecular Genetics/Immunology, and Anatomy/Cell Biology, University of Kansas Medical Center, Kansas City, KS, USA, Division of Cardiology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - D.C. Morrison
- The University of Kansas Cancer Center and the Departments of Pathology/Laboratory Medicine, Microbiology/Molecular Genetics/Immunology, and Anatomy/Cell Biology, University of Kansas Medical Center, Kansas City, KS, USA, Division of Cardiology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - J.S. Hunt
- The University of Kansas Cancer Center and the Departments of Pathology/Laboratory Medicine, Microbiology/Molecular Genetics/Immunology, and Anatomy/Cell Biology, University of Kansas Medical Center, Kansas City, KS, USA, Division of Cardiology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - S.W. Russell
- The University of Kansas Cancer Center and the Departments of Pathology/Laboratory Medicine, Microbiology/Molecular Genetics/Immunology, and Anatomy/Cell Biology, University of Kansas Medical Center, Kansas City, KS, USA, Division of Cardiology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
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Pradhan D, Krahling S, Williamson P, Schlegel RA. Multiple systems for recognition of apoptotic lymphocytes by macrophages. Mol Biol Cell 1997; 8:767-78. [PMID: 9168465 PMCID: PMC276128 DOI: 10.1091/mbc.8.5.767] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
In vivo, apoptotic lymphocytes are recognized and phagocytosed by macrophages well before the final stages of DNA degradation and cell lysis. The recognition process is apparently triggered by the exposure of phosphatidylserine (PS) on the cell surface, an event which precedes cell lysis by several hours. However, multiple receptors appear to respond to this event. We demonstrate here that both activated and unactivated macrophages recognize PS, but with different receptor systems. Phagocytosis of apoptotic lymphocytes by activated (but not by unactivated) macrophages is inhibited by pure PS vesicles as well as by N-acetylglucosamine, implicating involvement of a lectin-like receptor in this case. Conversely, uptake of apoptotic lymphocytes by unactivated (but not by activated) macrophages is inhibited by PS on the surface of erythrocytes as well as by the tetrapeptide RGDS and cationic amino acids and sugars, implicating involvement of the vitronectin receptor in this case. Recognition by both classes of macrophages is blocked by the monocyte-specific monoclonal antibody 61D3. The signal recognized by activated macrophages appears to develop on the lymphocyte prior to assembly of the signal recognized by unactivated macrophages. Collectively, these results suggest that PS exposure on the surface of apoptotic lymphocytes generates a complex and evolving signal recognized by different receptor complexes on activated and unactivated macrophages.
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Affiliation(s)
- D Pradhan
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park 16802, USA
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