Abstract
As the first immune cells to infiltrate the nervous system after traumatic PNS and CNS injury, neutrophils (polymorphonuclear leukocytes, PMNs) may promote injury by releasing toxic soluble factors that may affect neuronal survival. Direct neurotoxicity of matrix metalloproteinases (MMPs), reactive oxygen species (ROS), and cytokines released by PMNs was investigated by culturing dorsal root ganglion (DRG) cells with PMN-conditioned media containing MMP inhibitor (GM6001), ROS scavengers, or tumor necrosis factor alphaR (TNF-alphaR) neutralizing antibody. Although DRGs exposed to PMN-conditioned media had 53% fewer surviving neurons than controls, neuronal cell loss was prevented by GM6001 (20 micromol/L), catalase (1000 U/mL), or TNF-alphaR neutralizing antibody (1.5 microg/mL), elevating survival to 77%, 94%, and 95%, respectively. In accordance with protection by GM6001, conditioned media collected from MMP-9 null PMNs was less neurotoxic than that collected from wild-type PMNs. Additionally, MMP inhibition reduced PMN-derived ROS; removal of ROS reduced PMN-derived MMP-9 activity; and TNF-alpha inhibition reduced both PMN-derived MMP-9 activity and ROS in PMN cultures. Our data provide the first direct evidence that PMN-driven neurotoxicity is dependent on MMPs, ROS, and TNF-alpha, and that these factors may regulate PMN release of these soluble factors or interact with one another to mediate PMN-driven neurotoxicity.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Antibodies / pharmacology
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Brain Injuries / immunology
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Brain Injuries / metabolism
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Brain Injuries / physiopathology
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Cell Survival / drug effects
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Cell Survival / physiology
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Cells, Cultured
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Chemotaxis, Leukocyte / immunology
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Culture Media, Conditioned / pharmacology
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Encephalitis / immunology
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Encephalitis / metabolism*
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Encephalitis / physiopathology
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Enzyme Inhibitors / pharmacology
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Female
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Ganglia, Spinal / cytology
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Ganglia, Spinal / immunology
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Ganglia, Spinal / metabolism
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Matrix Metalloproteinase 9 / genetics
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Matrix Metalloproteinase 9 / metabolism*
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Matrix Metalloproteinase Inhibitors
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Matrix Metalloproteinases / metabolism*
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Mice
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Mice, Inbred C57BL
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Mice, Knockout
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Nerve Degeneration / immunology
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Nerve Degeneration / metabolism*
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Nerve Degeneration / physiopathology
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Neurons, Afferent / drug effects
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Neurons, Afferent / immunology
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Neurons, Afferent / metabolism
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Neurotoxins / immunology
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Neurotoxins / metabolism
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Neutrophils / immunology
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Neutrophils / metabolism*
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Oxidative Stress / physiology
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Reactive Oxygen Species / metabolism*
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Tumor Necrosis Factor-alpha / antagonists & inhibitors
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Tumor Necrosis Factor-alpha / metabolism*
Substances
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Antibodies
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Culture Media, Conditioned
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Enzyme Inhibitors
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Matrix Metalloproteinase Inhibitors
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Neurotoxins
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Reactive Oxygen Species
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Tumor Necrosis Factor-alpha
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Matrix Metalloproteinases
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Matrix Metalloproteinase 9