The Mitochondrial Network of Human Neutrophils: Role in Chemotaxis, Phagocytosis, Respiratory Burst Activation, and Commitment to Apoptosis

It is commonly assumed that human neutrophils possess few, if any, functional mitochondria and that they do not depend on these organelles for cell function. We have used the fluorescent mitochondrial indicators, JC-1, MitoTracker Red, and dihydrorhodamine 123 to show that live neutrophils possess a...

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Bibliographic Details
Published in:The Journal of immunology (1950) 2003-02, Vol.170 (4), p.1964-1972
Main Authors: Fossati, Gianluca, Moulding, Dale A, Spiller, David G, Moots, Robert J, White, Michael R. H, Edwards, Steven W
Format: Article
Language:English
Subjects:
Apoptosis - drug effects
Apoptosis - physiology
Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone - pharmacology
Cells, Cultured
Chemotaxis, Leukocyte - drug effects
Chemotaxis, Leukocyte - physiology
Fluorescent Dyes - analysis
Humans
Intracellular Membranes - drug effects
Intracellular Membranes - physiology
Male
Membrane Potentials - drug effects
Membrane Potentials - physiology
Microscopy, Confocal
Microscopy, Fluorescence
Mitochondria - chemistry
Mitochondria - drug effects
Mitochondria - metabolism
Mitochondria - physiology
Neutrophil Activation - physiology
Neutrophils - cytology
Neutrophils - drug effects
Neutrophils - metabolism
Neutrophils - physiology
Oligomycins - pharmacology
Phagocytosis - physiology
Respiratory Burst - drug effects
Respiratory Burst - physiology
Rhodamines - antagonists & inhibitors
Uncoupling Agents - pharmacology
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Summary:It is commonly assumed that human neutrophils possess few, if any, functional mitochondria and that they do not depend on these organelles for cell function. We have used the fluorescent mitochondrial indicators, JC-1, MitoTracker Red, and dihydrorhodamine 123 to show that live neutrophils possess a complex mitochondrial network that extends through the cytoplasm. The membrane potential of these mitochondria was rapidly (within 2 min) disrupted by the addition of FCCP (IC(50) = 20 nM), but not by the Fo-ATPase inhibitor, oligomycin (at up to 7 microg/ml). However, inhibition of mitochondrial function with both agents resulted in cell shape changes. Neither activation of the respiratory burst nor phagocytosis of either latex particles or serum-opsonized Staphylococcus aureus was affected by the addition of FCCP or oligomycin. However, FCCP inhibited chemotaxis at concentrations that paralleled disruption of mitochondrial membrane potential. Furthermore, prolonged (2-h) incubation with oligomycin resulted in an impaired ability to activate a respiratory burst and also inhibited chemotaxis. These observations indicate that intact mitochondrial function is required to sustain some neutrophil functions, but not for the rapid initiation of the respiratory burst or phagocytosis. Loss of mitochondrial membrane potential was a very early marker for commitment of neutrophils into apoptosis and preceded the appearance of phosphatidylserine on the cell surface. However, inhibition of mitochondrial function did not accelerate the rate of neutrophil apoptosis. These data shed important insights into the hitherto unrecognized importance of mitochondria in the function of neutrophils during infection and inflammation.
ISSN:0022-1767
1550-6606
DOI:10.4049/jimmunol.170.4.1964