Impairment of growth of Listeria monocytogenes in THP-1 macrophages by granulocyte macrophage colony-stimulating factor: release of tumor necrosis factor-alpha and nitric oxide.
BACKGROUND
Listeria monocytogenes tends to survive in phagocytes. Granulocyte macrophage colony-stimulating factor (GM-CSF) protects mice against L. monocytogenes infection, and mice knocked out for the GM-CSF gene are more susceptible to these infections.


METHODS
THP-1 cells were used to characterize the GM-CSF receptor (binding isotherms; STAT5 phosphorylation), measure the intracellular growth of L. monocytogenes (5 h after phagocytosis), examine the influence of a 24-h incubation with GM-CSF before infection, measure the production of tumor necrosis factor (TNF)-alpha and the expression of nitric oxide synthase (iNOS), and evaluate the influence of anti-GM-CSF receptor (GM-CSFR alpha ) and anti-TNF-alpha antibodies and the addition of N(omega)-nitro-L-arginine methyl ester (L-NAME) and catalase.


RESULTS
THP-1 cells display functional GM-CSFR alpha. GM-CSF impairs the intracellular growth of L. monocytogenes to approximately 65% of its value in unstimulated cells. This effect is abolished by anti-GM-CSFR alpha, anti-TNF-alpha antibodies, and catalase (and, to a lesser extent, by L-NAME). GM-CSF stimulates the release of TNF-alpha and the expression of iNOS. TNF-alpha added to unstimulated cells (even in large amounts) does not fully reproduce the impairment in the growth of L. monocytogenes caused by GM-CSF.


CONCLUSIONS
GM-CSF impairs the intracellular growth of L. monocytogenes by a synergistic action of the GM-CSF-triggered release of autocrine TNF-alpha and hydrogen peroxide and the production of NO (associated with the stimulation of the expression of iNOS).
Carryn
Stéphane
S
Unité de Pharmacologie Cellulaire et Moléculaire, Université Catholique de Louvain, Brussels, Belgium.
Van de Velde
Sébastien
S
Van Bambeke
Françoise
F
Mingeot-Leclercq
Marie-Paule
MP
Tulkens
Paul M
PM
D015153:Blotting, Western; D002374:Catalase / Q000494:pharmacology; D015169:Colony Count, Microbial; D004797:Enzyme-Linked Immunosorbent Assay; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000276:immunology / Q000494:pharmacology*; D006801:Humans; D008089:Listeria monocytogenes / Q000201:enzymology / Q000254:growth & development*; D008088:Listeriosis / Q000276:immunology* / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism / Q000382:microbiology*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000096:biosynthesis / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor; D014409:Tumor Necrosis Factor-alpha; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D002374:Catalase; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D019331:NG-Nitroarginine Methyl Ester