Granulocyte-macrophage colony-stimulating factor modulates lipopolysaccharide (LPS)-binding and LPS-response of human macrophages: inverse regulation of tumour necrosis factor-alpha and interleukin-10.
Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a well-known stimulus for the activation, differentiation and survival of monocytes (MO). Up to now most investigations focused on the short-term effects of GM-CSF. In this study we investigated the effects of GM-CSF on the long-term differentiation of human MO in the presence of serum. We found that MO-derived macrophages (Mphi) cultured with serum plus GM-CSF (GM-Mphi) were different from control Mphi (SER-Mphi) in terms of lipopolysaccharide (LPS)-stimulated cytokine release: GM-Mphi showed an increased tumour necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) production, especially at lower LPS concentrations, but the secretion of IL-10 was diminished. In addition, GM-Mphi secreted TNF-alpha but not IL-6 and IL-10, spontaneously. The spontaneous TNF-alpha production was not due to LPS contamination as it could not be blocked by anti-CD14 antibody. Flow cytometry revealed, however, that the receptor for LPS, CD14, was up-regulated on GM-Mphi and those Mphi released twice as much soluble CD14 into the supernatant as compared with SER-Mphi. The higher CD14 expression also resulted in an enhanced LPS-binding capacity of GM-Mphi. Furthermore, the LPS-response of GM-Mphi could only be blocked by about fourfold higher concentration of anti-CD14 antibody compared with SER-Mphi. In summary, GM-CSF promotes the generation of a pro-inflammatory type of Mphi in two different ways: first, the down-regulation of autocrine IL-10 production increases the release of cytokines such as IL-6 and TNF-alpha and second, the up-regulation of membrane and soluble CD14 expression leads to a higher sensitivity towards LPS-stimulation.
Kreutz
M
M
University of Regensburg, Department of Haematology, Borstel, Germany.
Hennemann
B
B
Ackermann
U
U
Grage-Griebenow
E
E
Krause
S W
SW
Andreesen
R
R
D000911:Antibodies, Monoclonal / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D005434:Flow Cytometry; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D006801:Humans; D016753:Interleukin-10 / Q000378:metabolism*; D015850:Interleukin-6 / Q000378:metabolism; D018950:Lipopolysaccharide Receptors / Q000276:immunology; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects / Q000276:immunology*; D011485:Protein Binding; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D015850:Interleukin-6; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; D016178:Granulocyte-Macrophage Colony-Stimulating Factor