title: Granulocyte-macrophage colony-stimulating factor regulates cytokine production in cultured macrophages through CD14-dependent and -independent mechanisms.
abstract: Granulocyte-macrophage colony-stimulating factor (GM-CSF) has multiple effects on the antigen phenotype and function of macrophages. In this study we investigated the effect of GM-CSF on cytokine production by macrophages. We found that GM-CSF may modify the tumour necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) response to lipopolysaccharide (LPS) through two different mechanisms. Relatively early in culture, GM-CSF increases the amount of cytokines synthesized by responding cells; this effect appears to be unrelated to modulation of CD14 expression and LPS-binding capacity. After prolonged incubation, GM-CSF up-regulates both CD14 expression and LPS-binding capacity, and the frequency of cytokine-producing cells. Release of CD14 in the culture supernatant was decreased in the presence of GM-CSF, suggesting that a reduced shedding was responsible for the effect of GM-CSF on CD14 expression. Enhancement of cytokine production was also observed in GM-CSF-treated macrophages after stimulation by phorbol 12-myristate 13-acetate (PMA), thus indicating that GM-CSF affects both CD14-dependent and -independent cytokine production. Finally, GM-CSF did not modulate the LPS- and PMA-induced production of IL-10 and IL-12. We conclude that GM-CSF may play a role in manipulating the activation-induced expression of pro-inflammatory cytokines by macrophages. Enhanced production of these cytokines could play an important role in the pathogenesis of Gram-negative septic shock syndrome and in defence against infectious agents.
authors.affiliation: Department of Public Health and Cellular Biology, Chair of Infectious Diseases, University of Rome 'Tor Vergata', Rome, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Bergamini
authors.forename: F
authors.initials: F
authors.lastname: Bolacchi
authors.forename: B
authors.initials: B
authors.lastname: Bongiovanni
authors.forename: M
authors.initials: M
authors.lastname: Cepparulo
authors.forename: L
authors.initials: L
authors.lastname: Ventura
authors.forename: M
authors.initials: M
authors.lastname: Capozzi
authors.forename: C
authors.initials: C
authors.lastname: Sarrecchia
authors.forename: G
authors.initials: G
authors.lastname: Rocchi
mesh_terms: D018929:Cell Culture Techniques; D002470:Cell Survival / Q000276:immunology; D016207:Cytokines / Q000096:biosynthesis*; D005434:Flow Cytometry; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000276:immunology*; D006801:Humans; D015850:Interleukin-6 / Q000096:biosynthesis; D018950:Lipopolysaccharide Receptors / Q000276:immunology*; D008070:Lipopolysaccharides / Q000378:metabolism; D008262:Macrophage Activation / Q000276:immunology; D016173:Macrophage Colony-Stimulating Factor / Q000276:immunology; D008264:Macrophages / Q000276:immunology* / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
chemical_list: D016207:Cytokines; D015850:Interleukin-6; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D016173:Macrophage Colony-Stimulating Factor; D016178:Granulocyte-Macrophage Colony-Stimulating Factor