title: Regulation of monocyte IL-10 synthesis by endogenous IL-1 and TNF-alpha: role of the p38 and p42/44 mitogen-activated protein kinases.
abstract: IL-10 is an anti-inflammatory cytokine with potent immunomodulatory effects, including inhibition of cytokine production. However, regulation of monocyte IL-10 production is poorly understood. In this report we have investigated the mechanisms of LPS-induced IL-10 production by human peripheral blood monocytes and demonstrate that IL-10 synthesis is uniquely dependent on the endogenous proinflammatory cytokines IL-1 and/or TNF-alpha. LPS signal transduction in monocytes has been shown to involve activation of the p38 and p42 mitogen-activated protein kinase (MAPK) cascades. The results in this paper indicate that inhibition of p38 MAPK potently inhibited the production of IL-10, IL-1beta, and TNF-alpha, whereas blockade of the p42/44 MAPK pathway, while partially inhibiting TNF-alpha and IL-1beta production, had no effect on monocyte secretion of IL-10. Furthermore, neither the inhibition of monocyte TNF-alpha induced by IL-10 nor the stimulation of soluble TNF receptor production was affected by inhibition of the p42/44 MAPK pathway, suggesting that this signaling event is not involved in either monocyte production of or anti-inflammatory responses to IL-10. These data raise the interesting possibility that proinflammatory TNF-alpha-mediated effects may be selectively blocked without modulating the induction or the response to IL-10, whereas the signaling events associated with the anti-inflammatory events induced by IL-10 remain to be elucidated.
authors.affiliation: Kennedy Institute of Rheumatology, Hammersmith, London, United Kingdom.
authors.forename: A D
authors.initials: AD
authors.lastname: Foey
authors.forename: S L
authors.initials: SL
authors.lastname: Parry
authors.forename: L M
authors.initials: LM
authors.lastname: Williams
authors.forename: M
authors.initials: M
authors.lastname: Feldmann
authors.forename: B M
authors.initials: BM
authors.lastname: Foxwell
authors.forename: F M
authors.initials: FM
authors.lastname: Brennan
mesh_terms: D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000502:physiology*; D006801:Humans; D007375:Interleukin-1 / Q000096:biosynthesis / Q000502:physiology*; D016753:Interleukin-10 / Q000096:biosynthesis*; D047908:Intracellular Signaling Peptides and Proteins; D008070:Lipopolysaccharides / Q000494:pharmacology; D008262:Macrophage Activation / Q000187:drug effects; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000502:physiology*; D020928:Mitogen-Activated Protein Kinases; D009000:Monocytes / Q000201:enzymology* / Q000276:immunology / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D013379:Substrate Specificity / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000502:physiology*; D048051:p38 Mitogen-Activated Protein Kinases; D000099190:MAP-Kinase-Activated Kinase 2
chemical_list: D017871:Calcium-Calmodulin-Dependent Protein Kinases; D007375:Interleukin-1; D016753:Interleukin-10; D047908:Intracellular Signaling Peptides and Proteins; D008070:Lipopolysaccharides; D019950:Mitogen-Activated Protein Kinase 1; D020928:Mitogen-Activated Protein Kinases; D017346:Protein Serine-Threonine Kinases; D014409:Tumor Necrosis Factor-alpha; D048051:p38 Mitogen-Activated Protein Kinases; D000099190:MAP-Kinase-Activated Kinase 2