title: Role of endogenous IL-10 in LPS-induced STAT3 activation and IL-1 receptor antagonist gene expression.
abstract: The regulation of secretory interleukin (IL)-1 receptor antagonist (sIL-1Ra) in response to IL-10 is unique. In contrast to most cytokines, the lipopolysaccharide (LPS)-induced expression of the sIL-1Ra gene is enhanced by concomitant treatment with IL-10. Cotreatment of RAW 264.7 cells with IL-10 + LPS resulted in at least a twofold increase in sIL-1Ra promoter activity and mRNA expression compared with LPS alone; IL-10 alone had no effect on promoter activity or mRNA expression. Examination of sIL-1Ra mRNA expression in bone marrow-derived macrophages (BMDM) resulted in identical results. Transfection of RAW 264.7 cells with the sIL-1Ra/luc reporter and a dominant-negative signal transducer and activator of transcription (STAT)3 (Y705A) expression plasmid inhibited the enhanced response induced by exogenous IL-10 in the presence of LPS. The presence of a functional STAT3-binding site within the proximal sIL-1Ra promoter was demonstrated. As IL-10 is produced by LPS-stimulated macrophages, a role for endogenously produced IL-10 in the response of the sIL-1Ra gene to LPS was suggested. This was confirmed in IL-10-deficient BMDM, which when compared with normal BMDM, had significantly decreased LPS-induced sIL-1Ra mRNA levels that could be restored by exogenously provided IL-10, which induced a fivefold increase of LPS-induced IL-1Ra mRNA in cells from IL-10-/- BMDM. Western blot analysis of phosphorylated STAT3 from wild-type and IL-10-/- BMDM and IL-10 neutralization experiments demonstrated a role for endogenously produced IL-10 in the LPS-induced STAT3 activity. Together, these results demonstrate that endogenously produced IL-10 plays a significant role in LPS-induced sIL-1Ra gene expression via the activation of STAT3.
authors.affiliation: University of Virginia Health System, Department of Medicine, Digestive Health Center of Excellence and Microbiology, Charlottesville, VA 22908-0708, USA.
authors.forename: Virginia S
authors.initials: VS
authors.lastname: Carl
authors.forename: Jitendra K
authors.initials: JK
authors.lastname: Gautam
authors.forename: Laurey D
authors.initials: LD
authors.lastname: Comeau
authors.forename: Michael F
authors.initials: MF
authors.lastname: Smith
mesh_terms: D000818:Animals; D002460:Cell Line; D002634:Chemotaxis, Leukocyte / Q000187:drug effects / Q000235:genetics / Q000276:immunology*; D004268:DNA-Binding Proteins / Q000276:immunology / Q000378:metabolism*; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics / Q000276:immunology*; D053590:Interleukin 1 Receptor Antagonist Protein; D016753:Interleukin-10 / Q000276:immunology / Q000494:pharmacology / Q000502:physiology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects / Q000276:immunology*; D051379:Mice; D018345:Mice, Knockout; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000235:genetics; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D050796:STAT3 Transcription Factor; D012795:Sialoglycoproteins / Q000235:genetics*; D015534:Trans-Activators / Q000276:immunology / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics / Q000276:immunology
chemical_list: D004268:DNA-Binding Proteins; C507764:Il1rn protein, mouse; D053590:Interleukin 1 Receptor Antagonist Protein; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D050796:STAT3 Transcription Factor; D012795:Sialoglycoproteins; C494087:Stat3 protein, mouse; D015534:Trans-Activators; D016753:Interleukin-10