title: IL-10 disrupts the Brd4-docking sites to inhibit LPS-induced CXCL8 and TNF-α expression in monocytes: Implications for chronic obstructive pulmonary disease.
abstract: BACKGROUND
  IL-10 is well known for its ability to block the expression and production of numerous proinflammatory cytokines, in this manner preventing the development of excessive or chronic immune activation. IL-10-induced transcriptional repression of CXCL8 and TNFA genes consists of 2 distinct phases: an early phase, occurring rapidly and in a protein synthesis-independent manner, followed by a second phase that is more delayed and dependent on protein synthesis.
  
  
  OBJECTIVE
  We sought to identify the mechanisms through which IL-10 rapidly and directly suppresses LPS-induced CXCL8 and TNF-α transcription, which might be defective under pathologic conditions.
  
  
  METHODS
  The molecular events triggered by IL-10 in LPS-activated monocytes at the CXCL8 and TNFA loci were investigated by using the chromatin immunoprecipitation assay.
  
  
  RESULTS
  Inhibition of LPS-induced CXCL8 and TNF-α expression by IL-10 proceeds through a common mechanism targeting LPS-induced phosphorylation of the nuclear factor κB p65 serine 276 residue (pS276p65). As a result, all the pS276p65-dependent events occurring at the CXCL8 and TNFA loci are consistently reduced, ultimately leading to a reduction in transcript elongation. Additionally, IL-10 selectively controls CXCL8 transcript elongation through histone deacetylase (HDAC) 2-dependent covalent chromatin modifications, disrupting the assembly of the transcriptional machinery. Remarkably, PBMCs from patients with acute-phase chronic obstructive pulmonary disease, which express negligible HDAC2 levels, are scarcely affected by IL-10 in terms of inhibition of CXCL8 expression.
  
  
  CONCLUSIONS
  This study provides mechanistic evidence that IL-10 creates a chromatin environment that decreases the transcriptional rate of CXCL8 and TNF-α to Toll-like receptor 4-activating signals. Data identify novel molecular targets for therapeutic strategies aimed at dampening inflammation in pathologies such as chronic obstructive pulmonary disease, in which reduced intracellular HDAC2 levels have been described.
authors.affiliation: Department of Pathology and Diagnostics, Division of General Pathology, University of Verona, Verona, Italy.
authors.forename: Monica
authors.initials: M
authors.lastname: Castellucci
authors.affiliation: Department of Pathology and Diagnostics, Division of General Pathology, University of Verona, Verona, Italy.
authors.forename: Marzia
authors.initials: M
authors.lastname: Rossato
authors.affiliation: Department of Pathology and Diagnostics, Division of General Pathology, University of Verona, Verona, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Calzetti
authors.affiliation: Department of Pathology and Diagnostics, Division of General Pathology, University of Verona, Verona, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Tamassia
authors.affiliation: Ospedale San Pellegrino, Castiglione delle Stiviere, Mantova, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Zeminian
authors.affiliation: Department of Pathology and Diagnostics, Division of General Pathology, University of Verona, Verona, Italy.
authors.forename: Marco A
authors.initials: MA
authors.lastname: Cassatella
authors.affiliation: Department of Pathology and Diagnostics, Division of General Pathology, University of Verona, Verona, Italy. Electronic address: flavia.bazzoni@univr.it.
authors.forename: Flavia
authors.initials: F
authors.lastname: Bazzoni
mesh_terms: D000328:Adult; D000368:Aged; D001665:Binding Sites; D016022:Case-Control Studies; D018797:Cell Cycle Proteins; D005260:Female; D005786:Gene Expression Regulation; D056464:Histone Deacetylase 2 / Q000235:genetics / Q000276:immunology; D006801:Humans; D016753:Interleukin-10 / Q000276:immunology* / Q000378:metabolism / Q000494:pharmacology; D016209:Interleukin-8 / Q000235:genetics / Q000276:immunology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D009000:Monocytes / Q000187:drug effects / Q000276:immunology* / Q000473:pathology; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D061251:Primary Cell Culture; D011485:Protein Binding; D029424:Pulmonary Disease, Chronic Obstructive / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D015398:Signal Transduction; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000276:immunology; D051996:Transcription Factor RelA / Q000235:genetics / Q000276:immunology; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D014158:Transcription, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000276:immunology*; D000092468:Bromodomain Containing Proteins
chemical_list: D018797:Cell Cycle Proteins; D056464:Histone Deacetylase 2; D016753:Interleukin-10; D016209:Interleukin-8; D008070:Lipopolysaccharides; D009687:Nuclear Proteins; D051197:Toll-Like Receptor 4; D051996:Transcription Factor RelA; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; C441289:BRD4 protein, human; D000092468:Bromodomain Containing Proteins; C508606:CXCL8 protein, human; C508609:IL10 protein, human; C495345:TLR4 protein, human; C533423:HDAC2 protein, human
keywords: Brd4-docking site; CXCL8; IL-10; TNF-α; chronic obstructive pulmonary disease; histone deacetylase 2; nuclear factor κB; transcriptional inhibition