title: Synergistic effect of pro-inflammatory TNFα and IL-17 in periostin mediated collagen deposition: potential role in liver fibrosis.
abstract: BACKGROUND
  The pro-inflammatory cytokines, tumor necrosis factor (TNF)-α, and interleukin (IL)-17, have been implicated in the pathogenesis of liver fibrosis. In this study, we investigated the role of TNFα and IL-17 toward induction of profibrotic factor, periostin.
  
  
  METHODS
  HepG2 cells were cultured and treated with inflammatory cytokines, TNFα and IL-17. Computational promoter sequence analysis of the periostin promoter was performed to define the putative binding sites for transcription factors. Transcription factors were analyzed by Western blot and Chromatin Immunoprecipitation. Periostin and transcription factor expression analysis was performed by RT-PCR, Western blot, and fluorescence microscopy. Type I collagen expression from fibroblast cultures was analyzed by Western blot and Sircol soluble collagen assay.
  
  
  RESULTS
  Activation of HepG2 Cells with TNFα and IL-17 enhanced the expression of periostin (3.5 and 4.4 fold, respectively p<0.05) compared to untreated cells. However, combined treatment with both TNFα and IL-17 at similar concentration demonstrated a 13.3 fold increase in periostin (p<0.01), thus suggesting a synergistic role of these cytokines. Periostin promoter analysis and specific siRNA knock-down revealed that TNFα induces periostin through cJun, while IL-17 induced periostin via STAT-3 signaling mechanisms. Treatment of the supernatant from the cytokine activated HepG2 cells on fibroblast cultures induced enhanced expression of type I collagen (>9.1 fold, p<0.01), indicative of a direct fibrogenic effect of TNFα and IL-17.
  
  
  CONCLUSIONS
  TNFα and IL-17 induced fibrogenesis through cJun and STAT-3 mediated expression of profibrotic biomarker, periostin. Therefore, periostin might serve as a novel biomarker in early diagnosis of liver fibrosis.
authors.affiliation: Department of Medicine, Mercy Hospital, St Louis, MO, USA.
authors.forename: Suneetha
authors.initials: S
authors.lastname: Amara
authors.affiliation: Department of Biological Sciences, Tennessee State University, Nashville, TN, USA.
authors.forename: Karina
authors.initials: K
authors.lastname: Lopez
authors.affiliation: Department of Surgery, Washington University School of Medicine, St Louis, MO, USA.
authors.forename: Babak
authors.initials: B
authors.lastname: Banan
authors.affiliation: Department of Biological Sciences, Tennessee State University, Nashville, TN, USA.
authors.forename: Sade-Kemi
authors.initials: SK
authors.lastname: Brown
authors.affiliation: Department of Chemistry, Tennessee State University, Nashville, TN, USA.
authors.forename: Margaret
authors.initials: M
authors.lastname: Whalen
authors.affiliation: Department of Biological Sciences, Tennessee State University, Nashville, TN, USA.
authors.forename: Elbert
authors.initials: E
authors.lastname: Myles
authors.affiliation: Department of Biological Sciences, Tennessee State University, Nashville, TN, USA.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Ivy
authors.affiliation: Department of Biological Sciences, Tennessee State University, Nashville, TN, USA.
authors.forename: Terrance
authors.initials: T
authors.lastname: Johnson
authors.affiliation: Department of Biochemistry, Mass Spectrometry and Proteomics Research Core, Vanderbilt University, Nashville, TN, USA.
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Schey
authors.affiliation: Department of Biological Sciences, Tennessee State University, Nashville, TN, USA. Electronic address: vtirivee@tnstate.edu.
authors.forename: Venkataswarup
authors.initials: V
authors.lastname: Tiriveedhi
mesh_terms: D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D024042:Collagen Type I / Q000235:genetics / Q000378:metabolism*; D004273:DNA, Neoplasm / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D056945:Hep G2 Cells; D006801:Humans; D018836:Inflammation Mediators / Q000494:pharmacology*; D020381:Interleukin-17 / Q000494:pharmacology*; D008103:Liver Cirrhosis / Q000378:metabolism* / Q000473:pathology*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000378:metabolism; D014158:Transcription, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D015815:Cell Adhesion Molecules; D024042:Collagen Type I; D004273:DNA, Neoplasm; D018836:Inflammation Mediators; D020381:Interleukin-17; C512835:POSTN protein, human; D016755:Proto-Oncogene Proteins c-jun; D050796:STAT3 Transcription Factor; D014409:Tumor Necrosis Factor-alpha
keywords: Fibrosis; Inflammation; Interleukin; Periostin; Transcription factors; Tumor necrosis factor