title: Crucial Role of the Aryl Hydrocarbon Receptor (AhR) in Indoxyl Sulfate-Induced Vascular Inflammation.
abstract: OBJECTIVE
  The aryl hydrocarbon receptor (AhR), a ligand-inducible transcription factor mediating toxic effects of dioxins and uremic toxins, has recently emerged as a pathophysiological regulator of immune-inflammatory conditions. Indoxyl sulfate, a uremic toxin, is associated with cardiovascular disease in patients with chronic kidney disease and has been shown to be a ligand for AhR. The aim of this study was to investigate the potential role of AhR in indoxyl sulfate-induced leukocyte-endothelial interactions.
  
  
  METHODS
  Endothelial cell-specific AhR knockout (eAhR KO) mice were produced by crossing AhR floxed mice with Tie2 Cre mice. Indoxyl sulfate was administered for 2 weeks, followed by injection of TNF-α. Leukocyte recruitment to the femoral artery was assessed by intravital microscopy. Vascular endothelial cells were transfected with siRNA specific to AhR (siAhR) and treated with indoxyl sulfate, followed by stimulation with TNF-α.
  
  
  RESULTS
  Indoxyl sulfate dramatically enhanced TNF-α-induced leukocyte recruitment to the vascular wall in control animals but not in eAhR KO mice. In endothelial cells, siAhR significantly reduced indoxyl sulfate-enhanced leukocyte adhesion as well as E-selectin expression, whereas the activation of JNK and nuclear factor-κB was not affected. A luciferase assay revealed that the region between －153 and －146 bps in the E-selectin promoter was responsible for indoxyl sulfate activity via AhR. Mutational analysis of this region revealed that activator protein-1 (AP-1) is responsible for indoxyl sulfate-triggered E-selectin expression via AhR.
  
  
  CONCLUSIONS
  AhR mediates indoxyl sulfate-enhanced leukocyte-endothelial interactions through AP-1 transcriptional activity, which may constitute a new mechanism of vascular inflammation in patients with renal disease.
authors: Life Science and Bioethics, Department of International Health Development, Tokyo Medical and Dental University.
authors: Shunsuke
authors: S
authors: Ito
authors: Mizuko
authors: M
authors: Osaka
authors: Takeo
authors: T
authors: Edamatsu
authors: Yoshiharu
authors: Y
authors: Itoh
authors: Masayuki
authors: M
authors: Yoshida
mesh_terms: D000818:Animals; D001167:Arteritis / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology*; D051792:Basic Helix-Loop-Helix Proteins / Q000502:physiology*; D015153:Blotting, Western; D002448:Cell Adhesion; D002478:Cells, Cultured; D047369:Chromatin Immunoprecipitation; D019040:E-Selectin / Q000235:genetics / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D005260:Female; D006801:Humans; D007200:Indican / Q000633:toxicity*; D007962:Leukocytes / Q000378:metabolism; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D018336:Receptors, Aryl Hydrocarbon / Q000502:physiology*; D014162:Transfection
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D019040:E-Selectin; D007200:Indican; D016328:NF-kappa B; D017382:Reactive Oxygen Species; D018336:Receptors, Aryl Hydrocarbon; C484722:Ahr protein, mouse