title: Inflammatory responses involving tumor necrosis factor receptor-associated factor 6 contribute to in-stent lesion formation in a stent implantation model of rabbit carotid artery.
abstract: OBJECTIVE
  Inflammatory responses are considered to represent a unique property after stent implantation, and we previously demonstrated that inflammatory signaling involving tumor necrosis factor receptor-associated factor 6 (TRAF6) contributes to neointimal formation in a balloon injury model of rabbit carotid artery. The purpose of this study was to examine the role of TRAF6 in in-stent lesion formation after stent implantation in the rabbit carotid artery.
  
  
  METHODS
  Rabbit carotid arteries were injured with a 2F Fogarty catheter, and 28 days later, the same arteries were implanted with a 3-mm-diameter Palmaz-Schatz stent. A dominant negative (DN) form of TRAF6 (pME-FLAG-T6deltaRZ5) was then transferred using a plasmid-based electroporation method. Its effects were evaluated compared with the findings in arteries treated with control plasmid (pME-FLAG).
  
  
  RESULTS
  Immunostaining with anti-FLAG tag antibody showed that an expression plasmid vector containing the DN-TRAF6 sequence was successfully transferred to the arterial intima and media. Morphometric analyses revealed that the increase of intimal area in in-stent lesions was significantly inhibited by DN-TRAF6 14 days after stent implantation (DN-TRAF6 group, 3.01 +/- 0.25 x 10(5) microm2 vs control group, 4.25 +/- 0.23 x 10(5) microm2, P < .01), and the cell density was increased compared with that in the control group. In the DN-TRAF6 plasmid-treated vessels, cell replication was prevented in both the intima and media, and fewer leukocytes adhered to the luminal surface. Moreover, DN-TRAF6 suppressed macrophage infiltration, activation of proteases, and proteoglycan accumulation in the in-stent intima.
  
  
  CONCLUSIONS
  These findings suggest that TRAF6 plays an important role in cell replication, inflammatory cell infiltration, protease activity, and extracellular matrix accumulation that contributes to in-stent lesion development.
authors.affiliation: Department of Vascular Regeneration, Graduate School of Medicine, The University of Tokyo, Hongo, Tokyo, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Miyahara
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Koyama
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Miyata
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Shigematsu
authors.forename: Jun-Ichiro
authors.initials: J
authors.lastname: Inoue
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Takato
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Nagawa
mesh_terms: D000818:Animals; D002339:Carotid Arteries / Q000473:pathology*; D002452:Cell Count; D018274:Electroporation; D008297:Male; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D011817:Rabbits; D015607:Stents / Q000009:adverse effects*; D048029:TNF Receptor-Associated Factor 6 / Q000502:physiology*; D017539:Tunica Intima / Q000473:pathology; D017540:Tunica Media / Q000473:pathology
chemical_list: D048029:TNF Receptor-Associated Factor 6