title: Roles of chymase in stenosis occurring after polytetrafluoroethylene graft implantations.
abstract: Chymase is an important enzyme for the generation of angiotensin (Ang) II and in the activation of transforming growth factor (TGF)-beta1. Therefore, chymase may be involved in the hemodialysis access dysfunction, which is caused by intimal hyperplasia that occurs after polytetrafluoroethylene (PTFE) graft implantations. Bilateral U-shaped PTFE grafts were placed between the femoral vein and artery in dogs. Chymase inhibitor (NK3201, 1 mg/kg per day, p.o.) treatments were initiated 3 days before the operation. After the implantation, the stenosis by neointima proliferation was most frequently observed in the venous side of the PTFE grafts. In the hyperplastic neointima, myofibroblasts were the main cellular components. On the other hand, fibroblasts only occupied cellular components in a much smaller proportion in the neointima. However, these cells seem to be rich in the properties of proliferation and migration. After PTFE graft implantations, extensive accumulations of chymase-positive mast cells were found mainly in the tissue surrounding the grafts. The Ang II- and TGF-beta-positive cells were found in an adjacent section that was in close proximity to the chymase-positive cells. In contrast, the AT(1) receptors, as well as TGF-beta type II receptors, were expressed either in the neointima or in the outside adventitia of the PTFE grafts. Chymase inhibitor treatment resulted in a reduction of chymase, Ang II and TGF-beta1 expression, leading to a significant inhibition of neointimal formation. These findings indicating that an increase of chymase via promoting Ang II and TGF-beta1 generation plays a pivotal role in the neointimal formation after the implantation of PTFE grafts and also suggesting that chymase inhibition may be a new strategy that can be used to prevent PTFE graft dysfunctions in clinical settings.
authors.affiliation: Department of Pharmacology, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki City, Osaka 569-8686, Japan. pha012@art.osaka-med.ac.jp
authors.forename: Denan
authors.initials: D
authors.lastname: Jin
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Ueda
authors.forename: Shinji
authors.initials: S
authors.lastname: Takai
authors.forename: Michiko
authors.initials: M
authors.lastname: Muramatsu
authors.forename: Keiichi
authors.initials: K
authors.lastname: Furubayashi
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Ibaraki
authors.forename: Kanta
authors.initials: K
authors.lastname: Kishi
authors.forename: Yoji
authors.initials: Y
authors.lastname: Katsuoka
authors.forename: Mizuo
authors.initials: M
authors.lastname: Miyazaki
mesh_terms: D000081:Acetamides / Q000494:pharmacology; D000818:Animals; D001166:Arteriovenous Shunt, Surgical / Q000009:adverse effects*; D049109:Cell Proliferation / Q000187:drug effects; D053818:Chymases / Q000037:antagonists & inhibitors / Q000502:physiology*; D003251:Constriction, Pathologic / Q000201:enzymology / Q000209:etiology / Q000473:pathology; D004285:Dogs; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005263:Femoral Artery / Q000201:enzymology / Q000473:pathology / Q000601:surgery; D005268:Femoral Vein / Q000201:enzymology / Q000473:pathology / Q000601:surgery; D008297:Male; D011138:Polytetrafluoroethylene; D011743:Pyrimidines / Q000494:pharmacology; D017539:Tunica Intima / Q000201:enzymology / Q000473:pathology
chemical_list: D000081:Acetamides; D004791:Enzyme Inhibitors; C437945:NK3201; D011743:Pyrimidines; D011138:Polytetrafluoroethylene; D053818:Chymases