Ward M R, Sasahara T, Agrotis A, Dilley R J, Jennings G L, Bobik A
Cell Biology Laboratory, Baker Medical Research Institute, Prahran, VIC, Australia.
Atherosclerosis. 1998 Apr;137(2):267-75. doi: 10.1016/s0021-9150(97)00275-x.
Tranilast (N(3,4-dimethoxycinnamoyl)anthranilic acid), an agent which in cell culture inhibits transforming growth factor-beta (TGF-beta) secretion and antagonises the effects of TGF-beta and platelet-derived growth factor (PDGF) on cell migration and proliferation, has been reported to reduce the incidence of restenosis after angioplasty in angiographically validated human clinical trials. We investigated in a rat model of balloon angioplasty whether tranilast's effects in vivo could be attributed to inhibition of expression of TGF-beta and/or its receptor types. Using a standardised reverse transcriptase-polymerase chain reaction (RT-PCR) assay, we examined the effects of three doses of tranilast (25, 50 and 100 mg/kg) on the expression of two TGF-beta isoforms, the types I and II TGF-beta receptors and two putative TGF-beta responses, induction of integrins alpha(v) and beta3 mRNA, 2 h after oral administration and 26 h after vessel injury. Tranilast attenuated in a dose-dependent and reversible manner the injury-induced increases in mRNA levels encoding TGF-beta1, TGF-beta3, two type I TGF-beta receptors ALK-5 and ALK-2, and the type II receptor TbetaRII. At the highest dose mRNA levels encoding TGF-beta1 and TbetaRII were attenuated to levels approaching or below those observed in uninjured vessels. Messenger RNAs encoding TGF-beta3, ALK-5 and ALK-2 were all attenuated by between 70 and 74% (all P < 0.05). Tranilast also attenuated in a reversible manner the elevations in mRNA levels for integrins alpha(v) and beta3 observed after vessel injury, by 90 and 72%, respectively. We also investigated, in cultured smooth muscle cells derived from injured carotid arteries, the extent to which tranilast (300 mg/l) attenuated any increases in expression of type I and type II receptors stimulated by PDGF-BB and TGF-beta1, growth factors implicated in smooth muscle cell migration and proliferation in injured vessels. Increases in mRNA levels of the type I receptors ALK-5 and ALK-2 induced by PDGF-BB and TGF-beta1 were almost completely prevented by tranilast. Tranilast also prevented the PDGF-BB induced increases in TbetaRII but only partially inhibited the TGF-beta1 induced upregulation of TbetaRII. We conclude that tranilast can inhibit transcriptional mechanisms associated with the upregulation of TGF-beta and its receptor types in balloon catheter injured vessels. It is possible that these mechanisms contribute to its ability to reduce the frequency of restenosis after angioplasty.
曲尼司特（N-(3,4-二甲氧基肉桂酰)邻氨基苯甲酸），一种在细胞培养中可抑制转化生长因子-β（TGF-β）分泌，并拮抗TGF-β和血小板衍生生长因子（PDGF）对细胞迁移和增殖作用的药物，在经血管造影验证的人体临床试验中已被报道可降低血管成形术后再狭窄的发生率。我们在大鼠球囊血管成形术模型中研究了曲尼司特在体内的作用是否可归因于对TGF-β及其受体类型表达的抑制。使用标准化的逆转录聚合酶链反应（RT-PCR）测定法，我们检测了三种剂量的曲尼司特（25、50和100mg/kg）在口服给药后2小时和血管损伤后26小时对两种TGF-β同工型、I型和II型TGF-β受体以及两种假定的TGF-β反应（整合素α(v)和β3 mRNA的诱导）表达的影响。曲尼司特以剂量依赖性和可逆的方式减弱了损伤诱导的编码TGF-β1、TGF-β3、两种I型TGF-β受体ALK-5和ALK-2以及II型受体TβRII的mRNA水平的增加。在最高剂量下，编码TGF-β1和TβRII的mRNA水平减弱至接近或低于未损伤血管中观察到的水平。编码TGF-β3、ALK-5和ALK-2的信使RNA均减弱了70%至74%（所有P<0.05）。曲尼司特还以可逆的方式分别将血管损伤后观察到的整合素α(v)和β3的mRNA水平升高减弱了90%和72%。我们还在源自损伤颈动脉的培养平滑肌细胞中研究了曲尼司特（300mg/l）减弱PDGF-BB和TGF-β1刺激的I型和II型受体表达增加的程度，PDGF-BB和TGF-β1是与损伤血管中平滑肌细胞迁移和增殖相关的生长因子。曲尼司特几乎完全阻止了PDGF-BB和TGF-β1诱导的I型受体ALK-5和ALK-2的mRNA水平增加。曲尼司特还阻止了PDGF-BB诱导的TβRII增加，但仅部分抑制了TGF-β1诱导的TβRII上调。我们得出结论，曲尼司特可抑制与球囊导管损伤血管中TGF-β及其受体类型上调相关的转录机制。这些机制可能有助于其降低血管成形术后再狭窄频率的能力。
