Nakamura Yasuhiro, Suzuki Takashi, Sasano Hironobu
Department of Pathology, Tohoku University School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan.
J Steroid Biochem Mol Biol. 2005 Feb;93(2-5):263-8. doi: 10.1016/j.jsbmb.2004.12.024. Epub 2005 Jan 28.
Various epidemiological studies have demonstrated a relatively low incidence of cardiovascular events in premenopausal women and its marked increment after menopause. In addition, estrogens have been postulated to exert direct anti-atherogenic effects via binding to estrogen receptors (ERs) in vascular smooth muscle cells (VSMCs). However, not all postmenopausal women develop atherosclerosis despite decreased levels of serum estrogen. Therefore, it is considered important to examine the status of estrogen metabolism in situ and of ER expression in the human cardiovascular system. Estrone sulfate (E1S) is a major circulating plasma estrogen that is converted into the biologically active estrogen, estrone (E1) by steroid sulfatase (STS). E1 is also sulfated and reverted into E1S by estrogen sulfotransferase (EST). These two enzymes have recently been shown to play important roles in the in situ estrogen actions of estrogen-dependent human tissues. STS and EST, however, have not been studied in detail in the human vascular system associated with atherosclerotic changes. Therefore, the relative abundance of STS- and EST-immunoreactive protein and mRNA expression in human aorta were evaluated using immunohistochemistry and reverse transcription followed by quantitative polymerase chain reaction in addition to enzyme activity. Furthermore, we evaluated the relative abundance of messenger RNA (mRNA) of both ER subtypes (ERalpha and ERbeta) in the human aorta using reverse transcription followed by quantitative polymerase chain reaction (RT-qPCR), as well as the immunoreactivity of both ERs in VSMCs of human atherosclerotic lesions. STS expression levels were found to be significantly higher in the VSMCs obtained from female aortas with mild atherosclerotic changes than in those with severe atherosclerotic changes and in male aortas regardless of atherosclerotic changes. EST expression levels in the VSMCs of these aortas, however, were significantly higher in female aortas with severe atherosclerotic changes and in male aortas than in female aortas with mild atherosclerotic changes. In addition, the number of ERalpha and/or ERbeta double positive cells in the neointima was higher in female aortas with a mild degree of atherosclerosis than in female aortas with severe atherosclerosis. They indicate that both abundance of these estrogen-metabolizing enzymes in female aorta and relative levels of ER in VSMCs of female neointima may be associated with the status of atherosclerotic changes.
多项流行病学研究表明，绝经前女性心血管事件的发生率相对较低，而绝经后则显著增加。此外，有人提出雌激素通过与血管平滑肌细胞（VSMC）中的雌激素受体（ER）结合发挥直接的抗动脉粥样硬化作用。然而，尽管血清雌激素水平下降，但并非所有绝经后女性都会发生动脉粥样硬化。因此，研究人体心血管系统中雌激素代谢的原位状态和ER表达情况被认为很重要。硫酸雌酮（E1S）是一种主要的循环血浆雌激素，可通过类固醇硫酸酯酶（STS）转化为具有生物活性的雌激素雌酮（E1）。E1也会被硫酸化，并通过雌激素硫酸转移酶（EST）转化回E1S。最近发现这两种酶在雌激素依赖性人体组织的原位雌激素作用中发挥重要作用。然而，在与动脉粥样硬化变化相关的人体血管系统中，尚未对STS和EST进行详细研究。因此，除了酶活性外，还使用免疫组织化学和逆转录后定量聚合酶链反应来评估人主动脉中STS和EST免疫反应性蛋白的相对丰度以及mRNA表达。此外，我们使用逆转录后定量聚合酶链反应（RT-qPCR）评估了人主动脉中两种ER亚型（ERα和ERβ）的信使RNA（mRNA）的相对丰度，以及人动脉粥样硬化病变VSMC中两种ER的免疫反应性。结果发现，与严重动脉粥样硬化改变的女性主动脉以及无论有无动脉粥样硬化改变的男性主动脉相比，轻度动脉粥样硬化改变的女性主动脉获得的VSMC中STS表达水平显著更高。然而，这些主动脉VSMC中的EST表达水平在严重动脉粥样硬化改变的女性主动脉和男性主动脉中显著高于轻度动脉粥样硬化改变的女性主动脉。此外，轻度动脉粥样硬化的女性主动脉新生内膜中ERα和/或ERβ双阳性细胞的数量高于严重动脉粥样硬化的女性主动脉。它们表明女性主动脉中这些雌激素代谢酶的丰度以及女性新生内膜VSMC中ER的相对水平可能与动脉粥样硬化变化的状态有关。
