Department of Chemical Engineering, Imperial College London, London, UK SW7 2AZ.
Analyst. 2009 Jun;134(6):1107-18. doi: 10.1039/b821425e. Epub 2009 Apr 2.
Inducible nitric oxide synthase (iNOS) has previously been shown to contribute to atherosclerotic lesion formation and protein nitration. Micro attenuated total reflection (ATR)-Fourier transform infrared (FTIR) spectroscopic imaging was applied ex vivo to analyse lesions in atherosclerotic (ApoE-/-) mice. Histologies of cardiovascular tissue of ApoE-/- mice that contain the gene for iNOS and ApoE-/- mice without iNOS (ApoE-/-iNOS-/- mice) were examined. Spectroscopic imaging of the aortic root revealed that iNOS did not affect the composition of the tunica media; furthermore, irrespective of iNOS presence, lipid esters were found to form the atherosclerotic plaque. ApoE-/- mouse aortic root lesions exhibited a more bulky atheroma that extended into the medial layer; signals characteristic of triglycerides and free fatty acids were apparent here. In ApoE-/-iNOS-/- mouse specimens, lesions composed of free cholesterol were revealed. ATR-FTIR spectra of the intimal plaque from the two mouse strains showed higher lipid concentrations in ApoE-/- mice, indicating that iNOS contributes to lesion formation. The reduction of lesion prevalence in ApoE-/-iNOS-/- mice compared with ApoE-/- mice is consistent with previous data. Moreover, the analysis of the plaque region revealed a change in the spectral position of the amide I band, which may be indicative of protein nitration in the ApoE-/- mouse, correlating with a more ordered (beta-sheet) structure, while a less ordered structure was apparent for the ApoE-/-iNOS-/- mouse, in which protein nitration is attenuated. These results indicate that micro ATR-FTIR spectroscopic imaging with high spatial resolution is a valuable tool for investigating differences in the structure and chemical composition of atherosclerotic lesions of ApoE-/- and ApoE-/-iNOS-/- mice fed a high-fat Western diet and can therefore be applied successfully to the study of mouse models of atherosclerosis.
诱导型一氧化氮合酶 (iNOS) 先前被证明有助于动脉粥样硬化病变的形成和蛋白质硝化。应用微衰减全反射 (ATR)-傅里叶变换红外 (FTIR) 光谱成像技术对动脉粥样硬化 (ApoE-/-) 小鼠的病变进行了分析。对 ApoE-/-小鼠的心血管组织进行了组织学检查，这些小鼠携带 iNOS 基因，而另一些则不携带 iNOS (ApoE-/-iNOS-/-小鼠)。对主动脉根部的光谱成像显示，iNOS 并不影响中膜的组成；此外，无论是否存在 iNOS，都发现脂质酯形成了动脉粥样硬化斑块。ApoE-/- 小鼠主动脉根部病变表现出更大量的动脉粥样硬化，延伸到中膜；这里可以明显看到甘油三酯和游离脂肪酸的信号。在 ApoE-/-iNOS-/-小鼠标本中，发现了由游离胆固醇组成的病变。两种小鼠品系内膜斑块的 ATR-FTIR 光谱显示，ApoE-/- 小鼠的脂质浓度更高，表明 iNOS 有助于病变的形成。与 ApoE-/- 小鼠相比，ApoE-/-iNOS-/- 小鼠的病变发生率降低，这与先前的数据一致。此外，对斑块区域的分析显示酰胺 I 带的光谱位置发生了变化，这可能表明 ApoE-/- 小鼠中的蛋白质硝化，与更有序的 (β-折叠) 结构相关，而 ApoE-/-iNOS-/- 小鼠中则出现了较少的有序结构，其中蛋白质硝化被减弱。这些结果表明，高空间分辨率的微 ATR-FTIR 光谱成像技术是研究高脂西方饮食喂养的 ApoE-/- 和 ApoE-/-iNOS-/- 小鼠动脉粥样硬化病变结构和化学成分差异的一种有价值的工具，因此可以成功应用于动脉粥样硬化小鼠模型的研究。
