Medical Devices Research Centre, National Research Council Canada , Winnipeg, Manitoba , Canada.
Department of Electrical and Computer Engineering, University of Manitoba , Winnipeg, Manitoba , Canada.
J Appl Physiol (1985). 2019 Mar 1;126(3):638-646. doi: 10.1152/japplphysiol.00497.2018. Epub 2019 Jan 10.
Structural proteins like collagen and elastin are major constituents of the extracellular matrix (ECM). ECM degradation and remodeling in diseases significantly impact the microorganization of these structural proteins. Therefore, tracking the changes of collagen and elastin fiber morphological features within ECM impacted by disease progression could provide valuable insight into pathological processes such as tissue fibrosis and atherosclerosis. Benefiting from its intrinsic high-resolution imaging power and superior biochemical specificity, nonlinear optical microscopy (NLOM) is capable of providing information critical to the understanding of ECM remodeling. In this study, alterations of structural fibrillar proteins such as collagen and elastin in arteries excised from atherosclerotic rabbits were assessed by the combination of NLOM images and textural analysis methods such as fractal dimension (FD) and directional analysis (DA). FD and DA were tested for their performance in tracking the changes of extracellular elastin and fibrillar collagen remodeling resulting from atherosclerosis progression/aging. Although other methods of image analysis to study the organization of elastin and collagen structures have been reported, the simplified calculations of FD and DA presented in this work prove that they are viable strategies for extracting and analyzing fiber-related morphology from disease-impacted tissues. Furthermore, this study also demonstrates the potential utility of FD and DA in studying ECM remodeling caused by other pathological processes such as respiratory diseases, several skin conditions, or even cancer. NEW & NOTEWORTHY Textural analyses such as fractal dimension (FD) and directional analysis (DA) are straightforward and computationally viable strategies to extract fiber-related morphological data from optical images. Therefore, objective, quantitative, and automated characterization of protein fiber morphology in extracellular matrix can be realized by using these methods in combination with digital imaging techniques such as nonlinear optical microscopy (NLOM), a highly effective visualization tool for fibrillar collagen and elastic network. Combining FD and DA with NLOM is an innovative approach to track alterations of structural fibrillar proteins. The results illustrated in this study not only prove the effectiveness of FD and DA methods in extracellular protein characterization but also demonstrate their potential value in clinical and basic biomedical research where protein microstructure characterization is critical.
结构蛋白，如胶原蛋白和弹性蛋白，是细胞外基质（ECM）的主要成分。疾病中 ECM 的降解和重塑会显著影响这些结构蛋白的微结构。因此，跟踪疾病进展过程中 ECM 中胶原蛋白和弹性纤维形态特征的变化，可以为组织纤维化和动脉粥样硬化等病理过程提供有价值的见解。受益于其固有的高分辨率成像能力和优异的生化特异性，非线性光学显微镜（NLOM）能够提供对 ECM 重塑的理解至关重要的信息。在这项研究中，通过 NLOM 图像和分形维数（FD）和方向分析（DA）等纹理分析方法相结合，评估了从动脉粥样硬化兔子中取出的动脉中结构纤维状蛋白（如胶原蛋白和弹性蛋白）的变化。FD 和 DA 用于跟踪动脉粥样硬化进展/老化引起的细胞外弹性蛋白和纤维状胶原蛋白重塑的变化。尽管已经报道了其他用于研究弹性蛋白和胶原蛋白结构组织的图像分析方法，但本工作中提出的 FD 和 DA 的简化计算证明了它们是从受疾病影响的组织中提取和分析纤维相关形态的可行策略。此外，本研究还证明了 FD 和 DA 在研究由其他病理过程（如呼吸道疾病、几种皮肤状况甚至癌症）引起的 ECM 重塑方面的潜在用途。
分形维数（FD）和方向分析（DA）等纹理分析是从光学图像中提取纤维相关形态数据的简单且可行的计算策略。因此，通过将这些方法与非线性光学显微镜（NLOM）等数字成像技术结合使用，可以实现对细胞外基质中蛋白质纤维形态的客观、定量和自动描述，NLOM 是纤维状胶原蛋白和弹性网络的高效可视化工具。将 FD 和 DA 与 NLOM 结合是跟踪结构纤维状蛋白变化的一种创新方法。本研究的结果不仅证明了 FD 和 DA 方法在细胞外蛋白质特征描述中的有效性，还证明了它们在临床和基础生物医学研究中的潜在价值，在这些研究中，蛋白质微结构特征描述至关重要。
