Department of Mechanical, Manufacturing and Biomedical Engineering, Trinity College Dublin, Dublin, Ireland.
Trinity Centre for Biomedical Engineering, Trinity Biomedical Science Institute, Trinity College Dublin, Dublin, Ireland.
Elife. 2022 Oct 18;11:e77373. doi: 10.7554/eLife.77373.
In this study, we utilise fluorescence lifetime imaging of NAD(P)H-based cellular autofluorescence as a non-invasive modality to classify two contrasting states of human macrophages by proxy of their governing metabolic state. Macrophages derived from human blood-circulating monocytes were polarised using established protocols and metabolically challenged using small molecules to validate their responding metabolic actions in extracellular acidification and oxygen consumption. Large field-of-view images of individual polarised macrophages were obtained using fluorescence lifetime imaging microscopy (FLIM). These were challenged in real time with small-molecule perturbations of metabolism during imaging. We uncovered FLIM parameters that are pronounced under the action of carbonyl cyanide-p-trifluoromethoxyphenylhydrazone (FCCP), which strongly stratifies the phenotype of polarised human macrophages; however, this performance is impacted by donor variability when analysing the data at a single-cell level. The stratification and parameters emanating from a full field-of-view and single-cell FLIM approach serve as the basis for machine learning models. Applying a random forests model, we identify three strongly governing FLIM parameters, achieving an area under the receiver operating characteristics curve (ROC-AUC) value of 0.944 and out-of-bag (OBB) error rate of 16.67% when classifying human macrophages in a full field-of-view image. To conclude, 2P-FLIM with the integration of machine learning models is showed to be a powerful technique for analysis of both human macrophage metabolism and polarisation at full FoV and single-cell level.
在这项研究中,我们利用基于 NAD(P)H 的细胞内荧光寿命成像作为一种非侵入性的方法,通过其主导的代谢状态来间接区分两种截然不同的人类巨噬细胞状态。使用已建立的方案从人循环血液单核细胞中衍生的巨噬细胞进行极化,并使用小分子进行代谢挑战,以验证它们在细胞外酸化和耗氧方面的反应代谢作用。使用荧光寿命成像显微镜(FLIM)获得单个极化巨噬细胞的大视场图像。在成像过程中,这些细胞实时受到代谢小分子扰动的挑战。我们发现了在羰基氰化物-p-三氟甲氧基苯腙(FCCP)作用下表现明显的 FLIM 参数,这些参数强烈分层极化的人类巨噬细胞表型;然而,当在单细胞水平分析数据时,这种性能受到供体变异性的影响。全视场和单细胞 FLIM 方法得出的分层和参数可作为机器学习模型的基础。应用随机森林模型,我们确定了三个具有较强控制作用的 FLIM 参数,在全视场图像中对人类巨噬细胞进行分类时,接收器操作特性曲线(ROC-AUC)值达到 0.944,袋外(OBB)错误率为 16.67%。总之,2P-FLIM 与机器学习模型的结合被证明是一种强大的技术,可用于分析全视场和单细胞水平的人类巨噬细胞代谢和极化。