Institute of Biophotonics, National Yang-Ming University, 155 Linong Street, Section 2, Taipei 11221, Taiwan.
J Biomed Opt. 2012 Oct;17(10):101503. doi: 10.1117/1.JBO.17.10.101503.
Fluorescence lifetime imaging microscopy (FLIM) is a sensitive technique in monitoring functional and conformational states of nicotinamide adenine dinucleotide reduced (NADH) and flavin adenine dinucleotide (FAD),main compounds participating in oxidative phosphorylation in cells. In this study, we have applied FLIM to characterize the metabolic changes in HeLa cells upon bacterial infection and made comparison with the results from the cells treated with staurosporine (STS), a well-known apoptosis inducer. The evolving of NADH's average autofluorescence lifetime during the 3 h after infection with enterohemorragic Escherichia coli (EHEC) or STS treatment has been observed. The ratio of the short and the long lifetime components' relative contributions of NADH increases with time, a fact indicating cellular metabolic activity, such as a decrease of oxidative phosphorylation over the course of infection, while opposite dynamics is observed in FAD. Being associated with mitochondria, FAD lifetimes and redox ratio could indicate heterogeneous mitochondrial function, microenvironment with bacterial infection, and further pathway to cell death. The redox ratios for both EHEC-infected and STS-treated HeLa cells have been observed and these observations also indicate possible apoptosis induced by bacterial infection.
荧光寿命成像显微镜（FLIM）是一种监测烟酰胺腺嘌呤二核苷酸还原（NADH）和黄素腺嘌呤二核苷酸（FAD）等参与细胞氧化磷酸化的主要化合物的功能和构象状态的敏感技术。在这项研究中，我们应用 FLIM 来描述细菌感染后 HeLa 细胞的代谢变化，并与用星形孢菌素（STS）处理的细胞的结果进行比较，STS 是一种众所周知的凋亡诱导剂。观察到在感染肠出血性大肠杆菌（EHEC）或 STS 处理后 3 小时内 NADH 平均自发荧光寿命的演变。NADH 的短寿命和长寿命成分的相对贡献的比值随时间增加，这一事实表明细胞代谢活性，例如感染过程中氧化磷酸化的减少，而 FAD 则观察到相反的动态。与线粒体相关的 FAD 寿命和氧化还原比可以指示异质性线粒体功能、细菌感染的微环境以及进一步的细胞死亡途径。观察到了 EHEC 感染和 STS 处理的 HeLa 细胞的氧化还原比，这些观察结果也表明细菌感染可能诱导凋亡。
