|ZFIN ID: ZDB-PUB-141125-4|
In Vivo nonlinear optical imaging of immune responses: tissue injury and infection
Zeng, Y., Yan, B., Xu, J., Sun, Q., He, S., Jiang, J., Wen, Z., Qu, J.Y.
|Source:||Biophysical journal 107: 2436-43 (Journal)|
|Registered Authors:||Wen, Zilong|
|PubMed:||25418312 Full text @ Biophys. J.|
Zeng, Y., Yan, B., Xu, J., Sun, Q., He, S., Jiang, J., Wen, Z., Qu, J.Y. (2014) In Vivo nonlinear optical imaging of immune responses: tissue injury and infection. Biophysical journal. 107:2436-43.
ABSTRACTIn this study, we demonstrate a noninvasive imaging approach based on multimodal nonlinear optical microscopy to in vivo image the responses of immune cells (neutrophils) to the tissue injury and bacterial infection in a zebrafish model. Specifically, the second harmonic generation from myosin thick filaments in sarcomere enabled a clear visualization of the muscle injury and infection. Two-photon excited fluorescence was used to track the behavior of the neutrophils that were transgenically labeled by red fluorescent protein. The corresponding reduced nicotinamide adenine dinucleotide (NADH) two-photon excited fluorescence images revealed a detailed morphological transformation process of individual neutrophils during muscle tissue injury and bacterial infection. The analysis of time-resolved NADH signals from the neutrophils provided important biological insights of the cellular energy metabolism during the immune responses. We found a significant increase of free/protein-bound NADH ratios in activated neutrophils in bacterial-infected tissue. In this study, we also discovered that, under 720 nm excitation, two wild-type strains (DH5? and BL21) of bacteria Escherichia coli emitted distinct endogenous fluorescence of double-peak at ?450 and ?520 nm, respectively. We demonstrated that the double-peak fluorescence signal could be used to differentiate the E. coli from surrounding tissues of dominant NADH signals, and to achieve label-free tracking of E. coli bacteria in vivo.