Glucose is a major source of energy for most living organisms and its aberrant uptake is linked to many pathological conditions. However, our understanding of disease-associated glucose flux is limited due to the lack of robust tools. To date, positron emission tomography (PET) imaging remains the gold standard for measuring glucose uptake, and no optical tools exist for non-invasive longitudinal imaging of this important metabolite in in vivo settings. Here we report the development of a novel bioluminescent glucose uptake probe (BiGluc) for real-time, non-invasive longitudinal imaging of glucose absorption both in vitro and in vivo. In addition, we demonstrate that the sensitivity of our method is comparable with commonly used 18F-FDG-PET tracers and validate BiGluc as a tool for the identification of novel glucose transport inhibitors. The new imaging reagent enables a wide range of applications in the field of metabolism and drug development.
The microbiome-produced enzyme bile salt hydrolase (BSH) plays a central role in human health, but its function remains unclear due to the lack of suitable methods for measuring its activity. Here, we have developed a novel optical tool based on ultrasensitive bioluminescent imaging and demonstrated that this assay can be used for quick and cost-effective quantification of BSH activity across a broad range of biological settings including pure enzymes and bacteria, intact fecal slurries, and noninvasive imaging in live animals, as well as for the assessment of BSH activity in the entire gastrointestinal tract of mice and humans. Using this assay, we showed that certain types of prebiotics are capable of increasing BSH activity of the gut microbiota in vivo and successfully demonstrated potential application of this assay as a noninvasive diagnostic test to predict the clinical status of inflammatory bowel disease (IBD) patients.
Bioluminescent imaging (BLI) is one of the most powerful and widely used preclinical imaging modalities. However, the current technology relies on the use of transgenic luciferase-expressing cells and animals and therefore can only be applied to a limited number of existing animal models of human disease. Here, we report the development of a “portable bioluminescent” (PBL) technology that overcomes most of the major limitations of traditional BLI. We demonstrate that the PBL method is capable of noninvasive measuring the activity of both extracellular (e.g., dipeptidyl peptidase 4) and intracellular (e.g., cytochrome P450) enzymes in vivo in non-luciferase-expressing mice. Moreover, we successfully utilize PBL technology in dogs and human cadaver, paving the way for the translation of functional BLI to the noninvasive quantification of biological processes in large animals. The PBL methodology can be easily adapted for the noninvasive monitoring of a plethora of diseases across multiple species.
Introduction
Diagnosing prosthetic joint infection (PJI) poses significant
challenges, and current modalities are fraught with low sensitivity and/or
potential morbidity. Photoacoustic imaging (PAI) is a novel ultrasound-based
modality with potential for diagnosing PJI safely and noninvasively.
Materials
In an established preclinical mouse model of bioluminescent
Staphylococcus aureus PJI, fluorescent indocyanine
green (ICG) was conjugated to β-cyclodextrin (CDX-ICG) or
teicoplanin (Teic-ICG) and injected intravenously 1-week postoperatively.
Daily fluorescent imaging (FLI) and PAI were used to localize and quantify
tracer signals. Results were analyzed with 2-way ANOVA.
Results
Fluorescence clearly localized to the site of infection and was
significantly higher with Teic-ICG compared to CDX-ICG
(P=0.046) and ICG-alone (P=0.0087). With
PAI, the photoacoustic signal per volumetric analysis was substantially
higher and better visualized with Teic-ICG compared to CDX-ICG and
ICG-alone, and co-localized well with BLI /FLI.
Conclusion
Photoacoustic imaging can successfully localize PJI in this
proof-of-concept study and has shown potential for clinical translation in
orthopaedics.
The kidney’s inherent complexity has made identifying cell-specific pathways challenging, particularly when temporally associating them with the dynamic pathophysiology of acute kidney injury (AKI). Here, we combine renal cell-specific luciferase reporter mice using a chemoselective luciferin to guide the acquisition of cell-specific transcriptional changes in C57BL/6 background mice. Hydrogen peroxide generation, a common mechanism of tissue damage, was tracked using a peroxy-caged-luciferin to identify optimum time points for immunoprecipitation of labeled ribosomes for RNA-sequencing. Together, these tools revealed a profound impact of AKI on mitochondrial pathways in the collecting duct. In fact, targeting the mitochondria with an antioxidant, ameliorated not only hydrogen peroxide generation, but also significantly reduced oxidative stress and the expression of the AKI biomarker, LCN2. This integrative approach of coupling physiological imaging with transcriptomics and drug testing revealed how the collecting duct responds to AKI and opens new venues for cell-specific predictive monitoring and treatment.
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