Fluorescence Lifetime Imaging (FLIm): a method to evaluate colon inflammation in vivo

PROJECT SUMMARY/ABSTRACT
Inflammatory bowel disease (IBD) is an umbrella term for gastrointestinal (GI) diseases where chronic
inflammation and its sequelae significantly impact a patient’s physical health, quality of life, and healthcare
utilization. Early diagnosis of GI inflammation could prompt earlier medical intervention with a direct impact on
patient’s prognosis and quality of life. There is a need for novel methods capable of detecting early and low-
grade GI inflammation. The goal of this proposal is to demonstrate the feasibility of fluorescence lifetime imaging
(FLIm) for detecting early colorectal inflammation in vivo. Without requiring exogenous labeling agents, FLIm is
sensitive to changes in cellular metabolism, which is altered at the onset of inflammatory processes.
Our specific aims focus on establishing FLIm as a research tool to quantify and monitor inflammation at the
tissue level using the in vivo murine colon as a model. In Aim 1 we will (sub-aim 1.1) fabricate a side-viewing
endoscopic probe for nondestructive, in situ, and in vivo intraluminal imaging of the full length of the colon and
(sub-aim 1.2) show that FLIm is sensitive to epithelial metabolism using wild-type and PPAR-g knockout mice
treated with antibiotic (streptomycin) to generate transient dysbiosis and with 5-ASA to protect against antibiotic
effects. In Aim 2 we will test the relevance of FLIm for detecting early inflammatory changes with a model that
recapitulates aspects of pre-IBD (high-fat diet and antibiotics). Using image processing and statistical analysis,
we will validate the FLIm parameters with histopathology and biochemical assays (H&E, tissue hypoxia,
intracellular lactate, NAD+/NADH, ADP/ATP, PDH activity) performed after necropsy (n = 6 animals/group for
both male and female mice). The broad range of inflammatory responses generated with this study will
demonstrate the sensitivity of FLIm as a research tool for label-free, nondestructive, in vivo intraluminal detecting
and monitoring the host response to GI inflammation.
Results from this research are expected to provide convincing preliminary data for subsequent R01-type
research grant applications that build on the proposed concept. The long-term goal of the PI is to establish FLIm
as a nondestructive and label-free, in situ and in vivo, mesoscopic imaging modality to study 1) pathogenesis
and treatment of GI inflammation over time, 2) the host-microbiota relationship with pharmacological and dietary
changes, and 3) to translate this approach into a clinical tool for in vivo endoscopic imaging of the human GI
tract. We anticipate that the applications of the proposed implementation of FLIm range from early detection of
inflammatory and infectious diseases and cancer to the close monitoring of pharmacological and nutritional
treatments on the GI tract.

Grant Number: 5R21DK133773-03
NIH Institute/Center: NIH
Principal Investigator: Alba Alfonso-Garcia