Background: Activatable near-infrared fluorescent (NIRF) probes have been used for ex vivo and in vivo detection of intestinal tumors in animal models. We hypothesized that NIRF probes activatable by cathepsins or metalloproteinases will detect and quantify dextran sulphate sodium (DSS)-induced acute colonic inflammation in wild type mice or chronic colitis in interleukin-10 (IL-10)–null mice ex vivo or in vivo.
Methods: Wild type mice given DSS, water controls, and IL-10–null mice with chronic colitis were administered probes by retro-orbital injection. FMT2500 LX system imaged fresh and fixed intestine ex vivo and mice in vivo. Inflammation detected by probes was verified by histology and colitis scoring. NIRF signal intensity was quantified using 2-dimensional region of interest ex vivo or 3-dimensional region of interest analysis in vivo.
Results: Ex vivo, 7 probes tested yielded significant higher NIRF signals in colon of DSS-treated mice versus controls. A subset of probes was tested in IL-10–null mice and yielded strong ex vivo signals. Ex vivo fluorescence signal with 680 series probes was preserved after formalin fixation. In DSS and IL-10–null models, ex vivo NIRF signal strongly and significantly correlated with colitis scores. In vivo, ProSense680, CatK680FAST, and MMPsense680 yielded significantly higher NIRF signals in DSS-treated mice than controls, but background was high in controls.
Conclusions: Both cathepsin or metalloproteinase-activated NIRF probes can detect and quantify colonic inflammation ex vivo. ProSense680 yielded the strongest signals in DSS colitis ex vivo and in vivo, but background remains a problem for in vivo quantification of colitis.
Article first published online 26 December 2013
*Department of Cell Biology and Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; and
†Division of Gastroenterology, Hepatology and Nutrition, School of Medicine, Vanderbilt University, Nashville, Tennessee.
Reprints: Shengli Ding, PhD, Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, 111 Mason Farm Road, MBRB, CB #7545, Chapel Hill, NC 27599-7545 (e-mail: firstname.lastname@example.org).
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Supported by DK047769, CA105417, and University Cancer Research Fund (UCRF).
The authors have no conflicts of interest to disclose.
Received October 23, 2013
Accepted November 19, 2013