P009 Fluorescence mediated tomography detects and quantifies early intestinal neutrophil infiltration in experimental colitis
T. M. Nowacki*1,2, P. Lenz3, D. Bettenworth2, M. Brückner2, P. Tepasse2, A. Becker4, M. Wildgruber4, M. Eisenblätter4
1Josephs-Hospital Warendorf, Department of Medicine I, Warendorf, Germany, 2University Hospital Münster, Department of Medicine B, Gastroenterology and Hepatology, Münster, Germany, 3University Hospital Münster, Institute of Palliative Care, Münster, Germany, 4University Hospital Münster, Translational Research Imaging Center, Department of Clinical Radiology, Münster, Germany
Recruitment, infiltration, and activation of inflammatory cells are crucial steps in the pathogenesis of IBD. The aim of this study was the visualisation of these processes
Colitis was induced in C57BL/6 WT mice fed with 2.5% (w/v) dextran sodium sulphate (DSS) in their drinking water. Animals were monitored for weight loss and presence of blood in the stools by hemoccult testing. Intestinal neutrophil infiltration was measured by targeted fluorescence mediated tomography (FMT) after injection of a neutrophil-specific fluorescence labelled (Cyanine7, λexcitation: 750 nm, λemission: 776 nm) rat-anti-mouse Gr1 antibody or unspecific isotype control. FMT examinations and additional white light and fluorescence endoscopy were performed before (Day 0) and during (Day 5) colitis induction as well as at the end of the experiment (Day 10). Distribution of inflammatory cells in peripheral blood samples was determined by FACS staining for CD11b and Ly6C.
Colitic animals showed decreasing body weight and faecal occult blood. FMT revealed a significantly increased level of fluorescence only 5 days after colitis induction when compared with pre-experiment healthy conditions (738.6 pmol tracer vs. 73.2 pmol tracer;
Gr1-targeted FMT can detect early colonic infiltration of inflammatory neutrophils before clinical symptoms or endoscopic alterations occur.