Background and aims. Inflammatory Bowel Disease (IBD) is characterised by overt inflammation of the lower gastrointestinal tract. It is typically diagnosed by colonoscopy which is an invasive procedure that requires extensive bowel preparation. As such, development of non-invasive technologies for the detection of colonic inflammation would greatly aid diagnosis and management of IBD. Dextran Sodium Sulphate (DSS) has been used extensively to model IBD providing important insights into the immune responses in colitis. We aimed to visualise colitis in-vivo using the glucose analogue 18F-FDG.
Methodology. Acute colitis was induced in male mice by adding 2% (w/v) DSS in drinking water for 5 days followed by 3 days of normal water and was compared against age and sex matched healthy male mice. Colonic concentrations of IL-1β, IL-6, GM-CSF and CXCL1 were analysed by multiplex. Colonic and splenic innate immune cell populations (CD3- CD11b+ CD11c-) were analysed by flow cytometry. 18F-FDG (10-15 MBq) was administered IV into anaesthetised mice and 18F-FDG PET scans were performed using an Albira PET-SPECT small animal scanner.
Results. Acute administration of DSS caused significant weight loss, shortening of the colon and increased MPO activity. Colonic concentrations of IL-1b, IL-6, GM-CSF and CXCL1 and proportions of splenic and colonic CD3- CD11b+CD11c- myeloid cells increased during acute colitis. Colonic uptake of 18F-FDG was greater in acute colitis when compared with health.
Conclusion. Acute murine DSS colitis activates the innate immune system. 18F-FDG is an effective means of visualising intestinal inflammation during acute DSS colitis. More studies adapting this technology, with more selective markers are warranted.