Molecular Endoscopy and in vivo Imaging in Inflammatory Bowel Diseases

Abstract

Background: Studies in recent years have shown that standard imaging modalities such as endoscopy, ultrasonography or MRI are essential for assessment of gut inflammation in patients with inflammatory bowel diseases (IBDs). In addition, endoscopy plays a pivotal role in the analysis of mucosal healing in these disorders. However, these techniques do not allow a detailed analysis of the molecular pathways driving gut inflammation in IBD patients. Here, we discuss the role of new techniques for the molecular imaging of gut inflammation in IBD with special reference to the prediction of responses to therapy using antibodies to tumor necrosis factor (anti-TNF). Key Messages: Several in vivo imaging studies have been performed in IBD patients before and after anti-TNF therapy. In one study, (99m)Technetium-labeled annexin V was given to patients with active Crohn's disease before and after anti-TNF therapy with infliximab. Subsequently, single-photon emission CT (SPECT) was performed to study the effect of anti-TNF treatment on apoptosis in the intestine during active colitis. This study showed enrichment of technetium signals in the gut of patients who responded to anti-TNF therapy. The findings suggested that anti-TNF treatment induces T-cell apoptosis in vivo and that SPECT imaging can be used for prediction of response to anti-TNF therapy. In another study, fluorescent anti-TNF antibodies (fluorescent adalimumab) were chosen for molecular imaging during confocal laser endomicroscopy in patients with active Crohn's disease. This study revealed that an increase of membrane-bound TNF expressing mucosal immune cells predicts response to subsequent adalimumab therapy. Conclusions: Molecular in vivo imaging is an exciting new field in patients with IBD. It is expected that this field will allow new insights into the pathophysiology of IBD and may be used for personalized medicine in the future.