We will test clinically approved antibodies targeting cytokine signaling or integrin-based homing of immune cells in the gut for their potential to allow endoscopic molecular in vivo imaging in ulcerative colitis patients. The GMP conform fluorescent antibodies will be applied to the inflamed mucosa of ulcerative colitis patients during endoscopic confocal laser endomicroscopy to decipher the molecular signature driving mucosal inflammation in individual patients. Such in vivo mapping of relevant inflammatory signaling pathways may allow the selection of the ideally suited neutralizing antibody for subsequent therapy and will thus open new avenues for personalized medicine in ulcerative colitis.