Inflammatory bowel disease (IBD) and psoriasis (Ps) are common, chronic, immune- mediated barrier diseases with shared inflammatory pathways. Current therapeutic interventions with anti-cytokine antibodies (TNF-α, IL-23/IL-12) reflect the intent to disrupt specific pathways of inflammatory immunopathology. Individual responses to biological treatment can be thereby be exploited in a systems biology approach that employs a targeted mechanism of action (MOA) to decipher molecular signatures of therapeutic responses in the context of a distinct disease entity. Using a translational approach to investigate clinical and molecular phenotypes during therapeutic interference with cytokine signaling and leukocyte trafficking, the investigators aim to trace common and unique signatures of drug- and therapy-specific responses.||Patients will undergo endoscopic evaluation of the mucosal surface and gastrointestinal wall by conventional HD-colonoscopy, endoscopic ultrasound and confocal laser endomicroscopy prior to and during specific therapies with biologicals. In parallel, mucosa samples will be obtained to define molecular phenotypes during the course of therapy.