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During the past decade, molecular imaging has emerged as a new and innovative field combining clinical endoscopy with methods prior used in basic science. Through the labeling of cellular targets with certain molecular probes and their subsequent detection with dedicated endoscopic devices, molecular imaging enables the visualization of single molecules or receptors during ongoing endoscopy. Early studies in the field have provided proof-of-principle that molecular imaging can improve visualization, or even unmask, previously unrecognized early dysplasia or cancer. Building on this, further studies then used molecular imaging for grading and detecting inflammation and inflammation associated cancer. Most recently, molecular imaging has been used to phenotype the expression of single receptors and targets of biological therapy and thereby enables molecular tissue profile in vivo. With this live molecular fingerprinting, molecular imaging can be used to guide expression-tailored individualized therapy, and due to the diversification of biological therapy in both cancer and intestinal inflammation, it can be expected that molecular imaging will gain further traction in the foreseeable future. Within this review, we first summarize the technical components commonly used for molecular imaging and then review preclinical and clinical studies and possible and evolving clinical applications on molecular imaging within the entire the GI tract.

Background: Endoscopic resection of dysplastic lesions in early stages of cancer reduces mortality rates and is recommended by many national guidelines throughout the world. Snare polypectomy and endoscopic mucosal resection (EMR) are established techniques of polyp removal. The advantages of these methods are their relatively short procedure times and acceptable complication rates. The latter include delayed bleeding in 0.9% and a perforation risk of 0.4–1.3%, depending on the size and location of the resected lesion. EMR is a recent modification of endoscopic resection. A limited number of studies suggest that larger lesions can be removed en bloc with low complication rates and short procedure times. Novel techniques such as endoscopic submucosal dissection (ESD) are used to enhance en bloc resection rates for larger, flat, or sessile lesions. Endoscopic full-thickness resection (EFTR) is employed for non-lifting lesions or those not easily amenable to resection. Procedures such as ESD or EFTR are emerging standards for lesions inaccessible to EMR techniques. Summary: Endoscopic treatment is now regarded as first-line therapy for benign lesions. Key Message: Endoscopic resection of dysplastic lesions or early stages of cancer is recommended. A plethora of different techniques can be used dependent on the lesions.

Inflammatory bowel diseases (IBD) are complex diseases. Epidemiological studies suggest rising incidences in industrialized countries. The article is based on a literature search in PubMed and is oriented on the current guidelines published by the European Crohn's and Colitis Organisation. IBD are characterized by chronic diarrhoea, abdominal pain and peranal haemorrhage. Extraintestinal manifestations commonly affect joints, skin, eyes and bile tracts. Early diagnosis and therapeutic intervention determine individual patient outcome. Medical treatment currently includes aminosalicylates, corticosteroids, thiopurines, calcineurin inhibitors and biologicals. IBDs require anti-inflammatory and if necessary immunosuppressive therapy. Due to extraintestinal complications and the possible need for surgical intervention, an interdisciplinary approach is important.

Wichtigstes Mittel fur die Diagnose eines Morbus Crohn und die Beurteilung der entzundlichen Aktivitat ist die Endoskopie mit histologischer Begutachtung. Da diese Methode aufwandig und oft problematisch ist, wurden in den letzten Jahren zunehmend nicht-invasive Methoden (fort)entwickelt. Hierbei spielen Biomarker eine bedeutende Rolle.

Die Colitis ulcerosa stellt oft ein schwerwiegendes Krankheitsbild dar, das die Lebensqualitat deutlich einschranken kann. Befallsmuster und Krankheitsaktivitat weisen den Weg zur optimalen medikamentosen Therapie. Eine adaquate Lebensqualitat und eine steroidfreie Remission sind realistische Ziele, ggf. auch eine Abheilung der mukosalen Entzundung. Chirurgische Interventionen mussen bei einigen Verlaufen rechtzeitig berucksichtigt werden.

Background Vedolizumab has emerged as an important pillar of treatment in inflammatory bowel disease (IBD). However, for unknown reasons, not all patients respond to therapy. Earlier clinical studies suggested decreased response rates in the highest compared with medium dosage groups. Interestingly, vedolizumab has been shown to inhibit the homing of both regulatory (Treg) and effector T (Teff) cells and previous data from our group suggested different effect sizes in both populations. Thus, we hypothesised that the non-linear exposure–efficacy correlation might be explained by dose-dependent differential effects of vedolizumab on Treg and Teff homing. Therefore, we studied functional effects of different vedolizumab exposure levels on Treg and Teff cell trafficking. Methods The α4β7 expression on different human T-cell subsets as well as the binding characteristics of vedolizumab to these cells at different exposure levels was analysed via flow cytometry. Functional effects of different vedolizumab concentrations on the adhesion of Tregs and Teffs to mucosal addressin cell adhesion molecule 1 (MAdCAM-1) were analysed using dynamic in vitro adhesion assays, transmigration assays and in vivo homing assays in a humanised mouse model. The in vivo binding of vedolizumab to Tregs and Teffs in patients receiving therapy was quantified and correlated with the corresponding serum levels. Results We found a preferential binding of vedolizumab to Tregs at an exposure with 0.4 µg/ml vedolizumab that shifted to a preferential binding to Teffs at an exposure with 10 µg/ml. Further increase of vedolizumab to 50 µg/ml led to equal binding to Tregs and Teffs (Figure 1). Consistently, at 10 µg/ml, dynamic adhesion of Tregs to MAdCAM-1 was increased compared with Teffs, but no difference was noted at 50 µg/ml. Additionally, a higher number of Treg compared with Teff cells were able to transmigrate in a MAdCAM-1-dependent manner at a concentration of 10 µg/ml vedolizumab. Preliminary data from homing experiments in a humanised mouse model and from IBD patients treated with vedolizumab support the notion that differential binding preferences depending on the exposure level can also be observed in vivo. Conclusion Our findings support a dose-dependent differential binding of vedolizumab to different T-cell subpopulations and suggest that an optimal ‘window’ of exposure exists, in which effects on Teffs predominate over Tregs. While offering a potential explanation for earlier findings in dose-ranging studies, our data might lay the basis for the establishment of individualised dose optimisation in IBD patients.

Background Interferons (IFNs) are immune-modulatory cytokines expressed by epithelial and mucosal cells in response to viral and bacterial infection. Just recently, we discovered a correlation between IFN-λ expression and disease activity, including small intestinal inflammation and Paneth cell dysfunction, in human Crohn’s disease patients. On a molecular level, we uncovered that IFN-λ mediates epithelial cell death, in particular, Paneth cell death by a programmed necrosis, dependent on STAT1 activation and controlled by caspase-8. These results suggested that IFN-λ can be considered as a pathogenic cytokine in Crohn′s ileitis and should be considered as a new and promising target for future therapeutic intervention for this particular subtype of IBD. Our central question is now by which pathways interferon-regulated programmed necrosis of epithelial cells contributes to intestinal inflammation and how these mechanisms could be targeted for future therapeutic intervention. Methods We use a mouse model for Crohn’s Disease like inflammation and Paneth cell death that has a specific deletion of Caspase-8 in intestinal epithelial cells (Casp8∆IEC). We stimulate small intestinal organoids derived from Casp8∆IEC mice with IFNs in vitro and we overexpress IFN-λ in these mice in vivo by hydrodynamic tail vein injection of an IFN-λ expression vector. Furthermore, we use JAK-inhibitors to impede pharmacologically cell death pathways in the pathogenesis of intestinal inflammation in vitro and in vivo. Results We uncovered that gene expression of the cell death mediators Mlkl and Caspase-8 is dependent on IFN-λ-mediated JAK-STAT1 signalling. The non-specific pan JAK-inhibitor Tofacitinib is able to attenuate gene expression of Mlkl and Caspase-8 in vitro as well as in vivo. It prevents non-apoptotic as well as apoptotic cell death of small intestinal organoids stimulated with IFN-λ and is sufficient to prevent small intestinal tissue destruction in Casp8∆IEC mice challenged with IFN-λ. Additionally, we use the selective JAK1-inhibitor Filgotinib to limit the targeted JAK-STAT signalling pathways to only JAK1-STAT1 signalling and thus reduce side effects of the inhibitor on other signalling pathways. This had a similar effect as Tofacitinib suggesting that IFN controls MLKL-mediated cell death via JAK1. Conclusion In summary, our results indicate that targeting IFN-λ-mediated JAK-STAT1 signalling by the small-molecules Tofacitinib and Filgotinib impedes induction of Mlkl and Caspase-8-mediated cell death pathways. Therefore, JAK1 inhibitors such as Filgotinib might represent a promising novel therapy that may be sufficient to achieve efficacy particularly in Crohn′s ileitis patients who display elevated IFN-l serum levels.

Background SB2 is a biosimilar infliximab approved for the treatment of inflammatory bowel disease (IBD) patients. These are the first prospective data investigating long-term efficacy, safety, and pharmacokinetics after switching from infliximab originator to biosimilar SB2 in IBD patients. Methods This is a prospective, observational cohort study of patients that underwent a switch from infliximab originator to biosimilar SB2 in 2017 as part of routine care at the outpatient Clinic for IBD at the University Hospital of Erlangen, Germany. Long-term safety and clinical effectiveness were recorded over a follow-up period of 18-months. Clinical disease activity was assessed by the Harvey–Bradshaw Index (HBI) in Crohn’s disease (CD) and the partial Mayo Score (pMS) in ulcerative colitis (UC) patients. C-reactive protein (CRP) was analyzed at every patient visit, and IFX trough-level (TL) and anti-IFX antibodies (ADA) were measured prior to every SB2 administration, using the Promonitor® tests. The occurrence of adverse events was registered at every patient visit. Results A total of 148 IBD patients (96 CD, 52 UC) was enrolled. The median duration of previous infliximab treatment before the switch was 29 months (range 1.0–110.0). Median disease activity in CD was an HBI of 3 (0–16) at switch (baseline), 2 (0–13) at month 6, 3 (0–15) at month 12 and 2.5 (0–11) at month 18. Median disease activity in UC was a pMS of 0 (0–6) at baseline, 1 (0–4) at month 6, 1 (0–4) at month 12 and 1 (0–5) at month 18. The median TL for all IBD patients was 6.3 mg/ml (0.1–33.7) at baseline, 5.0 mg/ml (0.1–34.3) at month 6, 6.3 mg/ml (0.1–35.8) at month 12 and 5.1 mg/ml (0.1–35.4) at month 18. CRP for all IBD patients was 2.2 mg/l (0.1–45.6) at baseline, 2.2 mg/l (0.1–90.4) at month 6, 2.3 mg/l (0.1–169.5) at month 12 and 2.7 mg/l (0.1–19.8) at month 18. In the 18-month follow-up period, 12/103 (11.7%) of patients who were ADA-negative at baseline developed ADA post-switch. Altogether, 40 (27%) IBD patients discontinued SB2 treatment during the 18-month follow-up period (4 anaphylaxis, 20 loss of response, 7 non-serious and 9 serious adverse events), 2 paused during pregnancy, 1 discontinued in clinical remission, 10 were lost to follow-up (7 change of physician, 3 unknown). Serious adverse events comprised 3 malignancies (breast and prostate carcinoma, neuroendocrine malignancy), 1 liver abscess and 5 intestinal surgical procedures (1 perforation, 1 ileus, and 3 stenoses). Conclusion Switching from IFX originator to biosimilar SB2 was not associated with an increase in disease activity. No clinically meaningful changes in IFX trough levels or immunogenicity were identified. Altogether, SB2 was well tolerated in a real-life setting.