In vivo imaging using fluorescent antibodies to tumor necrosis factor predicts therapeutic response in Crohn's disease

Advanced endoscopy imaging in inflammatory bowel diseases

BACKGROUND AND AIMS

Rapid assessment of mucosal inflammation is of crucial importance for the initial diagnosis and the assessment of mucosal healing in inflammatory bowel disease (IBD). Moreover, the identification of intraepithelial neoplasias in IBD is of key relevance for clinical management. Here, we systematically analyzed the utility of advanced endoscopic imaging techniques for optimized diagnosis in IBD.

METHODS

PubMed/Medline, Web of Knowledge, and Cochrane library were searched twice for diagnostic studies on advanced endoscopic imaging in IBD. Clinical and technical information was retrieved and subsequently analyzed. Main outcome parameters consisted of the quality of the results, adverse events, and diagnostic yield.

RESULTS

Fifty-six clinical studies with a total of 3296 patients were selected for final analysis. Filter technologies permitted a more detailed analysis of mucosal inflammation in IBD. In spite of substantial heterogeneity across studies, dye-based chromoendoscopy with targeted biopsy sampling yielded higher detection rates of intraepithelial neoplasias in ulcerative colitis as compared with white-light endoscopy with random biopsy sampling. Moreover, endocytoscopy and endomicroscopy allowed subsurface imaging of inflamed or neoplastic mucosa in IBD at subcellular resolution. Finally, endomicroscopy-aided molecular imaging enabled the identification of membrane-bound tumor necrosis factor on mucosal cells as a potential driver of disease activity in Crohn's disease. No relevant adverse events were reported.

CONCLUSIONS

Advanced endoscopic imaging technologies are feasible, safe, and partially effective tools for detailed diagnosis of mucosal inflammation and detection of neoplasias in IBD. Results obtained from these advanced techniques may provide a rational basis for individualized, optimized therapy for IBD patients.

The α4β1 Homing Pathway Is Essential for Ileal Homing of Crohn's Disease Effector T Cells In Vivo

BACKGROUND

The precise mechanisms controlling homing of T effector (Teff) cells to the inflamed gut in Crohn's disease (CD) are still unclear, and clinical outcome data from patients with inflammatory bowel disease treated with the anti-α4β7 integrin antibody vedolizumab suggest differences between ulcerative colitis and CD.

METHODS

Expression of homing molecules was studied with flow cytometry and immunohistochemistry. Their functional role was investigated in in vitro adhesion assays and in a humanized mouse model of T cell homing to the inflamed gut in vivo.

RESULTS

Despite in vitro blockade of CD Teff adhesion to mucosal vascular addressin cell adhesion molecule-1 (MadCAM-1) and in contrast to previous observations in ulcerative colitis, anti-α4β7 treatment did not result in reduced Teff cell homing to the colon in vivo. However, the integrin α4β1 was expressed in higher levels on Teffs from patients with CD compared with controls, while its expression in the peripheral blood declined, and its expression in the intestine increased during the course of clinical vedolizumab treatment. Consistently, adhesion of CD Teffs to vascular cell adhesion molecule-1 (VCAM-1) was blocked by inhibition of α4 and α4β1 in vitro. Moreover, in vivo homing of CD Teffs to the ileum was reduced by inhibition of α4 and α4β1 integrins, but not α4β7 integrins.

CONCLUSIONS

Our findings suggest that Teff cell homing to the ileum through the axis α4β1-VCAM-1 is an essential and nonredundant pathway in CD in vivo, possibly affecting efficacy of clinical treatment with antiadhesion compounds.

Current and Future Targets for Mucosal Healing in Inflammatory Bowel Disease

The induction and subsequent maintenance of mucosal healing has emerged as one of the central therapeutic goals in the management of patients with inflammatory bowel disease (IBD) (Crohn's disease and ulcerative colitis). Current and novel treatment options are assessed regarding their therapeutic efficacy on the basis of their ability to induce mucosal healing. However, there is still substantial debate about the precise definition of mucosal healing. Here, we will give an overview regarding the definitions of mucosal healing as well as its probable effects on long-term disease behavior and finally focus on current and potential therapeutic targets to achieve this therapeutic goal in IBD patients.

Top-down approach to biological therapy of Crohn's disease

INTRODUCTION

Crohn's disease (CD) is a chronic, immune-mediated condition with a potentially disabling and destructive course. Despite growing data on when to use a therapeutic 'top-down' strategy, clinical management of this complex disorder is still challenging. Currently, the discussion of 'top-down' strategy in CD mostly includes biological therapy alone or in combination. Areas covered: This article is based on a review of existing literature regarding the use of biological therapy in a 'top-down' approach for the treatment of Crohn's disease. The authors reviewed all the major databases including MEDLINE as well as DDW and ECCO abstracts, respectively. Expert opinion: A 'top-down' therapeutic approach in Crohn's disease is strongly supported by existing data in patients with several risk factors for a severe course of disease. Moreover, there is an increasing amount of published data recommending a more individualised therapeutic strategy to identify candidates for 'top-down' treatment, based on enhanced diagnostics using biomarkers. Emerging therapeutic approaches besides existing therapy concepts using biologicals may possibly redefine the 'top-down' therapeutic strategy for Crohn's disease in the future.

Light in diagnosis, therapy and surgery

Light and optical techniques have made profound impacts on modern medicine, with numerous lasers and optical devices being currently used in clinical practice to assess health and treat disease. Recent advances in biomedical optics have enabled increasingly sophisticated technologies — in particular those that integrate photonics with nanotechnology, biomaterials and genetic engineering. In this Review, we revisit the fundamentals of light–matter interactions, describe the applications of light in imaging, diagnosis, therapy and surgery, overview their clinical use, and discuss the promise of emerging light-based technologies.

Fluorescent chemical probes for accurate tumor diagnosis and targeting therapy

This review focuses on small molecular ligand-targeted fluorescent imaging probes and fluorescent theranostics, including their design strategies and applications in clinical tumor treatment.

The Role of Mast Cells in Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is one of the most common functional gastrointestinal disorders, but its treatment is unsatisfactory as its pathophysiology is multifactorial. The putative factors of IBS pathophysiology are visceral hypersensitivity and intestinal dysmotility, also including psychological factors, dysregulated gut-brain axis, intestinal microbiota alterations, impaired intestinal permeability, and mucosal immune alterations. Recently, mucosal immune alterations have received much attention with the role of mast cells in IBS. Mast cells are abundant in the intestines and function as intestinal gatekeepers at the interface between the luminal environment in the intestine and the internal milieu under the intestinal epithelium. As a gatekeeper at the interface, mast cells communicate with the adjacent cells such as epithelial, neuronal, and other immune cells throughout the mediators released when they themselves are activated. Many studies have suggested that mast cells play a role in the pathophysiology of IBS. This review will focus on studies of the role of mast cell in IBS and the limitations of studies and will also consider future directions.

Biomarkers in Search of Precision Medicine in IBD

The completion of the human genome project in 2003 represented a major scientific landmark, ushering in a new era with hopes and expectations of fresh insights into disease mechanisms and treatments. In inflammatory bowel disease (IBD), many important discoveries soon followed, notably the identification of >200 genetic susceptibility loci and characterization of the gut microbiome. As "big data", driven by advances in technology, becomes increasingly available and affordable, individuals with IBD and clinicians alike yearn for tangible outcomes from the promise of "precision medicine"-precise diagnosis, monitoring, and treatment. Here, we provide a commentary on the prospects and challenges of precision medicine and biomarkers in IBD. We focus on the three key areas where precision IBD will have the most impact: (1) disease susceptibility, activity, and behavior; (2) prediction of drug response and adverse effects; and (3) identification of subphenotypic mechanisms to facilitate drug discovery and selection of new treatments in IBD.

Molecular mechanism of action of anti-tumor necrosis factor antibodies in inflammatory bowel diseases

Anti-tumor necrosis factor (TNF) antibodies are successfully used in the therapy of inflammatory bowel diseases (IBD). However, the molecular mechanism of action of these agents is still a matter of debate. Apart from neutralization of TNF, influence on the intestinal barrier function, induction of apoptosis in mucosal immune cells, formation of regulatory macrophages as well as other immune modulating properties have been discussed as central features. Nevertheless, clinically effective anti-TNF antibodies were shown to differ in their mode-of-action in vivo and in vitro. Furthermore, the anti-TNF agent etanercept is effective in the treatment of rheumatoid arthritis but failed to induce clinical response in Crohn’s disease patients, suggesting different contributions of TNF in the pathogenesis of these inflammatory diseases. In the following, we will review different aspects regarding the mechanism of action of anti-TNF agents in general and analyze comparatively different effects of each anti-TNF agent such as TNF neutralization, modulation of the immune system, reverse signaling and induction of apoptosis. We discuss the relevance of the membrane-bound form of TNF compared to the soluble form for the immunopathogenesis of IBD. Furthermore, we review reports that could lead to personalized medicine approaches regarding treatment with anti-TNF antibodies in chronic intestinal inflammation, by predicting response to therapy.

An increase in serum tumour necrosis factor-α during anti-tumour necrosis factor-α therapy for Crohn's disease - A paradox or a predictive index?

BACKGROUND

Soluble tumour necrosis factor-α (sTNF-α) has been reported to increase in the course of anti-TNF-α therapy for rheumatoid and skin diseases.

AIMS

To assess changes in sTNF-α and clinical efficacy of anti-TNF-α agents in Crohn's disease (CD).

METHODS

Sixty-four patients on infliximab or adalimumab were analyzed. Clinical outcomes were assessed by using CD Activity Index after the induction therapy and at week 52. sTNF-α was measured before and after the induction therapy with high-sensitivity immunoassay.

RESULTS

In the majority of patients, sTNF-α increased significantly. Those with the greatest increase were more likely to experience long-term response, were more often treated with infliximab, had less frequently isolated small bowel CD, and tended to have sTNF-α levels at baseline that correlated with C-reactive protein.

CONCLUSIONS

Neutralization of sTNF-α does not seem to be critical for the efficacy of anti-TNF-α therapy in CD. Paradoxically - an increase in sTNF-α may reflect an ongoing process that is beneficial for the clinical outcome.

Advanced imaging in colonoscopy: contemporary approach to dysplasia surveillance in inflammatory bowel disease

Inflammatory bowel disease (IBD) (ulcerative colitis (UC) and Crohn's disease (CD)) is a chronic relapsing/remitting condition characterised by intestinal inflammation. One of the main concerns in patients with longstanding ulcerative and Crohn's colitis is development of colonic dysplasia and colorectal cancer (CRC), a risk higher than that of the general population. Colonoscopy surveillance programmes have been developed by major societies worldwide to improve early dysplasia detection and treatment, thus preventing progression to colorectal cancer. Colonoscopy is an imperfect tool as lesions can be missed, an issue even more relevant to colitic patients, where mucosal inspection and lesion recognition may prove challenging. Extensive research has been undertaken on performance improvement in this area while technical advances in optical imaging, such as high-definition, have made their way into modern endoscopy units. Techniques and technologies available to enhance optical diagnosis of dysplasia in inflammatory bowel disease are reviewed in this paper, focusing on those that are realistic, widely available and feasible for everyday practice.

Endomicroscopy and Molecular Tools to Evaluate Inflammatory Bowel Disease

Endoscopy is an essential tool for effective care of patients with inflammatory bowel disease (IBD), including Crohn disease and ulcerative colitis. The newest endoscopic small-field imaging technologies with confocal endomicroscopy have allowed real-time imaging of gastrointestinal mucosal during ongoing endoscopic evaluation and in vivo histology. Thus, endomicroscopy has a potential to further enhance the endoscopic evaluation of IBD. Advances in molecular in vivo imaging in IBD may be used not only to better understand the pathophysiology of IBD but also to guide optimized therapy and thus to allow a personalized, new approach to the IBD management.

Probe-Based Confocal Laser Endomicroscopy for Imaging TRAIL-Expressing Mesenchymal Stem Cells to Monitor Colon Xenograft Tumors In Vivo

Introduction

Mesenchymal stem cells (MSCs) can serve as vehicles for therapeutic genes. However, little is known about MSC behavior in vivo. Here, we demonstrated that probe-based confocal laser endomicroscopy (pCLE) can be used to track MSCs in vivo and individually monitor tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) gene expression within carcinomas.

Methods

Isolated BALB/c nu/nu mice MSCs (MSCs) were characterized and engineered to co-express the TRAIL and enhanced green fluorescent protein (EGFP) genes. The number of MSCs co-expressing EGFP and TRAIL (TRAIL-MSCs) at tumor sites was quantified with pCLE in vivo, while their presence was confirmed using immunofluorescence (IF) and quantitative polymerase chain reaction (qPCR). The therapeutic effects of TRAIL-MSCs were evaluated by measuring the volumes and weights of subcutaneous HT29-derived xenograft tumors.

Results

Intravital imaging of the subcutaneous xenograft tumors revealed that BALB/c mice treated with TRAIL-MSCs exhibited specific cellular signals, whereas no specific signals were observed in the control mice. The findings from the pCLE images were consistent with the IF and qPCR results.

Conclusion

The pCLE results indicated that endomicroscopy could effectively quantify injected MSCs that homed to subcutaneous xenograft tumor sites in vivo and correlated well with the therapeutic effects of the TRAIL gene. By applying pCLE for the in vivo monitoring of cellular trafficking, stem cell-based anticancer gene therapeutic approaches might be feasible and attractive options for individualized clinical treatments.

Molecular probing of TNF: From identification of therapeutic target to guidance of therapy in inflammatory diseases

Therapy by blocking tumor necrosis factor (TNF) activity is highly efficacious and profoundly changed the paradigm of several inflammatory diseases. However, a significant proportion of patients with inflammatory diseases do not respond to TNF inhibitors (TNFi). Prediction of therapeutic response is required for TNFi therapy. Isotope labeled anti-TNF antibodies or TNF receptor have been investigated to localize TNF production at inflammatory tissue in animal models and in patients with inflammatory diseases. The in vivo detection of TNF has been associated with treatment response. Recently, fluorophore labeled anti-TNF antibody in combination with confocal laser endomicroscopy in patients with Crohn's disease yielded more accurate and quantitative in vivo detection of TNF in the diseased mucosa. More importantly, this method demonstrated high therapeutic predication value. Fluorophore labeled TNF binding aptamers in combination with modern imaging technology offers additional tools for in vivo TNF probing.

Molecular endoscopy for targeted imaging in the digestive tract

Endoscopy uses optical imaging methods to investigate tissue in a non-destructive manner with high resolution over a broad range of wavelengths, thus providing a powerful tool to rapidly visualise mucosal surfaces in the digestive tract. Molecular imaging is an important advancement that has been clinically demonstrated for early cancer detection and guidance of therapy. With this approach, imaging can be used to observe expression patterns of molecular targets to improve understanding of key biological mechanisms that drive disease progression. Prototype devices that collect fluorescence for wide-field or microscopic images have been developed. Several targeting moieties, including enzyme-activatable probes, antibodies, peptides, and lectins, have been administered in preclinical and clinical imaging studies in vivo. These emerging technologies provide useful approaches to study molecular events in different signalling pathways, producing insights that could lead to improved interventions to prevent and treat gastrointestinal diseases. In this Review, we introduce the basic concepts that form the foundation for development of molecular endoscopy and summarise key results from preclinical and clinical studies.

Comprehensive phantom for interventional fluorescence molecular imaging

Fluorescence imaging has been considered for over a half-century as a modality that could assist surgical guidance and visualization. The administration of fluorescent molecules with sensitivity to disease biomarkers and their imaging using a fluorescence camera can outline pathophysiological parameters of tissue invisible to the human eye during operation. The advent of fluorescent agents that target specific cellular responses and molecular pathways of disease has facilitated the intraoperative identification of cancer with improved sensitivity and specificity over nonspecific fluorescent dyes that only outline the vascular system and enhanced permeability effects. With these new abilities come unique requirements for developing phantoms to calibrate imaging systems and algorithms. We briefly review herein progress with fluorescence phantoms employed to validate fluorescence imaging systems and results. We identify current limitations and discuss the level of phantom complexity that may be required for developing a universal strategy for fluorescence imaging calibration. Finally, we present a phantom design that could be used as a tool for interlaboratory system performance evaluation.

Advances in endoscopic imaging in ulcerative colitis

Modern strategies for the treatment of ulcerative colitis require more accurate tools for gastrointestinal imaging to better assess mucosal disease activity and long-term prognostic clinical outcomes. Recent advances in gastrointestinal luminal endoscopy are radically changing the role of endoscopy in every-day clinical practice and research trials. Advanced endoscopic imaging techniques including high-definition endoscopes, optical magnification endoscopy, and various chromoendoscopy techniques have remarkably improved endoscopic assessment of ulcerative colitis. More recently, optical biopsy techniques with either endocytoscopy or confocal laser endomicroscopy have shown great potential in predicting several histological changes in real time during ongoing endoscopy. Here, we review current applications of advanced endoscopic imaging techniques in ulcerative colitis and present the most promising upcoming headways in this field.

Mutation of cysteine 46 in IKK-beta increases inflammatory responses

Activation of IκB kinase β (IKK-β) and nuclear factor (NF)-κB signaling contributes to cancer pathogenesis and inflammatory disease; therefore, the IKK-β−NF-κB signaling pathway is a potential therapeutic target. Current drug design strategies focus on blocking NF-κB signaling by binding to specific cysteine residues on IKK-β. However, mutations in IKK-β have been found in patients who may eventually develop drug resistance. For these patients, a new generation of IKK-β inhibitors are required to provide novel treatment options. We demonstrate in vitro that cysteine-46 (Cys-46) is an essential residue for IKK-β kinase activity. We then validate the role of Cys-46 in the pathogenesis of inflammation using delayed-type hypersensitivity (DTH) and an IKK-β^C46A transgenic mouse model. We show that a novel IKK-β inhibitor, dihydromyricetin (DMY), has anti-inflammatory effects on WT DTH mice but not IKK-β^C46A transgenic mice. These findings reveal the role of Cys-46 in the promotion of inflammatory responses, and suggest that Cys-46 is a novel drug-binding site for the inhibition of IKK-β.

The many faces of FcγRI: implications for therapeutic antibody function

Fcγ receptor I (FcγRI or CD64) is the sole human Fc receptor with high affinity for monovalent IgG. While it contains an immunoreceptor tyrosine-based activation motif in its cytoplasmic domain, binding of FcγRI can result in a complex array of activating and inhibitory outcomes. For instance, binding of monomeric IgG provides a low-intensity tonic signal through FcγRI that is necessary for full interferon γ receptor signaling in the same cell. Interaction of FcγRI with larger high-avidity complexes can result in phagocytosis, the generation of reactive oxygen species, as well as the synthesis and release of inflammatory cytokines. However, numerous reports also document potent anti-inflammatory effects brought about by FcγRI engagement with immune complexes such as the inhibition of IFNγ and TLR4 signaling, and secretion of interleukin-10. This has led to conflicting hypotheses regarding the function of FcγRI, especially with regard to its role in the efficacy of several therapeutic monoclonal antibodies. While many of these issues are still unclear, continued characterization of the regulation and context dependence of FcγRI function, as well as the molecular mechanisms responsible for these various outcomes, will improve our understanding of FcγRI biology as well as the therapeutic strategies designed to harness or constrain its actions.

Two-photon excited fluorescence of intrinsic fluorophores enables label-free assessment of adipose tissue function

Current methods for evaluating adipose tissue function are destructive or have low spatial resolution. These limit our ability to assess dynamic changes and heterogeneous responses that occur in healthy or diseased subjects, or during treatment. Here, we demonstrate that intrinsic two-photon excited fluorescence enables functional imaging of adipocyte metabolism with subcellular resolution. Steady-state and time-resolved fluorescence from intracellular metabolic co-factors and lipid droplets can distinguish the functional states of excised white, brown, and cold-induced beige fat. Similar optical changes are identified when white and brown fat are assessed in vivo. Therefore, these studies establish the potential of non-invasive, high resolution, endogenous contrast, two-photon imaging to identify distinct adipose tissue types, monitor their functional state, and characterize heterogeneity of induced responses.

Imaging of intestinal fibrosis: current challenges and future methods

Crohn's disease (CD) activity assessments are dominated by inflammatory changes without discrete measurement of the coexisting fibrotic contribution to total bowel damage. Intestinal fibrosis impacts the development of severe structural complications and the overall natural history of CD. Measuring intestinal fibrosis is challenging and existing methods of disease assessment are unable to reliably distinguish fibrosis from inflammation. Both the immediate clinical need to measure fibrosis for therapeutic decision-making and the near-future need for tools to assess pipeline anti-fibrotic medications highlight the demand for biomarkers of fibrosis in CD. Developing non-invasive technologies exploit changes in intestinal perfusion, mechanical properties, and macromolecular content to provide quantitative markers of fibrosis. In this review of existing and experimental technologies for imaging intestinal fibrosis, we discuss the expanding capabilities of quantitative MR and ultrasound imaging, encouraging developments in non-invasive elastography, and emerging novel methods including photoacoustic imaging.

Optimizing Treatment with TNF Inhibitors in Inflammatory Bowel Disease by Monitoring Drug Levels and Antidrug Antibodies

BACKGROUND

Biological tumor necrosis factor (TNF) inhibitors have revolutionized the treatment of inflammatory bowel disease and redefined treatment goals to include mucosal healing. Clinicians are faced with challenges such as inadequate responses, treatment failures, side effects, and high drug costs. The objective is to review optimization of anti-TNF therapy by use of personalized treatment strategies based on circulating drug levels and antidrug antibodies (Abs), i.e. therapeutic drug monitoring (TDM). Furthermore, to outline TDM-related pitfalls and their prevention.

METHODS

Literature review.

RESULTS

Circulating anti-TNF drug trough level is a marker for the pharmacokinetics (PK) of TNF inhibitors. Because of a number of factors, including antidrug antibodies, PK varies between and within patients across time leading to variable clinical outcomes. Differences in intestinal inflammatory phenotype influencing the pharmacodynamic (PD) responses to TNF inhibitors also affect treatment outcomes. As an alternative to handling anti-TNF-treated patients by empiric strategies, TDM identifies underlying PK and PD-related reasons for treatment failure and aids decision making to secure optimal clinical and economic outcomes. Although promising, evidence does not the support use of TDM to counteract treatment failure in quiescent disease. Use of TDM is challenged by methodological biases, difficulties related to differentiation between PK and PD problems, and temporal biases due to lack of chronology between changes in PK versus symptomatic and objective disease activity manifestations. Biases can be accommodated by knowledgeable interpretation of results obtained by validated assays with clinically established thresholds, and by repeated assessments over time using complimentary techniques.

CONCLUSIONS

TDM-guided anti-TNF therapy at treatment failure has been brought from bench to bedside.

Light and sound - emerging imaging techniques for inflammatory bowel disease

Patients with inflammatory bowel disease are known to have a high demand of recurrent evaluation for therapy and disease activity. Further, the risk of developing cancer during the disease progression is increasing from year to year. New, mostly non-radiant, quick to perform and quantitative methods are challenging, conventional endoscopy with biopsy as gold standard. Especially, new physical imaging approaches utilizing light and sound waves have facilitated the development of advanced functional and molecular modalities. Besides these advantages they hold the promise to predict personalized therapeutic responses and to spare frequent invasive procedures. Within this article we highlight their potential for initial diagnosis, assessment of disease activity and surveillance of cancer development in established techniques and recent advances such as wide-view full-spectrum endoscopy, chromoendoscopy, autofluorescence endoscopy, endocytoscopy, confocal laser endoscopy, multiphoton endoscopy, molecular imaging endoscopy, B-mode and Doppler ultrasound, contrast-enhanced ultrasound, ultrasound molecular imaging, and elastography.

Considerations, challenges and future of anti-TNF therapy in treating inflammatory bowel disease

INTRODUCTION

Crohn's disease (CD) and ulcerative colitis (UC) are chronic disabling conditions. Monoclonal antibody therapy directed against tumor necrosis factor-alpha (anti-TNF) has revolutionized the care of patients with inflammatory bowel disease (IBD).

AREAS COVERED

Considerations before starting anti-TNF therapy are highlighted: the best time to start with anti-TNF therapy, either alone or in combination with an immunomodulator, the choice of an anti-TNF agent and the contra-indications to anti-TNF therapy. Primary nonresponse and secondary loss of response are discussed. De-escalating therapy, the role of therapeutic drug monitoring and the use of biosimilars, are handled. Finally, the future directions of anti-TNF therapy are emphasized.

EXPERT OPINION

Anti-TNF therapy remains the cornerstone in the treatment of IBD. When initiating long-term therapy, safety and cost issues are of great importance. The therapeutic armamentarium in the treatment of IBD is rapidly growing. Therefore, the challenge is to optimize the use and refine the exact position of anti-TNF therapy in the near future, with personalized medicine as the ultimate goal.

Predicting durable response or resistance to antitumor necrosis factor therapy in inflammatory bowel disease

Monoclonal antibodies to tumor necrosis factor (TNF) have become a mainstay of the therapeutic armamentarium in inflammatory bowel disease (IBD) over the last 15 years. Although highly effective, primary and secondary nonresponse are common and associated with poor clinical outcomes and significant costs. Multiple clinical, genetic and immunopharmacological factors may impact the response to anti-TNFs. Early stratification of IBD patients by the expected risk of therapeutic failure during the induction and maintenance phases of treatment may allow for treatment optimization and potentially optimal short- and long-term outcomes. The aim of this review is to summarize the current data concerning the potential predictors of therapeutic success and failure of anti-TNFs in IBD.

From bench to bedside: molecular imaging in inflammatory bowel diseases

PURPOSE OF REVIEW

Standard structural imaging procedures such as endoscopy, ultrasonography, or MRI are an integral part of the rational management of patients with inflammatory bowel diseases (IBDs). There is nevertheless the need for further refined imaging approaches that are able to overcome the limitations of currently used formats. The advent of molecular imaging modalities that allow real-time visualization of cellular processes not only in the preclinical setting but also in clinical trials has demonstrated its ability to improve current therapeutic strategies. The purpose of this review is to present and discuss advancements in the field of molecular imaging approaches in the IBD field.

RECENT FINDINGS

Recent preclinical and clinical studies have addressed the applicability of molecular imaging for improving the differentiation between benign and malignant mucosal alterations, increasing the detection of dysplastic intestinal lesions, and predicting individual responses to biological therapies.

SUMMARY

Molecular imaging in IBD represents an exciting and evolving field that has the potential to impact on current diagnostic and therapeutic algorithms in the treatment of IBD patients by analyzing and visualizing the molecular mechanisms that drive mucosal inflammation. It might enable us to base individualized therapeutic decisions on preceded molecular level analysis by suitable imaging modalities.

Predicting Therapeutic Response by in vivo Molecular Imaging in Inflammatory Bowel Diseases

BACKGROUND

Different invasive and non-invasive imaging modalities are indispensable tools in the management of inflammatory bowel disease (IBD) patients. Standard imaging procedures like white light endoscopy or MRI are used to define gut inflammation based on structural changes and altered morphology of the mucosa. Nevertheless, it has thus far not been possible to analyse biological processes at the cellular level, which drive intestinal inflammation in IBD patients. The recent advent of molecular imaging in the field of IBD has opened new promising avenues to allow personalized medicine approaches based on in vivo-detected molecular findings.

KEY MESSAGES

Recent clinical studies have attempted to address the issue of predicting therapeutic response to anti-tumor necrosis factor (TNF) treatment in IBD patients based on the molecular mechanism of action of these agents and corresponding in vivo assessment of mucosal immune responses. Several experimental studies have indicated that one of the main functions of efficacious anti-TNF therapy in IBD is the induction of intestinal cell apoptosis. Fittingly, a corresponding molecular-imaging study using single-photon emission CT for the localization and quantification of cell apoptosis, demonstrated that induction of mucosal T-cell apoptosis correlated with the therapeutic response to anti-TNF therapy in Crohn's disease patients. There was moreover a predictive capacity regarding therapeutic efficacy. As the main biological properties of anti-TNF antibodies in IBD are mediated through binding to membrane-bound TNF (mTNF) expressing intestinal cells, another study used molecular imaging for in vivo visualization of these cells via fluorescent anti-TNF antibodies to predict therapeutic efficacy of these agents. It could be shown that patients with high amounts of mTNF positive cells showed significantly better response rates compared to patients with low amounts of mTNF positive cells.

CONCLUSION

In vivo molecular imaging in IBD has the potential to have an impact on our current treatment approaches and may allow us to individualize specific therapies based on molecular level analysis.

TNF-Mediated Restriction of Arginase 1 Expression in Myeloid Cells Triggers Type 2 NO Synthase Activity at the Site of Infection

Neutralization or deletion of tumor necrosis factor (TNF) causes loss of control of intracellular pathogens in mice and humans, but the underlying mechanisms are incompletely understood. Here, we found that TNF antagonized alternative activation of macrophages and dendritic cells by IL-4. TNF inhibited IL-4-induced arginase 1 (Arg1) expression by decreasing histone acetylation, without affecting STAT6 phosphorylation and nuclear translocation. In Leishmania major-infected C57BL/6 wild-type mice, type 2 nitric oxide (NO) synthase (NOS2) was detected in inflammatory dendritic cells or macrophages, some of which co-expressed Arg1. In TNF-deficient mice, Arg1 was hyperexpressed, causing an impaired production of NO in situ. A similar phenotype was seen in L. major-infected BALB/c mice. Arg1 deletion in hematopoietic cells protected these mice from an otherwise lethal disease, although their disease-mediating T cell response (Th2, Treg) was maintained. Thus, deletion or TNF-mediated restriction of Arg1 unleashes the production of NO by NOS2, which is critical for pathogen control.

Cytokine-Induced Modulation of Colorectal Cancer

The emergence of novel immunomodulatory cancer therapies over the last decade, above all immune checkpoint blockade, has significantly advanced tumor treatment. For colorectal cancer (CRC), a novel scoring system based on the immune cell infiltration in tumors has greatly improved disease prognostic evaluation and guidance to more specific therapy. These findings underline the relevance of tumor immunology in the future handling and therapeutic approach of malignant disease. Inflammation can either promote or suppress CRC pathogenesis and inflammatory mediators, mainly cytokines, critically determine the pro- or anti-tumorigenic signals within the tumor environment. Here, we review the current knowledge on the cytokines known to be critically involved in CRC development and illustrate their mechanisms of action. We also highlight similarities and differences between CRC patients and murine models of CRC and point out cytokines with an ambivalent role for intestinal cancer. We also identify some of the future challenges in the field that should be addressed for the development of more effective immunomodulatory therapies.

How to Assess and Document Endoscopies in IBD Patients by Including Standard Scoring Systems

Endoscopy has become an essential tool for effective management of patients with inflammatory bowel disease, including Crohn's disease and ulcerative colitis. The endoscopic management of inflammatory bowel disease ranges from diagnosing the disease, assessing the disease's extent, and activity to monitor the responses to various medical therapies with assessment of mucosal healing, serving as a predictor of disease course and response to therapy to finally treating the disease's complications. In general, the use of endoscopic scoring systems has been recommended for assessing the activity of the disease, and the prognosis and efficacy of medical treatment. However, many of currently available endoscopic scoring systems are often too complicated for their routine use in clinical practice, lacking adequate interobserver agreement and formal validation. In this review, we will discuss how we should be assessing and documenting endoscopies in inflammatory bowel disease patients and incorporating standard scoring systems into patients' care.

Confocal Laser Endomicroscopy in Gastrointestinal and Pancreatobiliary Diseases: A Systematic Review and Meta-Analysis

Confocal laser endomicroscopy (CLE) is an endoscopic-assisted technique developed to obtain histopathological diagnoses of gastrointestinal and pancreatobiliary diseases in real time. The objective of this systematic review is to analyze the current literature on CLE and to evaluate the applicability and diagnostic yield of CLE in patients with gastrointestinal and pancreatobiliary diseases. A literature search was performed on MEDLINE, EMBASE, Scopus, and Cochrane Oral Health Group Specialized Register, using pertinent keywords without time limitations. Both prospective and retrospective clinical studies that evaluated the sensitivity, specificity, or accuracy of CLE were eligible for inclusion. Of 662 articles identified, 102 studies were included in the systematic review. The studies were conducted between 2004 and 2015 in 16 different countries. CLE demonstrated high sensitivity and specificity in the detection of dysplasia in Barrett's esophagus, gastric neoplasms and polyps, colorectal cancers in inflammatory bowel disease, malignant pancreatobiliary strictures, and pancreatic cysts. Although CLE has several promising applications, its use has been limited by its low availability, high cost, and need of specific operator training. Further clinical trials with a particular focus on cost-effectiveness and medicoeconomic analyses, as well as standardized institutional training, are advocated to implement CLE in routine clinical practice.

Pharmacological- and non-pharmacological therapeutic approaches in inflammatory bowel disease in adults

Inflammatory bowel diseases (IBDs) are a group of chronic inflammatory conditions mainly of the colon and small intestine. Crohn's disease (CD) and ulcerative colitis (UC) are the most frequent types of IBD. IBD is a complex disease which arises as a result of the interaction of environmental, genetic and immunological factors. It is increasingly thought that alterations of immunological reactions of the patients to their own enterable bacteria (microfilm) may contribute to inflammation. It is characterized by mucosal and sub mucosal inflammation, perpetuated by infiltration of activated leukocytes. CD may affect the whole gastrointestinal tract while UC only attacks the large intestine. The therapeutic goal is to achieve a steroid-free long lasting remission in both entities. UC has the possibility to be cured by a total colectomy, while CD never can be cured by any operation. A lifelong intake of drugs is mostly necessary and essential. Medical treatment of IBD has to be individualized to each patient and usually starts with anti-inflammatory drugs. The choice what kind of drugs and what route administered (oral, rectal, intravenous) depends on factors including the type, the localization, and severity of the patient's disease. IBD may require immune-suppression to control symptoms such as prednisolone, thiopurines, calcineurin or sometimes folic acid inhibitors or biologics like TNF-α inhibitors or anti-integrin antibodies. For both types of disease (CD, UC) the same drugs are available but they differ in their preference in efficacy between CD and UC as 5-aminosalicylic acid for UC or budesonide for ileocecal CD. As therapeutic alternative the main mediators of the disease, namely the activated pro-inflammatory cytokine producing leukocytes can be selectively removed via two apheresis systems (Adacolumn and Cellsorba) in steroid-refractory or dependent cases. Extracorporeal photopheresis results in an increase of regulatory B cells, regulatory CD8(+) T cells and T-regs Type 1. Both types of apheresis were able to induce clinical remission and mucosal healing accompanied by tapering of steroids.

Gastrointestinal imaging in 2015: Emerging trends in endoscopic imaging

Several key papers published in 2015 highlight important emerging trends in endoscopic imaging that promise to improve patient diagnosis and guidance of therapy. These studies reflect the future role for ‘smart’ contrast agents and fluorescence endoscopes to provide a molecular basis for disease detection, identify precancerous lesions and determine optimal choice of therapy.

Assessment of stricturing Crohn's disease: Current clinical practice and future avenues

Crohn’s disease (CD) is a chronic remittent idiopathic disease. Although the early phase of the disease is commonly characterized by inflammation-driven symptoms, such as diarrhea, the frequency of fibrostenotic complications in patients with CD increases over the long-term course of the disease. This review presents the current diagnostic options for assessing CD-associated strictures. In addition to the endoscopic evaluation of CD strictures, this review summarizes the currently available imaging modalities, including ultrasound and cross-sectional imaging techniques. In addition to stricture detection, differentiating between the primarily inflammatory strictures and the predominantly fibrotic ones is essential for selecting the appropriate treatment strategy (anti-inflammatory medical treatment vs endoscopical or surgical approaches). Therefore, recent imaging advances, such as contrast-enhanced ultrasound and ultrasound elastography, contribute to the development of non-invasive non-radiating imaging of CD-associated strictures. Finally, novel magnetic resonance imaging techniques, such as diffusion-weighted, motility and magnetization transfer imaging, as well as ¹⁸F-FDG PET/CT, molecular imaging approaches and biomarkers, are critically reviewed with regard to their potential role in assessing stricturing CD.

Advanced gastrointestinal endoscopic imaging for inflammatory bowel diseases

Gastrointestinal luminal endoscopy is of paramount importance for diagnosis, monitoring and dysplasia surveillance in patients with both, Crohn’s disease and ulcerative colitis. Moreover, with the recent recognition that mucosal healing is directly linked to the clinical outcome of patients with inflammatory bowel disorders, a growing demand exists for the precise, timely and detailed endoscopic assessment of superficial mucosal layer. Further, the novel field of molecular imaging has tremendously expanded the clinical utility and applications of modern endoscopy, now encompassing not only diagnosis, surveillance, and treatment but also the prediction of individual therapeutic responses. Within this review, we describe how novel endoscopic approaches and advanced endoscopic imaging methods such as high definition and high magnification endoscopy, dye-based and dye-less chromoendoscopy, confocal laser endomicroscopy, endocytoscopy and molecular imaging now allow for the precise and ultrastructural assessment of mucosal inflammation and describe the potential of these techniques for dysplasia detection.

Diagnostic imaging advances in murine models of colitis

Inflammatory bowel diseases (IBD) such as Crohn’s disease and ulcerative colitis are chronic-remittent inflammatory disorders of the gastrointestinal tract still evoking challenging clinical diagnostic and therapeutic situations. Murine models of experimental colitis are a vital component of research into human IBD concerning questions of its complex pathogenesis or the evaluation of potential new drugs. To monitor the course of colitis, to the present day, classical parameters like histological tissue alterations or analysis of mucosal cytokine/chemokine expression often require euthanasia of animals. Recent advances mean revolutionary non-invasive imaging techniques for in vivo murine colitis diagnostics are increasingly available. These novel and emerging imaging techniques not only allow direct visualization of intestinal inflammation, but also enable molecular imaging and targeting of specific alterations of the inflamed murine mucosa. For the first time, in vivo imaging techniques allow for longitudinal examinations and evaluation of intra-individual therapeutic response. This review discusses the latest developments in the different fields of ultrasound, molecularly targeted contrast agent ultrasound, fluorescence endoscopy, confocal laser endomicroscopy as well as tomographic imaging with magnetic resonance imaging, computed tomography and fluorescence-mediated tomography, discussing their individual limitations and potential future diagnostic applications in the management of human patients with IBD.

Pathway-based approaches to the treatment of inflammatory bowel disease

Crohn's disease and ulcerative colitis, collectively termed inflammatory bowel disease (IBD), are immunologic disorders that represent the prototypes of chronic intestinal inflammation. Their pathogenesis involves the dysregulated interaction between the intestinal microbiota and the gut-associated mucosal immune system that takes place when genetically predisposed individuals are exposed to detrimental environmental triggers. In recent years, the therapeutic dogma in IBD has shifted away from the administration of nonspecific immunosuppressives toward a pathway-based approach. In this review, we present an outlook of IBD treatment based on this new conceptual approach. Firstly, we will provide an overview of the major aspects of IBD pathogenesis with emphasis on specific pathway-based defects. Secondly, we will examine in detail the development of novel therapeutic approaches that can be used to target genetics, dysbiosis, the epithelial barrier, proinflammatory cytokines, and leukocyte trafficking. Most of these strategies are still in the developmental phase, but promising approaches include fecal microbiota transplantation as a means to correct IBD-related dysbiosis; administration of modified phosphatidylcholine to enhance the function of the intestinal mucous and tighten the defective epithelial barrier; the reduction of over-reactive proinflammatory pathways through the blockade of novel, nontumor necrosis factor inflammatory mediators via monoclonal antibodies against the common p40 chain of interleukin (IL-12) and IL-23, Janus kinase inhibitors, or antisense oligonucleotides against inhibitors of the immunosuppressive cytokine transforming growth factor-β1; and finally, inhibition of leukocyte trafficking to the gut via neutralization of the gut-specific α4β7 integrin. Availability of such diverse treatment modalities with specific pathway-based targets will increase the therapeutic options for patients with IBD.

Phenome-driven disease genetics prediction toward drug discovery

MOTIVATION

Discerning genetic contributions to diseases not only enhances our understanding of disease mechanisms, but also leads to translational opportunities for drug discovery. Recent computational approaches incorporate disease phenotypic similarities to improve the prediction power of disease gene discovery. However, most current studies used only one data source of human disease phenotype. We present an innovative and generic strategy for combining multiple different data sources of human disease phenotype and predicting disease-associated genes from integrated phenotypic and genomic data.

RESULTS

To demonstrate our approach, we explored a new phenotype database from biomedical ontologies and constructed Disease Manifestation Network (DMN). We combined DMN with mimMiner, which was a widely used phenotype database in disease gene prediction studies. Our approach achieved significantly improved performance over a baseline method, which used only one phenotype data source. In the leave-one-out cross-validation and de novo gene prediction analysis, our approach achieved the area under the curves of 90.7% and 90.3%, which are significantly higher than 84.2% (P < e(-4)) and 81.3% (P < e(-12)) for the baseline approach. We further demonstrated that our predicted genes have the translational potential in drug discovery. We used Crohn's disease as an example and ranked the candidate drugs based on the rank of drug targets. Our gene prediction approach prioritized druggable genes that are likely to be associated with Crohn's disease pathogenesis, and our rank of candidate drugs successfully prioritized the Food and Drug Administration-approved drugs for Crohn's disease. We also found literature evidence to support a number of drugs among the top 200 candidates. In summary, we demonstrated that a novel strategy combining unique disease phenotype data with system approaches can lead to rapid drug discovery.

AVAILABILITY AND IMPLEMENTATION

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CASE

edu/public/data/DMN

Optimizing biologic treatment in IBD: objective measures, but when, how and how often?

Background

The advent of biologic agents for the treatment of inflammatory bowel disease (IBD) was accompanied in parallel with emerging understanding of persisting underlying inflammation and ensuing bowel damage that can occur even in patients with seeming clinical remission. This lead to the concepts of mucosal healing and deep remission gaining acceptance as the more desired goals for therapy within an ambitious disease-control therapeutic approach, namely, treat-to-target strategy. However, how to practically monitor IBD patients, which objective measures to follow, at what time-points and whether to act upon results in asymptomatic patients are all questions that remain disputed.

Methods and result

In this concise review we aim to provide an overview of objective measures for monitoring of IBD patients, focusing on the challenging group of patients treated by infliximab, adalimumab, vedolizumab and other biologics. These objective measures are discussed in the context of the different common clinical scenarios wherein the clinician may contemplate their use. Specifically, we will delineate the role of objective parameters to be monitored during induction phase of treatment, during maintenance therapy, at loss of response and after elective cessation of therapy in patients in remission.

Conclusion

Coupled with the non-negligible costs of therapy, and the over-all worse prognosis of moderate-severe patients who are the usual recipients of biologic therapies, this challenging patients seem to be the first candidates for this more proactive strategy combining inflammatory and pharmacokinetic monitoring of objective inflammatory and pharmacokinetic measures. More data is still desirable to better define the exact parameters to be followed and their optimal thresholds, and to delineate the optimal cost-effective interventions for these patients.

New Insights into the Mechanisms of Action of Anti-Tumor Necrosis Factor-α Monoclonal Antibodies in Inflammatory Bowel Disease

Tumor necrosis factor alpha (TNF-α) has been widely accepted as a therapeutic target for inflammatory disorders including inflammatory bowel disease. Anti-TNF-α monoclonal antibodies (mAbs) including infliximab, adalimumab, golimumab, and certolizumab pegol have revolutionized therapy for these chronic inflammatory disorders. These agents are potent inhibitors of TNF-α, but significant evidence points to the fact that their actions extend beyond simple neutralization of the cytokine. Recent advances in understanding the mechanism of action of anti-TNF-α mAbs has discovered a number of previously unrecognized actions that are likely to be relevant in mediating their anti-inflammatory effects. Many of those actions are mediated by the binding of the antibodies to transmembrane TNF-α (tmTNF-α) and involve complex interactions with other molecular factors and cells. In this review, we have highlighted new information on the mechanism of actions of anti-TNF-α mAbs, from in vitro and in vivo studies. Despite obvious benefits in many patients, the clinical use of these antibodies are hampered by the fact that some patients do not respond to them, and among patients who do respond, many will develop recurrent disease despite continued dosing. Although pharmacokinetic factors explain some of the observed cases of partial or complete resistance to the effects of anti-TNF-α mAbs, other nonresponder patients may be resistant to those agents mechanism of action. A more thorough understanding of the mechanism of action of anti-TNF-α mAbs may allow the development of strategies to individualize therapy and to overcome resistance.

Confocal Laser Endomicroscopy in Inflammatory Bowel Disease--A Systematic Review

BACKGROUND AND AIMS

Confocal laser endomicroscopy is an endoscopic method that provides in vivo real-time imaging of the mucosa at a cellular level, elucidating mucosal changes that are undetectable by white light endoscopy. This paper systematically reviews current indications and perspectives of confocal laser endomicroscopy for inflammatory bowel disease.

METHODS

Available literature was searched systematically for studies applying confocal laser endomicroscopy in Crohn's disease or ulcerative colitis. Relevant literature was reviewed and only studies reporting original clinical data were included. Next, eligible studies were analysed with respect to several parameters, such as technique and clinical aim and definitions of outcomes.

RESULTS

Confocal laser endomicroscopy has been used for a wide range of purposes in inflammatory bowel disease, covering assessment of inflammatory severity, prediction of therapeutic response and relapse and adenoma surveillance in patients with ulcerative colitis. Methods for measurement of the histological changes ranged from subjective grading to objective quantification analysed by computer-aided models. The studies derived their conclusions from assessment of histological features such as colonic crypts, epithelial gaps and epithelial leakiness to fluorescein.

CONCLUSIONS

Confocal laser endomicroscopy remains an experimental but emerging tool for assessment of inflammatory bowel disease. It is the only method that enables in vivo functional assessment of intestinal barrier function. There is great heterogeneity in the literature and no single approach has been validated and reproduced to the level of general acceptance.

Endoscopic Therapy in Inflammatory Bowel Diseases

Background

Endoscopy is an essential diagnostic and therapeutic modality in the clinical care of inflammatory bowel disease (IBD) patients. Endoscopic therapy can be used for treatment of disease-related strictures, surveillance and resection of intraepithelial neoplasia, and treatment of fistulas or disease-related complications, and is currently being evaluated regarding its capacity in in vivo molecular imaging procedures.

Methods

A literature search using Medline and Science Citation Index was performed in March 2015. All studies on endoscopic therapy in IBD published from 1980 to 2015 (March) were reviewed. Potential studies were initially screened by title and abstract. The terms ‘endoscopy IBD’, ‘endoscopy therapy IBD’, ‘dilatation IBD’, ‘strictureplasty Crohn's disease’, ‘endoscopy therapy fistula’, ‘endoscopy toxic megacolon’, ‘endoscopy dysplasia IBD’, ‘endoscopy complications IBD’, and ‘molecular imaging IBD’ were used in the search. A total of 115 articles were studied to construct this review.

Results

Dilatation is most useful in short anastomotic strictures, but can be also undertaken in colonic strictures. Strictures in ulcerative colitis are always suspicious for neoplasia and should be evaluated carefully. Lesions with intraepithelial neoplasia can be resected when complete removal can be assured. The finding of carcinoma or high-grade dysplasia in a random biopsy is an indication for colectomy. If intraepithelial neoplasia is present in random biopsy specimens, colectomy should similarly be recommended. Endoscopic therapy of Crohn's fistulas is a possible emerging technology. In vivo molecular imaging is currently being studied in IBD patients and offers promising therapeutic opportunities.

Conclusion

Therapeutic endoscopy is indispensable in the management of IBD. It has to be carefully evaluated against alternative surgical options but often offers an effective therapeutic approach.

© 2015 S. Karger GmbH, Freiburg