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

Endomicroscopy with Fluorescent CD105 Antibodies for "In Vivo" Imaging of Colorectal Cancer Angiogenesis

The aim of this case report was to evaluate the feasibility of in vivo acquisition of microscopic images using fluorescent CD105 antibodies for molecular imaging in human colorectal cancer. After excluding the presence of tissue autofluorescence, the antibody solution was topically administered through a spray-catheter. The targeted area was analyzed by eCLE and images were recorded. The fractal dimension of tumor vessels and the vessel density were determined using ImageJ software. Immunohistochemistry was used as a gold standard. In vivo CLE analysis of CD105 expression enabled the study of tumor vascular network, revealing a chaotic structure.

Cultured blood T-cell responses predict anti-TNF therapy response in patients with ulcerative colitis

BACKGROUND

Anti-tumour necrosis factor (TNF) therapy is used for treatment of ulcerative colitis (UC). As approximately 30% of patients with UC do not benefit from the treatment, it is of clinical interest to identify biomarkers of response before therapy is initiated.

AIM

To identify prognostic biomarkers of anti-TNF therapy response in anti-TNF therapy-naïve patients with UC.

METHODS

Peripheral blood cells were obtained from 56 patients with UC before therapy started. Thirty-four patients were included in an exploratory cohort and 22 patients in a validation cohort. Blood cells were stimulated in vitro with influenza vaccine with and without anti-TNF. T-cell surface receptor expression and cytokine release were determined (in total 17 variables). Treatment response was evaluated using the Mayo score 12-14 weeks after the first infusion.

RESULTS

In the exploratory cohort, blood cells from the patients showed stronger anti-TNF-dependent suppression of T-cell surface receptor expression and cytokine secretion among therapy responders than nonresponders. In particular, anti-TNF suppressed the expression of CD25 on T cells and secretion of interleukin 5, to a higher degree in responders than in nonresponders. These variables were used to a create model to predict therapy outcome, which was confirmed in the validation cohort. Correct classification of future therapy response was achieved in 91% of the cases in the validation cohort.

CONCLUSION

The effects of anti-TNF on cultured blood T cells, obtained before therapy started, predict treatment outcome in patients with UC.

Advances in imaging to allow personalized medicine in Crohn's disease

Crohn's disease is a destructive inflammatory bowel disease of unknown origin that may lead to various complications such as strictures, stenosis, fistulas and colitis-associated neoplasias. However, the course of the disease varies substantially among patients and disease behaviour may also change with time. At diagnosis behaviour is inflammatory in the majority of patients, while penetrating or structuring behaviour become more prominent at later time points. Thus, medication in Crohn's disease needs frequent optimization over time. Therefore, new strategies for prediction of response to therapy are urgently needed. Here, recent advantages in imaging techniques for personalized medicine in Crohn's disease are reviewed. Such advantages include ultrasonography, computed tomography, magnetic resonance imaging and new endoscopic approaches such as molecular endoscopy. It is expected that these novel techniques will lead to marked improvements in the assessment of disease behaviour and the prediction of response to clinical therapy with biologicals.

Death-associated protein kinase: A molecule with functional antagonistic duality and a potential role in inflammatory bowel disease (Review)

The cytoskeleton-associated serine/threonine kinase death-associated protein kinase (DAPK) has been described as a cancer gene chameleon with functional antagonistic duality in a cell type and context specific manner. The broad range of interaction partners and substrates link DAPK to inflammatory processes especially in the gut. Herein we summarize our knowledge on the role of DAPK in different cell types that play a role under inflammatory conditions in the gut. Besides some promising experimental data suggesting DAPK as an interesting drug target in inflammatory bowel disease there are many open questions regarding direct evidence for a role of DAPK in intestinal inflammation.

Confocal laser endomicroscopy to monitor the colonic mucosa of mice

The gastrointestinal tract is a unique organ system that provides an epithelial barrier between our underlying immune system and luminal pathogens. Disruption of gastrointestinal homeostasis, as a result of impaired barrier function, is associated with numerous pathologies including inflammatory bowel disease and colorectal cancer. In parallel to the clinical development of endoscopy technologies to monitor and diagnose these pathologies in humans, advanced mouse colonoscopy techniques are being developed. When these technologies are coupled with model systems of human disease, which are essential to our understanding of the pathophysiology of gastrointestinal diseases, the requirement for euthanasia of multiple cohorts of mice is eliminated. Here we highlight the suitability of white light endoscopy to monitor the progression of colitis in mice. We further outline the experimental power of combined standard endoscopy with confocal microendoscopy, which permits visualization of fluorescent markers in a single animal in real-time. Together, these technologies will enhance our understanding of the interplay between components of the gastrointestinal microenvironment and their role in disease.

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Monitoring of mucosal damage using white light endoscopy

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Monitoring of the epithelial barrier using confocal endomicroscopy

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Monitoring of the vasculature architecture using confocal endomicroscopy

Stratified medicine in inflammatory disorders: From theory to practice

Chronic inflammatory disorders are complex and characterized by significant heterogeneity in molecular, pathological, and clinical features. This heterogeneity poses challenges for the development of targeted molecular interventions for these disorders, as not all patients with a given clinical diagnosis have disease driven by a single dominant molecular pathway, hence not all patients will benefit equally from a given intervention. Biomarkers related to molecular manifestations of disease are increasingly being applied to enable stratified approaches to drug development. Biomarkers may be used to identify which patients are most likely to benefit from an intervention (predictive), identify patients at increased risk of disease progression (prognostic), and monitor biological responsiveness to an intervention (pharmacodynamic). Here we consider how biomarker-guided stratification of patients may increase benefit from targeted therapies for asthma, rheumatoid arthritis and inflammatory bowel diseases.

Pathogenesis of Crohn's disease

Significant progress in our understanding of Crohn's disease (CD), an archetypal common, complex disease, has now been achieved. Our ability to interrogate the deep complexities of the biological processes involved in maintaining gut mucosal homeostasis is a major over-riding factor underpinning this rapid progress. Key studies now offer many novel and expansive insights into the interacting roles of genetic susceptibility, immune function, and the gut microbiota in CD. Here, we provide overviews of these recent advances and new mechanistic themes, and address the challenges and prospects for translation from concept to clinic.

Electronic imaging to enhance lesion detection at colonoscopy

Adenoma removal prevents colorectal cancer (CRC) development. Lower adenoma detection rates correlate with increased postcolonoscopy CRC. Chromoendoscopy it is not practical for routine use. It was hoped that electronic imaging techniques would offer effective alternatives to improve detection; however, meta-analyses in average-risk patients indicate no benefit. Narrow band imaging may be of benefit for high-risk surveillance. Combining electronic imaging techniques with molecular imaging probes may highlight dysplasia at a molecular level. In future colonoscopy is likely to rely on sensitive and specific, labeled molecular probes detected by electronic endoscopic imaging to enhance detection and reduce miss rates for premalignant lesions.

Fluorescence-Raman dual modal endoscopic system for multiplexed molecular diagnostics

Optical endoscopic imaging, which was recently equipped with bioluminescence, fluorescence, and Raman scattering, allows minimally invasive real-time detection of pathologies on the surface of hollow organs. To characterize pathologic lesions in a multiplexed way, we developed a dual modal fluorescence-Raman endomicroscopic system (FRES), which used fluorescence and surface-enhanced Raman scattering nanoprobes (F-SERS dots). Real-time, in vivo, and multiple target detection of a specific cancer was successful, based on the fast imaging capability of fluorescence signals and the multiplex capability of simultaneously detected SERS signals using an optical fiber bundle for intraoperative endoscopic system. Human epidermal growth factor receptor 2 (HER2) and epidermal growth factor receptor (EGFR) on the breast cancer xenografts in a mouse orthotopic model were successfully detected in a multiplexed way, illustrating the potential of FRES as a molecular diagnostic instrument that enables real-time tumor characterization of receptors during routine endoscopic procedures.

Endoscopic imaging

OPINION STATEMENT

The most important tools are the eye and the brain. A detailed white-light high-resolution examination and ability to recognize subtle lesions provide the foundation of the ability to detect lesions in the gastrointestinal tract. Novel technologies are now available to provide additional information with the goals of detection, delineation, or classification often with a focus on neoplasia in the gastrointestinal tract. The observer using these new tools must still recognize, interpret, and then make a clinically relevant conclusion. Therefore, the assessment of these tools may focus on both the technical feasibility to use the respective equipment to obtain an image and then also the associated cognitive-based criteria for image interpretation.

Targeted localized use of therapeutic antibodies: a review of non-systemic, topical and oral applications

Therapeutic antibodies provide important tools in the "medicine chest" of today's clinician for the treatment of a range of disorders. Typically monoclonal or polyclonal antibodies are administered in large doses, either directly or indirectly into the circulation, via a systemic route which is well suited for disseminated ailments. Diseases confined within a specific localized tissue, however, may be treated more effectively and at reduced cost by a delivery system which targets directly the affected area. To explore the advantages of the local administration of antibodies, we reviewed current alternative, non-systemic delivery approaches which are in clinical use, being trialed or developed. These less conventional approaches comprise: (a) local injections, (b) topical and (c) peroral administration routes. Local delivery includes intra-ocular injections into the vitreal humor (i.e. Ranibizumab for age-related macular degeneration), subconjunctival injections (e.g. Bevacizumab for corneal neovascularization), intra-articular joint injections (i.e. anti-TNF alpha antibody for persistent inflammatory monoarthritis) and intratumoral or peritumoral injections (e.g. Ipilimumab for cancer). A range of other strategies, such as the local use of antibacterial antibodies, are also presented. Local injections of antibodies utilize doses which range from 1/10th to 1/100th of the required systemic dose therefore reducing both side-effects and treatment costs. In addition, any therapeutic antibody escaping from the local site of disease into the systemic circulation is immediately diluted within the large blood volume, further lowering the potential for unwanted effects. Needle-free topical application routes become an option when the condition is restricted locally to an external surface. The topical route may potentially be utilized in the form of eye drops for infections or corneal neovascularization or be applied to diseased skin for psoriasis, dermatitis, pyoderma gangrenosum, antibiotic resistant bacterial infections or ulcerated wounds. Diseases confined to the gastrointestinal tract can be targeted directly by applying antibody via the injection-free peroral route. The gastrointestinal tract is unusual in that its natural immuno-tolerant nature ensures the long-term safety of repeatedly ingesting heterologous antiserum or antibody materials. Without the stringent regulatory, purity and clean room requirements of manufacturing parenteral (injectable) antibodies, production costs are minimal, with the potential for more direct low-cost targeting of gastrointestinal diseases, especially with those caused by problematic antibiotic resistant or toxigenic bacteria (e.g. Clostridium difficile, Helicobacter pylori), viruses (e.g. rotavirus, norovirus) or inflammatory bowel disease (e.g. ulcerative colitis, Crohn's disease). Use of the oral route has previously been hindered by excessive antibody digestion within the gastrointestinal tract; however, this limitation may be overcome by intelligently applying one or more strategies (i.e. decoy proteins, masking therapeutic antibody cleavage sites, pH modulation, enzyme inhibition or encapsulation). These aspects are additionally discussed in this review and novel insights also provided. With the development of new applications via local injections, topical and peroral routes, it is envisaged that an extended range of ailments will increasingly fall within the clinical scope of therapeutic antibodies further expanding this market.

Differential diagnosis in inflammatory bowel disease colitis: State of the art and future perspectives

Distinction between Crohn’s disease of the colon-rectum and ulcerative colitis or inflammatory bowel disease (IBD) type unclassified can be of pivotal importance for a tailored clinical management, as each entity often involves specific therapeutic strategies and prognosis. Nonetheless, no gold standard is available and the uncertainty of diagnosis may frequently lead to misclassification or repeated examinations. Hence, we have performed a literature search to address the problem of differential diagnosis in IBD colitis, revised current and emerging diagnostic tools and refined disease classification strategies. Nowadays, the differential diagnosis is an untangled issue, and the proper diagnosis cannot be reached in up to 10% of patients presenting with IBD colitis. This topic is receiving emerging attention, as medical therapies, surgical approaches and leading prognostic outcomes require more and more disease-specific strategies in IBD patients. The optimization of standard diagnostic approaches based on clinical features, biomarkers, radiology, endoscopy and histopathology appears to provide only marginal benefits. Conversely, emerging diagnostic techniques in the field of gastrointestinal endoscopy, molecular pathology, genetics, epigenetics, metabolomics and proteomics have already shown promising results. Novel advanced endoscopic imaging techniques and biomarkers can shed new light for the differential diagnosis of IBD, better reflecting diverse disease behaviors based on specific pathogenic pathways.

The current and future role of endomicroscopy in the management of inflammatory bowel disease

Confocal laser-induced endomicroscopy (CLE), first introduced in 2003, allows the capture of images of "virtual histology" of the gastrointestinal mucosa during endoscopy, providing the opportunity to retrieve real-time visualization of the pathology of the mucosal epithelium with its cellular and subcellular structures. This new endoscopic imaging technique serves as an adjunctive diagnostic tool to the traditional ileocolonoscopy in the management of inflammatory bowel disease (IBD) patients. In multiple clinical trials, CLE has been shown to improve detection of dysplasia, assess disease activity, predict future clinical relapses, and assess potential responsiveness to anti-tumor necrosis factor therapy. This review explores in depth the current and future role of CLE in the management of IBD patients.

Novel imaging modalities for immune cell monitoring in the intestine

PURPOSE OF REVIEW

The introduction of novel molecular imaging modalities that can not only define disease states on the basis of structural changes and morphology, but also allow in-vivo visualization and characterization of molecular and biochemical alterations on a cellular level add a new dimension to our current diagnostic possibilities. The advents of innovative endoscopic devices coupled with the introduction of novel targeting ligands contribute to the recent advances made in the field of molecular imaging. The purpose of this review is to present and discuss the concepts and the potential of novel endoscopic imaging modalities for immune cell monitoring in the intestine.

RECENT FINDINGS

Recent progress concerning molecular imaging studies in animals and human patients implicates that this approach can be used to improve detection of mucosal lesions in wide-field imaging and for in-vivo characterization of the mucosa with the ultimate goal of assessing the likelihood of response to targeted therapy with biological agents. In particular, molecular endomicroscopy for assessment of mucosal immune responses ('immunoendoscopy') emerges as a novel approach for optimized endoscopic diagnosis and individualized therapy.

SUMMARY

Molecular imaging modalities in the intestine have the immediate potential to have an impact on current clinical practice and could therefore open new frontiers for clinical endoscopy and give hope for improved diagnosis and targeted therapies.

Role of programmed necrosis and cell death in intestinal inflammation

PURPOSE OF REVIEW

To critically review recent advances on the role of programmed necrosis and other cell death modalities in intestinal health and inflammatory bowel disease.

RECENT FINDINGS

Tight regulation of intestinal epithelial cell proliferation and cell death is required for intestinal physiology, and to maintain an integral barrier that restricts microbiota translocation and ensures immune tolerance. Apoptosis has long been considered as a normal part of intestinal epithelial cell turnover. However, recent studies have demonstrated that excessive cell death leads to deleterious intestinal inflammation, as is observed in inflammatory bowel disease. Additionally, a novel form of cell death dubbed programmed necrosis, or necroptosis, has been recently shown to be pathological in the gut.

SUMMARY

The role of cell death in the intestine is complex and its potential implication in intestinal diseases, and inflammatory bowel disease in particular, needs to be reevaluated.

Cytokines and mucosal immunity

PURPOSE OF REVIEW

Cytokines are integral mediators for maintaining intestinal mucosal homeostasis, as well as prominent effector molecules during chronic gut inflammatory diseases. This review focuses on recent studies of the role of specific cytokines in mucosal immunity.

RECENT FINDINGS

Dichotomous, or even opposing, functions have been described for several cytokines involved in intestinal innate immunity (most notably for members of the interleukin-1 family), which depend on the specific inflammatory conditions within the intestinal mucosa. For example, both interleukin-1α and interleukin-33 exhibit 'alarmin'-type properties that can signal tissue or cell damage, which further add to their well described proinflammatory roles. Costimulatory molecules of the tumor necrosis factor/tumor necrosis factor receptor superfamily, such as TNF-like cytokine 1A and LIGHT, are actively involved in mucosal proinflammatory pathways, but also may exert protection against infectious agents to facilitate recovery from acute inflammation. Finally, innate lymphoid cells are increasingly recognized as important cellular sources of pivotal mucosal cytokines, including the interleukin-23/T helper 17 cytokine, interleukin-22.

SUMMARY

Elucidating the complexity of cytokine signaling within the normal mucosa and during acute and chronic inflammation will be a pivotal step toward understanding the pathogenesis of immune-mediated gut diseases and developing effective therapies to treat them.

Colitis-associated neoplasia: molecular basis and clinical translation

Crohn's disease and ulcerative colitis are both associated with an increased risk of inflammation-associated colorectal carcinoma. Colitis-associated cancer (CAC) is one of the most important causes for morbidity and mortality in patients with inflammatory bowel diseases (IBD). Colitis-associated neoplasia distinctly differs from sporadic colorectal cancer in its biology and the underlying mechanisms. This review discusses the molecular mechanisms of CAC and summarizes the most important genetic alterations and signaling pathways involved in inflammatory carcinogenesis. Then, clinical translation is evaluated by discussing new endoscopic techniques and their contribution to surveillance and early detection of CAC. Last, we briefly address different types of concepts for prevention (i.e., anti-inflammatory therapeutics) and treatment (i.e., surgical intervention) of CAC and give an outlook on this important aspect of IBD.

Molecular imaging of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a kind of chronic non-specific intestinal inflammatory disease of unknown etiology. Traditional imaging is difficult for early detection of mucosal lesions and is not conducive to early treatment. Colonoscopy is a kind of invasive procedure, and its clinical use is therefore limited. Molecular imaging provides a new approach for early diagnosis of IBD. In this paper, we review recent advances in molecular imaging of IBD.

TNF and TNF-receptors: From mediators of cell death and inflammation to therapeutic giants - past, present and future

Tumor Necrosis Factor (TNF), initially known for its tumor cytotoxicity, is a potent mediator of inflammation, as well as many normal physiological functions in homeostasis and health, and anti-microbial immunity. It also appears to have a central role in neurobiology, although this area of TNF biology is only recently emerging. Here, we review the basic biology of TNF and its normal effector functions, and discuss the advantages and disadvantages of therapeutic neutralization of TNF - now a commonplace practice in the treatment of a wide range of human inflammatory diseases. With over ten years of experience, and an emerging range of anti-TNF biologics now available, we also review their modes of action, which appear to be far more complex than had originally been anticipated. Finally, we highlight the current challenges for therapeutic intervention of TNF: (i) to discover and produce orally delivered small molecule TNF-inhibitors, (ii) to specifically target selected TNF producing cells or individual (diseased) tissue targets, and (iii) to pre-identify anti-TNF treatment responders. Although the future looks bright, the therapeutic modulation of TNF now moves into the era of personalized medicine with society's challenging expectations of durable treatment success and of achieving long-term disease remission.

Beyond standard image-enhanced endoscopy confocal endomicroscopy

Endomicroscopy is a new imaging tool for gastrointestinal endoscopy. In vivo histology becomes possible at subcellular resolution during ongoing colonoscopy. Panchromoendoscopy with targeted biopsies has become the method of choice for surveillance of patients with inflammatory bowel disease. Endomicroscopy can be added after chromoendoscopy to clarify whether standard biopsies are needed. This smart biopsy concept can increase the diagnostic yield of intraepithelial neoplasia and substantially reduce the need for biopsies. Clinical acceptance is increasing because of a multitude of positive studies about the diagnostic value of endomicroscopy. Smart biopsies, functional imaging, and molecular imaging may represent the future for endomicroscopy.

Not all monoclonals are created equal - lessons from failed drug trials in Crohn's disease

The recent success of the anti-integrin antibody Vedolizumab can barely conceal the fact that the biologics armamentarium in Crohn's disease has barely evolved beyond TNF blockers so far. This contrasts with other immune-related diseases considered mechanistically and genetically closely related, such as psoriasis and rheumatoid arthritis, where approved biologics target a variety of independent biological mechanisms. Several pharmacological assets that entered clinical development have proven ineffective, or less effective than originally anticipated. While blockade of IL-17A and its receptor via Secukinumab and Brodalumab, respectively, worsened Crohn's disease, the beneficial effect of IL-12/23 p40 blockade via Ustekinumab appeared confined to a subpopulation of Crohn's disease patients who have previously failed on TNF blockers. Clinical development of the IFNγ blocker Fontolizumab was stopped despite demonstrating some clinical benefit, while the T cell co-stimulation blocker Abatacept did not exhibit any hint towards efficacy in Crohn's disease. Here I review results from these individual development programmes, and also reflect on the lack of efficacy of the TNF blocker Etanercept. I will discuss aspects of individual trials that might have confounded their interpretation and highlight the evolution in primary and secondary endpoints that have contributed to increasing robustness of results obtained in recent years. Finally, I suggest that mechanistic studies in murine genetic models combined with exploratory immunological studies incorporated in early drug development may represent the key for identifying the next generation of successful pharmacological targets in Crohn's disease.

Cytokines in inflammatory bowel disease

Cytokines have a crucial role in the pathogenesis of inflammatory bowel diseases (IBDs), such as Crohn's disease and ulcerative colitis, where they control multiple aspects of the inflammatory response. In particular, the imbalance between pro-inflammatory and anti-inflammatory cytokines that occurs in IBD impedes the resolution of inflammation and instead leads to disease perpetuation and tissue destruction. Recent studies suggest the existence of a network of regulatory cytokines that has important implications for disease progression. In this Review, we discuss the role of cytokines produced by innate and adaptive immune cells, as well as their relevance to the future therapy of IBD.