Endomicroscopy and endocytoscopy in IBD

Alterations in Intestinal Mucosal Barrier Visualized by Confocal Laser Endomicroscopy in Liver Cirrhosis: A Pilot Trial (AMBIC)

BACKGROUND

Chronic liver disease occurs throughout the world irrespective of region, age, sex, or race, and it is caused by a variety of liver conditions. One of the most frequent infectious complications in liver cirrhosis that severely reduces the median survival is spontaneous bacterial peritonitis. Current guidelines recommend a paracentesis before starting an antibiotic prophylaxis for this complication.

METHODS

Selective intestinal decontamination significantly lowers the rate of first or recurrent SBP in cirrhotic patients, so in this study we aimed to investigate and quantify the intestinal integrity of patients with liver cirrhosis and correlate a pathologically increased permeability with the incidence of SPB. We included 14 patients who met the inclusion criteria. No patient was excluded. For the CLE investigation, we use probe based confocal laser endomicroscopy techniques from Mauna Kea (Cellvizio), enabling in vivo surface imaging. The images (optical biopsies) were analyzed for functional and structural barrier defects after the procedure using Mauna Kea software (version 1.0.09).

RESULTS

Because of the small number of included patients and healthy controls, most results are lacking statistical relevance. We found that the CLE investigation showed an increased intestinal permeability in patients with liver cirrhosis, in concordance with previous published data, based on other assessment methods.

CONCLUSIONS

This study confirms that previously published permeability scores can be applied for patients with liver cirrhosis and is, to our knowledge, the first to investigate the intestinal permeability in vivo in patients with liver cirrhosis. Further data are needed to identify patients at risk and help develop new and less invasive diagnostic criteria for cirrhotic patients who may profit from a prophylactic antibiotic treatment.

Visualising and quantifying intestinal permeability -where do we stand

Intestinal permeability is getting more and more attention in gastrointestinal research. Although well recognized, its exact role in health and disease is yet to be defined. There are many methods of quantifying intestinal permeability, but most of them fail to deliver tangible information about the morphological integrity of the intestinal barrier. In this review we aim to describe imaging options for the assessment of intestinal barrier integrity and their potential relevance for clinical practice. Our focus is on confocal laser endomicroscopy, which is at this time the only method for visualizing not only functional but also morphological aspects of the gut barrier in vivo.

The Esophageal Epithelial Barrier in Health and Disease

Dysfunction in the esophageal epithelial barrier function is a major source for morbidity. To better understand the pathophysiologic pathways of the diseases associated with barrier dysfunction, including gastroesophageal reflux disease, eosinophilic esophagitis, Barrett's esophagus, and obesity, it is important to understand the esophageal epithelial embryologic development, microscopic anatomy with a special focus on the barrier structure and function, extraepithelial defense mechanisms, and how these change in the diseased state. In recent years, significant progress has been made in elucidating the esophageal barrier structure and function both in vitro and in vivo. This has enhanced the understanding of mechanisms of disease, and may also allow identification of therapeutic targets that can help in the management of these diseases. This review provides a detailed discussion regarding the esophageal epithelial barrier structure and function, the current and historical techniques used to study the barrier, and how it is affected by common esophageal diseases.

An Update on Surveillance in Ulcerative Colitis

PURPOSE OF REVIEW

Patients with long-standing ulcerative colitis have an increased risk for the development of colorectal cancer (CRC). Colitis-related dysplasia appears to confer the greatest risk. Colonoscopic surveillance to detect dysplasia has been advocated by gastrointestinal societies. The aim of surveillance is the reduction of mortality and morbidity of CRC through detection and resection of dysplasia or detecting CRC at an earlier and potentially curable stage. Traditional surveillance has relied on mucosal assessment with targeted biopsy of visible lesions and random biopsy sampling on the premise that dysplasia was not visible at endoscopy. Advances in optical technology permitting increased detection of dysplasia and evidence that most dysplasia is visible has had practice-changing implications.

RECENT FINDINGS

Emerging evidence favours chromoendoscopy (CE) for dysplasia detection and is gaining wider acceptance through recent international (International Consensus Statement on Surveillance and Management of Dysplasia in Inflammatory Bowel Disease (SCENIC)) recommendations and endorsed by many gastrointestinal societies. Adoption of CE as the gold standard of surveillance has been met with by scepticism, from conflicting data, operational barriers and the need to understand the true impact of increasingly higher dysplasia detection on overall CRC mortality. Valid debate notwithstanding, implementation of a risk stratification protocol that includes CE is an effective approach allowing earlier detection of dysplasia and colorectal neoplasia, determination of surveillance intervals with appropriate allocation of resources and limiting morbidity from CRC and colonoscopy itself. Further prospective data should define the true and long-term impact of dysplasia detection with modern techniques.

ZnO nanoparticles act as supportive therapy in DSS-induced ulcerative colitis in mice by maintaining gut homeostasis and activating Nrf2 signaling

Inflammatory bowel diseases (IBD) are widespread inflammatory diseases that cause debilitating health problems including cancer. In this study, we show that ZnO nanoparticle (ZnONP) treatment has markedly dose-dependent effects on the remission of dextran sulfate sodium (DSS)-induced ulcerative colitis in mice. We demonstrate the mechanism involves the antioxidant and anti-inflammatory abilities of ZnONPs to suppress ROS and malondialdehyde (MDA) production; increase GSH level; suppress proinflammatory cytokines IL-1β and TNF-α and myeloperoxidase (MPO). The ZnONP treatment is able to activate the Nrf2 pathway in the cellular antioxidant defense system. The novel finding is that ZnONP combined with mesalazine (5-ASA) can enhance the therapeutic efficacy of 5-ASA in the treatment of DSS-induced colitis. Lastly, we found that ZnONP treatment can restore the changes in special colonic bacteria of DSS-mice while the drug 5-ASA cannot. These results indicate that ZnONPs can act as a medical additive for the therapy of IBD.

How to Optimize Colon Cancer Surveillance in Inflammatory Bowel Disease Patients

Colitis-associated colorectal neoplasia (CRN) is a well-known complication of chronic inflammation of the colon either with ulcerative colitis (UC) or colonic Crohn's disease (CD). Studies have shown that inflammatory bowel disease (IBD) patients have an overall higher risk for colorectal dysplasia and cancer compared to the general population and this risk is further increased by certain associated factors, including extent of disease, duration of disease, and age at onset. In addition, other risk factors not related to IBD can also further increase the risk for CRN, such as a family history of sporadic colon cancer and a concomitant diagnosis of primary sclerosing cholangitis. The society guidelines mostly agree on the appropriate time to begin CRN surveillance but vary somewhat on the appropriate intervals between surveillance colonoscopies. In addition, there is not yet a consensus on the appropriate method for surveillance. In this review, we discuss the risk for CRN in colonic IBD, the associated factors that further increase the risk for CRN, the current surveillance guidelines and the current methods available for CRN surveillance.

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.

Diagnostic performance of endocytoscopy for evaluating the invasion depth of different morphological types of colorectal tumors

BACKGROUND AND AIM

Endocytoscopy (EC) is a next-generation endoscopic technique that enables diagnostic imaging at 450× magnification. In the present study, we retrospectively evaluated the diagnostic performance of EC and magnifying chromoendoscopy (MCE) for diagnosing the invasion depth of colorectal tumors.

METHODS

We investigated 330 lesions with a ≥10-mm tumor diameter that could be diagnosed by both MCE and EC. The lesions were classified according to morphological type as follows: laterally spreading type-granular (LST-G), laterally spreading type-non-granular (LST-NG), protruding, or depressed. After all lesions had been classified by both pit pattern and EC, qualitative and quantitative (invasion depth) diagnoses were made. The diagnostic accuracy was then compared between pit pattern classification and EC classification.

RESULTS

Diagnostic accuracy of EC classification was significantly higher for LST-NG lesions (90.5%) than for protruding lesions (80.6%) (P < 0.05). Diagnostic accuracy for LST-NG lesions was significantly higher with EC classification (90.5%) than with pit pattern classification (79.3%) (P < 0.001). Comparison of the diagnostic performance of EC3a findings using EC classification between LST-NG and protruding lesions revealed a sensitivity of 92.9% versus 11.3% (P < 0.001), positive predictive value of 78.0% versus 27.3% (P < 0.001), negative predictive value of 95.5% versus 56.1% (P < 0.001), and diagnostic accuracy of 87.9% versus 51.2% (P < 0.001), respectively.

CONCLUSION

EC is a very useful method for evaluating the invasion depth of LST-NG lesions.

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.

Application of confocal laser endomicroscopy in ulcerative colitis

The etiology of ulcerative colitis (UC) is not very clear. Most scholars believe that intestinal inflammation caused by immune system abnormalities plays an important role in the pathogenesis of UC. The clinical course of UC is characterized by episodes of exacerbation and remission alternately. Traditional electronic endoscopy with random biopsy plays an important role in the diagnosis, treatment and prognosis evaluation of UC. However, this method has some deficiencies, such as poor sensitivity, cumbersome procedures, bleeding caused by multiple biopsies and other complications. The advent of high resolution confocal laser endomicroscopy (CLE) can allow real-time, noninvasive histopathological examination in vivo, to achieve the goal of "virtual biopsy". This paper reviews the application of CLE in UC.

Detection of a fluorescent-labeled avidin-nucleic acid nanoassembly by confocal laser endomicroscopy in the microvasculature of chronically inflamed intestinal mucosa

Inflammatory bowel diseases are chronic gastrointestinal pathologies causing great discomfort in both children and adults. The pathogenesis of inflammatory bowel diseases is not yet fully understood and their diagnosis and treatment are often challenging. Nanoparticle-based strategies have been tested in local drug delivery to the inflamed colon. Here, we have investigated the use of the novel avidin-nucleic acid nanoassembly (ANANAS) platform as a potential diagnostic carrier in an experimental model of inflammatory bowel diseases. Fluorescent- labeled ANANAS nanoparticles were administered to mice with chemically induced chronic inflammation of the large intestine. Localization of mucosal nanoparticles was assessed in vivo by dual-band confocal laser endomicroscopy. This technique enables characterization of the mucosal microvasculature and crypt architecture at subcellular resolution. Intravascular nanoparticle distribution was observed in the inflamed mucosa but not in healthy controls, demonstrating the utility of the combination of ANANAS and confocal laser endomicroscopy for highlighting intestinal inflammatory conditions. The specific localization of ANANAS in inflamed tissues supports the potential of this platform as a targeted carrier for bioactive moieties in the treatment of inflammatory bowel disease.

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.

Advanced colonoscopic imaging using endocytoscopy

Optical biopsy techniques were recently introduced to luminal gastrointestinal endoscopy. These include confocal laser endomicroscopy, spectroscopic imaging techniques and endocytoscopy. Optical biopsy techniques allow on demand in vivo histology during ongoing endoscopy, thereby potentially accelerating clinical diagnosis and specific therapy. In the present review, we focus on endocytoscopy as one of the rapidly emerging optical biopsy techniques. We provide technical details of currently available endocytoscopy systems and give tips on their use in clinical practice. We also summarize applications of endocytoscopy for colorectal pathologies.

Endoscopic scoring systems for inflammatory bowel disease: pros and cons

Endoscopy plays a pivotal role for diagnosis and assessment of disease activity and extent in patients with inflammatory bowel diseases. International guidelines recommend the use of endoscopic scoring systems for evaluation of the prognosis and efficacy of medical treatments. Ideal scoring systems are easy to use, reproducible, reliable, responsive to changes, and validated in different clinical settings in order to guide therapeutic strategies. However, currently available endoscopic scoring systems often appear as complex for routine endoscopy and suffer from insufficient interobserver agreement and lack of formal validation which often limit their use in clinical trials. Here, we describe the role of endoscopic scoring systems in inflammatory bowel diseases focusing on pros and cons in the era of advanced endoscopic imaging and mucosal healing.

Advanced endoscopic imaging techniques in Crohn's disease

BACKGROUND

Endoscopy is of pivotal importance in Crohn's disease (CD) patients for diagnosis, surveillance and assessment of disease activity and extent. Device-assisted enteroscopy (DAE) and small-bowel capsule endoscopy (SBCE) have recently changed our endoscopic approach to small-bowel imaging. Furthermore, new advanced endoscopic imaging techniques have been implemented into clinical practice to improve both characterization of mucosal inflammation and detection of dysplastic lesions.

AIM

To provide readers with a review about the concept of advanced endoscopic imaging for the diagnosis and characterization of CD.

METHODS

A literature search on the use of advanced endoscopy techniques in IBD patients was performed.

RESULTS

DAE and SBCE allow for deep enteroscopy with high diagnostic yields and low complication's rate but their collocation in the diagnostic algorithm is still not clearly defined. Dye-based chromoendoscopy (DBC) and magnification chromoendoscopy improved dysplasia's detection in long standing colitis and prediction of inflammatory activity and extent. Dye-less chromoendoscopy (DLC) might offer the potential to replace conventional DBC for surveillance. However, both narrow band imaging and i-scan have already shown to significantly improve activity and extent assessment in comparison to white-light endoscopy. Confocal laser endomicroscopy (CLE) can detect more dysplastic lesions in surveillance colonoscopy and predict neoplastic and inflammatory changes with high accuracy compared to histology. Moreover, CLE-based molecular imaging may anticipate the therapeutic responses to biological therapy. Endocytoscopy can identify in vivo inflammatory mucosal cells harboring a new method to assess the mucosal activity.

CONCLUSIONS

Recent progresses in small-bowel enteroscopy offer several potential benefits to improve both diagnosis and characterization of CD. New advanced endoscopic imaging techniques can improve detection of dysplasia and refine mucosal healing assessment, even looking beyond the morphological parameters revealed by conventional endoscopic imaging.

Confocal laser endomicroscopy for prediction of disease relapse in ulcerative colitis: a pilot study

BACKGROUND AND AIMS

Neoangiogenesis and increased endothelial permeability are observed as results of chronic intestinal inflammation. However, limited data on microvascular and crypt architecture during remission phases is available. The aim of this prospective investigator blinded cohort study was to assess crypt and microvascular architecture and function in ulcerative colitis by probe based confocal laser endomicroscopy; we also evaluated whether these findings may have the potential to predict disease relapse.

METHODS

19 ulcerative colitis patients in clinical and endoscopic remission and 19 controls were studied. A computer based image processing technique was applied to construct 20 mosaicing image sets from each subject. Remitting patients were sub-grouped into either inactive or quiescent disease according to histology.

RESULTS

Pericrypt fluorescence (p<0.01), crypt diameter (p<0.05) but not intercrypt distance (p=0.07) were significantly increased in ulcerative colitis patients compared to controls. Patients with inactive disease showed a significant increase in fluorescence leakage (median fluorescence (IQR), 3888 (3560-4240) vs. 2696 (2502-3390), p<0.01), crypt diameter (median diameter (IQR), 92.5 (85.5-101) vs. 73 (70-77), p<0.05) and intercrypt distance (median distance (IQR), 82.5 (70.5-91.2) vs. 66 (59.5-73.5), p<0.05) compared to those with quiescent disease. A composite outcome score combining fluorescence leakage and crypt diameter was able to predict a disease flare during a 12 month follow-up period (p<0.01).

CONCLUSIONS

In vivo intramucosal changes detected by confocal endomicroscopy in ulcerative colitis remittent patients can predict disease relapse. This observation may have further implications for disease management and medical treatment.

Optical molecular imaging for diagnosing intestinal diseases

Real-time visualization of the molecular signature of cells can be achieved with advanced targeted imaging techniques using molecular probes and fluorescence endoscopy. This molecular optical imaging in gastrointestinal endoscopy is promising for improving the detection of neoplastic lesions, their characterization for patient stratification, and the assessment of their response to molecular targeted therapy and radiotherapy. In inflammatory bowel disease, this method can be used to detect dysplasia in the presence of background inflammation and to visualize inflammatory molecular targets for assessing disease severity and prognosis. Several preclinical and clinical trials have applied this method in endoscopy; however, this field has just started to evolve. Hence, many problems have yet to be solved to enable the clinical application of this novel method.