Assessment of Histological Remission in Ulcerative Colitis: Discrepancies Between Daily Practice and Expert Opinion

Artificial intelligence: A new tool in the pathologist's armamentarium for the diagnosis of IBD

Inflammatory bowel diseases (IBD) are classified into two entities, namely Crohn's disease (CD) and ulcerative colitis (UC), which differ in disease trajectories, genetics, epidemiological, clinical, endoscopic, and histopathological aspects. As no single golden standard modality for diagnosing IBD exists, the differential diagnosis among UC, CD, and non-IBD involves a multidisciplinary approach, considering professional groups that include gastroenterologists, endoscopists, radiologists, and pathologists. In this context, histological examination of endoscopic or surgical specimens plays a fundamental role. Nevertheless, in differentiating IBD from non-IBD colitis, the histopathological evaluation of the morphological lesions is limited by sampling and subjective human judgment, leading to potential diagnostic discrepancies. To overcome these limitations, artificial intelligence (AI) techniques are emerging to enable automated analysis of medical images with advantages in accuracy, precision, and speed of investigation, increasing interest in the histological analysis of gastrointestinal inflammation. This review aims to provide an overview of the most recent knowledge and advances in AI methods, summarizing its applications in the histopathological analysis of endoscopic biopsies from IBD patients, and discussing its strengths and limitations in daily clinical practice.

Artificial intelligence and endo-histo-omics: new dimensions of precision endoscopy and histology in inflammatory bowel disease

Integrating artificial intelligence into inflammatory bowel disease (IBD) has the potential to revolutionise clinical practice and research. Artificial intelligence harnesses advanced algorithms to deliver accurate assessments of IBD endoscopy and histology, offering precise evaluations of disease activity, standardised scoring, and outcome prediction. Furthermore, artificial intelligence offers the potential for a holistic endo-histo-omics approach by interlacing and harmonising endoscopy, histology, and omics data towards precision medicine. The emerging applications of artificial intelligence could pave the way for personalised medicine in IBD, offering patient stratification for the most beneficial therapy with minimal risk. Although artificial intelligence holds promise, challenges remain, including data quality, standardisation, reproducibility, scarcity of randomised controlled trials, clinical implementation, ethical concerns, legal liability, and regulatory issues. The development of standardised guidelines and interdisciplinary collaboration, including policy makers and regulatory agencies, is crucial for addressing these challenges and advancing artificial intelligence in IBD clinical practice and trials.

Advancements in computer vision and pathology: Unraveling the potential of artificial intelligence for precision diagnosis and beyond

The integration of computer vision into pathology through slide digitalization represents a transformative leap in the field's evolution. Traditional pathology methods, while reliable, are often time-consuming and susceptible to intra- and interobserver variability. In contrast, computer vision, empowered by artificial intelligence (AI) and machine learning (ML), promises revolutionary changes, offering consistent, reproducible, and objective results with ever-increasing speed and scalability. The applications of advanced algorithms and deep learning architectures like CNNs and U-Nets augment pathologists' diagnostic capabilities, opening new frontiers in automated image analysis. As these technologies mature and integrate into digital pathology workflows, they are poised to provide deeper insights into disease processes, quantify and standardize biomarkers, enhance patient outcomes, and automate routine tasks, reducing pathologists' workload. However, this transformative force calls for cross-disciplinary collaboration between pathologists, computer scientists, and industry innovators to drive research and development. While acknowledging its potential, this chapter addresses the limitations of AI in pathology, encompassing technical, practical, and ethical considerations during development and implementation.

The Evolving Role of Artificial Intelligence in Gastrointestinal Histopathology: An Update

Significant advances in artificial intelligence (AI) over the past decade potentially may lead to dramatic effects on clinical practice. Digitized histology represents an area ripe for AI implementation. We describe several current needs within the world of gastrointestinal histopathology, and outline, using currently studied models, how AI potentially can address them. We also highlight pitfalls as AI makes inroads into clinical practice.

Ulcerative colitis: STRIDE-ing beyond symptoms with new standards

The landscape of ulcerative colitis has changed in the last two decades. Advancements in pharmacotherapeutics have heralded the introduction of new treatment options, with many agents in development. Better clinical outcomes are seen with tighter disease control, made possible with greater understanding of inflammatory pathways and their blockade with drugs. There has been a resultant shift in treatment targets, beyond symptoms to endoscopic and histological healing. Controlling the burden of disease activity also lowers the risk of developing colorectal cancer. Colorectal cancer screening now requires the use of dye-based agents and high-definition colonoscopy to improve the detection of colonic neoplasms.

Considering Histologic Remission in Ulcerative Colitis as a Long-Term Target

Monitoring disease activity in inflammatory bowel disease (IBD) is challenging since clinical manifestations do not represent reliable surrogates for an accurate reflection of the inflammatory burden. Endoscopic remission had been the most significant endpoint target in the last years; nevertheless, a remarkable proportion of patients continue to relapse despite a normal-appearing mucosa, highlighting that endoscopy may underestimate the true extent of the disease. A subtle hint of the importance that histology plays in the long-term course of the disease has been endorsed by the STRIDE-II consensus, which recommends considering histologic healing for ulcerative colitis (UC), even though it is not stated to be a compulsory formal target. It is a continuum-changing paradigm, and it is almost a certainty that in the near future, histologic healing may become the new formal target for ulcerative colitis. It must be emphasized that there is great heterogeneity in defining histological remission, and the main criteria or cut-off values for inflammatory markers are still in an ill-defined area. The complexity of some histologic scores is a source of confusion among clinicians and pathologists, leading to low adherence in clinical practice when it comes to a homogenous histopathological report. Therefore, a standardized and more practical approach is urgently needed.

Histologic assessments in ulcerative colitis: the evidence behind a new endpoint in clinical trials

INTRODUCTION

Treatment goals for ulcerative colitis (UC) are evolving from the achievement of clinical remission to more rigorous goals defined by endoscopic and histologic healing. Achievement of deeper remission targets aims to reduce the risk of colectomy, hospitalizations, and colorectal cancer.

AREAS COVERED

This review covers histologic assessments, histologic remission as a clinical trial endpoint, and the association between histologic disease activity and clinical outcomes. Future directions are also discussed, including the use of advanced imaging and artificial intelligence technologies, as well as potential future treatment targets beyond histologic remission.

EXPERT OPINION

Histologic assessments are used for their sensitivity in measuring mucosal inflammatory changes in UC. Due to correlation with disease activity, histologic assessments may support clinical decision-making regarding treatment decisions as such assessments can be associated with rates of clinical relapse, hospitalization, colectomy, and neoplasia. While histologic remission is limited by varying definitions and multiple histologic indices, work is ongoing to create a consensus on the use of histologic assessments in clinical trials. As research advances, aspirational targets beyond histologic remission, such as molecular healing and disease clearance, are being explored.

Neutrophil-only Histological Assessment of Ulcerative Colitis Correlates with Endoscopic Activity and Predicts Long-term Outcomes in a Multicentre Study

BACKGROUNDS AND AIMS

Absence of neutrophils is the minimum standard to consider histological remission of ulcerative colitis [UC]. The PICaSSO Histological Remission Index [PHRI] is a new simple index for UC, based only on the detection of neutrophils. We evaluate PHRI's correlation with endoscopy and its prognostic value compared with other established indices.

METHODS

Consecutive patients with UC underwent colonoscopy at two referral centres [Birmingham, UK, and Milan, Italy,] and were followed up for 2 years. Correlation between histology (PHRI, Nancy [NHI], and Robarts [RHI] indexes) and endoscopy (Mayo Endoscopic Score [MES], Ulcerative Colitis Endoscopic Index of Severity [UCEIS], and PICaSSO index) was calculated as Spearman coefficients. Diagnostic performance of endoscopy was assessed with receiver operating characteristic [ROC] curves and outcome stratification with Kaplan-Meier curves.

RESULTS

A total of 192 patients with UC was enrolled, representing all grades of endoscopic severity. Correlation between histology and endoscopy did not differ significantly when using PHRI instead of NHI or RHI. In particular, PHRI's correlation with MES, UCEIS, and PICaSSO was 0.745, 0.718, and 0.694, respectively. Endoscopically-assessed remission reflected the absence of neutrophils [PHRI = 0] with areas under the ROC curve of 0.905, 0.906, and 0.877 for MES, UCEIS, and PICaSSO, respectively. The hazard ratio for disease flare between patients in histological activity/remission was statistically similar [p >0.05] across indexes [2.752, 2.706, and 2.871 for RHI, NHI, and PHRI, respectively].

CONCLUSION

PHRI correlates with endoscopy and stratifies risk of relapse similarly to RHI and NHI. Neutrophil-only assessment of UC is a simple yet viable alternative to established histological scores.

Inflammatory Bowel Diseases: Does One Histological Score Fit All?

Mucosal healing (MH) is the main treatment target in ulcerative colitis (UC) and Crohn's disease, and it is defined by the combination of complete endoscopic and histologic remission. The complete resolution of mucosal inflammation should be confirmed by histology but its assessment is not always univocal. Neutrophil infiltration represents the unique histological marker in discriminating the active vs. quiescent phases of the disease, together with crypt injuries (cryptitis and crypt abscesses), erosions, and ulcerations. On the contrary, basal plasmacytosis is not indicative of activity or the remission of inflammatory bowel diseases (IBDs) but instead represents a diagnostic clue, mostly at the onset. Several histological scoring systems have been developed to assess grade severity, particularly for UC. However, most are complex and/or subjective. The aim of this review was to summarize available scores, their characteristics and limitations, and to present the advantages of a simplified mucosa healing scheme (SHMHS) based on neutrophils and their distribution in the gut mucosa. Finally, we overview future developments including artificial intelligence models for standardization of disease assessments and novel molecular markers of inflammation with potential application in diagnostic practice.

Artificial Intelligence Enables Quantitative Assessment of Ulcerative Colitis Histology

Ulcerative colitis is a chronic inflammatory bowel disease that is characterized by a relapsing and remitting course. Assessment of disease activity critically informs treatment decisions. In addition to endoscopic remission, histologic remission is emerging as a treatment target and a key factor in the evaluation of disease activity and therapeutic efficacy. However, manual pathologist evaluation is semiquantitative and limited in granularity. Machine learning approaches are increasingly being developed to aid pathologists in accurate and reproducible scoring of histology, enabling precise quantitation of clinically relevant features. Here, we report the development and validation of convolutional neural network models that quantify histologic features pertinent to ulcerative colitis disease activity, directly from hematoxylin and eosin-stained whole slide images. Tissue and cell model predictions were used to generate quantitative human-interpretable features to fully characterize the histology samples. Tissue and cell predictions showed comparable agreement to pathologist annotations, and the extracted slide-level human-interpretable features demonstrated strong correlations with disease severity and pathologist-assigned Nancy histological index scores. Moreover, using a random forest classifier based on 13 human-interpretable features derived from the tissue and cell models, we were able to accurately predict Nancy histological index scores, with a weighted kappa (κ = 0.91) and Spearman correlation (⍴ = 0.89, P < .001) when compared with pathologist consensus Nancy histological index scores. We were also able to predict histologic remission, based on the absence of neutrophil extravasation, with a high accuracy of 0.97. This work demonstrates the potential of computer vision to enable a standardized and robust assessment of ulcerative colitis histopathology for translational research and improved evaluation of disease activity and prognosis.

Impact of Endoscopic and Histologic Activity on Disease Relapse in Ulcerative Colitis

INTRODUCTION

Endoscopic healing is currently considered the main target in the management of ulcerative colitis (UC). There are conflicting data about the role of histology as a stricter treatment objective. We aim at evaluating the additional benefit of histologic remission over endoscopic remission.

METHODS

We performed a prospective observational study at the McGill University Health Center. We enrolled adult patients with UC in clinical remission for at least 3 months undergoing a colonoscopy. Endoscopic disease activity was based on the Mayo endoscopic score. Rectal biopsies were obtained, and the histologic activity was evaluated using the Geboes score (active disease defined as Geboes score ≥ 3.1) with the addition of assessing the presence of basal plasmacytosis. Patients were followed up for 12 months for disease relapse defined as a partial Mayo score of > 2. At the time of relapse or end of follow-up, all patients underwent repeat endoscopic evaluation. The primary end point was clinical relapse.

RESULTS

Two hundred fifty-three patients were included. The presence of basal plasmacytosis was associated with relapse (adjusted odd ratio = 2.07, 95% confidence interval [CI] 1.06-4.18, P = 0.042). Time to clinical relapse was significantly higher for patients with Mayo endoscopic score > 0 with adjusted hazard ratio = 2.65, 95% CI 1.31-5.39, and P = 0.007. Time to clinical relapse was not significantly higher for Geboes score ≥ 3.1 with adjusted hazard ratio = 1.29, 95% CI 0.67-2.49, and P = 0.45.

DISCUSSION

Active histologic disease did not affect time to clinical relapse in patients with UC who achieved endoscopic remission while the presence of basal plasmacytosis is associated with relapse.

Constrained multiple instance learning for ulcerative colitis prediction using histological images

BACKGROUND AND OBJECTIVE

Ulcerative colitis (UC) is an inflammatory bowel disease (IBD) affecting the colon and the rectum characterized by a remitting-relapsing course. To detect mucosal inflammation associated with UC, histology is considered the most stringent criteria. In turn, histologic remission (HR) correlates with improved clinical outcomes and has been recently recognized as a desirable treatment target. The leading biomarker for assessing histologic remission is the presence or absence of neutrophils. Therefore, the finding of this cell in specific colon structures indicates that the patient has UC activity. However, no previous studies based on deep learning have been developed to identify UC based on neutrophils detection using whole-slide images (WSI).

METHODS

The methodological core of this work is a novel multiple instance learning (MIL) framework with location constraints able to determine the presence of UC activity using WSI. In particular, we put forward an effective way to introduce constraints about positive instances to effectively explore additional weakly supervised information that is easy to obtain and enjoy a significant boost to the learning process. In addition, we propose a new weighted embedding to enlarge the relevance of the positive instances.

RESULTS

Extensive experiments on a multi-center dataset of colon and rectum WSIs, PICASSO-MIL, demonstrate that using the location information we can improve considerably the results at WSI-level. In comparison with prior MIL settings, our method allows for 10% improvements in bag-level accuracy.

CONCLUSION

Our model, which introduces a new form of constraints, surpass the results achieved from current state-of-the-art methods that focus on the MIL paradigm. Our method can be applied to other histological concerns where the morphological features determining a positive WSI are tiny and similar to others in the image.

A review on the current status and definitions of activity indices in inflammatory bowel disease: how to use indices for precise evaluation

Many clinical trials have been conducted for inflammatory bowel disease (IBD), so various clinical indices (CIs) and endoscopic indices (EIs) have also been evaluated. However, recently, with the progress of IBD management, review of established indices from previous studies, and establishment of new indices, the landscape of the use of indices in clinical trials have changed. We investigated the number and frequency of the indices adapted in recent clinical trials for ulcerative colitis (CI and EI) and Crohn's disease (CI, EI, index related to magnetic resonance imaging, index for evaluating patient-reported outcomes, and health-related quality of life). Based on the results, we selected representative indices and further reviewed their content and characteristics. Moreover, various definitions, including clinical and endoscopic response or remission, have been described by means of representative indices in clinical trials.

Diagnostic Accuracy of Fecal Calprotectin Concentration in Evaluating Therapeutic Outcomes of Patients With Ulcerative Colitis

BACKGROUND & AIMS

Histologic features of inflammation (histologic inflammation) are associated with clinical relapse in patients with ulcerative colitis (UC). Concentration of fecal calprotectin (FC) can be used to identify patients with mucosal inflammation. We aimed to assess the accuracy of FC measurements in identifying patients with histologic inflammation and to develop a model to predict outcomes of therapy.

METHODS

We performed a post hoc analysis of data from a phase 4 trial of the efficacy of multimatrix mesalamine in patients with mild to moderate UC (the MOMENTUM trial). We obtained clinical, endoscopic, and histologic data from week 8 (n = 639) and week 52 (n = 373) of the trial. We used area under the receiver operating characteristic curves to determine the accuracy and optimal cut-off values of FC in identifying patients with different therapeutic outcomes (clinical remission, endoscopic healing, deep remission, or histologic remission) at week 8 and week 52. We performed multivariable logistic regression analyses to identify factors associated with these outcomes.

RESULTS

Median FC concentrations were lower in patients who achieved outcomes of clinical remission, endoscopic healing, deep remission, or histologic remission vs patients who did not. FC concentrations identified patients with endoscopic healing and histologic remission with area under the receiver operating characteristic curve values of 0.77 and 0.76 at week 8, and 0.79 and 0.80 at week 52, respectively. The optimal FC cut-off concentrations for identification of patients with histologic remission were 75 μg/g at week 8 and 99 μg/g at week 52. In the subpopulation with an endoscopy score of 0, median FC concentrations were lower in patients with histologic remission than in patients with microscopic inflammation at week 8 (30 vs 140 μg/g; area under the receiver operating characteristic, 0.72) and week 52 (21.5 vs 134.5 μg/g; area under the receiver operating characteristic, 0.71). At both time points, the optimal FC cut-off concentration was approximately 75 μg/g. Our final prediction model for week 52 histologic remission comprised endoscopic score at week 8, FC concentration at week 8, and histologic activity at baseline and week 8.

CONCLUSIONS

A post hoc analysis of data from a phase 4 trial found that, even in patients with complete endoscopic healing of UC, FC concentration can be used to discriminate patients with ongoing microscopic inflammation from patients with histologic remission. The optimal cut-off concentration of FC is between 75 and 100 μg/g. ClinicalTrials.gov no: NCT01124149.

Impact of Subspecialty Sign-Out on Interobserver Variability and Accuracy in Gastrointestinal Pathology

Subspecialty sign-out is increasingly common in academic medical centers as well as some community practices. Reducing interobserver variability in anatomic pathology is desirable so that clinicians can select the appropriate therapy. Many departments that elect subspecialty sign-out do so with the assumption that it will improve diagnostic accuracy and interobserver variability-but does it? The literature is mixed.

Variability in the Distribution of Histological Disease Activity in the Colon of Patients with Ulcerative Colitis

BACKGROUND AND AIMS

Histological activity scores have been developed and validated. However, data on the distribution of histological inflammation within one segment in patients with ulcerative colitis [UC] are lacking. This impacts on the reliability of histological activity scores. The aim of this study was to assess the variability in histological activity within one endoscopic segment in patients with UC.

METHODS

Biopsies were taken in sequential patients with UC in three adjacent contiguous regions within a macroscopically homogeneous colonic segment. Biopsies were scored for Geboes score [GS], Robarts histological index [RHI] and Nancy histological index [NHI]. Variability was assessed by Kappa statistics for categorical outcomes and intraclass correlation coefficient [ICC] for continuous outcomes.

RESULTS

A total of 161 biopsy sets from 55 endoscopic segments of 21 patients were analysed. Endoscopically active disease was present in 45% of segments. The continuous histological scores showed excellent agreement between the different regions. The ICC for RHI in all segments was 0.974 (95% confidence interval [CI] 0.958-0.984; p < 0.0001) and 0.98 [95% CI: 0.968-0.988; p < 0.0001] for the numerically converted GS. The categorical NHI showed higher variability: κ = 0.574 [95% CI: 0.571-0.577; p < 0.0001]. In all segments the highest variability was seen in samples with NHI = 2. When dichotomizing based on histological remission, substantial agreement was seen for all scores, with κ > 0.734 for all cut-offs. The homogeneity in the distribution of histological disease activity was comparable between colonic segments.

CONCLUSION

The distribution of histological disease activity in UC follows a homogeneous pattern in different locations of one segment.

'Treat to Target' in Mild to Moderate Ulcerative Colitis: Evidence to Support this Strategy

BACKGROUND

The management of chronic conditions, above all rheumatic disease and diabetes, now incorporates a "treat to target" strategy where treatment aims to achieve objective outcomes. This is applicable in ulcerative colitis (UC) as well. Targets are demonstrated to prevent endorgan dysfunction, specifically bowel damage and its complications, and lastly colorectal cancer. Recently, the scientific community has tried to define further targets beyond those currently recommended, namely mucosal healing and clinical remission. Studies that prospectively investigated this approach in UC are scanty and a treat-to-target (T2T) algorithm is not routinely used in daily clinical practice.

OBJECTIVE

We aim to review current evidence on T2T in UC and discuss its adoption in routine clinical practice as well as in clinical trials.

METHODS

A PubMed search was conducted in February 2020 to identify published papers investigating targets' achievement rates in UC.

RESULTS

Different targets can be achieved through approved drugs for mild to moderate UC; histological remission is emerging as a robust target with respect to long-term outcomes.

CONCLUSION

Further studies to compare a T2T strategy with the traditional care are needed, particularly in the mild to moderate spectrum of disease.

Automatic, computer-aided determination of endoscopic and histological inflammation in patients with mild to moderate ulcerative colitis based on red density

BACKGROUND

The objective evaluation of endoscopic disease activity is key in ulcerative colitis (UC). A composite of endoscopic and histological factors is the goal in UC treatment. We aimed to develop an operator-independent computer-based tool to determine UC activity based on endoscopic images.

METHODS

First, we built a computer algorithm using data from 29 consecutive patients with UC and 6 healthy controls (construction cohort). The algorithm (red density: RD) was based on the red channel of the red-green-blue pixel values and pattern recognition from endoscopic images. The algorithm was refined in sequential steps to optimise correlation with endoscopic and histological disease activity. In a second phase, the operating properties were tested in patients with UC flares requiring treatment escalation. To validate the algorithm, we tested the correlation between RD score and clinical, endoscopic and histological features in a validation cohort.

RESULTS

We constructed the algorithm based on the integration of pixel colour data from the redness colour map along with vascular pattern detection. These data were linked with Robarts histological index (RHI) in a multiple regression analysis. In the construction cohort, RD correlated with RHI (r=0.74, p<0.0001), Mayo endoscopic subscores (r=0.76, p<0.0001) and UC Endoscopic Index of Severity scores (r=0.74, p<0.0001). The RD sensitivity to change had a standardised effect size of 1.16. In the validation set, RD correlated with RHI (r=0.65, p=0.00002).

CONCLUSIONS

RD provides an objective computer-based score that accurately assesses disease activity in UC. In a validation study, RD correlated with endoscopic and histological disease activity.

Review article: faecal calprotectin and histologic remission in ulcerative colitis

BACKGROUND

Histologic healing is emerging as a new therapeutic goal in both routine practice and clinical trials in ulcerative colitis (UC). However, it requires repeated endoscopies and biopsies. Faecal calprotectin is a non-invasive marker of mucosal healing (endoscopic and histologic healing).

AIM

To conduct a systematic review to clarify the correlation between faecal calprotectin levels and histologic activity in UC patients.

METHODS

We searched PubMed/MEDLINE, EMBASE and Web of Science through September 2019 to identify studies in patients with confirmed diagnosis of UC, reporting the correlation between faecal calprotectin levels and histologic analysis.

RESULTS

Twelve studies enrolling 1168 patients were included in the final review. Histologic remission was defined according to nonvalidated scores in five articles and using partially validated scores in seven articles. Faecal calprotectin values were measured in 6 of 12 studies (50%) with the same kit, while the remaining six studies adopted individually different kits. A clear correlation between faecal calprotectin levels and histology was showed in all included studies. Eleven different faecal calprotectin cut-off points were identified to distinguish histological remission from histological activity, ranging from 40.5 to 250 μg/g.

CONCLUSIONS

Faecal calprotectin can be used to predict histologic remission in patients with UC, but the cut-off level varies across studies, according to the test used to measure this biomarker and according to the definition of histologic remission. Larger prospective studies using validated histologic indexes are needed to identify a globally accepted faecal calprotectin cut-off level to discriminate between histologic remission and histologically active disease.

Histological Remission in Ulcerative Colitis: Under the Microscope Is the Cure

In recent years, the therapeutic goals in ulcerative colitis (UC) have become increasingly stringent. Histological features seem to be a reliable predictor of disease outcomes after therapy, and histological remission (HR) is the new frontier in the treatment of UC. Here, we first provide a historical perspective before reviewing indexes in the era of biologics; histology as a treatment goal in UC trials; the poor correlation between symptoms, endoscopy, and histology; and the impact of histology on disease outcomes. HR seems to be a promising end point for the treatment of UC because it is typically associated with better outcomes. Two new validated indexes are available to assess histology more accurately in trials, and they may also be applicable to clinical practice. Additional interventional trials are now necessary to establish definitions of HR and its potential for disease modification.

Complete histologic normalisation is associated with reduced risk of relapse among patients with ulcerative colitis in complete endoscopic remission

BACKGROUND

Clinical and endoscopic remission are treatment targets in ulcerative colitis (UC). The value of histologic healing in altering clinical outcomes among patients with complete endoscopic healing is not well established.

AIM

To quantify the association between histologic activity and clinical relapse among patients with UC who were in complete endoscopic remission.

METHODS

This study included patients with UC from a prospective registry who were in complete endoscopic remission. Histologic activity was quantified by a senior gastrointestinal pathologist. Histologic activity was defined as lack of normalisation (Geboes score > 0) as well as histologically active disease (Geboes score ≥2.1 and ≥3.1). The primary outcome was clinical relapse within 2 years. Multivariable regression adjusting for potential confounders examined the independent predictive value of histologic changes.

RESULTS

The study included 83 patients (51% women) (median age 44 years; median disease duration 11 years). Forty-one (49%) had complete histologic normalisation. Within two years, 26 (31%) experienced clinical relapse. Patients with complete histologic normalisation were less likely to experience relapse (5/41, 12%) compared to those without normalisation (21/42, 50%, P < 0.001) (multivariable OR 7.22, 95% confidence interval (CI) 2.48-24.70) by the Geboes score. The individual components of the Geboes score predictive of relapse were architectural changes (P = 0.03) and increased chronic inflammatory infiltrate (P < 0.001).

CONCLUSIONS

Complete histologic healing using the Geboes score was associated with reduced rates of clinical relapse among patients with UC in endoscopic remission.

Histological healing: should it be considered as a new outcome for ulcerative colitis?

Introduction: Currently, mucosal healing is considered as a composite treatment end-point in inflammatory bowel disease (IBD) since it has been demonstrated to improve disease-related outcomes. The definition of mucosal healing has evolved and current evidence suggests that in addition to endoscopic healing the achievement of histological remission (HR) represents a potential novel target in the management of IBD in relation to better long-term disease outcomes.Areas covered: We aimed to review the current literature on HR in ulcerative colitis and discuss its limitations and advantages when adopting this potential new target as an ultimate treatment outcome in clinical trials and routine clinical practice.Expert opinion: HR is achievable in UC with different rates in conventional therapies, biological and novel drugs. Targeting HR in UC lowers the risk of hospitalizations, colectomy, and colorectal cancer. HR occurs later than endoscopic remission, longer treatment courses are associated with higher HR assessment. This might imply modifying monitoring time schedules and algorithms. Prospective data are needed to support histological healing as a new treatment target in UC.

Can advanced endoscopic techniques for assessment of mucosal inflammation and healing approximate histology in inflammatory bowel disease?

The targets of therapy in inflammatory bowel disease have transformed in the last few years. The standard definition of mucosal healing assessed using white light standard definition endoscopy is being challenged because even when endoscopy suggests mucosal healing, the presence of histological activity can often still be observed. Of note, microscopic signs of inflammation correlate with clinical outcomes such as risk of relapse, hospitalization and colorectal cancer. Therefore, histological healing has increasingly become an important target to achieve. Advanced endoscopic technologies have been developed and many are starting to be adopted in daily clinical practice. They can provide a more detailed view of the mucosal and vascular architecture almost at the histology level, including crypt, vessel architecture and cellular infiltration. So, these can provide a more accurate definition of mucosal and histological healing. In this review we focus on new advanced endoscopic techniques, and how these have the potential to reduce the gap between histological and mucosal healing.

Indoleamine 2,3-dioxygenase-dependent expansion of T-regulatory cells maintains mucosal healing in ulcerative colitis

BACKGROUND

Dendritic cell (DC)-derived indolamine 2,3-dioxygenase (IDO) degrades tryptophan to kynurenine, which promotes conversion of inflammatory T cells in immunosuppressive regulatory T cells (Tregs). We analyzed the significance of the IDO:Treg axis for inducing and maintaining mucosal healing in ulcerative colitis (UC).

METHODS

Dextran sodium sulphate (DSS)-induced colitis in BALB/c mice (model for mucosal healing) and C57BL/6 mice (model for persistent disease) was used. Serum, fecal samples and colon-infiltrating immune cells of 65 patients with UC with mucosal healing or persistent colitis were analyzed.

RESULTS

Significantly higher serum levels of kynurenine and downregulated inflammatory cytokines were noticed in DSS-treated BALB/c mice compared with C57BL/6 mice. Increased IDO activity and attenuated capacity for antigen presentation and production of inflammatory cytokines, observed in BALB/c DCs, was followed by a significantly lower number of inflammatory T helper 1 (Th1) and Th17 cells and a notably increased number of Tregs in the colons of DSS-treated BALB/c mice. DCs and Tregs were crucially important for the maintenance of mucosal healing since their depletion aggravated colitis. Mucosal healing, followed by an increase in kynurenine and intestinal Tregs, was re-established when BALB/c DCs were transferred into DC-depleted or Treg-depleted DSS-treated BALB/c mice. This phenomenon was completely abrogated by the IDO inhibitor. Significantly higher serum and fecal levels of kynurenine, accompanied by an increased presence of intestinal Tregs, were noticed in patients with UC with mucosal healing and negatively correlated with disease severity, fecal calprotectin, colon-infiltrating interferon γ and interleukin-17-producing cells, serum and fecal levels of inflammatory cytokines.

CONCLUSION

IDO-dependent expansion of endogenous Tregs should be further explored as a new approach for the induction and maintenance of mucosal healing in patients with UC.