ECCO Position on Harmonisation of Crohn's Disease Mucosal Histopathology

Effects of Mirikizumab on Histologic Resolution of Crohn's Disease in a Randomized Controlled Phase 2 Trial

BACKGROUND & AIMS

Histologic evaluation of mucosal healing in Crohn's disease is an evolving treatment target. We evaluated histologic outcomes for mirikizumab efficacy and associations with endoscopic and 1-year outcomes.

METHODS

Biopsy specimens from 1 ileal and 4 colonic segments were evaluated at weeks 0, 12, and 52 from each of the 170 SERENITY participants. Criteria for the weeks 12 and 52 histologic response were no epithelial neutrophils or epithelial damage, or >50% decrease in either the Robarts Histopathology Index or the active Global Histologic Disease Activity Score, and remission (no mucosal neutrophils and no epithelial damage) had to be met in all biopsy specimens. Agreement was evaluated between histologic and endoscopic end points. Associations between 1-year outcomes and week 12 histologic and endoscopic response were evaluated.

RESULTS

At week 12, 1000 mg mirikizumab resulted in greater rates of histologic response (66% vs 27%; P < .001) and remission (26% vs 6%; P < .01) than placebo. Rates were numerically similar at 1 year (mirikizumab pooled response, 46%-69%; remission, 13%-31%). Agreement between week 12 histologic and endoscopic response was 69% (Cohen's kappa coefficient [κ] = 0.40) and remission was 83% (κ = 0.38) in all pooled arms, including placebo. At 1 year, the percentage of participants who received any dose of mirikizumab and achieved endoscopic remission differed by their week 12 response: histologic (20%), endoscopic (25%), combined histology-endoscopy (45%), or neither (4%) (P = .003).

CONCLUSIONS

In a post hoc analysis of phase 2 data, mirikizumab induced and sustained histologic response and remission in Crohn's disease over 52 weeks. Early combined histologic-endoscopic response was associated with endoscopic remission after 1 year of treatment with mirikizumab (ClinicalTrials.gov NCT02891226).

Claudin-2: A marker for a better evaluation of histological mucosal healing in inflammatory bowel diseases

BACKGROUND

Histological mucosal healing has become a paramount target goal to achieve in the treatment of inflammatory bowel diseases. However, there is still a lack of agreement on the best way to reach this goal, since numerous histological scores are available worldwide.

AIMS

We investigated whether claudin-2, a member of claudin family involved in the regulation of intestinal tight junctions, might be useful to assess the presence of active disease in patients with inflammatory bowel diseases.

METHODS

Biopsies from 123 patients with ulcerative colitis, Crohn's disease, infectious colitides and irritable bowel syndrome patients where tested with immunohistochemistry for claudin-2.

RESULTS

Claudin-2 appeared to be a very sensitive marker of disease activity in inflammatory bowel diseases, but was negative in the other kinds of patients. In addition, immunohistochemistry for claudin-2 showed good reproducibility by different pathologists.

CONCLUSIONS

Should these findings be confirmed in more numerous cohorts of patients, and especially in those with minimal or focal residual disease activity, this simple assessment could be useful in the routine daily practice to facilitate the task of pathologists and clinicians in the diagnosis and management of patients with inflammatory bowel diseases.

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.

How Artificial Intelligence Will Transform Clinical Care, Research, and Trials for Inflammatory Bowel Disease

Artificial intelligence (AI) refers to computer-based methodologies that use data to teach a computer to solve pre-defined tasks; these methods can be applied to identify patterns in large multi-modal data sources. AI applications in inflammatory bowel disease (IBD) includes predicting response to therapy, disease activity scoring of endoscopy, drug discovery, and identifying bowel damage in images. As a complex disease with entangled relationships between genomics, metabolomics, microbiome, and the environment, IBD stands to benefit greatly from methodologies that can handle this complexity. We describe current applications, critical challenges, and propose future directions of AI in IBD.

Monomeric C-Reactive Protein Potential Utilization in the Histological Assessment of Inflammatory Bowel Disease (IBD) Patients

Introduction Inflammatory bowel diseases (IBDs), including ulcerative colitis (UC) and Crohn's disease (CD), represent chronic progressive inflammatory gastrointestinal disorders, without a single reference standard for their diagnosis. The histological assessment gained an important role in accurately measuring disease activity, and mucosal healing (MH) was recently proposed to be an ideal treatment goal for patients with IBD because of its favorable prognosis, with a lower risk of recurrence or surgical treatment. This paper aims to add to the histological classical findings for IBD patients the identification of the monomeric form of the C-reactive protein (mCRP) as a supplementary marker that could be stained at the level of tissue samples and could be correlated with the pathogenic mechanism. Methods Two groups of 10 patients were each selected for the study, for both UC and CD, together with a control group. All samples collected through digestive endoscopy were analyzed by using H&E-stained slides, followed by immunohistochemical examination with antibodies to mCRP (M8C10), and markers of inflammatory activity through CD3, CD45(leukocyte common antigen (LCA)), CD138/syndecan-1 and CD68. Results For the CD study group, all histological elements identified with H&E and afterward stained with CD138, CD68, CD3, and CD45/LCA were correlated with the standards imposed by the European Crohn's and Colitis Organization (ECCO). For the group of patients with UC, histological images obtained with H&E and IHC stainings also confirmed the recommendation of ECCO. The main cells considered in the literature as histological markers for IBD are neutrophils, lymphocytes, and plasmocytes, stained in our study with CD45/LCA, CD3, and CD138. For all 20 cases of IBD (UC and CD), the staining with anti-Ab8C10 antibodies for mCRP was positive, while negative results were noticed within the control group. An mCRP protein visualized with anti-Ab8C10 antibodies presented an intracytoplasmatic localization in the neutrophils, plasma cells, lymphocytes, and macrophages from the lamina propria and glandular epithelium, without expression in endothelial cells. Conclusions Our study represents one of the first papers that identifies the localization of mCRP molecules within the intestinal mucosa of patients with IBD (both UC and CD) by using immunohistochemistry (IHC) staining. This finding opens a new perspective for considering mCRP as a marker correlated with histological disease activity and/or definition of histological remission in IBD.

Factors Predicting Loss of Remission in Crohn's Disease Patients in Endoscopic Remission in the Real World: Results From TARGET-IBD

BACKGROUND

There is limited evidence that histologic remission improves outcomes in Crohn's disease (CD). We aimed to characterize a cohort of patients with CD in endoscopic remission and explore factors associated with subsequent loss of remission (LOR).

METHODS

In total, 4474 patients were enrolled in TARGET-IBD, a longitudinal, observational cohort study. Patients with a normal steroid-free colonoscopy (index) were defined as "in endoscopic remission" and were followed for LOR, defined as presence of inflammation, erosion, ulceration, or stricturing on a subsequent colonoscopy or commencement of steroids. Histologic activity was dichotomized using standard of care reports for active inflammation. Unadjusted and multivariable-adjusted Cox proportional hazards regression models were used to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) of LOR in relation to independent variables.

RESULTS

Of 658 patients with CD with steroid-free endoscopic remission, the majority were female (57%), white (83%), non-Hispanic (93%); 20% had ileal and 20% isolated colonic disease. Inflammatory (B1) disease was the most common phenotype (43%). Of these 658 patients, 257 (39%) had histologic inflammation on index colonoscopy. Histologic inflammation at index colonoscopy was associated with nearly twice the LOR risk (HR 1.96, 95% CI: 1.50-2.57) with median time to relapse of 1.20 years. Biologic use at index was associated with lower LOR risk (monotherapy, HR 0.61, 95% CI: 0.45-0.82; combination therapy, HR 0.43, 95% CI: 0.28-0.66).

CONCLUSIONS

Active histologic inflammation despite endoscopic remission, and lack of biologic use were independently associated with risk of subsequent LOR, providing evidence that histologic remission may impart improved outcomes in patients with CD.

Histologic Remission in Inflammatory Bowel Disease and Female Fertility: A Nationwide Study

BACKGROUND & AIMS

Inflammatory bowel disease (IBD) is linked to reduced female fertility, but it is unclear how fertility rates vary by histologic disease activity.

METHODS

Nationwide IBD cohort of Swedish women aged 15 to 44 years. We examined fertility rates during periods with vs without histologic inflammation (n = 21,046; follow-up, 1990-2016) and during periods with vs without clinical activity (IBD-related hospitalization, surgery, or treatment escalation) (n = 24,995; follow-up, 2006-2020). Accounting for sociodemographics and comorbidities, we used Poisson regression to estimate adjusted fertility rate ratios (aFRRs) for live births conceived during 12-month periods of histologic inflammation (vs histologic remission) and 3-month periods of clinically active IBD (vs quiescent IBD).

RESULTS

During periods with vs without histologic inflammation, there were 6.35 (95% confidence interval [CI], 5.98-6.73) and 7.09 (95% CI, 6.48-7.70) live births conceived per 100 person-years of follow-up, respectively, or 1 fewer child per 14 women with 10 years of histologic inflammation (aFRR, 0.90; 95% CI, 0.81-1.00). In women with histologic inflammation, fertility was similarly reduced in ulcerative colitis (UC) (aFRR, 0.89 [95% CI, 0.78-1.02]) and Crohn's disease (CD) (aFRR, 0.86 [95% CI, 0.72-1.04]). Clinical IBD activity was associated with an aFRR of 0.76 (95% CI, 0.72-0.79) or 1 fewer child per 6 women with 10 years of clinical activity. Fertility was reduced in clinically active UC (aFRR, 0.75 [95% CI, 0.70-0.81]) and CD (aFRR, 0.76 [95% CI, 0.70-0.82]). Finally, among women with clinically quiescent IBD, histologic inflammation (vs histologic remission) was associated with reduced fertility (aFRR, 0.85 [95% CI, 0.73-0.98]).

CONCLUSIONS

An association between histologic and clinical activity and reduced female fertility in CD and UC was found. Notably, histologic inflammation was also linked to reduced fertility in women with clinically quiescent IBD.

Deep Learning Models Capture Histological Disease Activity in Crohn's Disease and Ulcerative Colitis with High Fidelity

BACKGROUND AND AIMS

Histological disease activity in inflammatory bowel disease [IBD] is associated with clinical outcomes and is an important endpoint in drug development. We developed deep learning models for automating histological assessments in IBD.

METHODS

Histology images of intestinal mucosa from phase 2 and phase 3 clinical trials in Crohn's disease [CD] and ulcerative colitis [UC] were used to train artificial intelligence [AI] models to predict the Global Histology Activity Score [GHAS] for CD and Geboes histopathology score for UC. Three AI methods were compared. AI models were evaluated on held-back testing sets, and model predictions were compared against an expert central reader and five independent pathologists.

RESULTS

The model based on multiple instance learning and the attention mechanism [SA-AbMILP] demonstrated the best performance among competing models. AI-modelled GHAS and Geboes subgrades matched central readings with moderate to substantial agreement, with accuracies ranging from 65% to 89%. Furthermore, the model was able to distinguish the presence and absence of pathology across four selected histological features, with accuracies for colon in both CD and UC ranging from 87% to 94% and for CD ileum ranging from 76% to 83%. For both CD and UC and across anatomical compartments [ileum and colon] in CD, comparable accuracies against central readings were found between the model-assigned scores and scores by an independent set of pathologists.

CONCLUSIONS

Deep learning models based upon GHAS and Geboes scoring systems were effective at distinguishing between the presence and absence of IBD microscopic disease activity.

Histologic Activity in Inflammatory Bowel Disease and Risk of Serious Infections: A Nationwide Study

BACKGROUND & AIMS

Individuals with inflammatory bowel disease (IBD) are at increased risk of serious infections, but whether this risk varies by histologic disease activity is unclear.

METHODS

This was a national population-based study of 55,626 individuals diagnosed with IBD in 1990 to 2016 with longitudinal data on ileocolorectal biopsy specimens followed up through 2016. Serious infections were defined as having an inpatient infectious disease diagnosis in the Swedish National Patient Register. We used Cox regression to estimate hazard ratios (HRs) for serious infections in the 12 months after documentation of histologic inflammation (vs histologic remission), adjusting for social and demographic factors, chronic comorbidities, prior IBD-related surgery, and hospitalization. We also adjusted for IBD-related medications in sensitivity analyses.

RESULTS

With histologic inflammation vs remission, there was 4.62 (95% CI, 4.46-4.78) and 2.53 (95% CI, 2.36-2.70) serious infections per 100 person-years of follow-up, respectively (adjusted HR [aHR], 1.59; 95% CI, 1.48-1.72). Histologic inflammation (vs remission) was associated with an increased risk of serious infections in ulcerative colitis (aHR, 1.68; 95% CI, 1.51-1.87) and Crohn's disease (aHR, 1.59; 95% CI, 1.40-1.80). The aHRs of sepsis and opportunistic infections were 1.66 (95% CI, 1.28-2.15) and 1.71 (95% CI, 1.22-2.41), respectively. Overall, results were consistent across age groups, sex, and education level, and remained largely unchanged after adjustment for IBD-related medications (aHR, 1.47; 95% CI, 1.34-1.61).

CONCLUSIONS

Histologic inflammation of IBD was an independent risk factor of serious infections, including sepsis, suggesting that achieving histologic remission may reduce infections in IBD. The study was approved by the Stockholm Ethics Review Board (approval numbers 2014/1287-31/4, 2018/972-32, and 2021-06209-01).

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.

The Histology-Driven Differential Diagnosis in Bowel Inflammatory Conditions Is Not All That Obvious: Evidence from a Survey Based on Digital Slides

(1) Background: when the pathologist faces histologic slides from colonoscopies in daily practice, given the large number of entities and etiologies under inflammatory bowel conditions, in-depth definition of the histological spectrum and the recommendations of current guidelines are often not enough to conclusively define a diagnostic framework. Histological patterns should be organized hierarchically in flowcharts that consider the correlation with clinical data. We conducted an online survey asking a group of gastroenteropathologists to apply a pattern classification based on the most significant lesions in colitis differential diagnosis: crypt distortion and activity. (2) Methods: digital slides from 20 endoscopy samples were analyzed by twenty pathologists and classified according to the occurrence of crypt distortion (nondestructive-destructive colitis) and subsequently to the evidence of activity (ND1-2-3, D1-2). (3) Results: in 8 out of 20 (40%) cases, the participants reached a full agreement regarding the evaluation of crypt distortion (5 cases: nondestructive colitis; 3 cases: destructive colitis). The calculated agreement was k = 0.432. In the second-level quiz (ND1-2-3 and D1-2), full agreement between participants was achieved for 7 of the 28 (25%) possible classifications, with k = 0.229. (4) Conclusions: The findings from this survey are indicative of an unexpectedly low consensus, even among dedicated pathologists, about the recognition of histological changes that are commonly considered critical lesions in the histologic identification of bowel non-neoplastic diseases. In our opinion, these divergences imply a significant risk of misdiagnosis of bowel inflammatory conditions, hampering the usefulness of histological assessment.

Emerging strategy towards mucosal healing in inflammatory bowel disease: what the future holds?

For decades, the therapeutic goal of conventional treatment among inflammatory bowel disease (IBD) patients is alleviating exacerbations in acute phase, maintaining remission, reducing recurrence, preventing complications, and increasing quality of life. However, the persistent mucosal/submucosal inflammation tends to cause irreversible changes in the intestinal structure, which can barely be redressed by conventional treatment. In the late 1990s, monoclonal biologics, mainly anti-TNF (tumor necrosis factor) drugs, were proven significantly helpful in inhibiting mucosal inflammation and improving prognosis in clinical trials. Meanwhile, mucosal healing (MH), as a key endoscopic and histological measurement closely associated with the severity of symptoms, has been proposed as primary outcome measures. With deeper comprehension of the mucosal microenvironment, stem cell niche, and underlying mucosal repair mechanisms, diverse potential strategies apart from monoclonal antibodies have been arising or undergoing clinical trials. Herein, we elucidate key steps or targets during the course of MH and review some promising treatment strategies capable of promoting MH in IBD.

To STRIDE or not to STRIDE: a critique of "treat to target" in Crohn´s disease

INTRODUCTION

The STRIDE consensus suggested to focus on mucosal healing, based on biomarkers and endoscopy, in addition to clinical endpoints as treatment target. This narrative review provides a critique of this concept in Crohn´s disease.

AREAS COVERED

We analyze and discuss the limitations of endpoints as targets, their currently limited achievability, and the controversial evidence relating to 'treat to target.' The relevant publications in Pubmed were identified in a literature review with the key word 'Crohn´s disease.'

EXPERT OPINION

All targets and endpoints have their limitations, and, even if reached, not all have unequivocally been shown to improve prognosis. The major deficiency of STRIDE is not only the lack of validation and agreement upon endpoints but little evidence of their achievability in a sizable proportion of patients by dose or timing adjustments or switching the medication. Above all, the concept should be based on clear evidence that patients indeed benefit from appropriate escalation of treatment and relevant controlled studies in this regard have been controversial. Until the STRIDE approach is proven to be superior to standard treatment focusing on clinical well-being, the field should remain reluctant and expect more convincing evidence before new targets are approved.

Letter: The importance of histological assessment-a further stride in STRIDE. Authors' reply

This article is linked to Dignass et al papers. To view these articles, visit https://doi.org/10.1111/apt.17622 and https://doi.org/10.1111/apt.17717

Evaluation of Disease Activity in Inflammatory Bowel Disease: Diagnostic Tools in the Assessment of Histological Healing

Inflammatory bowel disease (IBD) comprises two types of chronic intestinal disorders: Crohn's disease and ulcerative colitis. In long-standing ulcerative colitis disease activity, histological persistent inflammation has been linked to an increased risk of relapse, and long-term corticosteroid use, even when endoscopic remission is reached. In Crohn's disease, the discontinuous nature of lesions and transmural inflammation have limited the standardized histological assessment. The current evidence from research proposes that besides clinical and endoscopic healing, the achievement of histological healing constitutes an endpoint to assess disease activity and remission in IBD patients concerning better long-term disease outcomes. Histological alterations may persist even in the absence of endoscopic lesions. For these reasons, new advanced techniques promise to revolutionize the field of IBD by improving the endoscopic and histologic assessment, disease characterization, and ultimately patient care, with an established role in daily practice for objective assessment of lesions. This review outlines the importance of including microscopic evaluation in IBD, highlighting the clinical benefits of a deep state of disease remission using validated diagnostic methods and scoring systems for daily clinical practice.

Defining Biological Remission in Crohn's Disease: Interest, Challenges and Future Directions

In Crohn's disease, the treat-to-target strategy has been greatly encouraged and has become a standard of care. In this context, defining the target [remission] constitutes a major stake and is fuelling the literature. Currently, clinical remission [symptom control] is no longer the only objective of treatments since it does not allow to closely control inflammation-induced tissue damage. The introduction of endoscopic remission as a therapeutic target clearly represented progress but this examination remains invasive, costly, not well accepted by patients and does not allow tight control of disease activity. More fundamentally, morphological techniques [e.g. endoscopy, histology, ultrasonography] are limited since they do not evaluate the biological activity of the disease but only its consequences. Besides, emerging evidence suggests that biological signs of disease activity could better guide treatment decisions than clinical parameters. In this context, we stress the necessity to define a novel treatment target: biological remission. Based on our previous work, we propose a conceptual definition of biological remission which goes beyond the classical normalization of inflammatory markers [C-reactive protein and faecal calprotectin]: absence of biological signs associated with the risk of short-term relapse and mid-/long-term relapse. The risk of short-term relapse seems essentially to be characterized by a persistent inflammatory state while the risk of mid-/long-term relapse implies a more heterogeneous biology. We discuss the value of our proposal [guiding treatment maintenance, escalation or de-escalation] but also the fact that its clinical implementation would require overcoming major challenges. Finally, future directions are proposed to better define biological remission.

Additional information obtained from mucosal biopsies is limited after pan-enteric capsule endoscopy in patients with suspected Crohn's disease

Background and study aims Pan-enteric capsule endoscopy (CE) is an emerging alternative to ileo-colonoscopy for diagnosing Crohn's disease (CD). However, CE does not offer the opportunity to take biopsies to support the diagnosis. This study examined the additional information obtained with mucosal biopsies and the feasibility of CE as a single diagnostic procedure. Patients and methods This retrospective study was based on a prospective, blind multicenter trial in which patients with suspected CD were examined with ileo-colonoscopy plus segmental biopsies and CE. Histopathological findings were compared to the result of CE. Results A total of 107 patients with a complete CE were included in the analysis. CE was consistent with CD in 44 patients (41.1%) and ulcerative colitis in 10 patients (9.3%). Histopathology confirmed the result of CE in 39.3% of patients and added new diagnostic information in 6.5% of patients. A CE consistent with CD was histologically confirmed in 20.5% of patients. Biopsies most often showed non-specific inflammation (61.4%). Only one patient with a normal CE had a specific histological diagnosis (microscopic colitis). Biopsies altered the diagnosis of ulcerative colitis to CD in two patients, and in two patients with a normal CE, biopsies showed CD or ulcerative colitis. In one patient with lymphoma in the terminal ileum and cecum, CE was misinterpreted as CD. Conclusions In patients with suspected CD and an evident result of CE, the additional information obtained from biopsies is limited, and CE as a single diagnostic procedure might be feasible in selected patients. Biopsies are warranted, however, in patients with an atypical endoscopic appearance or suspected malignancy.

Real-World Endoscopic and Histologic Outcomes in Ulcerative Colitis Patients: A Retrospective Cohort Study

BACKGROUND

Histologic activity has emerged as an aspirational therapeutic goal in ulcerative colitis management. It is not yet a formal treatment target in ulcerative colitis. However, it could be used as an adjunct to mucosal healing to represent a deeper level of healing. We investigated mucosal and histologic remission rates and potential predictors of these outcomes in a cohort of UC patients.

METHODS

We conducted a retrospective analysis of data collected from UC patients enrolled in an ongoing prospective cohort study. Mucosal healing was defined as Mayo endoscopic score = 0.

RESULTS

A total of 131 patients with ulcerative colitis were enrolled in our study and were prospectively followed for a median length of 2 years (range 0-5 years), totaling 266 study visits. Mucosal healing was recorded for 27 patients at 70 (26%) different study visits. For patients with mucosal healing, histologic remission was achieved in 18/27 (66%) patients. On univariate analysis, sustained clinical remission, SIBDQ scores ≥ 5.5, CRP ≤ 5 mg/dL and absence of corticotherapy were associated with mucosal healing and SIBDQ scores ≥ 5.5 and CRP ≤ 5 mg/dL with histologic healing, respectively. After logistic regression analysis, none of the investigated factors were associated with mucosal and histologic healing. The number of CD8+ intraepithelial lymphocytes (IELs) was significantly greater than the number of CD4+ IELs in periods of disease activity, as well as during mucosal healing (p < 0.01 in both cases).

CONCLUSIONS

Mucosal healing and histologic remission rates are low in real-life settings. The results of univariate analysis indicate that a good quality of life (SIBDQ score) and normal inflammatory markers (CRP) are associated with mucosal and histologic healing. However, frequently used patient- and disease-related factors, including mucosal healing, are not reliable predictors for histologic remission. Greater CD8+ lymphocyte involvement and higher CD8+/CD4+ distribution can have a meaningful impact on understanding the pathogenesis and natural history of ulcerative colitis, as well as future treatment options for lymphocyte-targeting medications.

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.

[Inflammatory bowel diseases: Scoring and pathological reports optimization]

The two main forms of inflammatory bowel disease (IBD) are ulcerative colitis (UC) and Crohn's disease (CD). Both diseases have inflammatory flare-ups that alternate with periods of remission. The pathologist may examine biopsies of the digestive tract from IBD patients in different contexts: at the time of the initial diagnosis, in the event of a disease flare-up in order to differentiate a flare of the disease from another cause, particularly an infectious one, and during the long term follow-up of the disease in order to detect the occurrence of dysplastic lesions. Pathologists are increasingly involved in the evaluation of inflammatory activity during the follow-up of IBD patients. The therapeutic management of IBD has evolved significantly and the emergence of new treatments allows a global approach targeting endoscopic mucosal healing. However, mucosal healing is not always correlated with histological healing. Numerous studies have shown the value of histological evaluation during follow-up. A higher score for histological activity in ulcerative colitis predicts a higher likelihood of neoplasia. Histological activity is a better predictor than endoscopic inflammation of the risk. In UC, histological remission may be a long-term therapeutic goal but its role in CD remains unclear. Different scores have been developed to quantify the inflammatory activity of IBD patients and the response to treatment. The aim of this review is to present the main activity scores used in the follow-up of IBD, their interest, their evaluation and their limitations.

Prevalence and Correlations of Gastrointestinal Symptoms with Endoscopic and Histologic Mucosal Healing in Crohn's Disease

To characterize the associations between clinical disease activity with endoscopic and histologic (endo-histologic) mucosal healing in Crohn's disease (CD), we performed a secondary analysis of prospectively collected data on 424 ileocolonoscopies from 258 unique adults at a tertiary referral center from 2014-2021. One-third (34%, 25/73) of patients in endoscopic-histologic remission reported gastrointestinal (GI) symptoms. The 2-item patient-reported outcome measure (PRO-2) for abdominal pain and stool frequency correlated weakly with endoscopic (Simple Endoscopic Score for Crohn's Disease; r =0.17, 95% CI 0.08-0.26, p=0.0003) and histologic disease activity (Global Histologic Disease Activity Score; r =0.14, 95% CI 0.03-0.24, p=0.015). Overall, GI symptoms correlate poorly with endo-histologic disease activity.

Histological remission in inflammatory bowel disease and risk of adverse pregnancy outcomes: A nationwide study

BACKGROUND

Inflammatory bowel disease (IBD) has been linked to adverse pregnancy outcomes, but it is unclear how risks vary by histological activity.

METHODS

We performed a nationwide study of Swedish women diagnosed with IBD 1990-2016 and a pre-pregnancy (<12 months) colorectal biopsy with vs. without histological inflammation (1223 and 630 births, respectively). We also examined pregnancy outcomes in 2007-2016 of women with vs. without clinically active IBD (i.e., IBD-related hospitalization, surgery, or medication escalation) <12 months before pregnancy (2110 and 4993 births, respectively). Accounting for smoking, socio-demographics, and comorbidities, generalized linear models estimated adjusted risk ratios (aRRs) for preterm birth (<37 gestational weeks) and small-for-gestational age (SGA, <10th percentile weight for age).

FINDINGS

Of infants to women with vs. without histological inflammation, 9.6% (n = 117) and 6.5% (n = 41) were preterm, respectively (aRR = 1.46; 95%CI = 1.03-2.06). Histological inflammation was associated with preterm birth in ulcerative colitis (UC) (aRR = 1.64; 95%CI = 1.07-2.52), especially extensive colitis (aRR = 2.37; 95%CI = 1.12-5.02), but not in Crohn's disease (aRR = 0.99; 95%CI = 0.55-1.78). Of infants to women with vs. without histological inflammation, 116 (9.6%) and 56 (8.9%), respectively, were SGA (aRR = 1.09; 95%CI = 0.81-1.47). Clinically active disease before pregnancy was linked to preterm birth (aRR = 1.42; 95%CI = 1.20-1.69), but not to SGA birth (aRR = 1.13; 95%CI = 0.96-1.32). Finally, of infants to women without clinical activity, histological inflammation was not significantly associated with preterm birth (aRR = 1.20; 95%CI = 0.68-2.13).

INTERPRETATION

Histological and clinical activity in IBD, especially in UC, were risk factors for preterm birth. Further research is needed to determine the importance of pre-pregnancy histological activity in women without clinically-defined disease activity.

FUNDING

The Swedish Society of Medicine.

Impact of Crohn's Disease Therapies on Histology in Randomized Controlled Trials: Systematic Review With Meta-analysis

BACKGROUND

The effectiveness of Crohn's disease treatments for inducing histological outcomes has not been addressed systematically. We performed a systematic review and meta-analysis of randomized controlled trials in Crohn's disease to assess the impact of therapies on mucosal histopathology.

METHODS

Databases (MEDLINE, CENTRAL, Web of Science, EMBASE) were searched for randomized controlled trials including adult patients and evaluating histological outcomes. Risk of bias was evaluated using the Critical Appraisal Skills Programme. Histological outcomes, pooled frequencies, pooled odds ratios, and standard mean differences of the histological scores were compared between the intervention and placebo groups using a random-effects model.

RESULTS

Out of 2070 records, 10 studies were included. The quality of the studies ranged from moderate to high, but they were clinically and methodologically diverse. All interventions were superior to placebo. Histological response was achieved by 68% of patients, and 38% achieved remission. Pooled odds ratio for histological remission in patients receiving intervention vs placebo was 4.14 (95% CI, 2.28-7.50; I2 0%; P < .01). Heterogeneity in histological response estimates was significant, and subgroup analysis of the odds ratio results was limited by the low number of studies per group. The standard mean difference of histological scores was higher for patients receiving intervention in both induction and maintenance studies (-2.95; 95% CI, -4.17 to -1.74; I2 83% P < .00; and -2.58; 95% CI, -3.89 to -1.27; I2 56% P < .00).

CONCLUSIONS

Crohn's disease therapies are effective for achieving histological outcomes. Adherence to recently published consensus on histopathology harmonization assessment in Crohn's disease would facilitate adequate comparison between studies in the future.

Histological Scores in Patients with Inflammatory Bowel Diseases: The State of the Art

The histological assessment has been advocated as a detailed and accurate measure of disease activity in inflammatory bowel diseases (IBD). In ulcerative colitis (UC), histological activity has been demonstrated to be associated with higher rates of relapse, prolonged corticosteroid use and long-term complications, even when endoscopic remission is achieved. Therefore, histological healing may represent a potential treatment target. Several histological scores have been developed and are available today. The Robarts histopathology index (RHI) and the Nancy index (NI) are the only two recommended by the European Crohn’s and Colitis Organization (ECCO) for use in patients with UC. Conversely, in Crohn’s disease (CD), the discontinuous nature of lesions has limited standardized histological assessment. Most of the available histological scoring systems in CD are complex and not validated. The aim of this review is to comprehensively summarize the latest evidence regarding histological scoring systems in IBD. We guide the reader through understanding the importance of an accurate microscopic evaluation using validated scoring systems, highlighting the strengths and pitfalls of each score. The priorities of future research needs are also addressed.