Evolution of Pediatric Inflammatory Bowel Disease Unclassified (IBD-U): Incorporated With Serological and Gene Expression Profiles

Prevalence of Inflammatory Bowel Disease Unclassified, as Estimated Using the Revised Porto Criteria, among Korean Pediatric Patients with Inflammatory Bowel Disease

Purpose

Few studies have reported the prevalence of inflammatory bowel disease unclassified (IBDU) among Korean pediatric IBD (PIBD) population. To address this gap, we used two tertiary centers and nationwide population-based healthcare administrative data to estimate the prevalence of Korean pediatric IBDU at the time of diagnosis.

Methods

We identified 136 patients aged 2-17 years with newly diagnosed IBD (94 Crohn's disease [CD] and 42 ulcerative colitis [UC]) from two tertiary centers in Korea between 2005 and 2017. We reclassified these 136 patients using the revised Porto criteria. To estimate the population-based prevalence, we analyzed Korean administrative healthcare data between 2005 and 2016, which revealed 3,650 IBD patients, including 2,538 CD and 1,112 UC. By extrapolating the reclassified results to a population-based dataset, we estimated the prevalence of PIBD subtypes.

Results

Among the 94 CD, the original diagnosis remained unchanged in 93 (98.9%), while the diagnosis of one (1.1%) patient was changed to IBDU. Among the 42 UC, the original diagnosis remained unchanged in 13 (31.0%), while the diagnoses in 11 (26.2%), 17 (40.5%), and one (2.4%) patient changed to atypical UC, IBDU, and CD, respectively. The estimated prevalences of CD, UC, atypical UC, and IBDU in the Korean population were 69.5%, 9.4%, 8.0%, and 13.1%, respectively.

Conclusion

This study is the first in Korea to estimate the prevalence of pediatric IBDU. This prevalence (13.1%) aligns with findings from Western studies. Large-scale prospective multicenter studies on PIBDU are required to examine the clinical features and outcomes of this condition.

Diagnosis change in pediatric inflammatory bowel disease

OBJECTIVES

This study aims to characterize pediatric inflammatory bowel disease (IBD) patients who change diagnosis and describe the characteristics of that change.

METHODS

A retrospective study was conducted on pediatric IBD patients from the ImproveCareNow (ICN) multicenter international cohort from 2007 to January 2019. Primary outcome was change in diagnosis after the first four visits. Other variables included demographics, diagnostics, disease characteristics, and timing.

RESULTS

6.1% of 18,055 patients aged 1-20 years changed diagnosis. Median time between the baseline visit and first diagnosis change was 0.9 years. Change in diagnosis occurred in 257/12,178 (2.1%) patients with Crohn's disease (CD), 347/4758 (7.3%) patients with ulcerative colitis (UC), and 495/1119 (44.2%) patients with IBD-Unclassified (IBD-U). In multivariable analysis, initial diagnosis of IBD-U and longer follow-up times were associated with greater odds of a diagnosis change.

CONCLUSION

IBD-U initial diagnosis and longer follow-up were associated with increased diagnosis change risk. The most common change was reclassification to CD. Disease activity, moderate malnutrition, and presence of EIMs were not associated with change in diagnosis.

Diagnostic utility, disease activity, and disease phenotype correlation of serum ASCA, pANCA, and PR3-ANCA in pediatric inflammatory bowel disease

OBJECTIVE

This study aimed to evaluate the diagnostic utility, disease activity, and phenotypic association of serum anti-Saccharomyces cerevisiae antibody (ASCA), perinuclear anti-neutrophil cytoplasmic antibody (pANCA), PR3-ANCA, and MPO-ANCA in pediatric patients with inflammatory bowel disease (IBD).

METHODS

Pediatric patients diagnosed with IBD were recruited and classified as Crohn's disease (CD), ulcerative colitis (UC), and IBD-unclassified (IBD-U) through full investigation. The Paris classification was used to evaluate disease phenotypes of pediatric CD and UC.

RESULTS

In all, 229 pediatric patients with IBD (CD 147, UC 53, IBD-U 29) were included. The ASCA IgG seropositivity significantly differed among the three groups (CD 75.4%, UC 17.5%, and IBD-U 60.0%; p < 0.001). PR3-ANCA positive rates were the highest in UC (24.0%), followed by IBD-U (17.6%), and none in CD (p = 0.002); pANCA-positive rates were higher in IBD-U (33.6%), followed by UC (28.0%) than in CD (1.4%) (p < 0.001). Regarding disease phenotype, perianal disease revealed higher serum ASCA IgG titers (median 36.7 U/mL in P1 vs. 25.2 U/mL in P0, p = 0.019). Serum ASCA IgG and IgA cutoff values to distinguish CD were 32.7 (U/mL) and 11.9 (U/mL), respectively, with a specificity of 80.0%.

CONCLUSION

Serological biomarkers of ASCA IgG and IgA were effective for differentiating CD in pediatric IBD patients, and serum pANCA and PR3-ANCA, but not MPO-ANCA, were effective in distinguishing UC and IBD-U. Furthermore, measuring serological titers of ASCA IgG and IgA may help differentiate CD and evaluate the disease activity and phenotype of pediatric IBD in practice.

Machine Learning in Antibody Diagnostics for Inflammatory Bowel Disease Subtype Classification

Antibody testing in inflammatory bowel disease (IBD) can add to diagnostic accuracy of the main subtypes Crohn's disease (CD) and ulcerative colitis (UC). Whether modern modeling techniques such as supervised and unsupervised machine learning are of value for finer distinction of subtypes such as IBD-unclassified (IBD-U) is not known. We determined the antibody profile of 100 adult IBD patients from the Swiss IBD cohort study with known subtype (50 CD, 50 UC) as well as of 76 IBD-U patients. We included ASCA IgG and IgA, p-ANCA, MPO- and PR3-ANCA, and xANCA measurements for computing different antibody panels as well as machine learning models. The AUC of an optimized antibody panel was 85% (95%CI, 78-92%) to distinguish CD from UC patients. The antibody profile of IBD-U patients was closely related to UC. No specific antibody profile was predictive for IBD-U nor for re-classification. The panel diagnostic was in favor of UC reclassification prediction with a correct assignment rate of 69.2-73.1% depending on the cut-off applied. Supervised machine learning could not distinguish between CD, UC, and IBD-U. More so, unsupervised machine learning suggested only two distinct clusters as a likely number of IBD subtypes. Antibodies in IBD are supportive in confirming clinical determined subtypes CD and UC but have limited capacity to predict IBD-U and reclassification during follow-up. In terms of antibody profiles, IBD-U is not a distinct subtype of IBD.

Deciphering the role of autophagy in the immunopathogenesis of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a typical immune-mediated chronic inflammatory disorder. Following the industrialization and changes in lifestyle, the incidence of IBD in the world is rising, which makes health concerns and heavy burdens all over the world. However, the pathogenesis of IBD remains unclear, and the current understanding of the pathogenesis involves dysregulation of mucosal immunity, gut microbiome dysbiosis, and gut barrier defect based on genetic susceptibility and environmental triggers. In recent years, autophagy has emerged as a key mechanism in IBD development and progression because Genome-Wide Association Study revealed the complex interactions of autophagy in IBD, especially immunopathogenesis. Besides, autophagy markers are also suggested to be potential biomarkers and target treatment in IBD. This review summarizes the autophagy-related genes regulating immune response in IBD. Furthermore, we explore the evolving evidence that autophagy interacts with intestinal epithelial and immune cells to contribute to the inflammatory changes in IBD. Finally, we discuss how novel discovery could further advance our understanding of the role of autophagy and inform novel therapeutic strategies in IBD.

The Therapeutic Role of Short-Chain Fatty Acids Mediated Very Low-Calorie Ketogenic Diet-Gut Microbiota Relationships in Paediatric Inflammatory Bowel Diseases

The very low-calorie ketogenic diet (VLCKD) has been recognized as a promising dietary regimen for the treatment of several diseases. Short-chain fatty acids (SCFAs) produced by anaerobic bacterial fermentation of indigestible dietary fibre in the gut have potential value for their underlying epigenetic role in the treatment of obesity and asthma-related inflammation through mediating the relationships between VLCKD and the infant gut microbiota. However, it is still unclear how VLCKD might influence gut microbiota composition in children, and how SCFAs could play a role in the treatment of inflammatory bowel disease (IBD). To overcome this knowledge gap, this review aims to investigate the role of SCFAs as key epigenetic metabolites that mediate VLCKD-gut microbiota relationships in children, and their therapeutic potential in IBD.

SYSTEMATIC REVIEW AND META - ANALYSIS OF THE FREQUENCY AND RE-CLASSIFICATION TRENDS OF PEDIATRIC INFLAMMATORY BOWEL DISEASE - UNCLASSIFIED

BACKGROUND

The term inflammatory bowel disease-unclassified (IBDU) is used when an individual has chronic colitis but cannot be sub-typed into ulcerative colitis (UC) or Crohn's disease (CD) on the basis of the clinical, endoscopic, imaging and histopathological features. On follow-up a proportion of patients with IBDU are re-classified as CD or UC. There has been considerable variability in the frequency and reclassification rates of pediatric IBDU in published literature.

METHODS

PubMed and Scopus and were searched for publications related to Pediatric Inflammatory Bowel Disease (PIBD) published between Jan,2014 and July,2021. Two reviewers independently searched and selected studies reporting the frequency of IBDU and/or their re-classification. The pooled prevalence was expressed as proportion and 95%CI. Meta-analysis was performed using the inverse variance heterogeneity model.

RESULTS

A total of 2750 studies were identified through a systematic search of which 27 studies were included in this systematic review. The overall pooled frequency of IBDU (n=16064) was found to be 7.1% (95%CI 5.8-8.5%). There was no variation in IBDU frequency by geographical location. Seven studies (n=5880) were included in the IBDU re-classification analysis. Overall, 50% (95%CI 41-60%) children with IBDU were re-classified on follow-up. Amongst these 32.7% (95% 21-44%) were re-classified to UC and 17% (95%CI 12-22%) were re-classified to CD.

CONCLUSION

IBDU comprises 7.1% of PIBD at initial diagnosis. Half of these children are re-classified into UC or CD on follow-up with a higher likelihood of re-classification to UC as compared to CD.

Appraisal of the PIBD-classes Criteria: A Multicentre Validation

INTRODUCTION

The PIBD-classes criteria were developed to standardise the classification of children with inflammatory bowel disease [IBD], from Crohn's disease [CD], through IBD-unclassified [IBD-U], to typical ulcerative colitis [UC]. We aimed to further validate the criteria and to explore possible modifications.

METHODS

This was a multicentre retrospective cohort study of children diagnosed with IBD with at least 1 year of follow-up. Clinical, radiological, endoscopic, and histological data were recorded at diagnosis and latest follow-up, as well as the 23 items of the PIBD-classes criteria. The PIBD-classes criteria were assessed for redundant items, and a simplified algorithm was proposed and validated on the original derivation cohort from which the PIBD-classes algorithm was derived.

RESULTS

Of the 184 included children [age at diagnosis 13 ± 3 years, 55% males], 122 [66%] were diagnosed by the physician with CD, 17 [9%] with IBD-U, and 45 [25%] with UC. There was high agreement between physician-assigned and PIBD-classes generated diagnosis for CD [93%; eight patients moved to IBD-U] and for UC [84%; six moved to IBD-U and one to CD]. A simplified version of the algorithm with only 19 items is suggested, with comparable performance to the original algorithm [81% sensitivity and 81% specificity vs 78% and 83% for UC; and 79% and 95% vs 80% and 95% for CD, respectively].

CONCLUSIONS

The PIBD-classes algorithm is a useful tool to facilitate standardised objective classification of IBD subtypes in children. A modified version of the PIBD-classes maintains accuracy of classification with a simplified algorithm.

Patterns of mucosal inflammation in pediatric inflammatory bowel disease: striking overexpression of IL-17A in children with ulcerative colitis

BACKGROUND

Aberrant immune responses play a key role in the pathogenesis of inflammatory bowel disease (IBD). Most studies conducted to delineate the underlying molecular mechanisms focus on adults; an understanding of these mechanisms in children remains to be determined. Here, cytokines and transcription factors produced by immune cells within the intestinal mucosa of pediatric patients stricken with ulcerative colitis (UC) and Crohn's disease (CD) are characterized; potential diagnostic and therapeutic targets are identified.

METHODS

Fifty-two pediatric IBD and non-IBD patients were enrolled in the study. Specimens were taken during ileocolonoscopy. Expression of 16 genes that encode cytokines or transcription molecules was determined by quantitative polymerase chain reaction. Clinical data were collected via retrospective chart review.

RESULTS

Overexpression of interleukin-17A (IL-17A) was evident in children with UC compared to both non-IBD and CD patients. IL-22 was strongly increased in UC patients only. Typical proinflammatory and immunoregulatory cytokines were pronounced in IBD patients, although to a lower extent in the latter case. Clustered gene expression enabled differentiation between UC and non-IBD patients.

CONCLUSION

Our findings highlight the crucial involvement of IL-17A immunity in the early course of IBD, particularly UC, and the potential value of gene panels in diagnosing pediatric IBD.

Differentiation of Colonic Inflammatory Bowel Disease: Re-examination of Paediatric Inflammatory Bowel Disease Classes Algorithm With Resected Colon As the Criterion Standard

OBJECTIVES

Differentiation of Crohn disease (CD) from ulcerative colitis (UC) is challenging when inflammation is predominantly colonic. The paediatric inflammatory bowel disease (PIBD) classes algorithm was developed to bring consistency to labelling, but used physician-assigned diagnosis as the criterion standard. We aimed to reassess the PIBD classes using pathology of subsequently resected colon as the criterion standard.

METHOD

Single-centre study of patients diagnosed with colonic IBD between 2002 and 2017 and subsequently treated with colectomy. Baseline pretreatment data were reviewed and the PIBD classes algorithm was independently applied by 2 reviewers to assign a label of UC/IBD-unclassified (IBD-U)/colonic-CD. Concordance between the algorithm-based, precolectomy clinical, and pathologic examination of resected colon diagnosis were assessed. Changes in diagnosis during postcolectomy follow-up were recorded.

RESULTS

Sixty-two children underwent colectomy for medically refractory colonic IBD. Diagnosis based on pathologic review of resected colon CD:4;UC:56;IBDU:2. The clinical, PIBD classes algorithm, and colectomy diagnoses were concordant in 51 of 62 patients (81%, Fleiss kappa 0.48). Precolectomy clinical diagnosis was concordant with colectomy diagnosis in 58 of 62 patients (94%, weighted-kappa 0.65). The PIBD classes label was concordant with colectomy diagnosis in 51 of 62 patients (82%, weighted-kappa 0.38); resected colon pathology was typical of UC in 6 patients with PIBD classes label of IBD-U based on single class 2 feature and in 3 with PIBD classes label of CD based on single class 1 feature.

CONCLUSIONS

Concordance of PIBD classes algorithm diagnosis applied before colectomy with a diagnostic label based on pathologic examination of a subsequently resected colon is only fair. Caution is needed in stringent application of colonic CD and IBD-U labels based on presence of single feature.

An Overview of Inflammatory Bowel Disease Unclassified in Children

Background

The inflammatory bowel diseases cover a diverse range of conditions generally grouped into Crohn's disease (CD) or ulcerative colitis (UC) based on clinical, laboratory, radiological, endoscopic, and histological criteria. However, inflammatory bowel disease unclassified (IBDU) is used when there are clinical and endoscopic signs of chronic colitis without specific features of UC or CD but features of both. Conjecture exists regarding IBDU, especially in children, as to whether it represents a unique childhood phenotype or whether it reflects the difficulties in assigning an IBD subtype at an early age.

Summary

This review examines the current understanding of pediatric IBDU and assesses the evidence supporting IBDU as a distinctive disease entity on the spectrum of inflammatory bowel disease.

Key Messages

Pediatric-onset IBDU is more common than adult-onset IBDU. Therefore, an understanding of IBDU in this age group assumes more importance. However, there remains a paucity of information and a lack of exclusive longitudinal studies on pediatric IBDU. Subsequently there is significant disparity in the reported prevalence, clinical course, reclassification trends, and treatment responses around pediatric IBDU. Therefore, it remains challenging to chart the natural history of pediatric IBDU and consequently form an accurate understanding of where pediatric IBDU sits on the spectrum of disease.

Pediatric inflammatory bowel disease: continuous lessons for adult inflammatory bowel disease

PURPOSE OF REVIEW

Prospective and inception inflammatory bowel disease (IBD) cohorts offer excellent opportunities to develop risk stratification strategies, use relevant tissue to explore the biology of IBD progression, and study the natural history of IBD in the era of biological therapy. Adult IBD care can learn important lessons from recent pediatric IBD studies.

RECENT FINDINGS

A recent multicenter inception cohort of pediatric IBD patients examining genetic, serologic, and microbiome data at diagnosis has been able to create a model for prediction of disease complications, describe compositional changes in gut microbiota associated with disease severity, identify markers of intestinal fibrosis, and confirm how important early life environmental exposures affect disease severity and phenotype. Analysis of gene and protein expression in mucosal samples has been shown to offer both diagnostic information about differentiation of ulcerative colitis (UC) vs. crohn's disease as well as implications for treatment efficacy. Important developments in treatment of growth failure with antitumor necrosis factor therapy, the effect of oral medication noncompliance, and dietary IBD therapy are outlined.

SUMMARY

Pediatric IBD research has been focusing on better phenotyping at diagnosis, and development of molecular signatures of future disease behavior by using relevant intestinal tissue rather than blood. This has moved IBD from being a heterogeneous group of diseases with an unknown disease course to a better-defined condition in which patients are accurately risk stratified and treated based on individualized distinct biological and clinical information.