Diagnostic utility of serological biomarkers in patients with Crohn's disease: A case-control study

Diagnostic Procedures for Inflammatory Bowel Disease: Laboratory, Endoscopy, Pathology, Imaging, and Beyond

Diagnosing inflammatory bowel disease (IBD) can often be challenging, and differentiating between Crohn's disease and ulcerative colitis can be particularly difficult. Diagnostic procedures for IBD include laboratory tests, endoscopy, pathological tests, and imaging tests. Serological and stool tests can be easily performed in an outpatient setting and provide critical diagnostic clues. Although endoscopy is an invasive procedure, it offers essential diagnostic information and allows for tissue biopsy and therapeutic procedures. Video capsule endoscopy and device-assisted enteroscopy are endoscopic procedures used to evaluate the small bowel. In addition to endoscopy, magnetic resonance imaging, computed tomography, and ultrasound (US) are valuable tools for small bowel assessment. Among these, US is noninvasive and easily utilized, making its use highly practical in daily clinical practice. Endoscopic biopsy aids in the diagnosis of IBD and is crucial for assessing the histological activity of the disease, facilitating a thorough evaluation of disease remission, and aiding in the development of treatment strategies. Recent advances in artificial intelligence hold promise for enhancing various aspects of IBD management, including diagnosis, monitoring, and precision medicine. This review compiles current procedures and promising future tools for the diagnosis of IBD, providing comprehensive insights.

From ASCA breakthrough in Crohn's disease and Candida albicans research to thirty years of investigations about their meaning in human health

Anti-Saccharomyces cerevisiae antibodies (ASCA) are human antibodies that can be detected using an enzyme-linked immunosorbent assay involving a mannose polymer (mannan) extracted from the cell wall of the yeast S. cerevisiae. The ASCA test was developed in 1993 with the aim of differentiating the serological response in two forms of inflammatory bowel disease (IBD), Crohn's disease and ulcerative colitis. The test, which is based on the detection of anti-oligomannosidic antibodies, has been extensively performed worldwide and there have been hundreds of publications on ASCA. The earlier studies concerned the initial diagnostic indications of ASCA and investigations then extended to many human diseases, generally in association with studies on intestinal microorganisms and the interaction of the micro-mycobiome with the immune system. The more information accumulates, the more the mystery of the meaning of ASCA deepens. Many fundamental questions remain unanswered. These questions concern the heterogeneity of ASCA, the mechanisms of their generation and persistence, the existence of self-antigens, and the relationship between ASCA and inflammation and autoimmunity. This review aims to discuss the gray areas concerning the origin of ASCA from an analysis of the literature. Structured around glycobiology and the mannosylated antigens of S. cerevisiae and Candida albicans, this review will address these questions and will try to clarify some lines of thought. The importance of the questions relating to the pathophysiological significance of ASCA goes far beyond IBD, even though these diseases remain the preferred models for their understanding.

The Correlation between New Serological Markers and Disease Phenotype and Activation in Inflammatory Bowel Disease

Background: The aim of the study is to assess the correlation between a new antibody panel that is developed against glycans on Crohn's disease (CD) and ulcerative colitis (UC) differentiative diagnosis and disease properties. Methods: In the study, 137 CD and 122 UC patients and 90 controls were included. Anti-saccharomyces cerevisiae IgG (ASCA), anti-laminaribioside IgG (ALCA), anti-chitobioside IgA (ACCA), and anti-mannobioside IgG (AMCA) were tested in serum. Results: While at least 1 of the other 3 serological markers was positive in 89% of ASCA-positive patients, at least 1 of the other 3 serological markers was positive in 77% of ASCA-negative patients. Positivity ratio for a single anticarbohydrate was ALCA 18 (22%), ACCA 5 (12%), and AMCA 16 (23%). A significant correlation was found between ASCA positivity (P<0.001) in operated patients and between ASCA, ALCA, and ACCA positivity (P<0.05) in patients with stricturing and fistulizing CD. According to the ROC analysis, ASCA was found to have the highest area under the curve (0.70-0.82) (correlation coefficient interval 95%). A significant correlation was found between ASCA, ALCA, and ACCA positivity and high serum antibody levels and disease activation (P<0.05). Conclusion: ASCA, ALCA, and ACCA were found to be correlated with the disease complication and activation in CD. ASCA and ALCA were determined as the best markers in the differentiation between CD and UC.

Identification of Prevotella Oralis as a possible target antigen in children with Enthesitis related arthritis

OBJECTIVES

Patients with Crohn's disease often produce antibodies against flagellated intestinal bacteria. There are mixed data as to whether such antibodies are present in patients with spondyloarthritis. Our objectives were to evaluate for the presence of antibodies against intestinal organisms in children with enthesitis related arthritis (ERA).

METHODS

Children with ERA and healthy controls were recruited at three sites. Sera were plated on a nitrocellulose array and incubated with labelled antibodies to human IgA and IgG.

RESULTS

At UAB, patients and controls had similar antibody levels against the majority of the bacteria selected, with the exception of increased IgA antibodies among ERA patients against Prevotella oralis (1231 [IQR 750, 2566] versus 706 [IQR 428, 1106], p = .007.) These findings were partially validated at a second but not at a third site.

CONCLUSIONS

ERA patients may produce increased IgA antibodies against P. oralis. The possible significance of this finding bears further exploration.

First-degree Relatives of Celiac Disease Patients Have Increased Seroreactivity to Serum Microbial Markers

Risk of celiac disease (CD) is increased in relatives of CD patients due to genetic and possible environmental factors. We recently reported increased seropositivity to anti-Saccharomyces cerevisiae (ASCA), Pseudomonas fluorescens-associated sequence (anti-I2) and Bacteroides caccae TonB-linked outer membrane protein (anti-OmpW) antibodies in CD. We hypothesized these markers also to be overrepresented in relatives. Seropositivity and levels of ASCA, anti-I2 and anti-OmpW were compared between 463 first-degree relatives, 58 untreated and 55 treated CD patients, and 80 controls. CD-associated human leukocyte antigen (HLA)-haplotypes and transglutaminase (tTGab) and endomysium (EmA) antibodies were determined. One or more of the microbial antibodies was present in 75% of relatives, 97% of untreated and 87% of treated CD patients and 44% of the controls. The relatives had higher median ASCA IgA (9.13 vs. 4.50 U/mL, p < 0.001), ASCA IgG (8.91 vs. 5.75 U/mL, p < 0.001) and anti-I2 (absorbance 0.74 vs. 0.32, p < 0.001) levels than controls. There was a weak, positive correlation between tTGab and ASCA (r = 0.31, p < 0.001). Seropositivity was not significantly associated with HLA. To conclude, seropositivity to microbial markers was more common and ASCA and anti-I2 levels higher in relatives of CD patients than controls. These findings were not associated with HLA, suggesting the role of other genetic and environmental factors.

Association Between Serological Markers and Crohn's Disease Activity

Background

The aim was to study the association between six serological markers and Crohn’s disease (CD) activity at an inflammatory bowel disease (IBD) referral center.

Methods

We designed a retrospective cohort study using adults (> 18 years) with CD followed for at least 1 year at University of Alabama at Birmingham. Baseline serological markers ASCA-IgA, ASCA-IgG, anti-OmpC IgA, anti-CBir1 IgG, anti-A4Fla2 IgG and anti-FlaX IgG were drawn at initial visit. Poisson regression was used to assess the longitudinal relationship between these markers drawn at baseline and rate of active clinical disease during follow-up.

Results

Each marker, from 135 patients, was categorized into high vs. low. A Poisson regression model adjusted for age, gender, race, duration of disease, obesity, proton pump inhibitor; steroid and thiopurine use, and disease location demonstrated that CD patients with high anti-CBir1 IgG at baseline were approximately twice more likely to have active clinical disease (incidence rate ratio (IRR) 2.06, 95% confidence interval (CI) 1.28 - 3.33, P = 0.0032). The unadjusted Poisson regression model for A4Fla2 IgG antibody level did suggest that a high A4Fla2 IgG at baseline was associated with a higher likelihood of active CD (IRR 1.64, 95% CI 1.07, 2.53, P = 0.0238) which however, upon adjustment based on effect size, was not significant. The other four antibodies did not appear to predict clinical course.

Conclusions

High levels of anti-CBir1 IgG appear to be associated with a greater likelihood of active CD. Whether routine baseline testing for anti-CBir1 IgG to predict a more active clinical course is warranted needs more research.