Increased antibody response to microbial antigens in patients with Crohn's disease and their unaffected first-degree relatives

Biomarkers in IBD: What to Utilize for the Diagnosis?

The role of biomarkers in the diagnosis of inflammatory bowel disease is not fully characterized. C-reactive protein has a short half-life and elevates quickly after the onset of an inflammatory process; the performance is better in Crohn's disease than in ulcerative colitis. Erythrocyte sedimentation rate is easy to determine, widely available, and cheap, but the long half-life, the influence of age, anemia, smoking, and drugs limit its usefulness. Fecal markers have good specificity, but suboptimal accuracy. Microbial antibodies and novel immunological markers show promise but need further evidence before entering clinical practice. Proteomic methods could represent the dawn of a new era of stool protein/peptide biomarker panels able to select patients at risk of inflammatory bowel disease.

Recent Advances and Potential Multi-Omics Approaches in the Early Phases of Inflammatory Bowel Disease

Inflammatory bowel disease leads to debilitating gastrointestinal symptoms and reduced quality of life, resulting in a significant burden on healthcare utilization and costs. Despite substantial advancements in diagnosis and treatment, there may still be considerable delays in diagnosing some patients. To reduce disease progression before the full disease spectrum appears and improve prognostic outcomes, several strategies have concentrated on early intervention and prevention. Recent evidence shows that initial immune response changes and endoscopic lesions may exist for years before diagnosis, implying the existence of a preclinical phase of inflammatory bowel disease comparable to findings in other immune-mediated disorders. In this review, we highlight the most relevant findings regarding preclinical inflammatory bowel disease and the prospective role of novel omics techniques in this field.

Prebiotic fructans have greater impact on luminal microbiology and CD3+ T cells in healthy siblings than patients with Crohn's disease: A pilot study investigating the potential for primary prevention of inflammatory bowel disease

BACKGROUND & AIMS

Siblings of people with Crohn's disease (CD) share aspects of the disease phenotype (raised faecal calprotectin, altered microbiota), which are markers of risk for their own development of CD. The aim was to determine whether supplementation with prebiotic oligofructose/inulin induces a prebiotic response and impacts the risk phenotype in CD patients and siblings.

METHODS

Patients with inactive CD (n = 19, CD activity index <150) and 12 of their unaffected siblings (with calprotectin >50 μg/g) ingested oligofructose/inulin (15 g/day) for three weeks. Faecal microbiota (qPCR), intestinal permeability (lactulose-rhamnose test), blood T cells (flow-cytometry) and calprotectin (ELISA) were measured at baseline and follow-up.

RESULTS

Following oligofructose/inulin, calprotectin did not significantly change in patients (baseline mean 537 SD 535 μg/g; follow-up mean 974 SD 1318 μg/g, p = 0.08) or siblings (baseline mean 73 SD 90 μg/g: follow up mean 58 SD 72 μg/g, p = 0.62). Faecal Bifidobacteria and Bifidobacterium longum increased in patients and siblings; Bifidobacterium adolescentis and Roseburia spp. increased only in siblings. Compared with patients, siblings had a greater magnitude change in Bifidobacteria (+14.6% vs +0.4%, p = 0.028), B. adolescentis (+1.1% vs 0.0% p = 0.006) and Roseburia spp. (+1.5% vs -0.1% p = 0.004). Intestinal permeability decreased significantly in patients after oligofructose/inulin to a level that was similar to siblings. Blood T cell abundance reduced in siblings but not patients following oligofructose/inulin.

CONCLUSIONS

Oligofructose/inulin supplementation did not significantly impact calprotectin, but the prebiotic effect was more marked in healthy siblings compared with patients with inactive CD and was associated with alterations in other CD risk markers. Future research should focus on dietary intervention, including with prebiotics, in the primary prevention of CD.

Inflammatory Bowel Disease Serological Immune Markers Anti-Saccharomyces cerevisiae Mannan Antibodies and Outer Membrane Porin C are Potential Biomarkers for Hirschsprung-associated Enterocolitis

OBJECTIVE

Hirschsprung-associated enterocolitis (HAEC) is the most frequent complication in Hirschsprung disease (HSCR) patients. Currently HAEC is diagnosed clinically, leaving uncertainty in the diagnosis thereby potentially leading to over- or undertreatment of patients. The aim of this study was to identify immune biomarkers to aid in the diagnosis of HAEC.

METHODS

From 2012 to 2017, 43 children with HSCR enrolled in a multicenter study, underwent retrospective evaluation of their medical records, and questionnaire-directed parent interviews. HAEC status was determined using HAEC score with cutoff ≥4. Plasma was collected and analyzed by ELISA for the inflammatory bowel disease-associated antibodies: anti-Saccharomyces cerevisiae mannan antibodies (ASCA), outer membrane porin C (OmpC), CBir1, antineutrophil cytoplasmic antibodies. Data were analyzed using t test, univariate, multivariable, and binomial regression models.

RESULTS

Eighteen patients had at least 1 episode of HAEC, 25 had no history of HAEC. The HAEC and NO HAEC groups had similar median ages (3 years) and family histories of HSCR. The HAEC group showed markedly elevated ASCA IgA and OmpC antibody levels compared with the NO HAEC group, whereas CBir1 and antineutrophil cytoplasmic antibodies were similar between the groups. Both univariate and multivariable analysis revealed higher OmpC antibody levels associated with HAEC (odds ratio 1.39, confidence interval 1-1.92, P = 0.048), whereas univariate analysis identified a trend toward elevated IgA and immunoglobulin G ASCA levels with HAEC.

CONCLUSIONS

We identified elevated OmpC and ASCA serum antibody levels in HAEC patients, and that increased OmpC antibody levels correlated with HAEC occurrence, suggesting HAEC and Crohn disease share gut microbial-host immune responses. These antibodies may serve as potential biomarkers for HAEC, although prospective study with larger sample size is needed.

The distinct features of microbial 'dysbiosis' of Crohn's disease do not occur to the same extent in their unaffected, genetically-linked kindred

Background/Aims

Studying the gut microbiota in unaffected relatives of people with Crohn’s disease (CD) may advance our understanding of the role of bacteria in disease aetiology.

Methods

Faecal microbiota composition (16S rRNA gene sequencing), genetic functional capacity (shotgun metagenomics) and faecal short chain fatty acids (SCFA) were compared in unaffected adult relatives of CD children (CDR, n = 17) and adult healthy controls, unrelated to CD patients (HUC, n = 14). The microbiota characteristics of 19 CD children were used as a benchmark of CD ‘dysbiosis’.

Results

The CDR microbiota was less diverse (p = 0.044) than that of the HUC group. Local contribution of β-diversity analysis showed no difference in community structure between the CDR and HUC groups. Twenty one of 1,243 (1.8%) operational taxonomic units discriminated CDR from HUC. The metagenomic functional capacity (p = 0.207) and SCFA concentration or pattern were similar between CDR and HUC (p>0.05 for all SCFA). None of the KEGG metabolic pathways were different between these two groups. Both of these groups (HUC and CDR) had a higher microbiota α-diversity (CDR, p = 0.026 and HUC, p<0.001) with a community structure (β-diversity) distinct from that of children with CD.

Conclusions

While some alterations were observed, a distinct microbial ‘dysbiosis’, characteristic of CD patients, was not observed in their unaffected, genetically linked kindred.

Unique β-Glucuronidase Locus in Gut Microbiomes of Crohn's Disease Patients and Unaffected First-Degree Relatives

Crohn's disease, an incurable chronic inflammatory bowel disease, has been attributed to both genetic predisposition and environmental factors. A dysbiosis of the gut microbiota, observed in numerous patients but also in at least one hundred unaffected first-degree relatives, was proposed to have a causal role. Gut microbiota β-D-glucuronidases (EC 3.2.1.33) hydrolyse β-D-glucuronate from glucuronidated compounds. They include a GUS group, that is homologous to the Escherichia coli GusA, and a BG group, that is homologous to metagenomically identified H11G11 BG and has unidentified natural substrates. H11G11 BG is part of the functional core of the human gut microbiota whereas GusA, known to regenerate various toxic products, is variably found in human subjects. We investigated potential risk markers for Crohn's disease using DNA-sequence-based exploration of the β-D-glucuronidase loci (GUS or Firmicute H11G11-BG and the respective co-encoded glucuronide transporters). Crohn's disease-related microbiomes revealed a higher frequency of a C7D2 glucuronide transporter (12/13) compared to unrelated healthy subjects (8/32). This transporter was in synteny with the potential harmful GUS β-D-glucuronidase as only observed in a Eubacterium eligens plasmid. A conserved NH2-terminal sequence in the transporter (FGDFGND motif) was found in 83% of the disease-related subjects and only in 12% of controls. We propose a microbiota-pathology hypothesis in which the presence of this unique β-glucuronidase locus may contribute to an increase risk for Crohn's disease.

Host-microbiome interaction in Crohn’s disease: A familiar or familial issue?

An impaired interaction between the gut and the intestinal microbiome is likely to be the key element in the pathogenesis of Crohn’s disease (CD). Family studies have provided invaluable information on CD pathogenesis and on its etiology. Relatives share the same genetic risk of developing the disease as affected subjects. Relatives also exhibit similar features relating to their host-microbiome interaction, namely genetic variants in loci involved in detecting bacteria, a greater sero-reactivity to microbial components, and an impaired intestinal permeability. The burden of environmental factors such as cigarette smoking and dysbiosis also seems to be particularly relevant in these genetically predisposed subjects. Diet is emerging as an important factor and could account for the changing epidemiology of CD in recent years. Despite the pivotal role of genetics in the disease’s pathogenesis (especially in familial CD), screening tests in healthy relatives cannot be recommended.

Overcoming difficulty in diagnosis and differential diagnosis of Crohn's disease: the potential role of serological and genetic tests

Crohn's disease (CD) represents a heterogeneous group of chronic inflammatory disorders with various phenotypes. Establishing a definite diagnosis of CD should be based upon a combined assessment of clinical, endoscopic, radiological and pathological features. Although segmental disease distribution, transmural inflammation and non-caseating epithelioid granulomas have been considered as a 'hallmarks' for CD, clear diagnosis of CD in some patients has been challenging, due to overlapping endoscopic, radiographic and histologic features with other inflammatory bowel disease-like conditions. Laboratory markers (serological and genetic tests) may provide additional clues for the diagnosis and differential diagnosis of CD. This review focuses on the application of the currently available serological and genomic markers and in diagnosis and differential diagnosis of CD.

Systematic review: new serological markers (anti-glycan, anti-GP2, anti-GM-CSF Ab) in the prediction of IBD patient outcomes

Traditionally, IBD diagnosis is based on clinical, radiological, endoscopic, and histological criteria. Biomarkers are needed in cases of uncertain diagnosis, or to predict disease course and therapeutic response. No guideline recommends the detection of antibodies (including ASCA and ANCA) for diagnosis or prognosis of IBD to date. However, many recent data suggest the potential role of new serological markers (anti-glycan (ACCA, ALCA, AMCA, anti-L and anti-C), anti-GP2 and anti-GM-CSF Ab). This review focuses on clinical utility of these new serological markers in diagnosis, prognosis and therapeutic monitoring of IBD. Literature review of anti-glycan, anti-GP2 and anti-GM-CSF Ab and their impact on diagnosis, prognosis and prediction of therapeutic response was performed in PubMed/MEDLINE up to June 2014. Anti-glycan, anti-GP2 and anti-GM-CSF Ab are especially associated with CD and seem to be correlated with complicated disease phenotypes even if results differ between studies. Although anti-glycan Ab and anti-GP2 Ab have low sensitivity in diagnosis of IBD, they could identify a small number of CD patients not detected by other tests such as ASCA. Anti-glycan Abs are associated with a progression to a more severe disease course and a higher risk for IBD-related surgery. Anti-GP2 Ab could particularly contribute to better stratify cases of pouchitis. Anti-GM-CSF Ab seems to be correlated with disease activity and could help predict relapses. These new promising biomarkers could particularly be useful in stratification of patients according to disease phenotype and risk of complications. They could be a valuable aid in prediction of disease course and therapeutic response but more prospective studies are needed.