Antibody to selected strains of Saccharomyces cerevisiae (baker's and brewer's yeast) and Candida albicans in Crohn's disease

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.

Colonic mucosal associated invariant T cells in Crohn's disease have a diverse and non-public T cell receptor beta chain repertoire

OBJECTIVES

Mucosal-Associated Invariant T (MAIT) cells are T cells with a semi-invariant T cell receptor (TCR), recognizing riboflavin precursors presented by a non-polymorphic MR1 molecule. As these precursors are produced by the gut microbiome, we characterized the frequency, phenotype and clonality of MAIT cells in human colons with and without Crohn's disease (CD).

METHODS

The transcriptome of MAIT cells sorted from blood and intestinal lamina propria cells from colectomy recipients were compared with other CD8+ T cells. Colon biopsies from an additional ten CD patients and ten healthy controls (HC) were analyzed by flow cytometry. TCR genes were sequenced from individual MAIT cells from these biopsies and compared with those of MAIT cells from autologous blood.

RESULTS

MAIT cells in the blood and colon showed a transcriptome distinct from other CD8 T cells, with more expression of the IL-23 receptor. MAIT cells were enriched in the colons of CD patients, with less NKG2D in inflamed versus uninflamed segments. Regardless of disease, most MAIT cells expressed integrin α4β7 in the colon but not in the blood, where they were enriched for α4β7 expression. TCR sequencing revealed heterogeneity in the colon and blood, with few public sequences associated with cohorts.

CONCLUSION

MAIT cells are enriched in the colons of CD patients and disproportionately express molecules (IL-23R, integrin α4β7) targeted by CD therapeutics, to suggest a pathogenic role for them in CD. Public TCR sequences were neither common nor sufficiently restricted to a cohort to suggest protective or pathogenic antigen-specificities.

Commensal fungi in intestinal health and disease

The microbiota is known to influence several facets of mammalian development, digestion and disease. Most studies of the microbiota have focused on the bacterial component, but the importance of commensal fungi in health and disease is becoming increasingly clear. Although fungi account for a smaller proportion of the microbiota than bacteria by number, they are much larger and therefore account for a substantial proportion of the biomass. Moreover, as fungi are eukaryotes, their metabolic pathways are complex and unique. In this Review, we discuss the evidence for involvement of specific members of the mycobiota in intestinal diseases, including inflammatory bowel disease, colorectal cancer and pancreatic cancer. We also highlight the importance of fungal interactions with intestinal bacteria and with the immune system. Although most studies of commensal fungi have focused on their role in disease, we also consider the beneficial effects of fungal colonies in the gut. The evidence highlights potential opportunities to target fungi and their interactions for therapeutic purposes.

Selection of cross-reactive T cells by commensal and food-derived yeasts drives cytotoxic TH1 cell responses in Crohn's disease

Aberrant CD4+ T cell reactivity against intestinal microorganisms is considered to drive mucosal inflammation in inflammatory bowel diseases. The disease-relevant microbial species and the corresponding microorganism-specific, pathogenic T cell phenotypes remain largely unknown. In the present study, we identified common gut commensal and food-derived yeasts, as direct activators of altered CD4+ T cell reactions in patients with Crohn's disease (CD). Yeast-responsive CD4+ T cells in CD display a cytotoxic T helper cell (TH1 cell) phenotype and show selective expansion of T cell clones that are highly cross-reactive to several commensal, as well as food-derived, fungal species. This indicates cross-reactive T cell selection by repeated encounter with conserved fungal antigens in the context of chronic intestinal disease. Our results highlighted a role of yeasts as drivers of aberrant CD4+ T cell reactivity in patients with CD and suggest that both gut-resident fungal commensals and daily dietary intake of yeasts might contribute to chronic activation of inflammatory CD4+ T cell responses in patients with CD.

Specific fungi associated with response to capsulized fecal microbiota transplantation in patients with active ulcerative colitis

Objective

Fecal microbiota transplantation (FMT) is a novel microbial treatment for patients with ulcerative colitis (UC). In this study, we performed a clinical trial of capsulized FMT in UC patients to determine the association between the gut fungal community and capsulized FMT outcomes.

Design

This study recruited patients with active UC (N = 22) and healthy individuals (donor, N = 9) according to the criteria. The patients received capsulized FMT three times a week. Patient stool samples were collected before (week 0) and after FMT follow-up visits at weeks 1, 4, and 12. Fungal communities were analysed using shotgun metagenomic sequencing.

Results

According to metagenomic analysis, fungal community evenness index was greater in samples collected from patients, and the overall fungal community was clustered among the samples collected from donors. The dominant fungi in fecal samples collected from donors and patients were Ascomycota and Basidiomycota. However, capsulized FMT ameliorated microbial fungal diversity and altered fungal composition, based on metagenomic analysis of fecal samples collected before and during follow-up visits after capsulized FMT. Fungal diversity decreased in samples collected from patients who achieved remission after capsulized FMT, similar to samples collected from donors. Patients achieving remission after capsulized FMT had specific enrichment of Kazachstania naganishii, Pyricularia grisea, Lachancea thermotolerans, and Schizosaccharomyces pombe compared with patients who did not achieve remission. In addition, the relative abundance of P. grisea was higher in remission fecal samples during the follow-up visit. Meanwhile, decreased levels of pathobionts, such as Candida and Debaryomyces hansenii, were associated with remission in patients receiving capsulized FMT.

Conclusion

In the metagenomic analysis of fecal samples from donors and patients with UC receiving capsulized FMT, shifts in gut fungal diversity and composition were associated with capsulized FMT and validated in patients with active UC. We also identified the specific fungi associated with the induction of remission. ClinicalTrails.gov (NCT03426683).

Newly Diagnosed Crohn's Disease Patients in India and Israel Display Distinct Presentations and Serological Markers: Insights from Prospective Cohorts

Background: Crohn’s disease (CD) incidence is rising in India. However, features of newly diagnosed patients with CD in this population are largely unknown. The Indo-Israeli IBD GastroEnterology paRtnership (TiiiGER) aimed to investigate differences in presentation among patients with newly diagnosed CD in India and Israel, and to explore phenotype−serotype correlations. Methods: A prospective observational cohort study of consecutive adults (>18 years) conducted in two large referral centers in India and Israel (2014−2018). Clinical data, an antiglycan serological panel, and 20 CD-associated genetic variants were analyzed. Outcomes: complicated phenotype at diagnosis and early complicated course (hospitalizations/surgeries) within 2 years of diagnosis. Results: We included 260 patients (104, Indian (65.4%, male; age, 37.8); 156 Israeli (49.4%, male; 31.8, age)). Median lag time from symptoms onset to diagnosis was 10.5 (IQR 3−38) vs. 3 (IQR 1−8) months in Indian vs. Israeli patients (p < 0.001). Complicated phenotype at diagnosis was observed in 48% of Indian and 30% of Israeli patients (p = 0.003). Complicated phenotype was associated with higher anti-Saccharomyces cerevisiae antibody (ASCA) seropositivity rate among Israeli patients (p < 0.001), but not among Indian patients. Antiglycan serology did not correlate with the tested genetic variants. Early complicated course occurred in 28 (18%) Israeli and 13 (12.5%) Indian patients. The time from diagnosis to complication was comparable (log rank p = 0.152). Antiglycan serology did not correlate with a complicated early course in either cohort. Conclusions: There are significant differences in patients presenting with newly diagnosed CD in India and Israel, including phenotype and distinct biomarkers at diagnosis. These differences suggest different genetic and environmental disease modifiers.

Proinflammatory mucosal-associated invariant CD8+ T cells react to gut flora yeasts and infiltrate multiple sclerosis brain

The composition of the intestinal microbiota plays a critical role in shaping the immune system. Modern lifestyle, the inappropriate use of antibiotics, and exposure to pollution have significantly affected the composition of commensal microorganisms. The intestinal microbiota has been shown to sustain inappropriate autoimmune responses at distant sites in animal models of disease, and may also have a role in immune-mediated central nervous system (CNS) diseases such as multiple sclerosis (MS). We studied the composition of the gut mycobiota in fecal samples from 27 persons with MS (pwMS) and in 18 healthy donors (HD), including 5 pairs of homozygous twins discordant for MS. We found a tendency towards higher fungal abundance and richness in the MS group, and we observed that MS twins showed a higher rate of food-associated strains, such as Saccharomyces cerevisiae. We then found that in pwMS, a distinct population of cells with antibacterial and antifungal activity is expanded during the remitting phase and markedly decreases during clinically and/or radiologically active disease. These cells, named MAIT (mucosal-associated invariant T cells) lymphocytes, were significantly more activated in pwMS compared to HD in response to S. cerevisiae and Candida albicans strains isolated from fecal samples. This activation was also mediated by fungal-induced IL-23 secretion by innate immune cells. Finally, immunofluorescent stainings of MS post-mortem brain tissues from persons with the secondary progressive form of the disease showed that MAIT cells cross the blood–brain barrier (BBB) and produce pro-inflammatory cytokines in the brain. These results were in agreement with the hypothesis that dysbiosis of the gut microbiota might determine the inappropriate response of a subset of pathogenic mucosal T cells and favor the development of systemic inflammatory and autoimmune diseases.

Immunosurveillance of Candida albicans commensalism by the adaptive immune system

The fungal microbiota (mycobiota) is an integral part of the microbial community colonizing the body surfaces and is involved in many key aspects of human physiology, while an imbalance of the fungal communities, termed fungal dysbiosis, has been described in pathologies ranging from infections to inflammatory bowel disease. Commensal organisms, such as the fungus Candida albicans, induce antigen-specific immune responses that maintain immune homeostasis. Adaptive immune mechanisms are vital in this process, while deficiencies in adaptive immunity are linked to fungal infections. We start to understand the mechanisms by which a shift in mycobiota composition, in particular in C. albicans abundance, is linked to immunopathological conditions. This review discusses the mechanisms that ensure continuous immunosurveillance of C. albicans during mucosal colonization, how these protective adaptive immune responses can also promote immunopathology, and highlight therapeutic advances against C. albicans-associated disease.

B cell class switching in intestinal immunity in health and disease

The gastrointestinal tract is colonized by trillions of commensal microorganisms that collectively form the microbiome and make essential contributions to organism homeostasis. The intestinal immune system must tolerate these beneficial commensals, whilst preventing pathogenic organisms from systemic spread. Humoral immunity plays a key role in this process, with large quantities of immunoglobulin (Ig)A secreted into the lumen on a daily basis, regulating the microbiome and preventing bacteria from encroaching on the epithelium. However, there is an increasing appreciation of the role of IgG antibodies in intestinal immunity, including beneficial effects in neonatal immune development, pathogen and tumour resistance, but also of pathological effects in driving chronic inflammation in inflammatory bowel disease (IBD). These antibody isotypes differ in effector function, with IgG exhibiting more proinflammatory capabilities compared with IgA. Therefore, the process that leads to the generation of different antibody isotypes, class-switch recombination (CSR), requires careful regulation and is orchestrated by the immunological cues generated by the prevalent local challenge. In general, an initiating signal such as CD40 ligation on B cells leads to the induction of activation-induced cytidine deaminase (AID), but a second cytokine-mediated signal determines which Ig heavy chain is expressed. Whilst the cytokines driving intestinal IgA responses are well-studied, there is less clarity on how IgG responses are generated in the intestine, and how these cues might become dysfunctional in IBD. Here, we review the key mechanisms regulating class switching to IgA vs IgG in the intestine, processes that could be therapeutically manipulated in infection and IBD.

Anti-Microbial Antibody Response is Associated With Future Onset of Crohn's Disease Independent of Biomarkers of Altered Gut Barrier Function, Subclinical Inflammation, and Genetic Risk

BACKGROUND AND AIMS

Altered host immune reactivity to microbial antigens is hypothesized to trigger the onset of Crohn's disease (CD). We aimed to assess whether increased serum anti-microbial antibody response in asymptomatic first-degree relatives (FDRs) of CD patients is an independent risk factor for future CD development.

METHODS

We measured host serum antibody response to 6 microbial antigens at enrollment (Prometheus enzyme-linked immunosorbent assay test: anti-Saccharomyces cerevisiae antibodies immunoglobulin A/immunoglobulin G, anti-OmpC, anti-A4-Fla2, anti-FlaX, anti-CBir1) and derived the sum of positive antibodies (AS). We used samples at enrollment of prospectively followed healthy FDRs from a nested case-control cohort of the Crohn's and Colitis Canada Genetics Environment Microbial Project. Those who later developed CD (n = 77) were matched 1:4 by age, sex, follow-up duration, and geographic location with control FDRs remaining healthy (n = 307). To address our research aims, we fitted a multivariable conditional logistic regression model and performed causal mediation analysis.

RESULTS

High baseline AS (≥2) (43% of cases, 11% of controls) was associated with higher risk of developing CD (adjusted odds ratio, 6.5; 95% confidence interval, 3.4-12.7; P < .001). Importantly, this association remained significant when adjusted for markers of gut barrier function, fecal calprotectin, C-reactive protein, and CD-polygenic risk score, and in subjects recruited more than 3 years before diagnosis. Causal mediation analysis showed that the effect of high AS on future CD development is partially mediated (42%) via preclinical gut inflammation.

CONCLUSIONS

Our results suggest that increased anti-microbial antibody responses are associated with risk of future development of CD, independent of biomarkers of abnormal gut barrier function, subclinical inflammation, and CD-related genetic risks. This suggests that anti-microbial antibody responses are an early predisease event in the development of CD.

The role of gut mycobiome in health and diseases

The gut microbiome comprised of microbes from multiple kingdoms, including bacteria, fungi, and viruses. Emerging evidence suggests that the intestinal fungi (the gut "mycobiome") play an important role in host immunity and inflammation. Advances in next generation sequencing methods to study the fungi in fecal samples and mucosa tissues have expanded our understanding of gut fungi in intestinal homeostasis and systemic immunity in health and their contribution to different human diseases. In this review, the current status of gut mycobiome in health, early life, and different diseases including inflammatory bowel disease, colorectal cancer, and metabolic diseases were summarized.

The role of mycobiota-genotype association in inflammatory bowel diseases: a narrative review

Inflammatory bowel disease (IBD) is a chronic inflammatory disease affecting various parts of the gastrointestinal tract. A majority of the current evidence points out the involvement of intestinal dysbiosis in the IBD pathogenesis. Recently, the association of intestinal fungal composition With IBD susceptibility and severity has been reported. These studies suggested gene polymorphisms in the front line of host defense against intestinal microorganisms are considered to play a role in IBD pathogenesis. The studies have also detected increased susceptibility to fungal infections in patients carrying IBD-related mutations. Therefore, a literature search was conducted in related databases to review articles addressing the mycobiota-genotype association in IBD.

Systematic Review: The Gut Microbiome and Its Potential Clinical Application in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic relapsing-remitting systemic disease of the gastrointestinal tract. It is well established that the gut microbiome has a profound impact on IBD pathogenesis. Our aim was to systematically review the literature on the IBD gut microbiome and its usefulness to provide microbiome-based biomarkers. A systematic search of the online bibliographic database PubMed from inception to August 2020 with screening in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was conducted. One-hundred and forty-four papers were eligible for inclusion. There was a wide heterogeneity in microbiome analysis methods or experimental design. The IBD intestinal microbiome was generally characterized by reduced species richness and diversity, and lower temporal stability, while changes in the gut microbiome seemed to play a pivotal role in determining the onset of IBD. Multiple studies have identified certain microbial taxa that are enriched or depleted in IBD, including bacteria, fungi, viruses, and archaea. The two main features in this sense are the decrease in beneficial bacteria and the increase in pathogenic bacteria. Significant differences were also present between remission and relapse IBD status. Shifts in gut microbial community composition and abundance have proven to be valuable as diagnostic biomarkers. The gut microbiome plays a major role in IBD, yet studies need to go from casualty to causality. Longitudinal designs including newly diagnosed treatment-naïve patients are needed to provide insights into the role of microbes in the onset of intestinal inflammation. A better understanding of the human gut microbiome could provide innovative targets for diagnosis, prognosis, treatment and even cure of this relevant disease.

Inflammatory Bowel Diseases (IBD) and the Microbiome-Searching the Crime Scene for Clues

Inflammatory bowel diseases (IBD) develop via convergence of environmental, microbial, immunological, and genetic factors. Alterations in the gut microbiota have been associated with development and progression of IBD, but it is not clear which populations of microbes are involved or how they might contribute to IBD. We review the genetic and environmental factors affecting the gut microbiota, the roles of gut microbes and their bioproducts in the development and clinical course of IBD, and strategies by which microbiome-based therapies can be used to prevent, manage, and eventually cure IBD. We discuss research findings that help bridge the gap between the basic sciences and clinical application.

Crohn's disease and environmental contamination: Current challenges and perspectives in exposure evaluation

Although the incidence of Crohn's disease has increased worldwide over the past 30 years, the disorder's exact causes and physiological mechanisms have yet to be determined. Given that genetic determinants alone do not explain the development of Crohn's disease, there is growing interest in "environmental" determinants. In medical science, the term "environment" refers to both the ecological and social surroundings; however, most published studies have focused on the latter. In environmental and exposure sciences, the term "environment" mostly relates to contamination of the biotope. There are many unanswered questions on how environmental hazards might contribute to the pathogenesis of Crohn's disease. Which pollutants should be considered? Which mechanisms are involved? And how should environmental contamination and exposure be evaluated? The objective was to perform a systematic review of the literature on Crohn's disease and environmental contamination. We searched the PubMed, Google Scholar, Scopus, ISI Web of Science and Prospero databases. We considered all field studies previous to April 2019 conducted on human health indicators, and evaluating exposure to all type of physical, biological and chemical contamination of the environment. The lack of clear answers to date can be ascribed to the small total number of field studies (n = 16 of 39 publications, most of which were conducted by pioneering medical scientists), methodological differences, and the small number of contaminants evaluated. This make it impossible to conduct a coherent and efficient meta-analysis. Based on individual analysis of available studies, we formulated five recommendations on improving future research: (i) follow up the currently identified leads - especially metals and endocrine disruptors; (ii) explore soil contamination; (iii) gain a better knowledge of exposure mechanisms by developing transdisciplinary studies; (iv) identify the most plausible contaminants by developing approaches based on the source-to-target distance; and (v) develop registries and cohort-based analyses.

The mycobiota of the human body: a spark can start a prairie fire

Mycobiota are inseparable from human health, shaking up the unique position held by bacteria among microorganisms. What is surprising is that this seemingly small species can trigger huge changes in the human body. Dysbiosis and invasion of mycobiota are confirmed to cause disease in different parts of the body. Meanwhile, our body also produces corresponding immune changes upon mycobiota infection. Several recent studies have made a connection between intestinal mycobiota and the human immune system. In this review, we focus on questions related to mycobiota, starting with an introduction of select species, then we summarize the typical diseases caused by mycobiota in different parts of the human body. Moreover, we constructed a framework for the human anti-fungal immune system based on genetics and immunology. Finally, the progression of fungal detection methods is also reviewed.

Comparative immunophenotyping of Saccharomyces cerevisiae and Candida spp. strains from Crohn's disease patients and their interactions with the gut microbiome

Investigation of the fungal communities in animal models of Inflammatory Bowel Diseases (IBD) showed a controversial role of Saccharomyces cerevisiae and Candida spp. In health and disease. These conflicting observations could be ascribed to immunogenic differences among co-specific strains. To assess the relevance of intra-strains differences on yeast immunogenicity and impact on the microbiota, we screened S. cerevisiae and Candida spp. Strains isolated from fecal samples of IBD patients. We compared the cytokine profiles, obtained upon stimulation of Peripheral Blood Mononuclear Cells (PBMCs) and Dendritic Cells with different yeast strains, and evaluated the relationship between strain’s cell wall sugar amount and immune response. Moreover, the gut microbiota composition was explored in relation to fungal isolation from fecal samples by metabarcoding analysis. The comparison of cytokine profiles showed strain dependent rather than species-dependent differences in immune responses. Differences in immunogenicity correlated with the cell wall composition of S. cerevisiae intestinal strains. Stimulation of human healthy PBMCs with different strains showed a pro-inflammatory IL-6 response counterbalanced by IL-10 production. Interestingly, Crohn’s (CD) patients responded differently to “self” and “non-self” strains, eliciting pure Th1 or Th17 cytokine patterns. The differences observed in vitro were recapitulated in vivo, where different strains contributed in dramatically different ways to local epithelial activity and to the inflammation of wild type and Interleukin-deficient mice. Furthermore, we observed that the gut microbiota profiles significantly differentiated according to the presence of Saccharomyces or Candida spp. or the absence of fungal isolates in fecal samples. Our results show the importance to deepen metagenomics and immunophenotyping analyses to the strain level, to elucidate the role of fungal and bacterial communities in health and disease.

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Previous studies indicated an involvement of gut mycobiome in IBD pathogenesis.

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We screened for immunomodulatory properties S. cerevisiae and Candida strains from IBD patients.

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The fungal immunomodulation depends on strain-rather than species-specific traits.

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Differences in immunogenicity correlate with the cell wall composition of gut strains.

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CD patients responded differently to “self” and “non-self” strains.

Identification of Patulin from Penicillium coprobium as a Toxin for Enteric Neurons

The identification and characterization of fungal commensals of the human gut (the mycobiota) is ongoing, and the effects of their various secondary metabolites on the health and disease of the host is a matter of current research. While the neurons of the central nervous system might be affected indirectly by compounds from gut microorganisms, the largest peripheral neuronal network (the enteric nervous system) is located within the gut and is exposed directly to such metabolites. We analyzed 320 fungal extracts and their effect on the viability of a human neuronal cell line (SH-SY5Y), as well as their effects on the viability and functionality of the most effective compound on primary enteric neurons of murine origin. An extract from P. coprobium was identified to decrease viability with an EC₅₀ of 0.23 ng/µL in SH-SY5Y cells and an EC₅₀ of 1 ng/µL in enteric neurons. Further spectral analysis revealed that the effective compound was patulin, and that this polyketide lactone is not only capable of evoking ROS production in SH-SY5Y cells, but also diverse functional disabilities in primary enteric neurons such as altered calcium signaling. As patulin can be found as a common contaminant on fruit and vegetables and causes intestinal injury, deciphering its specific impact on enteric neurons might help in the elaboration of preventive strategies.

Dependence of Colonization of the Large Intestine by Candida on the Treatment of Crohn's Disease

The aim of this study was to determine if there are quantitative differences in Candida fungi between pediatric patients with Crohn’s disease (before and after exclusive enteral nutrition (EEN), and the biologic therapy with anti-tumor necrosis factor alpha – (IFX)), and healthy controls. DNA was isolated from fecal samples and PCR was used to determine the number of fungal cells. Both therapeutic interventions resulted in a statistically significant decrease in Pediatric Crohn’s Disease Activity Index. The numbers of Candida decreased during both therapeutic intervention but the difference was statistically significant for the IFX intervention only (p = 0.045). Moreover, fungi population in both study groups declined during intervention when compared to the control group but the difference was significant before treatment only in the IFX group (p = 0.013). The total distribution of Candida with both IFX and EEN as well as in the control group differed significantly (p = 0.01) before treatment only. No correlation between the numbers of Candida and disease activity as well as the following biochemical parameters: serum iron concentration, protein or glucose level were found. It cannot be ruled out that, in combination with genetic and immunological disorders, fungi can contribute to the initiation of the disease process and perpetuation of active inflammation.

SYK-CARD9 Signaling Axis Promotes Gut Fungi-Mediated Inflammasome Activation to Restrict Colitis and Colon Cancer

Fungi represent a significant proportion of the gut microbiota. Aberrant immune responses to fungi are frequently observed in inflammatory bowel diseases (IBD) and colorectal cancer (CRC), and mutations in the fungal-sensing pathways are associated with the pathogenesis of IBD. Fungal recognition receptors trigger downstream signaling via the common adaptor protein CARD9 and the kinase SYK. Here we found that commensal gut fungi promoted inflammasome activation during AOM-DSS-induced colitis. Myeloid cell-specific deletion of Card9 or Syk reduced inflammasome activation and interleukin (IL)-18 maturation and increased susceptibility to colitis and CRC. IL-18 promoted epithelial barrier restitution and interferon-γ production by intestinal CD8⁺ T cells. Supplementation of IL-18 or transfer of wild-type myeloid cells reduced tumor burden in AOM-DSS-treated Card9^-/- and Syk^fl/flLysM^Cre/+ mice, whereas treatment with anti-fungal agents exacerbated colitis and CRC. CARD9 deletion changes the gut microbial landscape, suggesting that SYK-CARD9 signaling maintains a microbial ecology that promotes inflammasome activation and thereby restrains colitis and colon tumorigenesis.

Population genomics reveals evolution and variation of Saccharomyces cerevisiae in the human and insects gut

The quest to discover the variety of ecological niches inhabited by Saccharomyces cerevisiae has led to research in areas as diverse as wineries, oak trees and insect guts. The discovery of fungal communities in the human gastrointestinal tract suggested the host's gut as a potential reservoir for yeast adaptation. Here, we report the existence of yeast populations associated with the human gut (HG) that differ from those isolated from other human body sites. Phylogenetic analysis on 12 microsatellite loci and 1715 combined CDSs from whole-genome sequencing revealed three subclusters of HG strains with further evidence of clonal colonization within the host's gut. The presence of such subclusters was supported by other genomic features, such as copy number variation, absence/introgressions of CDSs and relative polymorphism frequency. Functional analysis of CDSs specific of the different subclusters suggested possible alterations in cell wall composition and sporulation features. The phenotypic analysis combined with immunological profiling of these strains further showed that sporulation was related with strain-specific genomic characteristics in the immune recognition pattern. We conclude that both genetic and environmental factors involved in cell wall remodelling and sporulation are the main drivers of adaptation in S. cerevisiae populations in the human gut.

The Gut Microbiota in the Pathogenesis and Therapeutics of Inflammatory Bowel Disease

In the twenty first century, the changing epidemiology of inflammatory bowel disease (IBD) globally with increasing disease incidence across many countries relates to the altered gut microbiota, due to a combinatorial effect of environmental factors, human immune responses and genetics. IBD is a gastrointestinal disease associated with a gut microbial dysbiosis, including an expansion of facultative anaerobic bacteria of the family Enterobacteriaceae. Advances in high-throughput sequencing enable us to entangle the gut microbiota in human health and IBD beyond the gut bacterial microbiota, expanding insights into the mycobiota, virobiota and helminthes. Caudovirales (viruses) and Basidiomycota, Ascomycota, and Candida albicans (fungi) are revealed to be increased in IBD. The deconvolution of the gut microbiota in IBD lays the basis for unveiling the roles of these various gut microbiota components in IBD pathogenesis and being conductive to instructing on future IBD diagnosis and therapeutics. Here we comprehensively elucidate the alterations in the gut microbiota in IBD, discuss the effect of diets in the gut microbiota in relation to IBD, and illustrate the potential of manipulation of gut microbiota for IBD therapeutics. The therapeutic strategy of antibiotics, prebiotics, probiotics and fecal microbiota transplantation will benefit the effective application of precision microbiome manipulation in IBD.

Fungi in Gastrointestinal Tracts of Human and Mice: from Community to Functions

Fungi are often ignored in studies on gut microbes because of their low level of presence (making up only 0.1% of the total microorganisms) in the gastrointestinal tract (GIT) of monogastric animals. Recent studies using novel technologies such as next generation sequencing have expanded our understanding on the importance of intestinal fungi in humans and animals. Here, we provide a comprehensive review on the fungal community, the so-called mycobiome, and their functions from recent studies in humans and mice. In the GIT of humans, fungi belonging to the phyla Ascomycota, Basidiomycota and Chytridiomycota are predominant. The murine intestines harbor a more diverse assemblage of fungi. Diet is one of the major factors influencing colonization of fungi in the GIT. Presence of the genus Candida is positively associated with dietary carbohydrates, but are negatively correlated with dietary amino acids, proteins, and fatty acids. However, the relationship between diet and the fungal community (and functions), as well as the underlying mechanisms remains unclear. Dysbiosis of intestinal fungi can cause invasive infections and inflammatory bowel diseases (IBD). However, it is not clear whether dysbiosis of the mycobiome is a cause, or a result of IBD. Compared to non-inflamed intestinal mucosa, the abundance and diversity of fungi is significantly increased in the inflamed mucosa. The commonly observed commensal fungal species Candida albicans might contribute to occurrence and development of IBD. Limited studies show that Candida albicans might interact with immune cells of the host intestines through the pathways associated with Dectin-1, Toll-like receptor 2 (TLR2), and TLR4. This review is expected to provide new thoughts for future studies on intestinal fungi and for new therapies to fungal infections in the GIT of human and animals.

Autologous Haematopoietic Stem Cell Transplantation (AHSCT) in Severe Crohn's Disease: A Review on Behalf of ECCO and EBMT

Despite the major recent progress in the treatment of Crohn's disease [CD], there is a subset of patients in whom the disease runs an aggressive course with progressive tissue damage requiring early and repeated surgical management. Increasing evidence supports sustained and profound improvement in gastrointestinal parameters and quality of life following high-dose immunosuppressive therapy and autologous haematopoietic stem cell transplantation [AHSCT] compared to standard therapy in this context. In addition, international transplant registry data reflect the use of AHSCT in CD outside of trials in selected patients. However, AHSCT may be associated with significant treatment-related complications with risk of transplant-related mortality. In a joint initiative, the European Crohn's and Colitis Organisation [ECCO] and the European Society for Blood and Marrow Transplantation [EBMT] have produced a state-of-the-art review of the rationale, evaluation, patient selection, stem cell mobilization and transplant procedures and long-term follow up. Given the unique spectrum of issues, we recommend that AHSCT should only be performed in experienced centres with expertise in both haematological and gastroenterological aspects of the procedure. Where possible, patients should be enrolled on clinical trials and data registered centrally. Future development should be coordinated at both national and international levels.

The Mycobiome: A Neglected Component in the Microbiota-Gut-Brain Axis

In recent years, the gut microbiota has been considered as a full-fledged actor of the gut-brain axis, making it possible to take a new step in understanding the pathophysiology of both neurological and psychiatric diseases. However, most of the studies have been devoted to gut bacterial microbiota, forgetting the non-negligible fungal flora. In this review, we expose how the role of the fungal component in the microbiota-gut-brain axis is legitimate, through its interactions with both the host, especially with the immune system, and the gut bacteria. We also discuss published data that already attest to a role of the mycobiome in the microbiota-gut-brain axis, and the impact of fungi on clinical and therapeutic research.

Specific changes of enteric mycobiota and virome in inflammatory bowel disease

One of the important features of inflammatory bowel disease (IBD) is dysbiosis of the gut microbiota. It has been well documented that changes in the commensal bacterial population are involved in IBD development. However, the function of the fungal and viral communities in IBD remains unclear. Moreover, the optimal treatment for IBD patients with opportunistic infections is still undecided. This review focused on how the enteric mycobiota and virome changes during the pathogenesis of IBD and discussed potential treatment strategies that open new insights into the managements of IBD.

Is There a Link Between H. Pylori and the Epidemiology of Crohn's Disease?

INTRODUCTION

Case control studies suggest an inverse association between Helicobacter pylori (H. pylori) and Crohn's disease (CD). It is possible this could be accounted for by confounders such as antibiotic therapy. Analyzing the geographic distribution of H. pylori and the links with the incidence and prevalence of CD would be an alternative approach to circumvent these confounders.

METHODS

The literature was searched for studies published between 1990 and 2016 that reported incidence or prevalence data for CD in random population samples in developed countries (GDP per capita >20,000 USD/year). Corresponding prevalence studies for H. pylori in these same regions were then sought matched to the same time period (±6 years). The association between the incidence and prevalence of CD and H. pylori prevalence rates were assessed before and after adjusting for GDP and life expectancy.

RESULTS

A total of 19 CD prevalence and 22 CD incidence studies from 10 European countries, Japan, USA, and Australia with date-matched H. pylori prevalence data were identified. The mean H. pylori prevalence rate was 43.4% (range 15.5-85%), and the mean rates for incidence and prevalence for CD were 6.9 and 91.0/100,000 respectively. The incidence (r = -0.469, p < 0.03) and prevalence (r = -0.527, p = 0.02) of CD was inversely and significantly associated with prevalence of H. pylori infection.

CONCLUSIONS

Our data demonstrate a significant inverse association between geographic distribution of H. pylori and CD. Thus, it is highly unlikely that the findings of previous case control studies were simply due to confounding factors such as concomitant antibiotic use in CD patients.

Probiotic normalization of Candida albicans in schizophrenia: A randomized, placebo-controlled, longitudinal pilot study

The molecules and pathways of the gut-brain axis represent new targets for developing methods to diagnose and treat psychiatric disorders. Manipulation of the gut microbiome with probiotics may be a therapeutic strategy with the potential to relieve gastrointestinal (GI) comorbidities and improve psychiatric symptoms. Candida albicans and Saccharomyces cerevisiae, commensal yeast species, can be imbalanced in the unhealthy human microbiome, and these fungal exposures were previously found elevated in schizophrenia. In a longitudinal, double-blind, placebo-controlled, pilot investigation of 56 outpatients with schizophrenia, we examined the impact of probiotic treatment on yeast antibody levels, and the relationship between treatment and antibody levels on bowel discomfort and psychiatric symptoms. We found that probiotic treatment significantly reduced C. albicans antibodies over the 14-week study period in males, but not in females. Antibody levels of S. cerevisiae were not altered in either treatment group. The highest levels of bowel discomfort over time occurred in C. albicans-seropositive males receiving the placebo. We observed trends towards improvement in positive psychiatric symptoms in males treated with probiotics who were seronegative for C. albicans. Results from this pilot study hint at an association of C. albicans seropositivity with worse positive psychiatric symptoms, which was confirmed in a larger cohort of 384 males with schizophrenia. In conclusion, the administration of probiotics may help normalize C. albicans antibody levels and C. albicans-associated gut discomfort in many male individuals. Studies with larger sample sizes are warranted to address the role of probiotics in correcting C. albicans-associated psychiatric symptoms.

IBD immunopathogenesis: A comprehensive review of inflammatory molecules

Inflammatory molecules play a crucial role in the pathogenesis of inflammatory bowel disease (IBD) such as ulcerative colitis and Crohn's disease, both of which are chronic inflammatory conditions of the gastrointestinal tract. Abnormal expressions of pro- and anti-inflammatory molecules have been described to cause an imbalance to the gut innate and adaptive immunity, and recently a large portion of research in IBD has been geared towards identifying novel molecules that may be used as potential therapeutic targets. Understanding of these inflammatory molecules has suggested that although ulcerative colitis and Crohn's disease share many common clinical symptoms and signs, they are in fact two separate clinical entities characterized by different immunopathogenesis. In this review, we comprehensively discuss the roles of numerous inflammatory molecules including but not limited to cytokines, chemokines, inflammasomes, microRNAs and neuropeptides and their expression status in ulcerative colitis and Crohn's disease in relation to their effects on the overall intestinal inflammatory process.

The Fungal Mycobiome and Its Interaction with Gut Bacteria in the Host

The advent of sequencing technology has endowed us with the capacity to study microbes constituting the human commensal community that were previously non-culturable. Much of the initial works have concentrated on the bacterial flora constituting the gut microbiome, since specimens are readily accessible in health and disease. Less, however, is understood of the “silent population”—the fungal species, also known as the mycobiome. Living in symbiosis with bacteria as commensals in our body, it is perceivable that the mycobiome exerts an inadvertent influence on the microbiome. We review here the recent knowledge gained from study of the interaction between the mycobiome and microbiome in health and disease susceptibility, immunity, and consequences from antimicrobial treatment.

Fungal Dysbiosis in Mucosa-associated Microbiota of Crohn's Disease Patients

BACKGROUND AND AIMS

Gut microbiota is involved in many physiological functions and its imbalance is associated with several diseases, particularly with inflammatory bowel diseases. Mucosa-associated microbiota could have a key role in induction of host immunity and in inflammatory process. Although the role of fungi has been suggested in inflammatory disease pathogenesis, the fungal microbiota has not yet been deeply explored. Here we analysed the bacterial and fungal composition of the mucosa-associated microbiota of Crohn's disease patients and healthy subjects.

METHODS

Our prospective, observational study evaluated bacterial and fungal composition of mucosa-associated microbiota of 23 Crohn's disease patients [16 in flare, 7 in remission] and 10 healthy subjects, using 16S [MiSeq] and ITS2 [pyrosequencing] sequencing, respectively. Global fungal load was assessed by real time quantitative polymerase chain reaction.

RESULTS

Bacterial microbiota in Crohn's disease patients was characterised by a restriction in biodiversity. with an increase of Proteobacteria and Fusobacteria. Global fungus load was significantly increased in Crohn's disease flare compared with healthy subjects [p < 0.05]. In both groups, the colonic mucosa-associated fungal microbiota was dominated by Basidiomycota and Ascomycota phyla. Cystofilobasidiaceae family and Candida glabrata species were overrepresented in Crohn's disease. Saccharomyces cerevisiae and Filobasidium uniguttulatum species were associated with non-inflamed mucosa, whereas Xylariales order was associated with inflamed mucosa.

CONCLUSIONS

Our study confirms the alteration of the bacterial microbiota and is the first demonstration of the existence of an altered fungal microbiota in Crohn's disease patients, suggesting that fungi may play a role in pathogenesis.

Immunopathogenesis of IBD: current state of the art

IBD is a chronic inflammatory condition of the gastrointestinal tract encompassing two main clinical entities: Crohn's disease and ulcerative colitis. Although Crohn's disease and ulcerative colitis have historically been studied together because they share common features (such as symptoms, structural damage and therapy), it is now clear that they represent two distinct pathophysiological entities. Both Crohn's disease and ulcerative colitis are associated with multiple pathogenic factors including environmental changes, an array of susceptibility gene variants, a qualitatively and quantitatively abnormal gut microbiota and a broadly dysregulated immune response. In spite of this realization and the identification of seemingly pertinent environmental, genetic, microbial and immune factors, a full understanding of IBD pathogenesis is still out of reach and, consequently, treatment is far from optimal. An important reason for this unsatisfactory situation is the currently limited comprehension of what are the truly relevant components of IBD immunopathogenesis. This article will comprehensively review current knowledge of the classic immune components and will expand the concept of IBD immunopathogenesis to include various cells, mediators and pathways that have not been traditionally associated with disease mechanisms, but that profoundly affect the overall intestinal inflammatory process.

Anti-Saccharomyces cerevisiae antibody titres correlate well with disease activity in children with Crohn's disease

AIM

The role of noninvasive biologic markers for disease activity is very important in children with Crohn's disease. The aim of this study was to assess an association between disease activity and quantitative serum anti-Saccharomyces cerevisiae antibody (ASCA) titres.

METHODS

Anti-Saccharomyces cerevisiae antibody immunoglobulin (Ig) A and immunoglobulin G titres, paediatric Crohn's disease activity index (PCDAI), serum albumin and C-reactive protein (CRP) were repeatedly measured simultaneously in children with Crohn's disease. A possible association between ASCA IgA and IgG titres and changes in PCDAI was examined.

RESULTS

Serial 136 measurements of ASCA IgA and IgG titres were documented in 57 children with Crohn's disease over a mean duration of 3.1 ± 2.1 years. In a univariate linear regression model, there were significant correlations between ASCA IgA titres and PCDAI (p < 0.001), CRP (p <0.01) and low serum albumin (p < 0.001), respectively. Similarly, ASCA IgG titres significantly correlated with PCDAI, CRP and low serum albumin.

CONCLUSION

Both ASCA IgA and IgG titres seemed to correlate well with clinical Crohn's disease activity in children. Measuring these antibodies may be considered during routine clinical care for those patients.

Inflammatory bowel disease

Scandinavian researchers have contributed to the present understanding of inflammatory bowel disease (IBD). Important epidemiological data and family risk factors have been reported from all the Nordic countries, original twin studies mainly from Denmark and Sweden, and relationships to cancer and surgery mostly from Sweden. In collaboration with the industry, development of medical compounds was for a long time in the front line of international research, and the Scandinavian countries participated in the clinical breakthrough of biologic treatment. At present, many Nordic centers are working in the forefront of IBD research. An increasing number of young investigators have entered the scene along with the extended distribution of University clinics and research laboratories in these countries. This presentation of IBD gives a brief overview in the fields of clinical epidemiology and molecular biology. Many areas are covered by International collaborations with partners from Nordic centers. IBD was a topic focused by the founders of Scandinavian Journal of Gastroenterology. After 50 years one may state that the journal's history reflects important pieces of scientific knowledge within these diseases. The early scope of Johannes Myren for IBD was shown through his work in the original World Association of Gastroenterology (OMG), and after 50 years we can clearly support the view that global perspectives in IBD are increasingly important.

Gut fungal microbiota: the Yin and Yang of inflammatory bowel disease

The prevalence of inflammatory bowel diseases (IBD) has been steadily increasing since 1960. They are widespread throughout Europe, North America, China, and Japan and are emerging as a global disease. The equilibrium among epithelial cells, the immune system, and the related microbiota seems to be paramount in ensuring the absence of these IBD. The role of bacteria in the setting of the gut microbiota has been thoroughly documented, but the role of fungi, which are less abundant, needs to be investigated. Our understanding of the fungal microbiota composition and its impact on IBD has greatly increased in the past 8 years. In this review, we compiled data obtained for the composition of fungal gut microbiota. Special attention was paid to the various effects of this microbial community on the IBD, i.e., the mechanisms and immune pathways involved in these interactions.

Mycobiota in gastrointestinal diseases

New insights gained through the use of state-of-the-art technologies, including next-generation sequencing, are starting to reveal that the association between the gastrointestinal tract and the resident mycobiota (fungal community) is complex and multifaceted, in which fungi are active participants influencing health and disease. Characterizing the human mycobiome (the fungi and their genome) in healthy individuals showed that the gastrointestinal tract contains 66 fungal genera and 184 fungal species, with Candida as the dominant fungal genera. Although fungi have been associated with a number of gastrointestinal diseases, characterization of the mycobiome has mainly been focused on patients with IBD and graft-versus-host disease. In this Review, we summarize the findings from studies investigating the relationship between the gut mycobiota and gastrointestinal diseases, which indicate that fungi contribute to the aggravation of the inflammatory response, leading to increased disease severity. A model explaining the mechanisms underlying the role of the mycobiota in gastrointestinal diseases is also presented. Our understanding of the contribution of the mycobiota to health and disease is still in its infancy and leaves a number of questions to be addressed. Answering these questions might lead to novel approaches to prevent and/or manage acute as well as chronic gastrointestinal disease.

Baker's yeast (Saccharomyces cerevisiae) antigen in obese and normal weight subjects

Baker's yeast (Saccharomyces cerevisiae) and its cell wall components have been used as one of the alternatives to antibiotic growth promoters in the feed industry. Antibodies to cell wall mannan of this yeast (ASCA) have been traditionally used in the study of Crohn's disease (CD). We applied ASCA in relation to obesity. This study aims (i) to determine the concentration of ASCA (immunoglobulin A [IgA] and immunoglobulin G [IgG]) in obese compared with normal weight individuals and (ii) to determine if there is a correlation between ASCA concentrations, obesity indices and C-reactive protein. Forty obese individuals (body mass index [BMI] > 35 kg m(-2) ) and 18 healthy (BMI < 25 kg m(-2) ) volunteers participated in this case-control study. Binding activity of serum IgA and IgG to the cell wall mannan of S. cerevisiae was measured by enzyme-linked immunosorbent assay. More than one-third of the obese individual (35%) showed elevated titres of ASCA compared with the control group (5%). This antibody was positively associated with weight (P = 0.01), BMI (P = 0.02) and waist circumference (P = 0.02), but not with C-reactive protein. It seems that ASCA are not only specific for CD but are also associated with obesity. S. cerevisiae or a related antigen may play a role in the matrix of this complex condition.

Microbial biofilms and gastrointestinal diseases

The majority of bacteria live not planktonically, but as residents of sessile biofilm communities. Such populations have been defined as 'matrix-enclosed microbial accretions, which adhere to both biological and nonbiological surfaces'. Bacterial formation of biofilm is implicated in many chronic disease states. Growth in this mode promotes survival by increasing community recalcitrance to clearance by host immune effectors and therapeutic antimicrobials. The human gastrointestinal (GI) tract encompasses a plethora of nutritional and physicochemical environments, many of which are ideal for biofilm formation and survival. However, little is known of the nature, function, and clinical relevance of these communities. This review summarizes current knowledge of the composition and association with health and disease of biofilm communities in the GI tract.

Candida albicans infection affords protection against reinfection via functional reprogramming of monocytes

Immunological memory in vertebrates is often exclusively attributed to T and B cell function. Recently it was proposed that the enhanced and sustained innate immune responses following initial infectious exposure may also afford protection against reinfection. Testing this concept of "trained immunity," we show that mice lacking functional T and B lymphocytes are protected against reinfection with Candida albicans in a monocyte-dependent manner. C. albicans and fungal cell wall β-glucans induced functional reprogramming of monocytes, leading to enhanced cytokine production in vivo and in vitro. The training required the β-glucan receptor dectin-1 and the noncanonical Raf-1 pathway. Monocyte training by β-glucans was associated with stable changes in histone trimethylation at H3K4, which suggests the involvement of epigenetic mechanisms in this phenomenon. The functional reprogramming of monocytes, reminiscent of similar NK cell properties, supports the concept of "trained immunity" and may be employed for the design of improved vaccination strategies.

Deficiency of N-acetylgalactosamine in O-linked oligosaccharides of IgA is a novel biologic marker for Crohn's disease

BACKGROUND

Ideal biomarkers are required to be developed for the diagnosis and prediction of the treatment of inflammatory bowel disease (IBD). We have reported that alteration of N-linked oligosaccharides of immunoglobulin (Ig) G is a novel diagnostic marker of IBD. Oligosaccharide alterations of IgA, however, have not been investigated in IBD patients.

METHODS

N- and O-linked oligosaccharides of serum IgA purified from 32 patients with Crohn's disease (CD), 30 patients with ulcerative colitis (UC), and 30 healthy volunteers (HV) were analyzed with high-performance liquid chromatography and mass spectrometry. Enzymes related to oligosaccharide attachment were investigated.

RESULTS

N-linked oligosaccharides of IgA were not different between IBD and HV. In contrast, the number of N-acetylgalactosamines per hinge glycopeptide (GalNAc/HP) in the O-linked oligosaccharides of IgA was significantly decreased in patients with CD compared with UC and HV. GalNAc/HP had high sensitivity and specificity for discriminating between CD and HV based on receiver operating characteristic analysis. Lower GalNAc/HP was associated with more severe disease activity of CD. Changes in GalNAc/HP levels in 6 weeks after treatment with infliximab were associated with the clinical activity of CD at 30 weeks. GalNAc transferase expression of naïve B cells and extent of GalNAc attachment in IgA were significantly decreased by interleukin-21 in vitro.

CONCLUSIONS

The number of GalNAc attached in the IgA O-linked glycans of CD patients was significantly decreased, and strongly correlated with the clinical activity. Alterations of GalNAc attachment in IgA could be useful as a novel diagnostic and prognostic marker of CD.

Serological antibodies in inflammatory bowel disease: a systematic review

The diagnosis of inflammatory bowel disease (IBD) is traditionally based on a combination of clinical, endoscopic, histological, and radiological criteria. However, further testing is needed in cases of diagnostic uncertainty and in predicting disease course. This systematic review focuses on the potential for 10 serological antibodies to fill these roles: pANCA, ASCA, anti-OmpC, anti-CBir1, anti-I2, ALCA, ACCA, AMCA, anti-L, and anti-C. We discuss their prevalence in IBD and health; their role in disease diagnosis and risk stratification; their stability over time; their presence in unaffected relatives; their association with genetic variants; and differences across ethnic groups. Serological antibodies have some role in primary diagnosis and in differentiating between Crohn's disease and ulcerative colitis. In indeterminate colitis, preoperative measurement of serological antibodies can help to predict the likelihood of complications among patients undergoing pouch surgery. The combined presence and magnitude of a large panel of antibodies appear to be of value in predicting disease progression. There is currently insufficient evidence to recommend the use of antibody testing to predict responses to treatment or surgery in patients with IBD.

Biomarkers in inflammatory bowel disease: current practices and recent advances

Crohn's disease and ulcerative colitis represent the two main forms of the idiopathic chronic inflammatory bowel diseases (IBD). Currently available blood and stool based biomarkers provide reproducible, quantitative tools that can complement clinical assessment to aid clinicians in IBD diagnosis and management. C-reactive protein and fecal based leukocyte markers can help the clinician distinguish IBD from noninflammatory diarrhea and assess disease activity. The ability to differentiate between forms of IBD and predict risk for disease complications is specific to serologic tests including antibodies against Saccharomyces cerevisiae and perinuclear antineutrophil cytoplasmic proteins. Advances in genomic, proteomic, and metabolomic array based technologies are facilitating the development of new biomarkers for IBD. The discovery of novel biomarkers, which can correlate with mucosal healing or predict long-term disease course has the potential to significantly improve patient care. This article reviews the uses and limitations of currently available biomarkers and highlights recent advances in IBD biomarker discovery.

Diagnostic utility of anti-Saccharomyces cerevisiae antibody (ASCA) and Interferon-γ assay in the differential diagnosis of Crohn's disease and intestinal tuberculosis

BACKGROUND

Differential diagnosis of Crohn's disease (CD) from intestinal tuberculosis (ITB) is challenging. Anti-Saccharomyces cerevisiae antibody (ASCA) is a specific serological marker for CD and INF-gamma assay (QuantiFERON-TB gold test, QFT) is a good supplementary diagnostic tool for ITB. We evaluated the clinical usefulness of ASCA and QFT for differential diagnosis of CD from ITB in Korean adults.

METHODS

A total of 147 patients suspected to have ITB or CD were prospectively enrolled from 13 hospitals. ASCA IgG and IgA serum titers were measured by ELISA, and the QFT test was also performed.

RESULTS

Thirty-two of 72 (44.4%) patients with CD were ASCA positive (titer >25U) compared to 10 of 75 ITB patients (13.3%) and 3 of 20 healthy controls (15%) (p<0.01). The QFT test was positive in 7 patients with CD (9.7%) and 50 patients with ITB (66.6%) (p<0.01). In cases which ASCA positive/QFT negative, the sensitivity, specificity, positive predictive value, and negative predictive value for the diagnosis of CD were 44.4%, 96.0%, 91.4%, and 64.3%, respectively.

CONCLUSION

ASCA is a useful diagnostic tool for CD in Korea, where ITB is prevalent. In particular, when ASCA is combined with QFT, effective differential diagnosis of CD from ITB is possible.