Familial aggregation and antimicrobial response dose-dependently affect the risk for Crohn's disease

Recent Trends in Non-Invasive Methods of Diagnosis and Evaluation of Inflammatory Bowel Disease: A Short Review

Inflammatory bowel diseases are a conglomerate of disorders causing inflammation of the gastrointestinal tract, which have gained a significant increase in prevalence in the 21st century. As they present a challenge in the terms of diagnosis as well as treatment, IBDs can present an overwhelming impact on the individual and can take a toll on healthcare costs. Thus, a quick and precise diagnosis is required in order to prevent the high number of complications that can arise from a late diagnosis as well as a misdiagnosis. Although endoscopy remains the primary method of evaluation for IBD, recent trends have highlighted various non-invasive methods of diagnosis as well as reevaluating previous ones. This review focused on the current non-invasive methods in the diagnosis of IBD, exploring their possible implementation in the near future, with the goal of achieving earlier, feasible, and cheap methods of diagnosis as well as prognosis in IBD.

Preclinical disease and preventive strategies in IBD

There is growing evidence that inflammatory bowel disease has a preclinical phase that precedes disease symptoms, during which immune system activation has already occurred and inflammatory pathways have been primed, setting the stage for disease to expand and leading up to clinical diagnosis. Gaining insight to this pre-diagnosis period could improve our knowledge about disease pathogenesis and potentially result in the detection of biomarkers that could predict disease development. The ultimate goal of such research is to identify a population at risk for developing IBD, so preventive strategies could be implemented and disease prevention be achieved.

Associations of NOD2 polymorphisms with Erysipelotrichaceae in stool of in healthy first degree relatives of Crohn's disease subjects

BACKGROUND

Genetic analyses have identified many variants associated with the risk of inflammatory bowel disease (IBD) development. Among these variants, the ones located within the NOD2 gene have the highest odds ratio of all IBD genetic risk variants. Also, patients with Crohn's disease (CD) have been shown to have an altered gut microbiome, which might be a reflection of inflammation itself or an effect of other parameters that contribute to the risk of the disease. Since NOD2 is an intracellular pattern recognition receptor that senses bacterial peptidoglycan in the cytosol and stimulates the host immune response (Al Nabhani et al., PLoS Pathog 13:e1006177, 2017), it is hypothesized that NOD2 variants represent perfect candidates for influencing host-microbiome interactions. We hypothesized that NOD2 risk variants affect the microbiome composition of healthy first degree relative (FDR) of CD patients and thus potentially contribute to an altered microbiome state before disease onset.

METHODS

Based on this, we studied a large cohort of 1546 healthy FDR of CD patients and performed a focused analysis of the association of three major CD SNPs in the coding region of the NOD2 gene, which are known to confer a 15-40-fold increased risk of developing CD in homozygous or compound heterozygous individuals.

RESULTS

Our results show that carriers of the C allele at rs2066845 was significantly associated with an increase in relative abundance in the fecal bacterial family Erysipelotrichaceae.

CONCLUSIONS

This result suggests that NOD2 polymorphisms contribute to fecal microbiome composition in asymptomatic individuals. Whether this modulation of the microbiome influences the future development of CD remains to be assessed.

Serum Biomarkers for Inflammatory Bowel Disease

Background: Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, is a chronic, inflammatory disorder of the gastrointestinal tract. As the novel therapeutic goal and biologicals are widely recognized, accurate assessment of disease and prediction of therapeutic response have become a crucial challenge in clinical practice. Also, because of the continuously rising incidence, convenient and economical methods of diagnosis and clinical assessment are urgently needed. Recently, serum biomarkers have made a great progress and become a focus in IBD study because they are non-invasive, convenient, and relatively inexpensive than are markers in biopsy tissue, stool, breath, and other body fluids.

Aims: To review the available data on serological biomarkers for IBD.

Methods: We searched PubMed using predefined key words on relevant literatures of serum biomarkers regarding diagnosis, evaluation of therapeutic efficacy, surveillance of disease activity, and assessment of prognosis for IBD.

Results: We reviewed serological biomarkers that are well-established and widely used (e.g., C-reactive protein), newly discovered biomarkers (e.g., cytokines, antibodies, and non-coding RNAs), and also recently advancements in serological biomarkers (e.g., metabolomics and proteomics) that are used in different aspects of IBD management.

Conclusions: With such a wealth of researches, to date, there are still no ideal serum biomarkers for IBD. Serum profiling and non-coding RNAs are just starting to blossom but reveal great promise for future clinical practice. Combining different biomarkers can be valuable in improving performance of disease evaluation.

Capturing the Biologic Onset of Inflammatory Bowel Diseases: Impact on Translational and Clinical Science

While much progress has been made in the last two decades in the treatment and the management of inflammatory bowel diseases (IBD)-both ulcerative colitis (UC) and Crohn's Disease (CD)-as of today these conditions are still diagnosed only after they have become symptomatic. This is a major drawback since by then the inflammatory process has often already caused considerable damage and the disease might have become partially or totally unresponsive to medical therapy. Late diagnosis in IBD is due to the lack of accurate, non-invasive indicators that would allow disease identification during the pre-clinical stage-as it is often done in many other medical conditions. Here, we will discuss what is known about the biologic onset and pre-clinical CD with an emphasis on studies conducted in patients' first degree relatives. We will then review the possible strategies to diagnose IBD very early in time including screening, available disease markers and imaging, and the possible clinical implications of treating these conditions at or close to their biologic onset. Later, we will review the potential impact of conducting translational research in IBD during the pre-clinical stage, especially focusing on the role of the microbiome in disease etiology and pathogenesis. Finally, we will highlight possible future developments in the field and how they can impact IBD management and our scientific knowledge of these conditions.

Molecular Profiling of Inflammatory Bowel Disease: Is It Ready for Use in Clinical Decision-Making?

Inflammatory bowel disease (IBD) is a heterogeneous disorder in terms of age at onset, clinical phenotypes, severity, disease course, and response to therapy. This underlines the need for predictive and precision medicine that can optimize diagnosis and disease management, provide more cost-effective strategies, and minimize the risk of adverse events. Ideally, we can leverage molecular profiling to predict the risk to develop IBD and disease progression. Despite substantial successes of genome-wide association studies in the identification of genetic variants affecting IBD susceptibility, molecular profiling of disease onset and progression as well as of treatment responses has lagged behind. Still, thanks to technological advances and good study designs, predicting phenotypes using genomics and transcriptomics in IBD has been rapidly evolving. In this review, we summarize the current status of prediction of disease risk, clinical course, and response to therapy based on clinical case presentations. We also discuss the potential and limitations of the currently used approaches.

Serum anti-glycan-antibodies in relatives of patients with inflammatory bowel disease

BACKGROUND

Serum anti-glycan antibodies are a promising tool for differential diagnosis, disease stratification and prediction of Crohn's disease (CD). To investigate possible heritability of the markers we assessed the presence of serum anti-glycan antibodies in affected and unaffected relatives of patients with CD.

METHODS

Serum samples of 169 IBD patients of the German inflammatory bowel disease (IBD) network (140 CD & 29 Ulcerative colitis (UC)), 349 relatives of CD patients, 63 relatives of UC patients and 46 healthy controls were tested for the presence of anti-glycan antibodies by ELISA in a blinded fashion. Clinical data of the IBD patients and controls were available.

RESULTS

A higher proportion of non-affected CD relatives was positive for anti-glycan antibodies compared to healthy subjects. No inheritance of a specific pattern of anti-glycan antibodies could be detected. No difference in marker expression depending on the degree of relationship in the non-affected relatives was noted and the presence of family history did not lead to a difference in marker levels in the affected CD subjects.

CONCLUSIONS

Non-affected CD relatives had a higher frequency of anti-glycan antibodies compared to healthy subjects. This difference was mild and was found to be true for the overall reactivity to glycan antigens, but not for specific patterns. This may indicate an inherited mechanism resulting in a non-specific increased reactivity to microbial antigens in IBD.

Familial and ethnic risk in inflammatory bowel disease

Familial aggregation in inflammatory bowel disease (IBD) has been established for several decades, reflecting shared genetic and environmental susceptibility. A positive family history remains the strongest recognizable risk factor for the development of IBD and is reported in around 8-12% of IBD patients. Crohn’s disease shows a more frequent familial pattern than ulcerative colitis. The risk of developing IBD in first-degree relatives of an affected proband is increased 4- to 8-fold. The risk for twins and children born from couples who both have IBD is also substantially higher; a cumulative effect of the number of family members affected has been described, with the highest incidence being described for families with three or more affected members. Herein, we review the available evidence regarding familial IBD, and briefly discuss the variation of IBD across different races and ethnicities, hoping to provide a useful update and a practical guide that can serve clinicians as a guide for counseling.

Management Strategies to Improve Outcomes of Patients With Inflammatory Bowel Diseases

Strategies for management of inflammatory bowel diseases are shifting from simple control of symptoms toward full control of these diseases (clinical and endoscopic remission), with the final aim of blocking their progression and preventing bowel damage and disability. New goals have been proposed for treatment, such as treat to target and tight control based on therapeutic monitoring and early intervention. For patients who achieve clinical remission, there is often interest in discontinuation of therapy due to safety or economic concerns. We review the evidence supporting these emerging paradigms, the reasons that early effective treatment can alter progression of inflammatory bowel diseases, the importance of examining objective signs of inflammation, and the safety of reducing treatment dosage. We also discuss recent findings regarding personalization of care, including factors that predict patient outcomes and response to therapies, as well as preventative strategies.

Detecting Familial Aggregation

In addition to characterizing the distribution of genetic features of populations (mutation and allele frequencies; measures of Hardy-Weinberg equilibrium), genetic epidemiology and statistical genetics aim to explore and define the role of genomic variation in risk of disease or variation in traits of interest. To facilitate this kind of exploration, genetic epidemiology and statistical genetics address a series of questions: 1. Does the disease tend to cluster in families more than expected by chance alone? 2. Does the disease appear to follow a particular genetic model of transmission in families? 3. Does variation at a particular genomic position tend to cosegregate with disease in families? 4. Do specific genetic variants tend to be carried more frequently by those with disease than by those without these variants in a given population (or across families)? The first question can be examined using studies of familial aggregation or correlation. An ancillary question: "how much of the susceptibility to disease (or variation in disease-related traits) might be accounted for by genetic factors?" is typically answered by estimating heritability, the proportion of variance in a trait or in risk to a disease attributable to genetics. The second question can be formally tested using pedigrees for which disease affection status or trait values are available through a modeling approach known as segregation analysis. The third question can be answered with data on genomic markers in pedigrees with affected members informative for linkage, where meiotic cross-over events are estimated or assessed. The fourth question is answerable using genotype data on genomic markers on unrelated affected and unaffected individuals and/or families with affected members and unaffected members. All of these questions can also be explored for quantitative (or continuously distributed) traits by examining variation in trait values between family members or between unrelated individuals. While each of these questions and the analytical approaches for answering them is explored extensively in subsequent chapters (heritability in Chapters 8 and 9 ; segregation in Chapter 12 ; linkage in Chapters 13 - 17 ; and association in Chapters 18 - 20 ), this chapter focuses on statistical methods to address questions of familial aggregation of qualitative phenotypes (e.g., disease status) or quantitative phenotypes.While studies exploring genotype-phenotype correlations are arguably the most important and common type of statistical genetic study performed, these studies are performed under the assumption that genetic contributors at least partially explain risk of a disease or a trait of interest. This may not always be the case, especially with diseases or traits known to be strongly influenced by environmental factors. For this reason, before any of the last three questions described above can be answered, it is important to ask first whether the disease clusters among family members more than unrelated persons, as this constitutes evidence of a possible heritable contribution to disease, justifying the pursuit of studies answering the other questions. In this chapter, the underlying principles of familial aggregation studies are addressed to provide an understanding and set of analytical tools to help answer the question if diseases or traits of interest are likely to be heritable and therefore justify subsequent statistical genetic studies to identify specific genetic causes.

Concordance in Anti-OmpC and Anti-I2 Indicate the Influence of Genetic Predisposition: Results of a European Study of Twins with Crohn's Disease

BACKGROUND AND AIMS

An adaptive immunological response to microbial antigens has been observed in Crohn's disease (CD). Intriguingly, this serological response precedes the diagnosis in some patients and has also been observed in healthy relatives. We aimed to determine whether genetic factors are implicated in this response in a CD twin cohort.

METHODS

In total, 82 twin pairs (Leuven n = 13, Maastricht n = 8, Örebro n = 61) took part: 81 pairs with CD (concordant monozygotic n = 16, discordant monozygotic n = 22, concordant dizygotic n = 3, discordant dizygotic n = 40) and 1 monozygotic pair with both CD and ulcerative colitis. Serology for Pseudomonas fluorescens-related protein (anti-I2), Escherichia coli outer membrane porin C (anti-OmpC), CBir1flagellin (anti-CBir1) and antibodies to oligomannan (anti-Saccharomyces cerevisiae antibody [ASCA]) was determined by standardized enzyme-linked immunoassay.

RESULTS

All markers were more often present in CD twins than in their healthy twin siblings. Using the intraclass correlation coefficient (ICC), agreements in concentrations of anti-OmpC and anti-I2 were observed in discordant monozygotic but not in discordant dizygotic twin pairs with CD (anti-OmpC, ICC 0.80 and -0.02, respectively) and (anti-I2, ICC 0.56 and 0.05, respectively). In contrast, no agreements were found in anti-CBir, immunoglobulin (Ig) G ASCA and ASCA IgA.

CONCLUSIONS

We show that anti-I2 and anti-CBir1 statuses have specificity for CD and confirm previous reported specificities for anti-OmpC and ASCA. Based on quantitative analyses and observed ICCs, genetics seems to predispose to the anti-OmpC and anti-I2 response but less to ASCA and anti-CBir1 responses.

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.

The genetic architecture of inflammatory bowel disease: past, present and future

PURPOSE OF REVIEW

Genome-wide association studies (GWAS) have helped to understand the genetic basis and pathogenesis of inflammatory bowel disease (IBD). However, understanding the functional and clinical consequences of the associated alleles has not followed the same pace. In this review, we discuss how studying the genetic predisposition to IBD has increased our understanding about IBD pathogenesis and how epigenetics is becoming more and more important. We describe the potential clinical applications of genetics, and provide important challenges in the field and the future steps to be taken.

RECENT FINDINGS

GWAS and meta-analyses have identified 163 loci associated with IBD, and have implicated key pathways in IBD pathogenesis. Only few of the association signals correspond to nonsynonymous coding variation with a clear effect on protein function. The majority of signals involve noncoding genetic variation, of which a large part is related to gene expression changes. More recently, expression and epigenetic studies in IBD are increasingly being reported, and have shown that many effects seem to be highly cell-type specific.Predictive genetic testing will not be for the immediate future for the majority of IBD patients. However, for the subset of patients with very-early onset IBD, several causal mutations have been found. Predictive genetic panels for these adolescents presenting with a very severe disease course, and/or families with high penetrance of disease will be of benefit.

SUMMARY

Genetic, transcriptomic and epigenetic studies have offered exciting clues about IBD pathogenesis but are unlikely to provide all answers. To fully grasp the function of disease-associated genetic variants, identifying causal genes and translating this knowledge into predictive biomarkers and new treatments, we should now integrate all these disciplines.

Diagnostic and Prognostic Microbial Biomarkers in Inflammatory Bowel Diseases

The microbiome plays multifaceted roles in the pathogenesis of inflammatory bowel diseases (IBD). Accordingly, the clinical challenge of patient heterogeneity in disease phenotype and response to treatment should in part be addressed by biomarkers that detect the host response to microbiota, and the levels of microbial taxa and products eliciting the host response in susceptible individuals. Molecular analysis has revealed much evidence for microbial taxonomic membership and microbial products in association with IBD, but their utility as clinical biomarkers is still in its infancy. A rich area of progress has been the development and validation of host serologic microbial biomarkers, which have achieved a distinctive position in the diagnosis and prognosis in IBD, and as a template for defining other categories of microbial biomarkers in disease state and phenotype.

Intestinal Microbiota and the Innate Immune System - A Crosstalk in Crohn's Disease Pathogenesis

Crohn's disease (CD) is a chronic, relapsing inflammatory disorder that can occur anywhere along the gastrointestinal tract. The precise etiology of CD is still unclear but it is widely accepted that a complex series of interactions between susceptibility genes, the immune system and environmental factors are implicated in the onset and perpetuation of the disease. Increasing evidence from experimental and clinical studies implies the intestinal microbiota in disease pathogenesis, thereby supporting the hypothesis that chronic intestinal inflammation arises from an abnormal immune response against the microorganisms of the intestinal flora in genetically susceptible individuals. Given that CD patients display changes in their gut microbiota composition, collectively termed "dysbiosis," the question raises whether the altered microbiota composition is a cause of disease or rather a consequence of the inflammatory state of the intestinal environment. This review will focus on the crosstalk between the gut microbiota and the innate immune system during intestinal inflammation, thereby unraveling the role of the microbiota in CD pathogenesis.

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.

Increased risk of varicella zoster virus infection in inflammatory bowel disease in an Asian population: a nationwide population-based cohort study

PURPOSE

Whether patients with inflammatory bowel disease (IBD) exhibit a high risk of developing varicella zoster virus (VZV) infection in Asian populations remains inconclusive. We investigated the causal relationship between two diseases by analysing the Taiwan National Health Insurance Research Database.

PATIENTS AND METHODS

Based on a universal insurance claims database, we enrolled 7055 IBD patients and 28,220 age- and sex-matched controls. We calculated the hazard ratios (HRs) and 95% confidence intervals (CIs) of the herpes zoster virus (HZV) in the IBD and comparison cohorts, using the Cox proportional hazards regression model.

RESULTS

Patients with IBD exhibited significantly higher risk of the HZV compared with the controls (adjusted HRs, 1.42; 95% CI, 1.27-1.60). Further analysis indicated that male patients (adjusted HRs, 1.61; 95% CI, 1.35-1.92), aged 35-44 (adjusted HRs, 1.47; 95% CI, 1.08-2.01) and aged 65 years and older (adjusted HRs, 1.47; 95% CI, 1.19-1.80), and patients without comorbidities (adjusted HRs, 1.44; 95% CI, 1.26-1.66), exhibited excessive risks of VZV infection. Moreover, our findings show that the overall risk of developing VZV infection increased risk from 1.03 (95% CI, 0.90-1.18) (≤ 2 visits) to 9.76 (95% CI, 7.60-12.5) (> 4 visits), which correlates positively with the frequency of medical visits (trend test p < 0.0001).

CONCLUSION

Patients with IBD, particularly men aged 35-44/65 years and over, and patients without comorbidities, are associated with a long-term risk of VZV infection. The excessive risk of VZV infection should be considered for administering vaccines to IBD patients.

Systematic review: new serological markers (anti-glycan, anti-GP2, anti-GM-CSF Ab) in the prediction of IBD patient outcomes. Autoimmun Rev. 2015;14:231-245. [PMID: 25462578 DOI: 10.1016/j.autrev.2014.11.004]

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.

IRGM rs13361189 polymorphism may contribute to susceptibility to Crohn's disease: A meta-analysis

The aim of the present meta-analysis was to evaluate the correlation between a common polymorphism, rs13361189 C>T in the immunity-related GTPase M (IRGM) gene, and susceptibility to Crohn's disease (CD). The PubMed, CISCOM, CINAHL, Web of Science, Google Scholar, EBSCO, Cochrane Library and CBM databases were investigated from database inception through to October 1, 2013 without the application of any language restrictions. The meta-analysis was performed using STATA 12.0 software and the relative risk (RR) with a 95% confidence interval (CI) was calculated. Seven case-control studies were included with a total of 3,093 CD patients and 3,227 healthy control subjects. The results of the meta-analysis revealed that the IRGM rs13361189 polymorphism correlates with an increased risk of CD (T allele versus C allele: RR=1.25 with 95% CI, 1.04-1.50; P=0.016 and CT + TT versus CC: RR=1.21 with 95% CI, 1.03-1.42; P=0.018). A subgroup analysis conducted using a genotyping method indicated that the IRGM rs13361189 polymorphism was correlated with an increased risk of CD in the TaqMan^® (T allele versus C allele: RR=1.32 with 95% CI, 1.01-1.73; P=0.042) and the polymerase chain reaction-restriction fragment length polymorphism subgroups (T allele versus C allele: RR=1.80 with 95% CI, 1.32-2.45; P<0.001 and CT + TT versus CC: RR=1.61 with 95% CI, 1.19-2.18; P=0.018). However, no correlation was observed in the direct sequencing subgroup (P>0.05). Further subgroup analysis by sample size demonstrated significant correlations between the IRGM rs13361189 polymorphism and an increased risk of CD in the large sample-size subgroup (T allele versus C allele: RR=1.46 with 95% CI, 1.26-1.68; P<0.001 and CT + TT versus CC: RR=1.40 with 95% CI, 1.21-1.62; P<0.001). However, no correlation was identified between the IRGM rs13361189 polymorphism and CD risk in the small sample-size subgroup (P>0.05). The present meta-analysis indicated that the IRGM rs13361189 polymorphism may contribute to susceptibility to CD. Thus, IRGM rs13361189 polymorphism may be a potential biomarker for the early diagnosis of CD.

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

BACKGROUND

Antibodies directed towards bacterial antigens are considered as serological markers of Crohn's disease. Their role in disease pathogenesis is still under investigation.

AIM

Assess the serologic response towards microbial antigens in Crohn's disease patients, their unaffected first-degree relatives and healthy controls.

METHODS

This retrospective study included 60 Crohn's disease patients, 86 unaffected first-degree relatives and 100 healthy controls. Their sera were tested for anti-chitobioside, anti-laminaribioside, anti-mannobioside, anti-Saccharomyces cerevisiae and anti-outer membrane porin C of Escherichia coli.

RESULTS

The prevalence of anti-chitobioside and anti-laminaribioside was higher in Crohn's disease patients and their first-degree relatives than in healthy controls (51.67%, 61.63% and 8%, respectively, for anti-chitobioside and 76.17%, 88.37% and 23.00% for anti-laminaribioside; p<0.0001). The cumulative semiquantitative immune response against all the tested antibodies was higher in unaffected relatives than in healthy controls (p<0.001). The quantitative analysis revealed that serum levels of anti-chitobioside, anti-laminaribioside and anti-mannobioside were similar in first-degree relatives and Crohn's disease patients and higher than healthy controls (p<0.001).

CONCLUSIONS

Both qualitative and quantitative analysis revealed that unaffected first-degree relatives have increased antibody response to microbial antigens. This impaired immunological response towards enteric microorganisms may result from a genetic predisposition.

Serological markers of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a heterogeneous group of chronic inflammatory disorders of the gastrointestinal tract with two main distinguishable entities, Crohn’s disease (CD) and ulcerative colitis (UC). IBD-unclassified (IBD-U) is a diagnosis that covers the “grey” zone of diagnostic uncertainty between UC and CD. Current diagnosis of IBD relies on the clinical, endoscopic, radiological, histological and biochemical features, but this approach has shortcomings especially in cases of overlapping symptoms of CD and UC. The need for a diagnostic tool that would improve the conventional methods in IBD diagnosis directed the search towards potential immunological markers, since an aberrant immune response against microbial or endogenous antigens in a genetically susceptible host seems to be implicated in IBD pathogenesis. The spectrum of antibodies to different microbial antigens and autoantibodies associated with IBD is rapidly expanding. Most of these antibodies are associated with CD like anti-glycan antibodies: anti-Saccharomices cerevisiae (ASCA) and the recently described anti-laminaribioside (ALCA), anti-chitobioside (ACCA), anti-mannobioside (AMCA), anti-laminarin (anti-L) and anti-chitin (anti-C) antibodies; in addition to other antibodies that target microbial antigens: anti-outer membrane porin C (anti-OmpC), anti-Cbir1 flagellin and anti-I2 antibody. Also, autoantibodies targeting the exocrine pancreas (PAB) were shown to be highly specific for CD. In contrast, UC has been associated with anti-neutrophil cytoplasmic autoantibodies (pANCA) and antibodies against goblet cells (GAB). Current evidence suggests that serologic panels of multiple antibodies are useful in differential diagnosis of CD versus UC and can be a valuable aid in stratifying patients according to disease phenotype and risk of complications.

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.

Variants of NOD1 and NOD2 genes display opposite associations with familial risk of Crohn's disease and anti-saccharomyces cerevisiae antibody levels

BACKGROUND

NOD2 is involved in Crohn's disease (CD), but the role of NOD1 remains unclear. Anti-Saccharomyces cerevisiae antibodies (ASCA) are higher in CD patients and some of their relatives. Using family-based analyses we investigated the relationships between NOD2 mutations, NOD1 +32656 variant, and both the risk of CD and ASCA levels. We compared allelic frequencies between families with multiple CD cases (multiplex), those with one case of CD (simplex), and control families, searching for a gradient of at risk alleles according to the prevalence of the disease among families.

METHODS

In all, 93 CD patients, 160 healthy relatives from 22 multiplex families, 22 CD patients and 81 healthy relatives from 22 simplex families, and 169 subjects from 27 control families were included in the study. ASCA levels were determined by enzyme-linked immunosorbent assay. NOD1 +32656, NOD2 R702W, G908R, and 1007fs were genotyped by polymerase chain reaction / restriction fragment length polymorphism.

RESULTS

In family-based analyses NOD2 mutations and the NOD1 wildtype allele were associated with CD in multiplex families, with a synergetic effect when risk alleles of both genes were transmitted. Lower ASCA levels were strongly associated with the NOD1 variant allele. Simplex families had a lower frequency of the "at risk" +32656 allele than multiplex families.

CONCLUSIONS

The +32656 variant was associated with low ASCA level and low risk of CD in multiplex families. NOD2 and NOD1 variants displayed antagonist effects on the risk of CD and ASCA level. A gradient of NOD1, NOD2 at-risk alleles was associated with the variable prevalence of CD in families.

Familial aggregation in inflammatory bowel disease: Is it genes or environment?

Inflammatory bowel disease (IBD) develops in genetically susceptible individuals due to the influence of environmental factors, leading to an abnormal recognition of microbiota antigens by the innate immune system which triggers an exaggerated immune response and subsequent bowel tissue damage. IBD has been more frequently found in families, an observation that could be due to either genetic, environmental or both types of factors present in these families. In addition to expanding our knowledge on IBD pathogenesis, defining the specific contribution to familial IBD of each one of these factors might have also clinical usefulness. We review the available evidence on familial IBD pathogenesis.

Current and future role of biomarkers in Crohn's disease risk assessment and treatment

BACKGROUND

Crohn's disease (CD), a chronic inflammatory bowel disease (IBD), occurs in genetically susceptible individuals who develop aberrant immune responses to endoluminal bacteria. Recurrent inflammation increases the risk of several complications. Despite use of a traditional "step-up" therapy with corticosteroids and immunomodulators, most CD patients eventually require surgery at some time in their disease course. Newer biologic agents have been remarkably effective in controlling severe disease. Thus, "top-down," early aggressive therapy has been proposed to yield better outcomes, especially in complicated disease. However, safety and cost issues mandate the need for careful patient selection. Identification of high-risk candidates who may benefit from aggressive therapy is becoming increasingly relevant. Serologic and genetic markers of CD have great potential in this regard. The aim of this review is to highlight the clinical relevance of these markers for diagnostics and prognostication.

METHODS

A current PubMed literature search identified articles regarding the role of biomarkers in IBD diagnosis, severity prediction, and stratification. Studies were also reviewed on the presence of IBD markers in non-IBD diseases.

RESULTS

Several IBD seromarkers and genetic markers appear to be associated with complex CD phenotypes. Qualitative and quantitative serum immune reactivity to microbial antigens may be predictive of disease progression and complications.

CONCLUSION

The cumulative evidence provided by serologic and genetic testing has the potential to enhance clinical decision-making when formulating individualized IBD therapeutic plans.

Antiglycan antibodies in Greek patients with inflammatory bowel disease

BACKGROUND

Antiglycan antibodies have recently been reported to be associated with Crohn's disease (CD). These antibodies include anti-Saccharomyces cerevisiae mannan antibodies (ASCA), anti-laminariobioside carbohydrate antibodies (ALCA), anti-chitobioside carbohydrate antibodies (ACCA), and anti-mannobioside carbohydrate antibodies (AMCA).

AIMS

The aim of this study was to evaluate their diagnostic accuracy in Greek patients with inflammatory bowel disease (IBD).

METHODS

Serum was collected from 191 patients with IBD (85 with ulcerative colitis (UC) and 106 with CD), 29 cases with other causes of intestinal inflammation and 96 healthy controls. Antiglycan antibodies were measured using commercially available enzyme immunoassays.

RESULTS

Higher levels of antiglycan antibodies were detected in patients with CD compared to patients with UC and controls. Although all types of antiglycan antibodies had a high specificity for diagnosing CD, their sensitivity was rather low, with best results obtained with ASCA and ALCA (41.5 and 52.8%, respectively). Increased levels of ASCA and ALCA were associated with stricturing and penetrating disease phenotype, and the need for surgery (p < 0.05).

CONCLUSIONS

Antiglycan antibodies in Greek IBD patients are significantly associated with CD, and especially to phenotypes of complicated disease, with ASCA and ALCA exhibiting the highest sensitivity.

Serologic antiglycan antibodies in inflammatory bowel disease

At diagnosis, the clinical presentation of both entities of inflammatory bowel disease (IBD), Crohn's disease (CD) and ulcerative colitis (UC), can be highly heterogeneous, leading to a delay in correct identification or differentiation between CD and UC in a subgroup of patients. In addition, the natural history of IBD patients is strikingly variable. During the life of a CD patient, in the majority of instances, stricturing or perforating complications occur, leading to surgery. Serologic antiglycan antibodies directed against various microbial carbohydrate epitopes are useful in differentiation of CD vs. UC and are a promising tool for identification of CD patients at risk for rapid progression and need for surgical intervention. Instruments for prediction of CD behavior are critical, as the use of immunomodulators and/or biologicals early in the disease course might be justified for patients with a high hazard for complicated disease behavior.

Noninvasive methods in evaluation of inflammatory bowel disease: where do we stand now? An update

The inflammatory bowel diseases, consisting of Crohn's disease, ulcerative colitis and indeterminate colitis, are distinguished by idiopathic and chronic inflammation of the digestive tract. The distinction between inflammatory bowel diseases and functional bowel disorders, such as irritable bowel syndrome, can be complex because they often present with similar symptoms. Rapid and inexpensive noninvasive tests that are sensitive, specific and simple are needed to prevent patient discomfort, delay in diagnosis, and unnecessary costs. None of the current commercially available serological biomarker tests can be used as a stand-alone diagnostic in clinics. Instead, these are used as an adjunct to endoscopy in diagnosis and prognosis of the disease. Along these lines,, fecal lactoferrin and calprotectin tests seem to be one step further from other tests with larger number of studies, higher sensitivity and specificity and wider availability.