Segregation of pANCA antigenic recognition by DNase treatment of neutrophils: ulcerative colitis, type 1 autoimmune hepatitis, and primary sclerosing cholangitis

Detection by flow cytometry of anti-neutrophil cytoplasmic antibodies in a novel approach based on neutrophil extracellular traps

BACKGROUND

Anti-neutrophil-cytoplasmic antibodies (ANCA) are auto-antibodies directed against components of neutrophil granulocytes and may be found in various inflammatory conditions, like small-vessel vasculitis or ulcerative colitis (UC). Routine ANCA screening is performed on ethanol-fixed neutrophils using indirect immunofluorescence technique. Yet, how neutrophil granule proteins become available to immunologic presentation is a matter of debate. In recent years, various studies have shown that neutrophils are able to extrude their chromatin decorated with granular proteins as neutrophil extracelullar traps (NETs).

AIM

We hypothesized that (I) ANCA immunoreactivity may be found on NETs and (II) NETs may serve as a useful tool in a novel approach for ANCA detection.

METHODS

Sera from patients suffering from either ANCA-associated vasculitis (n = 10), UC (n = 30) or sera from patients without diagnosed ANCA-associated diseases (n = 20), respectively, were subjected to indirect immunofluorescence and a newly developed method to detect ANCA by flow cytometry employing microbead technology.

RESULTS

ANCA-related immunofluorescence was readily detectable on ethanol-fixed NETs, establishing NETs as a structure carrying ANCA target antigens. Moreover, we observed that neutrophils form NETs in response to microbeads and stick to the surface of these beads. Using these NET-coated microbeads in flow cytometry, we were capable of reliably detecting p-ANCA, c-ANCA, and a-ANCA in tested patient sera. UC-related complex DNase-1-sensitive ANCA (NET-ANCA) antigens were also detected on NET-coated microbeads.

CONCLUSION

NET-coated microbeads may be commercially developed as a novel tool for automated ANCA screening assays using flow cytometry.

Serological markers and inflammatory bowel disease: Prevalence of serum markers and their diagnostic value in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic nonspecific disease of the digestive tract that is caused by genetic and environmental factors, including ulcerative colitis, Crohn's disease, and unclassified IBD. At present, the diagnosis of IBD depends mainly on clinical manifestations, imaging changes, colonoscopy, and pathological biopsy, but there exist some limitations. The advantages of serological markers in IBD diagnosis are prominent, and a large number of relevant studies have been reported. This paper reviews the diagnostic and therapeutic value of serological markers in IBD, with an aim to clarify their role in the diagnosis and treatment of IBD.

TNFRSF1B Is Associated with ANCA in IBD

The genetic basis of antineutrophil cytoplasmic antibody, an important biomarker of inflammatory bowel disease (IBD), has never been thoroughly examined on a genome-wide scale. In this study, we performed a 2-stage genome-wide association study (GWAS) on antineutrophil cytoplasmic antibody in IBD cases. In the 2959 IBD cases in the discovery stage, we observed an association between a variant in the gene TNFRSF1B with antineutrophil cytoplasmic antibody level (rs5745994, minor allele frequency = 0.028, beta = 18.12, 95% CI, 11.82-24.22, P = 1.89 × 10). This association was replicated in an independent cohort of 419 IBD cases (beta = 16.91, 95% CI, 6.13-27.69, P = 2.38 × 10). With a Q-value of 0.036, we performed a fixed-effect meta-analysis for the association of rs5745994 in both cohorts and observed a stronger association signal (beta = 17.81, 95% CI, 12.36-23.25, P = 8.97 × 10). TNFRSF1B gene codes for tumor necrosis factor (TNF) receptor 2 (TNFR2), thereby we examined the reported TNFRSF1B variant with serum TNFR2 level. We observed a negative association with serum TNFR2 level being 8.23 EU/mL in carriers and 9.12 EU/mL in noncarriers (P = 0.033). This finding indicates the functional role of identified TNFRSF1B variant in IBD serology and may be reflective of the underlying biological mechanisms that determine clinical expression and/or response to certain therapies.

Biomarkers of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic disease mostly involved with intestine with unknown etiology. Diagnosis, evaluation of severity, and prognosis are still present as challenges for physicians. An ideal biomarker with the characters such as simple, easy to perform, noninvasive or microinvasive, cheap, rapid, and reproducible is helpful for patients and clinicians. Currently biomarkers applied in clinic include CRP, ESR, pANCA, ASCA, and fecal calprotectin. However, they are far from ideal. Lots of studies are focused on seeking for ideal biomarker for IBD. Herein, the paper reviewed recent researches on biomarkers of IBD to get advances of biomarkers in inflammatory bowel disease.

Diagnostic value of distinguishing and reporting different perinuclear ANCA (P-ANCA) immunofluorescence patterns: a prospective study

OBJECTIVES

To investigate whether discriminating the classic perinuclear antineutrophil cytoplasmic antibody (P-ANCA) pattern from atypical P-ANCA and uninterpretable patterns improves the diagnostic utility of ANCA testing.

METHODS

All ANCA requests (n = 3,544) referred to Pathology Queensland were analyzed prospectively over 4 months for P-ANCA pattern subtypes and myeloperoxidase (MPO)-ANCA/PR3-ANCA results and correlated with clinical, laboratory, and radiologic evidence of necrotizing small vessel vasculitis.

RESULTS

Of the 436 perinuclear immunofluorescence-positive samples, 45 were classic P-ANCA, 163 were atypical P-ANCA, and 228 were antinuclear antibodies/uninterpretable. The classic P-ANCA pattern had a significantly stronger association with vasculitis (30/45) than atypical P-ANCA (2/163) (P <.0001) or ANA/uninterpretable patterns (8/228) (P <.0001). The combination of a classic P-ANCA pattern and positive MPO-ANCA/PR3-ANCA result was also more strongly associated with vasculitis than a positive MPO-ANCA/PR3-ANCA result in isolation (P = .003).

CONCLUSIONS

This study demonstrates that reporting different P-ANCA patterns (including ANA/uninterpretable patterns) provides additional diagnostic information to MPO-ANCA/PR3-ANCA results.

Combined serological, genetic, and inflammatory markers differentiate non-IBD, Crohn's disease, and ulcerative colitis patients

BACKGROUND

Previous studies have demonstrated that serological markers can assist in diagnosing inflammatory bowel disease (IBD). In this study, we aim to build a diagnostic tool incorporating serological markers, genetic variants, and markers of inflammation into a computational algorithm to examine patterns of combinations of markers to (1) identify patients with IBD and (2) differentiate patients with Crohn's disease (CD) from ulcerative colitis (UC).

METHODS

In this cross-sectional study, patient blood samples from 572 CD, 328 UC, 437 non-IBD controls, and 183 healthy controls from academic and community centers were analyzed for 17 markers: 8 serological markers (ASCA-IgA, ASCA-IgG, ANCA, pANCA, OmpC, CBir1, A4-Fla2, and FlaX), 4 genetic markers (ATG16L1, NKX2-3, ECM1, and STAT3), and 5 inflammatory markers (CRP, SAA, ICAM-1, VCAM-1, and VEGF). A diagnostic Random Forest algorithm was constructed to classify IBD, CD, and UC.

RESULTS

Receiver operating characteristic analysis compared the diagnostic accuracy of using a panel of serological markers only (ASCA-IgA, ASCA-IgG, ANCA, pANCA, OmpC, and CBir1) versus using a marker panel that in addition to the serological markers mentioned above also included gene variants, inflammatory markers, and 2 additional serological markers (A4-Fla2 and FlaX). The extended marker panel increased the IBD versus non-IBD discrimination area under the curve from 0.80 (95% confidence interval [CI], ±0.05) to 0.87 (95% CI, ±0.04; P < 0.001). The CD versus UC discrimination increased from 0.78 (95% CI, ±0.06) to 0.93 (95% CI, ±0.04; P < 0.001).

CONCLUSIONS

Incorporating a combination of serological, genetic, and inflammation markers into a diagnostic algorithm improved the accuracy of identifying IBD and differentiating CD from UC versus using serological markers alone.

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.

The role of autoantibodies in inflammatory bowel disease

The search for the underlying trigger of an inappropriate inflammatory reaction characteristic of inflammatory bowel diseases (IBD) has led to the discovery of several antibodies. The panel of serologic markers for IBD is rapidly expanding. Serologic markers hold the promise of helping researchers and clinicians to better understand IBD heterogeneity and natural history. The real importance of the antibodies produced against various microbial and autoantigens is still uncertain. Whether these antibodies play a primary role in the pathogenesis of IBD, or their presence is only a consequence of the inflamed mucosa is a fundamental question that remains to be clarified. The impact of the routine evaluation of these serologic markers in the everyday clinical IBD diagnostic algorithm is questionable due to their limited sensitivity. Despite their great potential, the routine use of serologic markers for diagnosis and follow-up is currently not justified. However, their correlation with disease phenotype and behavior is more established. A combination of serum markers has been shown to be of more value compared to using single markers alone. The ongoing challenge is how to best utilize these serologic markers to provide clinically relevant information in a cost-effective manner. Further prospective clinical trials are needed to determine their exact role in pathogenesis and practical clinical importance. We review the current standpoint of the clinical impact of various established and newly suggested markers in Crohn's disease and ulcerative colitis.

The promise and pitfalls of serologic testing in inflammatory bowel disease

The role of IBD serologies is still evolving. However, as that evolution progresses, it will continue to provide important insights into the etiology of IBD and help define individualized treatment strategies for patients. The presence of multiple IBD antimicrobial antibodies and increased reactivity form a useful heuristic model to understand the evolution of CD. The role of ANCAs and autoantibodies in pathogenesis of UC is an area that requires further investigation. Although IBD serologies exhibit considerable diagnostic accuracy, it is unclear whether they will supplant simpler and more direct evaluations in making an initial diagnosis of UC or Crohn (Table 3). The utility of panels of IBD serologies to stratify and predict the course of CD has been an arena of fertile investigation. Developing individual treatment strategies based on the probability of developing complicated aggressive disease would be a significant advance in medical management of CD. However, if major clinical decisions are to be made based on these serologies, we will need more prospective critical studies from the time of diagnosis to define their clinical applicability and to demonstrate a true difference in outcomes.

Combination of genetic and quantitative serological immune markers are associated with complicated Crohn's disease behavior

BACKGROUND

Treatment of Crohn's disease (CD) with biologics may alter disease progression, leading to fewer disease-related complications, but cost and adverse event profiles often limit their effective use. Tools identifying patients at high risk of complications, who would benefit the most from biologics, would be valuable. Previous studies suggest that biomarkers may aid in determining the course of CD. We aimed to determine if combined serologic immune responses and NOD2 genetic markers are associated with CD complications.

METHODS

In this cross-sectional study, banked blood from well-characterized CD patients (n = 593; mean follow-up: 12 years) from tertiary and community centers was analyzed for six serological biomarkers (ASCA-IgA, ASCA-IgG, anti-OmpC, anti-CBir1, anti-I2, pANCA). In a patient subset (n = 385), NOD2 (SNP8, SNP12, SNP13) genotyping was performed. Complications included stricturing and penetrating disease behaviors. A logistic regression model for the risk of complications over time was constructed and evaluated by cross-validation.

RESULTS

For each serologic marker, complication rates were stratified by quartile. Complication frequency was significantly different across quartiles for each marker (P trend ≤ 0.001). Patients with SNP13 NOD2 risk alleles experienced increased complications versus patients without NOD2 mutations (P ≤ 0.001). A calibration plot of modeled versus observed complication rates demonstrated good agreement (R = 0.973). Performance of the model integrating serologic and genetic markers was demonstrated by area under the receiver operating characteristic curve (AUC = 0.801; 95% confidence interval: 0.757-0.846).

CONCLUSIONS

This model combining serologic and NOD2 genetic markers may provide physicians with a tool to assess the probability of patients developing a complication over the course of CD.

Serologic and laboratory markers in prediction of the disease course in inflammatory bowel disease

The search for biologic markers that can assess the natural history and perhaps predict the course of individual's disease including response to treatments over time has become an important focus of inflammatory bowel disease research. The knowledge of an individual's prognosis can help physicians and patients make important management decisions and aid communication on risk and benefits of disease and treatment.

Novel diagnostic and prognostic modalities in inflammatory bowel disease

Inflammatory bowel disease remains a complex disease with variable clinical presentations and often nonspecific symptoms. Physicians must rely on diagnostic tools for clarification of disease diagnosis and for guiding management of patients with established disease. Advances in radiologic imaging modalities facilitate early and accurate detection of luminal disease and extraluminal complications. The introduction and dissemination of small bowel capsule endoscopy and double-balloon enteroscopy permit detailed visualization and sampling of the mucosa throughout the entire bowel. Serologic biomarkers are evolving as a valuable tool to clarify diagnosis and stratify patients by disease phenotypes and patterns of behavior. Neutrophil-derived fecal biomarkers are emerging as useful surrogate markers of intestinal inflammation with the potential for a variety of clinical applications, but their application to clinical management has not yet been clarified.

Novel diagnostic and prognostic modalities in inflammatory bowel disease

Inflammatory bowel disease remains a complex disease with variable clinical presentations and often nonspecific symptoms. Physicians must rely on diagnostic tools for clarification of disease diagnosis and for guiding management of patients with established disease. Advances in radiologic imaging modalities facilitate early and accurate detection of luminal disease and extraluminal complications. The introduction and dissemination of small bowel capsule endoscopy and double-balloon enteroscopy permit detailed visualization and sampling of the mucosa throughout the entire bowel. Serologic biomarkers are evolving as a valuable tool to clarify diagnosis and stratify patients by disease phenotypes and patterns of behavior. Neutrophil-derived fecal biomarkers are emerging as useful surrogate markers of intestinal inflammation with the potential for a variety of clinical applications, but their application to clinical management has not yet been clarified.

DNA-bound lactoferrin is the major target for antineutrophil perinuclear cytoplasmic antibodies in ulcerative colitis

Lactoferrin has repeatedly been proposed to be a target for antineutrophil perinuclear cytoplasmic antibodies (P-ANCA), which are present in 67% of ulcerative colitis (UC) cases. However, this high prevalence has not been achieved with either Western blots or monospecific ELISA on the basis of purified lactoferrin bound to the solid phase. We reevaluated autoantibodies against lactoferrin by indirect immunofluorescence (IIF), using a lactoferrin-tuned granulocyte substrate. Slides with ethanol-fixed human granulocytes were stripped of their P-ANCA targets by high-salt treatment and then reconstituted with human lactoferrin (LFR granulocytes). The slides were then subjected to IIF with a panel of sera (39 UC, 10 antimyeloperoxidase-positive vasculitis, 50 healthy blood donors). The human sera were also analyzed with antilactoferrin ELISA. In 28 of 39 (71.8%) sera from UC patients, antibodies could be determined that bound exclusively to LFR granulocytes. Nuclease-treated cells failed to show this reactivity. ELISA detected antilactoferrin antibodies in only two UC sera. Lactoferrin is a major P-ANCA target in UC but requires DNA to present the epitopes relevant for the reaction with the autoantibodies. Antigen-stripped and lactoferrin-reconstituted granulocytes can be used in IIF to diagnose antilactoferrin antibodies in UC more reliably than with existing ELISA systems.

Use of serum biomarkers in a diagnostic test for irritable bowel syndrome

BACKGROUND

Currently, no single serum biomarker can reliably differentiate irritable bowel syndrome (IBS) from other functional gastrointestinal disorders or organic diseases of the gastrointestinal tract.

AIM

To develop and validate a diagnostic test using serum biomarkers to detect IBS.

METHODS

Ten serum biomarkers were selected from a potential panel of 140 for their ability to differentiate IBS from non-IBS disease in blood samples from patients with IBS, other gastrointestinal disorders and healthy volunteers. A predictive modelling tool was developed to assess patterns and relationships among the 10 serum biomarkers that best differentiated IBS patients from healthy controls and patients with non-IBS gastrointestinal disease. This model was tested in a different cohort of patients and healthy controls (n = 516) to determine the predictive accuracy of differentiating IBS from non-IBS.

RESULTS

The sensitivity and specificity of the 10-biomarker algorithm for differentiating IBS from non-IBS was 50% and 88% respectively. The positive predictive value was 81%, and the negative predictive value was 64% at 50% IBS prevalence in the validation cohort. Overall accuracy was 70%.

CONCLUSIONS

Assessing serum biomarker patterns can differentiate IBS from non-IBS with reasonable sensitivity and specificity. Assessing serum biomarkers in an overall diagnostic strategy may allow earlier diagnosis and treatment for patients with IBS.

Multiparameter analysis of immunogenetic mechanisms in clinical diagnosis and management of inflammatory bowel disease

The integrity of the intestinal mucosa depends on a functional coordination of the epithelium, lumenal microorganisms, and the local immune system. The mammalian immune system is superbly organized for innate and adaptive recognition of microbial antigens, a defensive capacity that must be balanced against the tissue damage produced by immune activity to preserve normal intestinal function. Inflammatory bowel disease (IBD) is generally thought to reflect an impairment in this balance, due to a combination of host genetic traits that shift the balance of immune and epithelial function to commensal microbiota, and perhaps the composition or activity of certain microbial elements as well. There has been much progress defining the fundamental disorders of these host traits, immunologic processes, and microbial targets in inflammatory bowel disease. Other fields of clinical and geologic microbiology are teaching us about the dynamic interaction of commensal bacteria with their host environment. These lines of investigation have revealed not only important insights about inflammatory bowel disease (IBD) pathogenesis, but also defined technologies and tools useful for its diagnosis and clinical management. This review focuses on these advances at the translational interface. We will first consider the innate anti-microbial response, centering on the utility of NOD2 genotyping for predicting disease susceptibility, prognosis, and therapeutic response profile. We will then turn to the adaptive anti-microbial response, focusing on the application of antibodies to fungal and bacterial species and products for Crohn's disease (CD) diagnosis and prognosis, and immunogenetics of T cell immunosuppression management. Finally, we will describe autoimmune mechanisms in IBD, with particular attention to autoantibodies in IBD diagnosis and infliximab responsiveness. We will conclude with the concept of multiparameter analysis of patients, to refine patient characterization and stratification in diagnosis and clinical management.

What is the role of serological markers in the diagnosis of IBD?

Research and technological advancements have fostered a novel approach to understanding the intricate relationship between genetic and clinical expression of disease. Both genetic and serum antibody markers hold the most promise in helping researchers better comprehend disease heterogeneity and natural history. Although our current gold standard diagnostic tests do not possess this capability, exciting preliminary research suggests IBD-specific antibody markers may serve as predictors of an individual's disease course. Thus, the foundation has been laid upon which the discovery of novel IBD-specific and IBD-sensitive markers will enable researchers to identify at-risk individuals, as well as diagnose IBD and stratify patients into homogeneous subtypes with certainty. Clinicians can then create and implement individual treatment plans designed to improve the long-term prognosis of these chronic diseases.

Abnormal mucosal immune response to altered bacterial flora following restorative proctocolectomy in patients with ulcerative colitis: serologic measures, immunogenetics, and clinical correlations

A patient from the University of North Carolina Hospitals is presented who developed Crohn's disease of the ileal J-pouch following restorative proctocolectomy for ulcerative colitis. Inflammation of the ileal pouch in human inflammatory bowel disease (IBD) represents the best clinical example of the importance of host-enteric microbial interactions, and this case highlights rapid advances in our understanding of the role of the enteric microbiota in the immunopathogenesis of IBD, impacting on clinical care. Successful management of this patient necessitated accurate diagnosis as there are several inflammatory and non-inflammatory conditions of the pouch that present with similar symptoms. Diagnostic measures included serologic assays of response to microbial antigens, including ASCA, anti-OmpC, anti-Cbir1, and pANCA with DNAse sensitivity. Although the serologic detection of selective loss of tolerance to microbial antigens defines clinically important subgroups of inflammatory bowel disease patients, the clinical value of these serodiagnostic tests is a matter of debate. Genome wide screens have also identified NOD2/CARD15, IL23 receptor, and ATG16L1 variants as important in IBD susceptibility and pathogenesis. These genetic associations have also provided new insights into the importance of interaction between the host and microbes in the pathogenesis of IBD, but the precise mechanisms by which these gene variants contribute to disease development remain to be determined. Genetic associations and serological markers will ultimately be used to define important clinical subgroups of disease, predict natural history, and ultimately identify patient populations for early therapeutic intervention.

[Relevance of serologic studies in inflammatory bowel diseases]

The panel of serologic markers for inflammatory bowel diseases (IBDs) is rapidly expanding. Although anti- Saccharomyces cerevisiae antibodies (ASCA) and atypical perinuclear antineutrophil cytoplasmic antibodies (atypical P-ANCA) remain the most widely investigated, an increasing amount of experimental data is available on newly discovered antibodies directed against various microbial antigens. Such antibodies include anti-OmpC (outer membrane porin C), anti- Pseudomonas fluorescens (anti-I2) and antiglycan antibodies (anti-laminaribioside carbohydrate antibody [ALCA]), anti-chitobioside carbohydrate antibody [ACCA]), anti-mannobioside carbohydrate antibody [AMCA]) and anti-CBir1; this latter is the first bacterial antigen to induce colitis in animal models of IBD and also leads to a pathological immune response in IBD patients (anti-flagellin antibody). The role of assessment of various antibodies in the current diagnostic algorithm of IBD is rather questionable due to their limited sensitivity. In contrast, the association of serologic markers with disease behavior and phenotype is getting more into the focus of interest. An increasing number of observations confirm that patients with Crohn's disease expressing multiple serologic markers at high titers are more likely to have complicated small bowel disease (e.g. stricture and/or perforation) and are at higher risk for surgery than those without, or with low titer of antibodies. Creating homogenous disease sub-groups based on serologic response may help develop more standardized therapeutic approaches and may help in a better understanding of the pathomechanism of IBD. Further prospective clinical studies are needed to establish the clinical role of serologic tests in IBD.

Utility of serological markers in inflammatory bowel diseases: Gadget or magic?

The panel of serologic markers for inflammatory bowel diseases (IBD) is rapidly expanding. Although anti-Saccharomyces cerevisiae antibodies (ASCA) and atypical perinuclear antineutrophil cytoplasmic antibodies (P-ANCA) remain the most widely investigated, an increasing amount of experimental data is available on newly discovered antibodies directed against various microbial antigens. The role of the assessment of various antibodies in the current IBD diagnostic algorithm is often questionable due to their limited sensitivity. In contrast, the association of serologic markers with disease behavior and phenotype is becoming increasingly well-established. An increasing number of observations confirms that patients with Crohn’s disease expressing multiple serologic markers at high titers are more likely to have complicated small bowel disease (e.g. stricture and/or perforation) and are at higher risk for surgery than those without, or with low titers of antibodies. Creating homogenous disease sub-groups based on serologic response may help develop more standardized therapeutic approaches and may help in a better understanding of the pathomechanism of IBD. Further prospective clinical studies are needed to establish the clinical role of serologic tests in IBD.

Association of IL-10 and TNFalpha genotypes with ANCA appearance in ulcerative colitis

The appearance of autoantibodies is a common characteristic of ulcerative colitis (UC). Specifically, anti-neutrophil cytoplasmic antibodies (ANCA) are the most prevalent in this disease and their synthesis may be genetically conditioned. The aim of the present study was to test the influence on appearance of autoantibodies of IL-10 and TNFalpha genes promoter polymorphisms, which control cytokine levels. Genetic polymorphisms of TNFalpha (-308 G/A) and IL-10 (-1082 G/A) and ANCA and anti-goblet cells antibodies (GAB) presence were determined in 99 UC patients. The -308A* allele and -308AA/AGTNFalpha genotypes (high producer), clearly correlated with ANCA positivity (p = 0.004 and p = 0.007, respectively). Additionally, homozygous carriage of the -1082A*IL-10 allele (low producer) significantly associated with ANCA presence (p = 0.007). Furthermore, combination of both genotypes (low IL-10/high TNFalpha producer genotype) had a greater influence on ANCA positivity than each individual genotype (p = 0.008). ANCA production in UC thus appears to be conditioned by IL-10 and TNFalpha genotypes.

Diagnostic precision of anti-Saccharomyces cerevisiae antibodies and perinuclear antineutrophil cytoplasmic antibodies in inflammatory bowel disease

AIMS

The aim of this study was to assess the diagnostic precision of antiSaccharomyces cerevisiae (ASCA) and perinuclear antineutrophil cytoplasmic antibodies (pANCA) in inflammatory bowel disease (IBD) and evaluate their discriminative ability between ulcerative colitis (UC) and Crohn's disease (CD).

METHODS

Meta-analysis of studies reporting on ASCA and pANCA in IBD was performed. Sensitivity, specificity, and likelihood ratios (LR+, LR-) were calculated for different test combinations for CD, UC, and for IBD compared with controls. Meta-regression was used to analyze the effect of age, DNAse, colonic CD, and assay type.

RESULTS

Sixty studies comprising 3,841 UC and 4,019 CD patients were included. The ASCA+ with pANCA- test offered the best sensitivity for CD (54.6%) with 92.8% specificity and an area under the ROC (receiver operating characteristic) curve (AUC) of 0.85 (LR+ = 6.5, LR- = 0.5). Sensitivity and specificity of pANCA+ tests for UC were 55.3% and 88.5%, respectively (AUC of 0.82; LR+ = 4.5, LR- = 0.5). Sensitivity and specificity were improved to 70.3% and 93.4% in a pediatric subgroup when combined with an ASCA- test. Meta-regression analysis showed decreased diagnostic precision of ASCA for isolated colonic CD (RDOR = 0.3).

CONCLUSIONS

ASCA and pANCA testing are specific but not sensitive for CD and UC. It may be particularly useful for differentiating between CD and UC in the pediatric population.

Analysis of serum antibodies in patients suspected of having inflammatory bowel disease

Inflammatory bowel disease (IBD) is the general term used for a heterogeneous group of intestinal disorders, including Crohn's disease (CD) and ulcerative colitis (UC). Serological markers such as anti-Saccharomyces cerevisiae antibodies (ASCA) and atypical perinuclear antineutrophilic cytoplasmic antibody (atypical pANCA) have proven useful in the diagnosis and differentiation of CD and UC. Immunoglobulin A (IgA) antibody directed against the outer membrane protein C (OmpC) of Escherichia coli is said by one group to have clinical utility in diagnosing IBD, specifically in ASCA-negative CD patients. Our objective in this study was to compare the results obtained from two separate laboratories offering similar IBD tests using sera from suspected IBD patients. One hundred ninety-seven sera received for IBD testing were included in the study. The agreement between the two laboratories was 93.4% for ASCA IgA, 90.9% for ASCA IgG, and 87.8% for atypical pANCA IgG. There were 25 sera with ASCA-negative/OmpC-positive results reported by one laboratory. Thirteen of these 25 (52.0%) ASCA-negative/OmpC-positive sera were also atypical pANCA positive (9 as determined by both laboratories, 3 by one, and 1 by the other). Atypical pANCA antibody is found primarily in IBD patients with UC and colon-limited CD (Crohn's colitis). We conclude that the ASCA and atypical pANCA assays showed good agreement between the two laboratories, but the data for ASCA-negative/OmpC-positive sera suggest that many (52.0%) of these patients were more likely to have had UC or Crohn's colitis based on the presence of an atypical pANCA.

Anti-Saccharomyces cerevisiae antibodies are associated with the development of postoperative fistulas following ileal pouch-anal anastomosis

Although serologic testing for perinuclear antineutrophil cytoplasmic antibodies (pANCA) and anti-Saccharomyces cerevisiae antibodies (ASCA) is reportedly useful in distinguishing ulcerative colitis (UC) from Crohn's disease (CD), there are few and conflicting reports assessing their utility in predicting postoperative complications after ileal pouch-anal anastomosis (IPAA). We examined the associations between postoperative complications such as pouchitis or fistulas and pANCA and ASCA antibodies in a group of patients who underwent IPAA for UC. We conducted a retrospective chart review of 34 patients initially diagnosed with UC (four of these patients had a diagnosis of indeterminate colitis) who underwent IPAA by a single surgeon, and who had pANCA and ASCA antibody levels measured during their clinical course. Study patients were assigned to four groups based on the pattern of antibody reactivity: pANCA+/ASCA- (16 patients), pANCA-/ASCA+ (nine patients), pANCA+/ASCA+ (five patients), and pANCA-/ASCA- (four patients). The median length of follow-up was 16 months (3-144 months). None of the patients (0 of 16) who were pANCA+/ASCA- had their preoperative diagnosis of UC changed after a median follow-up of 14 months (3-118 months). Of the nine patients with a preoperative diagnosis of UC who were pANCA-/ASCA+, four patients (44%) had their diagnosis changed postoperatively to CD based on clinical findings, with a median follow-up: 15 months (5-98 months). Of 16 patients who underwent IPAA and who were pANCA+/ASCA-, 15 of 16 (93.75%), were free of fistulas postoperatively, with a median follow-up of 14 months (3-118 months). Of nine patients with a preoperative diagnosis of UC who underwent IPAA and who were pANCA-/ASCA+, four of nine (44%; p = 0.04) developed fistulas postoperatively, with a median length of follow-up of 55 months (15-67 months). No relationship between serologic profiles or antibody titer levels and the development of pouchitis was identified. In a cohort of patients undergoing IPAA for UC, serologic profiles may be useful in identifying patients at risk of postoperative fistula formation. Patients who were pANCA-/ASCA+ were at increased risk for the development of fistulas postoperatively compared to patients who were pANCA+/ASCA-, and were also more likely to have their diagnosis changed postoperatively to CD. A larger study is needed to validate these observations.

Immunogenetic phenotypes in inflammatory bowel disease

The currently accepted etiopathogenic hypothesis suggests that the chronic intestinal inflammation and related systemic manifestations characteristic of inflammatory bowel disease (IBD) are due to an overly aggressive or pathologic immune response to resident luminal bacterial constituents. Predisposing factors are genetic dysregulation of mucosal immune responses and/or barrier function, with onset triggered by environmental stimuli. These factors and their interactions may also be important determinants of disease phenotype and disease progression. The emergence of immunogenetic phenotypes lends support to the proposed hypothesis that susceptibility genes regulate distinct immune processes, driven by luminal antigens, expressed as specific immune phenotypes which in turn influence clinical phenotypes in IBD patients.

Comparison of a multiplex, bead-based fluorescent assay and immunofluorescence methods for the detection of ANA and ANCA autoantibodies in human serum

Detection of antinuclear (ANA) and antineutrophil cytoplasmic (ANCA) antibodies is extensively used for establishing a diagnosis in patients with clinical features suggestive of autoimmune disorders. The most common methods for the identification of positive patients' sera for ANA or ANCA are indirect immunofluorescence (IIF) and ELISA-based procedures. Considerable effort has been made in developing simpler automated assays for routine laboratory use. Recently a commercially available microsphere-based fluorescent assay has been introduced for the detection of ANA and ANCA. The aim of this study was to compare this technology with routinely used IIF and ELISA procedures, in patients with a suggested autoimmune disorder. A highly significant correlation between ELISA procedures for specific antibodies and the microsphere-based assays were obtained for both ANA and ANCA as well as for extractable nuclear antigens ELISA screening, indicating that multiplex technology could replace individual ELISA tests for the measurement of specific autoantibodies. However, a low sensitivity for identifying IIF-positive cases was obtained for both ANA (58.0%) and ANCA (59.1%), although there was a significant correlation between the assays. In conclusion, our data show that a microsphere-based fluorescent assay may be a valid platform for the simultaneous determination of circulating individual ANA and ANCA autoantibodies. Furthermore, multiplexing technology offers several advantages that will probably make it an attractive tool in the future. Nevertheless, until further studies are conducted that determine the clinical performance of the multiplex technology, the initial screening of patients for autoantibodies with IIF is still considered necessary.

Serologic markers in inflammatory bowel disease

Inflammatory bowel disease (IBD) is an enduring disease involving mostly young people, with symptoms of bloody diarrhea and abdominal cramps. Several antibodies have been associated with IBD, the 2 most comprehensively studied being autoantibodies to neutrophils (atypical perinuclear anti-neutrophil cytoplasmic antibodies) and anti-Saccharomyces cerevisiae antibodies. This review focuses on the value of these antibodies for diagnosing IBD, differentiating Crohn disease from ulcerative colitis, indeterminate colitis, monitoring disease, defining clinical phenotypes, predicting response to therapy, and as subclinical markers. Pancreatic antibodies and newly identified anti-microbial antibodies (anti-outer membrane porin C, anti-I2, and anti-flagellin) are also reviewed.

Defects in mucosal immunity leading to ulcerative colitis

Evidence accumulated over the last decade demonstrates that what we call 'ulcerative colitis' is actually a heterogeneous group of diseases resulting from different pathogenic mechanisms with a common symptomatic expression. Subgroups of patients with ulcerative colitis can be stratified by presence or absence of serum autoantibodies, which are thought not to be pathogenic but to mark for a distinct disease phenotype. In recent years, animal-based experimental systems have emerged that reflect human ulcerative colitis and have potential to accelerate our understanding of its pathogenesis. Genetic and immunological data from human studies in combination with results from animal model systems are the foundation of a hypothesis, which includes a role for microbial antigen exposure in the initiation, perpetuation, and amplification of the disease. In ulcerative colitis, it appears as though the T-cell response to the antigens is not T-helper (Th) 1 dominant as in the case of Crohn's disease but rather is either Th2 [interleukin (IL)-4, IL-13] or is mediated by specialized cells such as natural killer (NK) T cells (IL-13). Lamina propria T cells from ulcerative colitis patients produce significantly greater amounts of IL-13. Ulcerative colitis is associated with an atypical Th2 response mediated by a distinct subset of NK T cells that produce IL-13 and are cytotoxic for epithelial cells. The way in which this response affects the ultimate cascade of inflammatory events has yet to be determined.

What do antineutrophil cytoplasmic antibodies (ANCA) tell us?

Antineutrophil cytoplasmic antibodies (ANCA) are autoantibodies directed against antigens found in the cytoplasmic granules of neutrophils and monocytes. ANCA testing is usually performed to help diagnose or exclude Wegener's granulomatosis and microscopic polyangiitis. The three most commonly used assays are indirect immunofluorescence (IIF) and the direct and 'capture' enzyme-linked immunosorbent assays (ELISAs) for ANCA directed against proteinase 3 (PR3) and myeloperoxidase (MPO). Although the International Consensus Statement for Testing and Reporting ANCA recommends that all sera are screened for ANCA by IIF and that IIF-positivity is confirmed by direct ELISAs, some laboratories test by direct ELISA alone, others screen with direct ELISA and confirm positive sera by IIF, and a few use capture ELISAs. This chapter discusses the various forms of vasculitis associated with ANCA, the usefulness of each of the ANCA assays and how ANCA testing can be used in the management of patients with small-vessel vasculitis.

Biomarkers in inflammatory bowel disease

PURPOSE OF REVIEW

Inflammatory bowel disease is characterized by chronic intestinal inflammation in the absence of a recognized pathogen. In its classic description, there are two principal forms of inflammatory bowel disease: Crohn disease and ulcerative colitis. The clinical heterogeneity of these disorders alludes to the possibility of diverse pathogenetic mechanisms underlying inflammatory bowel diseases. The purpose of this review is to summarize the latest information on biomarkers of Crohn disease and ulcerative colitis.

RECENT FINDINGS

The authors have focused on serologic markers for which emerging data support their use as predictors of disease evolution. Serologic markers such as perinuclear antineutrophil cytoplasmic antibody, anti-Saccharomyces cerevisiae antibody, anti-OmpC, and anti-I2 may be useful in distinguishing inflammatory bowel diseases from functional disorders and ulcerative colitis from Crohn disease and predicting complications of disease. Genetic markers such as CARD15/NOD2 may be useful in the future when combined with other markers to predict disease course. Biochemical markers of inflammation such as C-reactive protein are useful to stratify patients likely to respond to biologic therapies and to follow response to treatment. In the future, functional genomics and proteomics will be used to rapidly screen patients for subclinical characteristics that can predict disease course and response to therapy.

SUMMARY

A variety of biomarkers can be used to stratify patients with inflammatory bowel disease into more homogeneous subgroups with respect to response to therapy and disease progression.

Are pANCA, ASCA, or cytokine gene polymorphisms associated with pouchitis? Long-term follow-up in 102 ulcerative colitis patients

OBJECTIVE

Pouchitis is the most frequent complication after ileal pouch-anal anastomosis for ulcerative colitis. This study aims to analyze the frequency and characteristics of pouchitis in long-term follow-up in a large population, and to determine whether a significant association exists between five immunogenetic markers and pouchitis.

METHODS

From a population of over 500 ulcerative colitis patients who had undergone ileal pouch-anal anastamosis 5-12 yr earlier, 102 subjects participated in the study. Using clinical data obtained from interviews and chart reviews, patients were classified into three groups: no pouchitis; 1-2 episodes per year; and >2 episodes per year. Coded sera from the patients were analyzed for ulcerative colitis-associated perinuclear antineutrophil cytoplasmic antibodies and Crohn's disease-associated anti-saccharomyces cerevesiae antibodies. Interleukin-1 receptor antagonist, tumor necrosis factor (TNF), and lymphotoxin beta (lymphotoxin) polymorphisms were also analyzed.

RESULTS

Pouchitis affected 49% of the study population. Antineutrophil cytoplasmic antibodies, anti-saccharomyces cerevesiae antibodies, and lymphotoxin-beta polymorphisms were not associated with pouchitis. Carriage of interleukin-1 receptor antagonist allele 2 was significantly greater among those without pouchitis than those with pouchitis. Patients without pouchitis had a significantly greater carriage rate of TNF allele 2.

CONCLUSIONS

Perinuclear antineutrophil cytoplasmic antibodies and anti-saccharomyces cerevesiae antibodies are not correlated with pouchitis, but interleukin-1 receptor antagonist and TNF may play a role in its development. Further evaluation of these markers in pouchitis will require larger populations, long-term prospective observation, and studies that correlate polymorphisms with specific immunologic functions.

Seroreactivity against Saccharomyces cerevisiae in patients with Crohn’s disease and celiac disease

AIM: To explore whether there was anti-Saccharomyces cerevisiae antibodies (ASCA) positivity in our patients with biopsy-confirmed celiac disease.

METHODS: A cohort of patients with inflammatory bowel diseases (42 patients with Crohn’s disease and 10 patients with ulcerative colitis) and gluten sensitive enteropathy (16 patients) from Debrecen, Hungary were enrolled in the study. The diagnosis was made using the formally accepted criteria. Perinuclear antineutrophil cytoplasmic antibodies (pANCA) and anti-Saccharomyces cerevisiae antibodies (ASCA), antiendomysium antibodies (EMA), antigliadin antibodies (AGA) and anti human tissue transglutaminase antibodies (tTGA) were investigated.

RESULTS: The results showed that ASCA positivity occurred not only in Crohn’s disease but also in Celiac disease and in these cases both the IgG and IgA type antibodies were proved.

CONCLUSION: It is conceivable that ASCA positivity correlates with the (auto-) immune inflammation of small intestines and it is a specific marker of Crohn’s disease.

Advances in clinical laboratory tests for inflammatory bowel disease

Inflammatory bowel disease (IBD) is a generic term that refers to Crohn's disease and chronic ulcerative colitis (UC). The CD and UC are considered to be distinct forms of IBD; but there is a subgroup of CD with a UC-like presentation. The genetic factors play a significant role in IBD. IBD is associated with a strong familial pattern. Recent studies support the hypothesis that IBD patients have a dysregulated immune response to endogenous bacteria in the gastrointestinal tract. The serologic responses seen in Crohn's disease include antibodies to Saccharomyces cerevisiae, mycobacteria, bacteroides and E. coli. The pANCA antibody seen in UC and CD has been demonstrated to react with epitopes of H1 histone, Bacteroides caccae (Ton-B linked outer membrane protein), Pseudomonas fluorescens-associated bacterial protein I-2, mycobacterial histone 1 homologue called Hup B. In recent years, several serologic markers have been found to be useful for the diagnosis and differentiation of CD and UC. These markers include the following antibodies: (a) pANCA, (b) ASCA, (c) anti-pancreatic antibody, (d) OmpC antibody and (e) I-2 antibody and antibodies to anaerobic coccoid rods. The application of a panel of markers with the use of an algorithm (i.e. IBD First Step) can identify specific subtypes of IBD that have different clinical courses and progression of the diseases. The serologic markers are useful for the diagnosis and management of CD and UC patients.

Serological markers in inflammatory bowel diseases

This chapter is an overview of the literature on serological markers of inflammatory bowel diseases (IBD), focusing on anti-neutrophil cytoplasm autoantibodies (ANCA) and anti- Saccharomyces cerevisiae mannan antibodies (ASCA). The methodology for ANCA and ASCA testing is first introduced. The value of these markers as diagnostic tools is then discussed. Other chapters are devoted to the potential role of ANCA and ASCA in disease monitoring, disease stratification and as subclinical markers in families. Finally reviewed are other antibodies recently tested in clinical trials such as pancreatic antibodies and antibodies directed against bacterial antigens. The role of these antibodies in the pathophysiology of IBD still needs to be assessed. We also need to identify the ASCA immunogen(s) eliciting the antibody response.

Selected loss of tolerance evidenced by Crohn's disease-associated immune responses to auto- and microbial antigens

BACKGROUND & AIMS

Previous studies in Crohn's disease suggest global loss of tolerance with sonicated bacteria preparations containing hundreds of antigens. Monoassociation studies show that a solitary bacterium can induce colitis in one animal model, whereas another is responsible in other models. Among patients with Crohn's disease, serum responses have been documented to microbial and autoantigens (antibodies to the Escherichia coli outer-membrane porin C and the Pseudomonas fluorescens-associated sequence I2, antisaccharomyces cerevisiae antibody (ASCA), and perinuclear antineutrophil cytoplasmic antibodies). Our aim was to determine whether there are heterogeneous responses to these specific antigens.

METHODS

Sera from 330 Crohn's patients were analyzed. Immunoglobulin A enzyme-linked immunosorbent assays to ASCA, outer-membrane porin C, or I2 and immunoglobulin G enzyme-linked immunosorbent assay to ASCA and ANCA determined the presence and level of antibodies. Perinuclear antineutrophil cytoplasmic antibodies were determined by immunofluorescence.

RESULTS

ASCA was detected in 56% of patients; 55% were seroreactive to outer-membrane porin C, 50% were seroreactive to I2, and 23% were perinuclear antineutrophil cytoplasmic antibody positive. Eighty-five percent responded to at least 1 antigen; only 4% responded to all 4. Among microbial antigens, 78% responded to at least 1, and 57% were double positive, but only 26% responded to all 3. The level of response was stable over time and with change in disease activity. Among patients with the same qualitative antigen-response profiles, quantitative response differed. Cluster analysis of these antibody responses yielded 4 groups: ASCA, outer-membrane porin C/I2, perinuclear antineutrophil cytoplasmic antibodies, or no/low response.

CONCLUSIONS

Rather than global loss of tolerance, there seem to be patient subsets with differing responses to selected microbial and autoantigens.

Role of serology and routine laboratory tests in childhood inflammatory bowel disease

INTRODUCTION

Serology is reported to be helpful in evaluating children for inflammatory bowel disease (IBD), and distinguishing chronic ulcerative colitis (CUC) from Crohn's disease (CD). The markers include perinuclear staining antineutrophil cytoplasmic antibody (pANCA) for CUC and anti-Saccharomyces cerevisiae antibody (ASCA) for CD. In the clinical setting, hemoglobin (Hgb) and erythrocyte sedimentation rate (ESR) are commonly performed for screening symptomatic children for IBD. We examined whether there was an additional benefit of serology in addition to specific symptoms and routine laboratory tests in screening for IBD.

METHOD

Medical record data was reviewed on children investigated for IBD from February 1999 to April 2001. Children were included if they had blood analyzed for pANCA and ASCA, Hgb, ESR, and colonoscopy as part of their assessment.

RESULTS

Of 177 cases reviewed, 51 were diagnosed with CUC, 39 with CD, and 26 other inflammatory conditions. Visible rectal bleeding was the most discriminating symptom (occurred in 60/90 cases of IBD and 5/61 without IBD). There was a significant difference between the proportion with CUC positive for pANCA (42/51) and those with abnormal Hgb and ESR (30/51) (p < 0.05), but not between children with CD who were ASCA positive (18/39) and those with abnormal Hgb and ESR (26/39) (p = 0.27). The sensitivity and specificity of combined pANCA and ASCA was 68% and 92%, respectively. For the combination of Hgb, ESR, and the presence of rectal bleeding the respective values were 86% and 67%. Serology combined with Hgb and ESR and rectal bleeding as independent factors significantly (p < 0.05) improved sensitivity (89%) but reduced specificity (60%). Screening with the combination of rectal bleeding, Hgb, and ESR identified 86% (77/90) patients with IBD prior to an endoscopic procedure. A further 3 of 90 (3.3%) screened positive with the addition of serology.

CONCLUSION

Serology tests have a high degree of specificity for IBD while routine laboratory test have a higher sensitivity. When serology is combined with rectal bleeding, Hgb, and ESR, the sensitivity of screening children for IBD is significantly improved. However the large majority of children with IBD can be identified with a clinical history and routine laboratory tests as needing an endoscopic procedure with little benefit of adding serology.

Suspected inflammatory bowel disease--the clinical and economic impact of competing diagnostic strategies

OBJECTIVES

The suspicion of IBD in patients presenting with nonspecific abdominal pain and diarrhea results in the extensive use of invasive diagnostic testing in patients likely to have a functional GI disorder. Noninvasive serodiagnostic tests, however, accurately identify IBD and may serve as effective screening tools. The objective of this study was to examine the cost-effectiveness of initial serodiagnostic screening followed by standard invasive testing, compared to standard invasive testing alone, in patients presenting with uninvestigated symptoms suggestive of IBD.

METHODS

Decision analysis was performed to compare the costs and outcomes of competing diagnostic strategies. Probability estimates were derived from the medical literature and expert opinion. Costs estimates were obtained from the Medicare Fee schedule and the cost-analysis was done from a third party payer perspective. The target population was patients with uninvestigated symptoms suggestive of IBD. The outcome measure was cost per correct diagnosis in competing strategies and was assessed at 1 yr.

RESULTS

In the base case analysis, the serodiagnostic strategies were dominant; they were less costly and more accurate than the standard invasive strategies. Sequential serodiagnostic strategies resulted in the largest cost savings ($550 per average patient) with an average cost per correct diagnosis of $1640 compared to $2188 for standard invasive testing. Cost savings were attributable to a 39% reduction in the use of invasive tests. The results were robust to varying model estimates over prespecified ranges in the sensitivity analyses. When costs of invasive testing are reduced by 80% or the prevalence of IBD is at least 83%, serodiagnostic strategies are no longer the most cost-effective.

CONCLUSIONS

Initial serodiagnostic screening strategies may represent a cost-effective alternative to standard invasive diagnostic strategies. The economic benefits seem to be achieved by avoiding invasive evaluations in patients without IBD. Confirmation of these findings in a prospective comparative trial seems to be warranted.

Mutations in NOD2 are associated with fibrostenosing disease in patients with Crohn's disease

BACKGROUND & AIMS

The clinical manifestations of Crohn's disease (CD) are diverse, ranging from fibrostenosing small-bowel disease to colon-predominant inflammation. These distinctions may represent genetic, immunologic, and microbial heterogeneity. NOD2 gene mutations in CD have been described recently and may alter innate immune responses. We hypothesized that NOD2 mutations may be associated with distinct phenotypic expressions of CD.

METHODS

Two cohorts of consecutively identified patients referred to an inflammatory bowel disease center (n = 142 collected between 1993 and 1996; n = 59 collected between 1999 and 2001) were genotyped for 3 single nucleotide variants of NOD2-R675W, G881R, and 3020insC-and phenotyped for disease behavior, disease location, and serum immune markers.

RESULTS

Univariate analysis showed that CD-associated NOD2 variants were significantly associated with fibrostenosing disease in each cohort (P = 0.049 and P = 0.002, respectively). When both cohorts were analyzed together, the association between NOD2 variants and fibrostenosing disease was more significant (P = 0.001). These relationships were observed in both Jews and non-Jews. Forty-six percent of patients with fibrostenosing disease carried at least 1 of these alleles, compared with only 23.5% of patients without fibrostenosing disease (odds ratio, 2.8; 95% confidence interval, 1.6-5.2). Multivariate and conditioning analyses showed a primary association between NOD2 allelic variants and fibrostenosing disease, but not with small-bowel disease.

CONCLUSIONS

In this description of a genotype/phenotype correlation in CD patients and NOD2 variants, data suggest that variation in this gene contributes to the occurrence of fibrostenotic CD of the small bowel.

Autoimmune hepatitis: diagnostic criteria, subclassifications, and clinical features

The diagnosis of AIH depends on the finding of several suggestive features together with careful exclusion of liver diseases of other etiologies. Wherever possible, the diagnosis should be confirmed histologically by an experienced hepatopathologist. Seronegativity for the conventional autoantibodies at presentation does not exclude a diagnosis of AIH. It is important to test for anti-LKM1 antibodies to avoid missing a diagnosis of type 2 AIH, with potentially serious consequences. Although the syndrome is associated with characteristic biochemical abnormalities, and biochemical parameters are commonly used for monitoring response to therapy, it should be borne in mind that neither these nor autoantibody titers are completely reliable indices of disease activity. Although the various systems that have been promulgated for classification of the disease may identify different groups of patients on pathogenetic or clinical criteria and are useful for research purposes, none is yet sufficiently exclusive in terms of defining prognosis or planning treatment strategies to be applicable to the individual patient seen in the clinic. Clinical management should therefore continue to be individually tailored.

Type 1 autoimmune hepatitis in Turkish patients: absence of association with HLA B8

BACKGROUND

There is very little information about autoimmune hepatitis (AIH) in populations other than of white European or Japanese descent.

GOALS

To investigate the presenting features, immunogenetic background, and response to standard immunosuppressive therapy in native Turkish patients with AIH.

METHODS

Retrospective analysis of all patients referred between 1994 and 2000 to our hepatology clinic in Ankara who fulfilled international criteria for definite or probable type 1 or type 2 AIH.

RESULTS

Seventeen patients (15 female; median age, 31 years; range, 13-56 years) were identified. All had type 1 AIH. Clinical and laboratory features were broadly similar to those reported for white or Japanese patients. Five had the HLA DR3 allotype and 10 had DR4; however, in contrast to white and Japanese patients, DR4 was not associated with an older age at onset. Importantly, no patient had the B8 allotype (vs. 10.9% in 110 healthy Turkish subjects). Thus, none had the classic A1-B8-DR3 autoimmune haplotype: a major distinction from white individuals.

CONCLUSIONS

There appears to be genetic differences in type 1 AIH between Turkish and other populations. Genotyping of Turkish patients to identify alleles that may confer susceptibility or resistance to AIH may progress understanding of the genetic basis of the disease.

Neutrophil-specific autoantibodies in chronic inflammatory bowel diseases

This review intends to highlight important differences between neutrophil-specific autoantibodies (NSA) typically found in chronic inflammatory bowel diseases (CIBD) and anti-neutrophil cytoplasm antibodies (ANCA) associated with primary systemic small vessel vasculitides (SSVV). Indirect immunofluorescence (IF) techniques alone cannot distinguish NSA from ANCA and special measures must be taken to separate these two autoantibody populations. Many autoantigens originating in all cell compartments may be targeted by NSA in CIBD, several of these being constituents of neutrophil nuclei. Apart from the use of NSA in the differential diagnosis between Crohn's disease (CD) and ulcerative colitis (UC), very limited clinical significance is ascribed to these antibodies in CIBD. Laboratory reports on NSA-positivity must be clearly distinguishable from reports on ANCA to help avoid clinical misinterpretation.

Diagnostic methodologies: serology, endoscopy, and radiology

The two major inflammatory bowel diseases, Crohn's disease (CD) and ulcerative colitis (UC), represent clinicopathologic entities that traditionally have been diagnosed on the basis of a combination of clinical, radiologic, endoscopic, and histologic features. Serum perinuclear antineutrophil cytoplasmic antibodies (pANCA) and anti-Saccharomyces cerevisiae antibodies (ASCA) have recently been added to our diagnostic armamentarium. Several studies have demonstrated that UC-associated pANCAs recognize nuclear antigens. Additional studies have demonstrated that the pANCA human monoclonal antibody (mAb) Fab 5-3 reacts with histone H1 and with bacterial and mycobacterial antigens. Several reports have suggested that, in CD, pANCA and ASCA are correlated with colonic and small bowel disease respectively. One study found that higher ASCA levels were correlated with more aggressive CD. Serology may prove to be useful in predicting the evolution of indeterminate colitis. Magnetic resonance imaging (MRI) and leukocyte scintigraphy hold promise in identifying inflammatory CD. MRI enteroclysis is useful in identifying both luminal small bowel disease and extraluminal complications. A recent study of surveillance colonoscopy in extensive Crohn's colitis showed a high risk of dysplasia and cancer.

Molecular cloning of a Bacteroides caccae TonB-linked outer membrane protein identified by an inflammatory bowel disease marker antibody

Commensal enteric bacteria are a required pathogenic factor in inflammatory bowel disease (IBD), but the identity of the pertinent bacterial species is unresolved. Using an IBD-associated pANCA monoclonal antibody, a 100-kDa protein was recently characterized from an IBD clinical isolate of Bacteroides caccae (p2Lc3). In this study, consensus oligonucleotides were designed from 100-kDa peptides and used to identify a single-copy gene from the p2Lc3 genome. Sequence analysis of the genomic clone revealed a 2,844-bp (948 amino acid) open reading frame encoding features typical of the TonB-linked outer membrane protein family. This gene, termed ompW, was detected by Southern analysis only in B. caccae and was absent in other species of Bacteroides and gram-negative coliforms. The closest homologues of OmpW included the outer membrane proteins SusC of Bacteroides thetaiotaomicron and RagA of Porphyromonas gingivalis. Recombinant OmpW protein was immunoreactive with the monoclonal antibody, and serum anti-OmpW immunoglobulin A levels were elevated in a Crohn's disease patient subset. These findings suggest that OmpW may be a target of the IBD-associated immune response and reveal its structural relationship to a bacterial virulence factor of P. gingivalis and periodontal disease.

Animal models for primary sclerosing cholangitis

Since the aetiopathogenesis of primary sclerosing cholangitis (PSC) in humans remains undefined, investigators have studied a variety of animal models to gain insights into immunopathogenetic mechanisms associated with obliterative fibrous cholangitis of intra- and extra-hepatic bile ducts. To date, no animal model has been developed that exhibits all of the attributes of PSC. Rodent models instigated by bacterial cell components or colitis are promising because they may help to explain the strong association between PSC and inflammatory bowel disease (IBD). Other models of direct injury to biliary epithelia, peribiliary vascular endothelia or portal venous endothelia indicate that inflammation, chemokines and cytokines can produce diffuse sclerosis of bile ducts. Models of toxic, infectious or intra-luminal injury of the biliary tract also exhibit focal biliary sclerosis mediated by inflammation and cytokines. The histopathology of several models suggests a sequence of events beginning with secretion of proinflammatory cytokines by activated hepatic macrophages followed by peribiliary infiltration with CD4 and CD8 T cells with a T helper 1 phenotype. These results strongly suggest co-ordinated, pathogenetic roles for both the innate and adaptive immune responses. However, the stimuli that initiate and perpetuate peribiliary fibrosis remain unknown. Interestingly, several models are also associated with the development of anti-neutrophil cytoplasmic antibodies that react in a perinuclear and cytoplasmic pattern similar to that observed in patients with ulcerative colitis and/or PSC. Finally, models of extra-hepatic biliary obstruction continue to provide important information about the pathogenesis of portal fibrosis and secondary biliary cirrhosis that occurs in PSC and other diseases with obstruction of bile flow. Future studies in either existing or new animal models should advance our understanding of the pathogenesis of PSC, the major prerequisite for the development of effective therapies.

Evaluation of serologic disease markers in a population-based cohort of patients with ulcerative colitis and Crohn's disease

BACKGROUND

The sensitivity of assays for antineutrophil cytoplasmic antibody (ANCA), anti-Saccharomyces cerevisiae antibody (ASCA), and antipancreatic antibody (PAB) in different laboratories is unknown. Likewise, the sensitivity and diagnostic usefulness of these assays in patients with inflammatory bowel disease (IBD) in the community is unknown.

METHODS

An incidence cohort of 290 patients with IBD were offered participation in the study. Blood was obtained from 162 patients (56%) (83 with ulcerative colitis, 79 with Crohn's disease) who agreed to participate. ANCA was determined in five laboratories. ASCA in two laboratories, and PAB in one laboratory.

RESULTS

In ulcerative colitis, the sensitivity of ANCA determined in five laboratories varied widely, ranging from 0-63%. In Crohn's disease, the sensitivity of ASCA determined in two laboratories did not vary significantly, ranging from 39-44%; and the sensitivity of PAB determined in one laboratory was 15%. The optimal diagnostic usefulness was obtained from one laboratory where the positive predictive values of a positive ANCA assay combined with a negative ASCA assay for ulcerative colitis, and a negative ANCA combined with a positive ASCA for Crohn's disease, were 75% and 86%, respectively.

CONCLUSIONS

In patients with IBD, the sensitivity of ANCA varied widely in different laboratories, whereas the prevalence of ASCA was similar. The positive predictive values of the ANCA assay combined with the ASCA assay for ulcerative colitis and Crohn's disease are high enough to be clinically useful.