Anti-Saccharomyces cerevisiae mannan antibodies in familial Crohn's disease

[Multifactorial etiology and pathogenic factors in inflammatory bowel disease]

All the currently available evidence suggests that the two types of inflammatory bowel disease (IBD), Crohn's disease (CD) and ulcerative colitis (UC), involve a conflict between the immune system of the intestinal mucosa and intraluminal antigens, mainly the intestinal microflora, which are normally tolerated by the immune system. This conflict is modulated by numerous environmental factors and a clear polygenetic predisposition. The present article reviews the behavior of all the etiologic circumstances (microbial, genetic and environmental) and subsequently analyzes the possible pathogenic factors in which the etiologies can be found, namely: dysfunction of the intestinal epithelium, innate immune system alterations, and distortion of the cellular and humoral arms of the acquired immune system. The role of tissue ischemia in CD and expression of "extraintestinal inflammatory metastases", both in CD and UC, are briefly discussed. Finally, the view that IBD may be a spectrum of pathological processes provoked by distinct etiopathogenic factors and the possible biological significance of the growing incidence of this disease in the western world, coinciding with the decline in infectious diseases in this geographical area, are discussed.

Candida albicans colonization and ASCA in familial Crohn's disease

OBJECTIVES

Anti-Saccharomyces cerevisiae antibodies (ASCAs) are present in 50-60% of patients with Crohn's disease (CD) and in 20-25% of their healthy relatives (HRs). The yeast, Candida albicans, has been shown to generate ASCAs, but the presence of C. albicans in the digestive tract of CD patients and their HRs has never been investigated. Therefore, we studied C. albicans carriage in familial CD and its correlation with ASCAs.

METHODS

Study groups consisted of 41 CD families composed of 129 patients and 113 HRs, and 14 control families composed of 76 individuals. Mouth swabs and stool specimens were collected for isolation, identification, and quantification of yeasts. Serum samples were collected for detection of ASCAs and anti-C. albicans mannan antibodies (ACMAs).

RESULTS

C. albicans was isolated significantly more frequently from stool samples from CD patients (44%) and their HRs (38%) than from controls (22%) (P<0.05). The prevalence of ACMAs was similar between CD patients, their HRs, and controls (22, 19, and 21%, respectively, P=0.845), whereas the prevalence of ASCAs was significantly increased in CD families (72 and 34% in CD and HRs, respectively, in contrast to 4% in controls, P<0.0001). AMCA levels correlated with C. albicans colonization in all populations. ASCA levels correlated with C. albicans colonization in HRs but not in CD patients.

CONCLUSIONS

CD patients and their first-degree HRs are more frequently and more heavily colonized by C. albicans than are controls. ASCAs correlate with C. albicans colonization in HRs but not in CD. In HRs, ASCAs could result from an altered immune response to C. albicans. In CD, a subsequent alteration in sensing C. albicans colonization could occur with disease onset.

Fecal calprotectin levels and serological responses to microbial antigens among children and adolescents with inflammatory bowel disease

BACKGROUND

Noninvasive, sensitive, and specific tools for early identification of chronic inflammatory bowel disease (IBD) are needed for clinical practice. The aim was to identify new noninvasive test combinations for characterization of IBD in children and adolescents by comparing serological responses to microbial antigens and fecal calprotectin, a new promising marker for intestinal inflammation.

METHODS

Our study included 73 children who underwent endoscopies because of suspicion of IBD. Their sera were tested for antibodies to the Pseudomonas fluorescens-associated sequence I2, a Bacteroides caccae TonB-linked outer membrane protein, OmpW, and anti-Saccharomyces cerevisiae (ASCA). Simultaneously, samples for fecal calprotectin measurements were obtained from 55 subjects.

RESULTS

IBD was diagnosed in 60 patients (Crohn's disease [CD] in 18 patients, ulcerative colitis [UC] in 36, and indeterminate colitis [IC] in 6). Thirteen children had a non-IBD disease. Fecal calprotectin levels were elevated (>or=100 microg/g) more frequently in IBD patients (89%, 39/44) compared to non-IBD cases (9%, 1/11, P < 0.001). ASCA antibodies in sera were detected in 67% (12/18) of patients with CD, in 14% (5/36) of the children with UC, and in 50% (3/6) of patients with IC. Seroreactivity for I2 was observed in 42% of the IBD patients, this frequency being higher than in non-IBD cases (7.7% seropositive; P = 0.025). Serum anti-I2 IgA levels (median absorbances) were higher in those with IBD compared to those without gut inflammation (P = 0.039). The combination of the measurements of fecal calprotectin and serological responses to microbial antigens (ASCA, I2, and OmpW) identified 100% of CD patients (sensitivity 100%, specificity 36%, positive predictive value [PPV] 66%, negative predictive value [NPV] 100%) and 89% of UC patients (sensitivity 89%, specificity 36%, PPV 77%, NPV 57%).

CONCLUSIONS

Increased levels of serological responses to microbial antigens (ASCA, I2, and OmpW) and fecal calprotectin are evident in both CD and UC patients. The combination of these markers provides valuable, noninvasive tools for the diagnosis of IBD.

New serological biomarkers of inflammatory bowel disease

Serological biomarkers in inflammatory bowel disease (IBD) are a rapidly expanding list of non-invasive tests for objective assessments of disease activity, early diagnosis, prognosis evaluation and surveillance. This review summarizes both old and new biomarkers in IBD, but focuses on the development and characterization of new serological biomarkers (identified since 2007). These include five new anti-glycan antibodies, anti-chitobioside IgA (ACCA), anti-laminaribioside IgG (ALCA), anti-manobioside IgG (AMCA), and antibodies against chemically synthesized (Σ) two major oligomannose epitopes, Man α-1,3 Man α-1,2 Man (ΣMan3) and Man α-1,3 Man α-1,2 Man α-1,2 Man (ΣMan4). These new biomarkers serve as valuable complementary tools to existing biomarkers not only in differentiating Crohn’s disease (CD), ulcerative colitis (UC), normal and other non-IBD gut diseases, but also in predicting disease involvement (ileum vs colon), IBD risk (as subclinical biomarkers), and disease course (risk of complication and surgery). Interestingly, the prevalence of the antiglycan antibodies, including anti-Saccharomyces cerevisiae antibodies (ASCA), ALCA and AMCA, was found to be associated with single nucleotide polymorphisms (SNPs) of IBD susceptible genes such as NOD2/CARD15, NOD1/CARD4, toll-like receptors (TLR) 2 and 4, and β-defensin-1. Furthermore, a gene dosage effect was observed: anti-glycan positivity became more frequent as the number of NOD2/CARD15 SNPS increased. Other new serum/plasma IBD biomarkers reviewed include ubiquitination factor E4A (UBE4A), CXCL16 (a chemokine), resistin, and apolipoprotein A-IV. This review also discusses the most recent studies in IBD biomarker discovery by the application of new technologies such as proteomics, fourier transform near-infrared spectroscopy, and multiplex enzyme-linked immunosorbent assay (ELISA)’s (with an emphasis on cytokine/chemokine profiling). Finally, the prospects of developing more clinically useful novel diagnostic algorithms by incorporating new technologies in serological biomarker profiling and integrating multiple biomarkers with bioinformatics analysis/modeling are also discussed.

Fungi and inflammatory bowel diseases: Alterations of composition and diversity

OBJECTIVE

Altered bacterial diversity of the intestinal mucosa-associated microbiota may reflect the net influence of lifestyle factors associated with the development of chronic inflammatory bowel diseases (IBD). While a reduced bacterial diversity has been reported in IBD, little is known about the fungal microbiota. The aim of this study was to carry out a systematic analysis of intestinal fungal microbiota in IBD.

MATERIAL AND METHODS

The mucosa-associated fungal microbiota of 104 colonic biopsy tissues from 47 controls and 57 IBD patients was investigated using metagenomic 18S rDNA-based denaturing gradient gel electrophoresis (DGGE), clone libraries, sequencing, and in situ hybridization techniques.

RESULTS

Fungi-specific 18S rDNA signatures could be detected in all 104 patients, accounting for only a small proportion of the intestinal microbiota (0.02% of the mucosal and 0.03% of the fecal microbiota). An overall fungal biodiversity of 43 different operational taxonomic units (OTUs) was found in the clone libraries. The qualitative composition of fungal microbiota was different between patients with IBD and controls. The DGGE profiles showed a higher mean fungal diversity in patients with Crohn's disease (CD) in comparison with controls (10.8+/-3.1 versus 6.2+/-2.4 for CD, p <or= 0.001). No disease-specific fungal species were found in the CD and ulcerative colitis (UC) group.

CONCLUSIONS

Diverse fungal species are part of the normal enteric microbiota, but diversity is increased and composition of the fungal communities varies in IBD. Further work is needed to investigate whether the alteration of the fungal flora in IBD is secondary to an imbalanced bacterial microbiota or an independent etiologic factor.

Current understanding of fungal microflora in inflammatory bowel disease pathogenesis

Inflammatory bowel diseases are a current and growing public health problem, with a prevalence that appears to be increasing in most countries and cultures. While most research into the triggering phenomenon has focused on the interaction between commensal bacteria and inflammatory bowel disease, enteric fungi may also be important in determining disease susceptibility. Herein we review what is known about enteric fungi and the mechanisms by which they and their dysregulation might be involved in triggering inflammatory diseases of the bowel.

Anti-Saccharomyces cerevisiae antibodies in primary biliary cirrhosis

AIM

The aim of this study was to evaluate, retrospectively, the frequency of anti-Saccharomyces cerevisiae antibodies (ASCA) in patients with primary biliary cirrhosis (PBC).

METHODS

ASCA, IgG, and IgA, were determined by ELISA in sera of 95 PBC patients; 80 healthy blood donors served as controls.

RESULTS

The frequency of ASCA (IgG or IgA) was significantly higher in PBC patients than in the control group (24.2% vs 3.7%, P = 0.0001). The frequency of ASCA IgG and ASCA IgA in PBC patients was also significantly higher than that found in the control group (18.9% vs 2.5%, P = 0.0006 and 11.6% vs 1.2%, P = 0.007, respectively). Six patients out of 95 (6.3%) had both ASCA IgG and ASCA IgA; in contrast, none of the control group had both isotypes (P = 0.02). There was no correlation between ASCA levels and mitochondrial autoantibodies (AMA) titres in PBC patients.

CONCLUSION

We conclude that ASCA are common in patients with PBC.

(Auto)antibodies in inflammatory bowel diseases

Patients who have inflammatory bowel diseases (IBD) express strong antibody responses to a variety of epitopes. A number of (auto)antibodies have been described in patients who have Crohn's disease or ulcerative colitis. These markers reflect a loss of tolerance toward bacterial and fungal flora and have been studied for their clinical value in IBD patients. However, currently, they have no place in the diagnostic work up. Their real promise may lie in their use as surrogate markers of complicated aggressive disease as shown in various retrospective studies, but prospective data are lacking.

Elevated serum anti-Saccharomyces cerevisiae, anti-I2 and anti-OmpW antibody levels in patients with suspicion of celiac disease

OBJECTIVES

Expression of anti-Saccharomyces cerevisiae antibodies (ASCA) identifies patients and individuals at risk for Crohn's disease and has also been reported in 40-60% of celiac disease (CD) cases, suggesting a role of host response to enteric microbiota in the development of inflammatory lesions. In this prospective study in patients with suspicion of CD, we evaluate the frequency and association of ASCA to serological responses for other host microbial targets formally associated with Crohn's disease, including the Pseudomonas fluorescens associated sequence I2 and a Bacteroides caccae TonB-linked outer membrane protein, OmpW.

METHODS

Small bowel mucosal biopsies were taken from 242 patients with suspicion of CD, their sera were tested for antibodies to tissue transglutaminase (tTG), ASCA, I2, and OmpW. Eighty adult healthy blood donors were used as controls.

RESULTS

The diagnosis of CD was confirmed on biopsy in 134 cases. The occurrence of ASCA and I2 positivity was significantly higher in adult CD patients than in patients with non-CD disease. Anti-I2 levels in the sera were significantly higher in adult CD patients than in non-CD disease or the controls and anti-OmpW levels in CD and non-CD patients when compared to controls. Positive seroreactivity to OmpW seemed to increase with age. Of the CD patients, 90% were seropositive for at least one microbial antigen tested.

CONCLUSIONS

This study demonstrates a mosaic of disease-related serological responses to microbial antigens in patients with CD. Immune responses to commensal enteric bacteria may play a role in the small intestine mucosal damage in CD.

IgG antibodies against common gut bacteria are more diagnostic for Crohn's disease than IgG against mannan or flagellin

INTRODUCTION

Antibodies to baker's yeast (mannan) have been widely used to aid in diagnosis of Crohn's disease. Recently, there has been interest in antibodies against a flagellin from Clostridium coccoides subphylum. We hypothesized that reactivity with these antigens is a surrogate marker for a generalized increased IgG response against intestinal microbiota in Crohn's disease.

METHODS

We compared the diagnostic utility of IgG antibodies against flagellin and mannan with two complex surface antigen preparations, one derived from B. vulgatus (Bv), the other from over 20 common mucosa-associated microbiota, a multibacterial membrane preparation (MBP). IgG antibodies were measured in sera from two age- and sex-matched populations: 120 Crohn's patients (CD) and 160 gastroenterology controls (CON) comprising 40 ulcerative colitis (UC) and 120 non-IBD patients.

RESULTS

IgG was elevated against all antigen preparations in Crohn's but statistical analysis of receiver operator characteristic (ROC) plots showed that IgG against the complex antigen preparations MBP and Bv had better diagnostic accuracy to distinguish the two populations (CD and CON) than IgG against mannan (P < or = 0.01) or flagellin (P < or = 0.04). Concentrations of antibody reactive with distinct individual antigens correlated weakly.

DISCUSSION

The findings support our hypothesis that measurement of IgG reactivity against individual antigens gives an indication of a generalized increased IgG response against individual intestinal microbiota in Crohn's, rather than measuring specific immune responses important for pathogenesis. The data are consistent with either a mucosal defect that facilitates increased exposure to microbial antigens or an altered immune response, both of which could occur due to known genetic and molecular defects in Crohn's disease.

Serologic markers in inflammatory bowel disease: tools for better diagnosis and disease stratification

In the last decade, new serologic markers have been identified, and attempts to delineate their potential roles in inflammatory bowel disease diagnosis, determination of prognosis and identification of apparently healthy subjects at risk have significantly increased our knowledge. In this review, the major serologic markers will be described, focusing on their common features as a group. It is predicted that within the next 5 years, panels of antibodies will prove to have a significant impact on disease diagnosis and stratification, as well as on the identification of populations at risk and the prediction of response to treatment. Thus, it is expected that they will become useful clinical tools that will enable an improved, 'tailored' approach to inflammatory bowel disease patients.

IBD serological panels: facts and perspectives

Beyond a defective innate immune response in inflammatory bowel disease (IBD), an increased immunological response toward microbial and self antigens has been intrinsically linked to the pathogenesis of such common immunopathologies of the gut. Mounting evidence indicates that increased seroreactivity toward certain antigens are a predictive and quantitative heritable trait, including the anti-Saccharomyces cerevisiae antibody (ASCA). Consistently, Candida albicans and Crohn's disease-associated NOD2 mutations have been recently identified as immunogen and genetic determinants for ASCA, respectively. In clinical practice, current panels of serological markers are not recommended for diagnosis, stratifying, and monitoring IBD. Therefore, prospective studies and highly sensitive serological panels of markers are eagerly awaited before guiding clinical decisions. Better understanding of the serological response in IBD might also provide new insights into their epidemiology and pathophysiology.

Evaluation of different mannan polysaccharide usage in enzyme-linked immunosorbent assay for specific antibodies determination

Polysaccharides as antigens impose the problem of the proper ELISA assay. The indirect coating using biotin-avidin or lectins are therefore used. We tried to clarify the efficiency of different approaches to this problem. Our experiments clearly demonstrate that direct coating with mannan polysaccharide on high binding ELISA plates is superior to any other combination using any intermediate protein. On the other hand, the direct coating of the normal ELISA plate with mannan was of significantly lower (P=0.008) efficiency. The use of protein cannot be avoided in normal microplates. All previous statements are supported by experimental data in the paper.

[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.

Ethnic and socio-cultural specificities in Tunisia have no impact on the prevalence of anti-Saccharomyces cerevisiae antibodies in Crohn's disease patients, their relatives or associated clinical factors

BACKGROUND

In Western Europe and the USA, the presence of anti-Saccharomyces cerevisiae antibodies (ASCAs) in Crohn's disease (CD) patients and their healthy relatives suggests that ASCAs may be influenced by genetic and/or environmental factors.

OBJECTIVES

To assess the prevalence of ASCAs in Tunisian patients with CD or ulcerative colitis (UC), and unaffected family members, in relation to clinical phenotype. Patients and methods. Seventy-seven patients (39 CD, 38 UC), 66 healthy relatives of CD patients, 16 relatives of UC patients and 70 healthy controls were studied. ASCAs were quantified with a new isotype-specific ELISA test involving an antigenic extract from S. cerevisiae strain W303 and by the original test which detects total immunoglobulins against S. cerevisiae Su1 mannan.

RESULTS

The specificity of the two tests was identical (91%). The isotype-specific ASCA W303 test was more sensitive than the ASCA Su1 test for immunoglobulin detection, but some CD patients were positive only with this latter test. A high percentage of patients with CD (72%) and their unaffected family members (35%) were ASCA-positive in contrast to UC patients (16%) and their relatives (0%) and controls (8.6%). ASCAs were shown to be independent of rural or urban living, disease activity, but were associated with ileal location. The antigen of S. cerevisiae strain W303 discriminated patients depending on age at onset or location of the disease.

CONCLUSION

This study confirms the antigenic heterogeneity of S. cerevisiae strains in their ability to detect ASCA. It suggests that ASCAs are markers of immunoregulatory disturbance in CD, independently of ethnic/cultural differences between Europe, the USA and North Africa.

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.

NOD2 variants and antibody response to microbial antigens in Crohn's disease patients and their unaffected relatives

BACKGROUND & AIMS

The Cdcs1 locus of the C3Bir mouse confers severe colitis associated with a decrease in innate immune function and an increase in adaptive T-cell responses to commensal bacterial products. The aim of our study was to determine if defects in innate immunity are similarly associated with increased adaptive immune responses to microbial antigens in Crohn's disease patients.

METHODS

Sera from 732 patients, 220 unaffected relatives, and 200 healthy controls were tested for antibodies to oligomannan, the Pseudomonas fluorescens-related protein, Escherichia coli outer membrane porin C, CBir1 flagellin, and DNA from the same subjects was tested for 3 Crohn's disease-associated variants of the NOD2 gene, and 5 toll-like receptor (TLR) 2, 2 TLR4, and 2 TLR9 variants. The magnitude of responses to microbial antigens was examined according to variant status.

RESULTS

NOD2 variant carriage increased in frequency with increasing number of positive antibodies and increasing cumulative quantitative response as measured by quartile sum (P for trend, .0008 and .0003, respectively). Mean antibody and quartile sums were higher for patients carrying any NOD2 variant versus those carrying none (2.24 vs 1.92 and 10.60 vs 9.72; P = .0008 and P = 0.0003, respectively). The mean quartile sum was higher for unaffected relatives carrying any NOD2 variant versus those carrying none (10.67 vs 9.75, respectively; P = .02). No association was found between any TLR variant and the magnitude of response.

CONCLUSIONS

Patients with Crohn's disease and unaffected relatives carrying variants of the NOD2 gene have increased adaptive immune responses to microbial antigens.

Fecal calprotectin in first-degree relatives of patients with ulcerative colitis

OBJECTIVES

The pathogenesis of inflammatory bowel disease seems to depend on the combination of genetic and environmental factors. To evaluate genetic susceptibility, one approach is to search for specific markers in apparently unaffected family members of patients. Our aim was to evaluate fecal calprotectin concentrations (FCCs) in first-degree relatives of patients with ulcerative colitis (UC).

PATIENTS

Fifty-five patients with UC and 167 healthy first-degree relatives were recruited; 38 of the patients' spouses were also enrolled. One hundred fifty healthy subjects participated as the control group.

METHODS

FCCs were determined by ELISA. FCCs were compared among the groups by Kruskal-Wallis analysis of variance (ANOVA) test followed by Mann-Whitney U test.

RESULTS

Significantly greater FCCs were found in first-degree relatives of patients with UC (76.0 [34.7-129.6] microg/g) as compared with controls (31.6 [17.0-45.0]) (P < 0.0001). Fecal calprotectin levels in patients with UC (256.0 [153.0-356.0] microg/g) were significantly higher as compared with first-degree relatives, spouses (43.8 [18.6-89.0] microg/g), and controls (P < 0.0001 for all comparisons). FCC of relatives was significantly higher than FCC of spouses (P = 0.01). FCC of spouses had a significantly higher FCC with respect to controls (P = 0.01).

CONCLUSIONS

First-degree relatives of patients with UC had greater FCC values and could have a subclinical intestinal inflammation. It needs to be clarified if this finding is the consequence of genetic predisposition, of environmental factors, or the interaction of both, and if relatives with high FCC have a greater risk of developing the disease.

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.

Multilocus sequence typing reveals intrafamilial transmission and microevolutions of Candida albicans isolates from the human digestive tract

Candida albicans is a human commensal that is also responsible for superficial and systemic infections. Little is known about the carriage of C. albicans in the digestive tract and the genome dynamics that occur during commensalisms of this diploid species. The aim of this study was to evaluate the prevalence, diversity, and genetic relationships among C. albicans isolates recovered during natural colonization of the digestive tract of humans, with emphasis on Crohn's disease patients who produce anti-yeast antibodies and may have altered Candida sp. carriage. Candida sp. isolates were recovered from 234 subjects within 25 families with multiple cases of Crohn's disease and 10 control families, sampled at the oral and fecal sites. Prevalences of Candida sp. and C. albicans carriage were 53.4% and 46.5%, respectively, indicating frequent commensal carriage. No differences in prevalence of carriage could be observed between Crohn's disease patients and healthy subjects. Multilocus sequence typing (MLST) of C. albicans isolates revealed frequent colonization of a subject or several members of the same family by genetically indistinguishable or genetically close isolates. These latter isolates differed by loss-of-heterozygosity events at one or several of the MLST loci. These loss-of-heterozygosity events could be due to either chromosome loss followed by duplication or large mitotic recombination events between complementary chromosomes. This study was the first to jointly assess commensal carriage of C. albicans, intrafamilial transmission, and microevolution. The high frequency of each of these events suggests that the digestive tract provides an important and natural niche for microevolutions of diploid C. albicans through the loss of heterozygosity.

Anti-Saccharomyces cerevisiae antibody titers are stable over time in Crohn's patients and are not inducible in murine models of colitis

AIM

To investigate ASCA production over time in CD and murine colitis in order to further our understanding of their etiology.

MATERIALS AND METHODS

Sixty-six CD patients were compared to ulcerative colitis (UC) and irritable bowel syndrome patients with respect to ASCA production as measured by ELISA. ASCA IgG or IgA positivity as well as change in titers over a period of up to 3 years (Delta IgG/A) was correlated with clinical parameters such as CD activity index (CDAI) and C-reactive protein levels (CRP). Moreover, two murine models of colitis (DSS and IL-10 knock out) were compared to control animals with respect to ASCA titers after oral yeast exposure.

RESULTS

ASCA IgG and IgA titers are stable over time in CD and non-CD patients. Fistular disease was associated with a higher rate of ASCA IgA positivity (P = 0.014). Ileal disease was found to have a significant influence on the Delta IgG of ASCA (P = 0.032). There was no correlation found between ASCA positivity or Delta IgG/A and clinical parameters of CD: CDAI and CRP. In mice, neither healthy animals nor animals with DSS-induced or spontaneous colitis exhibited a marked increase in ASCA titers after high-dose yeast exposure. On the other hand, mice immunized intraperitoneally with mannan plus adjuvant showed a marked and significant increase in ASCA titers compared to adjuvant-only immunized controls (P = 0.014).

CONCLUSION

The propensity to produce ASCA in a subgroup of CD patients is largely genetically predetermined as evidenced by their stability and lack of correlation with clinical disease activity parameters. Furthermore, in animal models of colitis, mere oral exposure of mice to yeast does not lead to the induction of marked ASCA titers irrespective of concomitant colonic inflammation. Hence, environment may play only a minor role in inducing ASCA.

Candida albicans is an immunogen for anti-Saccharomyces cerevisiae antibody markers of Crohn's disease

BACKGROUND AND AIMS

Antibodies directed against oligomannose sequences alpha-1,3 Man (alpha-1,2 Man alpha-1,2 Man)(n) (n = 1 or 2), termed anti-Saccharomyces cerevisiae antibodies (ASCAs) are markers of Crohn's disease (CD). S. cerevisiae mannan, which expresses these haptens, is used to detect ASCA, but the exact immunogen for ASCA is unknown. Structural and genetic studies have shown that Candida albicans produces mannosyltransferase enzymes that can synthesize S cerevisiae oligomannose sequences depending on growth conditions. This study investigated whether C. albicans could act as an immunogen for ASCA.

METHODS

Sequential sera were collected from patients with CD, systemic candidiasis, and rabbits infected with C. albicans. Antibodies were purified by using chemically synthesized (Sigma) ASCA major epitopes. These affinity-purified antibodies and lectins were then used to analyze the expression of ASCA epitopes on molecular extracts and cell walls of C. albicans and S cerevisiae grown in various conditions.

RESULTS

In humans and rabbits, generation of ASCA was shown to be associated with the generation of anti-C. albicans antibodies resulting specifically from infection. By using affinity-purified antibodies, C. albicans was shown to express ASCA epitopes on mannoproteins similar to those of S. cerevisiae. By changing the growth conditions, C. albicans mannan was also able to mimic S. cerevisiae mannan in its ability to detect ASCA associated with CD. This overexpression of ASCA epitopes was achieved when C. albicans grew in human tissues.

CONCLUSIONS

C. albicans is one of several immunogens for ASCA and may be at the origin of an aberrant immune response in CD.

Familial expression of anti-Escherichia coli outer membrane porin C in relatives of patients with Crohn's disease

BACKGROUND & AIMS

Crohn's disease (CD) is a genetically complex disorder with strong familial aggregation. Pathogenesis appears to involve dysregulation of the immune response to endogenous bacteria. Anti-Escherichia coli outer membrane porin C (anti-OmpC) expression reflects an exaggerated response to commensal bacteria and occurs with higher frequency in CD. The aim of this study was to determine whether there is familial aggregation and genetic determination of anti-OmpC expression in CD families.

METHODS

Study groups consisted of 787 CD patients, 389 ulcerative colitis (UC) patients, 619 unaffected relatives, and 216 healthy controls. Serum anti-OmpC was detected by enzyme-linked immunosorbent assay.

RESULTS

CD patients had a greater percentage of anti-OmpC than UC patients and healthy controls. Anti-OmpC expression was more frequent in unaffected relatives from CD-only or mixed families, compared with healthy controls (P = .002 and .0001, respectively), and it was more frequent in UC patients from mixed families than those from UC-only families (P = .02). There was a significant familiality in anti-OmpC expression: P = .02 for qualitative concordance and P < .0001 for quantitative intraclass correlation. The heritability estimate for anti-OmpC level was .39 (P < .0001).

CONCLUSIONS

Anti-OmpC is a heritable immunophenotype. Increased anti-OmpC expression in the unaffected family members of CD patients suggests that anti-OmpC may be an immunologic risk marker for CD. That UC patients in mixed families had a higher response to OmpC than those in UC-only families indicates pathophysiologic heterogeneity within UC.

Correlation between Saccharomyces cerevisiae DNA in intestinal mucosal samples and anti-Saccharomyces cerevisiae antibodies in serum of patients with IBD

AIM: To investigate the correlation between ASCA and presence of mucosal S. cerevisiae DNA in a population of CD, ulcerative colitis (UC) patients and controls.

METHODS: S. cerevisiae-specific primers and a fluorescent probe were designed for a 5’ exonuclease real time PCR (TaqMan^TM) assay, which is a homogenous system using a fluorescent-labelled probe for the detection of PCR product in real time. We analyzed the relation of the PCR results with the ASCA findings in a group of 76 inflammatory bowel disease (IBD) patients (31 CD, 45 UC) and 22 healthy controls (HC).

RESULTS: ASCA (IgA or IgG) were positive in 19 (61%) patients with CD, 12 (27%) with UC and none of the HC. PCR amplification was inhibited and excluded from the final results in 10 (22%) UC patients, 7 (22%) CD patients, and 6 (30%) HC. In only 15 of the mucosal samples, S. cerevisiae DNA was detected by real time PCR, including 7 (29%) in CD, 7 (19%) in UC, 1 (6%) in HC. In 4 CD and in 4 UC patients, ASCA and mucosal S. cerevisiae were positive. Mucosal S. cerevisiae was present in combination with negative ASCA IgA and IgG in 3 UC, and 3 CD patients.

CONCLUSION: We conclude that since the presence of S. cerevisiae in colonic mucosal biopsy specimens is very rare, ASCA is unlikely to be explained by continuous exposure to S. cerevisiae in the mucosa. Therefore, ASCA formation must occur earlier in life and levels remain relatively stable thereafter in immunological susceptible persons.

Current status of genetics research in inflammatory bowel disease

The research on genetic susceptibility of inflammatory bowel diseases (IBD) has been tremendous and over 10 chromosomal regions have been identified by genome-wide scanning. Further fine mapping as well as candidate gene studies have already led to the identification of a number of susceptibility genes including CARD15, DLG5, OCTN1 and 2, NOD1, HLA, and TLR4. The CARD15 gene is undoubtedly replicated most widely and most understood at present. CARD15 is involved in the recognition of bacterial peptidoglycan-derived muramyl dipeptide (MDP) and will stimulate secretion of antimicrobial peptides including alpha-defensins (also called cryptdins) to protect the host from invasion. Genetic research in IBD has advanced our understanding of the clinical heterogeneity of the disease and has started to tackle the complex interactions between genetic risk factors and environmental risk factors in IBD. Genes also interfere with the metabolization of drugs and may influence the clinical response and the drug-related toxicity. Interesting pharmacogenetic data with respect to steroids, azathioprine, and infliximab have been generated in IBD. Overall, it is anticipated that genetic markers in the future will be implemented in an integrated molecular diagnostic and prognostic approach of our patients.

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.

Inflammatory bowel disease: dysfunction of GALT and gut bacterial flora (I)

Gut-associated lymphoid tissue (GALT) is the largest lymphoid organ in the body. This is not surprising considering the huge load of antigens (Ags) from food and commensal bacteria with which it interacts on a daily basis. Gut-associated lymphoid tissue has to recognise and allow the transfer of beneficial Ags whilst concurrently dealing with and successfully removing putative and overtly harmful Ags. This distinctive biological feature of GALT is believed to be crucial to good health. Deregulation or dysfunction of GALT is thought to predispose to inflammatory bowel diseases (IBD) such as ulcerative colitis and Crohn's disease. The exact mechanism(s) underlying the pathogenesis of IBD is (are) poorly understood and the immunological defects in GALT are poorly documented. Advances in immunology have highlighted the importance of dendritic cells (DCs), which are the key Ag presenting cells in tissues and lymphoid compartments. Their crucial role in GALT, in health and disease is discussed in this review. Interaction of DCs with T cells in the gut produces a subset of T lymphocytes, which have immunosuppressive function. Inappropriate Ag uptake and presentation to naïve T cells in mesenteric lymph nodes may lead to T cell tolerance in GALT. These various complex factors in the gut are discussed and their possible relevance to IBD evaluated.

Anti-Saccharomyces cerevisiae mannan antibodies in inflammatory bowel disease: comparison of different assays and correlation with clinical features

BACKGROUND

Anti-Saccharomyces cerevisiae mannan antibodies have been proposed as a new serological marker associated with Crohn's disease. However, their clinical value is still unclear; furthermore, a standardization of anti-S. cerevisiae mannan measurements is lacking.

AIM

In this study, we aimed to assess the correlation between anti-S. cerevisiae mannan detection and specific clinical features in Crohn's disease and ulcerative colitis. Moreover, we tested the concordance of four different anti-S. cerevisiae mannan assays.

MATERIALS AND METHODS

Serum samples from 196 patients with Crohn's disease, 197 patients with ulcerative colitis and 100 unrelated healthy controls were tested for anti-S. cerevisiae mannan with a standard enzyme-linked immunosorbent assay method (Lille) by one of the authors (VP). Subsequently, 60 randomly selected serum samples (27 Crohn's disease, 28 ulcerative colitis and five healthy controls) were tested for anti-S. cerevisiae mannan with three different commercial kits.

RESULTS

With the Lille assay, anti-S. cerevisiae mannan were detected in 100 of 196 patients with Crohn's disease (51%; P < 0.0001 vs. controls), 32 of 197 patients with ulcerative colitis (16%; P < 0.02 vs. controls), and six of 100 controls (6%). No correlation between presence of anti-S. cerevisiae mannan and specific clinical features was found in both ulcerative colitis and Crohn's disease patients. The percentages of anti-S. cerevisiae mannan detected with four different assays ranged from 28 (Bouty) up to 43% (Inova), but these differences did not reach statistical significance. The concordance rate of anti-S. cerevisiae mannan detection in the four assays was very low (11 concordant results of 60 samples, 18.3%) (k = 0.15). No improvement of the concordance rate was obtained by modifying the suggested cut-off values (k = 0.20).

CONCLUSION

In this study, we confirm that anti-S. cerevisiae mannan are significantly more frequent in Crohn's disease patients compared with ulcerative colitis patients (P < 0.0001) and controls. However, no correlation with clinical features was found in both ulcerative colitis and Crohn's disease. The low prevalence of anti-S. cerevisiae mannan, at least in our population, and the low concordance rate between different assays, makes the clinical role of this marker questionable.

IBD: a family affair

The recent molecular advances in the understanding of the genetics of inflammatory bowel disease (IBD) have their grounding in studies examining IBD within different family groups and populations. The risk of IBD is highest in first-degree relatives of an IBD proband but more distant relatives are also at increased risk. The risk is higher for relatives of a CD proband. The risks of developing IBD for 'high-risk' relatives might be as great as 1 in 3 but in general first-degree relatives have a 1 in 10-20 risk. Three recent systematic studies have identified a total of 326 European twin pairs to examine disease concordance rates. The derived heritability in Crohn's disease is greater than for many complex diseases and is currently under detailed examination. Strong concordance has been shown, in particular for disease type and disease location, in multiplex families and twin studies. More than 75% children are diagnosed with IBD at a younger age than their parents but true genetic anticipation appears unlikely.

Recent advances in the diagnosis and classification of inflammatory bowel disease

The availability of an increasing number of inflammatory bowel disease (IBD)-specific serologic antibodies, the discovery of disease-susceptibility genes, the introduction of pharmacogenetic markers, and the recent application of wireless capsule enteroscopy to the evaluation of patients with IBD are providing new types of information that must be integrated with more traditional IBD paradigms. The challenge facing researchers and clinicians is to determine how to incorporate these potentially clinically relevant insights into our understanding of disease pathogenesis and to define the spectrum of potential applications to the management of patients with IBD. The ultimate diagnostic and predictive value of these tests will likely be optimized when they are applied in combination, rather than individually. As the clinical relevance of this expanding diagnostic armamentarium is defined, it is hoped that these tests will enable clinicians not only to diagnose IBD accurately but also to determine disease patterns prospectively, suggest prognoses, and allow for individualization of therapeutic regimens.

Diagnostic role and clinical correlates of anti-Saccharomyces cerevisiae antibodies (ASCA) and anti-neutrophil cytoplasmic antibodies (p-ANCA) in Italian patients with inflammatory bowel diseases

BACKGROUND

Anti-Saccharomyces cerevisiae antibodies (ASCA) and perinuclear anti-neutrophil cytoplasmic antibodies (p-ANCA) are serological markers associated, respectively, with Crohn's disease and ulcerative colitis, whose clinical significance and possible diagnostic role are still poorly defined.

AIMS

(a) To evaluate the sensitivity, specificity and predictive values of isolated and combined ASCA and p-ANCA assays in a large cohort of Italian patients with inflammatory bowel disease (IBD) and (b) to assess whether their presence is associated with particular clinical features of the disease.

PATIENTS AND METHODS

Hundred and forty-six IBD patients (93 with Crohn's disease and 53 with ulcerative colitis) and 54 control patients were enrolled in the study. ASCA (IgA and IgG) and p-ANCA were determined by means of enzyme-linked immunosorbent assay and indirect immunofluorescence, respectively.

RESULTS

The specificities were excellent for both tests (ASCA in Crohn's disease, 98.1% both for IgA and IgG, and p-ANCA in ulcerative colitis, 92.5%); however, the sensitivities of both tests were low (59.1% for ASCA IgA, 44.1% for ASCA IgG, 39.6% for p-ANCA). ASCA specificity and positive predictive value reached 100% when positivity for both IgA and IgG was present. No significant association was found between the presence of a specific serological marker and patients' clinical features.

CONCLUSIONS

This study confirms the low prevalence of p-ANCA observed in ulcerative colitis patients from the Mediterranean area. The low sensitivity of ASCA and p-ANCA, despite their rather high specificity, renders them of little value in the screening of the general population, where the prevalence of IBD is low. However, in our series, a double positivity for ASCA IgA and IgG identifies with certainty the presence 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.

What are the major arguments in favour of the genetic susceptibility for inflammatory bowel disease?

Epidemiological data, notably concordance rates in twin pairs and familial aggregation, have provided strong evidence for the importance of the genetic contribution in inflammatory bowel diseases. Genome wide scanning has been remarkably successful in identifying a number of susceptibility loci. The identification of the IBD1 gene on chromosome 16 as NOD2/CARD15 definitely establishes that a significant proportion of Crohn's disease has an underlying genetic cause. In addition, our knowledge of the clinical impact of other genes in modelling disease phenotypes has increased in parallel. These results have led to great optimism that important clinical applications will result from genetic research in the near future.

Anti-Saccharomyces cerevisiae antibodies (ASCA) and autoimmune liver diseases

Antibodies to the baker's yeast Saccharomyces cerevisiae (ASCA), recently proposed as a serological marker of Crohn's disease, have also been detected in other autoimmune disorders. The aim of this study was to determine prevalence and clinical significance of ASCA in autoimmune liver disease. The presence of IgG and IgA ASCA was evaluated using a commercially available immunoassay in 215 patients with autoimmune liver disease (primary biliary cirrhosis, PBC, 123 cases; autoimmune hepatitis, AIH, 67 cases; primary sclerosing cholangitis, PSC, 25 cases), 48 with inflammatory bowel disease and 19 healthy blood donors. Anti neutrophil cytoplasmic antibodies with the perinuclear pattern (p-ANCA) were assessed by indirect immunofluorescence in PSC patients. The main clinical and biochemical parameters between ASCA-positive and negative patients were analysed and compared. ASCA are predominant in Crohn's disease (70%); among liver patients, PSC and AMA-negative PBC show the highest ASCA prevalence (53% and 44%). In PBC ASCA correlate with higher levels of circulating IgA (P < 0.05). In PSC the detection of either ASCA or p-ANCA is neither associated with any clinical or biochemical feature, nor with an underlying inflammatory bowel disease. ASCA can not be considered an additional serological marker of autoimmune liver disease, but the possibility of detecting such a reactivity in autoimmune liver disorders should be considered; their correlation with elevated IgA in PBC suggests that ASCA may be an indirect sign of enhanced mucosal immunity; in PSC patients neither ASCA nor p-ANCA predict the occurrence of a concomitant inflammatory bowel disease.

Anti-saccharomyces cerevisiae IgA antibodies are raised in ankylosing spondylitis and undifferentiated spondyloarthropathy

OBJECTIVES

To investigate whether anti-Saccharomyces cerevisiae antibodies (ASCA), a marker for Crohn's disease (CD), are present in spondyloarthropathies (SpA) and in the subgroups ankylosing spondylitis (AS), undifferentiated SpA (uSpA), and psoriatic arthritis (PsA), in comparison with healthy and inflammatory controls (patients with rheumatoid arthritis (RA)).

METHODS

ASCA IgA and IgG levels were measured with an enzyme linked immunosorbent assay (ELISA) kit (Medipan, Germany) in 26 patients with CD, 108 patients with SpA (43 patients with AS, 20 patients with uSpA, 45 patients with PsA), 56 patients with RA and 45 healthy controls. Gut biopsy samples were available in 18 AS and 10 patients with uSpA, these samples were screened for the presence of inflammation.

RESULTS

Both ASCA IgG and IgA levels were raised in CD compared with healthy controls and patients with RA. ASCA IgA, but not IgG levels, were higher in SpA than in both healthy and RA controls. ASCA IgA levels were raised in AS and uSpA, but not in PsA. No significant differences in ASCA IgA levels were noted between patients with SpA with and without histological gut inflammation.

CONCLUSION

ASCA IgA levels are significantly higher in SpA, and more specifically in AS, than in healthy controls and patients with RA. This is the first serum marker associated with SpA. No correlation between the presence of subclinical bowel inflammation and ASCA IgA levels was noted. However, it remains to be evaluated whether patients with SpA with ASCA have an increased risk of developing CD.

Cross-reactivity of yeast antigens in human colon and peripheral leukocytes

Elevation of the serum anti-Saccharomyces cerevisiae antibody (ASCA) level has been reported in patients with Crohn's disease. This study investigated the antigenic distribution of S. cerevisiae in human colon and peripheral leukocytes. ASCA was isolated from sera from patients with Crohn's disease using immuno-affinity chromatography and then biotinylated and assayed immunohistologically and immunocytologically to determine the distribution of antigens recognized by ASCA in human colon and peripheral leukocytes. Immunoblot analysis of yeast extract and human peripheral leukocytes was performed. Immunohistological study using biotinylated ASCA revealed the presence of yeast-like particles in the granulation tissue of inflamed colonic mucosa. Biotinylated ASCA also stained lymphocytes and polymorphonuclear cells infiltrating inflamed intestine. Monocytes in epithelioid granulomas of colon with Crohn's disease were also stained. Polymorphonuclear leukocytes in peripheral blood were also stained with biotinylated ASCA. The antigens reactive to ASCA among heat-extracted, non-heat-extracted yeast antigens, and human leukocyte extract differed. The findings of cross-reactivity of polymorphonuclear leukocytes with S. cerevisiae antigen and the presence of S. cerevisiae antigen in Crohn's disease granulomas suggest the possibility of involvement of S. cerevisiae in the pathogenesis of Crohn's disease.

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.

Gut mucosal response to food antigens in Crohn's disease

BACKGROUND

Food antigens may contribute to gut inflammation in Crohn's disease.

AIM

To assess in vivo sensitization to food antigens, ascertain whether sensitivity is gut specific, assess food sensitization in vitro, and correlate in vivo changes with histological and blood changes.

METHODS

Skin testing and rectal exposure to six food antigens (cereal, cabbage, citrus, milk, yeast and peanut) and control saline were assessed double-blind by immediate and 3.5-h laser Doppler blood flowmetry, and rectal biopsies were taken. Peripheral blood lymphocyte proliferation was measured in response to the same antigens.

RESULTS

Ten patients with Crohn's disease and 10 healthy controls were studied. Blood flow increased in 24 of 60 antigen sites in Crohn's disease patients and six of 60 antigen sites in controls (P < 0.0001) after 3.5 h. The Crohn's disease group demonstrated higher rectal blood flow than controls in response to all food antigens, and this was significantly different for the responses to yeast (P = 0.036) and citrus fruits (P = 0.038). Lymphocyte proliferation occurred in 32 of 60 tests in Crohn's disease patients and eight of 60 tests in controls (P < 0.0001). There were no skin responses. Submucosal oedema corresponded to increased mucosal flow.

CONCLUSIONS

Crohn's disease patients demonstrate in vivo and in vitro sensitization to food antigens, which is gut specific. Mucosal flowmetry allows the identification of sensitization to gut antigens.

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.

Diagnostic value of anti-Saccharomyces cerevisiae and antineutrophil cytoplasmic antibodies for inflammatory bowel disease: high prevalence in patients with celiac disease

Both celiac disease and inflammatory bowel disease (IBD) are characterized by chronic diarrhea and the presence of distinct (auto)antibodies. In the present study we wanted to determine the prevalence of serological markers for inflammatory bowel disease, i.e., perinuclear antineutrophil cytoplasmic antibodies (pANCA) and/or anti-Saccharomyces cerevisiae antibodies (ASCA), in 37 patients with biopsy-confirmed celiac disease (Marsh IIIb/c). The majority of the patients was positive for IgA (auto)antibodies typically associated with celiac disease, i.e., antiendomysium antibodies (EMA) (86.5%), antigliadin antibodies (AGA) (73%), and antirecombinant human tissue transglutaminase antibodies (rh-tTGA) (86.5%). Four patients with selective IgA deficiency could be identified by analyzing EMA, AGA, and rh-tTGA for the IgG isotype. The prevalence of pANCA and ASCA, markers that are used for IBD, was unexpectedly high in our cohort of patients with celiac disease: 8 patients were positive for pANCA (IgG) and 16 patients were positive for ASCA (IgG and/or IgA). These results indicate that the presence of pANCA or ASCA in the serum of patients with chronic diarrhea does not exclude celiac disease. A prospective study is required to determine whether pANCA and/or ASCA identify patients at risk for developing secondary autoimmune disease.

Assessment and relevance of enzyme-linked immunosorbent assay for antibodies to Saccharomyces cerevisiae in Australian patients with inflammatory bowel disease

The frequency of antibodies to Saccharomyces cerevisiae (ASCA) in Crohn's disease, ulcerative colitis and non-inflammatory bowel disease controls has been compared using two commercially available assays. The Medizym test resulted in sensitivity of 50% and specificity of 93% for Crohn's disease. The corresponding figures for the QUANTA Lite assay were 79% and 74%, respectively. Using ASCA and perinuclear antineutrophil cytoplasmic antibody (pANCA) in combination, the sensitivity and specificity of ASCA+/pANCA- for Crohn's disease using the Medizym kit were 50% and 100%, respectively, compared with 79% and 93% using QUANTA Lite. ASCA-/pANCA+ was 100% specific for ulcerative colitis with either assay. ASCA can be found in Australian patients with Crohn's disease at a similar frequency to that reported overseas.

Serological differentiation of inflammatory bowel diseases

OBJECTIVE

In order to shorten the diagnostic procedures simple serological tests with high diagnostic value for Crohn's disease and ulcerative colitis are required. The aim of this study was therefore to evaluate the diagnostic value of a newly developed assay for the determination of antibodies to mannan of Saccharomyces cerevisiae in combination with antibodies to antigens of exocrine pancreas, goblet cells, human neutrophils and tissue transglutaminase.

METHODS

Sera from 112 patients with Crohn's disease (82 confirmed and 30 suspected cases), 65 patients with ulcerative colitis, 13 patients with indeterminate colitis, 212 patients with other diseases and 250 healthy blood donors were tested for IgA and IgG antibodies to mannan of S. cerevisiae and IgA to tissue transglutaminase by enzyme-linked immunoassays. Endomysial IgA antibodies and antibodies to antigens of exocrine pancreas, goblet cells and human neutrophils were determined by indirect immunofluorescence. Sensitivity, specificity, positive and negative predictive values of antibodies to mannan of S. cerevisiae and different antibody combinations were determined regarding the diagnosis of Crohn's disease and ulcerative colitis.

RESULTS

Antibodies to mannan of S. cerevisiae were detected in 50% of confirmed and 27% of patients suspected of having Crohn's disease. Among patients who did not have Crohn's disease only those suffering from gluten-sensitive enteropathy and primary biliary cirrhosis exhibited antibodies to mannan of S. cerevisiae (14%, 6%). With respect to antibody positivity, antibodies to mannan of S. cerevisiae and/or antibodies to antigens of exocrine pancreas combined with tissue transglutaminase antibody negativity yields a sensitivity, specificity, positive and negative predictive value of 60%, 100%, 100% and 90%, respectively, regarding diagnosis of Crohn's disease.

CONCLUSIONS

Determination of antibodies to mannan of S. cerevisiae as a new marker for Crohn's disease is helpful for the differential diagnosis of inflammatory bowel disease. In combination with other established serological markers, antibodies to mannan of S. cerevisiae improve their diagnostic and predictive values considerably.

Detection of anti-Saccharomyces cerevisiae antibodies in Crohn's disease: is it a reliable diagnostic and prognostic marker?

BACKGROUND

In the past few years, serologic markers have been proposed in inflammatory bowel disease. Anti-Saccharomyces cerevisiae antibodies showed high specificity for Crohn's disease. A prognostic role for serology has also been hypothesised.

AIMS

To evaluate anti-Saccharomyces cerevisiae antibody distribution in an unselected Italian inflammatory bowel disease population. To analyse whether anti-Saccharomyces cerevisiae antibody status (positive/negative) and/or anti-Saccharomyces cerevisiae antibody titres are associated with clinical variables and outcome measures in Crohn's disease patients.

PATIENTS AND METHODS

A series of 299 inflammatory bowel disease patients were evaluated; serum samples were taken and a short clinical history was recorded. anti-Saccharomyces cerevisiae antibodies IgG enzyme-linked immunosorbent assay Medilab (Milan, Italy) kit was used in order to determine anti-Saccharomyces cerevisiae antibody status.

RESULTS

Sensitivity, specificity and likelihood ratio for positive test in the differential diagnosis of inflammatory bowel disease was 59%, 89%, 8.1, respectively. Clinical variables significantly associated with anti-Saccharomyces cerevisiae antibody status in logistic regression were found to be ileal location (p=0.01) and earlier age at diagnosis (p<0.01). Among ileal Crohn's disease patients, there was a trend in concordance between anti-Saccharomyces cerevisiae antibody titres and higher number of surgical procedures which was not statistically significant applying more complex statistics.

CONCLUSIONS

In an Italian inflammatory bowel disease population, anti-Saccharomyces cerevisiae antibodies status showed characteristics similar to those previously reported. Anti-Saccharomyces cerevisiae antibody positivity is associated with ileal involvement and with earlier onset of Crohn's disease.

Anti-Saccharomyces cerevisiae antibodies in inflammatory bowel disease: a family study

BACKGROUND

Antibodies to Saccharomyces cerevisiae (ASCA) have been described as specific markers for Crohn disease (CD). The reason for this disease specific generation of antibodies is not clear. Therefore, a family study was performed to evaluate whether the antibody production was due to genetic or environmental factors.

METHODS

Seventy-one patients with CD, 25 patients with ulcerative colitis (UC), their 282 first-degree relatives, and 32 spouses were included. As controls, 43 sera from healthy persons and 69 sera from patients with various autoimmune disorders were tested for ASCA by indirect immunofluorescence and ELISA.

RESULTS

ASCA were detected in 68% of the patients with CD and in none of the controls, UC patients included. Forty-eight (25%) first-degree relatives of patients with CD were ASCA-positive. ASCA status of relatives was not related to the fact whether these persons lived in the same household with the patients or not. However, one of the spouses of CD patients (4%) was found to be ASCA-positive and the antibody was also found in 5 (6%) of the relatives of UC patients.

CONCLUSIONS

ASCA are specific markers for CD. Since these antibodies are found in 25% of first-degree relatives, the generation of ASCA may be mainly related to genetic influences although environmental factors may also play a certain role.

Comparative study of ASCA (Anti-Saccharomyces cerevisiae antibody) assays in inflammatory bowel disease

BACKGROUND & AIMS

Anti-Saccharomyces cerevisiae antibody (ASCA) is a serologic marker associated with Crohn's disease (CD). Although there is still discussion on its clinical value, several companies each promote their own ASCA assay to be used in the gastroenterologist's practice at considerable expense. The aim of this study was to determine whether different ASCA assays agree sufficiently well for the results to be used interchangeably.

METHODS

Blood obtained from a large cohort of IBD patients with inflammatory bowel disease (IBD; 100 with CD, 100 with ulcerative colitis [UC]) and 178 controls (100 healthy blood donors and 78 patients with non-IBD diarrheal illnesses) was studied with 4 different ASCA assays. Sensitivity, specificity, and positive predictive value were compared. Agreement between assays was evaluated.

RESULTS

Sensitivity of ASCA for CD ranged between 41% and 76%. Sensitivity was inversely related to specificity and positive predictive value. Results correlated well overall (range = 0.54-0.90) and the different ROC curves showed good agreement. When recalculated cutoff points were used, interchangeability increased. However, large differences were seen when absolute values were compared.

CONCLUSIONS

A large range in sensitivities and specificities of ASCA for CD is seen with different ASCA assays, mainly as a consequence of the cutoff value chosen for each individual assay. Although agreement between and within assays is good, caution is important when absolute values are used. Standardization of ASCA measurements is greatly needed.