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

From ASCA breakthrough in Crohn's disease and Candida albicans research to thirty years of investigations about their meaning in human health

Anti-Saccharomyces cerevisiae antibodies (ASCA) are human antibodies that can be detected using an enzyme-linked immunosorbent assay involving a mannose polymer (mannan) extracted from the cell wall of the yeast S. cerevisiae. The ASCA test was developed in 1993 with the aim of differentiating the serological response in two forms of inflammatory bowel disease (IBD), Crohn's disease and ulcerative colitis. The test, which is based on the detection of anti-oligomannosidic antibodies, has been extensively performed worldwide and there have been hundreds of publications on ASCA. The earlier studies concerned the initial diagnostic indications of ASCA and investigations then extended to many human diseases, generally in association with studies on intestinal microorganisms and the interaction of the micro-mycobiome with the immune system. The more information accumulates, the more the mystery of the meaning of ASCA deepens. Many fundamental questions remain unanswered. These questions concern the heterogeneity of ASCA, the mechanisms of their generation and persistence, the existence of self-antigens, and the relationship between ASCA and inflammation and autoimmunity. This review aims to discuss the gray areas concerning the origin of ASCA from an analysis of the literature. Structured around glycobiology and the mannosylated antigens of S. cerevisiae and Candida albicans, this review will address these questions and will try to clarify some lines of thought. The importance of the questions relating to the pathophysiological significance of ASCA goes far beyond IBD, even though these diseases remain the preferred models for their understanding.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Clinical and Phenotypic Differences in Inflammatory Bowel Disease Among Arab and Jewish Children in Israel

BACKGROUND

Data on inflammatory bowel disease (IBD) phenotypes among the Arab population in Israel or in the neighboring Arab countries is scarce.

AIM

We aimed to assess differences in disease phenotype among Arab and Jewish children living in Israel.

METHODS

We performed a retrospective chart review of pediatric IBD cases, which were diagnosed at the Schneider Children's Medical Center and Ha'Emek Medical Center in Israel between 2000 and 2014. Demographic, clinical, and phenotypic variables were compared between Arabs and Jews from Eastern (Sephardic) and Western (Ashkenazi) origin.

RESULTS

Seventy-one Arab children with IBD were compared with 165 Ashkenazi and 158 Sephardic Jewish children. Age and gender did not differ between groups. Sephardic and Ashkenazi Jewish Crohn's disease (CD) patients had significantly more stenotic behavior (24 and 26 vs. 5%, p = 0.03) and less fistulzing perianal disease (15 and 11 vs. 31%, p = 0.014) compared with Arab patients. Arab children with ulcerative colitis (UC) had more severe disease at diagnosis compared to Sephardic and Ashkenazi Jews reflected by higher Pediatric UC Activity Index (45 vs. 35 and 35, respectively, p = 0.03). Arab patients had significantly lower proportion of anti-Saccharomyces cerevisiae antibodies positivity (in CD) and perinuclear anti-neutrophil cytoplasmic antibodies positivity (in UC) than both Sephardic and Ashkenazi Jewish children (23 vs. 53 and 65%, p = 0.002 and 35 vs. 60 and 75%, respectively, p = 0.002).

CONCLUSION

Arab and Jewish children with IBD differ in disease characteristics and severity. Whether genetic or environmental factors are the cause for these differences is yet to be determined.

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

BACKGROUND AND AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Inflammatory bowel disease serology in Asia and the West

AIM: To study serological antibodies in Caucasians and Asians, in health and inflammatory bowel disease (IBD), in Australia and Hong Kong (HK).

METHODS: Anti-glycan antibodies [anti-chitobioside (ACCA), anti-laminaribioside (ALCA)], and anti-mannobioside (AMCA), anti-Saccharomyces cervisiae (gASCA); and atypical perinuclear anti-neutrophil cytoplasmic antibody (pANCA) were tested in IBD patients, their unaffected relatives, and healthy controls in Australia and HK (China). Antibody status (positive or negative) and titre was compared between subjects of different geography, ethnicity and disease state.

RESULTS: Ninety subjects were evaluated: 21 Crohn’s disease (CD), 32 ulcerative colitis (UC), 29 healthy controls, and 8 IBD patient relatives. Forty eight subjects were Australian (29 Caucasian and 19 ethnic Han Chinese) and 42 were from HK (all Han Chinese). Caucasian CD patients had a significantly higher antibody prevalence of gASCA (67% vs 3%, P < 0.001), ALCA (44% vs 6%, P = 0.005), and AMCA (67% vs 15%, P = 0.002), whereas HK CD patients had a higher prevalence of only AMCA (58% vs 25%, P = 0.035), when compared with UC and healthy subjects in both countries. Caucasian CD had significantly higher gASCA prevalence (67% vs 0%, P < 0.001) and titre (median 59 vs 9, P = 0.002) than HK CD patients. Prevalence and titres of ALCA, ACCA and AMCA did not differ between CD in the two countries. Presence of at least one antibody was higher in Caucasian than HK CD patients (100% vs 58%, P = 0.045). pANCA did not differ between countries or ethnicity.

CONCLUSION: Serologic CD responses differ between HK Asian and Australian Caucasian patients. Different genetic, environmental or disease pathogenic factors may account for these differences.

Isolated active ileitis: is it a mild subtype of Crohn's disease?

BACKGROUND

Ileal intubation is being increasingly performed at colonoscopy and has in turn lead to an increasingly recognized subgroup of patients-those with mild terminal ileal inflammation, an entity that we have coined isolated active ileitis (IAI). The aims of this study were to define the natural history of IAI and determine if IAI shares a similar genetic and serologic profile with Crohn's disease (CD).

METHODS

Patients with IAI were identified from our institution's histopathology and endoscopy databases. Cases attended for repeat colonoscopy and blood were analyzed for the expression of antineutrophil cytoplasmic antibody, anti-OmpC, anti-Saccharomyces cerevisiae antigen (ASCA) IgA, ASCA IgG, and anti-CBir antibodies and NOD2 genotyping. Age and sex-matched healthy controls, CD, and UC cases were also recruited.

RESULTS

Sixty-three patients with IAI were recruited. There was no significant difference in the prevalence of antibodies between IAI cases and healthy controls for antineutrophil cytoplasmic antibody, OmpC, ASCA IgA, or ASCA IgG. The presence of all 5 antibodies was significantly higher in the CD group than the IAI group, P < 0.05. There were 28.6% of CD cases that carried one or more NOD2 variants, compared to 26.2% of the IAI cohort and 6.1% of healthy controls. Forty-three cases underwent follow-up ileocolonoscopy. Six of 43 cases (14%) had definite CD.

CONCLUSIONS

A majority of IAI cases developed persistent symptoms and terminal ileal abnormalities; however, only 14% developed classical, histological, or radiological features of CD. Although patients with IAI have a low level of seropositivity, similar to healthy controls, they do share an excess of NOD2 mutations with CD cases.

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.

Pathogenic agents in inflammatory bowel diseases

PURPOSE OF REVIEW

Infectious agents are still thought to be involved in the origin of inflammatory bowel disease. The focus in recent years has been more on Mycobacterium avium subsp paratuberculosis, adherent-invasive Escherichia coli or yeasts.

RECENT FINDINGS

A metaanalysis has shown a significant association of M. avium subsp paratuberculosis and Crohn's disease and a large randomized placebo-controlled trial reported an absence of sustained beneficial effects of combined antibiotic therapy on remission of active Crohn's disease. Adherent-invasive E. coli adhere via type 1 pili to carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6), abnormally expressed by intestinal epithelial cells in Crohn's disease patients. Both colonization of the ileal mucosa and stimulation of ileal epithelial cells by tumour necrosis factor-alpha induce overexpression of CEACAM6, leading to an amplification loop of colonization and inflammation. Anti-Saccharomyces cerevisiae mannan antibodies are the most prevalent serologic marker in Crohn's disease. Major oligomannose epitopes supporting antibody formation are expressed by Candida albicans in human tissues, suggesting that a loss of tolerance to C. albicans could lead to antibody formation in a subset of Crohn's disease patients who are genetically predisposed.

SUMMARY

M. avium subsp paratuberculosis, adherent-invasive E. coli and Candida are good candidates for an infectious aetiology of Crohn's disease on the basis of genetic susceptibility, which relates to impaired function in the defence against intracellular bacteria.

Detection of antisynthetic mannoside antibodies (ASigmaMA) reveals heterogeneity in the ASCA response of Crohn's disease patients and contributes to differential diagnosis, stratification, and prediction

OBJECTIVES

Anti-S. cerevisiae mannan antibodies (ASCA) are human antibodies associated with Crohn's disease (CD) reacting with Saccharomyces cerevisiae (S. cerevisiae) mannan polymer. As mannan is a complex and variable repertoire of oligomannoses acting as epitopes, we chemically synthesized (Sigma) two major oligomannose epitopes, Man alpha-1,3 Man alpha-1,2 Man (SigmaMan3) and Man alpha-1,3 Man alpha-1,2 Man alpha-1,2 Man (SigmaMan4), and then explored how antisynthetic mannoside antibodies (ASigmaMA) compare with ASCA as markers of CD.

METHODS

The study involved different cohorts of CD and ulcerative colitis (UC) patients and healthy controls who had been studied previously in several medical centers in Europe, the United States, and North Africa to determine the clinical value of ASCA in terms of differential diagnosis, evolution of indeterminate colitis (IC), and serotype-phenotype correlations. The comparison of ASigmaMA and ASCA included a total of 1,365 subjects: 772 CD, 261 UC, 43 IC, and 289 controls.

RESULTS

The specificity of ASigmaMA was similar to that of ASCA (89% vs 93%), although the sensitivity was lower (38% vs 55%). Unexpectedly, 24% of the CD patients who were negative for ASCA and/or other CD-associated serologic markers were positive for ASigmaMA. ASigmaMA were associated with colonic involvement in CD (odds ratio [OR] 1.609, 95% confidence interval [CI] 1.033-2.506, P = 0.03) and were 100% predictive of CD in patients with IC.

CONCLUSIONS

ASigmaMA reveal the heterogeneity of the antioligomannose antibody response in CD patients and increase the sensitivity of CD diagnosis when combined with ASCA. The subset of ASCA-negative CD patients diagnosed by ASigmaMA had preferentially a colonic involvement, which confirms the high predictive value of ASigmaMA for determining IC evolution toward CD.

Advances in studies on relation between inflammatory bowel disease and immunity

Inflammatory bowel disease is a chronic inflammatory disease of the gastrointestinal tract. Its main clinical manifestations are abdominal pain and diarrhea. Its etiology is complicated. Immune system is very important. Following factors, such as intestinal environment, immune cells, human leukocyte antigens, antibodies, anti- laminaribioside antibody, anti-chitobioside antibody IgA, cytokines, cell adhesion molecules, NO and NF-κB, play a key role in the pathogenesis of inflammatory bowel disease. Inflammatory bowel disease is related to all these factors. This paper reviews the possible role of these immune factors in the pathogenesis of inflammatory bowel disease.