The presence of anti-neutrophil antibodies reflects clinical and genetic heterogeneity within inflammatory bowel disease

Ulcerative colitis: Recent advances in the understanding of disease pathogenesis

Inflammatory bowel diseases are common, complex, immune-mediated conditions with a sharply rising global prevalence. While major advances since 2000 have provided strong mechanistic clues implicating a de-regulation in the normal interaction among host genetics, immunity, microbiome, and the environment, more recent progress has generated entirely new hypotheses and also further refined older disease concepts. In this review, we focus specifically on these novel developments in the pathogenesis of ulcerative colitis.

Antineutrophil antibodies define clinical and genetic subgroups in primary sclerosing cholangitis

BACKGROUND & AIMS

The strongest genetic risk factors in primary sclerosing cholangitis (PSC) are encoded in the HLA complex. Antineutrophil cytoplasmic antibodies (ANCA) have been reported in up to 94% of PSC patients, but their clinical significance and immunogenetic basis are ill defined. We aimed to characterize clinical and genetic associations of ANCA in PSC.

METHODS

Antineutrophil cytoplasmic antibodies were analysed with indirect immunofluorescence in 241 Norwegian PSC patients. HLA-B and HLA-DRB1 genotyping was performed in the patients and in 368 healthy controls. Data on perinuclear ANCA (pANCA) and HLA-DRB1 were available from 274 ulcerative colitis (UC) patients without known liver disease.

RESULTS

Antineutrophil cytoplasmic antibodies were found in 193 (80%) of the PSC patients, with pANCA in 169 (70%). ANCA-positive patients were younger than ANCA negative at diagnosis of PSC and had a lower frequency of biliary cancer (9% vs 19%, P=.047). There were no differences between PSC patients with and without inflammatory bowel disease. Genetically, the strong PSC risk factors HLA-B*08 (frequency in healthy 13%) and DRB1*03 (14%) were more prevalent in ANCA-positive than -negative patients (43% vs 25%, P=.0012 and 43% vs 25%, P=.0015 respectively). The results were similar when restricting the analysis to pANCA-positive patients. In UC patients without liver disease, HLA-DRB1*03 was more prevalent in pANCA-positive compared with -negative patients (P=.03).

CONCLUSIONS

Antineutrophil cytoplasmic antibodies identified PSC patients with particular clinical and genetic characteristics, suggesting that ANCA may mark a clinically relevant pathogenetic subgroup in the PSC-UC disease spectrum.

Serum anti-glycan antibody biomarkers for inflammatory bowel disease diagnosis and progression: a systematic review and meta-analysis

BACKGROUND

Anti-glycan antibody serologic markers may serve as a useful adjunct in the diagnosis/prognosis of inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC). This meta-analysis/systemic review aimed to evaluate the diagnostic value, as well as the association of anti-glycan biomarkers with IBD susceptible gene variants, disease complications, and the need for surgery in IBD.

METHODS

The diagnostic odds ratio (DOR), 95% confidence interval (CI), and sensitivity/specificity were used to compare the diagnostic value of individual and combinations of anti-glycan markers and their association with disease course (complication and/or need for surgery).

RESULTS

Fourteen studies were included in the systemic review and nine in the meta-analysis. Individually, anti-Saccharomyces cervisiae antibodies (ASCA) had the highest DOR for differentiating IBD from healthy (DOR 21.1; 1.8-247.3; two studies), and CD from UC (DOR 10.2; CI 7.7-13.7; seven studies). For combination of ≥2 markers, the DOR was 2.8 (CI 2.2-3.6; two studies) for CD-related surgery, higher than any individual marker, while the DOR for differentiating CD from UC was 10.2 (CI 5.6-18.5; three studies) and for complication was 2.8 (CI 2.2-3.7; two studies), similar to individual markers.

CONCLUSIONS

ASCA had the highest diagnostic value among individual anti-glycan markers. While anti-chitobioside carbohydrate antibody (ACCA) had the highest association with complications, ASCA and ACCA associated equally with the need for surgery. Although in most individual studies the combination of ≥2 markers had a better diagnostic value as well as higher association with complications and need for surgery, we found the combination performing slightly better than any individual marker in our meta-analysis.

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.

Efficacy and safety of mesalamine suppositories for treatment of ulcerative proctitis in children and adolescents

BACKGROUND

Treatment of ulcerative proctitis has not been well studied in pediatric populations. We conducted an open-label trial to evaluate the clinical efficacy of a mesalamine suppository (500 mg) to treat pediatric patients with mild to moderate ulcerative proctitis.

METHODS

Pediatric patients (5-17 years of age) with ulcerative proctitis were enrolled for baseline evaluations, including a flexible sigmoidoscopic (or colonoscopic) assessment with biopsies performed at study entry. Eligible patients were started on mesalamine suppositories (500 mg) at bedtime. Two follow-up visits were scheduled after 3 and 6 weeks of treatment. The dose could be increased to 500 mg twice daily at the week 3 follow-up visit if deemed appropriate by the investigator based on the Disease Activity Index (DAI) assessment. The primary outcome measure was a DAI derived from a composite score of stool frequency, urgency of defecation, rectal bleeding, and general well-being.

RESULTS

Forty-nine patients were included in the intent-to-treat analysis. The mean DAI value decreased from 5.5 at baseline to 1.6 and 1.5 at weeks 3 and 6, respectively (P < 0.0001). Only 4 patients had their dose increased to 500 mg twice daily at week 3. Forty-one patients experienced at least one adverse event, most of which were deemed mild and unrelated to study therapy. The most common treatment-emergent adverse events were gastrointestinal (n = 30, 61.2%).

CONCLUSIONS

This study showed that a daily bedtime dose of a 500 mg mesalamine suppository is safe and efficacious in children with ulcerative proctitis.

Multivariate modeling identifies neutrophil- and Th17-related factors as differential serum biomarkers of chronic murine colitis

Background

Diagnosis of chronic intestinal inflammation, which characterizes inflammatory bowel disease (IBD), along with prediction of disease state is hindered by the availability of predictive serum biomarker. Serum biomarkers predictive of disease state will improve trials for therapeutic intervention, and disease monitoring, particularly in genetically susceptible individuals. Chronic inflammation during IBD is considered distinct from infectious intestinal inflammation thereby requiring biomarkers to provide differential diagnosis. To address whether differential serum biomarkers could be identified in murine models of colitis, immunological profiles from both chronic spontaneous and acute infectious colitis were compared and predictive serum biomarkers identified via multivariate modeling.

Methodology/Principal Findings

Discriminatory multivariate modeling of 23 cytokines plus chlorotyrosine and nitrotyrosine (protein adducts from reactive nitrogen species and hypochlorite) in serum and tissue from two murine models of colitis was performed to identify disease-associated biomarkers. Acute C. rodentium-induced colitis in C57BL/6J mice and chronic spontaneous Helicobacter-dependent colitis in TLR4^−/− x IL-10^−/− mice were utilized for evaluation. Colon profiles of both colitis models were nearly identical with chemokines, neutrophil- and Th17-related factors highly associated with intestinal disease. In acute colitis, discriminatory disease-associated serum factors were not those identified in the colon. In contrast, the discriminatory predictive serum factors for chronic colitis were neutrophil- and Th17-related factors (KC, IL-12/23p40, IL-17, G-CSF, and chlorotyrosine) that were also elevated in colon tissue. Chronic colitis serum biomarkers were specific to chronic colitis as they were not discriminatory for acute colitis.

Conclusions/Significance

Immunological profiling revealed strikingly similar colon profiles, yet distinctly different serum profiles for acute and chronic colitis. Neutrophil- and Th17-related factors were identified as predictive serum biomarkers of chronic colitis, but not acute colitis, despite their presence in colitic tissue of both diseases thereby demonstrating the utility of mathematical modeling for identifying disease-associated serum biomarkers.

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.

Predictive value of serologic markers in a population-based Norwegian cohort with inflammatory bowel disease

BACKGROUND

Perinuclear antineutrophil cytoplasmic antibodies (pANCA) and anti-Saccharomyces cerevisiae antibodies (ASCA) are proposed to be specific markers for ulcerative colitis (UC) and Crohn's disease (CD). Their prevalence and relationship to disease phenotype and outcome in unselected cohorts of patients with inflammatory bowel disease (IBD), however, is largely unclear. We studied the prevalence of these serologic markers in a population-based IBD cohort 10 years after diagnosis, and examined whether their presence could be related to distinct subgroups and outcome of disease.

METHODS

Of 685 living IBD patients, 620 met for a 10-year follow-up, of whom 526 (UC, n = 357 and CD, n = 169) participated in this study.

RESULTS

Twenty-seven percent (n = 46) of CD patients were ASCA-positive and 31% (n = 109) of UC patients were pANCA-positive. Positive ASCA was more frequent in CD patients with stricturing (P = 0.003) or penetrating (P = 0.012) complications than in those with inflammatory behavior at diagnosis. Moreover, the presence of ASCA was associated with an at least twice higher risk of evolving more severe disease behavior during follow-up (P < 0.001). In UC, pANCA expression was related to female gender (P = 0.005) and the use of azathioprine (P < 0.001), and in CD, to colon-limited disease and age >/=40 years at diagnosis (P = 0.009 and P = 0.001, respectively).

CONCLUSIONS

The prevalence of ASCA in CD and pANCA in UC appears markedly lower than in referral-based populations. Even with the low prevalence, our study gives further support to the role of ASCA and pANCA as markers for distinct phenotype and outcome of disease.

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.

(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.

Seroreactivity to microbial components in Crohn's disease is associated with ileal involvement, noninflammatory disease behavior and NOD2/CARD15 genotype, but not with risk for surgery in a Hungarian cohort of IBD patients

BACKGROUND

Antibodies directed against Saccharomyces cerevisiae (ASCA), perinuclear components of neutrophils (pANCA), and porin protein C of Escherichia coli (anti-OmpC) are reported to be associated with disease phenotype and may be of diagnostic importance in inflammatory bowel disease (IBD). Since limited data are available from Eastern Europe, we assessed the above antibodies in Hungarian IBD patients.

METHODS

In all, 653 well-characterized, unrelated consecutive IBD patients (Crohn's disease [CD]: 558, m/f: 263/295, duration: 8.1 +/- 10.7 years; ulcerative colitis [UC]: 95, m/f: 44/51, duration: 8.9 +/- 9.8 years) and 100 healthy subjects were investigated. Sera were assayed for anti-Omp and ASCA by enzyme-linked immunosorbent assay (ELISA) and ANCA by indirect immunofluorescence assay (IIF). TLR4 and NOD2/CARD15 variants were tested by polymerase chain reaction/restriction fragment length polymorphism (PCR-RFLP). Detailed clinical phenotypes were determined by reviewing the medical charts.

RESULTS

Anti-Omp, ASCA, and atypical pANCA antibodies were present in 31.2%, 59.3%, and 13.8% of CD, 24.2%, 13.7%, and 48.5% of UC patients, and in 20%, 16%, and 5.6% of controls, respectively. ASCA and anti-Omp positivity were associated with increased risk for CD (odds ratio [OR](ASCA) = 7.65, 95% confidence interval [CI]: 4.37-13.4; OR(Omp) = 1.81, 95% CI: 1.08-3.05). In a logistic regression analysis, anti-Omp and ASCA were independently associated with ileal and noninflammatory disease, but not with a risk for surgery or response to steroids or infliximab. A serology dosage effect was also observed. ASCA and anti-Omp antibodies were associated with NOD2/CARD15, in addition to a gene dosage effect. No associations were found in UC.

CONCLUSIONS

Serological markers were useful in the differentiation between CD and UC in an Eastern European IBD cohort. Reactivity to microbial components was associated with disease phenotype and NOD2/CARD15 genotype, further supporting the role of altered microbial sensing in the pathogenesis of CD.

Perinuclear anti-neutrophil cytoplasmic antibodies (p-anca) in chronic ulcerative colitis: Experience in a Mexican institution

AIM: To assess the prevalence and clinical value of p-ANCA in a sample of Mexican ulcerative colitis (UC) patients.

METHODS: In a prospective, IRB-approved protocol, p-ANCA was determined in 80 patients with UC (mean age, 32 ± 12.9 years). The severity and extension of disease were determined by clinical methods, searching a statistical association with p-ANCA status.

RESULTS: p-ANCA were detected in 41 (51%) patients. Severity of disease was the only clinical variable statistically associated with their presence (P < 0.0001; OR = 9; CI 95% = 3.2-24.7).

CONCLUSION: The prevalence of p-ANCA was similar to that reported in other countries. Their presence was associated to UC severity, but offered no more information than the obtained by clinical methods.

Association of the HLA-DRB1*0701 allele with perinuclear anti-neutrophil cytoplasmatic antibodies in Mexican patients with severe ulcerative colitis

AIM: To determine the association between the HLA-DRB1 alleles and perinuclear anti-neutrophil cytoplasmatic antibodies (p-ANCA) positive in Mexican patients with ulcerative colitis (UC).

METHODS: Ninety Mexican mestizo patients (45 females) with UC, confirmed by biopsy, were studied. High resolution HLA typing was performed by PCR-SSO reverse dot blot and PCR-SSP. Molecular typing techniques were applied to define HLA-DRB1 alleles. Enzyme-linked immunosorbent assay and immunofluorescence techniques were used to detect p-ANCA.

RESULTS: Forty-eight (53%) UC patients were positive for p-ANCA by ELISA and IF. We found that p-ANCA-positive UC patients had a significantly increased frequency of HLA-DR7 compared with p-ANCA-negative controls (22% vs 5.1%; pC = 0.02, OR = 5.2, CI 95%: 1.06-37.82). Disease activity was scored as severe in 20 patients, moderate in 8, mild in 14 and no activity in the remaining 38 patients according to the Truelove and Witts criteria. Subgroup analysis showed a significantly increased frequency of the HLA-DRB1*07 allele in 15 of 20 UC patients with severe activity of UC and p-ANCA positivity [100% vs 0%; pC = 0.0000001; OR = 35]. No significant differences were found between p-ANCA positive patients, HLA-DR alleles and other clinical features such as extraintestinal manifestations, proctocolectomy and extension.

CONCLUSION: The HLA-DRB1*07 is associated with p-ANCA positive UC Mexican patients.

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.

The diagnostic accuracy of serologic markers in children with IBD: the West Virginia experience

GOAL

To assess the sensitivity/specificity of the serologic markers: perinuclear antineutrophil cytoplasmic antibody (pANCA) and anti-saccharomyces cerevisiae antibody (ASCA) in children diagnosed with inflammatory bowel disease (IBD), living in West Virginia.

BACKGROUND

In recent years, serologic markers have been used to differentiate between CD and UC diseases in children. The clinical usefulness of these markers in children was restricted by their low sensitivity and specificity. Racial and ethnic diversity may alter the accuracy of these markers in children. The demographic homogeneity of the West Virginia population may offer a better clinical setup to reassess the utility of those markers in children with IBD.

STUDY

A retrospective analysis of all the charts of children diagnosed with IBD was performed at the gastroenterology clinics of Marshall University, Huntington, WV; and West Virginia University, Charleston Division, Charleston, WV. The diagnosis of IBD was established according to clinical, radiologic, and endoscopic data. Laboratory data and serum markers were recorded, and their accuracy to diagnose UC or CD was assessed.

RESULTS

A total of 101 charts were reviewed, of which only 90 (89%) included serologic markers and were considered for further analysis. Disease distribution included: UC-41, CD-44, and indeterminate colitis (IC)-7 (2 patients changed diagnosis after colectomy). Serum antibody pANCA had a sensitivity of 73% and specificity of 84% for UC, but only 16% and 35% for CD, respectively. Serum antibody ASCA had a sensitivity of 58% and specificity of 92% for CD, but only 7% and 49% for UC, respectively. The outer membrane porin to Escherichia coli antibody (anti-OmpC) was available in 54 (59%) children and demonstrated a very poor sensitivity for both diseases (sensitivity<11%).

CONCLUSION

Despite our homogeneous patient population, pANCA and ASCA antibodies had an inadequate sensitivity/specificity for children with UC or CD. Those antibodies were not useful for our small number of patients with IC.

HLA-DRB1 alleles may influence disease phenotype in patients with inflammatory bowel disease: a critical reappraisal with review of the literature

PURPOSE

The HLA region has been implicated in determining the disease susceptibility or the clinical phenotype of inflammatory bowel disease. The aim of this study was to assess the relation between HLA-DRB1 alleles with the clinical features of Crohn's disease and ulcerative colitis and the presence of anti-neutrophil cytoplasmic and anti-Saccharomyces cerevisiae antibodies.

METHODS

Blood samples were obtained from 102 Crohn's disease patients, 114 ulcerative colitis patients, and 264 unrelated healthy controls. Anti-neutrophil cytoplasmics were detected by a standard immunofluorescence method, and anti-Saccharomyces cerevisiaes were examined by an enzyme-linked immunosorbent assay immunoglobulin G/immunoglobulin A commercial assay. HLA-DRB1 typing of 26 alleles was performed by polymerase chain reaction sequence-specific primes. Patients were phenotyped according to gender, disease location, extent, and behavior, surgical resection, need of steroid, and anti-neutrophil cytoplasmic/anti-Saccharomyces cerevisiae status.

RESULTS

As a whole, after applying Bonferroni's correction for multiple comparisons, no significant association of HLA-DRB1 alleles with Crohn's disease or ulcerative colitis was found. After stratifying HLA-DRB1 alleles by clinical phenotypes of patients with ulcerative colitis, an excess of DRB1*1309*1320*1325*1329 allele (DR13) was found in conjunction with pancolitis (P < 0.0001), surgical resection (P < 0.0003), and extraintestinal manifestations (P < 0.0001). In Crohn's disease patients, an excess of DRB1*0304*0305*0307*0309 allele (DR3) was found in those with colonic disease (P < 0.0001) and patients with extraintestinal manifestations (P = 0.0003). This statistical association, however, emerged in only 3 of 114 patients with ulcerative colitis and in 3 of 102 patients with Crohn's disease. We found no association with the presence of anti-Saccharomyces cerevisiae or anti-neutrophil cytoplasmic.

CONCLUSIONS

Some clinical features of Crohn's disease and ulcerative colitis may be influenced by specific HLA-DR alleles; in particular, in ulcerative colitis some alleles appear to segregate with more aggressive disease, whereas in Crohn's disease different alleles cosegregate in patients with colonic disease and extraintestinal manifestations.

Sero-reactivity to microbial components in Crohn's disease is associated with disease severity and progression, but not NOD2/CARD15 genotype

BACKGROUND AND AIMS

Antibodies directed against the porin protein C of Escherichia coli (anti-OmpC) and Pseudomonas fluorescens (anti-I2) have recently been described in Crohn's disease (CD). Those directed against Saccharomyces cerevisiae (ASCA) and the perinuclear component of neutrophils (pANCA) have been more widely studied and may be of diagnostic importance. We aimed to assess the frequency of anti-OmpC, anti-I2, ASCA, and pANCA, in an independent Scottish CD cohort, establish phenotypic associations, and compare with a U.S. cohort.

METHODS

One hundred and forty-two well-characterized CD patients (76 females, median age 39 yr (17-88)) were studied. CD was classified by the Vienna classification. Sera were assayed for anti-OmpC, anti-I2, ASCA, and pANCA. Allele specific primers were used for NOD2/CARD15 genotyping.

RESULTS

Anti-OmpC, anti-I2, ASCA, and pANCA were present in sera from 37%, 52%, 39%, and 14% of CD patients, respectively. Multivariate analysis demonstrated independent associations of anti-OmpC to be progression of disease type (p= 0.005) and long disease duration (p= 0.002), and those of anti-I2 to be long disease duration (p= 0.002) and the need for surgery (p= 0.033). ASCA were associated with disease progression (p < 0.001). When the presence and magnitude of all antibody responses were considered, reactivity to microbial components was associated with long disease duration (p < 0.001), progression of disease type (p < 0.001), penetrating disease (p= 0.008), small bowel disease (p < 0.02), and the need for surgery (p < 0.001). There was no association of antibody status to NOD2/CARD15 genotype.

CONCLUSION

Reactivity to microbial components is associated with severe CD characterized by small bowel involvement, frequent disease progression, longer disease duration, and greater need for intestinal surgery.

Anti-Saccharomyces cerevisiae antibodies (ASCA) in Crohn's disease are associated with disease severity but not NOD2/CARD15 mutations

Anti-Saccharomyces cerevisiae antibodies (ASCAs) have been proposed as serological markers, which may differentiate Crohn's disease (CD) from ulcerative colitis (UC) and predict disease phenotype. Their importance in pathogenesis is unproven. We investigated the relationship between ASCAs, disease phenotype and NOD2/CARD15 genotype in CD and whether ASCAs were related to antibodies to other fungal proteins. Serum from 228 patients [143 CD, 75 UC, 10 with indeterminate colitis (IC)] and 78 healthy controls (HC) were assayed for ASCA. Antibodies (IgA, IgG) to other fungal proteins (Fusarium species ATC20334, Mycoprotein) were measured in the same samples using an in-house enzyme-linked immunosorbent assay (ELISA) assay. ASCAs were present in 57% of CD, 19% of UC, 30% of IC and 8% of HCs. ASCA-positive status was a predictor for CD with sensitivity of 57%, specificity of 87%, positive predictive value of 78% and negative predictive value of 68%. ASCA was associated with proximal (gastroduodenal and small bowel involvement) rather than purely colonic disease (P < 0.001) and with a more severe disease phenotype and requirement for surgery over a median follow-up time of 9 years (P < 0.0001). No associations with NOD2/CARD15 mutations were seen. There was no association between ASCA and antibodies to MP (IgA or IgG). These data implicate ASCA as a specific marker of disease location and progression in CD, emphasizing the heterogeneity within IBD.

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.

Serological markers for prediction of response to anti-tumor necrosis factor treatment in Crohn's disease

OBJECTIVES

The use of monoclonal anti-tumor necrosis factor (TNF) antibodies (infliximab, Remicade) is a new therapeutic approach for severe refractory luminal or fistulizing, Crohn's disease (CD). However, up to 30% of patients do not respond to this treatment. So far, no parameters predictive of response to anti-TNF have been identified. Our aim was to determine whether serological markers ASCA (anti-Saccharomyces cerevisiae antibodies) or pANCA (perinuclear antineutrophil cytoplasmic antibodies) could identify Crohn's patients likely to benefit from anti-TNF therapy.

METHODS

Serum samples of 279 CD patients were analyzed for ASCA and pANCA before anti-TNF therapy. A blinded physician determined clinical response at week 4 (refractory luminal CD) or week 10 (fistulizing CD) after the first infusion of infliximab (5 mg/kg).

RESULTS

Overall, there was no relationship between ASCA or pANCA and response to therapy. However, lower response rates were observed for patients with refractory intestinal disease carrying the pANCA+/ASCA- combination, although this lacked significance (p = 0.067).

CONCLUSIONS

In this cohort of infliximab-treated patients, neither ASCA nor pANCA could predict response to treatment. However, the combination pANCA+/ASCA- might warrant further investigation for its value in predicting nonresponse in patients with refractory luminal disease.

Behaviour of Crohn's disease according to the Vienna classification: changing pattern over the course of the disease

BACKGROUND

Crohn's disease is a heterogeneous disorder with both a genetic and environmental aetiology. Clinical classifications of the disease, such as the newly proposed Vienna classification, may help to define subgroups of patients suitable for studying the influence of specific genetic or environmental factors.

AIM

To assess the stability over the course of the disease of its location and behaviour, as determined according to the Vienna classification.

PATIENTS AND METHODS

The notes of 297 Crohn's disease patients regularly followed up at our institution were carefully reviewed retrospectively. The behaviour and location of the disease according to the Vienna classification were determined at diagnosis and after 1, 3, 5, 10, 15, 20, and 25 years of follow up. The proportions of the different behaviours and locations of the disease were calculated at these time points. A statistical analysis of the evolution of these characteristics over 10 years was performed on a subgroup of 125 patients with at least 10 years of follow up. The influence of age at diagnosis on location and behaviour of the disease was assessed as well as the influence of location on the behaviour of the disease.

RESULTS

The location of the disease remained relatively stable over the course of the disease. Although the proportion of patients who had a change in disease location became statistically significant after five years (p=0.01), over 10 years only 15.9% of patients had a change in location (p<0.001). We observed a more rapid and prominent change in disease behaviour, which was already statistically significant after one year (p=0.04). Over 10 years, 45.9% of patients had a change in disease behaviour (p<0.0001). The most prominent change was from non-stricturing non-penetrating disease to either stricturing (27.1%; p<0.0001) or penetrating (29.4%; p<0.0001) disease. Age at diagnosis had no influence on either location or behaviour of disease. Ileal Crohn's disease was more often stricturing, and colonic or ileocolonic Crohn's disease was more often penetrating: this was already the case at diagnosis and became more prominent after 10 years (p<0.05).

CONCLUSIONS

Location of Crohn's disease, as defined by the Vienna classification, is a relatively stable phenotype which seems suitable for phenotype-genotype analyses. Behaviour of Crohn's disease according to the Vienna classification varies dramatically over the course of the disease and cannot be used in phenotype-genotype analyses. The potential influence of genes on the behaviour of Crohn's disease should be studied in subgroups of patients defined by their disease behaviour after a fixed duration of disease.

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.

Anti-Saccharomyces cerevisiae antibodies (ASCA), phenotypes of IBD, and intestinal permeability: a study in IBD families

BACKGROUND

Serologic markers anti-Saccharomyces cerevisiae antibodies (ASCA) and antineutrophil cytoplasmic antibodies with perinuclear staining (pANCA) have been proposed to study the immunopathogenesis of IBD. Their measurement may allow better phenotyping of the disease and the detection of subclinical disease.

AIMS

To test the hypothesis that serological markers identify an immunologic trait related to disease susceptibility. We also wanted to test the hypothesis that ASCA is a marker related to abnormal tissue permeation by common antigens.

METHODS

We studied the prevalence of pANCA and ASCA in a large cohort of sporadic and familial inflammatory bowel diseases and their unaffected relatives and spouses. Kinetics of ASCA was studied and the relationship between ASCA and 51Cr-EDTA intestinal permeation was investigated.

RESULTS

ASCA was associated with sporadic Crohn's disease (CD) (63%), with Crohn's patients belonging to pure CD families (62%) and also with their unaffected family members (21%). pANCA was associated with UC (58%). The prevalence of ASCA in CD patients belonging to mixed families was strikingly low (33%). ASCA was a stable marker throughout the disease and was not related to an increased small intestinal permeability.

CONCLUSION

ASCA is strongly associated with familial CD in Belgium, and 21% of healthy family members also display the marker. The association is much weaker in patients belonging to mixed families. ASCA is a stable marker and is not a secondary phenomenon due to increased intestinal permeability.

Antineutrophil cytoplasmic antibodies in inflammatory bowel disease: clinical role and review of the literature

PURPOSE

Perinuclear antineutrophil cytoplasmic antibodies have been found consistently in patients with ulcerative colitis; however, their pathogenetic and clinical role is still uncertain. In this study we tested the prevalence of perinuclear antineutrophil cytoplasmic antibodies in a large population of patients with ulcerative colitis and Crohn's disease, with particular attention to the possible correlation with clinical features.

METHODS

Perinuclear antineutrophil cytoplasmic antibody reactivity was investigated with indirect immunofluorescence in 279 patients with ulcerative colitis, 110 patients with Crohn's disease, and 252 unrelated healthy subjects.

RESULTS

Perinuclear antineutrophil cytoplasmic antibodies were found in 84 of 279 patients with ulcerative colitis (30 percent), 10 of 110 patients with Crohn's disease (9 percent), and 2 of 252 healthy subjects (<1 percent; P < 0.001), respectively. Perinuclear antineutrophil cytoplasmic antibodies were significantly more frequent in patients with ulcerative colitis with higher relapse rate (43 vs. 27 percent; P < 0.002), and patients with Crohn's disease with colitis (27 vs. 2.5 percent; P < 0.0003). Perinuclear antineutrophil cytoplasmic antibodies were also significantly less frequent in patients with ulcerative colitis in remission (18 vs. 34 percent; P < 0.0025).

CONCLUSIONS

In this study we confirm the relative specificity of perinuclear antineutrophil cytoplasmic antibodies, either for ulcerative colitis or for Crohn's disease involving the colon. Perinuclear antineutrophil cytoplasmic antibodies were more frequently found in patients with ulcerative colitis with a more aggressive clinical behavior; however, their presence had a limited value in identifying homogeneous subgroups of patients in our population.

Colonic bacteria express an ulcerative colitis pANCA-related protein epitope

Bacteria are a suspected pathogenic factor in inflammatory bowel disease, but the identity of the relevant microbial species remains unresolved. The pANCA autoantibody is associated with most cases of ulcerative colitis (UC) and hence reflects an immune response associated with the disease process. This study addresses the hypothesis that pANCA identifies an antigen(s) expressed by bacteria resident in the human colonic mucosa. Libraries of colonic bacteria were generated using aerobic and anaerobic microbiologic culture conditions, and bacterial pools and clonal isolates were evaluated for cross-reactive antigens by immunoblot analysis using the pANCA monoclonal antibody Fab 5-3. Two major species of proteins immunoreactive to pANCA monoclonal antibodies were detected in bacteria from the anaerobic libraries. Colony isolates of the expressing bacteria were identified as Bacteroides caccae and Escherichia coli. Isolation and partial sequencing of the B. caccae antigen identified a 100-kDa protein without database homologous sequences. The E. coli protein was biochemically and genetically identified as the outer membrane porin OmpC. Enzyme-linked immunosorbent assay with human sera demonstrated elevated immunoglobulin G anti-OmpC in UC patients compared to healthy controls. These findings demonstrate that a pANCA monoclonal antibody detects a recurrent protein epitope expressed by colonic bacteria and implicates colonic bacterial proteins as a target of the disease-associated immune response.

A simple classification of Crohn's disease: report of the Working Party for the World Congresses of Gastroenterology, Vienna 1998

Crohn's disease is a heterogeneous entity. Previous attempts of classification have been based primarily on anatomic location and behavior of disease. However, no uniform definition of patient subgroups has yet achieved broad acceptance. The aim of this international Working Party was to develop a simple classification of Crohn's disease based on objective variables. Eight outcome-related variables relevant to Crohn's disease were identified and stepwise evaluated in 413 consecutive cases, a database survey, and by clinical considerations. Allocation of variables was conducted with well-defined Crohn's disease populations from Europe and North America. Cross-table analyses were performed by chi-square testing. Three variables were finally elected: Age at Diagnosis [below 40 years (A1), equal to or above 40 years (A2)], Location [terminal ileum (L1), colon (L2), ileocolon (L3), upper gastrointestinal (L4)], and Behavior [nonstricturing nonpenetrating (B1), stricturing (B2), penetrating (B3)]. The allocation of patients to these 24 subgroups proved feasible and resulted in specific disease clusters. Cross-table analyses revealed associations between Age at Diagnosis and Location, and between Behavior and Location (all p < 0.001). The Vienna classification of Crohn's disease provides distinct definitions to categorize Crohn's patients into 24 subgroups. Operational guidelines should be used for the characterization of patients in clinical trials as well as for correlation of particular phenotypes with putative biologic markers or environmental factors.

Identification of a novel mycobacterial histone H1 homologue (HupB) as an antigenic target of pANCA monoclonal antibody and serum immunoglobulin A from patients with Crohn's disease

pANCA is a marker antibody associated with inflammatory bowel disease (IBD), including most patients with ulcerative colitis and a subset with Crohn's disease. This study addressed the hypothesis that pANCA reacts with an antigen(s) of microbial agents potentially relevant to IBD pathogenesis. Using a pANCA monoclonal antibody, we have previously identified the C-terminal basic random-coil domain of histone H1 as a pANCA autoantigen. BLAST analysis of the peptide databases revealed H1 epitope homologues in open reading frames of the Mycobacterium tuberculosis genome. Western analysis of extracts from six mycobacterial species directly demonstrated reactivity to a single, conserved approximately 32-kDa protein. Direct protein sequencing, followed by gene cloning, revealed a novel 214-amino-acid protein, an iron-regulated protein recently termed HupB. Sequence analysis demonstrated its homology with the mammalian histone H1 gene family, and recombinant protein expression confirmed its reactivity with the 5-3 pANCA monoclonal antibody. Binding activity of patient serum immunoglobulin G (IgG) to HupB did not correlate with reactivity to histone H1 or pANCA, indicating the complex character of the pANCA antigen. However, anti-HupB IgA was strongly associated with Crohn's disease (P < 0.001). These findings indicate that the 5-3 pANCA monoclonal antibody detects a structural domain recurrent among mycobacteria and cross-reactive with a DNA-binding domain of histone H1. The association of HupB-binding serum IgA with IBD provides new evidence for the association of a mycobacterial species with Crohn's disease.

Polymorphisms in tumour necrosis factor and adhesion molecule genes in patients with inflammatory bowel disease: associations with HLA-DR and -DQ alleles and subclinical markers

BACKGROUND

When investigating susceptibility to inflammatory bowel disease (IBD), a multifactorial disorder with a genetic predisposition, polymorphisms of molecules with immunoregulatory function are of potential interest. This is the first time that the polymorphisms of HLA-DR and -DQ, tumour necrosis factor (TNF), E-selectin (CD62E), L-selectin (CD62L), and intercellular adhesion molecule 1 (ICAM-1, CD54) were determined in Estonians, a population with a low IBD incidence rate, and their occurrence investigated in subgroups of a total of 53 IBD patients.

METHODS

The reverse hybridization principle and sequence specific primers were used for HLA genotyping. To analyse the TNF and adhesion molecule polymorphisms, the polymerase chain reaction with subsequent restriction fragment length polymorphism or single-strand conformation polymorphism method was used.

RESULTS

In the subgroup of antineutrophil cytoplasmic antibody (ANCA)-positive ulcerative colitis (UC) patients we found a higher frequency of the TNF2 (20.8% versus 0.0% in ANCA-negative UC patients, P = 0.051) and HLA-DRB1*15 allele (35.4% versus 15.7% in controls; P = 0.004). Of ANCA-positive UC patients 87.5% were carriers of one of these alleles (22.2% among ANCA-negative UC patients (P<0.001, Pc = 0.039) and 51.4% among controls (P = 0.002). Specific typing of HLA-DRB1*15 alleles showed that the HLA-DRB1*1501 allele was responsible for the HLA-DRB1*15 association with ANCA-positive UC. Associations of ICAM-1, E-selectin, or L-selectin polymorphisms with IBD were not found.

CONCLUSIONS

TNF2 and HLA-DRB1*15 alleles were associated with ANCA-positive UC in the investigated population. ANCA might be a useful marker, at least in some ethnic groups, for dividing IBD patients into genetically more homogeneous subgroups.

Are anti-neutrophil cytoplasmic antibodies (ANCA) clinically useful in inflammatory bowel disease (IBD)?

Since the first detection of ANCA in IBD, numerous studies have dealt with their prevalence, antigenic specificities, clinical significance, pathophysiological role, and their induction. This review summarizes the information obtained from those studies and shows that ANCA are not directly useful as diagnostic and prognostic factors in IBD. ANCA were detected in 50-85% of patients with ulcerative colitis (UC) and 10-20% of patients with Crohn's disease (CD). Multiple target antigens are recognized by these autoantibodies, including both cytoplasmic and nuclear proteins. A pathophysiological role for ANCA in IBD is far from clear. On the one hand, it is suggested that ANCA are genetic markers of susceptibility for IBD, and on the other hand, the induction of ANCA in those diseases may just be an epiphenomenon of chronic inflammation. We discuss recent evidence that ANCA may be induced by a break-through of tolerance towards bacterial antigens.