Ulcerative colitis: a genetically heterogeneous disorder defined by genetic (HLA class II) and subclinical (antineutrophil cytoplasmic antibodies) markers

Optimizing 5-aminosalicylate for moderate ulcerative colitis: expert recommendations from the Asia-Pacific, Middle East, and Africa Inflammatory Bowel Disease Coalition

The lack of clear definition and classification for "moderate ulcerative colitis (UC)" creates ambiguity regarding the suitability of step-up versus top-down treatment approaches. In this paper, experts address crucial gaps in assessing and managing moderate UC. The Asia-Pacific, Middle East, and Africa Inflammatory Bowel Disease Coalition comprised 24 experts who convened to share, discuss and vote electronically on management recommendations for moderate UC. Experts emphasized that the goal of treating UC is to attain clinical, biomarker, and endoscopic remission using cost-effective strategies such as 5-aminosalicylates (5-ASAs), well-tolerated therapy that can be optimized to improve outcomes. Experts agreed that 5-ASA therapy could be optimized by maximizing dosage (4 g/day for induction of remission), combining oral and topical administration, extending treatment duration beyond 8 weeks, and enhancing patient adherence through personalized counselling and reduced pill burden. Treatment escalation should ideally be reserved for patients with predictors of aggressive disease or those who do not respond to 5-ASA optimization. Premature treatment escalation to advanced therapies (including biologics and oral small molecules) may have long-term health and financial consequences. This paper provides consensus-based expert recommendations and a treatment algorithm, based on current evidence and practices, to assist decision-making in real-world settings.

Mucosal lesions of the upper gastrointestinal tract in patients with ulcerative colitis: A review

Ulcerative colitis (UC) is a chronic, nonspecific, relapsing inflammatory bowel disease. The colorectum is considered the chief target organ of UC, whereas upper gastrointestinal (UGI) tract manifestations are infrequent. Recently, emerging evidence has suggested that UC presents complications in esophageal, stomachic, and duodenal mucosal injuries. However, UC-related UGI tract manifestations are varied and frequently silenced or concealed. Moreover, the endoscopic and microscopic characteristics of UGI tract complicated with UC are nonspecific. Therefore, UGI involvement may be ignored by many clinicians. In addition, no standard criteria have been established for patients with UC who should undergo fibrogastroduodenoscopy. Furthermore, specific treatment recommendations may be needed for patients with UC-associated UGI lesions. Herein, we review the esophageal, gastric, and duodenal mucosal lesions of the UC-associated UGI tract, as well as the potential pathogenesis and therapy.

Expression of IL-1 and IL-10 mRNAs in colonic tissue of ulcerative colitis rats with abnormal sapra syndrome

AIM

To investigate the role of interleukin (IL)-1α, IL-1β and IL-10 in the pathogenesis and development of ulcerative colitis in rats with abnormal sapra syndrome.

METHODS

A rat model of abnormal sapra syndrome was used to develop UC using trinitro-benzene-sulfonic acid (TNBS)/ethanol. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to detect the differences in IL-1α, IL-1β and IL-10 mRNA expression levels in the colonic tissues between normal rats (control group) and UC rats with abnormal sapra syndrome (model group).

RESULTS

Rat signs, symptoms and colonic mucosa damage suggested that UC with abnormal sapra syndrome was successfully induced. qRT-PCR results showed that compared with the normal group, the expression of IL-1α, IL-1β and IL-10 mRNAs was significantly up-regulated in the model group (P < 0.05).

CONCLUSION

Imbalance of inflammatory factors may occur in colon tissue of UC rats with abnormal sapra syndrome.

Microbiome, Metabolome and Inflammatory Bowel Disease

Inflammatory Bowel Disease (IBD) is a multifactorial disorder that conceptually occurs as a result of altered immune responses to commensal and/or pathogenic gut microbes in individuals most susceptible to the disease. During Crohn’s Disease (CD) or Ulcerative Colitis (UC), two components of the human IBD, distinct stages define the disease onset, severity, progression and remission. Epigenetic, environmental (microbiome, metabolome) and nutritional factors are important in IBD pathogenesis. While the dysbiotic microbiota has been proposed to play a role in disease pathogenesis, the data on IBD and diet are still less convincing. Nonetheless, studies are ongoing to examine the effect of pre/probiotics and/or FODMAP reduced diets on both the gut microbiome and its metabolome in an effort to define the healthy diet in patients with IBD. Knowledge of a unique metabolomic fingerprint in IBD could be useful for diagnosis, treatment and detection of disease pathogenesis.

TNFRSF1B Is Associated with ANCA in IBD

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

NOD2 gene mutations in ulcerative colitis: useless or misunderstood?

PURPOSE

NOD2 mutations have been linked to an increased risk of Crohn's disease and to some of its phenotypes. The association between NOD2 mutations and susceptibility to ulcerative colitis (UC) remains somewhat controversial and potential correlations between these mutations and UC phenotype have not been studied.

AIM

To assess whether NOD2 mutations are a risk factor for UC in Portugal and if there are any genotype-phenotype correlations in these patients.

METHODS

The three main NOD2 mutations were searched in 200 patients with UC and in 202 healthy controls.

RESULTS

NOD2 mutations were present in 28 patients with UC (14.0 %) and in 27 controls (13.4 %) (p = 0.853). Mutation carriers were more likely to receive steroids during the first year of disease than non-carriers (54.2 % vs. 29.6 %, p = 0.018) and among these patients the need for intravenous administration was more frequent in those with the R702W polymorphism (90.0 % vs. 45.5 %, p = 0.014). In patients with severe colitis admitted for intravenous steroids, a greater proportion of mutation carriers was considered intravenous-steroid refractory and required salvage therapy (90.0 % vs. 38.1 %, p = 0.004). Patients with NOD2 mutation were submitted to colectomy more frequently than non-carriers (17.9 % vs. 4.1 %. p = 0.015). No correlation with the need for immunosuppressants/immunomodulators was found.

CONCLUSIONS

In the Portuguese population, NOD2 mutations do not increase the risk of UC but are associated with a more aggressive course including greater need of steroids in the first year, increased incidence of intravenous-steroid refractoriness and a higher colectomy rate.

Genetic predictors of medically refractory ulcerative colitis

BACKGROUND

Acute severe ulcerative colitis (UC) remains a significant clinical challenge and the ability to predict, at an early stage, those individuals at risk of colectomy for medically refractory UC (MR-UC) would be a major clinical advance. The aim of this study was to use a genome-wide association study (GWAS) in a well-characterized cohort of UC patients to identify genetic variation that contributes to MR-UC.

METHODS

A GWAS comparing 324 MR-UC patients with 537 non-MR-UC patients was analyzed using logistic regression and Cox proportional hazards methods. In addition, the MR-UC patients were compared with 2601 healthy controls.

RESULTS

MR-UC was associated with more extensive disease (P = 2.7 × 10(-6)) and a positive family history of UC (P = 0.004). A risk score based on the combination of 46 single nucleotide polymorphisms (SNPs) associated with MR-UC explained 48% of the variance for colectomy risk in our cohort. Risk scores divided into quarters showed the risk of colectomy to be 0%, 17%, 74%, and 100% in the four groups. Comparison of the MR-UC subjects with healthy controls confirmed the contribution of the major histocompatibility complex to severe UC (peak association: rs17207986, P = 1.4 × 10(-16)) and provided genome-wide suggestive association at the TNFSF15 (TL1A) locus (peak association: rs11554257, P = 1.4 × 10(-6)).

CONCLUSIONS

A SNP-based risk scoring system, identified here by GWAS analyses, may provide a useful adjunct to clinical parameters for predicting the natural history of UC. Furthermore, discovery of genetic processes underlying disease severity may help to identify pathways for novel therapeutic intervention in severe UC.

The prevalence and clinical significance of perinuclear anti-neutrophil cytoplasmic antibody in Korean patients with ulcerative colitis

Perinuclear anti-neutrophil cytoplasmic antibody (pANCA) is a serological marker associated with various immune-mediated diseases whose clinical significance and possible diagnostic roles in ulcerative colitis (UC) are still unclear. We aimed to evaluate the prevalence of pANCA expression and its association with clinical findings and disease course in Korean patients with UC. This study included 484 patients with UC who were diagnosed and treated between 1990 and 2006 at Severance Hospital, Yonsei University, Seoul, Korea, and were followed for at least 1 year. Clinical findings at diagnosis, disease extent, treatment modalities used, and cumulative relapse rates were analyzed and compared to pANCA expression. Of the 484 patients, 405 (83.7%) were evaluated for pANCA and were eligible for analysis. The overall pANCA prevalence was 22.1%, with a female preponderance (male, 21.5%; female, 31.6%; P < 0.05). Proctitis was more common in pANCA-negative patients (pANCA-negative, 37.6%; pANCA-positive, 25.2%, P < 0.05). UC activity index and cumulative relapse rates were higher in pANCA-positive patients. However, there were no significant differences in the cumulative probability of steroid and immunosuppressant use and operation rate between the two groups. The prevalence of pANCA expression in Korean patients with UC was relatively low compared to that in Western countries. Although UC patients with pANCA expression had more severe clinical findings at diagnosis and higher cumulative relapse rates in our study, further prospective studies are warranted to clarify whether pANCA positivity influences the initial clinical presentation or disease aggressiveness.

Inflammatory bowel disease: review from the aspect of genetics

Regardless of how inflammatory bowel disease (IBD) is defined, the term "genetic susceptibility" is always included. Due to substantial progress in the characterization of susceptible genes that interact with environmental influences, a number of review articles offering the latest insights continue to be presented. To date, more than 30 novel IBD susceptible loci have been found, while several promising associations between IBD and gene variants have also been identified and replicated effectively. The present review highlights recent insights regarding linkage analysis and genome-wide association presented in studies of IBD susceptible genes, which provide additional evidence supporting their involvement in disease pathogenesis, based on linking to innate immune systems as a result of interactions with intestinal microbial flora. An improved understanding of IBD genetics will promote the identification of novel therapeutic agents, making it possible to identify environmental factors related to intestinal inflammation.

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.

Inflammatory bowel disease: Genetic and epidemiologic considerations

Genome-wide association studies have firmly established that many genomic loci contribute to inflammatory bowel disease, especially in Crohn’s disease. These studies have newly-established the importance of the interleukin 23 and autophagy pathways in disease pathogenesis. Future challenges include: (1) the establishment of precisely causal alleles, (2) definition of altered functional outcomes of associated and causal alleles and (3) integration of genetic findings with environmental factors.

Once-daily MMX mesalamine for the treatment of mild-to-moderate ulcerative colitis

First-line therapies in the treatment of patients with mild-to-moderate ulcerative colitis are sulfasalazine or one of the mesalamine derivatives. Mesalamine is popular given its safety profile and reasonable efficacy in many patients. However, compliance is poor with regimens demanding large number of pills dosed multiple times a day and non-compliance has been correlated with disease relapse. Mesalamine requires direct contact with the inflamed colonic mucosa. To avoid proximal absorption, a variety of delivery systems has been utilized to time the release of active mesalamine to the areas affected by colitis. The most common mesalamine release mechanisms include azo-bond prodrug carriers, pH-dependent dissolution, and moisture-sensitive product dispersion. Novel technology has resulted in the development and FDA-approval of a multi-matrix release (MMX) mesalamine. Pharmacodynamic studies suggest a reliable drug delivery system with homogenous release throughout the entire colon. By incorporating the largest amount of mesalamine (1.2 g) per pill, this new product dramatically decreases the number of pills needed to attain a therapeutic daily dosage, and is the first agent approved at once-daily dosing. These factors are expected to increase patient compliance with prescribed mesalamine dosing, and in turn decrease relapse rates of active ulcerative colitis.

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

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

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.

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.

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Left-sided ulcerative colitis

Left-sided ulcerative colitis is not a distinct entity, but a less extensive form of pancolitis. The epidemiologic and genetic characteristics are thought to be analogous. The rate of colorectal cancer, however, seems to be proportional to the extent of disease. Primary treatment for left-sided disease is topical 5-aminosalicyclic acid (5ASA) agents. In patients who do not respond to topical therapy, oral 5ASA agents of differing delivery methods to the distal bowel can be used. There is much debate pertaining to the clinical superiority of the oral 5ASA agents.

Bacterial flagellin is a dominant antigen in Crohn disease

Chronic intestinal inflammation, as seen in inflammatory bowel disease (IBD), results from an aberrant and poorly understood mucosal immune response to the microbiota of the gastrointestinal tract in genetically susceptible individuals. Here we used serological expression cloning to identify commensal bacterial proteins that could contribute to the pathogenesis of IBD. The dominant antigens identified were flagellins, molecules known to activate innate immunity via Toll-like receptor 5 (TLR5), and critical targets of the acquired immune system in host defense. Multiple strains of colitic mice had elevated serum anti-flagellin IgG2a responses and Th1 T cell responses to flagellin. In addition, flagellin-specific CD4(+) T cells induced severe colitis when adoptively transferred into naive SCID mice. Serum IgG to these flagellins, but not to the dissimilar Salmonella muenchen flagellin, was elevated in patients with Crohn disease, but not in patients with ulcerative colitis or in controls. These results identify flagellins as a class of immunodominant antigens that stimulate pathogenic intestinal immune reactions in genetically diverse hosts and suggest new avenues for the diagnosis and antigen-directed therapy of patients with 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.

A population- and family-based study of Canadian families reveals association of HLA DRB1*0103 with colonic involvement in inflammatory bowel disease

The aim of this study was to identify major histocompatibility complex alleles associated with the development and clinical features of inflammatory bowel disease (IBD). Genotyping at the human leukocyte antigen (HLA) DRB1 and DQB1 loci was performed on individuals from 118 Caucasian IBD sibling pair families and on 216 healthy controls. Both population- and family-based association tests were used to analyze data obtained on the entire study population and on clinical subgroups stratified by diagnosis, ethnicity, and disease distribution. HLA DRB1*0103 was significantly associated with IBD (OR = 6.0, p = 0.0001) in a case-control analysis of non-Jewish IBD-affected individuals. This association was apparent among both Crohn's disease (OR = 5.23, p = 0.0007) and ulcerative colitis (OR = 7.9, p = 0.0001) patients and was confirmed in the non-Jewish IBD population by results of family-based association analysis using the transmission disequilibrium test. HLA DQB1*0501 was also associated with IBD (OR = 1.64, p = 0.02) in the non-Jewish population. but statistically significant association of this allele with disease was not detected for Crohn's disease and ulcerative colitis separately. No significant associations were identified among the Jewish patients. In the non-Jewish IBD families, IBD was as strongly associated with the DRB1*0103 DQB1*0501 haplotype as with the DRB1*0103 allele alone. The carrier frequency of the DRB1*0103 allele was found to be 10-fold higher in Crohn's disease patients with pure colonic involvement than in healthy controls (38.5% vs. 3.2%; p = 0.0002). These data demonstrate the association of the HLA DRB1*0103 allele with both Crohn's disease and ulcerative colitis and with large intestine-restricted disease in non-Jewish IBD patients and therefore identify HLA DRB1*0103 as a potentially important contributor to disease susceptibility and to expression of colonic involvement in IBD.

Association between K469E allele of intercellular adhesion molecule 1 gene and inflammatory bowel disease in a Japanese population

BACKGROUND AND AIMS

The genetic contribution to inflammatory bowel disease (IBD) is under investigation. Recent evidence indicates a significant linkage between a locus on chromosome 19p13 and IBD. We investigated the association between an intercellular adhesion molecule 1 gene (ICAM-1) polymorphism located on chromosome 19p13 and IBD in a Japanese population.

METHODS

We compared 207 Japanese patients who had IBD (79 with Crohn's disease (CD); 128 with ulcerative colitis (UC)) with 103 unrelated Japanese controls. We determined R241G and K469E polymorphisms of the ICAM-1 gene using polymerase chain reaction (PCR) techniques.

RESULTS

Both frequency and carriage rate of the K469 allele were significantly higher in IBD patients than in controls (allelic frequency, p(c)=0.0026; carriage rate, p(c)=0.0034; odds ratio 2.59; 95% confidence interval 1.42-4.68). Furthermore, the frequency of the K469 allele was significantly increased in both CD and UC. Subgroup analysis demonstrated that both K469 allelic frequency and K469 carriage rate were significantly higher in patients with the small bowel and colon type of CD and entire colitis compared with healthy controls.

CONCLUSIONS

We identified an overall association between IBD and ICAM-1 K469 in a Japanese population. Further studies of this chromosome region are required to elucidate the gene responsible for IBD.

Polymorphisms of the ICAM-1 gene are associated with inflammatory bowel disease, regardless of the p-ANCA status

The intercellular adhesion molecule-1 (ICAM-1) is of paramount importance for the initiation and propagation of various inflammatory conditions. An increased frequency of allele R241 of the ICAM-1 gene was previously described in p-ANCA-negative as compared to p-ANCA-positive ulcerative colitis and vice versa in Crohn's disease. One hundred sixteen healthy unrelated controls, 121 patients with ulcerative colitis, and 96 patients with Crohn's disease were genotyped for two polymorphisms of the ICAM-1 gene (R/G241, exon 4; and K/E469, exon 6), employing dot-blot hybridization and stratified according to their p-ANCA status. When compared with the control group the frequency of the allele R241 (P = 0.024) and the heterozygous genotype R/G241, P = 0.032) were significantly increased in ulcerative colitis, whereas the homozygous genotype G/G241 was found less frequently (P = 0.022). The heterozygous genotype K/E469 was observed less frequently (P = 0.001 and 0.037, resp.) than the homozygous genotype E/E469, which was more frequent in Crohn's disease and ulcerative colitis (P = 0.002 and 0.012, respectively). Further significant differences concerning the allele or genotype distribution were not observed. After stratification for the p-ANCA status significant differences concerning the frequencies of both the R241 and the E469 alleles were not detected when p-ANCA-positive inflammatory bowel disease and p-ANCA-negative inflammatory bowel disease were compared. Ulcerative colitis and Crohn's disease are associated with polymorphisms of the ICAM-1 gene, which might therefore represent a functional candidate gene. However, the observed associations are independent of the p-ANCA status.

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.

Stratification analysis of MICA triplet repeat polymorphisms and HLA antigens associated with ulcerative colitis in Japanese

We previously reported a conserved haplotype of HLA B52-DR2 and a significantly high frequency of the major histocompatibility complex (MHC) class I chain-related gene A (MICA) transmembrane-short tandem repeat (TM-STR) 6 allele in Japanese patients with ulcerative colitis (UC). To examine the predominance of the MICA TM-STR 6 allele as a marker of the susceptibility to UC within the susceptible haplotype, the association of each allele with UC was estimated following stratification of the patients to control for any possible confounding effects of other alleles positively associated with UC. Sixty-four patients with UC and 236 unrelated healthy controls were included in this study. All subjects were Japanese. HLA-A, -B, -C, and -DR antigens were determined serologically. A triplet repeat polymorphism of the MICA was determined by direct sequencing. To control for the effect of linkage disequilibrium, Mantel-Haenszel weighed odds ratios were calculated. Significantly higher phenotype frequencies of B52, MICA TM-STR 6, and DR2 were observed in patients with UC. Linkage disequilibria among alleles associated with UC revealed that a B52 - MICA TM-STR 6 - DR2 haplotype was conserved in patients with UC, as in controls. When the association of HLA-B52 was estimated after patient stratification for the possible confounding effect of MICA TM-STR 6 or DR2, a strong significant association of B52 with UC was still observed. In contrast, no association with UC was observed for MICA TM-STR 6 or DR2, after stratification of the possible confounding effect of HLA-B52. These results imply that the significant increase in MICA TM-STR 6 in Japanese patients with UC is attributable to linkage disequilibrium with HLA-B52.

Delta 32 mutation of the chemokine-receptor 5 gene in inflammatory bowel disease

The gene encoding chemokine receptor 5 (CCR5) is colocalized to the microsatellite marker D3S1573, which was linked with inflammatory bowel disease. Genetic heterogeneity in inflammatory bowel disease might be defined by a combination of the p-ANCA status and immunoregulatory genes. One hundred and twenty healthy unrelated controls, 101 patients with Crohn's disease, and 99 patients with ulcerative colitis were genotyped for the Delta 32 mutation of the CCR5 gene. The presence of p-ANCA was determined by the use of indirect immunofluorescence. After genotyping, patients were stratified according to p-ANCA status. The frequency of the Delta 32 mutation was not significantly different in controls and patients with Crohn's disease or ulcerative colitis (P 0.207 or more). Moreover, the frequency of the mutation was not significantly different in patients with inflammatory bowel disease after stratification for the p-ANCA status (P 0.482). Regardless of the p-ANCA status, Crohn's disease and ulcerative colitis are not associated with the Delta 32 mutation of the CCR5 gene.

Marker antibody expression stratifies Crohn's disease into immunologically homogeneous subgroups with distinct clinical characteristics

BACKGROUND

Perinuclear antineutrophil cytoplasmic antibodies (pANCA) have been detected in a clinically distinct Crohn's disease subpopulation. Antibodies to Saccharomyces cerevisiae (ASCA) have been demonstrated in the majority of patients with Crohn's disease.

AIMS

To examine the relationship between selective marker antibody expression in Crohn's disease and disease onset, location, and clinical behaviour patterns.

METHODS

Sera from 156 consecutive patients with established Crohn's disease were evaluated in a blinded fashion for the presence of ASCA and ANCA. Clinical profiles were generated by investigators blinded to immune marker status.

RESULTS

Using multiple regression analyses, higher ASCA levels were shown to be independently associated with early age of disease onset as well as both fibrostenosing and internal penetrating disease behaviours. Higher ANCA levels were associated with later age of onset and ulcerative colitis-like behaviour. Substratification of the Crohn's disease population using selective ANCA and ASCA expression (high levels of a single marker antibody): (1) distinguished homogeneous subgroups that manifested similar disease location and behaviours; and (2) identified patients with more aggressive small bowel disease.

CONCLUSIONS

The findings suggest that by taking into account the magnitude of the host immune response, Crohn's disease can now be stratified on an immunological basis into more homogeneous clinically distinct subgroups, characterised by greater uniformity among anatomical distribution of disease and disease behaviour.

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.

HLA class II alleles associated with susceptibility and resistance to Crohn's disease in the Jewish population

Previous studies have suggested that susceptibility to Crohn's disease (CD) is associated with the histocompatibility complex (HLA) class II alleles DR1, DQ5, and DR13 in the Caucasian population, DR7 in the French and German populations, and DR4 and DQ4 in the Japanese population. However, little is known about the relationship between HLA class II alleles and CD in the Jewish population since these previous studies included few Jewish individuals. In order to determine whether the HLA associations observed with predominantly non-Jewish populations were also present in the Jewish CD population and whether there were any HLA class II alleles uniquely associated with CD in the Jewish population, 132 CD patients, of which 82 were Ashkenazi Jewish, were HLA-typed using serologic and DNA methods. Ethnically matched controls were similarly typed. No association with DR1 or DR13 was observed in the Jewish CD population although an association with DR13 (OR [odds ratio] = 5.3, p = 0.02) was observed in the non-Jewish CD population. However, an association with DR15 (OR = 2.7, p = 0.03), which is normally associated with ulcerative colitis, was observed in the Jewish, but not non-Jewish, CD group. In addition, a strong negative association was observed with DR3, which was especially striking in the Jewish population (OR = 0.35, p = 0.025); similar negative associations with DR3 have been observed by others using non-Jewish populations. Furthermore, a significant negative association with DR7 (OR = 0.45, p = 0.04) was observed in the Jewish, but not non-Jewish, population. Consistent with this was the negative association with DQ2 (OR = 0.38, p = 0.005), which is in strong linkage disequilibrium with both DR3 and DR7, in the Jewish, but not non-Jewish, population. These studies support previous suggestions that susceptibility to CD in Jewish and non-Jewish populations is determined by distinct genes and provide further support to the hypothesis that a gene on the DR3 haplotype may protect against CD. Furthermore, protection is conferred by the same or another gene found on Jewish, but not non-Jewish, DR7 haplotypes.

HLA class II haplotype associations with inflammatory bowel disease in Jewish (Ashkenazi) and non-Jewish caucasian populations

Ulcerative colitis (UC) and Crohn's disease (CD) are the clinical entities comprising idiopathic inflammatory bowel disease (IBD). Previous studies on the association of IBD and human leukocyte antigen (HLA) class II genes suggested a role for HLA in this disease. Here we present HLA class II (DRB1, DQB1, DQA1, DPB1) allele and haplotype distributions determined using the polymerase chain reaction and sequence-specific oligonucleotide probe methods. A total of 578 UC and CD Caucasian patients and controls from Jewish (Ashkenazi) and non-Jewish populations was examined. Our previously reported association of DR1-DQ5 with CD was attributable to DRB1*0103. A dramatic association with IBD and the highly unusual DRB1*0103-DQA1*0501-DQB1*0301 haplotype (OR = 6.6, p = 0.036) was found. The more common DR1 haplotype, DRB1*0103-DQA1*0101-DQB1*0501, was also associated with IBD (OR = 3.1, p = 0.014), a result suggesting that interaction between DR and DQ may determine the extent of disease risk. Our previously reported association of DR2 with UC was attributable to DRB1*1502 (OR = 2.6, p = 0.006). At the DPB1 locus, a significant association of DPB1*0401 with CD was observed for the combined populations (OR = 1.85, p = 0.007). These observations indicate that some class II alleles and haplotypes confer susceptibility to both UC and CD, implying common immunogenetic mechanisms of pathogenesis, while others confer risk to only one of these diseases, and illustrate the value of DNA HLA typing in disease susceptibility analyses.

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.

Identification of histone H1 as a cognate antigen of the ulcerative colitis-associated marker antibody pANCA

Perinuclear anti-neutrophil cytoplasmic antibody (pANCA)(4)is a predominant serum marker of ulcerative colitis (UC), and a familial trait associated with disease susceptibility and disease associated MHC haplotypes. This study characterizes the pANCA antigen defined by representative UC-pANCA human monoclonal antibodies, Fab 5-3 and 5-2. Western blot analysis probed with Fab 5-3 revealed specific binding to a nuclear protein doublet (apparent MW=32-33 kDa) expressed in several cell types. Purification and tryptic peptide sequencing identified the protein as histone H1, and this specificity was confirmed by Fab 5-3 binding to purified H1. Rabbit anti-histone H1 immunostaining and Western blot analysis confirmed that the pANCA epitope is preferentially immunoaccessible in polymorphonuclear neutrophils (PMN). The epitope was localized to the COOH-terminal region by site-specific proteolysis, and recombinant deletants further localized binding activity for both Fab 5-2 and 5-3 to two non-overlapping segments (AA 69-171 and 172-226) associated with a recurring PKKAK motif. Serum IgG binding was detectable to these segments, but was not significantly correlated with pANCA titer or disease status. These findings indicate that histone H1 bears a recurring COOH-terminal epitope recognized by monoclonal ulcerative colitis-associated pANCA marker antibodies, but this epitope is not a predominant specificity of serum pANCA.

Familial expression of anti-Saccharomyces cerevisiae mannan antibodies in affected and unaffected relatives of patients with Crohn's disease

BACKGROUND

Crohn's disease is a familial disorder, and antiglycan antibodies to the cell wall mannan of Saccharomyces cerevisiae (ASCA) are highly correlated with Crohn's disease.

AIMS

To determine whether there is a familial pattern for expression of serum levels of anti-mannan Ig, and whether this trait is expressed in clinically unaffected Crohn's disease family members.

METHODS

349 patients with Crohn's disease, 87 Crohn's disease affected relatives, 333 inflammatory bowel disease (IBD) free relatives, 58 spouses, and 190 healthy control patients were studied. Serum IgG and IgA binding activity to S cerevisiae cell wall mannan was quantitated by ELISA.

RESULTS

A high percentage of patients with Crohn's disease (51.9%) and affected family members (56.3%) were seropositive for anti-mannan Ig, compared with the normal control population (3.7%). Seropositive and seronegative phenotypes of Crohn's disease probands were correlated among all affected relatives, and this association was stronger in affected first degree relatives. Statistical intraclass correlations of quantitative anti-mannan Ig levels revealed significantly less variation within, rather than between families. A significant familial aggregation was observed for affected relatives; this was even stronger for unaffected relatives. While a significant familial aggregation was observed among unaffected siblings pairs, there was no significant correlation among marital pairs.

CONCLUSION

Results show that anti-mannan Ig in family members affected and unaffected with Crohn's disease is a familial trait for both affected and unaffected relatives. The lack of concordance in marital pairs indicates that familiality is due in part to a genetic factor or childhood environmental exposure.

Mast cell and neuroendocrine cytoplasmic autoantigen(s) detected by monoclonal pANCA antibodies

pANCA is a marker antibody expressed in most patients with ulcerative colitis, and its cognate antigen is potentially an immunologic target in this disease. This study evaluates whether pANCA detects an autoantigen that is expressed in the colonic mucosa. Immunohistochemistry of colon specimens with human pANCA monoclonal antibodies (Fab 5-2 and 5-3) revealed a minor population of immunoreactive mucosal cells bearing a cytoplasmic vesicle antigen. By distribution, morphology, and tryptase expression, these were identified as mast cells. Immunofluorescent analysis revealed similar immunoreactivity of mouse mast cell lines and human KU812. Western analysis of mouse mast cell lines revealed immunoreactive proteins, and these were distinct from previously proposed pANCA antigens (histone H1, HMG 1 and 2, and neutrophil vesicle antigens). Cognate antigen for Fab 5-2 and 5-3 was also expressed in other tissue mast cells, cerebellar neurons, and pancreatic islet cells. These findings identify a novel cytoplasmic autoantigen(s) associated with UC by its presence in colonic mucosa and recognition by a disease-associated marker antibody.

Serologic testing in inflammatory bowel disease: its value in indeterminate colitis

Serologic testing in inflammatory bowel disease provides a unique tool to classify these diseases into more homogeneous groups. Serum markers can also be used to identify common antigenic triggers and specific defects in mucosal immune regulation and cytokine imbalance in different parts of the gastrointestinal tract. ANCA (antineutrophil cytoplasmic antibodies) and ASCA (anti-Saccharomyces cerevisiae antibodies), the most extensively studied serologic markers, have been used to classify ulcerative colitis and Crohn's disease into such groups with certain phenotypic characteristics and responses to treatment. Similar studies have been initiated in indeterminate colitis, and these results will help in the future to define the immunopathogenesis, prognosis, and response to certain treatments in patients with this type of disease.

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.

Functional and ethnic association of allele 2 of the interleukin-1 receptor antagonist gene in ulcerative colitis

BACKGROUND & AIMS

The role of the interleukin (IL)-1 receptor antagonist (IL-1ra) in predisposing an individual to inflammatory bowel disease (IBD) is controversial. This study aimed to determine the association between intron 2 IL-1ra polymorphism and IBD by performing a multiethnic case-control study and to assess its functional significance.

METHODS

A total of 236 patients with ulcerative colitis (UC), 196 patients with Crohn's disease (CD), and 338 ethnically matched control patients treated at LAC-USC and Cedars-Sinai Medical Centers and the University of Milan Medical Center were genotyped for a variable length polymorphism in intron 2 of the IL-1ra gene (IL-1RN). Total IL-1ra protein production rates in peripheral blood mononuclear cells (PBMCs) were correlated with carriage of allele 2 of the IL-1RN gene (IL-1RN*2).

RESULTS

In the LAC-USC group, UC patients (n = 60) had an increased frequency of at least 1 copy of IL-1RN*2 compared with controls (n = 129) (70% vs. 33%; P < 0.01; odds ratio [OR], 4.7). The frequency of IL-1RN*2 carriage in the Cedars-Sinai group was 59% in UC, 45% in CD, and 42% in controls (P < 0.01; OR, 2.0). A significant difference was observed only in the Jewish subgroup (P = 0.003; OR, 5.0). The association was not detected in UC or CD patients treated at the University of Milan. The ORs of 4.7 and 5.0 appear to be the highest reported in any UC population for any genetic markers. Further, carriage of IL-1RN*2 was associated with decreased production of total IL-1ra protein in cultured PBMCs from both UC patients and controls.

CONCLUSIONS

These results provide further evidence that IL-1ra is important in the predisposition to UC, there may be genetic or pathogenetic heterogeneity between different ethnic groups, and UC and CD are genetically distinct diseases.

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.

Autoimmune cholangiopathy

Currently available evidence is insufficient to classify PBC and AIC as separate diseases. The ultimate answer to the question of whether AIC, defined as AMA-negative PBC with ANA or SMA, is a disease distinct from AMA-positive PBC with or without ANA will require a detailed comparison of etiologic factors and pathogenetic mechanisms, once they are elucidated. It is intriguing to consider the suggestion of Heathcote that the term autoimmune cholangitis be adopted to describe PBC with or without detectable AMA. However, it is improbable that the venerable term PBC will be supplanted. Hepatologists will probably continue to use the terms AIC and AMA-negative PBC interchangeably, with little risk of being misunderstood.

Current theories on the causes of inflammatory bowel disease

The understanding of the pathogenesis of CD and UC has greatly expanded over the last decade. The combination of abnormalities in the immune system, the contribution of nonimmune cells in the intestinal mucosa, a variety of genetic risk determinants, and random environmental factors may all be necessary to induce what clinically presents as IBD. It is likely that several agents can initiate an immune response that in the intestinal microenvironment and the genetic background of the patient finally leads to pathology.

Circulating myeloperoxidase and anti-myeloperoxidase antibody in patients with vasculitis

To evaluate a role of myeloperoxidase (MPO) and antibody to myeloperoxidase (anti-MPO) in vasculitis, MPO and anti-MPO were determined by enzyme-linked immunosorbent assays in sera from 43 patients with vasculitis, 40 with rheumatoid arthritis, 36 with systemic lupus erythematosus (SLE), 23 with mixed connective tissue disease, 13 with systemic sclerosis, 22 with polymyositis/dermatomyositis, 18 with Sjögren's syndrome, and 30 normal controls. Kidney and lung sections from patients with vasculitis were stained for MPO. Anti-MPO titers were significantly higher (p<0.005) in the patients with vasculitis (mean+/- SD absorbance at 405 nm: 0.53 +/- 0.37) than in any other groups (0.15 +/- 0.04 to approximately 0.21 +/- 0.11). MPO levels in patients with vasculitis were comparable with those in patients with other diseases except SLE. In two patients with vasculitis, anti-MPO decreased sharply with simultaneous increases in MPO 1-2 weeks after they developed pulmonary hemorrhage. Numerous cells positive for MPO infiltrated the Bowman's spaces. These results indicate that MPO may contribute to the pathogenesis of vasculitis and a sudden fall in anti-MPO may predict a poor prognosis in some cases.

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.