The contribution of human leucocyte antigen complex genes to disease phenotype in ulcerative colitis

Inflammatory auto-immune diseases of the intestine and their management by natural bioactive compounds

Autoimmune diseases are caused by the overactivity of the immune system towards self-constituents. Risk factors of autoimmune diseases are multiple and include genetic, epigenetic, environmental, and psychological. Autoimmune chronic inflammatory bowel diseases, including celiac and inflammatory diseases (Crohn's disease and ulcerative colitis), constitute a significant health problem worldwide. Besides the complexity of the symptoms of these diseases, their treatments have only been palliative. Numerous investigations showed that natural phytochemicals could be promising strategies to fight against these autoimmune diseases. In this respect, plant-derived natural compounds such as flavonoids, phenolic acids, and terpenoids exhibited significant effects against three autoimmune diseases affecting the intestine, particularly bowel diseases. This review focuses on the role of natural compounds obtained from medicinal plants in modulating inflammatory auto-immune diseases of the intestine. It covers the most recent literature related to the effect of these natural compounds in the treatment and prevention of auto-immune diseases of the intestine.

Identification of a Disease-Associated Network of Intestinal Immune Cells in Treatment-Naive Inflammatory Bowel Disease

Chronic intestinal inflammation underlies inflammatory bowel disease (IBD). Previous studies indicated alterations in the cellular immune system; however, it has been challenging to interrogate the role of all immune cell subsets simultaneously. Therefore, we aimed to identify immune cell types associated with inflammation in IBD using high-dimensional mass cytometry. We analyzed 188 intestinal biopsies and paired blood samples of newly-diagnosed, treatment-naive patients (n=42) and controls (n=26) in two independent cohorts. We applied mass cytometry (36-antibody panel) to resolve single cells and analyzed the data with unbiased Hierarchical-SNE. In addition, imaging-mass cytometry (IMC) was performed to reveal the spatial distribution of the immune subsets in the tissue. We identified 44 distinct immune subsets. Correlation network analysis identified a network of inflammation-associated subsets, including HLA-DR⁺CD38⁺ EM CD4⁺ T cells, T regulatory-like cells, PD1⁺ EM CD8⁺ T cells, neutrophils, CD27⁺ TCRγδ cells and NK cells. All disease-associated subsets were validated in a second cohort. This network was abundant in a subset of patients, independent of IBD subtype, severity or intestinal location. Putative disease-associated CD4⁺ T cells were detectable in blood. Finally, imaging-mass cytometry revealed the spatial colocalization of neutrophils, memory CD4⁺ T cells and myeloid cells in the inflamed intestine. Our study indicates that a cellular network of both innate and adaptive immune cells colocalizes in inflamed biopsies from a subset of patients. These results contribute to dissecting disease heterogeneity and may guide the development of targeted therapeutics in IBD.

FOXP3 variants are independently associated with transforming growth factor Β1 plasma levels in female patients with inflammatory bowel disease

OBJECTIVE

The aim of this study was to evaluate the association of -924 G>A (rs2232365) and -3279 C>A (rs3761548) FOXP3 variants with IBD susceptibility, clinical and endoscopic activity, and IL-10 and TGF-β1 plasma levels.

METHOD

The study included 110 IBD female patients, 60 with Ulcerative Colitis (UC) and 50 with Crohn's Disease (CD), and 154 female controls. FOXP3 variants were determined with Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP). Plasma levels of IL-10 and TGF-β1 were determined using immunofluorimetric assay.

RESULTS

AA genotype of rs2232365 and rs3761548 was associated with CD (OR = 3.147, 95% CI 1.015-9.758, p = 0.047) and UC (OR = 3.221, 95% CI 1.050-9.876, p = 0.041) susceptibility, respectively. However, were not associated with TGF-β1 and IL-10 levels, and endoscopic/clinical activity disease. GAGA haplotype was associated with IBD (OR = 4.003, 95% CI 1.100-14.56, p = 0.035) and UC susceptibility (OR = 6.107, 95% CI 1.609-23.18, p = 0.008). In addition, IBD patients with the GAGA haplotype had lower TGF-β1 levels (p = 0.041). Moreover, G/C haplotype (dominant model) had a protective effect of 60% in CD susceptibility and lower Endoscopic Severity Index.

CONCLUSIONS

These results suggest that FOXP3 variants could exert a role in the Treg, which could be one of the factors involved in the susceptibility and pathogenesis of IBD.

Precision Medicine in Pediatric Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) describes a heterogenous group of diseases characterized by chronic inflammation of the intestinal tract. The IBD subtypes, Crohn's disease, ulcerative colitis, and IBD-Unspecified, each have characteristic features, but heterogeneity remains even among the subtypes. There has been an explosion of new knowledge on the possible pathogenesis of IBD over the last 2 decades mirroring innovation and refinement in technology, particularly the generation of large scale - "-omic" data. This knowledge has fostered a veritable renaissance of novel diagnostics, prognostics, and therapeutics, with patients with IBD seeing hope bloom in the increasingly large armamentarium of IBD therapies. However, while there are increased numbers of therapies and more pathways being targeted, the number of medications for IBD is still finite and the efficacy has reached a plateau. Precision medicine (PM) is much needed to rationally select and optimize IBD therapies in the new reality of wider but still limited choice with a concurrent, increasingly fine resolution on the significance and utility of clinical, genetic, microbial, and proteomic characteristics that define individual patients. PM is a rapidly changing art, but this review will strive to detail the current state and future directions of PM in pediatric IBD.

Genetic Variants of DMBT1 and SFTPD and Disease Severity in Paediatric Inflammatory Bowel Disease—A Polish Population-Based Study

Deleted in malignant brain tumours 1 protein (DMBT1) and surfactant protein D (SFTPD) are antimicrobial peptides previously linked to inflammatory bowel disease (IBD) susceptibility. This study attempts to link the most potential IBD-associated polymorphisms in DMBT1 and SFTPD with the disease severity in children. A total of 406 IBD patients (Crohn’s disease (CD) n = 214 and ulcerative colitis (UC) n = 192) were genotyped using hydrolysis probe assay. Clinical expression was described by disease activity scales, albumin and C-reactive protein levels, localisation and behaviour (Paris classification), systemic steroid, immunosuppressive, biological, and surgical treatment, number of exacerbation-caused hospitalisations, relapses and nutritional status. IBD patients with the risk genotype (AA) in DMBT1 rs2981804 had more frequent biological treatment (AA: vs. AG/GG; p = 0.012), concomitant diseases (AA vs. AG vs. GG; p = 0.015) and cutaneous manifestations (AA vs. AG/GG, p = 0.008). In UC, rs2981804 genotypes might be linked with albumin concentrations at diagnosis (AA vs. AG vs. GG; p = 0.009). In CD, DMBT1 rs2981745 was significantly associated with the number of severe relapses per year of disease (p = 0.020) and time-to-immunosuppression (p = 0.045). SFTPD was seemingly found to be associated with age at first immunosuppression in IBD (CC vs. CT vs. TT; p = 0.048). In conclusion, selected polymorphisms of DMBT1 and SFTPD might be associated with some disease severity measures in children with IBD. However, the magnitude of associations and their clinical relevance might be minor.

Are We Ready to Include Prognostic Factors in Inflammatory Bowel Disease Trials?

Inflammatory bowel disease (IBD) is a chronic inflammatory disease characterized by periodic episodes of flares and remission. Treatment is aimed at healing the bowel, to ultimately decrease hospitalization rates, need for surgeries and overall disability. In more recent years, treatment has transitioned from a reactive approach to a more proactive approach focusing on treating disease earlier and preventing complications. The challenge lies in identifying patients who need more intensive treatment early and trying to determine who will respond to which medications. Biomarkers and clinical activity scoring systems can be used to help guide treatment decisions. However, IBDs are very heterogeneous and the significance of these biomarkers can be difficult to discern on an individual basis. Recently, prognostic tools have been developed to aid in determining a patient's prognosis as well as their likelihood to respond to different therapies. Despite this progress, clinical trials have not routinely adopted this approach in their study design. Tools for stratification of disease severity and to personalize treatment choices have the potential to improve our studies both by enriching the patient population and further guiding clinical decision making in practice. This review aims to discuss biomarkers, current prognosticating tools, tools that determine response to therapy and how incorporating these into clinical trials will be beneficial.

The Role of Early Biologic Therapy in Inflammatory Bowel Disease

The goals for treatment of inflammatory bowel diseases (IBDs) are changing from elimination of symptoms toward complete disease control-a process that demands both clinical and endoscopic remission. This new IBD treatment paradigm has been shifting from a conventional "step-up" approach toward a more "top-down" early intervention treatment strategy. Recent studies suggest that the use of biologic agents, specifically those targeting tumor necrosis factor alpha, earlier in the treatment course improves patient outcomes and can prevent progression to irreversible bowel damage. Although the strategy of early intervention has accumulating evidence in Crohn's disease, there is less evidence supporting its impact in ulcerative colitis.

Review article: the genetics of the human leucocyte antigen region in inflammatory bowel disease

BACKGROUND

The human leucocyte antigen (HLA) complex, located at chromosome 6p21.3 is a highly polymorphic region containing the classical class I and II HLA genes. The region is highly associated with inflammatory bowel disease (IBD), largely through genome-wide association studies (GWAS).

AIMS

To review the role of HLA in immune function, summarise data on risk/protective HLA genotypes for IBD, discuss the role of HLA in IBD pathogenesis, treatment and examine limitations that might be addressed by future research.

METHODS

An organised search strategy was used to collate articles describing HLA genes in IBD, including Crohn's disease and ulcerative colitis.

RESULTS

All classical HLA genes with variation (including HLA-A, B, C, DRB1, DQA1, DQB1, DPA1 and DPB1) harbour IBD-associated genotypes. The most implicated gene is HLA-DRB1, with HLA-DRB1*03:01 the most associated risk allele in both Crohn's disease and ulcerative colitis. Elucidating precise disease associations is challenging due to high linkage disequilibrium between HLA genotypes. The mechanisms by which risk alleles cause disease are multifactorial, with the best evidence indicating structural and electrostatic alteration impacting antigen binding and downstream signalling. Adverse medication events have been associated with HLA genotypes including with thiopurines (pancreatitis) and anti-TNF agents (antibody formation).

CONCLUSIONS

The HLA complex is associated with multiple risk/protective alleles for IBD. Future research utilising long-read technology, ascertainment of zygosity and integration in disease modelling will improve the functional understanding and clinical translation of genetic findings.

Contribution of susceptibility variants at FCGR2A and 13q12 to the risk of relapse among Japanese patients with ulcerative colitis

BACKGROUND

Recent genome-wide association studies have identified nearly 100 susceptibility genes for ulcerative colitis (UC). However, the contribution of susceptibility variants for UC to clinical outcome has scarcely been reported. The aim of this study was to investigate whether UC-associated genetic variants confer a risk of clinical relapse.

METHODS

One hundred and nine consecutive Japanese subjects with quiescent UC were recruited. Four genetic variants of HLA-DRB1*1502, rs6671847 at FCGR2A, rs17085007 at 13q12, and rs2108225 at SLC26A3 were genotyped by Invader assay. The clinical courses were followed after blood sampling, and the risk of relapse according to these genotypes was calculated by Cox proportional hazard model.

RESULTS

During the mean follow-up period of 35 months (range 1-81 months), 49 of 109 subjects (45 %) relapsed. Carriers of the G allele of rs6671847 showed an increased risk of relapse compared with non-carriers [adjusted hazard ratio (HR), 2.27; 95 % confidence interval (CI), 1.20-4.32; p = 0.01]. Patients with the CT or TT genotypes of rs17085007 also had an increased risk of relapse compared to subjects with the CC genotype (for CT: adjusted HR, 2.16; 95 % CI, 1.10-4.23; p = 0.03; for TT: adjusted HR, 3.25; 95 % CI, 1.18-8.95; p = 0.02). These two risk variants multiplied the risk of relapse by 2.74 times (95 % CI, 1.10-4.23; p = 0.01) in patients with one risk genotype and 5.40 times (95 % CI, 2.06-14.13; p = 0.0006) in patients with both risk genotypes.

CONCLUSIONS

Genetic variants of rs6671847 at FCGR2A and rs17085007 at 13q12 conferred a risk of relapse in patients with UC.

The use of prognostic factors in inflammatory bowel diseases

The disease spectrum and natural course of Crohn's disease and ulcerative colitis are highly variable. The majority of Crohn's disease patients will require surgery at a certain stage in their disease compared to only a fraction of the ulcerative colitis patients. Similarly, some patients are destined to experience an indolent disease course while others will require early intensive therapy. Ideally, these subtypes of patients should be identified as early as possible with the help of reliable prognostic factors in order to guide personalized therapeutic decisions. In this review, the authors focused on the most relevant reports on the use of different prognostic factors to predict disease course, postoperative recurrence and response to therapy in patients with inflammatory bowel disease. The last 15 years have seen a wealth of novel genetic and serological markers of disease severity. Nevertheless, none of these markers have proven to be superior to careful clinical phenotyping and endoscopic features early in the disease course. Future attempts should apply an integrated approach that unites clinical, serological and (epi)genetic information with environmental influences, with a clear focus on the microbiome to ultimately identify molecular-based and clinically relevant subgroups.

Predicting outcomes in acute severe ulcerative colitis

Response to corticosteroid treatment in acute severe ulcerative colitis (ASUC) has changed very little in the past 50 years. Predicting those at risk at an early stage helps stratify patients into those who may require second line therapy or early surgical treatment. Traditionally, risk scores have used a combination of clinical, radiological and biochemical parameters; established indices include the 'Travis' and 'Ho' scores. Recently, inflammatory bowel disease genetic risk alleles have been built into models to predict outcome in ASUC. Given the multifactorial nature of inflammatory bowel disease pathogenesis, in the future, composite scores integrating clinical, biochemical, serological, genetic and other '-omic' data will be increasingly investigated. Although these new genetic prediction models are promising, they have yet to supplant traditional scores, which remain the best practice. In this modern era of rescue therapies in ASUC, robust scoring systems to predict failure of ciclosporine and infliximab must be devised.

Immunogenetic biomarkers in inflammatory bowel diseases: Role of the IBD3 region

Many studies have demonstrated the linkage between the IBD3 region (6p21.1-23), an area which encompasses the famous human leukocyte antigen (HLA) complex, and Crohn’s disease (CD) or ulcerative colitis (UC). IBD3 is the only region that meets genome-wide significance, and provides stronger evidence of the linkage than 16p13.1-16q12.2 (IBD1), the locus that contains the susceptibility gene CARD15. However, despite these findings, IBD3 susceptibility genes remain elusive and unclear due to the strong linkage disequilibrium, extensive polymorphism, and high gene density that characterize this area and also due to varying allele frequencies in populations around the world. This area presents an extremely high abundance of genes, including the classical and non-classical major histocompatibility complex (MHC) class I and II genes, and other genes, namely MHC class III genes tumor necrosis factor (TNF)-α and -β, and Hsp, whose proteins play key functions in immunological processes. To date, it is not clear which genes within the MHC family contribute to the IBD pathogenesis, although certain HLA alleles have been associated with IBD. Recent insights into the biological function of other genes encoded within the IBD3 region, such as the MHC class I chain-related (MIC) genes, have led investigators to a more comprehensive exploration of this region. MHC class I chain-related molecule A (MICA) is highly polymorphic and interacts with NKG2D, its receptor on the surface of NK, Tγδ and T CD8⁺ cells. Increased expression of MICA in intestinal epithelial cells and increased expression of NKG2D in CD4⁺ T cells (lamina propria) in patients with CD have also been reported. MICA alleles have also been associated with IBD, and a variation at amino acid position 129 of the α2-heavy chain domain seems to categorize MICA alleles into strong and weak binders of NKG2D receptor, thereby influencing the effector cells’ function. In this regard, a relevant role of MICA-129-Val/Met single nucleotide polymorphism has recently been implicated in the pathogenesis of IBD. TNF-α and -β also play an important role in inflammatory response. In fact, IBD is commonly treated with TNF-α inhibitors. Additionally, polymorphisms of TNF-α gene are known to affect the gene expression level and particular TNF-α genotypes may influence the response of IBD patients treated with TNF-α inhibitors.

Characteristics of Japanese inflammatory bowel disease susceptibility loci

BACKGROUND

There are substantial differences in inflammatory bowel disease (IBD) genetics depending on the populations examined. We aimed to identify Japanese population-specific or true culprit susceptibility genes through a meta-analysis of past genetic studies of Japanese IBD.

METHODS

For this study, we reviewed 2,703 articles. The review process consisted of three screening stages: we initially searched for relevant studies and then relevant single nucleotide polymorphisms (SNPs). Finally, we adjusted them for the meta-analysis. To maximize our chances of analysis, we introduced proxy SNPs during the first stage. To minimize publication bias, no significant SNPs and solitary SNPs without pairs were combined to be reconsidered during the third stage. Additionally, two SNPs were newly genotyped. Finally, we conducted a meta-analysis of 37 published studies in 50 SNPs located at 22 loci corresponding to the total number of 4,853 Crohn's disease (CD), 5,612 ulcerative colitis (UC) patients, and 14,239 healthy controls.

RESULTS

We confirmed that the NKX2-3 polymorphism is associated with common susceptibility to IBD and that HLA-DRB1*0450 alleles increase susceptibility to CD but reduce risk for UC while HLA-DRB1*1502 alleles increase susceptibility to UC but reduce CD risk. Moreover, we found individual disease risk loci: TNFSF15 and TNFα to CD and HLA-B*5201, and NFKBIL1 to UC. The genetic risk of HLA was substantially high (odds ratios ranged from 1.54 to 2.69) while that of common susceptibility loci to IBD was modest (odds ratio ranged from 1.13 to 1.24).

CONCLUSIONS

Results indicate that Japanese IBD susceptibility loci identified by the meta-analysis are closely associated with the HLA regions.

Can we predict the high-risk patient?

BACKGROUND

While therapeutic strategies able to change the natural history of inflammatory bowel diseases (IBD) are being developed, factors predicting aggressive disease are needed to be able to choose the appropriate therapeutic strategy for the individual patient based on the risk/benefit ratio. The aim of this review is to focus on the tools assisting the clinician in routine practice regarding the prediction of disease evolution.

METHODS

A literature review was performed, which was mainly based on PubMed search, using the following terms: Crohn's disease, ulcerative colitis, inflammatory bowel disease, genetics, serology, biomarkers, endoscopy, C-reactive protein, faecal calprotectin, disease evolution and complications.

RESULTS

For the prediction of disease evolution, clinical characteristics, particularly disease location and behaviour, are probably currently the most useful. In addition, a series of biomarkers, including genetic, serological and inflammatory markers, as well as characteristics of endoscopic lesions may have an added value.

CONCLUSIONS

Simple clinical, biological and endoscopic tools may help the clinician in predicting disease evolution in IBD. However, these tools are still insufficient, and prospective evaluation of new genetic and biological markers are needed.

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.

Towards personalized care in IBD

The expanding knowledge of the role of genetic variants involved in the susceptibility to IBD heralds an era of disease categorization beyond Crohn's disease and ulcerative colitis. A more robust molecular definition of the spectrum of IBD subtypes is likely to be based on specific molecular pathways that determine not only disease susceptibility but also disease characteristics such as location, natural history and therapeutic response. Evolving diagnostic panels for IBD will include clinical variables and genetic markers as well as other indicators of gene function and interaction with environmental factors, such as the microbiome. Multimodal algorithms that combine clinical, serologic and genetic information are likely to be useful in predicting disease course. Variation in IBD-susceptibility and drug-related pathway genes seems to influence the response to anti-TNF therapy. Furthermore, gene expression signatures and composite models have both shown promise as predictors of therapeutic response. Ultimately, models based on combinations of genotype and gene expression data with clinical, biochemical, serological, and microbiome data for clinically meaningful subgroups of patients should permit the development of tools for individualized risk stratification and treatment selection.

Role of genes, the environment and their interactions in the etiology of inflammatory bowel diseases

Few of the studied genes demonstrate association with inflammatory bowel disease (IBD). Three mutations in the nucleotide-binding oligomerization domain 2 gene have consistently shown to be independent risk factors for Crohn's disease, but none of the alleles exhibited high sensitivity or specificity for IBD. Linkage analysis implicated several loci on various chromosomes, and epistasis has been demonstrated. The etiopathogenesis of IBD remains unknown, and environmental contribution to their pathogenesis is evident from genetic studies that demonstrated incomplete monozygotic twins concordandance rate for both Crohn's and ulcerative colitis. Smoking has shown an opposite effect on disease phenotype, with an adverse effect on disease course for Crohn's disease, but a slight beneficial effect in ulcerative colitis. The contribution of infectious agents to susceptibility to IBD appears to be strong. However, the role of nutrition on the etiology and therapy of IBD is not clear. Inconsistencies in environmental risk factors could be due to gene-environment interactions, making it essential to study the role of genetics and environmental contribution to the etiopathology of IBD. Transgenic or knockout mice, such as interleukin-10(-/-), T-cell receptor alpha(-/-), Galphai(2) (-/-) and N-cadherin(-/-), develop colitis-like inflammation similar to humans. Therefore, animal models must be further studied to explore mechanistic interactions.

Ethnicity differences in genetic susceptibility to ulcerative colitis: a comparison of Indian asians and white northern Europeans

BACKGROUND

Studies in Caucasian populations have identified a number of genetic associations with ulcerative colitis (UC), but reports from other ethnic groups have been limited. Recent studies from India have reported an association with UC and a single polymorphism (SNP) in CARD15/NOD2 (SNP5, rs2066842), which has not been reported in Caucasian UC cohorts. In addition, strong genetic associations with SNPs in the HLA region have been reported in Indian UC populations. However, there have been no reports on the frequency of HLA class II alleles in Indian populations with inflammatory bowel disease to examine whether the associations differ from other ethnic populations.

METHODS

Genotyping was performed for 137 Indian UC patients for HLA class II alleles (HLA-DRB1*1502 & HLA-DRB1*0103), IL23R (rs11209026), and CARD15/NOD2 (rs2066842). The genetic data were compared with 204 healthy Indian controls and 50 white European UC patients.

RESULTS

The HLA-DRB1*0103 allele was absent in all Indian UC patients and controls in contrast to white European UC patients (9/50: 18%). The HLA-DRB1*1502 allele was significantly more frequent in the Indian UC cohort (29.2%) than controls (17.6%) (P = 0.04) and the allele was absent in the white European cohort. There were no significant differences in the frequency of the CARD15/NOD2 (rs2066842) variant or IL23R (rs11209026) between the different ethnic groups.

CONCLUSIONS

The HLA-DRB1*0103 allele is rare or absent in the Indian Asian population but HLA-DRB1*1502 is positively associated with UC. Further genetic studies in this population could provide valuable information and may help distinguish the degree of influence of genetic and environmental pathogenic factors.

Have genomic discoveries in inflammatory bowel disease translated into clinical progress?

Inflammatory bowel disease (IBD) is a heterogeneous disease that can be challenging to diagnose and manage. As a result, significant efforts have been made in attempting to identify clinical, genomic, and serologic markers of disease that can aid in patient assessment and treatment. Recent genomic discoveries have the potential to change clinical practice by identifying those susceptible to IBD, predict natural history and guide choice of therapy. Panels of genetic and genomic markers are more likely to emerge as clinical tools, as opposed to individual allelic variants. Serology and biomarkers are already being used and guiding management but await integration with genomic panels before achieving their maximal potential. This article reviews the current state of IBD genetics and evolving molecular approaches that may have potential clinical impact.

Gene expression profiling of CD8+ T cells predicts prognosis in patients with Crohn disease and ulcerative colitis

Crohn disease (CD) and ulcerative colitis (UC) are increasingly common, chronic forms of inflammatory bowel disease. The behavior of these diseases varies unpredictably among patients. Identification of reliable prognostic biomarkers would enable treatment to be personalized so that patients destined to experience aggressive disease could receive appropriately potent therapies from diagnosis, while those who will experience more indolent disease are not exposed to the risks and side effects of unnecessary immunosuppression. Using transcriptional profiling of circulating T cells isolated from patients with CD and UC, we identified analogous CD8+ T cell transcriptional signatures that divided patients into 2 otherwise indistinguishable subgroups. In both UC and CD, patients in these subgroups subsequently experienced very different disease courses. A substantially higher incidence of frequently relapsing disease was experienced by those patients in the subgroup defined by elevated expression of genes involved in antigen-dependent T cell responses, including signaling initiated by both IL-7 and TCR ligation - pathways previously associated with prognosis in unrelated autoimmune diseases. No equivalent correlation was observed with CD4+ T cell gene expression. This suggests that the course of otherwise distinct autoimmune and inflammatory conditions may be influenced by common pathways and identifies what we believe to be the first biomarker that can predict prognosis in both UC and CD from diagnosis, a major step toward personalized therapy.

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.

Regulation of major histocompatibility complex class II gene expression, genetic variation and disease

Major histocompatibility complex (MHC) class II molecules are central to adaptive immune responses and maintenance of self-tolerance. Since the early 1970s, the MHC class II region at chromosome 6p21 has been shown to be associated with a remarkable number of autoimmune, inflammatory and infectious diseases. Given that a full explanation for most MHC class II disease associations has not been reached through analysis of structural variation alone, in this review we examine the role of genetic variation in modulating gene expression. We describe the intricate architecture of the MHC class II regulatory system, indicating how its unique characteristics may relate to observed associations with disease. There is evidence that haplotype-specific variation involving proximal promoter sequences can alter the level of gene expression, potentially modifying the emergence and expression of key phenotypic traits. Although much emphasis has been placed on cis-regulatory elements, we also examine the role of more distant enhancer elements together with the evidence of dynamic inter- and intra-chromosomal interactions and epigenetic processes. The role of genetic variation in such mechanisms may hold profound implications for susceptibility to common disease.

The future of molecular approaches to inflammatory bowel disease

Technological advances in genomics and transcriptomics have resulted in the introduction of molecular tests into the clinical arena. Despite established uses of such tests in the oncology field, their integration into the management of complex diseases has not been widely evaluated. Progress in the field of inflammatory bowel disease (IBD) genetics has been rapid in recent years, and these advances have provided more urgent impetus to investigating the role of molecular tests in IBD. This article summarizes the current state of molecular testing available for IBD, and the potential utility of such tests as research in the area widens.

MICB0106 gene polymorphism is associated with ulcerative colitis in central China

BACKGROUND

The highly polymorphic nonclassical MHC class I chain-related genes A and B (MICA and MICB) encode stress-inducible glycoproteins expressed on various epithelial cells including intestinal epithelial cells. MICA and MICB gene polymorphisms and expressions are associated with autoimmune diseases but not known in ulcerative colitis (UC).

AIMS

To investigate the association of MICB exon 2-4 polymorphisms and soluble MICA (sMICA) expression with the susceptibility of UC in central China.

MATERIALS AND METHODS

Genomic DNA was isolated from peripheral blood. The allele frequencies of MICB exon 2-4 were genotyped in 105 UC patients and 213 healthy controls by PCR single-stranded conformation polymorphism method. Thirty-two patients and 32 controls were selected for determining serum sMICA expression by ELISA.

RESULTS

Allele frequency of MICB0106 was significantly higher in UC patients than in healthy controls (19.0% vs. 8.9%, corrected P (Pc) = 0.0006), especially in patients with extensive colitis (24.4% vs. 8.9%, Pc = 0.0006), moderate and severe disease (24.1% vs. 8.9%, Pc = 0.0006), extraintestinal manifestations (20.5% vs. 8.9%, Pc = 0.012), male patients (22.1% vs. 8.0%, Pc = 0.006), and patients over the age of 40 years (28.8% vs. 8.3%, Pc = 0.0006). The sMICA level was significantly higher in UC than in healthy controls (604.41 +/- 480.43 pg/ml vs. 175.37 +/- 28.31 pg/ml, P = 0.0001) but not associated with the MICB0106 genotypes.

CONCLUSIONS

Overall, MICB0106 allele was positively associated with UC in the Han Chinese in central China. sMICA was highly expressed in UC but not associated with the MICB0106 genotype.

Advances in research on gene polymorphisms in ulcerative colitis

The morbidity of ulcerative colitis is associated with gene polymorphisms. Genome-wide association studies have identified many ulcerative colitis-predisposing genes. In this article, we will review the recent advances in research on gene polymorphisms in ulcerative colitis by providing an overview of high-frequency predisposing genes and new predisposing genes for ulcerative colitis.

Mapping of multiple susceptibility variants within the MHC region for 7 immune-mediated diseases

The human MHC represents the strongest susceptibility locus for autoimmune diseases. However, the identification of the true predisposing gene(s) has been handicapped by the strong linkage disequilibrium across the region. Furthermore, most studies to date have been limited to the examination of a subset of the HLA and non-HLA genes with a marker density and sample size insufficient for mapping all independent association signals. We genotyped a panel of 1,472 SNPs to capture the common genomic variation across the 3.44 megabase (Mb) classic MHC region in 10,576 DNA samples derived from patients with systemic lupus erythematosus, Crohn's disease, ulcerative colitis, rheumatoid arthritis, myasthenia gravis, selective IgA deficiency, multiple sclerosis, and appropriate control samples. We identified the primary association signals for each disease and performed conditional regression to identify independent secondary signals. The data demonstrate that MHC associations with autoimmune diseases result from complex, multilocus effects that span the entire region.

HLA and autoimmune digestive disease: a clinically oriented review for gastroenterologists

OBJECTIVES

The human leukocyte antigen (HLA) system includes genes involved in graft-vs-host rejection and in immune response. The discovery that HLAs are associated with several diseases led to appealing developments both in basic biomedical research and in clinical medicine, and offered the opportunity to improve the understanding of pathogenesis and classification of diseases, as well as to provide diagnostic and prognostic indicators. The aim of this article is to review the association between HLA alleles and autoimmune digestive disease and its current relationship with modern HLA nomenclature and clinical practice.

METHODS

Articles dealing with the association between HLAs and autoimmune digestive disease (including celiac disease, inflammatory bowel disease, autoimmune hepatitis, sclerosing cholangitis and primary biliary cirrhosis) were searched for using Pubmed and SCOPUS databases from earliest records to January 2008.

RESULTS

The review has provided two sections. In the first, we explain the basic principles of HLA structure, function, and nomenclature, as an introduction to the second section, which describes current associations between HLA alleles and digestive diseases. The clinical implications of each HLA association are critically discussed. Actually, a clinical role for HLA typing is suggested for only a few conditions, e.g., celiac disease.

CONCLUSIONS

The knowledge of current HLA nomenclature and of its association with some digestive diseases such as celiac disease can be useful in clinical practice for diagnostic and prognostic purposes. This can avoid improper HLA typing as well as stressing the need for further studies on other possible clinical applications.

Clinical and molecular characteristics of isolated colonic Crohn's disease

BACKGROUND

Clinical, serological, and molecular data support the existence of discrete subsets of Crohn's disease (CD) defined by location of disease. Little is known about the epidemiology and natural history of isolated CD of the colon (Montreal Classification L2) because most studies have not accurately distinguished it from ileocolonic disease. Our objectives were to describe the clinical features and natural history of isolated colonic CD in a rigorously characterized patient cohort and to investigate the association of polymorphisms in a number of genes with colonic location of disease and disease behavior.

METHODS

Patients with L2 disease were identified from a database of 675 CD patients. Only patients with a normal small bowel enema (70%), ileoscopy alone (30%), or both (20%) were included. Genotyping was performed using PCR-SSP or the iPLEX platform.

RESULTS

In all, 135 patients were classified with L2 disease. L2 disease was more common in women (74.0% versus 58.0%; P = 0.0004; odds ratio [OR] = 2.11, 95% confidence interval [CI] 1.36-3.26) and in never smokers (48.9% versus 36.9%; P = 0.008; OR = 1.64, 95% CI 1.09-2.45); 20.7% underwent colonic resection for severe disease. We confirmed that carriage of the HLA-DRB1*0103 allele is strongly associated with isolated colonic CD (14.9% versus 4.0%; P = 0.000016; OR 4.6, 95% CI 2.25-9.47) and report the novel association of this allele with time to first surgical event (log rank P = 0.001). There was no association with any of the known CD susceptibility loci (NOD2, IBD5, NOD1, IL23R, ATG16L1) and isolated colonic CD. A nonsynonymous polymorphism in MEKK1 (rs832582) was associated with CD susceptibility overall (15% versus 19%; P = 0.0083; OR = 1.28, 95% CI 1.07-1.54). The association was strongest in those patients not carrying a NOD2 mutation and had no effect on disease location.

CONCLUSIONS

This study describes the clinical features of isolated colonic CD and demonstrates the importance of the HLA region in determining the molecular basis of colonic inflammation.

HLA-DRB1 alleles influence clinical phenotypes in Japanese patients with ulcerative colitis

The human leukocyte antigen (HLA) region has been implicated in the disease susceptibility of inflammatory bowel disease by several linkage and association studies. In Caucasians, HLA-DRB1 has been reported to determine the clinical phenotypes of ulcerative colitis (UC). Others and we previously reported that HLA-DRB1*1502 was strongly associated with UC in the Japanese population. However, the contribution of HLA-DRB1 to the clinical phenotypes in Japanese UC has not been elucidated yet. The aim of this study was to determine whether HLA-DRB1 alleles were associated with the clinical phenotypes in Japanese patients with UC. A total of 353 patients with UC were recruited. Patients were classified into subgroups by sex, age at diagnosis, disease extent, need for steroid therapy or need for surgical treatment. The allele frequency of HLA-DRB1*08 was significantly higher in patients whose disease extended beyond the rectum (left-sided and extensive UC) than in those with proctitis [odds ratio (OR)=2.20, Pc=0.043). The allele frequency of HLA-DRB1*09 was significantly higher in patients with UC diagnosed at the age of 40 years or older than in those with UC diagnosed before the age of 40 years (OR=2.31, Pc=0.022). Besides these positive associations, no significant differences were found in the allele frequencies between the other subgroups. We conclude that HLA-DRB1*09 is associated with the age at diagnosis and HLA-DRB1*08 is associated with the disease extent of UC in Japanese. These results indicate that HLA-DRB1 is not only associated with the overall UC susceptibility but also associated with the clinical phenotypes in Japanese.

Association of IL23R, TNFRSF1A, and HLA-DRB1*0103 allele variants with inflammatory bowel disease phenotypes in the Finnish population

BACKGROUND

Crohn's disease (CD) and ulcerative colitis (UC), 2 major forms of inflammatory bowel disease (IBD), are complex disorders with significant genetic predisposition. The first CD-associated gene, CARD15/NOD2, was recently identified and since then several reports on novel IBD candidate genes have emerged. We investigated disease phenotype association to genetic variations in IL23R, ATG16L1, DLG5, ABCB1/MDR1, TLR4, TNFRSF1A, chromosome 5 risk haplotype including SLC22A4 and SLC22A5, and HLA-DRB1*0103 allele among Finnish IBD patients.

METHODS

A total of 699 IBD patients were genotyped for disease-associated variants by polymerase chain reaction (PCR) and restriction enzyme digestion or Sequenom iPLEX method.

RESULTS

Five markers spanning the IL23R gene were associated with CD. The SNP (single nucleotide polymorphism) rs2201841 gave the strongest association (P = 0.002). The rare HLA-DRB1*0103 allele was found to associate with UC (P = 0.008), and the TNFRSF1A A36G variant was associated with familial UC (P = 0.007). Upon phenotypic analysis we detected association between familial UC and rare TNFRSF1A alleles 36G and IVS6+10G (P = 0.001 and P = 0.042, respectively). In addition, IL23R markers were associated with stricturing CD (P = 0.010-0.017), and ileocolonic CD was more prevalent in the carriers of the same 2 TNFRSF1A variants (P = 0.021 and P = 0.028, respectively). Less significant genotype-phenotype associations were observed for the TLR4 and HLA variants.

CONCLUSIONS

We were able to replicate the association of the IL23R variants with CD as well as HLA-DRB1*0103 with UC; confirmation of TNFRSF1A association with UC needs additional studies. Our findings also suggest that polymorphisms at IL23R and TNFRSF1A, and possibly HLA and TLR4, loci may account for phenotypic variation in IBD.

Defining the role of the MHC in autoimmunity: a review and pooled analysis

The major histocompatibility complex (MHC) is one of the most extensively studied regions in the human genome because of the association of variants at this locus with autoimmune, infectious, and inflammatory diseases. However, identification of causal variants within the MHC for the majority of these diseases has remained difficult due to the great variability and extensive linkage disequilibrium (LD) that exists among alleles throughout this locus, coupled with inadequate study design whereby only a limited subset of about 20 from a total of approximately 250 genes have been studied in small cohorts of predominantly European origin. We have performed a review and pooled analysis of the past 30 years of research on the role of the MHC in six genetically complex disease traits - multiple sclerosis (MS), type 1 diabetes (T1D), systemic lupus erythematosus (SLE), ulcerative colitis (UC), Crohn's disease (CD), and rheumatoid arthritis (RA) - in order to consolidate and evaluate the current literature regarding MHC genetics in these common autoimmune and inflammatory diseases. We corroborate established MHC disease associations and identify predisposing variants that previously have not been appreciated. Furthermore, we find a number of interesting commonalities and differences across diseases that implicate both general and disease-specific pathogenetic mechanisms in autoimmunity.

Strong protective effect of DR3 against ulcerative colitis in the Spanish population

OBJECTIVES

Ulcerative colitis (UC) is a chronic inflammatory disease affecting the colon. Major histocompatibility complex (MHC) on the short arm of human chromosome 6 has been thoroughly studied as a susceptibility locus. However, one of the strongest MHC associations found, that of HLA-DR3 with UC protection, has not been observed in all populations. Our aim in the present study was to evaluate this negative association in a large cohort of Spanish UC patients and controls, and to try to elucidate which, if any, of the diverse DR3 haplotypes (identified by TNFa and b microsatellites, located in the MHC class III region) is most tightly associated (negatively) with the disease.

METHODS

A total of 537 UC patients and 748 healthy controls from Spain were included in the present study. Low-resolution DR genotyping was performed by PCR and hybridization with allele-specific oligonucleotide probes. TNFa and b microsatellites were studied in a subset of samples (279 UC patients and 503 healthy controls) by PCR followed by capillary electrophoresis. DR-TNFa-TNFb haplotypes were estimated by the expectation-maximization algorithm and comparisons were performed by a chi2 test.

RESULTS

After a stepwise procedure, the only DR alleles significantly associated with the disease were DR3 (very strongly, protection) and DR4 (weakly, protection). The strong protective effect of DR3 was evenly distributed among the haplotypes DR3-TNFa1b5, DR3-TNFa2b3, and DR3-TNFother.

CONCLUSIONS

Our results confirm the strong protective effect of DR3 in our population, and suggest that the relevant protective gene is located centromeric to TNFa and TNFb markers in the MHC region.

The 8.1 ancestral MHC haplotype is strongly associated with colorectal cancer risk

Many recent data indicate that some alleles encoded in the central major histocompatibility complex (MHC) region (Class III) of short arm of chromosome 6 may modify the risk of cancer development. Therefore we determined 4 single nucleotide polymorphisms (SNPs) of this region (TNF-alpha -308 G > A, RAGE -429 T > C, HSP70-2 -1267 A > G, LTA 252 A > G) in genomic DNA samples from 183 Hungarian patients with colorectal cancer and 141 age matched control subjects representing the Hungarian population of the same age and gender. No significant differences were found in either SNP tested. When, however, three- or four-locus haplotypes consisting of known constituents of the so-called 8.1 ancestral haplotype (8.1AH) were considered, marked differences were observed. Frequency of TNF-alpha -308A, RAGE -429C, HSP70-2 -1267G, LTA 252G (8.1AH) haplotype was significantly (p = 0.006) more frequent (19.1%) among patients than in the controls (7.7%). Age- and gender-adjusted ratio of the 8.1AH carriers vs. non-carriers to have colorectal cancer was 2.514 (1.130-5.594). This risk was higher in <or=67 years old subjects (4.073 (1.317-12.596)) and in females (3.771 (1.302-10.927). These findings-consistent with similar recent results with ovarian cancer-indicate that carriers of the 8.1AH, encoding for an altered immune response and known to be associated with alterations of several immune functions and autoimmune diseases have an increased risk for some cancer types. These findings may contribute to better understanding how the defense mechanisms against tumors could be enhanced/strengthened.

Late-breaking news from the "4th International Meeting on Inflammatory Bowel Diseases" Capri, 2006

At the "4th International Meeting on Inflammatory Bowel Diseases: on the Way to New Therapies," Capri, 2006, genetics, bacteria-host interactions, immunomodulation, and tissue response were discussed deeply in order to understand, rationalize, and develop novel therapies. About genetics, the importance of a better understanding of the nature of known loci and of the putative associations was stressed. It was confirmed that genotype-phenotype associations in inflammatory bowel disease (IBD) have important clinical and therapeutic implications. The importance of the search for dominant bacterial antigens in chronic immune-mediated intestinal inflammation emerged, as well as knowledge of cellular and molecular mechanisms of bacterial-host interactions. It was discussed how innate and adaptive immunity signaling events can perpetuate chronic inflammation. Signal transduction pathways provide an intracellular mechanism by which cells respond and adapt to environmental stress. The identification of these signals have led to a greater understanding of the pathogenesis of IBD and pointed to potential therapeutic targets. It was shown that immune homeostasis is lost in IBD, resulting in a complex tissue response involving the action of immune and nonimmune cells. The nonimmune tissue response in IBD could be regarded as a new target for control of chronic intestinal inflammation. The changing role of biotherapy in IBD was widely discussed and in particular the anti-TNF-alpha monoclonal antibodies. Granulocyte-colony stimulating factor (GM-CSF) and stem cells therapies were also discussed. The risk-to-benefit ratio of the novel therapies was analyzed in detail. Finally, future directions for basic science and the unmet needs for clinical practice were presented.

The role of TNFalpha in ulcerative colitis

Standard of care for ulcerative colitis involves long-term pharmacotherapy or colectomy. Approximately 20% to 30% of patients eventually require a colectomy because patients either do not respond or cannot tolerate the currently available pharmacotherapies. Advances in our knowledge of the pathophysiology of ulcerative colitis have highlighted the importance of cytokines such as tumor necrosis factor alpha (TNFalpha) in the inflammatory process. TNFalpha is a proinflammatory mediator that plays an integral role in the pathogenesis of inflammatory bowel disease. In addition, mounting evidence indicates a genetic association between TNFalpha and ulcerative colitis. Furthermore, increased TNFalpha levels have been demonstrated in studies of patients with ulcerative colitis. TNFalpha is likely an important component in the pathophysiology of ulcerative colitis, and thus agents targeting TNFalpha in ulcerative colitis have been studied. Recent randomized controlled trials have confirmed that biologic anti-TNFalpha therapy is effective in ulcerative colitis. Soluble TNFalpha receptors or biologic agents that suppress or inhibit TNFalpha production may also show therapeutic promise.

Combined HLA-DR and -DQ disparity is associated with a stable course of ulcerative colitis after liver transplantation for primary sclerosing cholangitis

Combined disparity of human leukocyte antigen (HLA)-DR and -DQ between mother and fetus is associated with less severe ulcerative colitis (UC) during pregnancy. We evaluated whether donor-recipient HLA disparity after liver transplantation (LT) affects UC in patients with primary sclerosing cholangitis (PSC). Sixty-nine consecutive patients with PSC underwent LT; all underwent colonoscopy before LT; 48 had UC before and 3 had de novo UC after LT. Clinical and laboratory data, activity and treatment of UC, post-LT cytomegalovirus infection, and disparity of HLA-A, -B, -DR, and -DQ for each donor-recipient pair were evaluated. Pre-LT quiescent UC was present in 26 patients. Post-LT UC activity was evaluated in 36 of 51 patients with UC who had not undergone pre-LT colectomy and who had >12 months' post-LT survival. Of these, 16 were stable, 17 had worsened, and 3 had de novo UC. Seven required colectomy (4 for dysplasia or cancer) after LT. Post-LT cytomegalovirus viremia was neither associated with worse UC activity (P = 0.58) nor de novo UC. Disparity with respect to HLA-A, -B, -DR, and -DQ was found in 58%, 27%, 44%, and 39% donor-recipient pairs, respectively. Post-LT UC course was similar with respect to single HLA disparity. However, disparity in none or only one HLA-DR or -DQ was significantly associated with worse activity compared with patients with disparity at both (65% vs. 0%, P = 0.009). Logistic regression found that the disparity for both -DR and -DQ was the only factor statistically significantly associated with post-LT UC activity. We conclude that disparity in both HLA-DR and -DQ between donor and recipient is associated with stable UC activity after LT.

Attitudes toward genetic testing in patients with inflammatory bowel disease

OBJECTIVES

Significant progress has been observed in our understanding of the role of genetics in inflammatory bowel disease susceptibility and phenotype. The clinical role of genetic testing for inflammatory bowel disease is not well developed, but may become important as more susceptibility genes are found. The aim of this study was to evaluate the attitudes of patients with inflammatory bowel disease toward genetic testing.

METHODS

Two hundred and fifty patients (108 ulcerative colitis, 142 Crohn's disease) attending the outpatient clinic completed a questionnaire regarding clinical and family history data, as well as their attitudes toward genetic testing for inflammatory bowel disease.

RESULTS

Ninety percent (225/250) of all patients expressed an interest in undergoing genetic testing themselves, with 87.6% (219/250) also expressing a desire for their children to be tested. Although the proportion of ulcerative colitis and Crohn's disease patients interested in testing was similar, levels of interest decreased as the predictive value of a putative genetic test decreased. A comparable proportion of those with [80/86 (93.0%)] and those without [145/164 (88.4%)] a family history of inflammatory bowel disease expressed an interest in genetic testing. More patients who had received immunomodulating or biologic therapies [123/128 (96.1%)], however, wished to undergo testing than those who had not received these medications [78/93 (83.9%; P<0.01)].

CONCLUSION

Patients with inflammatory bowel disease have a high level of interest in genetic testing, both for themselves and for their children, and this will have an impact upon the provision of genetic services as progress is made toward defining a clinical role for inflammatory bowel disease susceptibility genes.

Different HLA class II associations in ulcerative colitis patients with and without primary sclerosing cholangitis

Approximately 80% of patients with primary sclerosing cholangitis (PSC) of Northern European origin have inflammatory bowel disease (IBD), the majority ulcerative colitis (UC). An inherent problem in interpreting positive findings in genetic association studies of PSC is thus to distinguish between factors associated with hepatobiliary versus intestinal pathology. We aimed to clarify to what extent human leukocyte antigen (HLA) class II associations in UC patients with and without PSC differ. High-resolution DRB1 and DQB1 typing was performed in 365 Scandinavian PSC patients, an independent cohort of 330 Norwegian UC patients and 368 healthy controls. HLA associations found in PSC were mostly distinct from those seen in UC, and no significant differences were noted between PSC patients with concurrent UC and PSC patients without IBD. This suggests different HLA associated genetic susceptibility to PSC and UC, and supports notions that UC in PSC may represent a distinct UC phenotype.

Epistatic interaction between FCRL3 and MHC in Spanish patients with IBD

Inflammatory bowel disease (IBD), which comprises ulcerative colitis (UC) and Crohn's disease (CD), shows a multifactorial origin, with genetic and environmental factors involved. Although the genetic influence is clear for both diseases, the genetics involved is complex and epistatic interactions with other genes probably exist. The Fc receptor-like 3 gene (FCRL3) maps to the human chromosome 1q21-22 and certain single nucleotide polymorphisms (SNPs) in its promoter have been associated with some autoimmune diseases. Our aim was to study the role of two promoter SNPs of the FCRL3 gene (-169A>G, rs7528684 and -110C>T, rs11264799) in patients with IBD and their interaction with HLA-DRB1 and CARD15 in patients with UC and CD, respectively. A case-control study with 311 patients with CD, 324 patients with UC and 497 healthy controls was performed. All the individuals were White Spaniards. No significant associations were found between any FCRL3 SNP and CD or UC, but the stratification in patients with UC by human leukocyte antigen (HLA) showed a significant increase in heterozygosity at the FCRL3 locus, especially -169 AG (AG vs AA+GG, P= 0.0027, odds ratio = 3.6, 95% confidence interval 1.4-2.9), when HLA-DRB1*0103 carrier patients were compared with HLA-DRB1*0103 noncarriers. Our data suggest an epistatic interaction between genes in chromosomes 6p21 and 1q21-22, marked, respectively, by HLA-DRB1*0103 and FCRL3-169 AG.

Response to corticosteroids in severe ulcerative colitis: a systematic review of the literature and a meta-regression

BACKGROUND & AIMS

Colectomy is a potentially life-saving procedure for patients with severe attacks of UC who fail medical therapy. We aimed to systematically review studies that reported the short-term colectomy rate in severe UC or reported variables that could predict treatment failure.

METHODS

We conducted a systematic literature search for cohort studies and controlled trials published between 1974-2006.

RESULTS

Thirty-two studies met the inclusion criteria; 16 reported short-term outcome and predictors of therapy failure, 13 only outcome, and 3 only predictors. In the pooled analysis, 581 of 1991 patients required colectomy (weighted mean 27; 95% confidence interval [CI], 26%-28%), and 22 died (1%; 95% CI, 0.7%-1.5%). In a heterogeneity-controlled meta-regression, colectomy rate did not change during the last 30 years (R(2) = 0.07, P = .8). Cyclosporine was used in only 100 patients, with a 51% (95% CI, 41%-60%) short-term success rate. A second meta-regression failed to demonstrate a dose-colectomy response of methylprednisolone therapy beyond 60 mg daily (R(2) < 0.01, P = .98). More than 20 variables were identified in 19 studies to predict medical therapy failure, but only a few were consistently reproduced: disease extent, stool frequency, temperature, heart rate, C-reactive protein, albumin, and radiologic assessment.

CONCLUSIONS

The short-term colectomy rate in severe UC has remained stable during the last 30 years, despite the introduction of cyclosporine, which was not used frequently. We could not find any support for administering methylprednisolone at a higher dose than 60 mg/day. Variables that predict outcome of corticosteroid therapy could aid in the development of guidelines for introduction of rescue therapies in severe UC.

Molecular pathogenesis of inflammatory bowel disease: genotypes, phenotypes and personalized medicine

Crohn's disease (CD) and ulcerative colitis (UC), also known as inflammatory bowel diseases (IBD), are characterized by chronic inflammation of the gastrointestinal tract. IBD is among the few complex diseases for which several genomic regions and specific genes have been identified and confirmed in multiple replication studies. We will review the different loci implicated in disease risk in the context of three proposed mechanisms leading to chronic inflammation of the gut mucosa: 1) deregulation of the innate immune response to enteric microflora or pathogens; 2) increased permeability across the epithelial barrier; and 3) defective regulation of the adaptive immune system. As our knowledge of genetic variation, analytical approaches and technology improves, additional genetic risk factors are expected to be identified. With the identification of novel risk variants, additional pathophysiological mechanisms are likely to emerge. The resulting discoveries will further our molecular understanding of IBD, potentially leading to improved disease classification and rational drug design. Moreover, these approaches and tools can be applied in the context of variable drug response with the goal of providing more personalized clinical management of patients with IBD.

What is the origin of ulcerative colitis? Still more questions than answers

Despite more than a century of existence as a clinical entity, the true origin of ulcerative colitis still remains elusive. Several factors probably contribute to the development of this condition. Recently discovered technologies have clarified the role of bacterial species, which may account for intestinal dysbiosis, as a factor triggering ulcerative colitis. Genetic susceptibility together with abnormal innate immunoreactivity probably comprise the essential prerequisites for the initiation and perpetuation of ulcerative colitis. Although the genetic background has been more clearly recognised in patients with Crohn's disease than in those with ulcerative colitis, some candidate loci associated with ulcerative colitis have also been intensively studied. Additionally, environmental factors may interfere with inherent predispositions to ulcerative colitis, and either suppress or reinforce them. Whatever the origin, the search for the aetiology of ulcerative colitis must have the same goal: the improvement of treatment and the quality of life in patients with ulcerative colitis.

Anti-donor DR103 Immunization in a DRB1*0101 kidney allograft recipient

Posttransplant appearance of donor-specific anti-HLA antibodies is correlated with poor graft survival. Herein, we have provided evidence that an HLA-DRB1*0101 kidney allograft recipent developed anti-DR103 antibody after receiving a transplant from a HLA-DRB1*0103 cadaveric donor, resulting in graft loss. HLA-DRB1*0103 is a rare allele in Caucasian populations. It differs from DRB1*0101 only by three amino-acid substitutions and may play a central role in allorecognition. Nevertheless, our data showed that it induced alloimmunization in a DRB1*0101 recipient. Therefore, this new possibility of immunization must be taken into account before transplantation as well as after grafting.

Genetic variants and the risk of Crohn's disease: what does it mean for future disease management?

Genetic research in inflammatory bowel disease, especially in Crohn's disease, has made significant progress during recent years. There have been > 10 total genome scans that have been performed, and susceptibility loci on several chromosomes have been identified. Together with candidate gene studies, these scans have led to the identification of several susceptibility genes, with CARD15 being the most important. These genetic data have already provided important insights into the pathophysiology of inflammatory bowel disease and are stimulating future research. On the other hand, genotype-phenotype associations have illustrated the heterogenic nature of the disease. Although the clinical application of this knowledge is so far limited, there is significant optimism that an individual management of patients based on genetic data will be possible in the near future.

Genetics of inflammatory bowel disease: The role of the HLA complex

The human leucocyte antigen (HLA) complex on chromosome 6p21.3 is the most extensively studied genetic region in Inflammatory bowel disease (IBD). Consistent evidence of linkage to IBD3 (6p21.1-23), an area which encompasses the HLA complex, has been demonstrated for both Crohn’s disease and ulcerative colitis, and a number of replicated associations with disease susceptibility and phenotype have recently emerged. However, despite these efforts the HLA susceptibility gene (s) for IBD remain elusive, a consequence of strong linkage disequilibrium, extensive polymorphism and high gene density across this region. This article reviews current knowledge of the role of HLA complex genes in IBD susceptibility and phenotype, and discusses the factors currently limiting the translation of this knowledge to clinical practice.