IL23R variation determines susceptibility but not disease phenotype in inflammatory bowel disease

Increased prevalence of gout in patients with inflammatory bowel disease: A population-based study

Background and Aim

Arthritis is a recognized extra-intestinal manifestation of inflammatory bowel disease (IBD). Studies show altered uric acid metabolism in IBD. This study aims to investigate the association between IBD and gout.

Methods

We used a multi-center database (Explorys Inc.) consisting of data from several US healthcare systems. We identified adults diagnosed with Crohn's disease (CD) and ulcerative colitis (UC) between 1999 and 2022. In this cohort, we identified patients diagnosed with gout. We collected demographic data and identified patients diagnosed with IBD-associated arthritis and those who had intestinal resection. Risk factors associated with gout were collected. Multivariate analysis was used.

Results

Out of the 69 260 780 patients in the database, we identified 209 020 patients with UC (0.30%) of whom 9130 had gout (4.3%). Additionally, 249 480 had CD (0.36%) of whom 14 000 had gout (5.61%). Males were more prevalent in the UC and gout group than in the CD and gout group (58% vs 51%). After adjustment, CD was significantly associated with gout (odds ratio [OR] 1.68, confidence interval [CI]: 1.60-1.75). UC was also significantly associated with gout (OR 1.38, CI: 1.31-1.44). In subgroup analysis with intestinal resection, CD patients who had intestinal resection had higher association with gout versus those without surgery (OR 2.34, CI: 2.25-2.43). Similar increase was observed in the UC group with intestinal resection (OR 1.53, CI: 1.49-1.56).

Conclusion

IBD is strongly associated with gout, with higher correlation observed with CD. Intestinal resection is associated with an increase in the risk of gout. Patients with IBD who present with new-onset arthritis should be investigated for gout.

Composition and diverse differences of intestinal microbiota in ulcerative colitis patients

Objective

To explore the composition of the intestinal microbiota in ulcerative colitis (UC) patients and to identify differences in the microbiota between patients with active disease and those in remission.

Methods

Between September 2020 and June 2021, we enrolled into our study, and collected stool samples from, patients with active UC or in remission and healthy control subjects. The diagnosis of UC was based on clinical, endoscopic, radiological, and histological findings. The composition of the intestinal microbiota was determined by sequencing of the 16S rRNA V3–V4 region and by bioinformatic methods. The functional composition of the intestinal microbiota was predicted using PICRUSt 2 (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) software.

Results

We found that the intestinal flora was significantly less rich and diverse in UC patients than in healthy control subjects. Beta diversity analysis revealed notable differences in the intestinal flora compositions among the three groups, but there was no statistical difference in alpha diversity between UC patients with active disease and those in remission. At the phylum level, the relative abundances of Proteobacteria and Patescibacteria were significantly higher, and the relative abundances of Desulfobacterota and Verrucomicrobiota were lower, in UC patients with active disease than in the healthy control group. Higher levels of potential pathogens and lower levels of butyrate-producing bacteria were also detected in UC patients with active disease. Linear discriminant analysis Effect Size (LefSe) revealed that 71 bacterial taxa could serve as biomarkers, with 26 biomarkers at the genus level. In addition, network analysis showed that there was a positive correlation between Roseburia and Lachnospira. Functional predictions indicated that gene functions involving the metabolism of some substances, such as methane, lipopolysaccharide, geraniol, and ansamycins, were significantly different among the three groups.

Conclusion

The richness and diversity of the intestinal microbiota differed significantly among the three groups. Richness describes the state of being rich in number of intestinal bacteria, whereas diversity is the number of different species of intestinal bacteria. Different bacterial taxa could be used as biomarkers, expanding our understanding of the relationship between the intestinal microbiota microenvironment and UC in the future.

Multi-omics analyses of the ulcerative colitis gut microbiome link Bacteroides vulgatus proteases with disease severity

Ulcerative colitis (UC) is driven by disruptions in host-microbiota homoeostasis, but current treatments exclusively target host inflammatory pathways. To understand how host-microbiota interactions become disrupted in UC, we collected and analysed six faecal- or serum-based omic datasets (metaproteomic, metabolomic, metagenomic, metapeptidomic and amplicon sequencing profiles of faecal samples and proteomic profiles of serum samples) from 40 UC patients at a single inflammatory bowel disease centre, as well as various clinical, endoscopic and histologic measures of disease activity. A validation cohort of 210 samples (73 UC, 117 Crohn's disease, 20 healthy controls) was collected and analysed separately and independently. Data integration across both cohorts showed that a subset of the clinically active UC patients had an overabundance of proteases that originated from the bacterium Bacteroides vulgatus. To test whether B. vulgatus proteases contribute to UC disease activity, we first profiled B. vulgatus proteases found in patients and bacterial cultures. Use of a broad-spectrum protease inhibitor improved B. vulgatus-induced barrier dysfunction in vitro, and prevented colitis in B. vulgatus monocolonized, IL10-deficient mice. Furthermore, transplantation of faeces from UC patients with a high abundance of B. vulgatus proteases into germfree mice induced colitis dependent on protease activity. These results, stemming from a multi-omics approach, improve understanding of functional microbiota alterations that drive UC and provide a resource for identifying other pathways that could be inhibited as a strategy to treat this disease.

Inflammatory bowel disease manifestations in spondyloarthritis: considerations for the clinician

INTRODUCTION

Spondyloarthropathies (SpA) are a group of inflammatory arthritis that can involve the spine and/or peripheral joints. Extra-articular manifestations, such as inflammatory bowel disease (IBD), are frequently observed within the clinical manifestations of SpA and are part of the SpA classification criteria. Evidence of IBD is observed in about 6-7% of SpA patients, and a silent, microscopic gut inflammation, could be present in up to 50% of patients. From a pathogenetic point of view, dysregulated microbiome and migration of T lymphocytes and other cells from gut to the joint ('gut-joint' axis) has been recognized, in the context of a common genetic background.

AREAS COVERED

The aim of this paper is to narratively review the recent evidences on the epidemiology, classification, clinical findings, pathogenesis, diagnosis, and treatment of IBD in patients with SpA and to provide advices for both rheumatologist and gastroenterologist in the management of IBD in SpA.

EXPERT OPINION

IBD manifestations in SpA frequently increase the burden of the disease and represent a clinical challenge, especially for the diagnosis, assessment, and treatment of patients affected by those conditions. New treatment strategies targeting both articular and intestinal manifestations are now available and may lead to a better outcome.

Inflammatory and mitogenic signals drive interleukin 23 subunit alpha (IL23A) secretion independent of IL12B in intestinal epithelial cells

The heterodimeric cytokine interleukin-23 (IL-23 or IL23A/IL12B) is produced by dendritic cells and macrophages and promotes the proinflammatory and regenerative activities of T helper 17 (Th17) and innate lymphoid cells. A recent study has reported that IL-23 is also secreted by lung adenoma cells and generates an inflammatory and immune-suppressed stroma. Here, we observed that proinflammatory tumor necrosis factor (TNF)/NF-κB and mitogen-activated protein kinase (MAPK) signaling strongly induce IL23A expression in intestinal epithelial cells. Moreover, we identified a strong crosstalk between the NF-κB and MAPK/ERK kinase (MEK) pathways, involving the formation of a transcriptional enhancer complex consisting of proto-oncogene c-Jun (c-Jun), RELA proto-oncogene NF-κB subunit (RelA), RUNX family transcription factor 1 (RUNX1), and RUNX3. Collectively, these proteins induced IL23A secretion, confirmed by immunoprecipitation of endogenous IL23A from activated human colorectal cancer (CRC) cell culture supernatants. Interestingly, IL23A was likely secreted in a noncanonical form, as it was not detected by an ELISA specific for heterodimeric IL-23 likely because IL12B expression is absent in CRC cells. Given recent evidence that IL23A promotes tumor formation, we evaluated the efficacy of MAPK/NF-κB inhibitors in attenuating IL23A expression and found that the MEK inhibitor trametinib and BAY 11-7082 (an IKKα/IκB inhibitor) effectively inhibited IL23A in a subset of human CRC lines with mutant KRAS or BRAFV600E mutations. Together, these results indicate that proinflammatory and mitogenic signals dynamically regulate IL23A in epithelial cells. They further reveal its secretion in a noncanonical form independent of IL12B and that small-molecule inhibitors can attenuate IL23A secretion.

The Unsolved Link of Genetic Markers and Crohn's Disease Progression: A North American Cohort Experience

BACKGROUND

While progress has been made in the identification of Crohn's disease (CD) susceptibility loci, efforts to identify a genetic basis for disease progression have been less fruitful. The specific aim of this study was to build upon the major genetic advances made in IBD by applying genome-wide technologies toward predicting disease progression in CD.

METHODS

Crohn's disease cases (n = 1495) from 3 IBD centers were reviewed by experienced physicians. Clinical and demographic details were collected, focusing on the time to first disease progression. Genome-wide association (GWA) analysis was carried out on 3 clinical outcomes: 1) time to disease progression; 2) time to first abdominal surgery; and 3) a binary analysis of indolent vs progressive disease. Cox-proportional hazard and logistic regression models were used.

RESULTS

A GWA analysis was carried out to determine any genetic variation associated with the time to disease progression; 662 cases were included after quality control (QC) and exclusion of any cases with B2/B3 behavior at baseline (n = 450). There were 1360 cases included after QC in the time to abdominal surgery analysis. No variant reached genome-wide significance in any of the 3 analyses performed. Eight known IBD susceptibility single nucleotide polymorphism (SNPs) were found to be associated with time-to-abdominal surgery SMAD3 (rs17293632), CCR6 (rs1819333), CNTF (rs11229555), TSPAN14 (rs7097656), CARD9 (rs10781499), IPMK (rs2790216), IL10 (rs3024505), and SMURF1 (rs9297145) (P < 0.05).

CONCLUSION

Our GWA study failed to show any SNP-phenotype association reaching genome-wide significance. It is likely that multiple variables affect disease progression, with genetic factors potentially having only a small effect size.

Biomarkers in Inflammatory Bowel Disease-Associated Spondyloarthritis: State of the Art and Unmet Needs

Inflammatory bowel disease-associated spondyloarthritis is a systemic disease characterized by the chronic inflammation of both the gastrointestinal tract and the musculoskeletal system. Since inflammatory bowel disease-associated spondyloarthritis has been associated with a significant diagnostic delay, which may lead to poor quality of life and progression of joint damage, efforts to discover new reliable and noninvasive diagnostic biomarkers have been made. We reviewed the state of the art of biomarker research in inflammatory bowel disease-associated spondyloarthritis, showing that to date it has been largely unsatisfactory. Only a few of the biomarkers that have been investigated are likely to enter the clinical practice upon further validation in independent cohorts. The research of new and innovative biomarkers for inflammatory bowel disease-associated spondyloarthritis is warranted.

Relationship between the IL23R SNPs and Crohn's Disease Susceptibility and Phenotype in the Polish and Bosnian Populations: A Case-Control Study

It is suggested that IL-23/IL-17 axis and single nucleotide polymorphisms (SNPs) of IL23R may have crucial role in pathogenesis of Crohn’s disease (CD). Thus, we sought to assess the IL23R SNPs contribution to susceptibility and phenotype of CD. We recruited 117 CD subjects and 117 controls from Poland and 30 CD subjects and 30 controls from Bosnia and Herzegovina (B&H). Two common IL23R SNPs: rs1004819, rs7517847 were genotyped using TaqMan SNP assays. In the Polish population it was found that allele rs1004819: A increases the risk of CD, while allele rs7517847: A is protective against disease development. In Poles the co-carriage of two IL23R risk genotypes was associated with increased risk of CD. A significantly increased risk of CD early onset was observed in Poles carrying at least one rs7517847: G allele. It was also found that IL23R SNPs may be associated with structuring/penetrating CD behavior, as alleles rs1004819: A and rs7517847: G were significantly less frequent in patients without complications, from Poland and B&H, respectively. Allele rs1004819: A was also significantly more frequent in Poles with penetrating CD. These results confirm IL23R SNPs contribution to CD susceptibility in the Polish population and suggest their impact on early age of onset and more severe disease course.

Association of IL23R Variants With Crohn's Disease in Korean Children

Background: The interleukin 23 receptor gene (IL23R) is strongly associated with Crohn's disease (CD). It is unknown whether genetic variations in IL23R determine susceptibility for pediatric CD in Asian populations. Here, we investigated the association between IL23R variants and CD in Korean children. Methods: Four single nucleotide polymorphisms (SNPs) of IL23R [rs76418789 (G149R), rs1004819, rs7517847, and rs1495965] were genotyped in 141 children with CD and 150 controls using DNA direct sequencing. The risk allele and genotype frequencies were compared between patients and controls. The association between clinical phenotypes and genotypes of patients was also analyzed. Results: Two IL23R SNPs, rs76418789 (G149R), and rs1495965, were associated with CD in Korean pediatric patients as defense and risk loci, respectively. The odds ratio (OR) for rs76418789 (G149R) and rs1495965 was 0.409 (95% confidence interval [CI], 0.177-0.944; p = 0.031) and 1.484 (95% CI, 1.070-2.059; p = 0.018), respectively. Patients with the homozygous G allele of rs1495965 showed higher CD risk than those with other genotypes (GG vs. AA: OR, 2.256; 95% CI, 1.136-4.478; p = 0.019; GG vs. GA+AA: OR, 2.000; 95% CI, 1.175-3.404; p = 0.010). Additionally, they were more likely to have relatively invasive disease behavior of stenosis and/or penetration than simple inflammation (OR, 2.297; 95% CI, 1.065-4.950; p = 0.032). Conclusions: This is the first study reporting IL23R variants in Asian pediatric patients with CD. IL23R was significantly associated with Korean pediatric CD, and the rs1495965 may influence the clinical features of CD in Korean children.

Analysis of the association of single nucleotide polymorphisms of interleukin-23 receptor (IL-23R) and inflammatory bowel disease in a Chinese Han cohort

Inflammatory bowel disease (IBD) is a chronic, complex genetic disease with rapidly increasing prevalence in China. The interactions of genetic, environmental, and microbial factors contribute to the development of IBD, however, the precise etiologies of IBD are not well understood yet. Interleukin-23 receptor (IL-23R) encodes a subunit of receptor for IL-23, which is an important proinflammatory cytokine. In this study, we investigated the relationship between the single nucleotide polymorphism (SNP) of IL-23R gene and IBD in Chinese Han population. We genotyped three nonsynonymous IL-23R SNPs with amino acid changes (rs11209026, p.Arg381Gln; rs41313262 p.Val362Ile and rs11465797 p.Thr175Asn) in 198 patients with IBD (124 UC and 74 CD) and 100 healthy controls. The prevalence of the A allele in IL-23R Arg381Gln of CD appeared less than controls, but it was not statistically significant (2.70% vs. 6.00%, p > 0.05). There was no statistical difference between UC and controls (5.65% vs. 6.00%, p = 0.91). The p.Val362Ile variant was present in 2.42% of UC patients, in 2.70% of CD patients, which was similar in the control (2.00%). There was no statistical difference among these three groups. We did not detect Thr175Asn (rs11465797 c.524 C>A) in all the three groups. In conclusion, our study demonstrated that the p.Val362Ile and Arg381Gln were not associated with susceptibility to IBD in Chinese Han population.

Association of single nucleotide polymorphisms of IL23R and IL17 with necrotizing enterocolitis in premature infants

Necrotizing enterocolitis (NEC) is a severe gastrointestinal inflammatory disease in neonates, particularly in preterm infants. The interleukin (IL) 23/IL17 axis has been shown to play an important role in the gastrointestinal inflammation. However, the association of gene polymorphisms in the IL23/IL17 axis and the development of NEC remains unknown. In this study, we aimed to explore a possible genetic role of IL23R and IL17 in the development of NEC. We identified single nucleotide polymorphisms (SNPs) in IL23R (rs10889677), IL17A (rs2275913), and IL17F (rs763780) by polymerase chain reaction and Sanger sequencing. A total of 102 NEC patients (stage II, n = 75; and stage III, n = 27) and 120 control subjects were recruited for the study. All of the participants were premature (gestational age < 37 weeks). Our results revealed that the combination of the IL17F rs763780 (TC + CC) genotype and the C allele both significantly increased the risk of NEC [odds ratio (OR) 1.89, 95% confidence interval (CI) 1.04-3.43, P = 0.035; OR 1.82, 95% CI 1.06-3.13, P = 0.028, respectively]. Furthermore, the rs763780 (TC + CC) genotype was associated with increased severity of NEC and the incidence of NEC-related perforation [OR 2.80, 95% CI 1.10-7.12, P = 0.031; OR 3.86, 95% CI 1.10-13.53, P = 0.035, respectively]. However, IL23R rs10889677 and IL17A rs2275913 were not associated with the susceptibility to NEC. In conclusion, our data suggest that a variant of IL17F (rs763780) may contribute to the development of NEC.

IL-23R mutation is associated with ulcerative colitis: A systemic review and meta-analysis

OBJECTIVES

Since a genome-wide association study revealed that Interleukin-23 receptor (IL-23R) gene is a candidate gene for Ulcerative Colitis (UC), many studies have investigated the association between the IL-23R polymorphisms and UC. However, the results were controversial. The aim of the study was to determine whether the IL-23R polymorphisms confer susceptibility to UC.

METHODS

A systematic literature search was carried out to identify all potentially relevant studies. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were used to estimate the strength of association.

RESULTS

A total of 33 studies in 32 articles, including 10,527 UC cases and 15,142 healthy controls, were finally involved in the meta-analysis. Overall, a significant association was found between all UC cases and the rs11209026A allele (OR = 0.665, 95% CI = 0.604~0.733, P < 0.001). Similarly, meta-analyses of the rs7517847, rs1004819, rs10889677, rs2201841, rs11209032, rs1495965, rs1343151 and rs11465804 polymorphisms also indicated significant association with all UC (all P < 0.05). Stratification by ethnicity revealed that the rs11209026, rs7517847, rs10889677, rs2201841 andrs11465804 polymorphisms were associated with UC in the Caucasian group, but not in Asians, while the rs1004819 and rs11209032 polymorphisms were found to be related to UC for both Caucasian and Asian groups. However, subgroup analysis failed to unveil any association between the rs1495965 and rs1343151 polymorphisms and UC in Caucasians or Asians.

CONCLUSIONS

The meta-analysis suggests significant association between IL-23R polymorphisms and UC, especially in Caucasians.

MicroRNAs: how many in inflammatory bowel disease?

PURPOSE OF REVIEW

MicroRNAs (miRNAs), small noncoding RNA molecules of approximately 22 nucleotides, have emerged as critical mediators of gene expression. As the dysregulation of gene expression can have far reaching impact on health and disease, miRNAs are being examined as potent new mediators of disease as either biomarkers or potential therapeutic targets. The purpose of this review is to evaluate the contribution of miRNAs to inflammatory bowel disease (IBD) pathophysiology.

RECENT FINDINGS

Recent studies have evaluated the expression of miRNAs in tissue and body fluid specimens from patients with the main subtypes of IBD - Crohn's disease and ulcerative colitis. Unique miRNA expression patterns that may distinguish IBD subtypes have been uncovered.

SUMMARY

Significant progress has been made in illuminating the complex interactive networks of miRNAs and gene targets in IBD. The potential use of miRNAs as disease biomarkers or therapeutics shows promise. However, there are still significant hurdles to overcome before miRNA-based therapeutics and diagnostics will be of clinical utility.

Association of rs11209032 and rs1004819 Polymorphisms in Interleukin-23 Receptor Gene With Ankylosing Spondylitis

Objectives

This study aims to investigate the distribution of human leukocyte antigen B27 (HLA-B27) alleles (+/-) and interleukin-23 receptor (IL-23R) gene rs11209032 and rs1004819 polymorphisms among ankylosing spondylitis (AS) patients in a Turkish cohort.

Patients and methods

The study sample comprised 106 AS patients (89 males, 18 females; mean age 38.9±10 years; range 19 to 65 years) and 82 healthy controls (70 males, 12 females; mean age 32.15±7.07 years; range 19 to 51 years). Distribution of HLA-B27 alleles (+)/(-) in AS patients were observed by reverse hybridization technique. Genotyping of IL-23R rs11209032 and rs1004819 polymorphisms of AS patients and healthy controls were performed by real time polymerase chain reaction.

Results

Of the AS patients, 69 (65.1%) were HLA-B27 positive. Distribution of rs11209032 genotype frequencies in AS group were 31.1% for GG, 50.9% for GA, and 17.9% for AA; while in control group, it was 34.1% for GG, 53.7% for GA, and 12.2% for AA. Distribution of rs1004819 genotype frequencies in AS group were 30.2% for CC, 52.8% for CT, and 17.0% for TT; while in control group, it was 42.7% for CC, 46.3% for CT, and 11.0% for TT. There was no significant difference between AS patients and controls in terms of genotype frequencies of IL-23R gene rs11209032 and rs1004819 polymorphisms.

Conclusion

No association was found between AS and IL23R rs11209032 and rs1004819 polymorphisms in this Turkish AS cohort.

Protective role of R381Q (rs11209026) polymorphism in IL-23R gene in immune-mediated diseases: A comprehensive review

Interleukin-23 (IL-23) is a regulator of cellular immune responses involved in controlling infection and autoimmune diseases. Strong evidence has shown that IL-23 plays a role in the maintenance of immune responses by influencing the proliferation and survival of IL-17-producing T-helper (TH)-17 cells. The critical role of the IL-23/TH17 axis in immune-mediated diseases has emerged from different studies. It has also been seen that polymorphisms in the IL-23 receptor (IL-23R) gene might influence IL-23 responses. Interestingly, a functional single nucleotide polymorphism (SNP) in the IL-23 receptor gene (IL-23R; rs11209026, 1142 G wild-type A reduced function, Arg381Gln, R381Q) seems to confer a measure of protection against development of inflammatory bowel disease (IBD; Crohn's disease, ulcerative colitis), ankylosing spondylitis, rheumatoid arthritis, psoriasis, thyroiditis, recurrent spontaneous abortion and asthma, suggesting that a perturbation in the IL-23 signaling pathway is likely to be relevant to the pathophysiology of these diseases. The aim of this review was to provide an evaluation of what is currently known about the protective role of R381Q variant in IL-23R gene in immune-based diseases.

Interferon regulatory factor 5 in human autoimmunity and murine models of autoimmune disease

Interferon regulatory factor 5 (IRF5) has been demonstrated as a key transcription factor of the immune system, playing important roles in modulating inflammatory immune responses in numerous cell types including dendritic cells, macrophages, and B cells. As well as driving the expression of type I interferon in antiviral responses, IRF5 is also crucial for driving macrophages toward a proinflammatory phenotype by regulating cytokine and chemokine expression and modulating B-cell maturity and antibody production. This review highlights the functional importance of IRF5 in a disease setting, by discussing polymorphic mutations at the human Irf5 locus that lead to susceptibility to systemic lupus erythematosus, rheumatoid arthritis, and inflammatory bowel disease. In concordance with this, we also discuss lessons in IRF5 functionality learned from murine in vivo models of autoimmune disease and inflammation and hypothesize that modulation of IRF5 activity and expression could provide potential therapeutic benefits in the clinic.

Association of Interleukin-23 receptor gene polymorphisms with susceptibility to Crohn's disease: A meta-analysis

Studies investigating the association between Interleukin-23 receptor (IL-23R) gene polymorphisms and Crohn’s disease (CD) report conflicting results. Thus, a meta-analysis was carried out to assess the association between the IL-23R polymorphisms and CD. A systematic literature search was conducted to identify all relevant studies. Pooled odds ratio (ORs) with 95% confidence interval (CIs) was used to estimate the strength of association. Finally, a total of 60 case-control studies in 56 articles, involving 22,820 CD patients and 27,401 healthy controls, were included in the meta-analysis. Overall, a significant association was found between all CD and the rs7517847 polymorphism (OR = 0.699, 95% CI = 0.659 ~ 0.741, P < 0.001). Meta-analysis of the rs11209026, rs1343151, rs10489629 and rs11465804 polymorphisms indicated the same pattern as for rs7517847. Meta-analysis showed an association between the rs10889677A allele and CD (OR = 1.393, 95% CI = 1.328 ~ 1.461, P < 0.001). Similarly, meta-analysis of the rs2201840, rs1004819, rs1495965 and rs11209032 polymorphisms revealed the same pattern as that shown by meta-analysis of rs10889677. Stratification by ethnicity revealed that IL-23R gene polymorphisms were associated with CD in the Caucasian group, but not in Asians. In summary, the meta-analysis suggests a significant association between IL-23R polymorphisms and CD, especially in Caucasians.

Interleukin-23 receptor genetic polymorphisms and ulcerative colitis susceptibility: A meta-analysis

OBJECTIVE

The interleukin-23 receptor (IL-23R) polymorphism has been implicated in susceptibility to ulcerative colitis (UC), but the results remain inconclusive. This study was designed to evaluate whether IL-23R polymorphisms were associated with UC susceptibility.

METHODS

CNKI, WanFang Data, PubMed, MEDLINE, Web of Science, Google Scholar, EBSCO, CBM database and EMBASE were searched until 31 June 2014 for eligible studies on eight IL-23R polymorphisms: rs11209026, rs7517847, rs1209032, rs2201841, rs1343151, rs1088967, rs1495965 and rs1004819. Meta-analysis from all eligible case-control studies was performed to assess the purported associations. Meta-analysis was performed by using the RevMan 5.2 software and STATA package version 12.0.

RESULTS

Sixteen studies with 5438 cases and 7380 controls were included. Overall, our analysis found that variant minor alleles for single nucleotide polymorphisms (SNPs) rs11209026 (Arg381Gln) (dominant model: GG+TG vs. TT, P=0.02, OR=0.71, 95%CI: 0.53-0.94); rs7517847 (recessive model: GG vs. TT, P=0.04, OR=0.80, 95%CI: 0.65-0.99) and rs11209032 [dominant model: GA+AA vs. GG (P=0.04, OR=1.31, 95% CI: 1.01-1.26); AA vs. GG: (P=0.04, OR=1.21, 95% CI: 1.01-1.45)] of IL-23R were associated with UC risk. In stratification analysis by ethnicity, we observed that the rs11209026 and rs7517847 polymorphism of IL-23R could protect against development of UC among Caucasian populations [rs11209026: dominant model (P=0.01, OR=0.69, 95%CI: 0.52-0.92); rs7517847: GG vs. TT (P=0.002, OR=0.69, 95%CI: 0.54-0.87); recessive model (P=0.004, OR=0.73, 95% CI: 0.59-0.90)]; the rs11209032 were associated with a greater risk for UC in Caucasian populations [dominant model (P=0.04, OR=1.13, 95%CI: 1.00-1.26)]; the rs1088967 were associated with a lower risk for UC among Asian populations [dominant model (P=0.04, OR=0.73, 95%CI: 0.54-0.99)]. Moreover, meta-analysis revealed no association between the four alleles of the rs2201841, rs1004819, rs1495965 and rs1343151 polymorphisms and the risk of developing UC in Caucasian and Asian populations.

CONCLUSION

Our meta-analysis supports that two polymorphisms (rs11209026 and rs7517847) in the IL-23 gene may be considered to be protective factors against developing UC among Caucasian populations; while the rs11209032 polymorphisms may increase the risk of UC among Caucasian populations; furthermore, the rs1088967 polymorphisms in the IL-23 gene may be considered to be protective factors against developing UC among Asian populations. Further large case-control studies especially concerning ethnicity differences and genotype-phenotype interaction should be performed to clarify possible roles of IL-23R in UC.

Emerging leadership lecture: Inflammatory bowel disease in Asia: emergence of a "Western" disease

More than a decade ago, inflammatory bowel disease (IBD) is rare in Asia. Today, the importance of IBD in Asia is exemplified by its rapidly increasing incidence, complicated disease behavior, and substantial morbidity. In the first large-scale population-based epidemiologic study in Asia, the incidence of IBD varied from 0.60 to 3.44 per 100,000. There has been a twofold to threefold increase in the incidence of IBD in several countries in Asia. Ulcerative colitis (UC) is more prevalent than Crohn's disease (CD), although CD incidence is rapidly increasing. A positive family history is much less common than in the West, as are extra-intestinal disease manifestations. Complicated and penetrating CD are common in Asia. These epidemiologic changes may relate to increased contact with the West, westernization of diet, improved hygiene, increasing antibiotics use, or changes in the gut microbiota. Asian patients with CD have altered gut microbiota compared with their healthy counterparts and Caucasian CD subjects. Mucosa-associated microbiota in IBD may differ geographically. In a population-based case-control study, breast-feeding, having pets, and better sanitary conditions were protective of IBD, suggesting that childhood environment plays an important role in modulating disease development. Genetic factors also differ between Asians and Caucasians. Nucleotide oligomerization domain-2 (NOD2) and autophagy variants were not associated with CD, but tumor necrosis factor superfamily gene-15 polymorphisms were strongly associated with CD in East Asians. Research in Asia, an area of rapidly changing IBD epidemiology, may lead to the discovery of critical etiologic factors that lead to the development of IBD.

Smoking behaviour modifies IL23r-associated disease risk in patients with Crohn's disease

BACKGROUND AND AIM

The etiology of Crohn's disease (CD) implicates both genetic and environmental factors. Smoking behavior is one environmental risk factor to play a role in the development of CD. The study aimed to assess the contribution of the interleukin 23 receptor (IL23R) in determining disease susceptibility in two independent cohorts of CD, and to investigate the interactions between IL23R variants, smoking behavior, and CD-associated genes, NOD2 and ATG16L1.

METHODS

Ten IL23R single-nucleotide polymorphisms (SNPs) were genotyped in 675 CD cases, and 1255 controls from Brisbane, Australia (dataset 1). Six of these SNPs were genotyped in 318 CD cases and 533 controls from Canterbury, New Zealand (dataset 2). Case-control analysis of genotype and allele frequencies, and haplotype analysis for all SNPs was conducted.

RESULTS

We demonstrate a strong increased CD risk for smokers in both datasets (odds ratio 3.77, 95% confidence interval 2.88-4.94), and an additive interaction between IL23R SNPs and cigarette smoking. Ileal involvement was a consistent marker of strong SNP-CD association (P ≤ 0.001), while the lowest minor allele frequencies for location were found in those with colonic CD (L2). Three haplotype blocks were identified across the 10 IL23R SNPs conferring different risk of CD. Haplotypes conferred no further risk of CD when compared with single SNP analyses.

CONCLUSION

IL23R gene variants determine CD susceptibility in the Australian and New Zealand population, particularly ileal CD. A strong additive interaction exists between IL23R SNPs and smoking behavior resulting in a dramatic increase in disease risk depending upon specific genetic background.

TNFSF15 is an independent predictor for the development of Crohn's disease-related complications in Koreans

BACKGROUND

Crohn's disease (CD) is a chronic idiopathic inflammatory bowel disease involving the whole gastrointestinal tract. TNFSF15 has been proved as a susceptibility gene for CD, but there are few reports about the association between TNFSF15 single nucleotide polymorphisms (SNPs) and the clinical course of CD.

AIM

To investigate the association between TNFSF15 genotypes and the clinical course of CD in Koreans.

METHODS

A total of 906 CD patients having TNFSF15 genotype data and clinical information were recruited from CD registry database of a tertiary referral center. The association between five TNFSF15 SNPs (rs4574921, rs3810936, rs6478108, rs6478109, and rs7848647) and various clinical parameters including stricture, non-perianal penetrating complications, bowel resection, and reoperation was investigated.

RESULTS

Among the five SNPs, rs6478108 CC genotype was associated with the development of stricture and non-perianal penetrating complications during follow-up (HR for stricture=1.706, 95% confidence interval 1.178-2.471, P=0.005; HR for non-perianal penetrating complications=1.667, 95% confidence interval 1.127-2.466, P=0.010), and rs4574921 CC genotype was associated with the development of perianal fistula (HR=2.386, 95% confidence interval 1.204-4.727, P=0.013) by multivariate analysis. However, there was no significant association of cumulative operation and reoperation rate with 5 SNPs of TNFSF15.

CONCLUSION

In Korean patients with CD, non-risk allele homozygotes of TNFSF15 SNPs rs6478108 and rs4574921 are independent genetic predictive factors for the development of strictures/non-perianal penetrating complications and perianal fistula, respectively.

rs10865331 associated with susceptibility and disease severity of ankylosing spondylitis in a Taiwanese population

Ankylosing spondylitis (AS) is a highly familial rheumatic disorder and is considered as a chronic inflammatory disease. Genetic factors are involved in the pathogenesis of AS. To identify genes which render people susceptible to AS in a Taiwanese population, we selected six single-nucleotide polymorphisms (SNPs) from previous genome-wide association studies (GWASs) which were associated with AS in European descendants and Han Chinese. To assess whether the six SNPs contributed to AS susceptibility and severity in Taiwanese population, 475 AS patients fulfilling the modified New York Criteria and 527 healthy subjects were recruited. We found that rs10865331 was significantly associated with AS susceptibility and with Bath AS Function Index (BASFI). The AA and AG genotypes of rs10865331 were also significantly associated with a higher erythrocyte sedimentation rate. Our findings provided evidence that rs10865331 is associated AS susceptibility and with disease activity (BASFI) in a Taiwanese population.

IL23R and ATG16L1 variants in Moroccan patients with inflammatory bowel disease

BACKGROUND

Inflammatory bowel diseases (IBD) are chronic diseases of the gastrointestinal tract. Although their pathogenesis is unclear, the combination of genetic predisposition and environmental components are believed to be the main cause of these diseases. Recently, many variants in interleukin 23 receptor (IL23R) and autophagy-related 16-like 1 (ATG16L1) genes have been associated with the disease. Our objective was to assess the frequency of ATG16L1 (T300A) and IL23R (L310P) variants in Moroccan IBD (Crohn's disease and Ulcerative Colitis) patients and to evaluate a possible effect of these variants on disease's phenotype and clinical course.

METHODS

96 Moroccan IBD patients and 114 unrelated volunteers were genotyped for ATG16L1 (T300A) and IL23R (L310P) variants by PCR-restriction fragment length polymorphism.

RESULTS

This is the first report on the prevalence of ATG16L1 (T300A) and IL23R (L310P) variants in a Moroccan group. We found that IL23R (L310P) variant conferred a protective effect for crohn's disease (CD) but not ulcerative colitis (UC) patients. The presence of ATG16L1 (T300A) mutated alleles was associated with CD type but not with disease onset. In addition, the carriage of T300A variant alleles conferred a protective effect in UC.

CONCLUSION

Our results showed that the prevalence of ATG16L1 and IL23R variants was not significantly different between patients and controls. However a possible role of ATG16L1 (T300A) on CD phenotype was suggested.

NOD-like receptors in intestinal homeostasis and epithelial tissue repair

The intestinal epithelium constitutes a dynamic physical barrier segregating the luminal content from the underlying mucosal tissue. Following injury, the epithelial integrity is restored by rapid migration of intestinal epithelial cells (IECs) across the denuded area in a process known as wound healing. Hence, through a sequence of events involving restitution, proliferation and differentiation of IECs the gap is resealed and homeostasis reestablished. Relapsing damage followed by healing of the inflamed mucosa is a hallmark of several intestinal disorders including inflammatory bowel diseases (IBD). While several regulatory peptides, growth factors and cytokines stimulate restitution of the epithelial layer after injury, recent evidence in the field underscores the contribution of innate immunity in controlling this process. In particular, nucleotide-binding and oligomerization domain-like receptors (NLRs) play critical roles in sensing the commensal microbiota, maintaining homeostasis, and regulating intestinal inflammation. Here, we review the process of intestinal epithelial tissue repair and we specifically focus on the impact of NLR-mediated signaling mechanisms involved in governing epithelial wound healing during disease.

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.

The dichotomous pattern of IL-12r and IL-23R expression elucidates the role of IL-12 and IL-23 in inflammation

IL-12 and IL-23 cytokines respectively drive Th1 and Th17 type responses. Yet, little is known regarding the biology of these receptors. As the IL-12 and IL-23 receptors share a common subunit, it has been assumed that these receptors are co-expressed. Surprisingly, we find that the expression of each of these receptors is restricted to specific cell types, in both mouse and human. Indeed, although IL-12Rβ2 is expressed by NK cells and a subset of γδ T cells, the expression of IL-23R is restricted to specific T cell subsets, a small number of B cells and innate lymphoid cells. By exploiting an IL-12- and IL-23-dependent mouse model of innate inflammation, we demonstrate an intricate interplay between IL-12Rβ2 NK cells and IL-23R innate lymphoid cells with respectively dominant roles in the regulation of systemic versus local inflammatory responses. Together, these findings support an unforeseen lineage-specific dichotomy in the in vivo role of both the IL-12 and IL-23 pathways in pathological inflammatory states, which may allow more accurate dissection of the roles of these receptors in chronic inflammatory diseases in humans.

Inflammatory bowel disease: Pathogenesis

Inflammatory bowel disease (IBD), including Crohn’s disease and ulcerative colitis, is characterized by chronic relapsing intestinal inflammation. It has been a worldwide health-care problem with a continually increasing incidence. It is thought that IBD results from an aberrant and continuing immune response to the microbes in the gut, catalyzed by the genetic susceptibility of the individual. Although the etiology of IBD remains largely unknown, it involves a complex interaction between the genetic, environmental or microbial factors and the immune responses. Of the four components of IBD pathogenesis, most rapid progress has been made in the genetic study of gut inflammation. The latest internationally collaborative studies have ascertained 163 susceptibility gene loci for IBD. The genes implicated in childhood-onset and adult-onset IBD overlap, suggesting similar genetic predispositions. However, the fact that genetic factors account for only a portion of overall disease variance indicates that microbial and environmental factors may interact with genetic elements in the pathogenesis of IBD. Meanwhile, the adaptive immune response has been classically considered to play a major role in the pathogenesis of IBD, as new studies in immunology and genetics have clarified that the innate immune response maintains the same importance in inducing gut inflammation. Recent progress in understanding IBD pathogenesis sheds lights on relevant disease mechanisms, including the innate and adaptive immunity, and the interactions between genetic factors and microbial and environmental cues. In this review, we provide an update on the major advances that have occurred in above areas.

Genetic variants associated with Crohn's disease

Crohn’s disease is an immune-related disorder characterized by inflammation of the gastrointestinal mucosa, which can occur in any area throughout the digestive tract. This life-long disease commonly presents with abdominal pain, diarrhea, vomiting, and weight loss. While the exact etiology of this disease is largely unknown, it is thought to arise from an interaction between microbial, immunological, and environmental factors in a genetically susceptible host, whereby the immune system attacks the intestine as it cross reacts against gut microbial antigens. The study of genetic variants associated with Crohn’s disease has shed light on our understanding of disease pathophysiology. A large number of genetic variants identified in Crohn’s disease are related to genes targeting microbial recognition and bacterial wall sensing, the most common being NOD2/CARD15 gene. This review will discuss the recent advance in our knowledge of genetic variants of this disease and how they influence the disease course and prognosis.

Associations between genetic variants in the IRGM gene and inflammatory bowel diseases in the Korean population

BACKGROUND

Recent European ancestry genome-wide association studies have identified genetic variants of IRGM as significant susceptibility loci for Crohn's disease (CD). Therefore, we investigated whether genetic variants of IRGM confer genetic susceptibility to CD or ulcerative colitis (UC) and evaluated the genotype-phenotype associations in the Korean population.

METHODS

This study included 510 inflammatory bowel disease (IBD) patients (253 patients with CD and 257 with UC) and 520 healthy controls in Koreans. Initially, we performed direct sequencing analysis to identify unique IRGM single nucleotide polymorphisms (SNPs). Three selected haplotype-tagging SNPs and one risk locus (rs72553867, rs10065172, rs4958847, and rs12654043) within the IRGM were then geno-typed in patients and controls.

RESULTS

IRGM SNP rs10065172 was significantly associated with CD susceptibility in terms of allelic frequency (P = 0.004; odds ratio [OR] = 1.42) and genotype frequency (dominant model, P = 0.008; OR = 1.62). We also found a relationship between SNP rs72553867 and CD susceptibility in the analysis of allelic frequency (P = 0.0117; OR = 0.67) and genotype frequency (dominant model, P = 0.002; OR = 0.55). In addition, we observed that the association of CD with rs10065172 became stronger in patients with younger age at diagnosis (≤ 20 years) or male gender. However, there was no significant association between the four SNPs and UC susceptibility.

CONCLUSIONS

This is the first study to identify SNP rs10065172 and rs72553867 in IRGM as principal CD susceptibility loci in an Asian population.

Genotype/phenotype analyses for 53 Crohn's disease associated genetic polymorphisms

Background & Aims

Recent studies reported a role for more than 70 genes or loci in the susceptibility to Crohn’s disease (CD). However, the impact of these associations in clinical practice remains to be defined. The aim of the study was to analyse the relationship between genotypes and phenotypes for the main 53 CD-associated polymorphisms.

Method

A cohort of 798 CD patients with a median follow up of 7 years was recruited by tertiary adult and paediatric gastroenterological centres. A detailed phenotypic description of the disease was recorded, including clinical presentation, response to treatments and complications. The participants were genotyped for 53 CD-associated variants previously reported in the literature and correlations with clinical sub-phenotypes were searched for. A replication cohort consisting of 722 CD patients was used to further explore the putative associations.

Results

The NOD2 rare variants were associated with an earlier age at diagnosis (p = 0.0001) and an ileal involvement (OR = 2.25[1.49–3.41] and 2.77 [1.71–4.50] for rs2066844 and rs2066847, respectively). Colonic lesions were positively associated with the risk alleles of IL23R rs11209026 (OR = 2.25 [1.13–4.51]) and 6q21 rs7746082 (OR = 1.60 [1.10–2.34] and negatively associated with the risk alleles of IRGM rs13361189 (OR = 0.29 [0.11–0.74]) and DEFB1 rs11362 (OR = 0.50 [0.30–0.80]). The ATG16L1 and IRGM variants were associated with a non-inflammatory behaviour (OR = 1.75 [1.22–2.53] and OR = 1.50 [1.04–2.16] respectively). However, these associations lost significance after multiple testing corrections. The protective effect of the IRGM risk allele on colonic lesions was the only association replicated in the second cohort (p = 0.03).

Conclusions

It is not recommended to genotype the studied polymorphisms in routine practice.

Association of single nucleotide polymorphisms of IL23R and IL17 with ulcerative colitis risk in a Chinese Han population

Background

Previous studies implicated that IL23R and IL17 genes play an important role in autoimmune inflammation. Genome-wide association studies have also identified multiple single nucleotide polymorphisms (SNPs) in the IL23R gene region associated with inflammatory bowel diseases. This study examined the association of IL23R and IL17A gene SNPs with ulcerative colitis susceptibility in a population in China.

Methodology

A total of 270 ulcerative colitis and 268 healthy controls were recruited for the analyses of 23 SNPs in the IL23R and IL17A regions. Genomic DNA was extracted and analysis of these 23 SNPs using ligase detection reaction allelic (LDR) technology. Genotype and allele associations were calculated using SPSS 13.0 software package.

Principal Findings

Compared to the healthy controls, the variant alleles IL23R rs7530511, and rs11805303 showed a statistically significant difference for ulcerative colitis susceptibility (0.7% vs 3.3%, P = 0.002; 60.4% vs 53.2%, P = 0.0017, respectively). The linkage disequilibrium (LD) patterns of these SNPs were measured and three LD blocks from the SNPs of IL23R and one block from those of IL17A were identified. A novel association with ulcerative colitis susceptibility occurred in haplotypes of IL23R (Block1 H3 P = 0.02; Block2 H2 P = 0.019; Block3 H4 P = 0.029) and IL17A (H4 P = 0.034). Pair-wise analyses showed an interaction between the risk haplotypes in IL23R and IL17A (P = 0.014).

Conclusions

Our study demonstrated that rs7530511, and rs11805303 of IL23R were significantly associated with ulcerative colitis susceptibility in the Chinese population. The most noticeable finding was the linkage of IL23R and IL17A gene region to ulcerative colitis risk due to the gene-gene interaction.

The role of prolonged viral gastrointestinal infections in the development of immunodeficiency-related enteropathy

Patients with primary immunodeficiencies are prone to develop enteropathy of unknown pathogenesis. We hypothesize that ineffective clearance of gastrointestinal pathogens, particularly viruses, in combination with defective immune regulation may cause inflammatory enteropathy in certain immunodeficient hosts. We reviewed publications related to prolonged enteric viral infection, immunodeficiency, and the subsequent development of inflammatory enteropathy. Prolonged infection with especially enteroviral infections was reported more often in immunocompromised hosts than in healthy individuals. Protracted enteric viral shedding was not always associated with the presence or duration of gastrointestinal symptoms. The development of immunodeficiency-associated enteropathy after prolonged viral infections was described in sporadic cases. Clinical consequences of viral gut infections in immunocompromised hosts comprise isolation issues and supportive care. Prospective studies in cohorts of immunodeficient patients are required to study the impact of prolonged enteric viral replication with respect to the pathogenesis of non-infectious enteropathy.

Genetics of inflammatory bowel disease in Asia: systematic review and meta-analysis

BACKGROUND

Inflammatory bowel diseases (IBD) result from an interaction between genetic and environmental factors. Preliminary findings suggest that susceptibility genes differ between IBD patients in Asia and the West. We aimed to evaluate disease-predisposing genes in Asian IBD patients.

METHODS

A systematic review and meta-analysis were performed of published studies from 1950 to 2010 using keyword searches in MEDLINE, EMBASE, EBM Reviews, and BIOSIS Previews.

RESULTS

In all, 477 abstracts were identified and data extracted from 93 studies, comprising 17,976 IBD patients and 27,350 age- and sex-matched controls. Major nucleotide oligomerization domain (NOD)-2 variants in Western Crohn's disease (CD) patients were not associated with CD in Han Chinese, Japanese, South Korean, Indian, and Malaysian populations. New NOD2 mutations were, however, associated with CD in Malaysians (JW1), Han Chinese, and Indians (P268S). Autophagy-related protein 16-linked 1 (ATG16L1) was not associated with CD in East Asians (odds ratio [OR] 0.97; 95% confidence interval [CI] 0.84-1.13). Interleukin (IL)-23R was associated with CD in South Koreans (OR 1.8; 95% CI 1.16-2.82) and a single nucleotide polymorphism in IL-23R (Gly149Arg) was protective of CD in Han Chinese (OR 0.3; 95% CI 0.15-0.60). Tumor necrosis factor (TNF) superfamily gene-15 (SF15) polymorphisms were associated with CD (OR 2.68; 95% CI 1.86-3.86), while TNF-308 polymorphisms (OR 1.82; 95% CI 1.15-2.9), cytotoxic T lymphocyte antigen (CTLA)-4 (OR 2.75; 95% CI 1.22-6.22) and MICA allele (OR 2.41; 95% CI 1.89-3.07) were associated with ulcerative colitis in Asians.

CONCLUSIONS

Genetic mutations of IBD in Asians differ from Caucasians. New mutations and susceptibility genes identified in Asian IBD patients provide an opportunity to explore new disease-associated mechanisms in this population of rising incidence.

Association of peroxisome proliferator-activated receptor gamma polymorphisms with inflammatory bowel disease in a Hungarian cohort

BACKGROUND

Inflammatory bowel disease (IBD) shows increasing incidence in the last few years in Eastern Europe, including Hungary. Since genetic susceptibility of patients plays an important role in the development and pathogenesis of IBD, it is important to identify new susceptibility genes. Peroxisome proliferator-activated receptor gamma (PPARγ) is expressed in the colon and has protective effects against inflammatory processes. Our aim was to examine the association of four polymorphisms of PPARγ in a well-characterized Hungarian IBD cohort.

METHODS

In all, 575 Crohn's disease (CD), 103 ulcerative colitis (UC) patients, and 486 sex- and age-matched controls were examined. Four polymorphisms of PPARγ (rs10865710 [C-681G], rs2067819, rs3892175, and rs1801282 [Pro12Ala]) were genotyped by TaqMan genotyping assays.

RESULTS

The Pro12Ala polymorphism showed significant association with CD when the frequencies of the homozygous variants (Pro/Pro vs. Ala/Ala) were compared. The minor Ala/Ala genotype was significantly less frequent in CD patients compared to the controls (odds ratio [OR] = 0.33; 95% confidence interval [CI] = 012-0.94; P = 0.03), suggesting a potential protective effect of the Ala allele. The GAGG haplotype of PPARγ confers a protective effect in CD; however, it is not significant, but in UC it has a protective effect with a significant level (OR = 0.14; 95% CI: 0.05-0.42; P = 3.78 × 10(-5) ), while GAGC increases the risk of UC (OR = 6.70; 95% CI: 3.41-13.17; P = 3.85 × 10(-10) ).

CONCLUSIONS

In the present study we demonstrated a significant association between PPARγ polymorphisms and the development of CD and UC at single loci level and also in haplotype combinations.

Role of ATG16L, NOD2 and IL23R in Crohn’s disease pathogenesis

Inflammatory bowel disease is a group of diseases that includes Crohn’s disease (CD) and ulcerative colitis. CD is characterized as a chronic inflammatory disease of the gastrointestinal tract, ranging from the mouth to the anus. Although there are gross pathological and histological similarities between CD and Johne’s disease of cattle, the cause of CD remains controversial. It is vital to understand fully the cause of this disease because it affects approximately 500 000 people in North America and Europe. It ranges from 27 to 48 cases per 100 000 people. There are many theories on the cause of CD ranging from possible association with environmental factors including microorganisms to imbalance in the intestinal normal flora of the patients. Regardless of the environmental trigger, there is strong evidence that a genetic disposition is a major key in acquiring CD. Many studies have proven the link between mutations in the ATG16L, NOD2/CARD15, IBD5, CTLA4, TNFSF15 and IL23R genes, and CD. The purpose of this review is to examine all genetic aspects and theories of CD, including up to date multiple population studies performed worldwide.

Investigation of JAK2, STAT3 and CCR6 polymorphisms and their gene-gene interactions in inflammatory bowel disease

Genome-wide association studies identified many loci associated with the two forms of inflammatory bowel disease (IBD), Crohn's disease (CD) and ulcerative colitis (UC). Components of the interleukin-23 signalling pathway, such as IL23R, JAK2 and STAT3, have been implicated in both diseases. In addition, emerging evidence supports the role of IL23-driven Th17 cells in inflammation. Here, we studied the susceptibility nature of three components of IL23 signalling and Th17 cell differentiation: JAK2 rs10758669, STAT3 rs744166 and CCR6 rs2301436 initially associated with CD in Hungarian CD and UC patients. A total of 616 unrelated subjects with either form of IBD and 496 healthy controls were genotyped with PCR-RFLP methods. We also tested the genetic interactions of JAK2, STAT3 and CCR6 polymorphisms in a pairwise fashion with regard to disease risk. We could confirm the susceptibility of STAT3 rs744166 TT homozygotes for UC (OR: 1.483, 95% CI: 1.103-1.992, P = 0.009). Data on genetic interaction reveals that the above JAK2 and STAT3 risk alleles contribute to CD susceptibility in combination with each other (OR: 2.218; 95% CI: 1.097-4.487; P = 0.024), while the JAK2 variant shows a tendency to confer UC risk only on a wild-type STAT3 background (OR: 1.997, 95%CI: 0.994-4.009, P = 0.049). Our results may help in understanding how these natural variants contribute to development of IBD through their genetic association.

Meta-analysis of published studies identified eight additional common susceptibility loci for Crohn's disease and ulcerative colitis

BACKGROUND

Both ulcerative colitis (UC) and Crohn's disease (CD) have a complex etiology involving multiple genetic and environmental factors. Many genome-wide association studies (GWAS) and subsequent replication studies revealed that both diseases share some of the susceptibility loci; however, common genetic factors for both diseases are not fully elucidated. This study is aimed to identify the common genetic factors for CD and UC by a meta-analysis of published studies.

METHODS

We first reviewed the 10 GWAS for CD to select candidate single nucleotide polymorphisms (SNPs). Next, we performed a PubMed literature search up to June 30, 2010 and carried out a systemic review of published studies that examined the association of CD susceptibility loci in UC patients. Meta-analysis was carried out using the inverse variance-weighted method or the DerSimonian-Laird method after estimating the heterogeneity among the studies. The data for highly linked SNPs were combined. Finally, we performed a meta-analysis of 43 published studies in 45 SNPs located at 33 loci by using a total of 4852 to 31,125 subjects.

RESULTS

We confirmed the association of 17 reported common susceptibility loci. Moreover, we found associations at eight additional loci: GCKR, ATG16L1, CDKAL1, ZNF365, LRRK2-MUC19, C13orf31, PTPN2, and SBNO2. The genetic risk of each locus was modest (odds ratios ranged from 1.05-1.22) except IL23R.

CONCLUSIONS

These results indicate that CD and UC share many susceptibility loci with small genetic effect. Our data provide further understanding of the common pathogenesis between CD and UC.

Innate and adaptive immunity in inflammatory bowel disease

Inflammatory bowel diseases are the consequence of a dysregulated mucosal immune system. The mucosal immune system consists of two arms, innate and adaptive immunity, that have been studied separately for a long time. Functional studies from in vivo models of intestinal inflammation as well as results from genome-wide association studies strongly suggest a cross-regulation of both arms. The present review will illustrate this interaction by selecting examples from innate immunity and adaptive immunity, and their direct impact on each other. Broadening our view by focusing on the cross-regulated areas of the mucosal immune system will not only facilitate our understanding of disease, but furthermore will allow identification of future therapeutic targets.

Association between IL-23R single nucleotide polymorphisms and inflammatory bowel disease

AIM: To detect the association between single nucleotide polymorphism (SNP) of the interleukin-23 receptor (IL-23R) gene and inflammatory bowel disease (IBD) in Chinese patients.

METHODS: We examined three nonsynonymous SNPs in the IL-23R gene which lead to amino acid changes (rs11209026, p.Arg381Gln; rs41313262, p.Val362Ile; rs11465797, p.Thr175Asn). The SNPs were genotyped by polymerase chain reaction (PCR) and sequenced in 198 cases of IBD [124 cases of ulcerative colitis (UC) and 74 cases of Crohn's disease (CD)] and 100 healthy controls. The allele frequencies were calculated and analyzed to examine the relationship between IL-23R SNPs and IBD.

RESULTS: The frequency of the A allele in the IL-23R Arg381Gln locus showed no significant difference between CD patients and controls (2.70% vs 6.00%, P > 0.05) and between UC patients and controls (5.65% vs 6.00%, P > 0.05). The p.Val362Ile variant was present in 2.42% of UC patients, in 2.70% of CD patients, and in 2.00% of controls, with no significant difference among the three groups. The Thr175Asn (rs11465797 c.524 C>A) variant was not detected in all the three groups.

CONCLUSION: IL-23R SNPs might have no association with IBD in Chinese patients.

Crohn disease: a current perspective on genetics, autophagy and immunity

Crohn disease (CD) is a chronic and debilitating inflammatory condition of the gastrointestinal tract. Prevalence in Western populations is 100-150/100,000 and somewhat higher in Ashkenazi Jews. Peak incidence is in early adult life, although any age can be affected and a majority of affected individuals progress to relapsing and chronic disease. Medical treatments rely significantly on empirical corticosteroid therapy and immunosuppression, and intestinal resectional surgery is frequently required. Thus, 80% of patients with CD come to surgery for refractory disease or complications. It is hoped that an improved understanding of pathogenic mechanisms, for example by studying the genetic basis of CD and other forms of inflammatory bowel diseases (IBD), will lead to improved therapies and possibly preventative strategies in individuals identified as being at risk.

Crohn disease: a current perspective on genetics, autophagy and immunity

Crohn disease (CD) is a chronic and debilitating inflammatory condition of the gastrointestinal tract. Prevalence in Western populations is 100-150/100,000 and somewhat higher in Ashkenazi Jews. Peak incidence is in early adult life, although any age can be affected and a majority of affected individuals progress to relapsing and chronic disease. Medical treatments rely significantly on empirical corticosteroid therapy and immunosuppression, and intestinal resectional surgery is frequently required. Thus, 80% of patients with CD come to surgery for refractory disease or complications. It is hoped that an improved understanding of pathogenic mechanisms, for example by studying the genetic basis of CD and other forms of inflammatory bowel diseases (IBD), will lead to improved therapies and possibly preventative strategies in individuals identified as being at risk.

Common variants in NOD2 and IL23R are not associated with inflammatory bowel disease in Indians

BACKGROUND AND AIM

Ulcerative colitis (UC) and Crohn's disease (CD) are two major phenotypes of inflammatory bowel disease (IBD) that present with inflammation of the colon or the entire gastrointestinal tract, respectively. Genome-wide association studies have confirmed the role of nucleotide-binding oligomerization domain protein-2 (NOD2) variants and identified several other genes associated with IBD. We investigated whether variants in NOD2 and interleukin-23 receptor (IL23R) are associated with IBD in a well-characterized case-control cohort from southern India.

METHODS

We recruited 652 patients (411 UC and 241 CD) using established diagnostic criteria and 442 age-, sex-, and ethnically-matched, normal individuals. By direct sequencing, we screened the complete NOD2 gene and genotyped the R381Q variant in IL23R, and performed an association analysis and genotype-phenotype correlation analysis.

RESULTS

The clinical presentation of UC and CD patients did not differ significantly from the Europeans. We observed a monomorphic status for three common disease-susceptible variants, R702W, G908R, and 1007fs in NOD2; three other single nucleotide polymorphisms, P268S, R459R, and R587R, had a comparable minor allele frequency in patients and controls. Compared to Europeans, we found a low frequency (∼1%) of the protective allele at R381Q in IL23R and no statistically-significant association with IBD (odds ratio = 0.87; 95% confidence interval = 0.26-2.86; P>0.05).

CONCLUSIONS

Our study suggests that variants in the NOD2 gene and the protective variant R381Q in IL23R are not associated with IBD in Indians. Additional variants in these or other candidate genes might play a major role in the pathophysiology of IBD in Indians.

Genetics of ulcerative colitis

Ulcerative colitis (UC) and Crohn's disease (CD) are related polygenic inflammatory bowel diseases (IBDs), with distinct and overlapping susceptibility loci. Recently, hypothesis-free genome-wide association (GWA) studies have revolutionized the field of complex disease genetics. Substantial advances have been achieved in defining the genetic architecture of IBD. To date, over 60 published IBD susceptibility loci have been discovered and replicated, of which approximately a third are associated with both UC and CD, although 21 are specific to UC and 23 to CD. In CD, the breakthrough identification of NOD2 as a susceptibility gene was followed by a rapid phase of gene discovery from GWA studies between 2006 and 2008. Progress in UC was slower; however, by initially testing hits for CD in UC, and later scanning larger UC cohorts, significant new loci for UC have been discovered, with exciting novel insights into disease pathogenesis. Notably, genes implicated in mucosal barrier function (ECM1, CDH1, HNF4α, and laminin B1) confer risk of UC; furthermore, E-cadherin is the first genetic correlation between colorectal cancer and UC. Impaired IL10 signaling has reemerged as a key pathway in intestinal inflammation, and is perhaps the most amenable to therapeutic intervention in UC. Collaborative international efforts with large meta-analyses of GWA studies and replication will yield many new UC genes. Furthermore, a large effort is required to characterize the loci found. Fine-mapping, deep resequencing, and functional studies will be critical to translating these gene discoveries into pathogenic insights, and ultimately into clinical insights and novel therapeutics.

An investigation of genome-wide studies reported susceptibility loci for ulcerative colitis shows limited replication in north Indians

Genome-Wide Association studies (GWAS) of both Crohn's Disease (CD) and Ulcerative Colitis (UC) have unearthed over 40 risk conferring variants. Recently, a meta-analysis on UC revealed several loci, most of which were either previously associated with UC or CD susceptibility in populations of European origin. In this study, we attempted to replicate these findings in an ethnically distinct north Indian UC cohort. 648 UC cases and 850 controls were genotyped using Infinium Human 660W-quad. Out of 59 meta-analysis index SNPs, six were not in the SNP array used in the study. Of the remaining 53 SNPs, four were found monomorphic. Association (p<0.05) at 25 SNPs was observed, of which 15 were CD specific. Only five SNPs namely rs2395185 (HLA-DRA), rs3024505 (IL10), rs6426833 (RNF186), rs3763313 (BTNL2) and rs2066843 (NOD2) retained significance after Bonferroni correction. These results (i) reveal limited replication of Caucasian based meta-analysis results; (ii) reiterate overlapping molecular mechanism(s) in UC and CD; (iii) indicate differences in genetic architecture between populations; and (iv) suggest that resources such as HapMap need to be extended to cover diverse ethnic populations. They also suggest a systematic GWAS in this terrain may be insightful for identifying population specific IBD risk conferring loci and thus enable cross-ethnicity fine mapping of disease loci.