Association of signal transducer and activator of transcription 4 genetic variants with extra-intestinal manifestations in inflammatory bowel disease

STATs, promising targets for the treatment of autoimmune and inflammatory diseases

Cytokines play a crucial role in the pathophysiology of autoimmune and inflammatory diseases, with over 50 cytokines undergoing signal transduction through the Signal Transducers and Activators of Transcription (STAT) signaling pathway. Recent studies have solidly confirmed the pivotal role of STATs in autoimmune and inflammatory diseases. Therefore, this review provides a detailed summary of the immunological functions of STATs, focusing on exploring their mechanisms in various autoimmune and inflammatory diseases. Additionally, with the rapid advancement of structural biology in the field of drug discovery, many STAT inhibitors have been identified using structure-based drug design strategies. In this review, we also examine the structures of STAT proteins and compile the latest research on STAT inhibitors currently being tested in animal models and clinical trials for the treatment of immunological diseases, which emphasizes the feasibility of STATs as promising therapeutic targets and provides insights into the design of the next generation of STAT inhibitors.

SNPs in the interleukin-12 signaling pathway are associated with breast cancer risk in Puerto Rican women

Interleukin-12 (IL-12) is a proinflammatory cytokine that links innate and adaptive immune responses against tumor cells. Single Nucleotide Polymorphisms (SNPs) in IL-12 genes have been associated with cancer risk. However, limited studies have assessed the role of IL-12 in breast cancer (BC) risk comprehensively, and these were done in European and Asian populations. Here, we evaluated the association of the IL-12 signaling pathway and BC risk in Puerto Rican women. A genetic association study was completed with 461 BC cases and 463 non-BC controls. By logistic regression, IL-12 signaling SNPs were associated with an increased BC risk, including rs2243123 (IL12A), rs3761041, rs401502 and rs404733 (IL12RB1), rs7849191 (JAK2), rs280500 (TYK2) and rs4274624 (STAT4). Conversely, other SNPs were associated with reduced BC risk including rs438421 (IL12RB1), rs6693065 (IL12RB2), rs10974947, and rs2274471 (JAK2), rs10168266 and rs925847 (STAT4), and rs2069718 (IFNG). Analyses based in hormone receptors such as estrogen (ER) and progesterone (PR) receptors also revealed protective (for SNPs rs3212227-IL12B; rs3024896 and rs3821236-STAT4) and predisposing (for rs2069705-IFNG SNP) BC associations. Haplotype analysis showed a decreased BC risk for IL12B and STAT4 SNPs, whereas increased risk for IL12RB1 SNPs. This study suggests a role of the IL-12 signaling axis and BC risk. SNPs in this pathway may alter IL-12 induced anti-tumor responses and modulate BC predisposition in a population-specific context. Functional studies will be necessary to confirm these findings, which potentially may benefit IL-12 related immunotherapeutic approaches towards BC.

Pathogenesis and clinical perspectives of extraintestinal manifestations in inflammatory bowel diseases

A considerable number of patients with inflammatory bowel disease (IBD) experience extraintestinal manifestations (EIMs), which can present either before or after IBD diagnosis. Unraveling the pathogenic pathways of EIMs in IBD is challenging because of the lack of reliable criteria for diagnosis and difficulty in distinguishing EIMs from external pathologies caused by drugs or other etiologies. Optimizing treatment can also be difficult. Early diagnosis and management of EIM revolve around multidisciplinary teams, and they should have the resources necessary to make and implement appropriate decisions. In addition, specialists of the affected organs should be trained in IBD treatment. Furthermore, patient awareness regarding the extraintestinal symptoms of IBD is of paramount importance for improving patient understanding of disease and health outcomes. Herein, we review the pathogenesis and clinical perspectives of EIMs in IBD.

Protective effects of guggulsterone against colitis are associated with the suppression of TREM-1 and modulation of macrophages

Triggering receptor expressed on myeloid cells 1 (TREM-1)-expressing intestinal macrophages are significantly increased in the colons of patients with inflammatory bowel disease (IBD). We focused here on the effects of guggulsterone on macrophage modulation in colitis as a potential therapeutic molecule in human IBD and explore the underlying mechanisms. Gene expression in macrophages was examined and wound-healing assay using HT-29 cells was performed. Colitis in wild-type and IL-10-, Toll-like receptor 4 (TLR4)-, and myeloid differentiation primary response 88 (MyD88)-deficient mice was induced via the administration of 2,4,6-trinitrobenzene sulfonic acid (TNBS) into the colon. In both in vitro and in vivo experiments, guggulsterone suppressed intestinal inflammation amplified by TREM-1 stimulation, in which the suppression of NF-κB, activating protein-1, and proteasome pathways was involved. In the TNBS-induced colitis model, guggulsterone reduced disease activity index scores and TREM-1 expression, stimulated IL-10 production, and improved survival in wild-type mice. These effects were not observed in IL-10-, TLR4-, and MyD88-deficient mice. Guggulsterone also suppressed M1 polarization, yet induced the M2 phenotype in macrophages from IBD patients as well as from mice. These findings indicate that guggulsterone blocks the hyperactivation of macrophages via TREM-1 suppression and induces M2 polarization via IL-10 mediated by the TLR4 signaling pathway. Furthermore, this study provides a new rationale for the therapeutic potential of guggulsterone in the treatment of IBD. NEW & NOTEWORTHY We found that guggulsterone attenuates triggering receptor expressed on myeloid cells 1 (TREM-1)-mediated hyperactivation of macrophages and polarizes macrophages toward the M2 phenotype. This was mediated by IL-10 and partly Toll-like receptor 4 signaling pathways. Overall, these data support that guggulsterone as a natural plant sterol modulates macrophage phenotypes in colitis, which may be of novel therapeutic importance in inflammatory bowel disease treatment.

Effector T Helper Cell Subsets in Inflammatory Bowel Diseases

The gastrointestinal tract is a site of high immune challenge, as it must maintain a delicate balance between tolerating luminal contents and generating an immune response toward pathogens. CD4⁺ T cells are key in mediating the host protective and homeostatic responses. Yet, CD4⁺ T cells are also known to be the main drivers of inflammatory bowel disease (IBD) when this balance is perturbed. Many subsets of CD4⁺ T cells have been identified as players in perpetuating chronic intestinal inflammation. Over the last few decades, understanding of how each subset of Th cells plays a role has dramatically increased. Simultaneously, this has allowed development of therapeutic innovation targeting specific molecules rather than broad immunosuppressive agents. Here, we review the emerging evidence of how each subset functions in promoting and sustaining the chronic inflammation that characterizes IBD.

Association of STAT4 rs7574865 polymorphism with susceptibility to inflammatory bowel disease: A systematic review and meta-analysis

OBJECTIVE

Association of Signal transducers and activators of transcription-4 (STAT4) gene polymorphism with susceptibility to inflammatory bowel disease have been investigated in a number of epidemiological studies, but the results are inclusive. The aim of this meta-analysis was to more precisely estimate the relationship.

METHODS

The databases of Pubmed and CBM updated to October, 2014 were retrieved. Random- or fixed-effect model was used to estimate odd radio (OR) and corresponding 95% confidence interval (95%CI) on the basis of heterogeneity.

RESULTS

Seven articles containing 2196 Crohn's disease (CD) cases, 1588 ulcerative colitis (UC) cases and 4126 controls were identified. We detected a significant association between STAT4 rs7574865 polymorphism and IBD susceptibility in overall population (GG vs. GT+TT, OR=0.855, 95% CI=0.760-0.962, P=0.009), but not in Caucasian and Asian population, respectively. No association was detected between rs7574865 polymorphism and CD susceptibility in overall, Asian and Caucasian population, respectively. Interestingly, a significant association was detected between rs7574865 with UC susceptibility in overall population (G vs. T, OR=0.881, 95% CI=0.798-0.972, P=0.012; GG vs. GT+TT, OR=0.788, 95% CI=0.679-0.914, P=0.002; GG vs. TT, OR=0.683, 95% CI=0.498-0.937, P=0.018) and Caucasians (GG vs. GT+TT, OR=0.833, 95% CI=0.701-0.990, P=0.038; GG+GT vs. TT, OR=0.667, 95% CI=0.456-0.975, P=0.037; GG vs. TT, OR=0.636, 95% CI=0.433-0.934, P=0.021), respectively, and a possible association was found in Asian population (GG vs. GT+TT, OR=0.709, 95% CI=0.503-0.998, P=0.049).

CONCLUSIONS

STAT4 rs7574865 gene is IBD risk factor, and this gene polymorphism is associated with UC susceptibility, especially in Caucasians. To confirm these findings, further studies with more sample size are required for a definitive conclusion.

Altered STAT4 Isoform Expression in Patients with Inflammatory Bowel Disease

BACKGROUND

Crohn's disease (CD) and ulcerative colitis (UC) are the major forms of inflammatory bowel disease, and pathogenesis involves a complex interplay among genetic, environmental, and immunological factors. We evaluated isoform expression of the IL-12-activated transcription factor STAT4 in children with CD and UC.

METHODS

We collected biopsy samples from both patients newly diagnosed with CD and with UC. We further collected blood samples from patients newly diagnosed with CD and with UC as well as from patients who had a flare-up after being in clinical remission, and we examined the ratios of STAT4β/STAT4α mRNA. In addition to STAT4 isoforms, we measured the expression of the cytokines TNFα, IFNγ, granulocyte macrophage-colony stimulating factor, and IL-17 using polymerase chain reaction of biopsy samples and multiplex analysis of patient serum samples.

RESULTS

Ratios of STAT4β/STAT4α were increased in specific gastrointestinal tract segments in both patients with CD and those with UC that correlate with the location and severity of inflammation. In contrast, we did not observe changes in STAT4β/STAT4α ratios in biopsy specimens from patients with eosinophilic esophagitis. We also observed increased STAT4β/STAT4α ratios in the peripheral blood mononuclear cells of patients with UC and those with CD, compared with healthy controls. Ratios were normalized after patients were treated with steroids.

CONCLUSIONS

Collectively, these data indicate that STAT4 isoforms could be an important noninvasive biomarker in the diagnosis and treatment of inflammatory bowel disease and that expression of these isoforms might provide further insight into the pathogenesis of IBD.

Inflammatory bowel diseases: Current problems and future tasks

Current knowledge on inflammatory bowel disease (IBD) is mainly endorsed by controlled trials and epidemiologic studies. Yet, we seldom look at the messages from real-world practice. Among a patient population followed since 2008, we looked at an unselected sample of 64 IBD patients [26 Crohn’s disease (CD) and 38 ulcerative colitis (UC)] who had been seen as out-patients in the last year. Inducing remission, mesalamines (86% for UC/69% for CD/33%-16% as MMX formulation) prevailed as prescriptions; steroids (55%/19% for UC/CD) ranked second. Prescription of third-party drugs (antibiotics, NSAIDs, biologics) and adherence, were issues in the maintenance. 34% of CD, and 23% of UC patients showed accompanying immunologic diseases: CD-associated familiar psoriasis (4:9) ranked first. Main Message. The association between IBD (CD mainly) and psoriasis, now found in our practice, matches current basic science gathering IBD together with psoriasis (and perhaps chronic respiratory disease) under the comprehensive term “barrier organ disease” wherein an epithelial surface with sensor systems rules contacts between outer antigens and a reactive underneath tissue, with the balance between inflammation and quiescence kept at any time by mucosal permeability. IBD is thus viewed as a polyfactorial/polygenic/syndromic disorder, embedded into a galaxy of immune conditions offering multiple points of attack. This mindset of splitting the IBDs into pathogenic categories may allow overcoming the uniformly targeting of a single cytokine by biological drugs, in favor of demarcating the boundaries between different disease-subtype-specific indications, and paving the way to future personalized strategies.

Association of STAT4 gene rs7574865G > T polymorphism with ulcerative colitis risk: evidence from 1532 cases and 3786 controls

INTRODUCTION

Several studies have reported the relationship between the STAT4 rs7574865G > T polymorphism as a susceptibility factor to ulcerative colitis (UC). However, the results have been controversial. Therefore, we conducted this meta-analysis to obtain the most reliable estimate of the association.

MATERIAL AND METHODS

PubMed, Embase and Web of Science databases were searched. Crude odds ratios (OR) with 95% confidence intervals (CI) were extracted and pooled to assess the strength of the association between the STAT4 rs7574865G > T polymorphism and risk of UC. A total of five eligible studies including 1532 cases and 3786 controls based on the search criteria were involved in this meta-analysis.

RESULTS

We observed that the STAT4 rs7574865G > T polymorphism was significantly correlated with UC risk when all studies were pooled into the meta-analysis (the allele contrast model: OR = 1.13, 95% CI = 1.02-1.25; the heterozygote codominant model: OR = 1.22, 95% CI = 1.04-1.43; the dominant model: OR = 1.25, 95% CI = 1.07-1.45). In the stratified analysis by ethnicity, significant associations were observed in Spanish for the allele contrast model (OR = 1.20; 95% CI = 1.04-1.39), for the homozygote codominant model (OR = 1.57; 95% CI = 1.07-2.31), for the dominant model (OR = 1.20; 95% CI = 1.01-1.43), and for the recessive model (OR = 1.50; 95% CI = 1.03-2.19).

CONCLUSIONS

This meta-analysis suggests that the STAT4 rs7574865G > T polymorphism is a low-penetrant risk factor for UC, especially in Spanish.

Meta-analysis reveals an association of STAT4 polymorphisms with systemic autoimmune disorders and anti-dsDNA antibody

Signal transducer and activator of transcription 4 (STAT4) has been recently identified as a susceptibility gene for multiple autoimmune diseases. Here we performed a comprehensive analysis of the association between STAT4 and several different autoimmune disorders to identify potential common inflammatory principles behind this association. Our meta-analysis revealed that the STAT4 rs7574865 polymorphism is associated with four autoimmune diseases with systemic pathology, including systemic lupus erythematosus (OR = 1.52; 95% CI = 1.48 - 1.56, P<1.0 × 10(-16)), rheumatoid arthritis (OR = 1.27; 95% CI = 1.21 - 1.33, P < 1.00 × 10(-16)), systemic sclerosis (OR = 1.38; 95% CI = 1.27 - 1.50, P < 1.44 × 10(-14)), and primary Sjogren's syndrome (OR = 1.32; 95% CI = 1.01 - 1.73, P = 4.40 × 10(-2)), while no association was found with type I diabetes, juvenile idiopathic arthritis, ulcerative colitis and Crohn's disease. Furthermore, the stratified meta-analysis also demonstrate that the STAT4 rs7574865 polymorphism is associated with the presence of autoantibodies with systemic reactivity (anti-ds-DNA antibodies) in SLE patients (OR = 1.37; 95% CI = 1.21 - 1.56, P = 1.12 × 10(-6)). However, no such specific association was seen in RA with regard to the presence of non-systemically reacting antibodies, including rheumatoid factor and anti-cyclic citrullinated peptide antibodies. Taken together, these results suggest that STAT4 polymorphisms are associated with autoimmune diseases which are characterized by a systemic pathology and anti-dsDNA antibody.

Genome-wide association study identifies TH1 pathway genes associated with lung function in asthmatic patients

BACKGROUND

Recent meta-analyses of genome-wide association studies in general populations of European descent have identified 28 loci for lung function.

OBJECTIVE

We sought to identify novel lung function loci specifically for asthma and to confirm lung function loci identified in general populations.

METHODS

Genome-wide association studies of lung function (percent predicted FEV1 [ppFEV1], percent predicted forced vital capacity, and FEV1/forced vital capacity ratio) were performed in 4 white populations of European descent (n = 1544), followed by meta-analyses.

RESULTS

Seven of 28 previously identified lung function loci (HHIP, FAM13A, THSD4, GSTCD, NOTCH4-AGER, RARB, and ZNF323) identified in general populations were confirmed at single nucleotide polymorphism (SNP) levels (P < .05). Four of 32 loci (IL12A, IL12RB1, STAT4, and IRF2) associated with ppFEV1 (P < 10(-4)) belong to the TH1 or IL-12 cytokine family pathway. By using a linear additive model, these 4 TH1 pathway SNPs cumulatively explained 2.9% to 7.8% of the variance in ppFEV1 values in 4 populations (P = 3 × 10(-11)). Genetic scores of these 4 SNPs were associated with ppFEV1 values (P = 2 × 10(-7)) and the American Thoracic Society severe asthma classification (P = .005) in the Severe Asthma Research Program population. TH2 pathway genes (IL13, TSLP, IL33, and IL1RL1) conferring asthma susceptibility were not associated with lung function.

CONCLUSION

Genes involved in airway structure/remodeling are associated with lung function in both general populations and asthmatic subjects. TH1 pathway genes involved in anti-virus/bacterial infection and inflammation modify lung function in asthmatic subjects. Genes associated with lung function that might affect asthma severity are distinct from those genes associated with asthma susceptibility.

Genetics of inflammatory bowel diseases: a comparison between Western and Eastern perspectives

Inflammatory bowel disease (IBD) is a chronic relapsing intestinal inflammatory disorder with unidentified causes. Currently, studies indicate that IBD results from a complex interplay between various genetic and environmental factors that produce intestinal inflammation. However, these factors may differ for Asians and Caucasians. Thus, differences in epidemiology, genetic variants, and clinical phenotypes of IBD have been observed between the two populations. Understanding the discrepancies between data from populations with different genetic backgrounds and environmental factors may reveal fundamental aspects of IBD pathogenesis. Accordingly, this review will summarize the current knowledge of IBD genetics studied in Asian countries and compare it with that from Western countries, with special focus on innate bacterial sensing, autophagy, and the interleukin-23 receptor-T helper cell 17 pathway. The epigenetic nature of IBD pathogenesis as well as the pharmacogenetics related to the use of immunomodulators will also be briefly covered.

Polymorphisms of STAT4 and the risk of inflammatory bowel disease: A case-control study in Chinese Han population

Signal transducer and activator of transcription 4 (STAT4) is a transcription factor involved in the signaling pathways of several cytokines, playing an essential role in the development of inflammation in various immune-mediated diseases. Genetic association studies have shown that the STAT4 gene was significantly associated with inflammatory bowel disease (IBD) in Spanish and Caucasian populations. However, these associations in other ethnic populations remain unknown. In the present study, we evaluated the role of the STAT4 rs7574865 and rs7582694 polymorphisms on IBD in 562 unrelated Chinese Han subjects by assessing distributions of genotypes and allele frequencies. Results showed that neither rs7574865 [Crohn's disease (CD): P=0.66, odds ratio (OR) = 0.95, 95% confidence interval (CI) 0.74-1.21; ulcerative colitis (UC): P=0.43, OR=0.85, 95% CI 0.56-1.28; IBD: P=0.52, OR=0.93, 95% CI 0.73-1.17] nor rs7582694 (CD: P=0.40, OR=1.12, 95% CI 0.86-1.44; UC: P=0.50, OR=0.86, 95% CI 0.56-1.33; IBD: P=0.62, OR=1.06, 95% CI 0.83-1.36) was significantly associated with IBD, although the genotype frequency of rs7574865 varied in patients and the controls. In conclusion, our data did not support that STAT4 variants contribute to IBD susceptibility in the Chinese Han population.

Abnormal genetic and epigenetic changes in signal transducer and activator of transcription 4 in the pathogenesis of inflammatory bowel diseases

BACKGROUND AND AIMS

Changes in the expression of signal transducer and activator of transcription 4 (STAT4) contribute to the development of a variety of autoimmune diseases including inflammatory bowel diseases (IBDs). Moreover, epigenetic modifications, including DNA methylation, are considered a basis for differentiation of T helper cells and regulation of cytokines. In this study, we investigated the methylation status of STAT4 gene in IBD patients and the associations between its genetic and epigenetic alterations in IBD patients.

METHODS

Blood and colonic mucosa samples were obtained from Korean patients with IBD and healthy controls. Peripheral blood mononuclear cells (PBMCs) were isolated, and total RNA and genomic DNA were isolated from the PBMCs and colon mucosa tissues. The mRNA level and DNA methylation status of the promoter were determined by real-time RT-PCR and pyrosequencing, respectively. The chosen SNPs (rs11889341, rs7574865, rs8179673, rs6752770, rs925847, rs10168266, rs10181656, and rs11685878) were genotyped using the TaqMan nuclease assay.

RESULTS

Elevated expression of STAT4 was observed in the colonic mucosa and PBMCs of IBD patients. IBD patients showed a lower degree of methylation of the STAT4 promoter than did the healthy controls. Moreover, a significant correlation between risk alleles and methylation status at -172 of the STAT4 promoter was observed, and mRNA levels of STAT4 in IBD patients were correlated inversely with the T-risk allele (rs7574865).

CONCLUSIONS

Our data demonstrated that the DNA methylation status of STAT4 is associated with genetic polymorphisms, providing insights into the interactions between genetic and epigenetic aberrances in STAT4 that contribute to the development of IBD.

Single-nucleotide polymorphisms in inflammatory bowel disease

Strong evidence indicates that inflammatory bowel disease, including Crohn disease and ulcerative colitis, is a result of an inappropriate inflammatory response in which genetic and environmental factors play important roles. This review discusses several single-nucleotide polymorphisms with either susceptibility or protective effects on inflammatory bowel disease.

Interactions between IL17A, IL23R, and STAT4 polymorphisms confer susceptibility to intestinal Behcet's disease in Korean population

AIMS

Although polymorphisms in IL23R have recently been proposed to predispose to Behcet's disease (BD), associations between IL23R polymorphisms and intestinal BD have yet to be elucidated. We therefore performed a study to evaluate whether IL17A, IL23R, and STAT4 polymorphisms are associated with susceptibility to intestinal BD in the Korean population.

MAIN METHODS

Single nucleotide polymorphisms (SNP) in the IL17A, IL23R, and STAT4 genes were analyzed using DNA sequencing, denaturing high performance liquid chromatography, and TaqMan genotyping assays.

KEY FINDINGS

Individual polymorphism analysis revealed that the TT genotype of IL17A rs8193036 (odds ratio (OR) 2.10, 95% confidence interval (CI) (1.12-3.92), p=0.021), and GG+GT genotype of IL23R rs1884444 (OR 1.92, 95% CI (1.03-3.57), p=0.034) was associated with the development of intestinal BD. When these two genotypes were combined, the risk of BD increased compared to that of patients with no-risk or one-risk genotype (OR 2.21, 95% CI (1.13-4.34), p=0.021). Furthermore, statistically significant gene-gene interactions were observed between G149R in IL23R vs. rs11685878 in STAT4, rs2275913 in IL17A vs. rs7574865 in STAT4, and rs11889341 in STAT4 vs. rs2275913 in IL17A. The haplotypes of IL17A had a positive association with intestinal BD risks, whereas those of IL23R were protective for disease development.

SIGNIFICANCE

Our results indicate that the interaction of specific IL17A, IL23R, and STAT4 SNPs modulate susceptibility to intestinal BD in the Korean population, suggesting that the IL-17/23 axis plays a significant role in disease pathogenesis.

Genetics of rheumatoid arthritis: GWAS and beyond

The study of complex genetics in autoimmune diseases has progressed at a tremendous pace over the last 4 years, as a direct result of the enormous gains made by genome wide association studies (GWAS). Novel genetic findings are continuously being reported alongside the rapid development of genetic technologies, sophisticated statistical analysis, and larger sample collections. It is now becoming clear that multiple genes contribute to disease risk in many complex genetic disorders including rheumatoid arthritis (RA) and that there are common genetic risk factors that underlie a spectrum of autoimmune diseases. This review details the current genetic landscape of RA, and describes what GWAS has taught us in terms of missing heritability, subsets of disease, existence of genetic heterogeneity, and shared autoimmune risk loci. Finally, this review addresses the initial challenges faced in translating the wealth of genetic findings into determining the biological mechanisms that contribute to the relationship between genotype and phenotype. Unraveling the mechanism of how genes directly influence the cause of RA will lead to a better understanding of the disease and will ultimately have a direct clinical impact, informing the development of new therapies that can be utilized in the treatment of RA.

Inflammatory bowel disease: beyond the boundaries of the bowel

Dysregulated inflammation in the gut, designated clinically as inflammatory bowel disease (IBD), is manifested by the prototypic phenotypes of an Arthus-like reaction restricted to the mucosa of the colon, as in ulcerative colitis, or a transmural granulomatous reaction, as in Crohn's disease, or an indeterminate form of the two polar types. That the inflammation of IBD can trespass the boundaries of the bowel has long been known, with articular, ophthalmologic, cutaneous, hepatobiliary or other complications/associations - some autoimmune and others not - affecting significant numbers of patients with IBD. Also notable is the frequency of diagnosis of IBD-type diseases on a background of systemic, (mostly myelo-hematological) disorders, associated with alterations of either (or both) innate or adaptive arms of the immune response. Finally, cases of IBD are reported to occur as an adverse effect of TNF inhibitors. Bone marrow transplant has been proven to be the only curative measure for some of the above cases. Thus, in effect, the IBDs should now be regarded as a systemic, rather than bowel-localized, disease. Genome-wide association studies have been informative in consolidating the view of three phenotypes of IBD (ulcerative colitis, Crohn's disease and mixed) and, notably, are revealing that the onset of IBD can be linked to polymorphisms in regulatory miRNAs, or to nucleotide sequences coding for regulatory lymphokines and/or their receptors. At the effector level, we emphasize the major role of the Th17/IL-23 axis in dictating the perpetuation of intestinal inflammation, augmented by a failure of physiological control by regulatory T-cells. In conclusion, there is a central genesis of the defects underlying IBD, which therefore, in our opinion, is best accommodated by the concept of IBD as more of a syndrome than an autonomous disease. This altered mindset should upgrade our knowledge of IBD, influence its medical care and provide a platform for further advances.

Evidence for STAT4 as a common autoimmune gene: rs7574865 is associated with colonic Crohn's disease and early disease onset

Background

Recent studies demonstrated an association of STAT4 variants with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA), indicating that multiple autoimmune diseases share common susceptibility genes. We therefore investigated the influence of STAT4 variants on the susceptibility and phenotype of inflammatory bowel diseases (IBD) in a large patient and control cohort.

Methodology/Principal Findings

Genomic DNA from 2704 individuals of Caucasian origin including 857 patients with Crohn's disease (CD), 464 patients with ulcerative colitis (UC), and 1383 healthy, unrelated controls was analyzed for seven SNPs in the STAT4 gene (rs11889341, rs7574865, rs7568275, rs8179673, rs10181656, rs7582694, rs10174238). In addition, a detailed genotype-phenotype analysis was performed. Our analysis revealed an association of the STAT4 SNP rs7574865 with overall decreased susceptibility to CD (p = 0.047, OR 0.86 [95% CI 0.74–0.99]). However, compared to CD patients carrying the wild type genotype, the STAT4 SNP rs7574865 was significantly associated with early CD onset (p = 0.021) and colonic CD (p = 0.008; OR = 4.60, 95% CI 1.63–12.96). For two other STAT4 variants, there was a trend towards protection against CD susceptibility (rs7568275, p = 0.058, OR 0.86 [95% CI 0.74–1.00]; rs10174238, p = 0.057, OR 0.86 [95% CI 0.75–1.00]). In contrast, we did not observe any association with UC susceptibility. Evidence for weak gene-gene interaction of STAT4 with the IL23R SNP rs11209026 was lost after Bonferroni correction.

Conclusions/Significance

Our results identified the STAT4 SNP rs7574865 as a disease-modifying gene variant in colonic CD. However, in contrast to SLE and RA, the effect of rs7574865 on CD susceptibility is only weak.