Novel genetic risk markers for ulcerative colitis in the IL2/IL21 region are in epistasis with IL23R and suggest a common genetic background for ulcerative colitis and celiac disease

Causal relationships between autoimmune diseases and celiac disease: A Mendelian randomization analysis

The aim of this study was to investigate the causal relationship between autoimmune disorders and celiac disease (CeD) through Mendelian randomization (MR). Single nucleotide polymorphisms (SNPs) significantly associated with 13 autoimmune diseases were extracted from the summary statistics of European genome-wide association studies (GWAS), and their effects were examined by Inverse variance-weighted (IVW) in a large European GWAS on CeD. Finally, reverse MR was performed to investigate the causal effects of CeD on autoimmune traits. Following the application of Bonferroni correction for multiple testing, genetically determined seven autoimmune diseases are causally associated with CeD: Crohn's disease (CD) (OR [95%CI] = 1.156 [1.106 ± 1.208], P = 1.27E-10), primary biliary cholangitis (PBC) (1.229 [1.143 ± 1.321], P = 2.53E-08), primary sclerosing cholangitis (PSC) (1.688 [1.466 ± 1.944], P = 3.56E-13), rheumatoid arthritis (RA) (1.231 [1.154 ± 1.313], P = 2.74E-10), systemic lupus erythematosus (SLE) (1.127 [1.081 ± 1.176], P = 2.59E-08), type 1 diabetes (T1D) (1.41 [1.238 ± 1.606], P = 2.24E-07), and asthma (1.414 [1.137 ± 1.758], P = 1.86E-03). The IVW analysis indicated that CeD increased the risk for seven diseases: CD (1.078 [1.044 ± 1.113], P = 3.71E-06), Graves' disease (GD) (1.251 [1.127 ± 1.387], P = 2.34E-05), PSC (1.304 [1.227 ± 1.386], P = 8.56E-18), psoriasis (PsO) (1.12 [1.062 ± 1.182], P = 3.38E-05), SLE (1.301[1.22 ± 1.388], P = 1.25E-15), T1D (1.3[1.228 ± 1.376], P = 1.57E-19), and asthma (1.045 [1.024 ± 1.067], P = 1.82E-05). The sensitivity analyses deemed the results reliable without pleiotropy. There are positive genetic correlations between various autoimmune diseases and CeD, and the latter also affects the predisposition to multiple autoimmune disorders in the European population.

Correlation analysis of serum levels of H19 and CRP levels and ulcerative colitis

Background

To elucidate clinical applications of detecting serum levels of H19 and CRP in predicting the severity of ulcerative colitis (UC).

Methods

Two hundred UC patients were recruited, and classified to mild/moderate group and severe group according to the Truelove-Witts grading system. Serum levels of H19 and CRP in UC patients were detected by turbidimetric inhibition immuno assay and qRT-PCR. Differences in serum levels of H19 and CRP between mild/moderate group and severe group were analyzed. By plotting ROC curves, the diagnostic potentials of H19 and CRP in UC were evaluated. Kappa conformance test was conducted to validate the conformance of detecting serum levels of H19 and CRP to clinical diagnosis of UC.

Results

Serum levels of H19 and CRP were higher in UC patients of severe group than those of mild/moderate group. Their levels were both positively correlated to the severity of UC. High sensitivity (83.3%) and specificity (80.0%), as well as the maximum Youden index (0.633) were obtained at the cut-off value for H19 level of 2.755, and AUC was 0.8835. Meanwhile, Kappa coefficient (k) was 0.760 at the cut-off value for H19 level of 2.755, showing a high conformance to clinical diagnosis of UC. In addition, acceptable sensitivity (68.49%) and high specificity (85.83%), as well as the maximum Youden index (0.543) were obtained at the cut-off value for CRP level of 6.390 mg/L, and AUC was 0.8018. k was 0.435, showing an acceptable conformance to clinical diagnosis of UC based on serum level of CRP.

Conclusions

Serum levels of H19 and CRP increase with the deterioration of UC. Detecting their serum levels has a consistent result to clinical diagnosis of UC, with a superior performance of H19 than that of CRP.

Heat Shock Transcription Factor 2 Is Significantly Involved in Neurodegenerative Diseases, Inflammatory Bowel Disease, Cancer, Male Infertility, and Fetal Alcohol Spectrum Disorder: The Novel Mechanisms of Several Severe Diseases

HSF (heat shock transcription factor or heat shock factor) was discovered as a transcription factor indispensable for heat shock response. Although four classical HSFs were discovered in mammals and two major HSFs, HSF1 and HSF2, were cloned in the same year of 1991, only HSF1 was intensively studied because HSF1 can give rise to heat shock response through the induction of various HSPs' expression. On the other hand, HSF2 was not well studied for some time, which was probably due to an underestimate of HSF2 itself. Since the beginning of the 21st century, HSF2 research has progressed and many biologically significant functions of HSF2 have been revealed. For example, the roles of HSF2 in nervous system protection, inflammation, maintenance of mitosis and meiosis, and cancer cell survival and death have been gradually unveiled. However, we feel that the fact HSF2 has a relationship with various factors is not yet widely recognized; therefore, the biological significance of HSF2 has been underestimated. We strongly hope to widely communicate the significance of HSF2 to researchers and readers in broad research fields through this review. In addition, we also hope that many readers will have great interest in the molecular mechanism in which HSF2 acts as an active transcription factor and gene bookmarking mechanism of HSF2 during cell cycle progression, as is summarized in this review.

Bidirectional causal link between inflammatory bowel disease and celiac disease: A two-sample mendelian randomization analysis

Background: Observational research has shown a correlation between inflammatory bowel disease (IBD) [comprising ulcerative colitis (UC) and Crohn’s disease (CD)] and celiac disease. However, the relationship between these two diseases remains uncertain.

Methods: We utilized two-sample Mendelian randomization (MR) to estimate the bidirectional causal relationships between IBD and celiac disease. This study utilized data on single nucleotide polymorphisms (SNPs) from genome-wide association studies (GWASs). Heterogeneity, pleiotropy, and sensitivity analyses were also performed to evaluate the MR results.

Results: There was a significant causal relationship between IBD and CD and celiac disease (e.g., IBD and celiac disease, inverse variance weighting (IVW) odds ratio (OR) = 1.0828, 95% CI = 1.0258–1.1428, p = 0.0039; CD and celiac disease, IVW OR = 1.0807, 95% CI = 1.0227–1.1420, p = 0.0058). However, in the reverse direction, we found only suggestive positive causality between celiac disease and CD (e.g., IVW OR = 1.0366, 95% CI = 1.0031–1.0711, p = 0.0319). No evidence of heterogeneity between genetic variants was found (e.g., IBD vs. celiac disease, MR-Egger Q = 47.4391, p = 0.6159). Horizontal pleiotropy hardly influenced causality (e.g., IBD vs. celiac disease, MR-Egger test: p = 0.4340). Leave-one-out analysis showed that individual SNPs did not influence the general results.

Conclusion: Our MR analysis revealed a positive causal link between IBD and celiac disease in the European population. In addition, several recommendations for disease prevention and clinical management have been discussed.

Interpretable network-guided epistasis detection

Background

Detecting epistatic interactions at the gene level is essential to understanding the biological mechanisms of complex diseases. Unfortunately, genome-wide interaction association studies involve many statistical challenges that make such detection hard. We propose a multi-step protocol for epistasis detection along the edges of a gene-gene co-function network. Such an approach reduces the number of tests performed and provides interpretable interactions while keeping type I error controlled. Yet, mapping gene interactions into testable single-nucleotide polymorphism (SNP)-interaction hypotheses, as well as computing gene pair association scores from SNP pair ones, is not trivial.

Results

Here we compare 3 SNP-gene mappings (positional overlap, expression quantitative trait loci, and proximity in 3D structure) and use the adaptive truncated product method to compute gene pair scores. This method is non-parametric, does not require a known null distribution, and is fast to compute. We apply multiple variants of this protocol to a genome-wide association study dataset on inflammatory bowel disease. Different configurations produced different results, highlighting that various mechanisms are implicated in inflammatory bowel disease, while at the same time, results overlapped with known disease characteristics. Importantly, the proposed pipeline also differs from a conventional approach where no network is used, showing the potential for additional discoveries when prior biological knowledge is incorporated into epistasis detection.

Autoimmune susceptibility gene PTPN2 is required for clearance of adherent-invasive Escherichia coli by integrating bacterial uptake and lysosomal defence

OBJECTIVES

Alterations in the intestinal microbiota are linked with a wide range of autoimmune and inflammatory conditions, including inflammatory bowel diseases (IBD), where pathobionts penetrate the intestinal barrier and promote inflammatory reactions. In patients with IBD, the ability of intestinal macrophages to efficiently clear invading pathogens is compromised resulting in increased bacterial translocation and excessive immune reactions. Here, we investigated how an IBD-associated loss-of-function variant in the protein tyrosine phosphatase non-receptor type 2 (PTPN2) gene, or loss of PTPN2 expression affected the ability of macrophages to respond to invading bacteria.

DESIGN

IBD patient-derived macrophages with wild-type (WT) PTPN2 or carrying the IBD-associated PTPN2 SNP, peritoneal macrophages from WT and constitutive PTPN2-knockout mice, as well as mice specifically lacking PTPN2 in macrophages were infected with non-invasive K12 Escherichia coli, the human adherent-invasive E. coli (AIEC) LF82, or a novel mouse AIEC (mAIEC) strain.

RESULTS

Loss of PTPN2 severely compromises the ability of macrophages to clear invading bacteria. Specifically, loss of functional PTPN2 promoted pathobiont invasion/uptake into macrophages and intracellular survival/proliferation by three distinct mechanisms: Increased bacterial uptake was mediated by enhanced expression of carcinoembryonic antigen cellular adhesion molecule (CEACAM)1 and CEACAM6 in PTPN2-deficient cells, while reduced bacterial clearance resulted from defects in autophagy coupled with compromised lysosomal acidification. In vivo, mice lacking PTPN2 in macrophages were more susceptible to mAIEC infection and mAIEC-induced disease.

CONCLUSIONS

Our findings reveal a tripartite regulatory mechanism by which PTPN2 preserves macrophage antibacterial function, thus crucially contributing to host defence against invading bacteria.

A Common Variant at 11q23.3 Is Associated with Susceptibility to Atopic Dermatitis in the Han Chinese Population

Background: Genome-wide association studies (GWASs) have identified many genetic variants that are risk factors for numerous immune-mediated diseases. In particular, different immune-mediated diseases have been found to share the same susceptibility loci. Therefore, exploring the genetic overlap between atopic dermatitis (AD) and other immune-mediated diseases in more detail may help identify additional shared susceptibility loci among common immune-mediated diseases. Recent evidence suggests that the 11q23.3 locus is a susceptibility locus shared among multiple immune-mediated diseases. Objective: This study was designed to investigated whether SNPs at the chromosome 11q23.3 locus are associated with AD in the Han Chinese population. Methods: In total, 16 SNPs within the 11q23.3 locus were genotyped using TaqMan assays for 1,012 AD cases and 1,362 controls. From these SNPs, we selected rs638893 with an association values of p < 5 × 10^-2 for AD for further analysis in an independent replication study using the Sequenom MassARRAY system to genotype an additional (consisting of 1,288 cases and 1,380 controls). The combined analyses were performed in two stages using a meta-analytical method. Results: We identified a common variant at 11q23.3 (rs638893), that was significantly associated (p = 1.58 × 10^-3, OR = 1.22) with AD. The genotype-based association analysis revealed that the recessive model provided the best fit for rs638893. Conclusion: Our study identified a variant on chromosome 11q23.3 that likely confers susceptibility to AD, thereby advancing our understanding of the genetic basis of this disease.

Association Between Inflammatory Bowel Diseases and Celiac Disease: A Systematic Review and Meta-Analysis

BACKGROUND & AIMS

There is controversy over the association between celiac disease (CeD) and inflammatory bowel diseases (IBD). We performed a systematic review and meta-analysis to assess evidence for an association between CeD and IBD.

METHODS

We searched databases including MEDLINE, EMBASE, CENTRAL, Web of Science, CINAHL, DARE, and SIGLE through June 25, 2019 for studies assessing the risk of CeD in patients with IBD, and IBD in patients with CeD, compared with controls of any type. We used the Newcastle-Ottawa Scale to evaluate the risk of bias and GRADE to assess the certainty of the evidence.

RESULTS

We identified 9791 studies and included 65 studies in our analysis. Moderate certainty evidence found an increased risk of CeD in patients with IBD vs controls (risk ratio [RR] 3.96; 95% confidence interval [CI] 2.23-7.02) and increased risk of IBD in patients with CeD vs controls (RR 9.88; 95% CI 4.03-24.21). There was low-certainty evidence for the risk of anti-Saccharomyces antibodies, a serologic marker of IBD, in patients with CeD vs controls (RR 6.22; 95% CI 2.44-15.84). There was low-certainty evidence for no difference in risk of HLA-DQ2 or DQ8 in patients with IBD vs controls (RR 1.04; 95% CI 0.42-2.56), and very low-certainty evidence for an increased risk of anti-tissue transglutaminase in patients with IBD vs controls (RR 1.52; 95% CI 0.52-4.40). Patients with IBD had a slight decrease in risk of anti-endomysial antibodies vs controls (RR 0.70; 95% CI 0.18-2.74), but these results are uncertain.

CONCLUSIONS

In a systematic review and meta-analysis, we found an increased risk of IBD in patients with CeD and increased risk of CeD in patients with IBD, compared with other patient populations. High-quality prospective cohort studies are needed to assess the risk of CeD-specific and IBD-specific biomarkers in patients with IBD and CeD.

Prevalence of Celiac Disease in Children and Adolescents With Inflammatory Bowel Disease

Introduction

The association between inflammatory bowel disease (IBD) - particularly its two main subtypes, ulcerative colitis (UC) and Crohn’s disease (CD) - and celiac disease (CeD) has been attributed to an overlap in the mechanism of immune dysregulation that characterizes these conditions. Owing to the paucity of studies that have explored this condition in pediatric patients, we examined the prevalence of CeD in children with IBD.

Materials and methods

This is a cross-sectional study of children aged two to 18 years with IBD that were diagnosed between 2016 and 2018. Clinical, demographic, laboratory, and endoscopic data were analysed. Serology for CeD measured the immunoglobulin A tissue transglutaminase (IgA-tTG) antibodies, and the diagnosis was confirmed histologically through small bowel biopsies.

Results

The study included 101 patients with IBD (83.2% with UC and 16.8% with CD). The mean age was 8.7±4.0 years. Males constituted 59.4% of the cohort, and only 3% had perianal disease. Ileocolonic involvement was reported in 64.7% and non-stricturing and non-penetrating behaviour in 76.7% of CD patients. Pancolitis constituted 45.2% of UC patients. Ten patients (9.9%) had positive serology based on IgA-tTG antibodies, three (approximately 3%) had CeD based on biopsy findings, two patients (2%) had CD, and one patient (1%) had UC. Patients with confirmed CeD had a significantly higher frequency of symptoms of gaseous sensation and bloating (P=0.003) and abdominal distension (P=0.04).

Conclusions

The prevalence of CeD in Egyptian children with IBD is higher than previously reported in a number of similar studies. Abdominal bloating and gaseous sensation were identified as associated symptoms.

KIAA1109 gene mutation in surviving patients with Alkuraya-Kučinskas syndrome: a review of literature

Background

Alkuraya-Kučinskas syndrome is an autosomal recessive disorder characterized by brain abnormalities associated with cerebral parenchymal underdevelopment, arthrogryposis, club foot and global developmental delay. KIAA1109, a functionally uncharacterized gene is identified as the molecular cause for Alkuraya-Kučinskas syndrome. Most of the reported mutations in KIAA1109 gene result in premature termination of pregnancies or neonatal deaths while a few mutations have been reported in surviving patients with global developmental delay and intellectual disability. To our knowledge, only three surviving patients from two families have been reported with missense variants in KIAA1109. In this study, we describe four surviving patients from two related families (a multiplex family) with global developmental delay and mild to severe intellectual disability with no other systemic manifestations. There were no miscarriages or neonatal deaths reported in these families.

Methods

X-chromosome exome panel sequencing was carried out in one patient and whole exome sequencing was carried out on the remaining three affected individuals and the unaffected father of the index family. Data analysis was carried out followed by variant filtering and segregation analysis. Sanger sequencing was carried out to validate the segregation of mutation in all four affected siblings and unaffected parents from both families.

Results

A novel homozygous missense mutation in a conserved region of KIAA1109 protein was identified. Sanger sequencing confirmed the segregation of mutation in both families in an autosomal recessive fashion.

Conclusion

Our study is the second study reporting a KIAA1109 variant in surviving patients with Alkuraya-Kučinskas syndrome. Our study expands the spectrum of phenotypic features and mutations associated with Alkuraya-Kučinskas syndrome.

Endosomal trafficking defects in patient cells with KIAA1109 biallelic variants

The uncharacterized gene KIAA1 109 has recently been associated with a congenital neurological malformation disorder that variably presents with arthrogryposis, craniofacial and/or cardiac abnormalities. We have identified two additional patients with compound heterozygous KIAA1109 variants presenting with the same neurological malformations. The mechanism whereby KIAA1109 loss of function causes this spectrum of disorders was the primary focus of our studies. We hypothesized that KIAA1109 function could be conserved relative to the fly gene tweek and examined endocytosis and endosome recycling in patient fibroblasts. Furthermore, we examined the structure of the cytoskeleton and cilia based on functional overlap with endocytosis and several known etiologies for neuronal migration disorders. Utilizing primary dermal fibroblasts from one patient and a healthy donor, we performed immunofluorescence and endocytosis assays to examine the endosomal, cytoskeletal, and ciliary cellular phenotypes. We found notable abnormalities in endosomal trafficking and endosome recycling pathways. We also observed changes in the actin cytoskeleton and cilia structural dynamics. We conclude that the function of KIAA1109 in humans may indeed overlap with the function of the Drosophila ortholog, resulting in perturbations to endosomal trafficking and the actin cytoskeleton. These alterations have ripple effects, altering many pathways that are critical for proper neuronal migration and embryonic development.

Phenotype and Clinical Course of Inflammatory Bowel Disease With Co-existent Celiac Disease

BACKGROUND AND AIMS

Inflammatory bowel diseases, principally Crohn's disease and ulcerative colitis, and celiac disease are among the most common immune-mediated gastrointestinal diseases. We aim to elucidate the clinical course and outcomes of patients with concomitant inflammatory bowel disease and celiac disease, a unique population that remains scarcely studied to date.

METHODS

A retrospective matched case-control study of adults with co-existent inflammatory bowel disease [IBD] and celiac disease was performed at a tertiary referral institution in North America. Logistic regression and Kaplan-Meier curves compared disease characteristics and clinical outcomes of the two groups.

RESULTS

A total of 342 inflammatory bowel disease patients were included in this study, of whom 114 had co-existent celiac disease and 228 did not. Patients with co-existent inflammatory bowel disease and celiac disease had higher rates of primary sclerosing cholangitis [19.3% vs 5.7%; odds ratio, 4.4; 95% confidence interval, 2.1-9.4; p <0.001], extensive ulcerative colitis [78.1% vs 59.0%; odds ratio, 2.8; 95% confidence interval, 1.5-5.5; p =0.002], and family history of celiac disease [10.5% vs 3.5%; odds ratio 3.2; 95% confidence interval, 1.3-8.2; p =0.01], compared with patients without concomitant celiac disease.

CONCLUSIONS

Patients with inflammatory bowel disease with concomitant celiac disease have unique phenotypic features compared with non-celiac inflammatory bowel disease, with higher risks for colitis-related hospitalisations, extensive colitis, and primary sclerosing cholangitis. Increased recognition of co-existent IBD and celiac disease can prompt clinicians to investigate for concomitant disease sooner, particularly in patients with seemingly refractory disease.

The Correlation of Serum IL-12B Expression With Disease Activity in Patients With Inflammatory Bowel Disease

Genetic variants in IL12B, encoding the p40 subunit common in interleukin-12 (IL-12) and interleukin-23, were identified as the susceptibility loci for inflammatory bowel disease (IBD). This study aimed to identify the correlation of serum IL-12B expression with disease activity in patients with IBD and evaluate the possibility of IL-12B as a biomarker for assessing inflammatory status in IBD.A total of 102 patients with IBD, including 38, 32, and 32 patients with Crohn's disease (CD), ulcerative colitis (UC), and intestinal Behçet's disease (intestinal BD), respectively, were included. The clinical and laboratory data from the patients were collected at the time of serum IL-12B measurement. Serum IL-12B levels were measured using an enzyme-linked immunosorbent assay.The median IL-12B levels in patients with CD, UC, and intestinal BD were significantly higher than those in controls (1.87, 2.74, and 2.73 pg/mL, respectively, vs. 1.42 pg/mL, all P <0.05). IL-12B concentrations were associated with disease activity in patients with UC and intestinal BD but not in those with CD. IL-12B levels were increased with increasing disease activity in patients with UC (P <0.001). Likewise, patients with active intestinal BD had higher IL-12B levels than those without active disease (P = 0.008). IL-12B levels were correlated with the endoscopic disease activity of UC (P = 0.002) and intestinal BD (P = 0.001) but not that of CD.Serum IL-12B levels were significantly correlated with clinical and endoscopic disease activity in patients with UC and intestinal BD, suggesting its potential use as a biomarker for assessing disease activity in these patients.

Lipocalin-2 Is a Disease Activity Marker in Inflammatory Bowel Disease Regulated by IL-17A, IL-22, and TNF-α and Modulated by IL23R Genotype Status

BACKGROUND

Lipocalin-2 (LCN2) is a potent bacteriostatic protein. We aimed to investigate its role as a disease activity marker in patients with inflammatory bowel disease (IBD) and its induction by the Th17 cytokines IL-17A, IL-22, and TNF-α in colonic epithelial cells. Moreover, we analyzed the influence of IBD-associated IL23R alleles on LCN2 serum levels in IBD patients.

METHODS

LCN2 serum levels were determined in 131 IBD patients (71 with Crohn's disease [CD], 60 with ulcerative colitis [UC]) and 63 healthy controls. IBD patients were genotyped for 10 IBD-associated IL23R polymorphisms. LCN2 expression after stimulation with IL-17A, IL-22, and TNF-α was measured in human colonic epithelial cell lines.

RESULTS

A significant upregulation of serum LCN2 in active IBD (median [IQR], 36.84 [21.17-73.74] ng/mL; P = 0.01) compared with healthy controls (24.22 [17.76-35.25] ng/mL) was confined to active UC (42.21 [28.97-73.74] ng/mL; P = 0.0006). LCN2 proved to be a marker of UC disease activity (area under the curve 0.75, sensitivity 0.83, specificity 0.63; P = 0.0002). IL-17A showed a synergistic effect with IL-22 and TNF-α in inducing colonic epithelial expression of LCN2 and its essential transcription factor IKBZ. In CD, LCN2 concentrations were significantly modulated by IL23R genotype status with homozygous carriers of IBD risk-increasing alleles showing particularly low LCN2 levels.

CONCLUSIONS

Serum LCN2 proves to be a biomarker of active UC. Lower LCN2 levels in CD patients carrying IBD risk-increasing IL23R variants may result from a restricted upregulation of LCN2 due to an impaired Th17 immune response.

Targeting the binding interface on a shared receptor subunit of a cytokine family enables the inhibition of multiple member cytokines with selectable target spectrum

The common γ molecule (γc) is a shared signaling receptor subunit used by six γc-cytokines. These cytokines play crucial roles in the differentiation of the mature immune system and are involved in many human diseases. Moreover, recent studies suggest that multiple γc-cytokines are pathogenically involved in a single disease, thus making the shared γc-molecule a logical target for therapeutic intervention. However, the current therapeutic strategies seem to lack options to treat such cases, partly because of the lack of appropriate neutralizing antibodies recognizing the γc and, more importantly, because of the inherent and practical limitations in the use of monoclonal antibodies. By targeting the binding interface of the γc and cytokines, we successfully designed peptides that not only inhibit multiple γc-cytokines but with a selectable target spectrum. Notably, the lead peptide inhibited three γc-cytokines without affecting the other three or non-γc-cytokines. Biological and mutational analyses of our peptide provide new insights to our current understanding on the structural aspect of the binding of γc-cytokines the γc-molecule. Furthermore, we provide evidence that our peptide, when conjugated to polyethylene glycol to gain stability in vivo, efficiently blocks the action of one of the target cytokines in animal models. Collectively, our technology can be expanded to target various combinations of γc-cytokines and thereby will provide a novel strategy to the current anti-cytokine therapies against immune, inflammatory, and malignant diseases.

Intestinal neuroendocrine cells and goblet cells are mediators of IL-17A-amplified epithelial IL-17C production in human inflammatory bowel disease

Interleukin (IL)-17C is a novel member of the IL-17 cytokine family. Its function in human inflammatory bowel disease (IBD) remains elusive as its role in colonic inflammation is entirely derived from murine models. We aimed to analyze the role of IL-17C in human IBD, focusing on T helper type 17 (Th17) cell- and intestinal epithelial cell (IEC)-dependent mechanisms. IL-17C mRNA (P=0.005), serum levels (P=0.008), and colonic staining intensity (P=0.004) is increased in active IBD. Serum IL-17C levels are modified by IL23R genotypes and IL-17C mRNA correlates (r>0.5, P<0.001) with IL-17A, tumor necrosis factor (TNF)-α, C-C motif chemokine ligand 20 (CCL20) and IL-23 mRNA in the inflamed colon of IBD patients. In the inflamed colon, IL-17C is produced by enteroendocrine and goblet cells, with contrary polar cytosolic localization of IL-17C within the cellular axis. In these two cell types, IL-17A strongly amplifies TNF-α-induced IL-17C production. On the molecular level, IL-17C production in IECs is dependent on TNF-α-activated nuclear factor-κB, extracellular signal-regulated kinase-1/2 and p38, and IL-17A-activated Akt, monocyte chemotactic protein-induced protein 1, and C/EBPδ. IL-17C upregulates the Th17 chemoattractant CCL20 in IECs. In summary, our findings support the involvement of IL-17A-amplified IL-17C production by enteroendocrine and goblet cells in the pathogenesis of active IBD, revealing an interaction between the neuroendocrine system and the Th17 pathway in human IBD.

Co-occurrence of celiac disease and ulcerative colitis in a 12-year-old girl

Celiac disease (CD) and inflammatory bowel diseases (IBD) are separately well-described entities, but the co-occurrence in children has been very rarely reported until today. According to the literature, this case about 12-year-old girl would be the fifth case ever published about co-occurrence in children. We presume that there should be a higher comorbidity prevalence than that described. Distinguishing both diseases in one patient could be difficult due to the overlapping symptoms, but it is very important considering completely different therapeutic approaches.

The NOD2 p.Leu1007fsX1008 mutation (rs2066847) is a stronger predictor of the clinical course of Crohn's disease than the FOXO3A intron variant rs12212067

Background

Very recently, a sub-analysis of genome-wide association scans revealed that the non-coding single nucleotide polymorphism (SNP) rs12212067 in the FOXO3A gene is associated with a milder course of Crohn's disease (CD) (Cell 2013;155:57–69). The aim of our study was to evaluate the clinical value of the SNP rs12212067 in predicting the severity of CD by correlating CD patient genotype status with the most relevant complications of CD such as stenoses, fistulas, and CD-related surgery.

Methodology/Principal Findings

We genotyped 550 CD patients for rs12212067 (FOXO3A) and the three common CD-associated NOD2 mutations rs2066844, rs2066847, and rs2066847 and performed genotype-phenotype analyses.

Results

No significant phenotypic differences were found between the wild-type genotype TT of the FOXO3A SNP rs12212067 and the minor genotypes TG and GG independently from NOD2 variants. The allele frequency of the minor G allele was 12.7%. Age at diagnosis, disease duration, body mass index, surgery rate, stenoses, fistula, need for immunosuppressive therapy, and disease course were not significantly different. In contrast, the NOD2 mutant p.Leu1007fsX1008 (rs2066847) was highly associated with penetrating CD (p = 0.01), the development of fistulas (p = 0.01) and stenoses (p = 0.01), and ileal disease localization (p = 0.03). Importantly, the NOD2 SNP rs2066847 was a strong separator between an aggressive and a mild course of CD (p = 2.99×10⁻⁵), while the FOXO3A SNP rs12212067 did not separate between mild and aggressive CD behavior in our cohort (p = 0.35). 96.2% of the homozygous NOD2 p.Leu1007fsX1008 carriers had an aggressive disease behavior compared to 69.3% of the patients with the NOD2 wild-type genotype (p = 0.007).

Conclusion/Significance

In clinical practice, the NOD2 variant p.Leu1007fsX1008 (rs2066847), in particular in homozygous form, is a much stronger marker for a severe clinical phenotype than the FOXO3A rs12212067 SNP for a mild disease course on an individual patient level despite its important impact on the inflammatory response of monocytes.

Expression of IL-2, IL-17 and TNF-alpha in patients with Crohn's disease treated with anti-TNF antibodies

BACKGROUND

The T cell cytokine IL-17 and the Th-17 pathway appear to have a role in the pathogenesis of inflammatory bowel diseases. IL-2 is a potent stimulator of lymphocyte proliferation and IL2/IL21 receptor polymorphisms have recently been associated with susceptibility to IBD.

AIMS

To evaluate the expression of IL-17, IL-2 and TNFα in Crohn's disease (CD) patients with and without anti-TNFs.

METHODS

Cytokine expression was evaluated by ELISA and intracellular staining of CD4(+) T-cells from the peripheral blood and lamina propria of CD patients and of non-IBD controls. The results were stratified by disease activity and anti-TNF treatment.

RESULTS

IL2 expression was significantly elevated in CD patients not treated with anti-TNFs in comparison to healthy controls (19.6% vs. 33.3%, P=0.03) and CD patients treated with anti-TNFs (20.4% vs. 33.3%, P=0.02), and similar in infliximab-treated patients and controls. IL17 expression was similar in CD patients and controls, and was not affected by anti-TNF therapy. TNFα expression in patients with active CD was increased compared to controls (35.5% vs 25.7%, P<0.005), and was significantly decreased in anti-TNF treated patients in comparison to CD patients without anti-TNFs (39.6% vs 26.2%, P=0.01).

CONCLUSIONS

Expression of IL2 was significantly decreased in anti-TNF-treated CD patients in comparison to non-treated CD patients and controls. This novel finding may indicate a further mechanism of anti-TNF therapy in CD. Expression of IL17 was not influenced by presence of CD or anti-TNF therapy, which may partly explain the failure of recent clinical trials investigating anti-IL17 therapy in CD.

Autoimmune diseases association study with the KIAA1109-IL2-IL21 region in a Tunisian population

Autoimmune diseases (ADs) share several genetic factors resulting in similarity of disease mechanisms. For instance polymorphisms from the KIAA1109-interleukin 2 (IL2)-IL21 block in the 4q27 chromosome, has been associated with a number of autoimmune phenotypes. Here we performed a haplotype-based analysis of this AD related region in Tunisian patients. Ten single nucleotide polymorphisms (rs6534347, rs11575812, rs2069778, rs2069763, rs2069762, rs6852535, rs12642902, rs6822844, rs2221903, rs17005931) of the block were investigated in a cohort of 93 systemic lupus erythematosus (SLE), 68 ulcerative colitis (UC), 39 Crohn's disease (CD) patients and 162 healthy control subjects of Tunisian origin. In SLE population, haplotypes AGCAGGGTC, AGAAGAGTC, AGAAGGGTC and AGCCGAGTC provided significant evidence of association with SLE risk (p = 0.013, 0.028, 0.018 and 0.048, respectively). In the UC population, haplotype AGCCGGGTC provided a susceptibility effect for UC (p = 0.025). In the CD population, haplotype CAGGCC showed a protective effect against the development of CD (p = 0.038). Haplotype AAGGTT provided significant evidence to be associated with CD risk (p = 0.007). Our results support the existence of the associations found in the KIAA1109/IL2/IL21 gene region with ADs, thus confirms that the 4q27 locus may contribute to the genetic susceptibility of ADs in the Tunisian population.

Anti-TNF antibody-induced psoriasiform skin lesions in patients with inflammatory bowel disease are characterised by interferon-γ-expressing Th1 cells and IL-17A/IL-22-expressing Th17 cells and respond to anti-IL-12/IL-23 antibody treatment

BACKGROUND

We analysed incidence, predictors, histological features and specific treatment options of anti-tumour necrosis factor α (TNF-α) antibody-induced psoriasiform skin lesions in patients with inflammatory bowel diseases (IBD).

DESIGN

Patients with IBD were prospectively screened for anti-TNF-induced psoriasiform skin lesions. Patients were genotyped for IL23R and IL12B variants. Skin lesions were examined for infiltrating Th1 and Th17 cells. Patients with severe lesions were treated with the anti-interleukin (IL)-12/IL-23 p40 antibody ustekinumab.

RESULTS

Among 434 anti-TNF-treated patients with IBD, 21 (4.8%) developed psoriasiform skin lesions. Multiple logistic regression revealed smoking (p=0.007; OR 4.24, 95% CI 1.55 to 13.60) and an increased body mass index (p=0.029; OR 1.12, 95% CI 1.01 to 1.24) as main predictors for these lesions. Nine patients with Crohn's disease and with severe psoriasiform lesions and/or anti-TNF antibody-induced alopecia were successfully treated with the anti-p40-IL-12/IL-23 antibody ustekinumab (response rate 100%). Skin lesions were histologically characterised by infiltrates of IL-17A/IL-22-secreting T helper 17 (Th17) cells and interferon (IFN)-γ-secreting Th1 cells and IFN-α-expressing cells. IL-17A expression was significantly stronger in patients requiring ustekinumab than in patients responding to topical therapy (p=0.001). IL23R genotyping suggests disease-modifying effects of rs11209026 (p.Arg381Gln) and rs7530511 (p.Leu310Pro) in patients requiring ustekinumab.

CONCLUSIONS

New onset psoriasiform skin lesions develop in nearly 5% of anti-TNF-treated patients with IBD. We identified smoking as a main risk factor for developing these lesions. Anti-TNF-induced psoriasiform skin lesions are characterised by Th17 and Th1 cell infiltrates. The number of IL-17A-expressing T cells correlates with the severity of skin lesions. Anti-IL-12/IL-23 antibody therapy is a highly effective therapy for these lesions.

NF-κB Activation in T Helper 17 Cell Differentiation

CD28/T cell receptor ligation activates the NF-κB signaling cascade during CD4 T cell activation. NF-κB activation is required for cytokine gene expression and activated T cell survival and proliferation. Recently, many reports showed that NF-κB activation is also involved in T helper (Th) cell differentiation including Th17 cell differentiation. In this review, we discuss the current literature on NF-κB activation pathway and its effect on Th17 cell differentiation.

Excess IL-1 signaling enhances the development of Th17 cells by downregulating TGF-β-induced Foxp3 expression

IL-1R antagonist-deficient (Il1rn(-/-)) mice develop autoimmune arthritis in which IL-17A plays a crucial role. Although many studies have shown that Th17 cell differentiation is dependent on TGF-β and IL-6, we found that Th17 cells developed normally in Il1rn(-/-)Il6(-/-) mice in vivo. Then, we analyzed the mechanisms of Th17 cell differentiation in Il1rn(-/-)Il6(-/-) mice. We found that IL-21 production was increased in the lymph nodes of Il1rn(-/-) mice, naive Il6(-/-) CD4(+) T cells differentiated into Th17 cells when cultured with TGF-β and IL-21, and the differentiation was greatly enhanced when IL-1 was added to the culture. Th17 cell differentiation was not induced by either TGF-β or IL-1 alone or in combination. IL-21 induced IL-1R expression in naive CD4(+) T cells, and IL-1 inhibited TGF-β-induced Foxp3 expression, resulting in the promotion of Th17 cell differentiation. Furthermore, IL-1 augmented the expression of Th17 cell-specific transcription factors such as Nfkbiz and Batf. These results indicate that excess IL-1 signaling can overcome the requirement of IL-6 in the differentiation of Th17 cells by suppressing Foxp3 expression and inducing Th17 cell-specific transcription factors.

The Role of Tumour Necrosis Factor in the Pathogenesis of Immune-Mediated Diseases

Immune-mediated inflammatory diseases (IMIDs), such as rheumatoid arthritis, psoriatic arthritis, psoriasis, axial spondyloarthropathies, Crohn's disease, ulcerative colitis and juvenile idiopathic arthritis, comprise a group of chronic disorders characterized by an immune-mediated pathogenesis. Although at clinical presentation these diseases appear unrelated, they have been recognized to share similar pathogenic mechanisms. Data from epidemiological and genetic studies further support the concept that IMIDs are interrelated, as they can co-occur in the same patient and share a similar genetic susceptibility. The specific aetiologies of IMIDs remain unknown, but all are known to involve dysregulation of the immune system, including an over-expression of the pro-inflammatory cytokine tumour necrosis factor (TNF). The pivotal role played by TNF in the pathogenesis and pathophysiology of IMIDs has been documented by extensive preclinical and clinical investigations, and confirmed by the efficacy of anti-TNF biotechnological drugs, such as etanercept, infliximab and adalimumab, in the therapeutic management of these disorders. In this narrative review, we discuss the available data on the TNF-dependent pathogenesis of IMIDs and associations among the different disorders. Although much remains to be discovered about the pathogenesis and aetiology of IMIDs, their common inflammatory pathological features may explain why they can be successfully targeted by anti-TNF drugs. Among these, adalimumab, a fully human monoclonal antibody, has been approved for treatment ofnine distinct IMID indications and it is likely to become a valuable therapeutic tool for this complex cluster of chronic inflammatory disorders.

Intestinal DMBT1 expression is modulated by Crohn's disease-associated IL23R variants and by a DMBT1 variant which influences binding of the transcription factors CREB1 and ATF-2

OBJECTIVES

DMBT is an antibacterial pattern recognition and scavenger receptor. In this study, we analyzed the role of DMBT1 single nucleotide polymorphisms (SNPs) regarding inflammatory bowel disease (IBD) susceptibility and examined their functional impact on transcription factor binding and downstream gene expression.

METHODS

Seven SNPs in the DMBT1 gene region were analyzed in 2073 individuals including 818 Crohn's disease (CD) patients and 972 healthy controls in two independent case-control panels. Comprehensive epistasis analyses for the known CD susceptibility genes NOD2, IL23R and IL27 were performed. The influence of IL23R variants on DMBT1 expression was analyzed. Functional analysis included siRNA transfection, quantitative PCR, western blot, electrophoretic mobility shift and luciferase assays.

RESULTS

IL-22 induces DMBT1 protein expression in intestinal epithelial cells dependent on STAT3, ATF-2 and CREB1. IL-22 expression-modulating, CD risk-associated IL23R variants influence DMBT1 expression in CD patients and DMBT1 levels are increased in the inflamed intestinal mucosa of CD patients. Several DMBT1 SNPs were associated with CD susceptibility. SNP rs2981804 was most strongly associated with CD in the combined panel (p = 3.0 × 10(-7), OR 1.42; 95% CI 1.24-1.63). All haplotype groups tested showed highly significant associations with CD (including omnibus P-values as low as 6.1 × 10(-18)). The most strongly CD risk-associated, non-coding DMBT1 SNP rs2981804 modifies the DNA binding sites for the transcription factors CREB1 and ATF-2 and the respective genomic region comprising rs2981804 is able to act as a transcriptional regulator in vitro. Intestinal DMBT1 expression is decreased in CD patients carrying the rs2981804 CD risk allele.

CONCLUSION

We identified novel associations of DMBT1 variants with CD susceptibility and discovered a novel functional role of rs2981804 in regulating DMBT1 expression. Our data suggest an important role of DMBT1 in CD pathogenesis.

Celiac disease in a child with ulcerative colitis: a possible genetic association

Celiac disease and inflammatory bowel disease including ulcerative colitis (UC) and Crohn's disease are both immune-mediated enteropathies. It is rare for both celiac disease and inflammatory bowel disease to occur together in an individual patient. This association has been reported in adults, however, very rarely in children. Here, we report an unusual case of an 8-year-old child with a history of anemia and failure to thrive who presented with bloody diarrhea. His evaluation showed anemia, elevated inflammatory markers, and positive celiac antibodies. Endoscopic evaluation revealed partial duodenal villous atrophy and pancolitis. He was diagnosed with celiac disease and UC and responded well to a gluten-free diet and steroid/mesalamine therapy. The patient's genetic testing revealed markers showing susceptibility for both celiac disease and UC. It is important to be aware of this association as both conditions can present with similar clinical features, however, require different therapeutic approaches.

IRGM variants and susceptibility to inflammatory bowel disease in the German population

Background & Aims

Genome-wide association studies identified the autophagy gene IRGM to be strongly associated with Crohn's disease (CD) but its impact in ulcerative colitis (UC), its phenotypic effects and potential epistatic interactions with other IBD susceptibility genes are less clear which we therefore analyzed in this study.

Methodology/Principal Findings

Genomic DNA from 2060 individuals including 817 CD patients, 283 UC patients, and 961 healthy, unrelated controls (all of Caucasian origin) was analyzed for six IRGM single nucleotide polymorphisms (SNPs) (rs13371189, rs10065172 = p.Leu105Leu, rs4958847, rs1000113, rs11747270, rs931058). In all patients, a detailed genotype-phenotype analysis and testing for epistasis with the three major CD susceptibility genes NOD2, IL23R and ATG16L1 were performed.

Our analysis revealed an association of the IRGM SNPs rs13371189 (p = 0.02, OR 1.31 [95% CI 1.05–1.65]), rs10065172 = p.Leu105Leu (p = 0.016, OR 1.33 [95% CI 1.06–1.66]) and rs1000113 (p = 0.047, OR 1.27 [95% CI 1.01–1.61]) with CD susceptibility. There was linkage disequilibrium between these three IRGM SNPs. In UC, several IRGM haplotypes were weakly associated with UC susceptibility (p<0.05). Genotype-phenotype analysis revealed no significant associations with a specific IBD phenotype or ileal CD involvement. There was evidence for weak gene-gene-interaction between several SNPs of the autophagy genes IRGM and ATG16L1 (p<0.05), which, however, did not remain significant after Bonferroni correction.

Conclusions/Significance

Our results confirm IRGM as susceptibility gene for CD in the German population, supporting a role for the autophagy genes IRGM and ATG16L1 in the pathogenesis of CD.

Generation and characterization of human anti-human IL-21 neutralizing monoclonal antibodies

Interleukin-21 (IL-21) is a type I four-helical bundle cytokine that exerts a variety of significant effects on many hematopoietic cells, including T and B lymphocytes and natural killer cells. IL-21 is produced predominantly by CD4+ T cells and natural killer T cells and, when aberrantly overexpressed, appears to play important roles in a wide variety of autoimmune disorders. To generate potential therapeutic reagents capable of inhibiting IL-21 for clinical use, we immunized human immunoglobulin transgenic mice with IL-21 and then identified and cloned a panel of human anti-human IL-21 binding monoclonal antibodies. IL-21 neutralizing and IL-21-binding, non-neutralizing antibodies were assigned to distinct epitope "bins" based on surface plasmon resonance competition studies. The most potent neutralizing antibodies had extremely high (sub pM) affinity for IL-21 and were able to block IL-21 activity in various biological assays using either an IL-21R-transfected pre-B-cell line or primary human B cells, and their neutralizing activity was, in some cases, superior to that of a soluble form of the high affinity heterodimeric IL-21 receptor. Characterization of this panel of IL-21 antibodies provided the basis for the selection of a therapeutic candidate antibody capable of inhibiting IL-21 activity for the treatment of autoimmune and inflammatory diseases.

Profiles of circulating cytokines in patients with Crohn's disease under maintenance therapy with infliximab

BACKGROUND AND AIMS

The effects of maintenance infliximab for Crohn's disease vary widely among patients. The aim of this study was to examine the cytokine profiles and to identify possible markers predictive of therapeutic effect of maintenance infliximab.

METHODS

Cytokine profiles of 35 Crohn's disease patients under maintenance infliximab therapy were analyzed prospectively. Blood samples were obtained prior to, and 2 and 6 weeks after infliximab infusion. Circulating cytokine values of interleukin (IL)-23, IL-17A, IL-12, IL-6, interferon gamma (IFN-γ), and tumor necrosis factor alpha (TNF-α) were compared according to the disease activity and therapeutic efficacy. Patients were classified into either the active or quiescent phase according to their disease activity at baseline. Patients were also divided into a sustained response group and non-sustained response group according to therapeutic efficacy of infliximab determined 2 and 6 weeks after infliximab infusion.

RESULTS

At baseline, serum levels of IL-23 (p<0.05), IL-17A (p<0.01), IFN-γ (p<0.05), and IL-6 (p<0.01) were significantly higher in active Crohn's disease than in quiescent disease. These cytokine levels remained unchanged during the follow-up period. When serum cytokine levels were compared between groups classified by therapeutic efficacy of infliximab, patients in the non-sustained response group had a significantly higher level of serum IL-17A than those in the sustained response group (p<0.05). There were also trends toward higher serum IL-23 and IL-12 in the former than in the latter.

CONCLUSION

Higher levels of IL-17A, IL-23, and IL-12 at baseline may be predictive markers for poor therapeutic response to maintenance infliximab therapy.

The IL-23/IL-17 pathway in inflammatory bowel disease

The etiology of inflammatory bowel disease is unknown but available evidence suggests that a deregulated immune response towards the commensal bacterial flora is responsible for intestinal inflammation in genetically predisposed individuals. IL-23 promotes expansion and maintenance of Th17 cells, which secrete the proinflammatory cytokine IL-17 and have been implicated in the pathogenesis of many chronic inflammatory disorders. Recent studies have shown that IL-23 also acts on cells of the innate immune system that can contribute to inflammatory cytokine production and tissue inflammation. A role for the IL-23/IL-17 pathway in the pathogenesis of chronic intestinal inflammation in inflammatory bowel disease has emerged from both animal and human studies. Here we aim to review the recent advances in this rapidly moving field.

Analysis of IL12B gene variants in inflammatory bowel disease

BACKGROUND

IL12B encodes the p40 subunit of IL-12, which is also part of IL-23. Recent genome-wide association studies identified IL12B and IL23R as susceptibility genes for inflammatory bowel disease (IBD). However, the phenotypic effects and potential gene-gene interactions of IL12B variants are largely unknown.

METHODOLOGY/PRINCIPAL FINDINGS

We analyzed IL12B gene variants regarding association with Crohn's disease (CD) and ulcerative colitis (UC). Genomic DNA from 2196 individuals including 913 CD patients, 318 UC patients and 965 healthy, unrelated controls was analyzed for four SNPs in the IL12B gene region (rs3212227, rs17860508, rs10045431, rs6887695). Our analysis revealed an association of the IL12B SNP rs6887695 with susceptibility to IBD (p = 0.035; OR 1.15 [95% CI 1.01-1.31] including a trend for rs6887695 for association with CD (OR 1.41; [0.99-1.31], p = 0.066) and UC (OR 1.18 [0.97-1.43], p = 0.092). CD patients, who were homozygous C/C carriers of this SNP, had significantly more often non-stricturing, non-penetrating disease than carriers of the G allele (p = 6.8×10(-5); OR = 2.84, 95% CI 1.66-4.84), while C/C homozygous UC patients had less often extensive colitis than G allele carriers (p = 0.029; OR = 0.36, 95% CI 0.14-0.92). In silico analysis predicted stronger binding of the minor C allele of rs6887695 to the transcription factor RORα which is involved in Th17 differentiation. Differences regarding the binding to the major and minor allele sequence of rs6887695 were also predicted for the transcription factors HSF1, HSF2, MZF1 and Oct-1. Epistasis analysis revealed weak epistasis of the IL12B SNP rs6887695 with several SNPs (rs11889341, rs7574865, rs7568275, rs8179673, rs10181656, rs7582694) in the STAT4 gene which encodes the major IL-12 downstream transcription factor STAT4 (p<0.05) but there was no epistasis between IL23R and IL12B variants.

CONCLUSIONS/SIGNIFICANCE

The IL12B SNP rs6887695 modulates the susceptibility and the phenotype of IBD, although the effect on IBD susceptibilty is less pronounced than that of IL23R gene variants.

PTPN2 gene variants are associated with susceptibility to both Crohn's disease and ulcerative colitis supporting a common genetic disease background

BACKGROUND

Genome-wide association studies identified PTPN2 (protein tyrosine phosphatase, non-receptor type 2) as susceptibility gene for inflammatory bowel diseases (IBD). However, the exact role of PTPN2 in Crohn's disease (CD) and ulcerative colitis (UC) and its phenotypic effect are unclear. We therefore performed a detailed genotype-phenotype and epistasis analysis of PTPN2 gene variants.

METHODOLOGY/PRINCIPAL FINDINGS

Genomic DNA from 2131 individuals of Caucasian origin (905 patients with CD, 318 patients with UC, and 908 healthy, unrelated controls) was analyzed for two SNPs in the PTPN2 region (rs2542151, rs7234029) for which associations with IBD were found in previous studies in other cohorts. Our analysis revealed a significant association of PTPN2 SNP rs2542151 with both susceptibility to CD (p = 1.95×10⁻⁵; OR 1.49 [1.34-1.79]) and UC (p = 3.87×10⁻², OR 1.31 [1.02-1.68]). Moreover, PTPN2 SNP rs7234029 demonstrated a significant association with susceptibility to CD (p = 1.30×10⁻³; OR 1.35 [1.13-1.62]) and a trend towards association with UC (p = 7.53×10⁻²; OR 1.26 [0.98-1.62]). Genotype-phenotype analysis revealed an association of PTPN2 SNP rs7234029 with a stricturing disease phenotype (B2) in CD patients (p = 6.62×10⁻³). Epistasis analysis showed weak epistasis between the ATG16L1 SNP rs2241879 and PTPN2 SNP rs2542151 (p = 0.024) in CD and between ATG16L1 SNP rs4663396 and PTPN2 SNP rs7234029 (p = 4.68×10⁻³) in UC. There was no evidence of epistasis between PTPN2 and NOD2 and PTPN2 and IL23R. In silico analysis revealed that the SNP rs7234029 modulates potentially the binding sites of several transcription factors involved in inflammation including GATA-3, NF-κB, C/EBP, and E4BP4.

CONCLUSIONS/SIGNIFICANCE

Our data confirm the association of PTPN2 variants with susceptibility to both CD and UC, suggesting a common disease pathomechanism for these diseases. Given recent evidence that PTPN2 regulates autophagosome formation in intestinal epithelial cells, the potential link between PTPN2 and ATG16L1 should be further investigated.

Th17-related genes and celiac disease susceptibility

Th17 cells are known to be involved in several autoimmune or inflammatory diseases. In celiac disease (CD), recent studies suggest an implication of those cells in disease pathogenesis. We aimed at studying the role of genes relevant for the Th17 immune response in CD susceptibility. A total of 101 single nucleotide polymorphisms (SNPs), mainly selected to cover most of the variability present in 16 Th17-related genes (IL23R, RORC, IL6R, IL17A, IL17F, CCR6, IL6, JAK2, TNFSF15, IL23A, IL22, STAT3, TBX21, SOCS3, IL12RB1 and IL17RA), were genotyped in 735 CD patients and 549 ethnically matched healthy controls. Case-control comparisons for each SNP and for the haplotypes resulting from the SNPs studied in each gene were performed using chi-square tests. Gene-gene interactions were also evaluated following different methodological approaches. No significant results emerged after performing the appropriate statistical corrections. Our results seem to discard a relevant role of Th17 cells on CD risk.

The Impact of PPARγ Genetic Variants on IBD Susceptibility and IBD Disease Course

PPARγ is a nuclear receptor that regulates numerous pathways including cytokine expression and immune responses and plays an important role in controlling colon inflammation. We aimed at determining the occurring PPARγ SNPs, at predicting the haplotypes, and at determining the frequency outcome in inflammatory bowel disease (IBD) patients in comparison with healthy controls. We determined genetic variants in the coding exons and flanking intronic sequences of the NR1C3 gene in 284 IBD patients and 194 controls and predicted NR1C3 haplotypes via bioinformatic analysis. We investigated whether certain NR1C3 variants are associated with susceptibility to IBD or its disease course. None of the detected 22 NR1C3 variants were associated with IBD. Two variants with allelic frequencies over 1% were included in haplotype/diplotype analyses. None of the NR3C1 haplotypes showed association with IBD development or disease course. We conclude that NR1C3 haplotypes are not related to IBD susceptibility or IBD disease activity.

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.

The role of osteopontin (OPN/SPP1) haplotypes in the susceptibility to Crohn's disease

BACKGROUND

Osteopontin represents a multifunctional molecule playing a pivotal role in chronic inflammatory and autoimmune diseases. Its expression is increased in inflammatory bowel disease (IBD). The aim of our study was to analyze the association of osteopontin (OPN/SPP1) gene variants in a large cohort of IBD patients.

METHODOLOGY/PRINCIPAL FINDINGS

Genomic DNA from 2819 Caucasian individuals (n = 841 patients with Crohn's disease (CD), n = 473 patients with ulcerative colitis (UC), and n = 1505 healthy unrelated controls) was analyzed for nine OPN SNPs (rs2728127, rs2853744, rs11730582, rs11739060, rs28357094, rs4754 = p.Asp80Asp, rs1126616 = p.Ala236Ala, rs1126772 and rs9138). Considering the important role of osteopontin in Th17-mediated diseases, we performed analysis for epistasis with IBD-associated IL23R variants and analyzed serum levels of the Th17 cytokine IL-22. For four OPN SNPs (rs4754, rs1126616, rs1126772 and rs9138), we observed significantly different distributions between male and female CD patients. rs4754 was protective in male CD patients (p = 0.0004, OR = 0.69). None of the other investigated OPN SNPs was associated with CD or UC susceptibility. However, several OPN haplotypes showed significant associations with CD susceptibility. The strongest association was found for a haplotype consisting of the 8 OPN SNPs rs2728127-rs2853744-rs11730582-rs11439060-rs28357094-rs112661-rs1126772-rs9138 (omnibus p-value = 2.07×10⁻⁸). Overall, the mean IL-22 secretion in the combined group of OPN minor allele carriers with CD was significantly lower than that of CD patients with OPN wildtype alleles (p = 3.66×10⁻⁵). There was evidence for weak epistasis between the OPN SNP rs28357094 with the IL23R SNP rs10489629 (p = 4.18×10⁻²) and between OPN SNP rs1126616 and IL23R SNP rs2201841 (p = 4.18×10⁻²) but none of these associations remained significant after Bonferroni correction.

CONCLUSIONS/SIGNIFICANCE

Our study identified OPN haplotypes as modifiers of CD susceptibility, while the combined effects of certain OPN variants may modulate IL-22 secretion.

Th17-related cytokines: new players in the control of chronic intestinal inflammation

Crohn's disease (CD) and ulcerative colitis (UC), the main forms of inflammatory bowel diseases (IBD) in man, are thought to be caused by an excessive and poorly controlled immune response that is directed against components of the normal microflora. The exact sequence of events by which this pathological process is triggered and maintained is not fully understood, but studies in experimental models of IBD and data emerging from recent clinical trials indicate that T cell-derived cytokines are crucial mediators of the tissue damage. Although CD and UC have been traditionally considered two typical examples of T helper (Th)1 or Th2-associated disease respectively, it is now known that CD- and UC-related inflammation is also marked by enhanced production of cytokines made by a distinct subset of Th cells, termed Th17 cells. Th17 cytokines can have both tissue-protective and inflammatory effects in the gut and there is evidence that Th17 cells can alter their cytokine program according to the stimuli received and convert into Th1-producing cells. These novel findings have contributed to advancing our understanding of mechanisms of gut tissue damage and open new avenues for development of therapeutic strategies in IBD.

Fine-mapping and transethnic genotyping establish IL2/IL21 genetic association with lupus and localize this genetic effect to IL21

OBJECTIVE

Genetic association of the IL2/IL21 region at chromosome 4q27 has previously been reported in lupus and a number of autoimmune and inflammatory diseases. This study was undertaken to determine whether this genetic effect could be localized, using a very large cohort of lupus patients and controls.

METHODS

We genotyped 45 tag single-nucleotide polymorphisms (SNPs) across the IL2/IL21 locus in 2 large independent lupus sample sets. We studied a set of subjects of European descent consisting of 4,248 lupus patients and 3,818 healthy controls, and an African American set of 1,569 patients and 1,893 healthy controls. Imputation in 3,004 additional controls from the Wellcome Trust Case Control Consortium was also performed. Genetic association between the genotyped markers was determined, and pairwise conditional analysis was performed to localize the independent genetic effect in the IL2/IL21 locus in lupus.

RESULTS

We established and confirmed the genetic association between IL2/IL21 and lupus. Using conditional analysis and transethnic mapping, we localized the genetic effect in this locus to 2 SNPs in high linkage disequilibrium: rs907715 located within IL21 (odds ratio 1.16 [95% confidence interval 1.10-1.22], P=2.17×10(-8)) and rs6835457 located in the 3'-untranslated flanking region of IL21 (odds ratio 1.11 [95% confidence interval 1.05-1.17], P=9.35×10(-5)).

CONCLUSION

Our findings establish the genetic association between lupus and IL2/IL21 with a genome-wide level of significance. Further, our findings indicate that this genetic association within the IL2/IL21 linkage disequilibrium block is localized to IL21. If other autoimmune IL2/IL21 genetic associations are similarly localized, then the IL21 risk alleles would be predicted to operate by a fundamental mechanism that influences the course of a number of autoimmune disease processes.

CEACAM6 gene variants in inflammatory bowel disease

BACKGROUND

The carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) acts as a receptor for adherent-invasive E. coli (AIEC) and its ileal expression is increased in patients with Crohn's disease (CD). Given its contribution to the pathogenesis of CD, we aimed to investigate the role of genetic variants in the CEACAM6 region in patients with inflammatory bowel diseases (IBD).

METHODOLOGY

In this study, a total of 2,683 genomic DNA samples (including DNA from 858 CD patients, 475 patients with ulcerative colitis (UC), and 1,350 healthy, unrelated controls) was analyzed for eight CEACAM6 SNPs (rs10415946, rs1805223 = p.Pro42Pro, rs4803507, rs4803508, rs11548735 = p.Gly239Val, rs7246116 = pHis260His, rs2701, rs10416839). In addition, a detailed haplotype analysis and genotype-phenotype analysis were performed. Overall, our genotype analysis did not reveal any significant association of the investigated CEACAM6 SNPs and haplotypes with CD or UC susceptibility, although certain CEACAM6 SNPs modulated CEACAM6 expression in intestinal epithelial cell lines. Despite its function as receptor of AIEC in ileal CD, we found no association of the CEACAM6 SNPs with ileal or ileocolonic CD. Moreover, there was no evidence of epistasis between the analyzed CEACAM6 variants and the main CD-associated NOD2, IL23R and ATG16L1 variants.

CONCLUSIONS

This study represents the first detailed analysis of CEACAM6 variants in IBD patients. Despite its important role in bacterial attachment in ileal CD, we could not demonstrate a role for CEACAM6 variants in IBD susceptibility or regarding an ileal CD phenotype. Further functional studies are required to analyze if these gene variants modulate ileal bacterial attachment.

Bacterial agents in spondyloarthritis: a destiny from diversity?

The spondyloarthritides (SpAs) are a group of diseases that share clinical, radiographic and laboratory features; these arthritides also display a tendency for family aggregation. Given the intimate relationship that these types of arthritis share, it suggests that the SpAs might share a common aetiology. Of all the SpAs, the role of bacteria is most clearly defined in reactive arthritis. Tremendous recent insights into the pathophysiology of reactive arthritis have been made, demonstrating that the causative bacteria play a much more complex role than previously thought. The bacteria that are proven to cause reactive arthritis, one of the five types of SpA, will be reviewed and their role in the pathophysiology of reactive arthritis will be examined. The speculative data suggesting links between various other bacteria and the other types of SpAs will be critically analysed. Although these data are not definitive, when viewed using the paradigm that the SpAs might actually represent a common end point from several diverse starting points, they are provocative, suggesting that bacteria might, indeed, be aetiological for the entire group of SpAs.

Effect of hookworm infection on wheat challenge in celiac disease--a randomised double-blinded placebo controlled trial

BACKGROUND AND AIMS

The association between hygiene and prevalence of autoimmune disease has been attributed in part to enteric helminth infection. A pilot study of experimental infection with the hookworm Necator americanus was undertaken among a group of otherwise healthy people with celiac disease to test the potential of the helminth to suppress the immunopathology induced by gluten.

METHODS

In a 21-week, double-blinded, placebo-controlled study, we explored the effects of N. americanus infection in 20 healthy, helminth-naïve adults with celiac disease well controlled by diet. Staged cutaneous inoculations with 10 and 5 infective 3(rd) stage hookworm larvae or placebo were performed at week-0 and -12 respectively. At week-20, a five day oral wheat challenge equivalent to 16 grams of gluten per day was undertaken. Primary outcomes included duodenal Marsh score and quantification of the immunodominant α-gliadin peptide (QE65)-specific systemic interferon-γ-producing cells by ELISpot pre- and post-wheat challenge.

RESULTS

Enteric colonisation with hookworm established in all 10 cases, resulting in transiently painful enteritis in 5. Chronic infection was asymptomatic, with no effect on hemoglobin levels. Although some duodenal eosinophilia was apparent, hookworm-infected mucosa retained a healthy appearance. In both groups, wheat challenge caused deterioration in both primary and several secondary outcomes.

CONCLUSIONS

Experimental N. americanus infection proved to be safe and enabled testing its effect on a range of measures of the human autoimmune response. Infection imposed no obvious benefit on pathology.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00671138.

Advances in celiac disease

PURPOSE OF REVIEW

To critically summarize recent research in celiac disease.

RECENT FINDINGS

There are new serological markers with potential use not only in the diagnosis of celiac disease but also as important follow-up tools. As our understanding of celiac disease increases with further isolation of nonhuman leukocyte antigen genes and clarification of the intracellular pathways that underlie its pathogenesis, there are new modalities which will not only allow improved risk stratification of individuals but also facilitate the development of novel therapeutic agents.

SUMMARY

Small bowel biopsy remains the gold standard for both diagnosis and monitoring. A gluten-free diet currently remains the only treatment option, with potential other options being discovered such as glutenases for predigestion of gluten.

Differential mucosal expression of Th17-related genes between the inflamed colon and ileum of patients with inflammatory bowel disease

BACKGROUND

Immunological and genetic findings implicate Th17 effector cytokines in the pathogenesis of inflammatory bowel disease (IBD). Expression of Th17 pathway-associated genes is mainly studied in colonic disease. The present study assessed the mRNA expression levels of Th17 effector cytokines (IL17A, IL17F, IL21, IL22 and IL26) and genes involved in differentiation (IL6, IL1B, TGFB1, IL23A and STAT3) and recruitment of Th17 cells (CCR6 and CCL20) by quantitative real-time PCR analysis of colonic and ileal biopsies from 22 healthy control subjects, 26 patients with Crohn's disease (CD) and 12 patients with ulcerative colitis (UC). Inflammation was quantified by measuring expression of the inflammatory mediators IL8 and TNF.

RESULTS

Evaluation of mRNA expression levels in colonic and ileal control samples revealed that TNF, TGFB1, STAT3 and CCR6 were expressed at higher levels in the ileum than in the colon. Expression of all the Th17 pathway-associated genes was increased in inflamed colonic samples. The increased expression of these genes was predominantly observed in samples from UC patients and was associated with more intense inflammation. Although increased expression of IL17A, IL17F, IL21 and IL26 was detected in inflamed ileal samples, expression of the indispensable Th17 cell differentiation factors TGFB1 and IL23A, the signaling molecule STAT3 and the Th17 recruitment factors CCR6 and CCL20 were unchanged.

CONCLUSIONS

Our findings suggest that immune regulation is different in colonic and ileal disease, which might have important consequences for therapeutic intervention.