Identification of IL-27 as a novel regulator of major histocompatibility complex class I and class II expression, antigen presentation, and processing in intestinal epithelial cells.

Antigen presentation via major histocompatibility complex (MHC) class I and class II receptors plays a fundamental role in T cell-mediated adaptive immunity. A dysregulation of this fine-tuned recognition might result in the development of autoimmune diseases such as inflammatory bowel diseases that are characterized by chronic relapsing inflammation of the intestinal tract and a damaged intestinal epithelial barrier. While MHCII receptors are usually expressed by professional antigen presenting cells (APC) only, there is increasing evidence that non-immune cells such as intestinal epithelial cells (IEC) might express MHCII upon stimulation with IFN-γ and thus act as non-professional APC. However, little is known about other factors regulating intestinal epithelial MHC expression. Here, we identify IL-27 as an inducer of different MHCI and MHCII receptor subtypes and the invariant chain (CD74/li) in IEC via the STAT1/IRF1/CIITA axis. CIITA, MHCII, and CD74 expression was significantly increased in IEC from Crohn's disease (CD) patients with active disease compared to controls or CD patients in remission. IEC phagocytosed and digested external antigens and apoptotic cells. IL-27 strongly stimulated antigen processing via the immunoproteasome in a IRF1-dependent manner. In co-culture experiments, antigen-primed IEC strongly enhanced lymphocyte proliferation and IL-2 secretion, dependent on direct cell-cell contact. IL-27 pretreatment of IEC significantly increased CD4+ T cell proliferation and reduced IL-2 levels in lymphocytes in coculture. In summary, we identified IL-27 as a novel regulator of IEC antigen processing and presentation via MHCI and MHCII receptors, underscoring the importance of IEC as non-professional APC.

Characterization of universal chromatic resin-based composites in terms of cell toxicity and viscoelastic behavior.

OBJECTIVES: A current trend to simplify dental restorative procedures is toward using universal chromatic light-cured resin-based composites (RBCs) designed to adapt esthetically to various clinical situations. This study offers a comparative characterization of the mechanical and cytotoxic behavior of such materials that use different techniques to adjust their optical properties (e.g., structural color instead of pigment addition), have different filler systems but are based on a comparable organic matrix. METHODS: The structural appearance of the filler systems was assessed by scanning electron microscopy. Various quasi-static and viscoelastic parameters were evaluated at clinically relevant frequencies (0.5-5 Hz) using an instrumented indentation test with a Dynamic Mechanical Analysis (DMA) module. Cytotoxicity on human gingival fibroblasts (HGF-1), when exposed to eluates from tested RBCs specimens (up to one month), was assessed using a WST-1 colorimetric proliferation assay. Multifactor analysis of variance was applied to compare the parameters of interest (Martens, Vickers, and indentation hardness; elastic and total indentation work; creep, indentation depth; storage, loss, and indentation moduli; loss factor; cell viability) between analyzed RBCs, loading frequencies, and eluate age. RESULTS: Structural particularities of the filler systems are directly reflected in the mechanical behavior of the analyzed materials. Changes in the filler system, necessary to achieve structural color, generally resulted in lower mechanical properties but a better ability to absorb shock. In contrast, the cytotoxicity was comparable. SIGNIFICANCE: Based on the performed characterization, universal chromatic RBCs fits in the conventional RBCs class to expect comparable clinical behavior.

Iron Deficiency in Inflammatory Bowel Disease Is Associated With Low Levels of Vitamin D Modulating Serum Hepcidin and Intestinal Ceruloplasmin Expression.

INTRODUCTION: Iron deficiency and vitamin D deficiency are common comorbidities in inflammatory bowel disease (IBD). Accumulating evidence indicates that active 1,25-dihydroxyvitamin D (1,25(OH)D) may enhance iron absorption by suppressing hepcidin. We investigated the influence of vitamin D on iron metabolism in patients with IBD and on the expression of genes facilitating intestinal epithelial iron absorption. METHODS: Iron parameters and serum levels of 25-hydroxyvitamin D (25(OH)D), 1,25(OH)D, and hepcidin were measured in 104 adult patients with IBD (67 with Crohn's disease and 37 with ulcerative colitis). Genes involved in iron absorption were tested for induction by 1,25(OH)D in Caco-2 cells, which resemble the small intestinal epithelium. RESULTS: In multiple regression models controlling for age, sex, body mass index, smoking status, disease activity, and C-reactive protein levels, low 25(OH)D levels were associated with iron deficiency in patients with IBD (ß [SE] = -0.064 [0.030], P = 0.029). Vitamin D sufficiency was associated with increased levels of ferritin (ß [SE] = 0.25 [0.11], P = 0.024) and transferrin saturation (ß [SE] = 8.41 [4.07], P = 0.044). Higher 1,25(OH)D:25(OH)D ratios were associated with lower hepcidin levels (ß [SE] = -4.31 [1.67], P = 0.012). Especially in Crohn's disease, increased 1,25(OH)D correlated with higher transferrin saturation (ß [SE] = 0.43 [0.18], P = 0.027). Furthermore, 1,25(OH)D strongly induced the expression of the ferroxidase ceruloplasmin in Caco-2 cells. DISCUSSION: Low vitamin D levels in IBD correlate with iron deficiency. Vitamin D may ameliorate iron deficiency, potentially by downregulating hepcidin and upregulating ceruloplasmin, enhancing intestinal iron absorption.

Impact of ultra-fast (3 s) light-cure on cell toxicity and viscoelastic behavior in a dental resin-based composite with RAFT-mediated polymerization.

OBJECTIVE: The aim of the study was to determine the effects of ultra-fast (3 s) light-curing on the viscoelastic behaviour at clinically relevant frequencies, and cell toxicity, in a resin-based composite (RBC) with reversible addition-fragmentation-chain transfer (RAFT) mediated polymerization. METHODS: Three different protocols were used to cure cylindrical samples (height = 4 mm, Ï´ = 5 mm), including ultra-fast (3s) cure with high radiant emittance, 10 s and 20 s cure with moderate radiant emittance. The properties of the light curing device were evaluated in all curing protocols by spectrophotometry up to an exposure distance of 10 mm. The light transmission through the samples was determined in real-time with the same spectrophotometer. Absorbance was calculated as a function of wavelength. The quasi-static (indentation hardness/HIT, indentation modulus/EIT) and viscoelastic (storage modulus/E', loss modulus/E″, loss factor/tan Î´) material behavior was determined in an instrumented indentation test with a DMA (Dynamic Mechanical Analysis) module for 10 frequencies (0.5-5 Hz) by profiling the center of the samples in 330 µm steps from top to bottom. Cellular toxicity on human gingival fibroblast (HGF-1) was assessed using a WST-1 colorimetric assay after incubation time of up to 3 months. One and multiple-way analysis of variance (ANOVA) with Tukey honestly significant difference (HSD) post-hoc tests (α = 0.05) were applied. RESULTS: The irradiance transmitted through a 4 mm high sample was less than 7% of the incident irradiance, and the absorbance was similar for all curing protocols, showing a decrease with wavelength. Similar quasi-static and viscoelastic parameters were observed regardless of the curing protocol. HIT increased slightly and EIT, E', E″ and tan Î´ decreased with frequency. Occasionally, slightly higher confidence intervals were observed for the ultra-fast curing group, which were related to a potential accumulation of stress. The curing protocol had no effect on cell viability (p = 0.326) but the eluate age (p < 0.001, ηP2 = 0.879) did. None of the groups showed cell toxicity at any point in time with respect to the corresponding negative control. CONCLUSIONS: The ultra-fast curing with high irradiance induced no cell toxicity and an equivalent viscoelastic behavior as with conventional curing protocols in a RAFT-modified RBC.

Development of a uniform, very aggressive disease phenotype in all homozygous carriers of the NOD2 mutation p.Leu1007fsX1008 with Crohn's disease and active smoking status resulting in ileal stenosis requiring surgery.

BACKGROUND: NOD2 variants are the strongest genetic predictors for susceptibility to Crohn's disease (CD). However, the clinical value of NOD2 on an individual patient level remains controversial. We aimed to define the predictive power of the major NOD2 mutations regarding complicated CD in a large single center cohort. METHODS: 1076 CD patients were prospectively genotyped for the three common CD-associated NOD2 mutations rs2066844, rs2066845, and rs2066847, followed by detailed genotype-phenotype analyses. RESULTS: Overall, 434 CD patients (40.3%) carried at least one of the three main NOD2 mutations. A significantly higher minor allele frequency (15.6%) of the NOD2 frameshift mutation p.Leu1007fsX1008 (rs2066847) was seen in patients with aggressive disease compared to 8.2% in patients with mild disease (p = 2.6 x 10-5). Moreover, a total of 54 CD patients (5.0%) were homozygous for this NOD2 frameshift mutation. 100% of these patients had ileal disease compared to 82% of NOD2 wild-type carriers (p<0.0001). In homozygous carriers of the NOD2 frameshift mutation, 87% presented with ileal stenosis, 68.5% had fistulas, and 72.2% required CD-related surgery despite immunosuppressive therapy in 87% of these patients. All homozygous carriers of the 1007fs mutation who were active smokers had ileal stenosis and required CD-related surgery. CONCLUSION: Homozygosity for Leu1007fsX1008 is an excellent biomarker for predicting complicated CD on an individual patient level. Active smoking and homozygosity for this mutation is associated with a 100% risk for developing ileal stenosis requiring CD-related surgery. In these patients, smoking cessation and early initiation of immunosuppressive strategies may be beneficial.

The NOD2 Single Nucleotide Polymorphism rs72796353 (IVS4+10 A>C) Is a Predictor for Perianal Fistulas in Patients with Crohn's Disease in the Absence of Other NOD2 Mutations.

BACKGROUND: A previous study suggested an association of the single nucleotide polymorphism (SNP) rs72796353 (IVS4+10 A>C) in the NOD2 gene with susceptibility to Crohn's disease (CD). However, this finding has not been confirmed. Given that NOD2 variants still represent the most important predictors for CD susceptibility and phenotype, we evaluated the association of rs72796353 with inflammatory bowel disease (IBD) susceptibility and the IBD phenotype. METHODOLOGY: Genomic DNA from 2256 Caucasians, including 1073 CD patients, 464 patients with ulcerative colitis (UC), and 719 healthy controls, was genotyped for the NOD2 SNP rs72796353 and the three main CD-associated NOD2 mutations rs2066844, rs2066845, and rs2066847. Subsequently, IBD association and genotype-phenotype analyses were conducted. RESULTS: In contrast to the strong associations of the NOD2 SNPs rs2066844 (p=3.51 x 10(-3)), rs2066845 (p=1.54 x 10(-2)), and rs2066847 (p=1.61 x 10(-20)) with CD susceptibility, no significant association of rs72796353 with CD or UC susceptibility was found. However, in CD patients without the three main CD-associated NOD2 mutations, rs72796353 was significantly associated with the development of perianal fistulas (p=2.78 x 10(-7), OR 5.27, [95% CI 2.75-10.12] vs. NOD2 wild-type carriers). CONCLUSION/SIGNIFICANCE: Currently, this study represents the largest genotype-phenotype analysis of the impact of the NOD2 variant rs72796353 on the disease phenotype in IBD. Our data demonstrate that in CD patients the IVS4+10 A>C variant is strongly associated with the development of perianal fistulas. This association is particularly pronounced in patients who are not carriers of the three main CD-associated NOD2 mutations, suggesting rs72796353 as additional genetic marker for the CD disease behaviour.

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.

IL-17A alone weakly affects the transcriptome of intestinal epithelial cells but strongly modulates the TNF-α-induced expression of inflammatory mediators and inflammatory bowel disease susceptibility genes.

BACKGROUND: In contrast to anti-TNF-α antibodies, anti-IL-17A antibodies lacked clinical efficacy in a trial with patients suffering from Crohn's disease. We therefore analyzed how IL-17A modulates the inflammatory response elicited by TNF-α in intestinal epithelial cells (IEC). METHODS: Target mRNA levels in IEC and colonic biopsies were assessed by RNA microarray and quantitative real-time PCR. Signaling pathways were analyzed using receptor neutralization and pharmacological inhibitors. Target protein levels were determined by immunoblotting. RESULTS: Microarray analysis demonstrated that IL-17A alone is a weak inducer of gene expression in IEC (29 regulated transcripts), but significantly affected the TNF-α-induced expression of 547 genes, with strong amplification of proinflammatory chemokines and cytokines (>200-fold increase of CCL20, CXCL1, and CXCL8). Interestingly, IL-17A differentially modulated the TNF-α-induced expression of several inflammatory bowel disease susceptibility genes in IEC (increase of JAK2 mRNA, decrease of FUT2, ICAM1, and LTB mRNA). Negative regulation of ICAM-1 by IL-17A was verified on protein level. The significance of these findings is emphasized by inflamed lesions of patients with inflammatory bowel disease demonstrating significant correlations (P < 0.01, Rho, 0.57-0.85) for JAK2, ICAM1, and LTB mRNA with IL17A and TNF mRNA. CONCLUSIONS: Our study demonstrates the modulation of inflammatory bowel disease susceptibility gene mRNA in IEC as a novel important property of IL-17A. Given the weak impact of sole IL-17A stimulation on IEC target gene expression, our study provides an important explanation for the lack of clinical efficacy of sole IL-17A neutralization, but suggests a beneficial effect of combined IL-17A/TNF-α that is currently in clinical development.

Oncostatin M mediates STAT3-dependent intestinal epithelial restitution via increased cell proliferation, decreased apoptosis and upregulation of SERPIN family members.

OBJECTIVE: Oncostatin M (OSM) is produced by activated T cells, monocytes, and dendritic cells and signals through two distinct receptor complexes consisting of gp130 and LIFR (I) or OSMR-ß and gp130 (II), respectively. Aim of this study was to analyze the role of OSM in intestinal epithelial cells (IEC) and intestinal inflammation. METHODS: OSM expression and OSM receptor distribution was analyzed by PCR and immunohistochemistry experiments, signal transduction by immunoblotting. Gene expression studies were performed by microarray analysis and RT-PCR. Apoptosis was measured by caspases-3/7 activity. IEC migration and proliferation was studied in wounding and water soluble tetrazolium assays. RESULTS: The IEC lines Caco-2, DLD-1, SW480, HCT116 and HT-29 express mRNA for the OSM receptor subunits gp130 and OSMR-ß, while only HCT116, HT-29 and DLD-1 cells express LIFR mRNA. OSM binding to its receptor complex activates STAT1, STAT3, ERK-1/2, SAPK/JNK-1/2, and Akt. Microarray analysis revealed 79 genes that were significantly up-regulated (adj.-p ≤ 0.05) by OSM in IEC. Most up-regulated genes belong to the functional categories "immunity and defense" (p = 2.1 × 10(-7)), "apoptosis" (p = 3.7 × 10(-4)) and "JAK/STAT cascade" (p = 3.4 × 10(-6)). Members of the SERPIN gene family were among the most strongly up-regulated genes. OSM significantly increased STAT3- and MEK1-dependent IEC cell proliferation (p<0.05) and wound healing (p = 3.9 × 10(-5)). OSM protein expression was increased in colonic biopsies of patients with active inflammatory bowel disease (IBD). CONCLUSIONS: OSM promotes STAT3-dependent intestinal epithelial cell proliferation and wound healing in vitro. Considering the increased OSM expression in colonic biopsy specimens of patients with active IBD, OSM upregulation may modulate a barrier-protective host response in intestinal inflammation. Further in vivo studies are warranted to elucidate the exact role of OSM in intestinal inflammation and the potential of OSM as a drug target in IBD.

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.

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.

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.

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.

A novel role for interleukin-27 (IL-27) as mediator of intestinal epithelial barrier protection mediated via differential signal transducer and activator of transcription (STAT) protein signaling and induction of antibacterial and anti-inflammatory proteins.

The role of the Th17 cell inhibiting cytokine IL-27 in the pathogenesis of inflammatory bowel disease is contradictory. Its effects on the intestinal barrier have so far not been investigated, which was the aim of this study. We show that intestinal epithelial cells (IEC) express both IL-27 receptor subunits IL-27RA and gp130. The IL-27 receptor expression is up-regulated in intestinal inflammation and during bacterial infection. IL-27 activates ERK and p38 MAPKs as well as Akt, STAT1, STAT3, and STAT6 in IEC. IL-27 significantly enhances cell proliferation and IEC restitution. These functions of IL-27 are dependent on the activation of STAT3 and STAT6 signaling pathways. As analyzed by microarray, IL-27 modulates the expression of 428 target genes in IEC (316 up and 112 down; p<0.05). IL-27 as well as its main target genes are up-regulated in colonic tissue and IEC isolated from mice with dextran sulfate sodium (DSS)-induced colitis. The IL-27-induced expression of the anti-bacterial gene deleted in malignant brain tumor 1 (DMBT1) is mediated by p38 and STAT3 signaling, whereas the activation of the anti-inflammatory and anti-bacterial gene indoleamine 2,3-dioxygenase (IDO1) is dependent on STAT1 signal transduction. IL-27-induced indoleamine 2,3-dioxygenase enzymatic activity leads to growth inhibition of intestinal bacteria by causing local tryptophan depletion. For the first time, we characterize IL-27 as a mediator of intestinal epithelial barrier protection mediated via transcriptional activation of anti-inflammatory and antibacterial target genes.

PTGER4 expression-modulating polymorphisms in the 5p13.1 region predispose to Crohn's disease and affect NF-κB and XBP1 binding sites.

BACKGROUND: Genome-wide association studies identified a PTGER4 expression-modulating region on chromosome 5p13.1 as Crohn's disease (CD) susceptibility region. The study aim was to test this association in a large cohort of patients with inflammatory bowel disease (IBD) and to elucidate genotypic and phenotypic interactions with other IBD genes. METHODOLOGY/PRINCIPAL FINDINGS: A total of 7073 patients and controls were genotyped: 844 CD and 471 patients with ulcerative colitis and 1488 controls were analyzed for the single nucleotide polymorphisms (SNPs) rs4495224 and rs7720838 on chromosome 5p13.1. The study included two replication cohorts of North American (CD: n = 684; controls: n = 1440) and of German origin (CD: n = 1098; controls: n = 1048). Genotype-phenotype, epistasis and transcription factor binding analyses were performed. In the discovery cohort, an association of rs4495224 (p = 4.10×10⁻5; 0.76 [0.67-0.87]) and of rs7720838 (p = 6.91×10⁻4; 0.81 [0.71-0.91]) with susceptibility to CD was demonstrated. These associations were confirmed in both replication cohorts. In silico analysis predicted rs4495224 and rs7720838 as essential parts of binding sites for the transcription factors NF-κB and XBP1 with higher binding scores for carriers of the CD risk alleles, providing an explanation of how these SNPs might contribute to increased PTGER4 expression. There was no association of the PTGER4 SNPs with IBD phenotypes. Epistasis detected between 5p13.1 and ATG16L1 for CD susceptibility in the discovery cohort (p = 5.99×10⁻7 for rs7720838 and rs2241880) could not be replicated in both replication cohorts arguing against a major role of this gene-gene interaction in the susceptibility to CD. CONCLUSIONS/SIGNIFICANCE: We confirmed 5p13.1 as a major CD susceptibility locus and demonstrate by in silico analysis rs4495224 and rs7720838 as part of binding sites for NF-κB and XBP1. Further functional studies are necessary to confirm the results of our in silico analysis and to analyze if changes in PTGER4 expression modulate CD susceptibility.

Pregnane X receptor (PXR/NR1I2) gene haplotypes modulate susceptibility to inflammatory bowel disease.

BACKGROUND: The pregnane X receptor (PXR/NR1I2) is an important regulator of xenobiotic metabolism and intestinal integrity. However, there are controversial studies on the role of PXR/NR1I2 in inflammatory bowel disease (IBD). We therefore initiated the largest analysis to date on PXR/NR1I2 gene variants in IBD patients. METHODS: Genomic DNA from 2823 individuals of Caucasian origin including 859 patients with Crohn's disease (CD), 464 patients with ulcerative colitis (UC), and 1500 healthy, unrelated controls was analyzed for eight PXR/NR1I2 single nucleotide polymorphisms (SNPs) (rs12721602 (-25564), rs3814055 (-25385), rs1523128 (-24756), rs1523127 (-24381), rs45610735 = p.Gly36Arg (+106), rs6785049 (+7635), rs2276707 (+8055), and rs3814057 (+11156)). In addition, detailed haplotype and genotype-phenotype analyses were performed. RESULTS: The PXR/NR1I2 SNP rs2276707 was weakly associated with UC susceptibility (P = 0.01; odds ratio [OR] 1.27 [1.06-1.52]). None of the other PXR/NR1I2 SNPs were associated with UC or CD susceptibility. However, several rare PXR/NR1I2 haplotypes were highly associated with CD susceptibility. In CD, the strongest disease association was found for a haplotype consisting of the SNPs rs12721602-rs3814055-rs1523128-rs1523127-rs12721607-rs6785049-rs2276707-rs3814057 (omnibus P-value: 6.50 × 10(-15)) which was found in two separate cohorts (cohort I = discovery cohort: CD: n = 492, controls: n = 793; P = 4.51 × 10(-17); Bonferroni corrected: P = 1.27 × 10(-15); cohort II = replication cohort: CD: n = 367, controls: n = 707; P = 7.12 × 10(-4); P(corr) = 1.99 × 10(-2)). CONCLUSIONS: Several PXR/NR1I2 haplotypes contribute to CD susceptibility, suggesting a role for PXR in the IBD pathogenesis of a certain patient subcohort. Given the accumulating evidence for an important role of PXR in intestinal inflammation, further analyses are required to investigate the functional and pharmacogenetic implications of these PXR/NR1I2 gene variants in IBD.

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.