Carsten Büning

Genome-wide meta-analysis increases to 71 the number of confirmed Crohn's disease susceptibility loci

We undertook a meta-analysis of six Crohns disease genome-wide association studies (GWAS) comprising 6,333 affected individuals (cases) and 15,056 controls and followed up the top association signals in 15,694 cases, 14,026 controls and 414 parent-offspring trios. We identified 30 new susceptibility loci meeting genome-wide significance (P < 5 × 10−8). A series of in silico analyses highlighted particular genes within these loci and, together with manual curation, implicated functionally interesting candidate genes including SMAD3, ERAP2, IL10, IL2RA, TYK2, FUT2, DNMT3A, DENND1B, BACH2 and TAGAP. Combined with previously confirmed loci, these results identify 71 distinct loci with genome-wide significant evidence for association with Crohns disease.

Genetic basis for increased intestinal permeability in families with Crohn’s disease: role of CARD15 3020insC mutation?

Background and aim: A genetically impaired intestinal barrier function has long been suspected to be a predisposing factor for Crohn’s disease (CD). Recently, mutations of the capsase recruitment domain family, member 15 (CARD15) gene have been identified and associated with CD. We hypothesise that a CARD15 mutation may be associated with an impaired intestinal barrier. Methods: We studied 128 patients with quiescent CD, 129 first degree relatives (CD-R), 66 non-related household members (CD-NR), and 96 healthy controls. The three most common CARD15 polymorphisms (R702W, G908R, and 3020insC) were analysed and intestinal permeability was determined by the lactulose/mannitol ratio. Results: Intestinal permeability was significantly increased in CD and CD-R groups compared with CD-NR and controls. Values above the normal range were seen in 44% of CD and 26% of CD-R but only in 6% of CD-NR, and in none of the controls. A household community with CD patients, representing a common environment, was not associated with increased intestinal permeability in family members. However, 40% of CD first degree relatives carrying a CARD15 3020insC mutation and 75% (3/4) of those CD-R with combined 3020insC and R702W mutations had increased intestinal permeability compared with only 15% of wild-types, indicating a genetic influence on barrier function. R702W and G908R mutations were not associated with high permeability. Conclusions: In healthy first degree relatives, high mucosal permeability is associated with the presence of a CARD15 3020insC mutation. This indicates that genetic factors may be involved in impairment of intestinal barrier function in families with IBD.

Chymotrypsin C (CTRC) variants that diminish activity or secretion are associated with chronic pancreatitis.

Chronic pancreatitis is a persistent inflammatory disease of the pancreas, in which the digestive protease trypsin has a fundamental pathogenetic role. Here we have analyzed the gene encoding the trypsin-degrading enzyme chymotrypsin C (CTRC) in German subjects with idiopathic or hereditary chronic pancreatitis. Two alterations in this gene, p.R254W and p.K247_R254del, were significantly overrepresented in the pancreatitis group, being present in 30 of 901 (3.3%) affected individuals but only 21 of 2,804 (0.7%) controls (odds ratio (OR) = 4.6; confidence interval (CI) = 2.6–8.0; P = 1.3 × 10−7). A replication study identified these two variants in 10 of 348 (2.9%) individuals with alcoholic chronic pancreatitis but only 3 of 432 (0.7%) subjects with alcoholic liver disease (OR = 4.2; CI = 1.2–15.5; P = 0.02). CTRC variants were also found in 10 of 71 (14.1%) Indian subjects with tropical pancreatitis but only 1 of 84 (1.2%) healthy controls (OR = 13.6; CI = 1.7–109.2; P = 0.0028). Functional analysis of the CTRC variants showed impaired activity and/or reduced secretion. The results indicate that loss-of-function alterations in CTRC predispose to pancreatitis by diminishing its protective trypsin-degrading activity.

Mutations in the NOD2/CARD15 gene in Crohn's disease are associated with ileocecal resection and are a risk factor for reoperation

Background : Mutations within the NOD2/CARD15 gene have recently been shown to be associated with Crohns disease.

Malnutrition and impaired muscle strength in patients with Crohn's disease and ulcerative colitis in remission

OBJECTIVE This prospective, controlled, and multicentric study evaluated nutritional status, body composition, muscle strength, and quality of life in patients with inflammatory bowel disease in clinical remission. In addition, possible effects of gender, malnutrition, inflammation, and previous prednisolone therapy were investigated. METHODS Nutritional status (subjective global assessment [SGA], body mass index, albumin, trace elements), body composition (bioelectrical impedance analysis, anthropometry), handgrip strength, and quality of life were assessed in 94 patients with Crohns disease (CD; 61 female and 33 male, Crohns Disease Activity Index 71 +/- 47), 50 patients with ulcerative colitis (UC; 33 female and 17 male, Ulcerative Colitis Activity Index 3.1 +/- 1.5), and 61 healthy control subjects (41 female and 20 male) from centers in Berlin, Vienna, and Bari. For further analysis of body composition, 47 well-nourished patients with inflammatory bowel disease were pair-matched by body mass index, sex, and age to healthy controls. Data are presented as median (25th-75th percentile). RESULTS Most patients with inflammatory bowel disease (74%) were well nourished according to the SGA, body mass index, and serum albumin. However, body composition analysis demonstrated a decrease in body cell mass (BCM) in patients with CD (23.1 kg, 20.8-28.7, P = 0.021) and UC (22.6 kg, 21.0-28.0, P = 0.041) compared with controls (25.0 kg, 22.0-32.5). Handgrip strength correlated with BCM (r = 0.703, P = 0.001) and was decreased in patients with CD (32.8 kg, 26.0-41.1, P = 0.005) and UC (31.0 kg, 27.3-37.8, P = 0.001) compared with controls (36.0 kg, 31.0-52.0). The alterations were seen even in patients classified as well nourished. BCM was lower in patients with moderately increased serum C-reactive protein levels compared with patients with normal levels. CONCLUSION In CD and UC, selected micronutrient deficits and loss of BCM and muscle strength are frequent in remission and cannot be detected by standard malnutrition screening.

High-density genotyping study identifies four new susceptibility loci for atopic dermatitis.

Atopic dermatitis is a common inflammatory skin disease with a strong heritable component. Pathogenetic models consider keratinocyte differentiation defects and immune alterations as scaffolds, and recent data indicate a role for autoreactivity in at least a subgroup of patients. FLG (encoding filaggrin) has been identified as a major locus causing skin barrier deficiency. To better define risk variants and identify additional susceptibility loci, we densely genotyped 2,425 German individuals with atopic dermatitis (cases) and 5,449 controls using the Immunochip array followed by replication in 7,196 cases and 15,480 controls from Germany, Ireland, Japan and China. We identified four new susceptibility loci for atopic dermatitis and replicated previous associations. This brings the number of atopic dermatitis risk loci reported in individuals of European ancestry to 11. We estimate that these susceptibility loci together account for 14.4% of the heritability for atopic dermatitis.

Long-Term Effectiveness of Azathioprine in IBD Beyond 4 Years: A European Multicenter Study in 1176 Patients

In Crohn’s disease the optimal duration of azathioprine treatment is still controversial and for ulcerative colitis only limited data are available to support its efficacy. Charts of 1176 patients with IBD from 16 European centers were analyzed. Flare incidences and steroid dosages were assessed for the time before and during treatment and after discontinuation. Within the first 4 years, azathioprine suppressed flare incidence and steroid consumption in both diseases (P < 0.001). While in CD discontinuation after 3–4 years did not lead to reactivation, this was the case in UC. However, continuation beyond 4 years further improved clinical activity in CD and steroid requirement in both diseases (P < 0.001). Discontinuation of azathioprine may thus be considered after 3–4 years in CD patients in complete remission without steroid requirement. In all other CD patients and for UC patients in general, continuation seems beneficial. These results support a novel differential algorithm for long-term azathioprine therapy in IBD.

Association Between Variants of PRDM1 and NDP52 and Crohn's Disease, Based on Exome Sequencing and Functional Studies

BACKGROUND & AIMS Genome-wide association studies (GWAS) have identified 140 Crohns disease (CD) susceptibility loci. For most loci, the variants that cause disease are not known and the genes affected by these variants have not been identified. We aimed to identify variants that cause CD through detailed sequencing, genetic association, expression, and functional studies. METHODS We sequenced whole exomes of 42 unrelated subjects with CD and 5 healthy subjects (controls) and then filtered single nucleotide variants by incorporating association results from meta-analyses of CD GWAS and in silico mutation effect prediction algorithms. We then genotyped 9348 subjects with CD, 2868 subjects with ulcerative colitis, and 14,567 control subjects and associated variants analyzed in functional studies using materials from subjects and controls and in vitro model systems. RESULTS We identified rare missense mutations in PR domain-containing 1 (PRDM1) and associated these with CD. These mutations increased proliferation of T cells and secretion of cytokines on activation and increased expression of the adhesion molecule L-selectin. A common CD risk allele, identified in GWAS, correlated with reduced expression of PRDM1 in ileal biopsy specimens and peripheral blood mononuclear cells (combined P = 1.6 × 10(-8)). We identified an association between CD and a common missense variant, Val248Ala, in nuclear domain 10 protein 52 (NDP52) (P = 4.83 × 10(-9)). We found that this variant impairs the regulatory functions of NDP52 to inhibit nuclear factor κB activation of genes that regulate inflammation and affect the stability of proteins in Toll-like receptor pathways. CONCLUSIONS We have extended the results of GWAS and provide evidence that variants in PRDM1 and NDP52 determine susceptibility to CD. PRDM1 maps adjacent to a CD interval identified in GWAS and encodes a transcription factor expressed by T and B cells. NDP52 is an adaptor protein that functions in selective autophagy of intracellular bacteria and signaling molecules, supporting the role of autophagy in the pathogenesis of CD.

Circulating adipokines and the protective effects of hyperinsulinemia in inflammatory bowel disease.

OBJECTIVE Adipokines are fat-derived hormones and cytokines with immune-modulating and metabolic properties. Most of them are associated with insulin resistance. The aim of the present investigation was to evaluate circulating levels of adipokines and glucose homeostasis in patients with inflammatory bowel disease (IBD) and to evaluate possible associations with the course and characteristics of the disease. METHODS Serum leptin, resistin, visfatin, retinol-binding protein-4, adiponectin, glucose, insulin, and inflammatory parameters were analyzed in 93 patients with inactive IBD (49 with Crohns disease [CD], 44 with ulcerative colitis [UC]), 35 patients with active IBD (18 with CD, 17 with UC), and 37 age- and body mass index-matched healthy controls. Ninety-two patients were followed for 6 mo. RESULTS Leptin was similar in patients with IBD and controls, whereas resistin and visfatin were increased in patients with active disease but not in those in remission. In active and inactive disease, adiponectin was decreased (P < 0.001) and retinol-binding protein-4 was increased (P < 0.001) compared with controls. About 60% of patients with IBD showed increased levels of insulin, whereas serum glucose remained normal, resulting in increased homeostasis model assessment values in most patients. Hyperinsulinemia was associated with the decrease in adiponectin (r = -0.572, P < 0.001) and proved to be an independent protective factor for 6-mo maintenance of remission (P = 0.016). CONCLUSION IBD led to largely similar alterations in circulating adipokines and hyperinsulinemia in patients with CD and those with UC. The unexpected protective effect of hyperinsulinemia on relapse rate denotes the role of the metabolic-inflammatory response as a modulator in IBD.

Gender-stratified analysis of DLG5 R30Q in 4707 patients with Crohn disease and 4973 controls from 12 Caucasian cohorts

Background: DLG5 p.R30Q has been reported to be associated with Crohn disease (CD), but this association has not been replicated in most studies. A recent analysis of gender-stratified data from two case–control studies and two population cohorts found an association of DLG5 30Q with increased risk of CD in men but not in women and found differences between 30Q population frequencies for males and females. Male–female differences in population allele frequencies and male-specific risk could explain the difficulty in replicating the association with CD. Methods: DLG5 R30Q genotype data were collected for patients with CD and controls from 11 studies that did not include gender-stratified allele counts in their published reports and tested for male–female frequency differences in controls and for case–control frequency differences in men and in women. Results: The data showed no male–female allele frequency differences in controls. An exact conditional test gave marginal evidence that 30Q is associated with decreased risk of CD in women (p = 0.049, OR = 0.87, 95% CI 0.77 to 1.00). There was also a trend towards reduced 30Q frequencies in male patients with CD compared with male controls, but this was not significant at the 0.05 level (p = 0.058, OR = 0.87, 95% CI 0.74 to 1.01). When data from this study were combined with previously published, gender-stratified data, the 30Q allele was found to be associated with decreased risk of CD in women (p = 0.010, OR = 0.86, 95% CI 0.76 to 0.97), but not in men. Conclusion: DLG5 30Q is associated with a small reduction in risk of CD in women.