Marie Pierik

Deficient host-bacteria interactions in inflammatory bowel disease? The toll-like receptor (TLR)-4 Asp299gly polymorphism is associated with Crohn’s disease and ulcerative colitis

Background and aims: Elicitation of an innate immune response to bacterial products is mediated through pattern recognition receptors (PRRs) such as the toll-like receptors (TLRs) and the NODs. The recently characterised Asp299Gly polymorphism in the lipopolysaccharide (LPS) receptor TLR4 is associated with impaired LPS signalling and increased susceptibility to Gram negative infections. We sought to determine whether this polymorphism was associated with Crohn’s disease (CD) and/or ulcerative colitis (UC). Methods: Allele frequencies of the TLR4 Asp299Gly polymorphism and the three NOD2/CARD15 polymorphisms (Arg702Trp, Gly908Arg, and Leu1007fsinsC) were assessed in two independent cohorts of CD patients (cohort 1, n = 334; cohort 2, n = 114), in 163 UC patients, and in 140 controls. A transmission disequilibrium test (TDT) was then performed on 318 inflammatory bowel disease (IBD) trios. Results: The allele frequency of the TLR4 Asp299Gly polymorphism was significantly higher in CD (cohort 1: 11% v 5%, odds ratio (OR) 2.31 (95% confidence interval (CI) 1.28–4.17), p = 0.004; and cohort 2: 12% v 5%, OR 2.45 (95% CI 1.24–4.81), p = 0.007) and UC patients (10% v 5%, OR 2.05 (95% CI 1.07–3.93), p = 0.027) compared with the control population. A TDT on 318 IBD trios demonstrated preferential transmission of the TLR4 Asp299Gly polymorphism from heterozygous parents to affected children (T/U: 68/34, p = 0.01). Carrying polymorphisms in both TLR4 and NOD2 was associated with a genotype relative risk (RR) of 4.7 compared with a RR of 2.6 and 2.5 for TLR4 and NOD2 variants separately. Conclusion: We have reported on a novel association of the TLR4 Asp299Gly polymorphism with both CD and UC. This finding further supports the genetic influence of PRRs in triggering IBD.

New serological markers in inflammatory bowel disease are associated with complicated disease behaviour

Background and aims: Several antibodies have been associated with Crohn’s disease and are associated with distinct clinical phenotypes. The aim of this study was to determine whether a panel of new antibodies against bacterial peptides and glycans could help in differentiating inflammatory bowel disease (IBD), and whether they were associated with particular clinical manifestations. Methods: Antibodies against a mannan epitope of Saccharomyces cerevisiae (gASCA), laminaribioside (ALCA), chitobioside (ACCA), mannobioside (AMCA), outer membrane porins (Omp) and the atypical perinuclear antineutrophilic cytoplasmic antibody (pANCA) were tested in serum samples of 1225 IBD patients, 200 healthy controls and 113 patients with non-IBD gastrointestinal inflammation. Antibody responses were correlated with the type of disease and clinical characteristics. Results: 76% of Crohn’s disease patients had at least one of the tested antibodies. For differentiation between Crohn’s disease and ulcerative colitis, the combination of gASCA and pANCA was most accurate. For differentiation between IBD, healthy controls and non-IBD gastrointestinal inflammation, the combination of gASCA, pANCA and ALCA had the best accuracy. Increasing amounts and levels of antibody responses against gASCA, ALCA, ACCA, AMCA and Omp were associated with more complicated disease behaviour (44.7% versus 53.6% versus 71.1% versus 82.0%, p < 0.001), and a higher frequency of Crohn’s disease-related abdominal surgery (38.5% versus 48.8% versus 60.7% versus 75.4%, p < 0.001). Conclusions: Using this new panel of serological markers, the number and magnitude of immune responses to different microbial antigens were shown to be associated with the severity of the disease. With regard to the predictive role of serological markers, further prospective longitudinal studies are necessary.

Toll‐like receptor‐1, ‐2, and ‐6 polymorphisms influence disease extension in inflammatory bowel diseases

Background: Evidence that a deficient innate immune response toward the bacterial flora of the gut plays a role in the pathogenesis of inflammatory bowel disease (IBD) is growing. This is underscored by the finding of the association between CARD15 variants and Crohns disease (CD) and D299G in Toll‐like receptor (TLR) 4 and IBD. Our aims were to study nonsynonymous polymorphisms in other TLR genes in IBD. Methods: Thirty‐five single nucleotide polymorphisms (SNP) in TLR1‐10 were identified from public databases. 284 IBD parent‐child trios and a second independent cohort of 285 IBD patients and 191 healthy controls were genotyped with polymerase chain reaction‐restriction fragment length polymorphisms. Patients were pooled for genotype‐phenotype analyses. Results: Although none of the SNPs was involved in disease susceptibility, a number of variants influenced the disease phenotype. A positive association between TLR1 R80T and pancolitis in UC (P = .045, OR [95% CI] 2.844 [1.026‐7.844]) was found. The TLR2 R753G SNP was also associated with pancolitis (P = .027, OR [95% CI] 4.741 [1.197‐18.773]). The relative risks for heterozygous patients to develop pancolitis were 5.8 and 3.3 for R80T and R753G, respectively. There was a negative association between TLR6 S249P and ulcerative colitis with proctitis only (P = .026, OR [95% CI] 0.223 [0.096‐0.705]). In CD, we found a negative association between ileal disease involvement and TLR1 S602I (P = .03, OR [95% CI] 0.522 [0.286‐0.950]). Conclusion: TLR2 and its cofactors TLR1 and TLR6 are involved in the initial immune response to bacteria by recognizing peptidoglycan. An association between nonsynonymous variants in the TLR1, ‐2, and ‐6 genes and extensive colonic disease in UC and CD was found. Our findings further highlight the role of an abnormal innate immune response in the pathogenesis of IBD.

The impact of major depressive disorder on the short- and long-term outcome of Crohn's disease treatment with infliximab

Background:  Major depressive disorder is the most common psychiatric diagnosis in Crohns disease. In other chronic diseases, evidence suggests that depression influences the course of the disease. Strong evidence of such a mediating role of major depressive disorder in Crohns disease has never been found.

Polymorphisms in apoptosis genes predict response to infliximab therapy in luminal and fistulizing Crohn's disease

Background : Infliximab treatment is effective in 70–80% of patients with refractory luminal and fistulizing Crohns disease. The effect of infliximab is ascribed to induction of apoptosis.

High intra-uterine exposure to infliximab following maternal anti-TNF treatment during pregnancy

Aliment Pharmacol Ther 2011; 33: 1053–1058

Tumour necrosis factor-alpha receptor 1 and 2 polymorphisms in inflammatory bowel disease and their association with response to infliximab.

Background : The role of tumour necrosis factor‐α in the pathogenesis of inflammatory bowel disorders is well‐known and is underscored by the effectiveness of antitumour necrosis factor‐α treatment. Tumour necrosis factor‐α exerts its effect by binding TNFR1 and TNFR2, which genes map to inflammatory bowel disorders susceptibility loci.

Fatigue and health-related quality of life in inflammatory bowel disease: results from a population-based study in the Netherlands: the IBD-South Limburg cohort.

Background: The importance of fatigue in chronic disease has been increasingly recognized; however, little is known about fatigue in inflammatory bowel disease (IBD). The aim of the present study was to investigate the prevalence and severity of fatigue and the impact on health‐related quality of life (HRQoL) in patients included in a population‐based IBD cohort in the Netherlands. Methods: IBD patients, diagnosed between January 1st, 1991, and January 1st, 2003, were followed up for a median of 7.1 years. They completed a questionnaire, which included a disease activity score, the Multidimensional Fatigue Inventory (MFI‐20), the Inflammatory Bowel Disease Questionnaire (IBDQ), and the Short Form health survey (SF‐36). Hemoglobin levels were recorded. Results: Data were available in 304 Crohns disease (CD), 368 ulcerative colitis (UC), and 35 indeterminate colitis (IC) patients. During quiescent disease, the prevalence of fatigue was nearly 40%. MFI‐20 and HRQoL scores were significantly worse in IBD patients having active disease. In a multivariate analysis, disease activity was positively related with the level of fatigue in both CD and UC. In UC, anemia influenced the general fatigue score independently of disease activity. Disease activity as well as fatigue were independently associated with an impaired IBDQ. Conclusions: In IBD, even in remission, fatigue is an important feature. Both in CD and in UC, fatigue determined HRQoL independently of disease activity or anemia. This implies that in IBD patients physicians need to be aware of fatigue in order to better understand its impact and to improve the HRQoL. (Inflamm Bowel Dis 2010)

Mutations in pattern recognition receptor genes modulate seroreactivity to microbial antigens in patients with inflammatory bowel disease

Background and aims: A number of antibodies against microbial epitopes or self-antigens have been associated with Crohn’s disease. The development of antibodies reflects a loss of tolerance to intestinal bacteria that underlies Crohn’s disease, resulting in an exaggerated adaptive immune response to these bacteria. It was hypothesised that the development of antimicrobial antibodies is influenced by the presence of genetic variants in pattern recognition receptor genes. The aim of this study was therefore to investigate the influence of mutations in these innate immune receptor genes (nucleotide oligomerisation domain (NOD) 2/caspase recruitment domain (CARD) 15, NOD1/CARD4, TUCAN/CARDINAL/CARD8, Toll-like receptor (TLR) 4, TLR2, TLR1 and TLR6) on the development of antimicrobial and antiglycan antibodies in inflammatory bowel disease (IBD). Materials and methods: A cohort of 1163 unrelated patients with IBD (874 Crohn’s disease, 259 ulcerative colitis, 30 indeterminate colitis) and 312 controls were analysed for anti-Saccharomyces cerevisiae antibodies (gASCA) IgG, anti-laminaribioside antibodies (ALCA) IgG, anti-chitobioside antibodies (ACCA) IgA, anti-mannobioside antibodies (AMCA) IgG and outer membrane porin (Omp) IgA and were genotyped for variants in NOD2/CARD15, TUCAN/CARDINAL/CARD8, NOD1/CARD4, TLR4, TLR1, TLR2 and TLR6. Results: When compared with Crohn’s disease patients without CARD15 mutations, the presence of at least one CARD15 variant in Crohn’s disease patients more frequently led to gASCA positivity (66.1% versus 51.5%, p < 0.0001) and ALCA positivity (43.3% versus 34.9%, p  =  0.018) and higher gASCA titers (85.7 versus 51.8 ELISA units, p < 0.0001), independent of ileal involvement. A gene dosage effect, with increasing gASCA and ALCA positivity for patients carrying none, one and two CARD15 variants, respectively, was seen for both markers. Similarly, Crohn’s disease patients carrying NOD1/CARD4 indel had a higher prevalence of gASCA antibodies than wild-type patients (63.8% versus 55.2%, p  =  0.014), also with a gene dosage effect. An opposite effect was observed for the TLR4 D299G and TLR2 P631H variants, with a lower prevalence of ACCA antibodies (23.4% versus 35%, p  =  0.013) and Omp antibodies (20.5% versus 34.6%, p  =  0.009), respectively. Conclusion: Variants in innate immune receptor genes were found to influence antibody formation against microbial epitopes. In this respect, it is intriguing that an opposite effect of CARD15 and TLR4 variants was observed. These findings may contribute to an understanding of the aetiology of the seroreactivity observed in IBD.

Genome wide scan in a Flemish inflammatory bowel disease population: support for the IBD4 locus, population heterogeneity, and epistasis

Background and aims: Genome wide scans in inflammatory bowel disease (IBD) have indicated various susceptibility regions with replication of 16cen (IBD1), 12q (IBD2), 6p (IBD3), 14q11 (IBD4), and 3p21. As no linkage was previously found on IBD regions 3, 7, 12, and 16 in Flemish IBD families, a genome wide scan was performed to detect other susceptibility regions in this population. Methods: A cohort of 149 IBD affected relative pairs, all recruited from the Northern Flemish part of Belgium, were genotyped using microsatellite markers at 12 cM intervals, and analysed by Genehunter non-parametric linkage software. All families were further genotyped for the three main Crohn’s disease associated variants in the NOD2/CARD15 gene. Results: Nominal evidence for linkage was observed on chromosomes 1 (D1S197: multipoint non-parametric linkage (NPL) score 2.57, p = 0.004; and at D1S305-D1S252: NPL 2.97, p = 0.001), 4q (D4S406: NPL 1.95, p = 0.03), 6q16 (D6S314: NPL 2.44, p = 0.007), 10p12 (D10S197: NPL 2.05, p = 0.02), 11q22 (D11S35-D11S927: NPL 1.95, p = 0.02) 14q11-12 (D14S80: NPL 2.41, p = 0.008), 20p12 (D20S192: NPL 2.7, p = 0.003), and Xq (DXS990: NPL 1.70, p = 0.04). A total of 51.4% of patients carried at least one NOD2/CARD15 variant. Furthermore, epistasis was observed between susceptibility regions 6q/10p and 20p/10p. Conclusion: Genome scanning in a Flemish IBD population found nominal evidence for linkage on 1p, 4q, 10p12, and 14q11, overlapping with other genome scan results, with linkage on 14q11-12 supporting the IBD4 locus. The results further show that epistasis is contributing to the complex model of IBD and indicate that population heterogeneity is not to be underestimated. Finally, NOD2/CARD15 is clearly implicated in the Flemish IBD population.