Crohn's Disease and Early Exposure to Domestic Refrigeration

Environmental risk factors playing a causative role in Crohn's Disease (CD) remain largely unknown. Recently, it has been suggested that refrigerated food could be involved in disease development. We thus conducted a pilot case control study to explore the association of CD with the exposure to domestic refrigeration in childhood.Using a standard questionnaire we interviewed 199 CD cases and 207 age-matched patients with irritable bowel syndrome (IBS) as controls. Cases and controls were followed by the same gastroenterologists of tertiary referral clinics in Tehran, Iran. The questionnaire focused on the date of the first acquisition of home refrigerator and freezer. Data were analysed by a multivariate logistic model. The current age was in average 34 years in CD cases and the percentage of females in the case and control groups were respectively 48.3% and 63.7%. Patients were exposed earlier than controls to the refrigerator (X2 = 9.9, df = 3, P = 0.04) and refrigerator exposure at birth was found to be a risk factor for CD (OR = 2.08 (95% CI: 1.01-4.29), P = 0.05). Comparable results were obtained looking for the exposure to freezer at home. Finally, among the other recorded items reflecting the hygiene and comfort at home, we also found personal television, car and washing machine associated with CD.This study supports the opinion that CD is associated with exposure to domestic refrigeration, among other household factors, during childhood

On the genetic involvement of apoptosis-related genes in Crohn's disease as revealed by an extended association screen using 245 markers: no evidence for new predisposing factors

Crohn's disease (CD) presents as an inflammatory barrier disease with characteristic destructive processes in the intestinal wall. Although the pathomechanisms of CD are still not exactly understood, there is evidence that, in addition to e.g. bacterial colonisation, genetic predisposition contributes to the development of CD. In order to search for predisposing genetic factors we scrutinised 245 microsatellite markers in a population-based linkage mapping study. These microsatellites cover gene loci the encoded protein of which take part in the regulation of apoptosis and (innate) immune processes. Respective loci contribute to the activation/suppression of apoptosis, are involved in signal transduction and cell cycle regulators or they belong to the tumor necrosis factor superfamily, caspase related genes or the BCL2 family. Furthermore, several cytokines as well as chemokines were included. The approach is based on three steps: analyzing pooled DNAs of patients and controls, verification of significantly differing microsatellite markers by genotyping individual DNA samples and, finally, additional reinvestigation of the respective gene in the region covered by the associated microsatellite by analysing single-nucleotide polymorphisms (SNPs). Using this step-wise process we were unable to demonstrate evidence for genetic predisposition of the chosen apoptosis- and immunity-related genes with respect to susceptibility for CD

Frequency of single nucleotide polymorphisms in NOD1 gene of ulcerative colitis patients: a case-control study in the Indian population

<p>Abstract</p> <p>Background</p> <p>Epidemiological studies have provided enough evidence that genetic factors have an important role in determining susceptibility to IBD. The most significant finding in the IBD research has been identification of mutations in the gene that encodes Nod2 (nucleotide-binding oligomerization domain 2) protein in a subgroup of patients with Crohn's disease. However, a very similar gene encoding Nod1 protein still has not been well documented for its association with Ulcerative colitis patients. Detection of polymorphism in <it>NOD1 </it>gene using SNP analysis has been attempted in the present study. We evaluated frequency and significance of mutations present in the nucleotide-binding domain (NBD) of <it>NOD1 </it>gene in context to Indian population.</p> <p>Methods</p> <p>A total of 95 patients with ulcerative colitis and 102 controls enrolled in the Gastroenterology department of All India Institute of Medical Sciences, New Delhi were screened for SNPs by DHPLC and RFLP techniques. Exon 6 locus in the NBD domain of <it>NOD1 </it>gene was amplified and sequenced. Genotype and allele frequencies of the patients and controls were calculated by the Pearson's χ²test, Fisher's exact test and ANOVA with Bonferroni's correction using SPSS software version 12.</p> <p>Results</p> <p>We have demonstrated DHPLC screening technique to show the presence of SNPs in Exon 6 locus of NBD domain of <it>NOD1 </it>gene. The DHPLC analysis has proven suitable for rapid detection of base pair changes. The data was validated by sequencing of clones and subsequently by RFLP analysis. Analyses of SNP data revealed 3 significant mutations (W219R, <it>p </it>= 0.002; L349P, <it>p </it>= 0.002 and L370R, <it>p </it>= 0.039) out of 5 in the Exon 6 locus of NBD domain of the gene that encompasses ATP and Mg²⁺binding sites. No significant association was observed within different sub phenotypes.</p> <p>Conclusion</p> <p>We propose that the location of mutations in the Exon 6 spanning the ATP and Mg²⁺binding site of NBD in <it>NOD1 </it>gene may affect the process of oligomerization and subsequent function of the LRR domain. Further studies are been conducted at the protein level to prove this possibility.</p

Direct Bacterial Killing In Vitro by Recombinant Nod2 Is Compromised by Crohn's Disease-Associated Mutations

Background: A homeostatic relationship with the intestinal microflora is increasingly appreciated as essential for human health and wellbeing. Mutations in the leucine-rich repeat (LRR) domain of Nod2, a bacterial recognition protein, are associated with development of the inflammatory bowel disorder, Crohn’s disease. We investigated the molecular mechanisms underlying disruption of intestinal symbiosis in patients carrying Nod2 mutations. Methodology/Principal Findings: In this study, using purified recombinant LRR domains, we demonstrate that Nod2 is a direct antimicrobial agent and this activity is generally deficient in proteins carrying Crohn’s-associated mutations. Wildtype, but not Crohn’s-associated, Nod2 LRR domains directly interacted with bacteria in vitro, altered their metabolism and disrupted the integrity of the plasma membrane. Antibiotic activity was also expressed by the LRR domains of Nod1 and other pattern recognition receptors suggesting that the LRR domain is a conserved anti-microbial motif supporting innate cellular immunity. Conclusions/Significance: The lack of anti-bacterial activity demonstrated with Crohn’s-associated Nod2 mutations in vitro, supports the hypothesis that a deficiency in direct bacterial killing contributes to the association of Nod2 polymorphism

Genetic Loci Involved in Antibody Response to Mycobacterium avium ssp. paratuberculosis in Cattle

Background: Mycobacterium avium subsp. paratuberculosis (MAP) causes chronic enteritis in a wide range of animal species. In cattle, MAP causes a chronic disease called Johne's disease, or paratuberculosis, that is not treatable and the efficacy of vaccine control is controversial. The clinical phase of the disease is characterised by diarrhoea, weight loss, drop in milk production and eventually death. Susceptibility to MAP infection is heritable with heritability estimates ranging from 0.06 to 0.10. There have been several studies over the last few years that have identified genetic loci putatively associated with MAP susceptibility, however, with the availability of genome-wide high density SNP maker panels it is now possible to carry out association studies that have higher precision. Methodology/Principal Findings: The objective of the current study was to localize genes having an impact on Johne's disease susceptibility using the latest bovine genome information and a high density SNP panel (Illumina BovineSNP50 BeadChip) to perform a case/control, genome-wide association analysis. Samples from MAP case and negative controls were selected from field samples collected in 2007 and 2008 in the province of Lombardy, Italy. Cases were defined as animals serologically positive for MAP by ELISA. In total 966 samples were genotyped: 483 MAP ELISA positive and 483 ELISA negative. Samples were selected randomly among those collected from 119 farms which had at least one positive animal. Conclusion/Significance: The analysis of the genotype data identified several chromosomal regions associated with disease status: a region on chromosome 12 with high significance (P<5 710-6), while regions on chromosome 9, 11, and 12 had moderate significance (P<5 710-5). These results provide evidence for genetic loci involved in the humoral response to MAP. Knowledge of genetic variations related to susceptibility will facilitate the incorporation of this information into breeding programmes for the improvement of health status