Influence of a nucleotide oligomerization domain 1 (NOD1) polymorphism and NOD2 mutant alleles on Crohn's disease phenotype

Biomarkers for the Prediction and Diagnosis of Fibrostenosing Crohn's Disease: A Systematic Review

BACKGROUND AND AIMS

Intestinal strictures are a common complication of Crohn's disease (CD). Biomarkers of intestinal strictures would assist in their prediction, diagnosis, and monitoring. Herein we provide a comprehensive systematic review of studies assessing biomarkers that may predict or diagnose CD-associated strictures.

METHODS

We performed a systematic review of PubMed, EMBASE, ISI Web of Science, Cochrane Library, and Scopus to identify citations pertaining to biomarkers of intestinal fibrosis through July 6, 2020, that used a reference standard of full-thickness histopathology or cross-sectional imaging or endoscopy. Studies were categorized based on the type of biomarker they evaluated (serum, genetic, histopathologic, or fecal).

RESULTS

Thirty-five distinct biomarkers from 3 major groups were identified: serum (20 markers), genetic (9 markers), and histopathology (6 markers). Promising markers include cartilage oligomeric matrix protein, hepatocyte growth factor activator, and lower levels of microRNA-19-3p (area under the curves were 0.805, 0.738, and 0.67, respectively), and multiple anti-flagellin antibodies (A4-Fla2 [odds ratio, 3.41], anti Fla-X [odds ratio, 2.95], and anti-CBir1 [multiple]). Substantial heterogeneity was observed and none of the markers had undergone formal validation. Specific limitations to acceptance of these markers included failure to use a standardized definition of stricturing disease, lack of specificity, and insufficient relevance to the pathogenesis of intestinal strictures or incomplete knowledge regarding their operating properties.

CONCLUSIONS

There is a lack of well-defined studies on biomarkers of intestinal stricture. Development of reliable and accurate biomarkers of stricture is a research priority. Biomarkers can support the clinical management of CD patients and aid in the stratification and monitoring of patients during clinical trials of future antifibrotic drug candidates.

Genetic association analysis of CLEC5A and CLEC7A gene single-nucleotide polymorphisms and Crohn’s disease

BACKGROUND

Crohn’s disease (CD) is characterized by a multifactorial etiology and a significant impact of genetic traits. While NOD2 mutations represent well established risk factors of CD, the role of other genes is incompletely understood.

AIM

To challenge the hypothesis that single nucleotide polymorphisms (SNPs) in the genes CLEC5A and CLEC7A, two members of the C-type lectin domain family of pattern recognition receptors, may be associated with CD.

METHODS

SNPs in CLEC5A, CLEC7A and the known CD risk gene NOD2 were studied using real time PCR-based SNP assays. Therefore, DNA samples from 175 patients and 157 healthy donors were employed. Genotyping data were correlated with clinical characteristics of the patients and the results of gene expression data analyses.

RESULTS

In accordance with previous studies, rs2066844 and rs2066847 in NOD2 were found to be significantly associated with CD (allelic P values = 0.0368 and 0.0474, respectively). Intriguingly, for genotype AA of rs1285933 in CLEC5A, a potential association with CD (recessive P = 0.0523; odds ratio = 1.90) was observed. There were no associations between CD and SNPs rs2078178 and rs16910631 in CLEC7A. Variants of rs1285933 had no impact on CLEC5A gene expression. In contrast, genotype-dependent differences of CXCL5 expression in peripheral blood mononuclear cells were observed. There is no statistical interaction between the tested SNPs of NOD2 and CLEC5A, suggesting of a novel pathway contributing to the disease.

CONCLUSION

Our data encourage enlarged follow-up studies to further address an association of SNP rs1285933 in CLEC5A with CD. The C-type lectin domain family member also deserves attention regarding a potential role in the pathophysiology of CD.

Mutations in the NOD2 gene are associated with a specific phenotype and lower anti-tumor necrosis factor trough levels in Crohn's disease

OBJECTIVE

Nucleotide-binding oligomerization domain-containing protein 2 (NOD2) gene mutations are known to be an important risk factor in the pathogenesis of Crohn's disease (CD). Specific disease phenotypes are associated with the presence of NOD2 gene mutation. One treatment option is to use an anti-tumor necrosis factor (TNF)-α agent. Therapeutic drug monitoring (TDM) is usually performed in cases of a loss of response. Our aim was to explore whether NOD2 gene mutations have an effect on the disease phenotype, vitamin D levels, and on TDM in CD patients.

METHODS

This was a retrospective genotype-phenotype association study on NOD2 gene mutations in 161 patients with CD.

RESULTS

Altogether 55 (34.2%) patients carried at least one mutant allele of NOD2. NOD2 gene mutations were associated with ileocecal disease, ileocecal resection, stricturing and perianal disease, and patients with NOD2 gene mutation had significantly less frequent colonic disease and received an ostomy less frequently. TDM in patients with NOD2 gene mutation showed more frequent anti-TNF trough levels in the subtherapeutic range and lower anti-TNF trough levels than in NOD2 wild-type (WT) patients.

CONCLUSIONS

CD patients with NOD2 gene mutation have a specific clinical phenotype and they may require higher doses of anti-TNF agents to achieve sufficient anti-TNF trough levels. They may therefore benefit from a proactive TDM than a reactive approach. This could be another step in the direction of personalized medicine.

Relation of body mass index to risk of developing inflammatory bowel disease amongst women in the Danish National Birth Cohort

BACKGROUND

Crohn's disease (CD) has traditionally been associated with weight loss and low BMI, yet paradoxically obesity has recently been suggested as a risk factor for CD, but not for ulcerative colitis (UC). We therefore hypothesized that the relation between BMI and CD is U shaped.

AIM

To conduct a large population-based prospective cohort study of BMI and later risk of IBD, taking age at IBD diagnosis into account.

METHODS

A cohort of 74,512 women from the Danish National Birth Cohort, with BMI measured pre-pregnancy and 18 months after delivery, was followed for 1,022,250 person-years for development of IBD, according to the Danish National Patient Register. Associations were tested by Cox regression.

RESULTS

Overweight subjects (25≤BMI<30 kg/m2) had the lowest risk of CD, whereas obesity (BMI≥30kg/m2) increased the risk of CD at all ages, and low BMI (BMI<18.5kg/m2) associated with CD diagnosed at age 18-<40 years. Hence, using normal weight subjects as the reference, adjusted HRs for risk of developing CD (at age 18-<40 years) were 1.8(95%CI, 0.9-3.7) for underweight, 0.6(0.3-1.2) for overweight, and 1.5(0.8-2.7) for obese individuals (pre-pregnancy BMI). HRs were greater for BMI determined 18 months after delivery. Splines for CD risk according to waist:height ratio confirmed a U-shaped relationship with CD occurring <40 years, and a linear relationship with CD diagnosed at age 40+. There was no relationship between BMI and risk of UC.

CONCLUSION

For the first time, we demonstrate that both high BMI and low BMI are risk factors for CD. Underweight may be a pre-clinical manifestation of disease being present many years before onset with obesity being a true risk factor. This raises the question as to whether there may be two distinct forms of CD.

Effects of genetic variations in the genes encoding NOD1 and NOD2 on type 2 diabetes mellitus and insulin resistance

WHAT IS KNOWN AND OBJECTIVE

Nucleotide-binding oligomerization domain (NOD) 1 and NOD 2 are members of the NOD-like receptor (NLR) family and contain a caspase recruitment domain. NLRs are located in the cytosol, bind bacterial and viral ligands and play a key role in the realization of innate and adaptive immune response, inflammation, apoptosis and reactive oxygen species generation. Insulin resistance (IR) is a leading cause of type 2 diabetes mellitus (T2DM) and associated with obesity, inflammation and pro-inflammatory responses. NOD1 and NOD2 gene variants may affect the risk of chronic inflammation, insulin resistance and T2DM by shifting the balance between pro- and anti-inflammatory cytokines. The aim of our study was to determine whether the NOD1/2 gene variants might contribute to the risk of T2DM and IR.

METHODS

The rs5743336 variant of NOD1 and rs2066847 variant of NOD2 were analysed by PCR-RFLP analysis in 200 subjects (T2DM: n = 100; healthy controls: n = 100) of Turkish origin. PCR products were digested with the AvaI and ApaI restriction enzymes. For the NOD1 site, the presence of the G allele was indicated by cleavage of the 379 bp amplified PCR product that yielded 209-bp and 170-bp fragments. For the NOD2 site, 151-bp PCR products were cleaved and yielded 130-bp and 21-bp fragments when the WT-insC mutation was present. Comparisons of the genotypes between controls and patients were performed by chi-square tests.

RESULTS AND DISCUSSION

The genotypes of the rs5743336 variant of NOD1 and the rs2066847 variant of NOD2 are presented, and no significant differences were observed in the genotype frequencies of the NOD1 and NOD2 variants between the healthy controls and T2DM patients (P > 0·05). According to our preliminary data, NOD1/2 gene variants are not linked with T2DM and IR.

WHAT IS NEW AND CONCLUSION

This study is the first to look for possible association of the genotype frequencies of NOD1 and NOD2 genes with T2DM and IR. The significant finding of this report is that the rs5743336 and rs2066847 variations in the NOD1/2 gene are not associated with T2DM and IR risk in patients of Turkish origin.

Association of NOD1 and NOD2 polymorphisms with Guillain-Barré syndrome in Northern Indian population

BACKGROUND

Nucleotide oligomerization domain (NOD) proteins are cytosolic pattern recognition receptors that respond to bacterial substrate and induce NF-κB activation in host. Association of NOD polymorphisms have been studied in many autoimmune disorders, however its role in Guillain-Barré syndrome (GBS) remains unknown. We have investigated NOD1 Glu266Lys and NOD2 (Arg702Trp and Gly908Arg) gene polymorphisms among patients with GBS.

MATERIALS AND METHOD

Polymorphisms in NOD-1 (Glu266Lys) and NOD-2 (Arg702Trp and Gly908Arg) genes were studied using polymerase chain reaction-restriction fragment length polymorphism in 105 patients with GBS and 100 healthy controls.

RESULTS

Homozygous genotype (Lys/Lys) of NOD1 was significantly associated with GBS (p=0.013); and its subtypes viz. acute motor axonal neuropathy (AMAN) and acute inflammatory demyelinating polyneuropathy (AIDP) (p=0.008 and p=0.024 respectively) than controls. In NOD2 (Arg702Trp and Gly908Arg) polymorphisms, only heterozygous genotype (Arg/Trp and Gly/Arg) showed significant association with GBS (p=0.001 and p=0.01 respectively); subtypes AMAN, acute motor-sensory axonal neuropathy (AMSAN) and AIDP showed association with heterozygote Arg702Trp (p=0.001; p=0.029 and p=0.001 respectively) whereas only AIDP was associated with heterozygote genotype Gly908Arg (p=0.003).

CONCLUSION

NOD1 (Glu266Lys) and NOD2 (Arg702Trp and Gly908Arg) polymorphisms were associated with an increased susceptibility to GBS. These polymorphisms could be genetic marker to GBS susceptibility.

Increasing incidence of pediatric inflammatory bowel disease in Spain (1996-2009): the SPIRIT Registry

BACKGROUND

Although pediatric inflammatory bowel disease (IBD) diagnosis has increased in the last decades in Spain, there are no consistent epidemiologic data. Our aim was to describe the changing pattern of pediatric IBD incidence in Spain in the last 14 years.

METHODS

A retrospective survey of patients diagnosed below 18 years of age in the period 1996-2009 was performed. Patients' data were obtained from the hospitals' databases. To avoid reduced accrual of cases diagnosed by adult physicians, adult IBD units in referral centers were invited to participate. Seventy-eight centers participated in our survey. Rates of incidence were calculated using age-stratified population-based epidemiologic data. Incidence rates were compared for the last 14 years (1996-2009).

RESULTS

In total, data from 2107 patients were obtained: 1,165 Crohn's disease (CD, 55.3%), 788 ulcerative colitis (UC, 37.4%), and 154 IBD unclassified. The sex distribution was 56.4% male, with higher predominance for CD (59.3%) as compared to UC (52.8%) and IBD unclassified (53.2%) (P = 0.012). The median age at diagnosis was 12.3 years (p25-75 9.7-14.6) with significant differences between diseases. IBD incidence increased from 0.97 to 2.8/100,000 inhabitants <18 years/year in the study period. Although this increase is more evident for CD (from 0.53 to 1.7), UC has also risen considerably (0.39 to 0.88).

CONCLUSIONS

This is the first attempt to calculate the current incidence of pediatric IBD in Spain. A significant increase of incidence rates in the study period was observed. In the last 14 years pediatric IBD incidence has almost tripled, with a more important CD increase.

Gene polymorphisms of NOD1 and interleukin-8 influence the susceptibility to erosive esophagitis in Helicobacter pylori infected Japanese population

Helicobacter pylori (H. pylori) infection generally protects patients from erosive esophagitis through reduction of acid production due to gastric mucosal atrophy. However, there are H. pylori infected patients who still have erosive esophagitis. The reason for this discrepancy remains unclear. We have previously reported that polymorphisms in IL-8 promoter region influence the susceptibility of H. pylori related diseases. On the other hand, nucleotide-binding oligomerization domain 1 (NOD1) is known to play an important role in H. pylori infection. Hence, we hypothesized polymorphisms of these two molecules in H. pylori infected patients may influence the susceptibility to erosive esophagitis. Genomic DNA was extracted from 312 H. pylori infected Japanese, consisting of 110 patients with erosive esophagitis and 202 healthy controls. ND1+32656 T/GG and IL-8-251 A/T polymorphisms were genotyped by direct sequencing. ND1+32656 GG allele and IL-8-251 T/T allele increased the risk of erosive esophagitis with odds ratio (OR) of 1.9 (95% confidence interval (CI) 1.1-3.0, p=0.013) and 1.7 (95% CI 1.1-2.8, p=0.036), respectively. Combination of these two alleles increased the risk with OR of 3.2(95% CI 1.6-6.5, p=0.001). In conclusion, ND1+32656 GG and IL-8-251 T/T allele may be associated with less reactivity to H. pylori infection, and may increase the risk of erosive esophagitis even in H. pylori infected Japanese population.

CARD15/NOD2, CD14 and toll-like 4 receptor gene polymorphisms in Saudi patients with Crohn's Disease

Crohn’s disease (CD) is a multifactorial disease with a genetic component and an observed association with genes related to the innate immune response. Polymorphisms in the CARD15/NOD2 gene, in addition to functional variants of the toll-like receptor-4 (TLR4) and CD14 genes, have been associated with the development of Crohn’s disease. There is no information about the frequency of these polymorphisms in the Saudi population. We examined the frequency of the three major CARD15/NOD2 risk alleles (Leu1007fsinsC, Arg702Trp, and Gly908Arg) and the TLR4 (Thr399Il) polymorphism as well as a functional polymorphism in the promoter of the CD14–159C/T in 46 Saudi CD patients and 50 matched controls. Genotyping was performed by allele-specific PCR or by restriction fragment length polymorphism (PCR-RFLP) analysis. The mutant genotype frequencies of the Leu1007fsinsC, Arg702Trp and Gly908Arg in the patient group were 6.5, 21.7 and 6.5%, respectively, compared with frequencies of 0, 4 and 2%, respectively, in the control group. There were 15 patients who carried the mutant alleles for all three CARD15/NOD2 variants, Leu1007fsinsC, Arg702Trp and Gly908Arg, while none of the control candidates carried the three alleles. This genetic study provides evidence that the three major CARD15/NOD2 variant alleles and the CD14 –159C/T polymorphism are associated with Crohn’s disease (CD) susceptibility in the Saudi population; however, there is no evidence that the TLR4 (Thr399Il) or CARD15/NOD2 polymorphisms can be considered risk factors for Crohn’s disease.

Variants of NOD1 and NOD2 genes display opposite associations with familial risk of Crohn's disease and anti-saccharomyces cerevisiae antibody levels

BACKGROUND

NOD2 is involved in Crohn's disease (CD), but the role of NOD1 remains unclear. Anti-Saccharomyces cerevisiae antibodies (ASCA) are higher in CD patients and some of their relatives. Using family-based analyses we investigated the relationships between NOD2 mutations, NOD1 +32656 variant, and both the risk of CD and ASCA levels. We compared allelic frequencies between families with multiple CD cases (multiplex), those with one case of CD (simplex), and control families, searching for a gradient of at risk alleles according to the prevalence of the disease among families.

METHODS

In all, 93 CD patients, 160 healthy relatives from 22 multiplex families, 22 CD patients and 81 healthy relatives from 22 simplex families, and 169 subjects from 27 control families were included in the study. ASCA levels were determined by enzyme-linked immunosorbent assay. NOD1 +32656, NOD2 R702W, G908R, and 1007fs were genotyped by polymerase chain reaction / restriction fragment length polymorphism.

RESULTS

In family-based analyses NOD2 mutations and the NOD1 wildtype allele were associated with CD in multiplex families, with a synergetic effect when risk alleles of both genes were transmitted. Lower ASCA levels were strongly associated with the NOD1 variant allele. Simplex families had a lower frequency of the "at risk" +32656 allele than multiplex families.

CONCLUSIONS

The +32656 variant was associated with low ASCA level and low risk of CD in multiplex families. NOD2 and NOD1 variants displayed antagonist effects on the risk of CD and ASCA level. A gradient of NOD1, NOD2 at-risk alleles was associated with the variable prevalence of CD in families.

The prognostic power of the NOD2 genotype for complicated Crohn's disease: a meta-analysis

OBJECTIVES

Crohn's disease is often purely inflammatory at presentation, but most patients develop strictures and fistulae over time (complicated disease). Many studies have suggested that nucleotide-binding oligomerization domain 2 (NOD2) mutations are associated with a varying but increased risk of complicated disease. An accurate and sufficiently powerful predictor of complicated disease could justify the early use of biological therapy in high-risk individuals. We performed a systematic review and meta-analysis to obtain accurate estimates of the predictive power of the identified mutations (such as p.R702W, P.G908R, and p.Leu1007fsX1008) in NOD2 for the risk of complicated disease.

METHODS

An electronic search of MEDLINE, Embase, and Web of Science identified 917 relevant papers. Inclusion required specification of genetic mutations at the individual level and disease phenotypes by Vienna classification (inflammatory (B1), stricturing (B2), and fistulizing (B3)). A total of 49 studies met these criteria, which included 8,893 subjects, 2,897 of whom had NOD2 mutations. Studies were weighted by median disease duration. Studies not providing duration data were weighted at the level of the study with the shortest disease duration (3.9 years).

RESULTS

The relative risk (RR) of the presence of any NOD2 mutant allele for complicated disease (B2 or B3) was 1.17 (95% confidence interval (95% CI) 1.10-1.24; P<0.001). P.G908R was associated with an RR of complicated disease of 1.33 (95% CI 1.11-1.60; P=0.002). NOD2 did not predict perianal disease (P=0.4). The RR of surgery was 1.58 (95% CI 1.38-1.80; P<0.001). There was substantial heterogeneity across all studies (I(2)=66.7%). On the basis of logistic regression of these data, the sensitivity of any mutation in predicting complicated disease was 36% and specificity was 73%, with the area under the receiver operating characteristic curve 0.56.

CONCLUSIONS

The presence of a single NOD2 mutation predicted an 8% increase in the risk for complicated disease (B2 or B3), and a 41% increase with 2 mutations. Surgery risk is increased by 58% with any NOD2 mutation, whereas perianal disease was unchanged. The predictive power associated with a single NOD2 mutation is weak. The RR of any NOD2 mutations for complicated disease was only 17% across 36 studies. However, the presence of two NOD2 mutations had 98% specificity for complicated disease. These data provide insufficient evidence to support top-down therapy based solely on single NOD2 mutations, but suggest that targeted early-intensive therapy for high-risk patients with two NOD2 mutations might be beneficial, if prospective trials can demonstrate changes in the natural history in this subset of patients.

The role of bacteria and pattern-recognition receptors in Crohn's disease

Crohn's disease is widely regarded as a multifactorial disease, and evidence from human and animal studies suggests that bacteria have an instrumental role in its pathogenesis. Comparison of the intestinal microbiota of patients with Crohn's disease to that of healthy controls has revealed compositional changes. In most studies these changes are characterized by an increase in the abundance of Bacteroidetes and Proteobacteria and a decrease in that of Firmicutes. In addition, a number of specific mucosa-associated bacteria have been postulated to have a role in Crohn's disease, including Mycobacterium avium subspecies paratuberculosis, adherent and invasive Escherichia coli, Campylobacter and Helicobacter species. The association between mutations in pattern-recognition receptors (Toll-like receptors and Nod-like receptors) and autophagy proteins and Crohn's disease provides further evidence to suggest that defective sensing and killing of bacteria may drive the onset of disease. In this Review, we present recent advances in understanding the role of bacteria and the contribution of pattern-recognition receptors and autophagy in the pathogenesis of Crohn's disease.

Association of NOD1 (CARD4) insertion/deletion polymorphism with susceptibility to IBD: A meta-analysis

AIM: To find evidences about whether NOD1/CARD4 insertion/deletion polymorphism is associated with inflammatory bowel disease by meta-analysis.

METHODS: We surveyed the studies on the association of NOD1/CARD4 insertion/deletion polymorphism with inflammatory bowel disease in PubMed. Meta-analysis was performed for genotypes GG/T vs T/T, GG/GG vs T/T, GG/T + GG/GG vs T/T, GG/GG vs T/T + GG/T, and GG allele vs T allele in a fixed/random effect model.

RESULTS: We identified 8 studies (6439 cases and 4798 controls) in Caucasian populations using PubMed search. We found no association between NOD1/CARD4 insertion/deletion polymorphism and inflammatory bowel disease, Crohn’s disease, and ulcerative colitis. Stratification of cases by age showed that NOD1/CARD4 insertion/deletion polymorphism was associated with inflammatory bowel disease in younger age group at onset (< 40 years) (GG vs T: OR = 0.68, 95% CI: 0.50-0.93, P = 0.02; GG/T + GG/GG vs T/T: OR = 0.71, 95% CI: 0.59-0.85, P = 0.0003).

CONCLUSION: This meta-analysis demonstrates an association between NOD1/CARD4 insertion/deletion polymorphism and inflammatory bowel disease in the younger age group at onset (< 40 years) in Caucasian populations.

MDP-Induced selective tolerance to TLR4 ligands: impairment in NOD2 mutant Crohn's disease patients

BACKGROUND

Pathogen infection is a complex process in which several pathogen-recognition receptor (PRR) pathways are activated to induce proinflammatory mediators. The activation of multiple PRRs suggests an interaction between Toll-like receptors (TLRs) and nucleotide-binding oligomerization domain-like receptor (NOD) signaling pathways.

METHODS

To understand the modulation induced by NOD2 signals on successive responses to pathogen-associated molecular patterns (PAMPs), we examined how muramyl dipeptide (MDP) pretreatment reprograms the MDP+LPS (lipopolysaccharide) response of monocytes from human peripheral blood.

RESULTS

Preexposure to bacterial MDP components induced selective tolerance to a subsequent NOD2+TLR4 stimulation. MDP pretreatment inhibited the production of tumor necrosis factor alpha (TNFalpha) and interleuken 10 (IL10), whereas IL6 and IL8 remained unaffected. MDP-induced tolerance was independent of receptor downregulation but was associated with reduced levels of phosphorylated TAK1 and abrogated phosphorylation of the downstream MAPK.Since Nod2 mutations have been associated with susceptibility to develop Crohn's disease (CD), we compared the MDP-induced tolerance in healthy donors and CD patients with compound heterozygous Nod2 mutations (Mut-Nod2) expressing variant NOD2 proteins. MDP-induced tolerance in Mut-Nod2 patients reduced IL10 but not TNFalpha production. In contrast with healthy donors, a p38-independent TNFalpha production was observed during the kinetics of the MDP+LPS response in Mut-Nod2 patients.

CONCLUSIONS

Our findings suggest that the selective tolerance induced by MDP in healthy donors was related to the modulation of a convergent nub of NOD2 and TLR4 signaling pathways. This MDP-induced tolerance was impaired in Mut-Nod2 CD patients, resulting in a p38-independent TNFalpha production and an imbalance between pro- and antiinflammatory cytokines that could be partly responsible for the pathogenesis of CD.

Nucleotide-binding oligomerization domain containing 1 (NOD1) haplotypes and single nucleotide polymorphisms modify susceptibility to inflammatory bowel diseases in a New Zealand caucasian population: a case-control study

BACKGROUND

The nucleotide-binding oligomerization domain containing 1 (NOD1) gene encodes a pattern recognition receptor that senses pathogens, leading to downstream responses characteristic of innate immunity. We investigated the role of NOD1 single nucleotide polymorphisms (SNPs) on IBD risk in a New Zealand Caucasian population, and studied Nod1 expression in response to bacterial invasion in the Caco2 cell line.

FINDINGS

DNA samples from 388 Crohn's disease (CD), 405 ulcerative colitis (UC), 27 indeterminate colitis patients and 201 randomly selected controls, from Canterbury, New Zealand were screened for 3 common SNPs in NOD1, using the MassARRAY iPLEX Gold assay. Transcriptional activation of the protein produced by NOD1 (Nod1) was studied after infection of Caco2 cells with Escherichia coli LF82. Carrying the rs2075818 G allele decreased the risk of CD (OR = 0.66, 95% CI = 0.50-0.88, p < 0.002) but not UC. There was an increased frequency of the three SNP (rs2075818, rs2075822, rs2907748) haplotype, CTG (p = 0.004) and a decreased frequency of the GTG haplotype (p = 0.02).in CD. The rs2075822 CT or TT genotypes were at an increased frequency (genotype p value = 0.02), while the rs2907748 AA or AG genotypes showed decreased frequencies in UC (p = 0.04), but not in CD. Functional assays showed that Nod1 is produced 6 hours after bacterial invasion of the Caco2 cell line.

CONCLUSION

The NOD1 gene is important in signalling invasion of colonic cells by pathogenic bacteria, indicative of its' key role in innate immunity. Carrying specific SNPs in this gene significantly modifies the risk of CD and/or UC in a New Zealand Caucasian population.