Nuclear pregnane X receptor single nucleotide polymorphism (-25385C/T) is not associated with inflammatory bowel disease in pediatric patients

Relationship between NR1I2 polymorphisms and inflammatory bowel disease risk: A systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

Inconsistent results regarding an association between polymorphisms within the Homo sapiens nuclear receptor subfamily 1 group I member 2 (NR1I2) gene and susceptibility to inflammatory bowel disease (IBD) have been reported. A systematic review and meta-analysis was thus undertaken to determine whether NR1I2 gene polymorphisms are associated with an increased risk of IBD.

METHODS

Article retrieval was performed using on-line databases, such as PubMed, Embase, CENTRAL, and WOS. After extracting eligible data, Mantel-Haenszel statistics were applied to calculate the odds radio (OR), 95% confidence interval (95% CI) and P value under a random or fixed-effects model.

RESULTS

A total of seven articles with 4410 IBD subjects and 4028 controls were included. Compared with the control group, no significant increase in IBD susceptibility was observed for the -25385C/T (OR=0.92, 95% CI=0.78∼1.07, P=0.259), -24381A/C (OR=0.96, 95% CI=0.87∼1.06, P=0.378), +8055C/T (OR=1.06, 95% CI=0.97∼1.15, P=0.186), or +7635A/G (OR=0.96, 95% CI=0.87∼1.05, P=0.348) polymorphisms within the NR1I2 gene under the allele model.

CONCLUSIONS

Our meta-analysis failed to demonstrate an association between -25385C/T, -24381A/C, +8055C/T, or +7635A/G polymorphisms within the NR1I2 gene and overall IBD risk. A larger sample size is needed to validate our conclusion.

PXR variants and artemisinin use in Vietnamese subjects: frequency distribution and impact on the interindividual variability of CYP3A induction by artemisinin

Artemisinins induce drug metabolism through the activation of the pregnane X receptor (PXR) in vitro. Here, we report the resequencing and genotyping of PXR variants in 75 Vietnamese individuals previously characterized for CYP3A enzyme activity after artemisinin exposure. We identified a total of 31 PXR variants, including 5 novel single nucleotide polymorphisms (SNPs), and we identified significantly different allele frequencies relative to other ethnic groups. A trend of significance was observed between the level of CYP3A4 induction by artemisinin and two PXR variants, the 8118C→T (Y328Y) and 10719A→G variants.

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.