Polymorphisms in interleukin-10 gene according to mutations of NOD2/CARD15 gene and relation to phenotype in Spanish patients with Crohn’s disease

Polymorphisms of the cytokine genes TGFB1 and IL10 in a mixed-race population with Crohn's disease

Background

Most Crohn’s disease (CD) genes discovered in recent years are associated with biological systems critical to the development of this disease. TGFB1 and IL10 are cytokines with important roles in CD. The aim of this study was to evaluate the association between CD, its clinical features and TGFB1 and IL10 gene polymorphisms.

Methods

This case–control study enrolled 91 patients and 91 controls from the state of Bahia, Brazil. Five single nucleotide polymorphisms (SNPs) were studied in the TGFB1 gene (codon 10 T > C - rs1800470; codon 25 G > C - rs1800471) and IL10 gene (−1082 A > G - rs1800896; -819 T > C - rs1800871; -592 A > C - rs1800872). An analysis of the genetic polymorphisms was performed using a commercial kit. A comparison of allele frequencies and genotypes was estimated by calculating the odds ratio (OR) with a confidence interval adjusted via the Bonferroni test for a local alpha of 1%. A stratified analysis was applied for gender, race and smoking history. Patients with CD were characterized according to the Montreal classification.

Results

The C allele and CC genotype of the TGFB1 gene rs1800470 were both significantly associated with CD. The stratified analysis showed no confounding factors for the co-variables of gender, race and smoking history. The IL10 gene rs1800896 G allele was significantly associated with age at diagnosis of CD, while the T allele of the IL10 gene rs1800871 was significantly associated with perianal disease. The SNPs rs1800871 and rs1800872 were in 100% linkage disequilibrium.

Conclusions

TGFB1 gene polymorphisms may be associated with susceptibility to the development of CD, and IL10 gene polymorphisms appear to influence the CD phenotype in this admixed population.

The impact of smoking in Crohn's disease: no smoke without fire

Smoking habit is the most widely accepted environmental factor affecting the incidence and disease progression in the inflammatory bowel diseases. The contrasting effects in Crohn's disease (CD) and ulcerative colitis are unexplained. The purpose of this review is to summarise the existing data on the effects of smoking in CD on disease history, recurrence after surgery, effects on drug responses and to review available evidence that carriage of some of the known susceptibility genes may be disproportionate in smokers with CD. The review also highlights potential mechanisms involved and factors that might affect patients' smoking habits. The clinical and scientific implications of the data are discussed.

Interleukin 10 (IL-10) gene variants and susceptibility for paediatric onset Crohn's disease

BACKGROUND

A recent genome-wide association study in adult patients with ulcerative colitis (UC) has implicated the interleukin 10 (IL-10) gene as an important candidate gene. Moreover, a UC-associated single nucleotide polymorphism (SNP) rs3024405 was also significantly associated with adult Crohn's disease (CD).

AIMS

To examine whether IL-10-CD associations extended to paediatric-onset CD.

METHODS

We implemented the case-control design at three paediatric gastroenterology clinics in Canada. CD patients (<or=20 years) were recruited along with healthy controls. DNA samples were genotyped for tag-single nucleotide polymorphisms (tag-SNPs) in the IL-10 gene. Allelic, genotype and haplotype associations with CD were studied.

RESULTS

A total of 270 patients and 336 controls were studied. The mean age (+/-s.d.) at diagnosis was 12.1 (+/-3.5). There were a slightly higher proportion of male patients (56.3%). Of the five IL-10 tag-SNPs, rs2222202 (C/T) (P = 0.03) and rs1800871 (C/T) (P = 0.05) showed significant allelic associations with CD. Specific IL-10 SNPs were associated with CD disease location and/or disease behaviour.

CONCLUSIONS

Our gene-wide analysis replicates recent findings of associations between IL-10 and adult CD, and suggests that these associations extend to paediatric-onset CD as well.