Polymorphisms in the Toll-Like Receptor and the IL-23/IL-17 Pathways Were Associated with Susceptibility to Inflammatory Bowel Disease in a Danish Cohort

BACKGROUND

The inflammatory bowel diseases (IBD), Crohn's disease (CD) and ulcerative colitis (UC), result from the combined effects of susceptibility genes and environmental factors. Previous studies have shown that polymorphisms in the Toll-like receptor (TLR), the apoptosis, the IL-23/IL-17 and the interferon gamma (IFNG) pathways are associated with risk of both CD and UC.

METHODS

Using a candidate gene approach, 21 functional single nucleotide polymorphisms (SNPs) in 15 genes were assessed in a clinical homogeneous group of severely diseased ethnic Danish patients consisting of 624 patients with CD, 411 patients with UC and 795 controls. The results were analysed using logistic regression.

RESULTS

The polymorphisms TLR5 (rs5744174) and IL12B (rs6887695) were associated with risk of CD, and TLR1 (rs4833095) and IL18 (rs187238) were associated with risk of both CD and UC (p<0.05). After Bonferroni correction for multiple testing, the homozygous variant genotype of TLR1 743 T>C (rs4833095) was associated with increased risk CD (OR: 3.15, 95% CI: 1.59-6.26, p = 0.02) and CD and UC combined (OR: 2.96, 95% CI: 1.64-5.32, p = 0.005).

CONCLUSION

Our results suggest that genetically determined high activity of TLR1 and TLR5 was associated with increased risk of both CD and UC and CD, respectively. This supports that the host microbial composition or environmental factors in the gut are involved in risk of IBD. Furthermore, genetically determined high activity of the IL-23/IL-17 pathway was associated with increased risk of CD and UC. Overall, our results support that genetically determined high inflammatory response was associated with increased risk of both CD and UC.

Effectiveness of anti-tumour necrosis factor-α therapy in Danish patients with inflammatory bowel diseases

INTRODUCTION

The objective of this study was to evaluate the outcome of anti-tumour necrosis factor-α (anti-TNF) treatment in a large cohort of patients with inflammatory bowel diseases (IBD), including Crohn's disease (CD) and ulcerative colitis (UC) in clinical practice and to establish a cohort for future studies of genetic markers associated with treatment response.

METHODS

A national, clinically based cohort of previously naïve anti-TNF treated patients from 18 medical departments was established. The patients were screened for tuberculosis prior to treatment initiation. By combining the unique personal identification number of Danish citizens (the CPR number) from blood samples with data from the National Patient Registry, patients with International Classification of Diseases, Version 10 (ICD-10) codes K50-K63 were identified. Treatment efficacy reflected the maximum response within 22 weeks.

RESULTS

Among 492 patients with CD and 267 patients with UC, 74%/13%/14% and 65%/12%/24% were responders, partial responders and non-responders to anti-TNF therapy, respectively. More patients with UC than with CD were non-responders (odds ratio (OR) = 1.96, 95% confidence interval (CI): 1.34-2.87, p = 0.001). Young age was associated with a beneficial response (p = 0.03), whereas smoking ≥ 10 cigarettes/day was associated with non-response among patients with CD (OR = 2.33, 95% CI: 1.13-4.81, p = 0.03).

CONCLUSION

In this clinically based cohort of Danish patients with IBD treated with anti-TNF, high response rates were found. Heavy smoking was associated with non-response, whereas young age at treatment initiation was associated with a beneficial response among patients with CD. Thus, the results obtained in this cohort recruited from clinical practice were similar to those previously obtained in clinical trials.

FUNDING

The work was funded by Health Research Fund of Central Denmark Region, Colitis-Crohn Foreningen and the University of Aarhus (PhD grant).

TRIAL REGISTRATION

Clinicaltrials NCT02322008.

Polymorphisms in the inflammatory pathway genes TLR2, TLR4, TLR9, LY96, NFKBIA, NFKB1, TNFA, TNFRSF1A, IL6R, IL10, IL23R, PTPN22, and PPARG are associated with susceptibility of inflammatory bowel disease in a Danish cohort

BACKGROUND

The inflammatory bowel diseases (IBD), Crohn's disease (CD) and ulcerative colitis (UC), result from the combined effects of susceptibility genes and environmental factors. Polymorphisms in genes regulating inflammation may explain part of the genetic heritage.

METHODS

Using a candidate gene approach, 39 mainly functional single nucleotide polymorphisms (SNPs) in 26 genes regulating inflammation were assessed in a clinical homogeneous group of severely diseased patients consisting of 624 patients with CD, 411 patients with UC and 795 controls. The results were analysed using logistic regression.

RESULTS

Sixteen polymorphisms in 13 genes involved in regulation of inflammation were associated with risk of CD and/or UC (p ≤ 0.05). The polymorphisms TLR2 (rs1816702), NFKB1 (rs28362491), TNFRSF1A (rs4149570), IL6R (rs4537545), IL23R (rs11209026) and PTPN22 (rs2476601) were associated with risk of CD and the polymorphisms TLR2 (rs1816702), TLR4 (rs1554973 and rs12377632), TLR9 (rs352139), LY96 (rs11465996), NFKBIA (rs696), TNFA (rs1800629), TNFRSF1A (rs4149570), IL10 (rs3024505), IL23R (rs11209026), PTPN22 (rs2476601) and PPARG (rs1801282) were associated with risk of UC. When including all patients (IBD) the polymorphisms TLR2 (rs4696480 and rs1816702), TLR4 (rs1554973 and rs12377632), TLR9 (rs187084), TNFRSF1A (rs4149570), IL6R (rs4537545), IL10 (rs3024505), IL23R (rs11209026) and PTPN22 (rs2476601) were associated with risk. After Bonferroni correction for multiple testing, both the homozygous and the heterozygous variant genotypes of IL23R G>A(rs11209026) (OR(CD,adj): 0.38, 95% CI: 0.21-0.67, p = 0.03; OR(IBD,adj) 0.43, 95% CI: 0.28-0.67, p = 0.007) and PTPN22 1858 G>A(rs2476601) (OR(CD,unadj) 0.54, 95% CI: 0.41-0.72, p = 7*10-4; OR(IBD,unadj): 0.61, 95% CI: 0.48-0.77, p = 0.001) were associated with reduced risk of CD.

CONCLUSION

The biological effects of the studied polymorphisms suggest that genetically determined high inflammatory response was associated with increased risk of CD. The many SNPs found in TLRs suggest that the host microbial composition or environmental factors in the gut are involved in risk of IBD in genetically susceptible individuals.

Associations between functional polymorphisms in the NFκB signaling pathway and response to anti-TNF treatment in Danish patients with inflammatory bowel disease

Antitumor necrosis factor-α (TNF-α) is used for treatment of severe cases of inflammatory bowel diseases (IBD), including Crohn's disease (CD) and ulcerative colitis (UC). However, one-third of the patients do not respond to the treatment. Genetic markers may predict individual response to anti-TNF therapy. Using a candidate gene approach, 39 mainly functional single nucleotide polymorphisms (SNPs) in 26 genes regulating inflammation were assessed in 738 prior anti-TNF-naive Danish patients with IBD. The results were analyzed using logistic regression (crude and adjusted for age, gender and smoking status). Nineteen functional polymorphisms that alter the NFκB-mediated inflammatory response (TLR2 (rs3804099, rs11938228, rs1816702, rs4696480), TLR4 (rs5030728, rs1554973), TLR9 (rs187084, rs352139), LY96 (MD-2) (rs11465996), CD14 (rs2569190), MAP3K14 (NIK) (rs7222094)), TNF-α signaling (TNFA (TNF-α) (rs361525), TNFRSF1A (TNFR1) (rs4149570), TNFAIP3(A20) (rs6927172)) and other cytokines regulated by NFκB (IL1B (rs4848306), IL1RN (rs4251961), IL6 (rs10499563), IL17A (rs2275913), IFNG (rs2430561)) were associated with response to anti-TNF therapy among patients with CD, UC or both CD and UC (P ⩽ 0.05). In conclusion, the results suggest that polymorphisms in genes involved in activating NFκB through the Toll-like receptor (TLR) pathways, genes regulating TNF-α signaling and cytokines regulated by NFκB are important predictors for the response to anti-TNF therapy among patients with IBD. Genetically strong TNF-mediated inflammatory response was associated with beneficial response. In addition, the cytokines IL-1β, IL-6 and IFN-γ may be potential targets for treating patients with IBD who do not respond to anti-TNF therapy. These findings should be examined in independent cohorts before these results are applied in a clinical setting.