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.

BackgroundThe 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.MethodsUsing 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.ResultsSixteen 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) (ORCD,adj: 0.38, 95% CI: 0.21–0.67, p = 0.03; ORIBD,adj 0.43, 95% CI: 0.28–0.67, p = 0.007) and PTPN22 1858 G>A(rs2476601) (ORCD,unadj 0.54, 95% CI: 0.41–0.72, p = 7*10−4; ORIBD,unadj: 0.61, 95% CI: 0.48–0.77, p = 0.001) were associated with reduced risk of CD.ConclusionThe 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.

SummaryBackgroundPersonalised medicine, including biomarkers for treatment selection, may provide new algorithms for more effective treatment of patients. Genetic variation may impact drug response and genetic markers could help selecting the best treatment strategy for the individual patient.AimTo identify polymorphisms and candidate genes from the literature that are associated with anti‐tumour necrosis factor (TNF) treatment response in patients with inflammatory bowel diseases (IBD), Crohn's disease (CD) and ulcerative colitis.MethodsWe performed a PubMed literature search and retrieved studies reporting original data on association between polymorphisms and anti‐TNF treatment response and conducted a meta‐analysis.ResultsA functional polymorphism in FCGR3A was significantly associated with anti‐TNF treatment response among CD patients using biological response criterion (decrease in C‐reactive protein, levels). Meta‐analyses showed that polymorphisms in TLR2 (rs3804099, OR (95% CI) = 2.17 (1.35–3.47)], rs11938228 [OR = 0.64 (0.43–0.96)], TLR4 (rs5030728) [OR = 3.18 (1.63–6.21)], TLR9 (rs352139) [OR = 0.43 (0.21–0.88)], TNFRSF1A (rs4149570) [OR = 2.06 (1.02–4.17)], IFNG (rs2430561) [OR = 1.66 (1.05–2.63)], IL6 (rs10499563) [OR = 1.65 (1.04–2.63)] and IL1B (rs4848306) [OR = 1.88 (1.05–3.35)] were significantly associated with response among IBD patients using clinical response criteria. A positive predictive value of 0.96 was achieved by combining five genetic markers in an explorative analysis.ConclusionsThere are no genetic markers currently available which are adequately predictive of anti‐TNF response for use in the clinic. Genetic markers bear the advantage that they do not change over time. Therefore, hypothesis‐free approaches, testing a large number of polymorphisms in large, well‐characterised cohorts, are required in order to identify genetic profiles with larger effect sizes, which could be employed as biomarkers for treatment selection in clinical settings.