Objective: To explore the distribution of Toll-like receptors gene polymorphisms in inflammatory bowel disease (IBD) in Chinese Han patients and Caucasians.
Methods: The toll-like receptor 2 (TLR2) genes Arg677Trp and Arg753Glu, TLR4 genes Asp299Gly and Thr399Ile, and TLR9 gene 1237T/C polymorphisms were genotypes in 113 patients with IBD and 120 age and gender-matched healthy controls by the analyses of polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP). A meta-analysis was performed to test whether TLR4 Asp299Gly and Thr399Ile polymorphisms were associated with ulcerative colitis (UC) or Crohn's disease (CD) susceptibility and whether 299Gly carriage was associated with phenotypes of CD patients in the Caucasian population.
Results: We found two carriers of TLR9 1237C in UC patients, one carrier in CD patients and one in healthy controls respectively (CD: P = 0.361; UC: P = 0.569). There was no statistically significant difference in both allelic and genotypic frequencies. The mutant genotypes of TLR2 gene Arg677Trp and Arg753Glu, TLR4 gene Asp299Gly and Thr399Ile were not found in either the IBD patients or the healthy controls. The TLR4 299G allele showed a significant association with CD and UC in Caucasian population (OR = 1.29, 95%CI: 1.08 - 1.54, P = 0.004 and OR = 1.28, 95%CI: 1.08 - 1.51, P = 0.004 respectively). Similar association was detected between T399I polymorphism and susceptibility to IBD (OR = 1.37, 95%CI: 1.12 - 1.68, P = 0.002 and OR = 1.46, 95%CI: 1.13 - 1.88, P = 0.003 respectively). However, no significant association was identified between CD phenotypes and 299Gly carriage.
Conclusion: TLR2 genes Arg677Trp and Arg753Glu, TLR4 genes Asp299Gly and Thr399Ile and TLR9 gene 1237T/C polymorphisms are not associated with IBD in Chinese Han patients. In Caucasians, both TLR4 299G and 399I confer a significant risk for developing CD and UC. The contribution of genetic determinants may differ significantly between ethnicities.