title: Association between TLR2 and TLR4 Gene Polymorphisms and the Susceptibility to Inflammatory Bowel Disease: A Meta-Analysis.
abstract: BACKGROUND
  The associations between toll-like receptor 2 (TLR2) and toll-like receptor 4(TLR4) polymorphisms and inflammatory bowel disease (IBD) susceptibility remain controversial. A meta-analysis was performed to assess these associations.
  
  
  METHODS
  A systematic search was performed to identify all relevant studies relating TLR2 and TLR4 polymorphisms and IBD susceptibility. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. Subgroup analyses were performed by ethnicity and publication quality.
  
  
  RESULTS
  Thirty-eight eligible studies, assessing 10970 cases and 7061 controls were included. No TLR2 Arg677Trp polymorphism was found. No significant association was observed between TLR2 Arg753Gln polymorphism and Crohn's disease (CD) or ulcerative colitis (UC) in all genetic models. Interestingly, TLR4 Asp299Gly polymorphism was significantly associated with increased risk of CD and UC in all genetic models, except for the additive one in CD. In addition, a statistically significant association between TLR4 Asp299Gly polymorphism and IBD was observed among high quality studies evaluating Caucasians, but not Asians. Associations between TLR4 Thr399Ile polymorphisms and CD risk were found only in the allele and dominant models. The TLR4 Thr399Ile polymorphism was associated with UC risk in pooled results as well as subgroup analysis of high quality publications assessing Caucasians, in allele and dominant models.
  
  
  CONCLUSIONS
  The meta-analysis provides evidence that TLR2 Arg753Gln is not associated with CD and UC susceptibility in Asians; TLR4 Asp299Gly is associated with CD and UC susceptibility in Caucasians, but not Asians. TLR4 Thr399Ile may be associated with IBD susceptibility in Caucasians only. Additional well-powered studies of Asp299Gly and other TLR4 variants are warranted.
authors.affiliation: First clinical college, Southern Medical University, Guangzhou, Guangdong Province, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Cheng
authors.affiliation: Liver Tumor Center, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong Province, China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: First clinical college, Southern Medical University, Guangzhou, Guangdong Province, China.
authors.forename: Xiuping
authors.initials: X
authors.lastname: Huang
authors.affiliation: First clinical college, Southern Medical University, Guangzhou, Guangdong Province, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: First clinical college, Southern Medical University, Guangzhou, Guangdong Province, China.
authors.forename: Zelong
authors.initials: Z
authors.lastname: Han
authors.affiliation: Department of Digestion, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong Province, China.
authors.forename: Side
authors.initials: S
authors.lastname: Liu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D056726:Genetic Association Studies; D020022:Genetic Predisposition to Disease; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011110:Polymorphism, Genetic; D051195:Toll-Like Receptor 2 / Q000235:genetics*; D051197:Toll-Like Receptor 4 / Q000235:genetics*
chemical_list: C495342:TLR2 protein, human; C495345:TLR4 protein, human; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4