Toll-like receptor-1, -2, and -6 polymorphisms influence disease extension in inflammatory bowel diseases.
BACKGROUND
Evidence that a deficient innate immune response toward the bacterial flora of the gut plays a role in the pathogenesis of inflammatory bowel disease (IBD) is growing. This is underscored by the finding of the association between CARD15 variants and Crohn's disease (CD) and D299G in Toll-like receptor (TLR) 4 and IBD. Our aims were to study nonsynonymous polymorphisms in other TLR genes in IBD.


METHODS
Thirty-five single nucleotide polymorphisms (SNP) in TLR1-10 were identified from public databases. 284 IBD parent-child trios and a second independent cohort of 285 IBD patients and 191 healthy controls were genotyped with polymerase chain reaction-restriction fragment length polymorphisms. Patients were pooled for genotype-phenotype analyses.


RESULTS
Although none of the SNPs was involved in disease susceptibility, a number of variants influenced the disease phenotype. A positive association between TLR1 R80T and pancolitis in UC (P = .045, OR [95% CI] 2.844 [1.026-7.844]) was found. The TLR2 R753G SNP was also associated with pancolitis (P = .027, OR [95% CI] 4.741 [1.197-18.773]). The relative risks for heterozygous patients to develop pancolitis were 5.8 and 3.3 for R80T and R753G, respectively. There was a negative association between TLR6 S249P and ulcerative colitis with proctitis only (P = .026, OR [95% CI] 0.223 [0.096-0.705]). In CD, we found a negative association between ileal disease involvement and TLR1 S602I (P = .03, OR [95% CI] 0.522 [0.286-0.950]).


CONCLUSIONS
TLR2 and its cofactors TLR1 and TLR6 are involved in the initial immune response to bacteria by recognizing peptidoglycan. An association between nonsynonymous variants in the TLR1, -2, and -6 genes and extensive colonic disease in UC and CD was found. Our findings further highlight the role of an abnormal innate immune response in the pathogenesis of IBD.
Pierik
Marie
M
Department of Gastroenterology, University Hospital Gasthuisberg, Leuven, Belgium. Marieke.Pierik@uz.kuleuven.ac.be
Joossens
Sofie
S
Van Steen
Kristel
K
Van Schuerbeek
Nele
N
Vlietinck
Robert
R
Rutgeerts
Paul
P
Vermeire
Severine
S
D000328:Adult; D019268:Antibodies, Antineutrophil Cytoplasmic / Q000097:blood; D015415:Biomarkers / Q000097:blood; D003093:Colitis, Ulcerative / Q000235:genetics* / Q000276:immunology; D003424:Crohn Disease / Q000235:genetics* / Q000276:immunology; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics; D008297:Male; D015999:Multivariate Analysis; D053473:Nod2 Signaling Adaptor Protein; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide; D012441:Saccharomyces cerevisiae / Q000276:immunology; D051193:Toll-Like Receptors / Q000235:genetics* / Q000276:immunology
D019268:Antibodies, Antineutrophil Cytoplasmic; D015415:Biomarkers; D047908:Intracellular Signaling Peptides and Proteins; C429018:NOD2 protein, human; D053473:Nod2 Signaling Adaptor Protein; D051193:Toll-Like Receptors