TLR5 risk-associated haplotype for canine inflammatory bowel disease confers hyper-responsiveness to flagellin

Aarti Kathrani, Angela Holder, Brian Catchpole, Lorena Alvarez, Kenneth Simpson, Dirk Werling, Karin Allenspach

Research output: Contribution to journalArticle (Academic Journal)peer-review

34 Citations (Scopus)

Abstract

Single nucleotide polymorphisms (SNP) in the TLR5 gene have been associated with human inflammatory bowel disease (IBD) and animal models of this disease. We recently demonstrated a significant association between three non-synonymous SNPs in the canine TLR5 gene and IBD in German shepherd dogs (GSDs). However, so far, no direct link between these SNPs and a disturbance in TLR5 function was shown. In the present study, we determined the functional significance of the canine TLR5 SNPs by transfecting the identified risk-protective and risk-associated haplotype into human embryonic kidney cells (HEK) and assessed nuclear factor-kappa B (NF-κB) activation and CXCL8 production after stimulation. In addition, a whole blood assay for TLR5 activation was developed using blood derived from carrier dogs of either haplotype. There was a significant increase in NF-kB activity when cells transfected with the risk-associated TLR5 haplotype were stimulated with flagellin compared to the cells expressing the risk-protective TLR5 haplotype. This difference in NFkB activation correlated with CXCL8 expression in the supernatant measured by ELISA. Furthermore, whole blood taken from carrier dogs of the risk-associated TLR5 haplotype produced significantly more TNF after stimulation with flagellin compared to that taken from carriers of the risk-protective haplotype. Thus, we show for the first time a direct functional impact of the canine IBD risk-associated TLR5 haplotype, which results in hyper-responsiveness to flagellin compared to the IBD risk-protective TLR5 haplotype. Our data potentially suggest that similarly to human IBD and experimental models, TLR5 may also play a role in canine IBD. Blocking the hyper-responsive receptor found in susceptible dogs with IBD may alleviate the inappropriate inflammation seen in this disease.

Original languageEnglish
Pages (from-to)e30117
JournalPLoS ONE
Volume7
Issue number1
DOIs
Publication statusPublished - 2012

Keywords

  • Animals
  • Blood
  • Dogs
  • Flagellin
  • Genetic Predisposition to Disease
  • HEK293 Cells
  • Haplotypes
  • Humans
  • Inflammatory Bowel Diseases
  • Interleukin-8
  • Luminescent Proteins
  • Microscopy, Confocal
  • NF-kappa B
  • Polymorphism, Single Nucleotide
  • Risk Factors
  • Toll-Like Receptor 5
  • Tumor Necrosis Factor-alpha

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