title: TLR4 Asp299Gly and Thr399Ile polymorphisms: no impact on human immune responsiveness to LPS or respiratory syncytial virus.
abstract: BACKGROUND
  A broad variety of natural environmental stimuli, genotypic influences and timing all contribute to expression of protective versus maladaptive immune responses and the resulting clinical outcomes in humans. The role of commonly co-segregating Toll-like receptor 4 (TLR4) non-synonymous single nucleotide polymorphisms Asp299Gly and Thr399Ile in this process remains highly controversial. Moreover, what differential impact these polymorphisms might have in at risk populations with respiratory dysfunction, such as current asthma or a history of infantile bronchiolitis, has never been examined. Here we determine the importance of these polymorphisms in modulating LPS and respiratory syncytial virus (RSV)--driven cytokine responses. We focus on both healthy children and those with clinically relevant respiratory dysfunction.
  
  
  METHODS
  To elucidate the impact of TLR4 Asp299Gly and Thr399Ile on cytokine production, we assessed multiple immune parameters in over 200 pediatric subjects aged 7-9. Genotyping was followed by quantification of pro- and anti-inflammatory cytokine responses by fresh peripheral blood mononuclear cells upon acute exposure to LPS or RSV.
  
  
  RESULTS
  In contrast to early reports, neither SNP influenced immune responses evoked by LPS exposure or RSV infection, as measured by the intermediate phenotype of pro- and anti-inflammatory cytokine responses to these ubiquitous agents. There is no evidence of altered sensitivity in populations with "at risk" clinical phenotypes.
  
  
  CONCLUSIONS
  Genomic medicine seeks to inform clinical practice. Determination of the TLR4 Asp299Gly/Thr399Ile haplotype is of no clinical benefit in predicting the nature or intensity of cytokine production in children whether currently healthy or among specific at-risk groups characterized by prior infantile broncholitis or current asthma.
authors: CIHR National Training Program in Allergy and Asthma Research, Department of Immunology, University of Manitoba, Winnipeg, Canada.
authors: Renée N
authors: RN
authors: Douville
authors: Yuriy
authors: Y
authors: Lissitsyn
authors: Aaron F
authors: AF
authors: Hirschfeld
authors: Allan B
authors: AB
authors: Becker
authors: Anita L
authors: AL
authors: Kozyrskyj
authors: Joel
authors: J
authors: Liem
authors: Nathalie
authors: N
authors: Bastien
authors: Yan
authors: Y
authors: Li
authors: Rachel E
authors: RE
authors: Victor
authors: Mehtab
authors: M
authors: Sekhon
authors: Stuart E
authors: SE
authors: Turvey
authors: Kent T
authors: KT
authors: HayGlass
mesh_terms: D001249:Asthma / Q000235:genetics / Q000276:immunology / Q000821:virology; D001988:Bronchiolitis / Q000235:genetics / Q000276:immunology / Q000821:virology; D002648:Child; D016207:Cytokines / Q000096:biosynthesis; D006239:Haplotypes / Q000276:immunology; D006801:Humans; D007109:Immunity / Q000235:genetics*; D008070:Lipopolysaccharides / Q000276:immunology*; D020641:Polymorphism, Single Nucleotide / Q000276:immunology*; D012136:Respiratory Syncytial Viruses / Q000276:immunology*; D051197:Toll-Like Receptor 4 / Q000235:genetics*
chemical_list: D016207:Cytokines; D008070:Lipopolysaccharides; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4