Nasopharyngeal bacterial colonization and gene polymorphisms of mannose-binding lectin and toll-like receptors 2 and 4 in infants.
BACKGROUND
Human nasopharynx is often colonized by potentially pathogenic bacteria. Gene polymorphisms in mannose-binding lectin (MBL), toll-like receptor (TLR) 2 and TLR4 have been reported. The present study aimed to investigate possible association between nasopharyngeal bacterial colonization and gene polymorphisms of MBL, TLR2 and TLR4 in healthy infants.


RESULTS
From August 2008 to June 2010, 489 nasopharyngeal swabs and 412 blood samples were taken from 3-month-old healthy Finnish infants. Semi-quantitative culture was performed and pyrosequencing was used for detection of polymorphisms in MBL structural gene at codons 52, 54, and 57, TLR2 Arg753Gln and TLR4 Asp299Gly. Fifty-nine percent of subjects were culture positive for at least one of the four species: 11% for Streptococcus pneumoniae, 23% for Moraxella catarrhalis, 1% for Haemophilus influenzae and 25% for Staphylococcus aureus. Thirty-two percent of subjects had variant types in MBL, 5% had polymorphism of TLR2, and 18% had polymorphism of TLR4. Colonization rates of S. pneumoniae and S. aureus were significantly higher in infants with variant types of MBL than those with wild type (p = .011 and p = .024). Colonization rates of S. aureus and M. catarrhalis were significantly higher in infants with polymorphisms of TLR2 and of TLR4 than those without (p = .027 and p = .002).


CONCLUSIONS
Our study suggests that there is an association between nasopharyngeal bacterial colonization and genetic variation of MBL, TLR2 and TLR4 in young infants. This finding supports a role for these genetic variations in susceptibility of children to respiratory infections.
Department of Infectious Disease Surveillance and Control, National Institute for Health and Welfare, Turku, Finland.
Juho
J
Vuononvirta
Laura
L
Toivonen
Kirsi
K
Gröndahl-Yli-Hannuksela
Alex-Mikael
AM
Barkoff
Laura
L
Lindholm
Jussi
J
Mertsola
Ville
V
Peltola
Qiushui
Q
He
D001419:Bacteria / Q000254:growth & development*; D015169:Colony Count, Microbial; D005387:Finland; D005838:Genotype; D006262:Health; D006801:Humans; D007223:Infant; D037601:Mannose-Binding Lectin / Q000235:genetics; D009305:Nasopharynx / Q000382:microbiology*; D011110:Polymorphism, Genetic; D013045:Species Specificity; D051195:Toll-Like Receptor 2 / Q000235:genetics*; D051197:Toll-Like Receptor 4 / Q000235:genetics*
C445619:MBL2 protein, human; D037601:Mannose-Binding Lectin; C495342:TLR2 protein, human; C495345:TLR4 protein, human; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4