Multiplex analysis of toll-like receptor-stimulated neonatal cytokine response.
BACKGROUND
The human neonate's increased susceptibility to bacterial infections is not completely understood. Toll-like receptors (TLRs) have been recognized as pattern-recognition receptors critical to the innate immune response. TLR function in neonates, however, remains incompletely defined.


OBJECTIVE
To examine regulatory and proinflammatory cytokine responses to TLR-1-6 stimulation of cord blood compared to adult blood.


METHODS
We stimulated cord blood with ligands for each of TLRs 1-6 and compared these responses to adult controls. The following TLR ligands were utilized: Pam3CSK4 (TLR-1 and 2), zymosan (TLR-2 and 6), poly I:C (TLR-3), LPS (TLR-4), and flagellin (TLR-5). Cytokine production was measured with an assay developed in-house utilizing multi-analyte technology.


RESULTS
TLR-1-6 stimulation produced higher concentrations of proinflammatory cytokines (IL-1beta, IL-6, and IL-8) in cord blood compared to adult blood, with the exception of TLR-4-stimulated TNF-alpha production, which was significantly lower in cord blood (319 pg/ml) compared to adult blood (645 pg/ml; p = 0.027). In contrast, TLR-1-6 stimulation resulted in decreased concentrations of Th1 and Th2 cytokines in cord blood compared to adult blood, with significantly diminished production of IL-12 (TLRs 1/2, 2/6, 3 and 4), IL-13 (TLR-1-6), and IL-10 (TLR-4).


CONCLUSIONS
Cord blood production of regulatory Th1 and Th2 cytokines following TLR stimulation is decreased compared to that of adult blood. In contrast, TLR-stimulated proinflammatory cytokine production was markedly higher in neonates than in adults, with the exception of TLR-4-induced TNF-alpha production. The human neonate's increased susceptibility to bacterial infections may be related to abnormal TLR responsiveness, with enhanced proinflammatory and decreased regulatory cytokine production.
Caron
Justin E
JE
Department of Pathology, University of Utah School of Medicine, Salt Lake City, Utah 84132, USA.
La Pine
Timothy R
TR
Augustine
Nancy H
NH
Martins
Thomas B
TB
Hill
Harry R
HR
D000328:Adult; D001774:Blood Chemical Analysis / Q000379:methods*; D016207:Cytokines / Q000032:analysis* / Q000097:blood / Q000378:metabolism*; D005312:Fetal Blood / Q000276:immunology / Q000378:metabolism; D005408:Flagellin / Q000494:pharmacology; D006801:Humans; D007113:Immunity, Innate / Q000502:physiology; D007118:Immunoassay / Q000379:methods; D007231:Infant, Newborn; D008024:Ligands; D055666:Lipopeptides / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D011070:Poly I-C / Q000494:pharmacology; D012698:Serologic Tests / Q000379:methods; D018417:Th1 Cells / Q000276:immunology / Q000378:metabolism; D018418:Th2 Cells / Q000276:immunology / Q000378:metabolism; D051193:Toll-Like Receptors / Q000819:agonists / Q000502:physiology*; D015054:Zymosan / Q000494:pharmacology
D016207:Cytokines; D008024:Ligands; D055666:Lipopeptides; D008070:Lipopolysaccharides; C508075:Pam(3)CSK(4) peptide; D051193:Toll-Like Receptors; D005408:Flagellin; D015054:Zymosan; D011070:Poly I-C