Low neonatal Toll-like receptor 4-mediated interleukin-10 production is associated with subsequent atopic dermatitis

Background Atopic dermatitis (AD) and respiratory syncytial virus lower respiratory tract infection (RSV LRTI) are common diseases during early life. Impaired Th1-cell polarizing Toll-like receptor (TLR) responses play an important role in the pathogenesis of both diseases. Neonatal TLR-mediated production of Th1-type cytokines is decreased at birth, but rapidly increases during the first month of life. Objective To determine whether decreased TLR-mediated production of Th1-polarizing cytokines, at the age of 1 month is associated with subsequent AD or RSV LRTI. Methods A prospective healthy birth cohort study was performed. Whole blood concentrations of innate immune cells and TLR-mediated cytokine responses were measured at the age of 1 month in 291 neonates. AD was determined by a physician questionnaire at the age of 1 year and RSV LRTI was defined as parent-reported respiratory symptoms and presence of RSV RNA in a nose-throat specimen. Results Of participating neonates, 45 (15%) developed AD and 41 (14%) developed RSV LRTI. Risks of AD and RSV LRTI were not associated (v2, P = 1.00). AD was associated with decreased concentrations of basophils (7.6 vs. 14.0 9 10 6/mL, P = 0.002) and plasmacytoid dendritic cells (17.0 vs. 20.5 9 10 6/mL, P = 0.04), increased concentrations of NK-cells (79.7 vs. 45.1 9 10 6/mL, P = 0.03), and twofold lower TLR4-mediated IL-10 production (P = 0.001). In contrast, RSV LRTI was associated neither with neonatal concentrations of innate immune cells, nor with TLR-mediated TNF-a, IL-12p70, IL-10 or IFN-a production. Conclusions and Clinical Relevance Atopic dermatitis, but not RSV LRTI, is associated with distinct pre-symptomatic differences in the innate immune system. We hypothesize that decreased neonatal IL-10-mediated immune regulation during early life might play a causal role in the initiation of AD.