BackgroundAlthough rhinovirus infection is associated with increased risks of acute and chronic respiratory outcomes during childhood compared with respiratory syncytial virus (RSV), the underlying mechanisms remain unclear. We aimed to determine the differences in nasal airway microRNA profiles and their downstream effects between infants with rhinovirus and RSV bronchiolitis.MethodsAs part of a multicenter cohort study of infants hospitalized for bronchiolitis, we examined nasal samples obtained from 16 infants with rhinovirus and 16 infants with RSV. We tested nasal airway samples using microarrays to profile global microRNA expression and determine the predicted regulation of targeted transcripts. We also measured gene expression and cytokines for NFkappaB pathway components.ResultsBetween the virus groups, 386 microRNAs were differentially expressed (false discovery rate (FDR)<0.05). In infants with rhinovirus, the NFkappaB pathway was highly ranked as a predicted target for these differentially expressed microRNAs compared with RSV. Pathway analysis using measured mRNA expression data validated that rhinovirus infection had upregulation of NFkappaB family (RelA and NFkappaB2) and downregulation of inhibitor kappaB family. Infants with rhinovirus had higher levels of NFkappaB-induced type-2 cytokines (IL-10 and IL-13; FDR<0.01).ConclusionIn infants with bronchiolitis, rhinovirus and RSV infections had different nasal airway microRNA profiles associated with NFkappaB signaling.