Dysfunctional neutrophil type 1 interferon responses in preschool children with recurrent wheezing and IL-4–mediated aeroallergen sensitization

BackgroundThe innate mechanisms associated with viral exacerbations in preschool children with recurrent wheezing are not understood. ObjectiveWe assessed differential gene expression in blood neutrophils from preschool children with recurrent wheezing, stratified by aeroallergen sensitization, at baseline and after exposure to polyinosinic-polycytidylic acid (poly(I:C)).We also examined whether poly(I:C)-stimulated blood neutrophils influenced airway epithelial gene expression. MethodsBlood neutrophils were purified and cultured overnight with poly(I:C) and underwent nextgeneration sequencing with Reactome pathway analysis.Primary human small airway epithelial cells were treated with poly(I:C)-treated neutrophil culture supernatants and were analyzed for Type 1 interferon gene expression with a targeted array.Symptoms and exacerbations were assessed in participants over 12 months. Results 436genes were differently expressed in neutrophils from children with versus without aeroallergen sensitization at baseline, with significant downregulation of Type 1 interferons.These Type 1 interferons were significantly upregulated in sensitized children after poly(I:C) stimulation.Confirmatory experiments demonstrated similar upregulation of Type 1 interferons in IL-4 treated neutrophils stimulated with poly(I:C).Poly(I:C)-treated neutrophil supernatants from children with aeroallergen sensitization also induced a Type 1 interferon response in epithelial cells.Children with aeroallergen sensitization also had higher symptom scores during J o u r n a l P r e -p r o o f exacerbations and these symptom differences persisted for three days after prednisolone treatment.Conclusions Type 1 interferon responses are dysregulated in preschool children with aeroallergen sensitization, which is in turn associated with exacerbation severity.Given the importance of Type 1 interferon signaling in viral resolution, additional studies of neutrophil Type 1 interferon responses are needed in this population.J o u r n a l P r e -p r o o f Key Messages • Preschool children with recurrent wheezing and aeroallergen sensitization, compared to children without aeroallergen sensitization, have impairment of Type 1 interferons at baseline, yet robust Type 1 interferon responses after viral stimulation, that may be due to increased circulating IL-4 concentrations.• Poly(I:C)-stimulated blood neutrophils from children with aeroallergen sensitization also increased Type 1 interferon responses in primary human small airway epithelial cells.• Children with aeroallergen sensitization also had more severe and prolonged symptoms during acute exacerbations.Together, these findings suggest that neutrophil Type 1 interferon responses are dysregulated in preschool children with recurrent wheezing and aeroallergen sensitization and could contribute to exacerbation severity in these children.