Comparative responses of paediatric airway epithelium to viral and allergen insult

Asthma affects over a million children in the UK. Early age viral infection, allergen sensitization, atopy and genetic predisposition increases the likelihood of developing asthma. Our aim is to understand the consequences of allergen exposure (house-dust mite; HDM) and/or RSV infection on innate immune responses, cytopathogenesis and virus replication in paediatric airway epithelium. Well-differentiated primary paediatric nasal epithelial cell (WD-PNEC) cultures derived from newborn or pre-school children were infected with RSV before or after stimulation with HDM. Virus growth kinetics, cytopathology and innate immune responses were analysed. HDM pre-treatment did not affect the culture integrity or RSV growth. Preliminary RT-qPCR analysis revealed upregulation of irf9 in RSV infected/HDM treated and HDM pre-treated/RSV infected cultures at 24 and 96 h post-infection (hpi). Isg15 was also upregulated in HDM pre-treated/RSV infected cultures at 24 hpi in newborns only. At 96 hpi, irf9, isg15, ifi6, duox2 and duoxA2 were upregulated in RSV infected cultures. Surprisingly, HDM treatment alone did not induce any significant upregulation of these genes compare to untreated/uninfected controls. However, data from more donors will be required to confirm these preliminary data. IL-29/IFNλ1 secretion was also significantly reduced following HDM pre-treatment of RSV infected cultures, while there was a trend towards reduced IL-6 secretion. These results suggest that HDM exposure modulates the innate immune responses to RSV infection of airway epithelium. The preliminary data are consistent with our over-arching hypothesis that our model of aeroallergen exposure and viral infection of airway epithelium will help elucidate mechanisms by which pre-school wheeze develops.