IL-17A expression in the adenoid tissue from children with sleep disordered breathing and its association with pneumococcal carriage

Tonsil and adenoid-tissue hypertrophy (AH) is the most common cause of pediatric sleep-disordered breathing (SDB), with AH possibly initiated by repeated exposure to infectious agents or allergens. Here, we evaluated IL-17A activity in adenoid tissue from children with SDB and its association with AH and pneumococcal carriage. Thirty-five children (aged 3–12 years) with SDB and receiving adenoidectomy and tonsillectomy were enrolled. During surgery, nasopharyngeal carriage was determined by bacterial culture and multiplex PCR via nasopharyngeal swab, and adenoid samples were collected. IL-17A and associated cytokine expression was evaluated by real-time PCR and western blotting. The mRNA analysis showed that IL-17A level, IL-17A:IL-10 ratio, and RAR-related orphan receptor-γt:forkhead box P3 ratio were significantly higher in adenoid tissues with AH, as were IL-17A level and IL-17A:IL-10 ratio in adenoid tissues with pneumococcal carriage. Additionally, pneumococcal carriage was more common in nasopharyngeal adenoids from patients without AH than those with AH. IL-17A was upregulated in adenoid tissues from patients with AH and with pneumococcal carriage. These results suggested that pneumococcal carriage initiates an IL-17A-mediated immune response in nasopharyngeal adenoids, which might be associated with AH in patients with SDB.