Nasal oxidative stress mediating the effects of colder temperature exposure on pediatric asthma symptoms

BackgroundColder temperature exposure is a known trigger for pediatric asthma exacerbation. The induction of oxidative stress is a known pathophysiologic pathway for asthma exacerbation. However, the role of oxidative stress in linking colder temperature exposure and worsened pediatric asthma symptoms is poorly understood.MethodsIn a panel study involving 43 children with asthma, aged 5-13 years old, each child was visited 4 times with a 2-week interval. At each visit, nasal fluid, urine, and saliva samples were obtained and measured for biomarkers of oxidative stress in the nasal cavity (nasal malondialdehyde [MDA]), the circulatory system (urinary MDA), and the oral cavity (salivary MDA). Childhood Asthma-Control Test (CACT) was used to assess asthma symptoms.ResultsWhen ambient daily-average temperature ranged from 7 to 18 degrees C, a 2 degrees C decrement in personal temperature exposures were significantly associated with higher nasal MDA and urinary MDA concentrations by 47-77% and 6-14%, respectively. We estimated that, of the decrease in child-reported CACT scores (indicating worsened asthma symptoms and asthma control) associated with colder temperature exposure, 14-57% were mediated by nasal MDA.ConclusionThese results suggest a plausible pathway that colder temperature exposure worsens pediatric asthma symptoms partly via inducing nasal oxidative stress.ImpactThe role of oxidative stress in linking colder temperature exposure and worsened asthma symptoms is still poorly understood.Lower temperature exposure in a colder season was associated with higher nasal and systemic oxidative stress in children with asthma.Nasal MDA, a biomarker of nasal oxidative stress, mediated the associations between colder temperature exposures and pediatric asthma symptoms.The results firstly suggest a plausible pathway that colder temperature exposure worsens pediatric asthma symptoms partly via inducing oxidative stress in the nasal cavity.