Published Online: May 24, 2016
Asthma and allergies are major public health issues and affect more than 300 million people worldwide. There is some evidence that Traffic Related Air Pollution (TRAP) is related to asthma and poor lung function however results have been inconsistent. This suggests that genetic variation in the toxin-metabolism pathway may modify response to TRAP and hence subsequent risk of allergy and poorer lung heath. To explore this further Bowatte and colleagues examined how polymorphisms in the Glutathione S-Transferase (GST) genes may modify the association between TRAP exposure and respiratory diseases and allergy.
In a recent publication by Dharmage and colleagues in The Journal of Allergy and Clinical Immunology (JACI) has analyzed data from the Tasmanian Longitudinal Health Study (TAHS), a population-based study started in 1968 and followed until middle-age. The analysis presented in the current manuscript includes data from the follow-up when the participants were aged 45years. The study of over 1,300 people included a clinical study with the collection of questionnaires, lung function measurements, skin prick tests for allergy and a blood sample for genotyping. Participants were genotyped for polymorphisms in the Glutathione S-Transferase Mu1 (GSTM1), Theta1 (GSTT1) and Pi1 (GSTP1) genes. TRAP exposure was assigned based on the study participant’s geocoded residential address. Two measures of TRAP were assigned, one as proximity to the nearest major road and the second as mean annual nitrogen dioxide (NO2) exposure from a satellite based model.
The researchers observed both NO2 exposure and living less than 200m from a major road to increase the risk of allergic sensitization to common aero-allergens and wheeze. For example, an increase of 2.2 parts per billion (ppb) in mean annual NO2 exposure increased the risk of sensitization by nearly 14 percent. Particularly NO2 exposure was associated with increased risk of allergic asthma. Living less than 200 m from a major road was associated with lower lung function levels in this group of middle age adults. Additionally, having the GSTT1 null allele increased the risk of sensitization associated with TRAP exposure. Similarly having GSTT1 null allele modified the risk of reduced lung function associated with TRAP exposure.
The findings demonstrate that in a middle-aged population TRAP exposure is associated with an increased risk of allergen sensitization and poorer lung function. The study also found that these risks were significantly higher for individuals carrying the GSTT1 null mutation.
The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.