Vitamin D status modifies the response to indoor particulate matter in obese urban children with asthma

Publication date: Available online 11 February 2019

Source: The Journal of Allergy and Clinical Immunology: In Practice

Author(s): Sonali Bose, Gregory B. Diette, Han Woo, Kirsten Koehler, Karina Romero, Ana M. Rule, Barbara Detrick, Emily Brigham, Meredith C. McCormack, Nadia N. Hansel

Abstract

Background

Indoor fine particulate air pollution (PM_2.5) is linked to asthma morbidity; however, whether vitamin D status influences individual susceptibility to airborne exposures is unclear.

Objective

We aimed to determine if vitamin D modifies effects of indoor PM_2.5 upon asthma symptoms in urban children.

Methods

120 children aged 5-12 years with physician-diagnosed asthma were evaluated at baseline and every 3 months for 9 months. Indoor PM_2.5, serum 25-hydroxy vitamin D (25-OH D) levels and asthma symptoms were simultaneously assessed at each time point. Adjusting for confounders, generalized estimating equations assessed 3-way interaction effects of 25-OH D, obesity and PM upon asthma symptoms.

Results

Children were of mean (SD) age 9.7 (2.2) years, 36% were obese, and 95% self-reported black race. Mean (SD) PM_2.5 indoor exposure was 38.2 (42.9) μg/m³ and 25-OH D was 19.1 (7.5) ng/ml. Three-way interaction models demonstrated significantly greater PM_2.5-associated effects on daytime asthma symptoms only among obese children with low 25-OH D levels (OR_PM2.5=1.26,p =0.049 at vitamin D=15.5 ng/ml, increasingly stronger PM effects at levels<15.5 ng/ml). In homes with increased PM_2.5, higher 25-OH D was associated with decreased symptom odds (e.g., OR_{Vitamin D} = 0.87; p=0.049 at PM_2.5 = 52.5 μg/m³, increasingly protective effects >52.5 μg/m³) among obese children.

Conclusion

Among obese urban children with asthma, low individual 25-OH vitamin D enhanced adverse respiratory effects associated with indoor PM_2.5. In high PM_2.5 environments, 25-OH D was protective against asthma symptoms. Optimizing vitamin D status in children may help reduce asthma morbidity driven by indoor air pollution.

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