INTRODUCTION
Previous studies reported that exposures to environmental pollutants are
responsible for the increasing prevalence of allergic
diseases.1,2 Here, we focused on phthalates, a group
of chemicals commonly used as plasticizers that commonly have higher
concentrations in children than adults.3 Phthalates
can have adverse effects on the respiratory and immunological systems.
Epidemiological studies reported positive associations between
indicators of phthalate exposure and risk of asthma, and allergic
diseases.4,5 Other studies reported that phthalates
also adversely affect pulmonary functions.6,7Experimental studies demonstrated that exposure to phthalates increased
the levels of T helper 2 (Th2) cells and cytokines, and also increased
airway inflammation.8,9 Several clinical studies found
an association between phthalate exposure and fractional exhaled nitric
oxide (FeNO).5,8 The immunological mechanisms by which
phthalate exposure leads to asthma and disruptions of lung function and
airway inflammation are unknown. In addition, few studies have examined
the association of phthalate exposure with allergic inflammation and
lung function.
Recent studies identified periostin and chitinase-like proteins as
biomarkers of asthma. Periostin promotes chronic allergic inflammation
in response to Th2-associated cytokines by inducing proinflammatory
cytokines.10 Chitinase-3-like protein 1, also known as
YKL-40, is a glycoprotein secreted by various cell types, including
macrophages, neutrophils, and airway epithelial
cells.11 However, little is known about the levels or
function of periostin and YKL-40 following exposure to environmental
pollutants or other chemicals. We hypothesized that phthalate exposure
may alter the serum levels of periostin and YKL-40.
Our primary objective was to determine the associations between
phthalate exposure and pulmonary functions in a population-based sample
of randomly selected sixth-grade students from 11 elementary schools in
Korea. Our secondary objective was to examine the potential role of
periostin and YKL-40 in mediating the relationship between phthalate
exposure and airway dysfunction.