Dose-effect relationship between serum polycyclic aromatic hydrocarbon adducts and leukocyte miR-638 in children exposed to ambient particulate matter

Background Exposure to particulate matter (PM) and polycyclic aromatic hydrocarbon composition can influence the expression of microRNA (miRNA) in leukocytes, which can induce oxidative stress, inflammatory response, and immune response. Children are sensitive to PM exposure, but there are few studies on the changes of miRNA in their peripheral blood in association with PM.

Objective The study aims to investigate potential dose-effect relationship between polycyclic aromatic hydrocarbon-albumin adducts in serum and miR-638 in leukocytes among children exposed to PM.

Methods A total of 162 children from boarding schools in an area with high PM exposure were selected as the high-PM exposure group, while 108 children from boarding schools in an area with low PM exposure were as the low-PM exposure group. The annual levels of PM_2.5 and PM₁₀ in the two areas were collected. The concentrations of PM_2.5 and benzoapyrene (BaP) in PM_2.5 on campus were determined at fixed monitoring sites. Tobacco exposure was assessed according to the concentration of urinary cotinine. The long-term exposure level of PAH was assessed by serum benzoapyrene diol epoxide (BPDE)-albumin adducts. The expression of miR-638 was detected by real-time quantitative PCR. Linear regression model was used to analyze the differences in miR-638 among different subgroups and the dose-effect relationship between serum BPDE-albumin adducts and miR-638 level in leukocytes.

Results The concentrations of annual PM_2.5 (79.00μg·m^-3), annual PM₁₀ (175.00μg·m^-3), and serum BPDE-albumin adducts (82.41±20.12) nmol·L^-1 in the high-PM exposure group were higher than those in the low-PM exposure group 46.00 μg·m^-3, 82.00 μg·m^-3, (64.84±14.26) nmol·L^-1(P < 0.001). PM_2.5 level was positively correlated with BaP level (r=0.691, P < 0.001). The level of leukocyte miR-638 M (P₂₅, P₇₅): 1.00(0.62, 1.53) in the high-PM exposure group was significantly higher than that in the low-PM exposure M (P₂₅, P₇₅): 0.70 (0.47, 1.20) (P < 0.05). After adjusting for age, sex, urinary cotinine, body mass index (BMI) z-scores, and white blood cell counts, the results of linear regression model showed that an interquartile range (IQR, 27.09 nmol·L^-1) increase in serum BPDE-albumin adducts was associated with 24.56% (P < 0.001) increment of miR-638 among children; an IQR (25.95 nmol·L^-1) increase in serum BPDE-albumin adducts was associated with 19.28%(P=0.003) increase of miR-638 in the high-PM exposure group. After stratification, with each IQR (27.34, 28.84, 24.74, 25.06 nmol·L^-1) increase of serum BPDE-albumin adducts, the expression levels of miR-638 increased by 20.60% (P=0.007) in boys, 34.57% (P=0.012) in girls, 26.89% (P < 0.001) in normal weight children, and 23.78% (P < 0.001) in the children without urinary cotinine detected.

Conclusion PAH components in PM could induce elevated miR-638 in leukocytes among selected school children. There is a significant dose-effect relationship between serum BPDE-albumin adducts and miR-638 in leukocytes.