The relationship between exposure to polycyclic aromatic hydrocarbons and adult atopic dermatitis

Background: Polycyclic aromatic hydrocarbons are one of the major pathogenic components in air pollution. Previous studies have demonstrated an association between air pollution and atopic dermatitis. Objective: We sought to explore the relationship between polycyclic aromatic hydrocarbons exposure and adult atopic dermatitis. Methods: We prospectively recruited 23 adult patients with atopic dermatitis and 11 healthy controls. Plasma levels of inflammatory cytokines were determined using enzyme-linked immunosorbent assay. Expression levels of aryl hydrocarbon receptor, which mediates the effect of polycyclic aromatic hydrocarbons, and cytokines in peripheral blood nuclear cells (PBMCs) were measured using reverse transcription polymerase chain reaction. Urine levels of 16 polycyclic aromatic hydrocarbon metabolites were determined by gas chromatography-tandem mass spectrometry. Results: Patients with atopic dermatitis had lower levels of interleukin (IL)-5 and IL-23, and lower PBMC messenger RNA expression levels of interferon-γ than the healthy controls. Plasma levels of IL-22 were moderately and positively associated with the SCORAD index. Creatinine-corrected urine levels of 9-hydroxyfluorene and 2-hydroxyphenanthrene were elevated in the atopic dermatitis group. However the difference was not statistically significant after Bonferroni correction. Conclusion: Our results demonstrated that the polycyclic aromatic hydrocarbons fluorene and phenanthrene are potentially associated with the pathogenesis of atopic dermatitis in adults.