Expression of HMGB1 in maternal exposure to fine particulate air pollution induces lung injury in rat offspring assessed with micro-CT

Abstract Objectives Maternal particulate matter with less than 2.5 μm in diameter (PM2.5) is associated with an increased risk for acute lower respiratory infections and allergic airway inflammation; however, its effect on the developing lung remains unclear. The aim of this study is to determine the effect of maternal PM2.5 during pregnancy on lung development in offspring. Methods Timed pregnant Sprague-Dawley rats were treated with PM2.5 (0.1, 0.5, 2.5, or 7.5 mg/kg) once every 3 days from day 0–18 of pregnancy and delivered at term. Lungs were obtained on postnatal day 0, the structure of the lung was analyzed by quantitative micro-computed tomography (CT) and the levels of proinflammatory cytokines were analyzed using enzyme-linked immunosorbent assay (ELISA). The expression of high mobility group box-1 (HMGB1) was also detected by immunohistochemistry, Western blotting, and quantitative RT-PCR. Results Ground-glass opacity and high-density volumes in CT slice images of maternal PM2.5-exposure rats were observed. The concentrations of IL-1, IL-6 and TNF-α were significantly increased by 2.36-, 3.91- and 4.36-fold, respectively, in the rats of the PM-7.5 group compared with the rats in the control group. The PM2.5-treated rats showed a significant upregulated expression of HMGB1 in lungs. Conclusions PM2.5 exposure during pregnancy results in lung inflammation in offspring mediated by increased HMGB1 expression, followed by upregulated IL-1, IL-6 and TNF-α secretions, which may contribute to the development of inflammatory lung diseases in later life.