Selenium Deficiency Caused Fibrosis as an Oxidative Stress-induced Inflammatory Injury in the Lungs of Mice.

Selenium (Se) is a vital trace element in the regulation of inflammation and antioxidant reactions in both animals and humans. Se deficiency is rapidly affecting lung function. The present study investigated the molecular mechanism of Se deficiency aggravates reactive oxygen species (ROS)-induced inflammation, leading to fibrosis in lung. Mice fed with different concentrations of Se to establish the model. In the Se-deficient group, the ROS and malondialdehyde (MDA) was increased, and the activities of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), total antioxidant capacity (T-AOC), and catalase (CAT) reduced. The histopathological observation showed that Se deficiency lead to lung texture damage with varying degrees of degeneration, necrosis, shedding of some alveolar epithelial cells, and inflammatory cell infiltration. Immunohistochemistry showed that the expression of α-smooth muscle actin (α-SMA) increased. The fibrosis index was verified with Sirius red staining. The ELISA and qPCR results showed that the inflammatory cytokines (TNF-α and IL-1ß) and ECM (collagen I, collagen IV, fibronectin, and laminin) were increased with ROS increasing, which was induced by Se deficiency. The results displayed that oxidative stress with Se deficiency led to an increase in tissue inhibitors of metalloproteinase (TIMPs), but a decrease in matrix metalloproteinases (MMPs). All the results indicated that Se deficiency induced excessive ROS accumulation to generate inflammation, which disrupted ECM homeostasis and aggravated fibrosis in the lung.

Vertical distribution and environmental significance of PAHs in soil profiles in Beijing, China.

Vertical distribution of both the concentration and composition of polycyclic aromatic hydrocarbons (PAHs) in ten profiles in Beijing has been investigated. The results showed that PAH concentrations and compositions in topsoil from different sampling sites were different. PAH concentrations were much higher in topsoil of the investigated urban area, industrial region, and paddy field with wastewater irrigation than in other areas. Moreover, PAH concentrations in topsoil were much higher than those at greater depth, where the concentrations were relatively consistent in most soil profiles. The fingerprints of PAHs in the samples from topsoil (0-30 cm) in the same profiles were similar and were obviously different from those at greater depth, suggesting that PAH sources were consistent in topsoil samples and were discriminating between topsoil and deeper soils. PAHs in topsoil mainly arose from mixed sources of combustion of liquid fuel, coal, and/or wood, as well as wastewater irrigation, while those at greater depth were derived from soil genesis and the process of soil formation.