[Spatiotemporal Distribution Characteristics of Air Pollution and Health Risks in Key Cities of China].

Based on the monitoring data of five pollutants in 168 key cities under air pollution prevention and control in China from 2015 to 2020, using the MAKESENS model and the aggregate risk index(ARI), this study quantitatively analyzed the spatial and temporal distribution characteristics of air pollution and health risks in China and the six urban agglomerations. The results showed that:① PM2.5 pollution was the most serious pollution in Chinese key cities. Only 15% of the cities' six-year average concentrations of PM2.5 reached the National Secondary Standard, followed by that of NO2; 77% of the cities' six-year average concentrations of NO2 reached the National Secondary Standard. The urban agglomerations of Beijing-Tianjin-Hebei and Fenwei plain had the most serious air pollution, and the six-year average concentrations of PM2.5, SO2, CO, and NO2 were higher than those of other urban agglomerations. ② The concentrations of PM2.5, SO2, CO, and NO2 in key cities of China showed a decreasing trend, whereas the concentration of O3 in other urban agglomerations showed an increasing trend, except in the Chengdu-Chongqing urban agglomeration. The concentration of SO2 in the urban agglomerations of Beijing-Tianjin-Hebei and Fenwei plain changed the most significantly. ③ The health risk of air pollution in the key cities of China generally showed a decreasing trend, with a sharp decline from 2017 to 2018, and the population exposed to extremely high risks dropped from 160 million to 32.54 million. The urban agglomeration in the middle reaches of the Yangtze River had the most significant decline in health risks, whereas the key cities in China faced higher health risks in spring and winter seasons. ④ The Beijing-Tianjin-Hebei and Fenwei plain urban agglomerations had the highest health risks, and the urban agglomeration in the middle reaches of the Yangtze River had the lowest; O3 gradually replaced PM2.5 as the main pollutant affecting the health risk. These results can provide a reference for evaluating the effectiveness of urban air pollution control in China during the 13th Five-Year Plan period.

Asthma susceptibility in prenatal nicotine-exposed mice attributed to ß-catenin increase during CD4+ T cell development.

Cigarette smoke is a common global environmental pollutant. Asthma, the most frequent allergic airway disease, is related to maternal exposure to cigarette smoke. Our previous studies demonstrated that prenatal exposure to nicotine (PNE), the major active product of smoking, impairs fetal thymopoiesis and CD4+ T cell development after birth. This study aimed to investigate whether PNE contributes to asthma susceptibility through CD4+ T cell development alterations. First, A PNE model was established by administering 3 mg/kg/day nicotine to maternal mice, and then an ovalbumin-induced asthma model was established in the offspring. Further, ß-catenin and downstream pathways were inhibited in vitro to confirm the molecular mechanisms underlying the phenotype observed during the in vivo phase. The results showed that PNE induced Th2 and Th17 biases at developmental checkpoints and aggravated asthma symptoms in the offspring. In fetuses, PNE up-regulated α7 nAChR, activated PI3K-AKT, promoted ß-catenin level increase, and established potential Th2- and Th17-biased gene expression patterns during thymopoiesis, which persisted after birth. Similar results were also observed in 1 µM nicotine-treated thymocytes in vitro. Moreover, inhibiting PI3K-AKT by LY294002 abrogated nicotine-mediated ß-catenin level increase and thymopoiesis abnormalities, and an α7 nAChR antagonist (α-btx) also reversed nicotine-induced PI3K-AKT activation. Our findings provide strong evidence that PNE is a risk factor for T cell deviation and postnatal asthma, and revealed that nicotine-induced ß-catenin level increase induces thymopoiesis abnormalities.

Augmented autophagy suppresses thymocytes development via Bcl10/p-p65 pathway in prenatal nicotine exposed fetal mice.

Tobacco smoke is a common global environmental pollutant. Maternal tobacco smoke/nicotine exposure has long-term toxic effects on immune organs. We previously found that prenatal nicotine exposure (PNE)-induced programmed immune diseases caused by fetal thymic hypoplasia, but the mechanism still unknown. Autophagy has important functions in maintaining thymopoiesis, whether autophagy was involved in PNE-inhibited fetal thymocytes development is also obscure. Therefore, this study aimed to investigate how nicotine changed the development of fetal thymocytes from the perspective of autophagy in vivo and in vitro. PNE model was established by 3 mg/kg nicotine administration in Balb/c mice from gestational day 9 to 18. The results showed that PNE reduced the percentage and absolute number of CD69-CD4+SP cells, suggesting a block of fetal thymocytes mature. PNE promoted autophagosome formation, autophagy related proteins (Beclin1, LC3I/II) expression, and upregulated α7 nAChR as well as AMPK phosphorylation in fetal thymus. Moreover, PNE promoted Bcl10 degradation via autophagy-mediated proteolysis and inhibited p65 activation, blocking the transition of thymocytes between the DP to SP stage. Further, primary thymocytes were treated with nicotine in vitro and showed induced autophagy in a dose- and time-dependent manner. In addition, nicotine-inhibited CD69-CD4+SP cells and the Bcl10/p-p65 pathway have been reversed by an autophagy inhibitor. The α7 nAChR specific antagonist abrogated nicotine-induced AMPK phosphorylation and autophagy initiation. In conclusion, our findings showed that PNE repressed the Bcl10/p-p65 development pathway of CD4+SP cells by triggering autophagy, and illuminated the developmental origin mechanism of programmed immune diseases in PNE offspring.

Attenuated cholesterol metabolism pathway suppresses regulatory T cell development in prenatal nicotine exposed female mice.

The recession of regulatory T cells (Tregs) contributes to development of autoimmune disease. Our previous study suggested that prenatal nicotine exposure (PNE) inhibited Tregs frequency in offspring, but the mechanisms are still uncertain. This study aimed to explore the molecular mechanisms of PNE-induced Tregs inhibition from the perspective of cellular cholesterol homeostasis both in vivo and in vitro. PNE mice model were established by 3 mg/kg/d nicotine administration in Balb/c strain from gestational day (GD) 9 to GD 18. The results showed that PNE significantly decreased thymic Tregs frequency in neonatal offspring. The activation of mTOR and downregulation of p-STAT5/Foxp3 pathway of Tregs were observed in PNE offspring. Mechanism study found that PNE elevated ATP-binding cassette transporter G1 (ABCG1) expression and decreased intracellular cholesterol content of Tregs in offspring, indicating impaired intracellular cholesterol homeostasis. Similar results were observed in 1 µM nicotine-treated primary thymocytes in vitro. Further, cholesterol-replenishment can abrogate nicotine-induced mTOR activation and the following suppression of p-STAT5/Foxp3 pathway and Tregs frequency. In addition, Abcg1 siRNA transfection can partly reverse the nicotine-decreased intracellular cholesterol content and cell frequency of Tregs. In conclusion, this study showed that PNE could suppress Tregs development in female mice by up-regulating ABCG1-dependent cholesterol efflux, and suggested that PNE-induced thymic Tregs recession of offspring at early life was the developmental origin mechanism of immune dysfunction in later life.

UV-B-induced oxidative damage and protective role of exopolysaccharides in desert cyanobacterium Microcoleus vaginatus.

UV-B-induced oxidative damage and the protective effect of exopolysaccharides (EPS) in Microcoleus vaginatus, a cyanobacterium isolated from desert crust, were investigated. After being irradiated with UV-B radiation, photosynthetic activity (Fv/Fm), cellular total carbohydrates, EPS and sucrose production of irradiated cells decreased, while reducing sugars, reactive oxygen species (ROS) generation, malondialdehyde (MDA) production and DNA strand breaks increased significantly. However, when pretreated with 100 mg/L exogenous EPS, EPS production in the culture medium of UV-B stressed cells decreased significantly; Fv/Fm, cellular total carbohydrates, reducing sugars and sucrose synthase (SS) activity of irradiated cells increased significantly, while ROS generation, MDA production and DNA strand breaks of irradiated cells decreased significantly. The results suggested that EPS exhibited a significant protective effect on DNA strand breaks and lipid peroxidation by effectively eliminating ROS induced by UV-B radiation in M. vaginatus.

[Cell-surface hydrophobicity and degradation characteristics of hydrophobic hydrocarbon degrading bacteria].

Three high efficient hydrocarbon degrading bacteria named HDB-1, HDB-2, HDB-3 were separated from the oil contaminant soil. This paper studied on the cell-surface hydrophobicity of these three bacteria and environment influence factor by MATH,and the results show that the xylene-water two-phase system is suitable for studying the cell-surface hydrophobicity of three bacteria; the cell-surface hydrophobicities of HDB-1, HDB-2 and HDB-3 are respectively 68.8%, 57.4% and 64.1%; the hydrophobicity changed with the difference of cultivation and time,carbon source, temperature and pH value; the removal ratio of 1 000 mg/L oil content for 6 day can reach 91.6%, 64.5% and 79.8%. The hydrophobicity is related definitely with the degradation of the organic pollutant, and the degradation rate of hydrophobic organic by the bacteria of high hydrophobicity is quicker than that by the bacteria of low hydrophobicity.