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Epidemiological studies have shown that exposure to ambient fine particulate matter (PM ) is associated with respiratory diseases. Lung inflammation is a central feature of many pulmonary diseases, which can be induced by PM exposure. However, the mechanisms underlying PM -induced lung inflammation remain unclear. To characterize the role of epidermal growth factor receptor (EGFR) and inflammasome in PM -induced lung inflammation in mice, 30 BALB/c mice were intrabroncheally instilled with saline and PM suspension (4.0 mg/kg b.w.) for 5 consecutive days, respectively. Bronchoalveolar lavage (BAL) was conducted and BAL fluid (BALF) was collected. The levels of reactive oxygen species (ROS), inducible nitric oxide synthase (iNOS), epidermal growth factor (EGF), CXCL1, interleukin (IL)-1β, and IL-18 in BALF were determined using ELISA. mRNA levels of IL-6, IL-1β, IL-18, CXCL1, IL-10, NLRP3, Caspase-1, and NLRP12 in lung tissues were determined by RT-PCR. Phospho-EGFR (Tyr1068) and phospho-Akt (Thr308) in lung tissues were examined using immunohistochemical staining and Western blotting, respectively. Protein levels of Caspase-1, NLRP3, NF-κB-p52/p100, and NF-κB-p65 in bronchial epithelium were examined using immunohistochemical staining. It was shown that PM exposure induced lung inflammation. Levels of total protein, ROS, iNOS, EGF, and CXCL1 and cell number in the BALF of mice exposed to PM were markedly elevated relative to the control. mRNA levels of CXCL1, IL-1β, and IL-18 in lung tissues of PM -exposed mice were increased in comparison with the control. However, level of NLRP12 mRNA in lung tissues of PM -exposed mice was reduced. Phospho-EGFR (Tyr1068) and phospho-Akt (Thr308) levels in the lungs of PM -instilled mice were higher than those in the lungs of the control. The protein levels of NF-κB-p52/p100 and NF-κB-p65 in bronchial epithelium of PM -exposed mice were also increased compared with the control. This study suggests that EGF-EGFR-Akt-NF-κB signaling and NLRP12 inflammasome may be associated with PM -induced lung inflammation in mice. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1121-1134, 2017.

BackgroundIn soils and sediments, manganese oxides and oxygen usually participate in the oxidation of ferrous ions. There is limited information concerning the interaction process and mechanisms of ferrous ions and manganese oxides. The influence of air (oxygen) on reaction process and kinetics has been seldom studied. Because redox reactions usually occur in open systems, the participation of air needs to be further investigated.ResultsTo simulate this process, hexagonal birnessite was prepared and used to oxidize ferrous ions in anoxic and aerobic aqueous systems. The influence of pH, concentration, temperature, and presence of air (oxygen) on the redox rate was studied. The redox reaction of birnessite and ferrous ions was accompanied by the release of Mn2+ and K+ ions, a significant decrease in Fe2+ concentration, and the formation of mixed lepidocrocite and goethite during the initial stage. Lepidocrocite did not completely transform into goethite under anoxic condition with pH about 5.5 within 30 days. Fe2+ exhibited much higher catalytic activity than Mn2+ during the transformation from amorphous Fe(III)-hydroxide to lepidocrocite and goethite under anoxic conditions. The release rates of Mn2+ were compared to estimate the redox rates of birnessite and Fe2+ under different conditions.ConclusionsRedox rate was found to be controlled by chemical reaction, and increased with increasing Fe2+ concentration, pH, and temperature. The formation of ferric (hydr)oxides precipitate inhibited the further reduction of birnessite. The presence of air accelerated the oxidation of Fe2+ to ferric oxides and facilitated the chemical stability of birnessite, which was not completely reduced and dissolved after 18 days. As for the oxidation of aqueous ferrous ions by oxygen in air, low and high pHs facilitated the formation of goethite and lepidocrocite, respectively. The experimental results illustrated the single and combined effects of manganese oxide and air on the transformation of Fe2+ to ferric oxides.Graphical abstract:Lepidocrocite and goethite were formed during the interaction of ferrous ion and birnessite at pH 4-7. Redox rate was controlled by the adsorption of Fe2+ on the surface of birnessite. The presence of air (oxygen) accelerated the oxidation of Fe2+ to ferric oxides and facilitated the chemical stability of birnessite

The base-free aerobic oxidation of 5-hydroxymethylfurfural (HMF) in water to 2,5-furandicarboxylic acid (FDCA) is a sustainable upgrading process for cellulosic carbohydrates. A mesoporous NiO-supported Pt nanoparticle (ca. 3 nm) catalyst was reported, which can achieve 100% selectivity to FDCA at a full conversion of HMF without the assistance of any base under mild conditions, that is, 100 °C, 10 bar O2, and 12 h. The catalyst efficiency in terms of productivity reached 22.2 molFDCA molPt –1 h–1, which is the highest value among all the supported Pt catalysts to date in literature. Moreover, the Pt/NiO catalyst showed a remarkably stable and reusable performance during five consecutive cycling. X-ray diffraction, N2 physisorption, transmission electron microscopy, X-ray photoelectron spectroscopy, CO-adsorbed diffuse reflectance Fourier transform infrared spectroscopy, temperature-programed reduction of hydrogen, temperature-programed desorption of oxygen, and electron paramagnetic resonance techniques were used to comprehensively analyze the catalysts. It was disclosed that tailoring the reactive oxygen species in NiO is an effective way to control the initial reaction rate of HMF as well as the derived intermediates (i.e., a reflection of product distribution). This can be manipulated by varying the aging temperature during the preparation of NiO; thus, the role of different oxygen species (i.e., Oads. and Olatt.) in NiO was clarified. The interaction between the metallic Pt active sites and the mobile oxygen species was found to be critical to the excellent catalytic performance.