Effects of 1,4-naphthoquinone aged carbon black particles on the cell membrane of human bronchial epithelium

Toxicological Effects of Secondary Air Pollutants

Secondary air pollutants, originating from gaseous pollutants and primary particulate matter emitted by natural sources and human activities, undergo complex atmospheric chemical reactions and multiphase processes. Secondary gaseous pollutants represented by ozone and secondary particulate matter, including sulfates, nitrates, ammonium salts, and secondary organic aerosols, are formed in the atmosphere, affecting air quality and human health. This paper summarizes the formation pathways and mechanisms of important atmospheric secondary pollutants. Meanwhile, different secondary pollutants' toxicological effects and corresponding health risks are evaluated. Studies have shown that secondary pollutants are generally more toxic than primary ones. However, due to their diverse source and complex generation mechanism, the study of the toxicological effects of secondary pollutants is still in its early stages. Therefore, this paper first introduces the formation mechanism of secondary gaseous pollutants and focuses mainly on ozone's toxicological effects. In terms of particulate matter, secondary inorganic and organic particulate matters are summarized separately, then the contribution and toxicological effects of secondary components formed from primary carbonaceous aerosols are discussed. Finally, secondary pollutants generated in the indoor environment are briefly introduced. Overall, a comprehensive review of secondary air pollutants may shed light on the future toxicological and health effects research of secondary air pollutants.

Exploration of potential mechanism of interleukin-33 up-regulation caused by 1,4-naphthoquinone black carbon in RAW264.7 cells

BACKGROUND

As air pollution has been paid more attention to by public in recent years, effects and mechanism in particulate matter-triggered health problems become a focus of research. Lysosomes and mitochondria play an important role in regulation of inflammation. Interleukin-33 (IL-33) has been proved to promote inflammation in our previous studies. In this research, macrophage cell line RAW264.7 was used to explore the potential mechanism of upregulation of IL-33 induced by 1,4-naphthoquinone black carbon (1,4-NQ-BC), and to explore changes of lysosomes and mitochondria during the process.

RESULTS

50 μg/mL 1,4-NQ-BC exposure for 24 h dramatically increased expression of IL-33 in RAW264.7 cells. Lysosomal membrane permeability was damaged by 1,4-NQ-BC treatment, and higher mitochondrial membrane potential and ROS level were induced by 1,4-NQ-BC. The results of proteomics suggested that expression of ferritin light chain was increased after cells were challenged with 1,4-NQ-BC, and it was verified by Western blot. Meanwhile, expressions of p62 and LC3B-II were increased by 50 μg/mL 1,4-NQ-BC in RAW264.7 cells. Ultimately, expression of IL-33 could return to same level as control in cells treated with 50 μg/mL 1,4-NQ-BC and 50 μM deferoxamine combined.

CONCLUSIONS

1,4-NQ-BC induces IL-33 upregulation in RAW264.7 cells, and it is responsible for higher lysosomal membrane permeability and ROS level, lower mitochondrial membrane potential, and inhibition of autophagy. Ferritin light chain possibly plays an important role in the upregulation of IL-33 evoked by 1,4-NQ-BC.

Early structural and functional changes in Baikal Sculpin gills exposed to suspended soot microparticles in experiment

The toxic influence of soot microparticles on terrestrial organisms has been well studied, although there is scarce data on how microparticles could affect hydrobionts. We performed a first-ever study of the short-term (5 days) impact of furnace soot (0.005 g/L) on the structural and functional features of gill cells in the Baikal Sculpin species Paracottus knerii, Dybowski, 1874. The soot samples used in the experiment were composed of small (10-100 nm) particles and larger (up to 20 μm) aggregates. The dominant fractions of the polycyclic aromatic hydrocarbons of these microparticles were phenanthrene, fluoranthene, pyrene, benzo[a]anthracene, chrysene, benzofluoranthenes, benzopyrenes, indeno[1,2,3-c,d]pyrenes, and benzo[ghi]perylene. Trace element analysis of the soot detected the presence of C, S, Si, Al, Ca, K, Mg, P, and Fe. The gill condition was assessed with electron scanning, transmission, and laser confocal microscopy. Soot induces degenerative changes in the macrostructure and surface of secondary lamellae and increases mucus production in fish gills. A decrease in mitochondrial activity, an increase in reactive oxygen species production, and an increase in the frequency of programmed cell death in gill epithelium were observed under the influence of soot. In chloride cells, an induction of macroautophagy was detected. In general, the changes in fish gills after the short-term influence of soot microparticles indicate the stress of respiratory and osmotic regulation systems in fish. The data obtained are important for forming a coherent picture of the impact of soot on hydrobionts and for developing bioindication methods for evaluating the risks of their influence on aquatic ecosystems.

Low-dose combined exposure of carboxylated black carbon and heavy metal lead induced potentiation of oxidative stress, DNA damage, inflammation, and apoptosis in BEAS-2B cells

Black carbon (BC) and heavy metal lead (Pb), as typical components of atmospheric PM_2.5, have been shown to cause a variety of adverse health effects. However, co-exposure to BC and Pb may induce pulmonary damage by aggravating toxicity via an unknown mechanism. This study aimed to investigate the combined toxicity of carboxylated black carbon (c-BC) and lead acetate (Pb) on human bronchial epithelial cells (BEAS-2B) at the no-observed-adverse-effect level (NOAEL). Cells were exposed to c-BC (6.25 μg/mL) and Pb (4 μg/mL) alone or their combination, and their combined toxicity was investigated by focusing on cell viability, oxidative stress, DNA damage, mitochondrial membrane potential (MMP), apoptosis, and cellular inflammation. Factorial analyses were also used to determine the potential interactions between c-BC and Pb. The results suggested that the combination of c-BC and Pb could significantly increase the production of reactive oxygen species (ROS), malondialdehyde (MDA), and lactate dehydrogenase leakage (LDH) and decrease the activities of glutathione (GSH) and superoxide dismutase (SOD). The excessive oxidative stress could increase the levels of inflammatory cytokine IL-6 and TNF-α, and induce oxidative DNA damage and dissipation of MMP. Moreover, the results also suggested that the combined group could enhance the cellular apoptotic rate and the activation of apoptotic markers like caspase-3, caspase-8, and caspase-9. The factorial analysis further demonstrated that synergistic interaction was responsible for the combined toxicity of c-BC and Pb co-exposure. Most noticeably, the co-exposure of c-BC and Pb could induce some unexpected toxicity, even beyond the known toxicities of the individual compounds in BEAS-2B cells at the NOAEL.

An update on immunologic mechanisms in the respiratory mucosa in response to air pollutants

Every day, we breathe in more than 10,000 L of air that contains a variety of air pollutants that can pose negative consequences to lung health. The respiratory mucosa formed by the airway epithelium is the first point of contact for air pollution in the lung, functioning as a mechanical and immunologic barrier. Under normal circumstances, airway epithelial cells connected by tight junctions secrete mucus, airway surface lining fluid, host defense peptides, and antioxidants and express innate immune pattern recognition receptors to respond to inhaled foreign substances and pathogens. Under conditions of air pollution exposure, the defenses of the airway epithelium are compromised by reductions in barrier function, impaired host defense to pathogens, and exaggerated inflammatory responses. Central to the mechanical and immunologic changes induced by air pollution are activation of redox-sensitive pathways and a role for antioxidants in normalizing these negative effects. Genetic variants in genes important in epithelial cell function and phenotype contribute to a diversity of responses to air pollution in the population at the individual and group levels and suggest a need for personalized approaches to attenuate the respiratory mucosal immune responses to air pollution.

TAK1 knock-down in macrophage alleviate lung inflammation induced by black carbon and aged black carbon

Black carbon (BC) can combine with organic matter and form secondary pollutants known as aged BC. BC and aged BC can cause respiratory system inflammation and induce lesions at relevant sites, but the underlying mechanism has remained unknown. To gain insight into the potential mechanisms, we focused on macrophages and transforming growth factor β-activated kinase 1 (TAK1) which are a crucial factor in inflammation. Our research aims to determine the role of TAK1 in macrophages in pulmonary inflammation induced by particulate matter. In this study, BC and 1,4-naphthoquinone were mixed to model aged BC (1,4NQ-BC) in atmosphere. BC induced mice lung inflammation model, lung macrophage knock-down TAK1 animal model and primary macrophage knock-down TAK1 model were used to explore whether TAK1 in macrophage is a critical role in the process of inflammation. The results showed that the expressions of inflammatory cytokines (IL-1β, IL-6, IL-33) mRNA were significantly increased and the phosphorylation of MAPK and NF-κB signaling pathway related proteins were enhanced in RAW 264.7 cell lines. In vivo studies revealed that the indicators of pulmonary inflammation (pathology, inflammatory cell numbers) and related cytokines (IL-1β, IL-6, IL-33) mRNA expressions in CD11c-Map3k7^-/- animals were significantly lower than wild-type animals after mice were instilled particles. In mice primary macrophages, the expressions of IL-6, IL-33 mRNA were inhibited after TAK1 gene was knock-down. These results unequivocally demonstrated that TAK1 plays a crucial role in BC induced lung inflammation in mice, and we can infer that BC and 1,4NQ-BC cause these inflammatory responses by stimulating pulmonary macrophages.

Skin inflammation induced by ambient particulate matter in China

Most published studies on particulate matter (PM) concerning PM_2.5 and PM₁₀ have focused on PM-induced effects on the respiratory system (particularly lung) and cardiovascular system effects. However, epidemiological and mechanistic studies suggest that PM_2.5 and PM₁₀ also affects the skin, which is a key health issue. In this study, we first reviewed the current status of PM_2.5 and PM₁₀ in China, including relevant regulations, concentration levels, chemical components, and emission sources. Next, we summarized the association between PM_2.5 and PM₁₀ or its representative components, in relation to skin inflammation as well as inflammatory skin diseases, such as atopic dermatitis, acne, eczema, and skin aging. Finally, we determined the mechanism of oxidative stress or programmed cell death induced through PM, which can provide useful information for future research on PM-induced skin inflammation.

Exploring the membrane toxicity of decabromodiphenyl ethane (DBDPE): Based on cell membranes and lipid membranes model

Decabromodiphenyl ethane (DBDPE) is widely used in industry as an alternative to the decabromodiphenyl ether (BDEs). The large-scale use of DBDPE could lead to rapid growth of the human accumulation level of DBDPE. However, the biophysics of accumulation of DBDPE in cell membranes, as one of determinants of DBDPE metabolism is not clear. In the present study, detailed observations of cell lactate dehydrogenase (LDH) and reactive oxygen species (ROS) levels measurements proved that the DBDPE exposure to cell could result in significant cell membrane damage by concentration-dependent manners. The fluorescence anisotropy analysis supported the evidence that high concentration DBDPE bound decreased membrane fluidity significantly. Besides it, a detailed molecular dynamic (MD) simulation was approached to investigate the effects of DBDPE on the DPPC (dipalmitoyl phosphatidylcholine) phospholipid bilayer, which was constructed as the model of cell membrane. The molecular dynamic simulation revealed that DBDPE molecules can easily enter the membrane from the aqueous phase. Under the concentration of a threshold, the DBDPE molecules tended to aggregate inside the DPPC bilayer and caused pore formation. The bound of high concentration of DBDPE could result in significant variations in DPPC bilayer with a less dense, more disorder and rougher layer. The knowledge about DBDPEs interactions with lipid membranes is fundamentally essential to understand the in vivo process of DBDPE and the physical basis for the toxicity of DBDPE in cell membranes.

Liquid extraction surface analysis nanospray electrospray ionization based lipidomics for in situ analysis of tumor cells with multidrug resistance

RATIONALE

Multidrug resistance (MDR) occurs frequently and is a major challenge in tumor treatment. The lipid composition in the cell membrane and the redox balance are closely associated with the development of MDR. Liquid extraction surface analysis in combination with mass spectrometry (LESA-MS) has the characteristics of minimal sample preparation, rapid analysis, high sensitivity and high throughput, and has obtained wide applications.

METHODS

LESA-MS was employed to in situ determine the lipids and other specific metabolites of intact MCF-7/ADR cells (adriamycin-resistant breast cancer cells) and its parental MCF-7/S cells grown on a glass slide. In situ atomic force microscopy was used to observe the morphology of tumor cells before and after extraction. Multivariate statistical analysis was used to investigate the potential lipid biomarkers correlated with the MDR. Moreover, the cell membrane fluidity and potential were determined.

RESULTS

The changes in the level of the lipids were closely correlated with the multidrug resistance of MCF-7/S cells. Moreover, lower cell membrane fluidity and higher cell membrane potential were observed and thus demonstrated the changes in the cell membrane induced by multidrug resistance. Also, the ratios of GSH/GSSG, ATP/ADP and ATP/AMP were significantly higher in MCF-7/ADR cells relative to MCF-7/S cells.

CONCLUSIONS

Lower cell membrane fluidity and higher cell membrane potential caused by the changes in lipid compositions, enhanced anti-oxidative ability and energy generation were involved in the development of the MDR. The specific alterations identified in this study may provide more information for overcoming MDR.

Variation in doses and duration of particulate matter exposure in bronchial epithelial cells results in upregulation of different genes associated with airway disorders

Exposure to particulate matter < 2.5 μm (PM2.5) is associated with a variety of airway diseases. Although studies have demonstrated that high doses of PM2.5 cause cytotoxicity and changes to gene expression in bronchial epithelial cells, the effect of lower doses and repeated exposure to PM2.5 are less well studied. Here, we treated BEAS-2B cells with varying doses of PM2.5 for 1-7 days and examined the expression of a variety of genes implicated in airway disorders. At high doses, PM2.5 increased the expression of IL6, TNF, TSLP, CSF2, PTGS2, IL4R, and SPINK5. Other genes such as ADAM33, ORMDL3, DPP10 and CYP1A1, however, were increased by PM2.5 at much lower doses (≤1 μg/cm2). Repeated exposure to PM2.5 at 1 or 5 μg/cm2 every day for 7 days increased the sensitivity and magnitude of change for all of the aforementioned genes. Genes such as IL13 and TGFB1, increased only when cells were repeatedly exposed to PM2.5. Treatment with an antioxidant, or inhibitors to aryl hydrocarbon receptor or NF-κB attenuated the effect of PM2.5. These data demonstrate that PM2.5 exerts pleiotropic actions that differ by dose and duration that affect a variety of genes important to the development of airway disease.