Diesel exhaust particulates affect cell signaling,mucin profiles,and apoptosis in trachea explants of Balb/C mice

Particulate matter from diesel exhaust (DEP) has toxic properties and can activate intracellular signaling pathways and induce metabolic changes. This study was conducted to evaluate the activation of extracellular signal‐regulated kinase (ERK) and c‐Jun N‐terminal kinase (JNK) and to analyze the mucin profile (acid (AB⁺), neutral (PAS⁺), or mixed (AB/PAS⁺) mucus) and vacuolization (V) of tracheal explants after treatment with 50 or 100 μg/mL DEP for 30 or 60 min. Western blot analyses showed small increases in ERK1/2 and JNK phosphorylation after 30 min of 100 μg/mL DEP treatment compared with the control. An increase in JNK phosphorylation was observed after 60 min of treatment with 50 μg/mL DEP compared with the control. We did not observe any change in the level of ERK1/2 phosphorylation after treatment with 50 μg/mL DEP. Other groups of tracheas were subjected to histological sectioning and stained with periodic acid‐Schiff (PAS) reagent and Alcian Blue (AB). The stained tissue sections were then subjected to morphometric analysis. The results obtained were compared using ANOVA. Treatment with 50 μg/mL DEP for 30 min or 60 min showed a significant increase (p < 0.001) in the amount of acid mucus, a reduction in neutral mucus, a significant reduction in mixed mucus, and greater vacuolization. Our results suggest that compounds found in DEPs are able to activate acid mucus production and enhance vacuolization and cell signaling pathways, which can lead to airway diseases. © 2014 Wiley Periodicals, Inc. Environ Toxicol 30: 1297–1308, 2015.     

Lower Extremity Revascularization Using Directional Atherectomy: 12-Month Prospective Results of the DEFINITIVE LE Study

ObjectivesThe aim of this study was to assess the safety and effectiveness of directional atherectomy (DA) for endovascular treatment of peripheral arterial disease (PAD) in infrainguinal arteries in patients with claudication or critical limb ischemia.BackgroundTo date, no prospective, multicenter, independently-adjudicated study has evaluated the effectiveness and durability of DA in the treatment of PAD. Previous DA studies have not been prospectively powered to evaluate any differences in outcomes in patients with and without diabetes.MethodsDEFINITIVE LE (Determination of EFfectiveness of the SilverHawk® PerIpheral Plaque ExcisioN System (SIlverHawk Device) for the Treatment of Infrainguinal VEssels / Lower Extremities) prospectively enrolled subjects at 47 multinational centers with an infrainguinal lesion length up to 20 cm. Primary endpoints were defined as primary patency at 12 months for claudicants and freedom from major unplanned amputation for critical limb ischemia (CLI) subjects. A pre-specified statistical hypothesis evaluated noninferiority of primary patency in diabetic versus nondiabetic claudicants. Independent angiographic and sonographic core laboratories assessed outcomes, and events were adjudicated by a clinical events committee.ResultsA total of 800 subjects were enrolled. The 12-month primary patency was 78% (95% confidence interval: 74.0% to 80.6%) in claudicants, with a 77% rate in the diabetic subgroup versus 78% in the nondiabetic subgroup (noninferior, p < 0.001). The rate of freedom from major unplanned amputation of the target limb at 12 months in CLI subjects was 95% (95% confidence interval: 90.7% to 97.4%). Periprocedural adverse events included embolization (3.8%), perforation (5.3%), and abrupt closure (2.0%). The bail-out stent rate was 3.2%.ConclusionsThe DEFINITIVE LE study demonstrated that DA is a safe and effective treatment modality at 12 months for a diverse patient population with either claudication or CLI. Furthermore, DA was shown to be noninferior for treating PAD in patients with diabetes compared with those without diabetes. (Study of SilverHawk/TurboHawk in Lower Extremity Vessels [DEFINITIVE LE]; NCT00883246).     

Accumulation of lipids and oxidatively damaged DNA in hepatocytes exposed to particles

Exposure to particles has been suggested to generate hepatosteatosis by oxidative stress mechanisms. We investigated lipid accumulation in cultured human hepatocytes (HepG2) and rat liver after exposure to four different carbon-based particles. HepG2 cells were exposed to particles for 3 h and subsequently incubated for another 18 h to manifest lipid accumulation. In an animal model of metabolic syndrome we investigated the association between intake of carbon black (CB, 14 nm) particles and hepatic lipid accumulation, inflammation and gene expression of Srebp-1, Fasn and Scd-1 involved in lipid synthesis. There was a concentration-dependent increase in intracellular lipid content after exposure to CB in HepG2 cells, which was only observed after co-exposure to oleic/palmitic acid. Similar results were observed in HepG2 cells after exposure to diesel exhaust particles, fullerenes C₆₀ or pristine single-walled carbon nanotubes. All four types of particles also generated oxidatively damaged DNA, assessed as formamidopyrimidine DNA glycosylase (FPG) sensitive sites, in HepG2 cells after 3 h exposure. The animal model of metabolic syndrome showed increased lipid load in the liver after one oral exposure to 6.4 mg/kg of CB in lean Zucker rats. This was not associated with increased iNOS staining in the liver, indicating that the oral CB exposure was associated with hepatic steatosis rather than steatohepatitis. The lipid accumulation did not seem to be related to increased lipogenesis because there were unaltered gene expression levels in both the HepG2 cells and rat livers. Collectively, exposure to particles is associated with oxidative stress and steatosis in hepatocytes.     

Oxidative DNA damage and inflammatory responses in cultured human cells and in humans exposed to traffic-related particles

Particulate pollution is a major public health concern because epidemiological studies have demonstrated that exposure to particles is associated with respiratory diseases and lung cancer. Diesel exhaust particles (DEP), which is classified as a human carcinogen (IARC, 2012), are considered a major contributor to traffic-related particulate matter (PM) in urban areas. DEP consists of various compounds, including PAHs and metals which are the principal components that contribute to the toxicity of PM. The present study aimed to investigate effects of PM on induction of oxidative DNA damage and inflammation by using lymphocytes in vitro and in human exposed to PM in the environment. Human lymphoblasts (RPMI 1788) were treated with DEP (SRM 2975) at various concentrations (25–100 μg/ml) to compare the extent of responses with alveolar epithelial cells (A549). ROS generation was determined in each cell cycle phase of DEP-treated cells in order to investigate the influence of the cell cycle stage on induction of oxidative stress. The oxidative DNA damage was determined by measurement of 8-hydroxy-deoxyguanosine (8-OHdG) whereas the inflammatory responses were determined by mRNA expression of interleukin-6 and -8 (IL-6 and IL-8), Clara cell protein (CC16), and lung surfactant protein-A (SP-A). The results showed that RPMI 1788 and A549 cells had a similar pattern of dose-dependent responses to DEP in terms of particle uptake, ROS generation with highest level found in G2/M phase, 8-OHdG formation, and induction of IL-6 and IL-8 expression. The human study was conducted in 51 healthy subjects residing in traffic-congested areas. The effects of exposure to PM_2.5 and particle-bound PAHs and toxic metals on the levels of 8-OHdG in lymphocyte DNA, IL-8 expression in lymphocytes, and serum CC16 were evaluated. 8-OHdG levels correlated with the exposure levels of PM_2.5 (P < 0.01) and PAHs (P < 0.05), but this was not the case with IL-8. Serum CC16 showed significantly negative correlations with B[a]P equivalent (P < 0.05) levels, but positive correlation with Pb (P < 0.05). In conclusion, a similar pattern of the dose-dependent responses to DEP in the lymphoblasts and lung cells suggests that circulating lymphocytes could be used as a surrogate for assessing PM-induced oxidative DNA damage and inflammatory responses in the lung. Human exposure to PM leads to oxidative DNA damage whereas PM-induced inflammation was not conclusive and should be further investigated.     

Immunohistological study for estrogenic activities of nitrophenols in diesel exhaust particles

We recently isolated 3-methyl-4-nitrophenol (4-nitro-m-cresol; PNMC) and 4-nitro-3-phenylphenol (PNMPP) from diesel exhaust particles (DEP) and identified them as vasodilators and xenoestrogens. The estrogenic activity of PNMC and PNMPP was further examined by using immunohistochemical staining of proliferating cell nuclear antigen (PCNA) in uterine luminal epithelium of ovariectomized 25-d-old immature female rats injected with PNMC and PNMPP subcutaneously for 2 d. Significant increases were observed in uterine luminal epithelium in PCNA positive cells of animals receiving 10 and 100 mg/kg PNMC and 0.1 mg/kg PNMPP compared with controls. These results clearly show the estrogenic activity of PNMC and PNMPP by cell proliferation on the uterine luminal epithelium.     

Role of Paris PM2.5 components in the pro-inflammatory response induced in airway epithelial cells

Particulate matter (PM) is suspected to play a role in environmentally-induced pathologies. Due to its complex composition, the contribution of each PM components to PM-induced biological effects remains unclear.     

Microarray analysis of gene expression in rat alveolar epithelial cells exposed to fractionated organic extracts of diesel exhaust particles

Diesel exhaust particles (DEP) affect health adversely. Our previous studies revealed that DEP extracts up-regulated expression of genes related to drug metabolism, antioxidant enzymes, cell cycle/apoptosis and coagulation, and in addition, n-hexane soluble fraction (n-HSF) of DEP extracts contains aliphatic and polycyclic aromatic hydrocarbons, and n-hexane insoluble fraction (n-HISF) contains oxygenated compounds and has strong oxidative property. However, the relationship between the properties of chemicals in DEP extracts and the gene expression has not been fully elucidated. Here, we used a microarray analysis to identify and characterize genes whose expression is regulated by exposure to fractions of DEP extracts. A dichloromethane-soluble fraction (DMSF) of DEP was further fractionated into n-HSF and n-HISF. We exposed rat alveolar epithelial (SV40T2) cells to these fractions (30 μg/ml) for 6 h and identified regulated genes. DMSF predominantly up-regulated genes associated with drug metabolism (Cyp1a1, Gsta3), oxidative stress response (HO-1, Srxn1) and cell cycle/apoptosis (Okl38). Genes up-regulated by n-HSF were mainly associated with drug metabolism (Cyp1a1, Gsta3). The genes up-regulated by n-HISF included antioxidant enzymes (HO-1, Srxn1); genes response to cell damage, such as those functioning in cell cycle regulation or apoptosis (Okl38); and genes in coagulation pathways. Our present results suggested that n-HSF and n-HISF regulated characteristic genes which respond to chemical properties of each fraction.     

Diesel exhaust particles induce endothelial dysfunction in apoE-/- mice

BACKGROUND: Particulate air pollution can aggravate cardiovascular disease by mechanisms suggested to involve translocation of particles to the bloodstream and impairment of endothelial function, possibly dependent on present atherosclerosis. AIM: We investigated the effects of exposure to diesel exhaust particles (DEP) in vivo and ex vivo on vasomotor functions in aorta from apoE(-/-) mice with slight atherosclerosis and from normal apoE(+/+) mice. METHODS: DEP 0, 0.5 or 5 mg/kg bodyweight in saline was administered i.p. The mice were sacrificed 1 h later and aorta ring segments were mounted on wire myographs. Segments from unexposed mice were also incubated ex vivo with 0, 10 and 100 microg DEP/ml before measurement of vasomotor functions. RESULTS: Exposure to 0.5 mg/kg DEP in vivo caused a decrease in the endothelium-dependent acetylcholine elicited vasorelaxation in apoE(-/-) mice, whereas the response was enhanced in apoE(+/+) mice. No significant change was observed after administration of 5 mg/kg DEP. In vivo DEP exposure did not affect constriction induced by K(+) or phenylephrine. In vitro exposure to 100 microg DEP/ml enhanced acetylcholine-induced relaxation and attenuated phenylephrine-induced constriction. Vasodilation induced by sodium nitroprusside was not affected by any DEP exposure. CONCLUSION: Exposure to DEP has acute effect on vascular functions. Endothelial dysfunction possibly due to decreased NO production as suggested by decreased acetylcholine-induced vasorelaxation and unchanged sodium nitroprusside response can be induced by DEP in vivo only in vessels of mice with some atherosclerosis.