Transcriptome analysis of the cerebral cortex of acrylamide-exposed wild-type and IL-1ß-knockout mice.

Acrylamide is an environmental electrophile that has been produced in large amounts for many years. There is concern about the adverse health effects of acrylamide exposure due to its widespread industrial use and also presence in commonly consumed foods and others. IL-1ß is a key cytokine that protects the brain from inflammatory insults, but its role in acrylamide-induced neurotoxicity remains unknown. We reported recently that deletion of IL-1ß gene exacerbates ACR-induced neurotoxicity in mice. The aim of this study was to identify genes or signaling pathway(s) involved in enhancement of ACR-induced neurotoxicity by IL-1ß gene deletion or ACR-induced neurotoxicity to generate a hypothesis mechanism explaining ACR-induced neurotoxicity. C57BL/6 J wild-type and IL-1ß KO mice were exposed to ACR at 0, 12.5, 25 mg/kg by oral gavage for 7 days/week for 4 weeks, followed by extraction of mRNA from mice cerebral cortex for RNA sequence analysis. IL-1ß deletion altered the expression of genes involved in extracellular region, including upregulation of PFN1 gene related to amyotrophic lateral sclerosis and increased the expression of the opposite strand of IL-1ß. Acrylamide exposure enhanced mitochondria oxidative phosphorylation, synapse and ribosome pathways, and activated various pathways of different neurodegenerative diseases, such as Alzheimer disease, Parkinson disease, Huntington disease, and prion disease. Protein network analysis suggested the involvement of different proteins in related to learning and cognitive function, such as Egr1, Egr2, Fos, Nr4a1, and Btg2. Our results identified possible pathways involved in IL-1ß deletion-potentiated and ACR-induced neurotoxicity in mice.

Exposure to Benzo[a]pyrene Decreases Noradrenergic and Serotonergic Axons in Hippocampus of Mouse Brain.

Epidemiological studies showed the association between air pollution and dementia. A soluble fraction of particulate matters including polycyclic aromatic hydrocarbons (PAHs) is suspected to be involved with the adverse effects of air pollution on the central nervous system of humans. It is also reported that exposure to benzopyrene (B[a]P), which is one of the PAHs, caused deterioration of neurobehavioral performance in workers. The present study investigated the effect of B[a]P on noradrenergic and serotonergic axons in mouse brains. In total, 48 wild-type male mice (10 weeks of age) were allocated into 4 groups and exposed to B[a]P at 0, 2.88, 8.67 or 26.00 µg/mice, which is approximately equivalent to 0.12, 0.37 and 1.12 mg/kg bw, respectively, by pharyngeal aspiration once/week for 4 weeks. The density of noradrenergic and serotonergic axons was evaluated by immunohistochemistry in the hippocampal CA1 and CA3 areas. Exposure to B[a]P at 2.88 µg/mice or more decreased the density of noradrenergic or serotonergic axons in the CA1 area and the density of noradrenergic axons in the CA3 area in the hippocampus of mice. Furthermore, exposure to B[a]P dose-dependently upregulated Tnfα at 8.67 µg/mice or more, as well as upregulating Il-1ß at 26 µg/mice, Il-18 at 2.88 and 26 µg/mice and Nlrp3 at 2.88 µg/mice. The results demonstrate that exposure to B[a]P induces degeneration of noradrenergic or serotonergic axons and suggest the involvement of proinflammatory or inflammation-related genes with B[a]P-induced neurodegeneration.

Factory site analysis of respirable fibers generated during the process of cutting and grinding of carbon fibers-reinforced plastics.

OBJECTIVES: Carbon fibers are used in a variety of industrial applications, based on their lightweight and high stiffness properties. There is little information on the characteristics and exposure levels of debris generated during the factory processing of carbon fibers or their composites. This study revisits the general assumption that carbon fibers or their debris released during composite processing are considered safe for human health. METHODS: The present interventional study was conducted at a factory located in Japan, and involved on-site collection of debris generated during the industrial processing of polyacrylonitrile (PAN)-based carbon-fiber-reinforced plastic (CFRP). The debris were collected before being exhausted locally from around different factory machines and examined morphologically and quantitatively by scanning electron microscopy. The levels of exposure to respirable carbon fibers at different areas of the factory were also quantified. RESULTS: The collected debris mainly contained the original carbon fibers broken transversely at the fiber's major axis. However, carbon fiber fragments morphologically compatible with the WHO definition of respirable fibers (length: > 5 µm, width: < 3 µm, length/width ratio: > 3:1) were also found. The concentrations of respirable fibers at the six examined factory areas under standard working conditions in the same factory were below the standard limit of 10 fibers/L, specified for asbestos dust-generating facilities under the Air Pollution Control Law in Japan. CONCLUSIONS: Our study identified potentially dangerous respirable fibers with high aspect ratio, which was generated during the processing of PAN-based CFRP. Regular risk assessment of carbon fiber debris is necessary to ensure work environment safety.

Functionalized Surface-Charged SiO2 Nanoparticles Induce Pro-Inflammatory Responses, but Are Not Lethal to Caco-2 Cells.

Nanoparticles (NPs) are widely used in food, and analysis of their potential gastrointestinal toxicity is necessary. The present study was designed to determine the effects of silica dioxide (SiO2), titanium dioxide (TiO2), and zinc oxide (ZnO) NPs on cultured THP-1 monocyte-derived macrophages and human epithelial colorectal adenocarcinoma (Caco-2) cells. Exposure to ZnO NPs for 24 h increased the production of redox response species (ROS) and reduced cell viability in a dose-dependent manner in THP-1 macrophages and Caco-2 cells. Although TiO2 and SiO2 NPs induced oxidative stress, they showed no apparent cytotoxicity against both cell types. The effects of functionalized SiO2 NPs on undifferentiated and differentiated Caco-2 cells were investigated using fluorescently labeled SiO2 NPs with neutral, positive, or negative surface charge. Exposure of both types of cells to the three kinds of SiO2 NPs significantly increased their interaction in a dose-dependent manner. The largest interaction with both types of cells was noted with exposure to more negatively surface-charged SiO2 NPs. Exposure to either positively or negatively, but not neutrally, surface-charged SiO2 NPs increased NO levels in differentiated Caco-2 cells. Exposure of differentiated Caco-2 cells to positively or negatively surface-charged SiO2 NPs also upregulated interleukin-8 expression. We conclude that functionalized surface-charged SiO2 NPs can induce pro-inflammatory responses but are noncytotoxic.

Proteomic analysis of liver proteins of mice exposed to 1,2-dichloropropane.

1,2-Dichloropropane (1,2-DCP) is recognized as the causative agent for cholangiocarcinoma among offset color proof-printing workers in Japan. The aim of the present study was to characterize the molecular mechanisms of 1,2-DCP-induced hepatotoxic effects by proteomic analysis. We analyzed quantitatively the differential expression of proteins in the mouse liver and investigated the role of P450 in mediating the effects of 1,2-DCP. Male C57BL/6JJcl mice were exposed to 0, 50, 250, or 1250 ppm 1,2-DCP and treated with either 1-aminobenzotriazole (1-ABT), a nonselective P450 inhibitor, or saline, for 8 h/day for 4 weeks. Two-dimensional difference in gel electrophoresis (2D-DIGE) combined with matrix-assisted laser-desorption ionization time-of-flight mass spectrometry (MALDI-TOF/TOF/MS) was used to detect and identify proteins affected by the treatment. PANTHER overrepresentation test on the identified proteins was conducted. 2D-DIGE detected 61 spots with significantly different intensity between 0 and 250 ppm 1,2-DCP groups. Among them, 25 spots were identified by MALDI-TOF/TOF/MS. Linear regression analysis showed significant trend with 1,2-DCP level in 17 proteins in mice co-treated with 1-ABT. 1-ABT mitigated the differential expression of these proteins. The gene ontology enrichment analysis showed overrepresentation of proteins functionally related to nickel cation binding, carboxylic ester hydrolase activity, and catalytic activity. The results demonstrated that exposure to 1,2-DCP altered the expression of proteins related with catalytic and carboxylic ester hydrolase activities, and that such effect was mediated by P450 enzymatic activity.

Genome-wide association study revealed novel loci which aggravate asymptomatic hyperuricaemia into gout.

OBJECTIVE: The first ever genome-wide association study (GWAS) of clinically defined gout cases and asymptomatic hyperuricaemia (AHUA) controls was performed to identify novel gout loci that aggravate AHUA into gout. METHODS: We carried out a GWAS of 945 clinically defined gout cases and 1003 AHUA controls followed by 2 replication studies. In total, 2860 gout cases and 3149 AHUA controls (all Japanese men) were analysed. We also compared the ORs for each locus in the present GWAS (gout vs AHUA) with those in the previous GWAS (gout vs normouricaemia). RESULTS: This new approach enabled us to identify two novel gout loci (rs7927466 of CNTN5 and rs9952962 of MIR302F) and one suggestive locus (rs12980365 of ZNF724) at the genome-wide significance level (p<5.0×10-8). The present study also identified the loci of ABCG2, ALDH2 and SLC2A9. One of them, rs671 of ALDH2, was identified as a gout locus by GWAS for the first time. Comparing ORs for each locus in the present versus the previous GWAS revealed three 'gout vs AHUA GWAS'-specific loci (CNTN5, MIR302F and ZNF724) to be clearly associated with mechanisms of gout development which distinctly differ from the known gout risk loci that basically elevate serum uric acid level. CONCLUSIONS: This meta-analysis is the first to reveal the loci associated with crystal-induced inflammation, the last step in gout development that aggravates AHUA into gout. Our findings should help to elucidate the molecular mechanisms of gout development and assist the prevention of gout attacks in high-risk AHUA individuals.

Role of Nrf2 in inflammatory response in lung of mice exposed to zinc oxide nanoparticles.

BACKGROUND: Zinc oxide nanoparticles (ZnO-NPs) are widely used in many industrial sectors and previous studies have reported that exposure of the lungs to ZnO-NPs induces both acute and/or chronic pulmonary inflammation, but the exact mechanism underlying such response remains elusive. This study investigated the role of nuclear factor-erythroid 2-related factor (Nrf2) in pulmonary inflammation induced by exposure to ZnO-NPs using Nrf2 null (Nrf2-/-) mice. METHODS: Twenty-four male Nrf2-/- mice and thirty male wild type C57BL/6 J mice were divided into three groups of eight and ten each respectively, and exposed once to ZnO-NPs at 0, 10, 30 µg/mouse by pharyngeal aspiration. At 14 days after the exposure to ZnO-NPs, bronchoalveolar lavage fluid (BALF) and lungs were collected to quantify protein level and the number of inflammatory cells. The mRNA levels of Nrf2-dependent antioxidant enzymes and inflammatory cytokines in lung tissue were measured. RESULTS: Exposure to ZnO-NPs dose-dependently increased the number of total cells, macrophages, lymphocytes and eosinophils in BALF both in Nrf2-/- mice and wild type mice, but the magnitude of increase was significantly higher in Nrf2-/- mice than wild type mice. The number of neutrophils in BALF increased in Nrf2-/- mice, being accompanied by marginal trend of increase in mRNA expression of MIP-2, neutrophil chemoattractant, but such changes were not observed in wild type mice. Exposure to ZnO-NPs did not dose-dependently increase mRNA level of Nrf2-dependent antioxidant enzymes both in Nrf2-/- mice and wild type mice. CONCLUSION: Pharyngeal aspiration of ZnO-NPs induced infiltration of inflammatory cells in the lung of mice, but minimally induced Nrf2-dependent antioxidant enzymes. The results suggest that Nrf2 play a role in negative regulation on ZnO-NP exposure-induced neutrophil migration, but does not demonstrate that the regulation is through suppression of oxidative stress.

Correction to: Particle toxicology and health - where are we?

After the publication of this article [1] it was hihglighted that the number of deaths related to natural disasters was incorrectly reported in the second paragraph of the Hazards from Natural particulates and the evolution of the biosphere section. This correction article shows the correct and incorrect statement. This correction does not change the idea presented in the article that from an evolutionary view point, natural disasters account only for a small fraction of the people on the planet. The original article has been updated.

Particle toxicology and health - where are we?

BACKGROUND: Particles and fibres affect human health as a function of their properties such as chemical composition, size and shape but also depending on complex interactions in an organism that occur at various levels between particle uptake and target organ responses. While particulate pollution is one of the leading contributors to the global burden of disease, particles are also increasingly used for medical purposes. Over the past decades we have gained considerable experience in how particle properties and particle-bio interactions are linked to human health. This insight is useful for improved risk management in the case of unwanted health effects but also for developing novel medical therapies. The concepts that help us better understand particles' and fibres' risks include the fate of particles in the body; exposure, dosimetry and dose-metrics and the 5 Bs: bioavailability, biopersistence, bioprocessing, biomodification and bioclearance of (nano)particles. This includes the role of the biomolecule corona, immunity and systemic responses, non-specific effects in the lungs and other body parts, particle effects and the developing body, and the link from the natural environment to human health. The importance of these different concepts for the human health risk depends not only on the properties of the particles and fibres, but is also strongly influenced by production, use and disposal scenarios. CONCLUSIONS: Lessons learned from the past can prove helpful for the future of the field, notably for understanding novel particles and fibres and for defining appropriate risk management and governance approaches.

Proteomic analysis of hippocampal proteins in acrylamide-exposed Wistar rats.

Acrylamide has been used industrially and also found in certain foods cooked at high temperatures. Previous reports described acrylamide-related human intoxication who presented with ataxia, memory impairment, and/or illusion. The aim of this study was to characterize the molecular mechanisms of neurotoxicity of acrylamide by analyzing the expression levels of various proteins in the hippocampus of rats exposed to acrylamide. Male Wistar rats were administered acrylamide by gavage at 0, 2, and 20 mg/kg for 1 week or 0, 0.2, 2, and 20 mg/kg for 5 weeks. At the end of the experiment, the hippocampus was dissected out and proteins were extracted for two-dimensional difference gel electrophoresis combined with matrix-assisted laser-desorption ionization time-of-flight/time-of-flight mass spectrometry (MALDI-TOF/TOF/MS). MALDI-TOF/TOF/MS identified significant changes in two proteins in the 1-week and 22 proteins in the 5-week exposure groups. These changes were up-regulation in 9 and down-regulation in 13 proteins in the hippocampus of rats exposed to acrylamide at 20 mg/kg for 5 weeks. PANTHER overrepresentation test based on the GO of biological process showed significant overrepresentation in proteins annotated to nicotinamide nucleotide metabolic process, coenzyme biosynthetic process, pyruvate metabolic process, and carbohydrate metabolic process. The test also showed significant overrepresentation in proteins annotated to creatinine kinase activity for the GO of molecular function as well as myelin sheath, cytoplasmic part, and cell body for the GO of cellular component. Comparison with a previous proteomic study on hippocampal proteins in rats exposed to 1-bromopropane identified triosephosphate isomerase, mitochondrial creatine kinase U-type, creatine kinase ß-type and proteasome subunit α type-1 as proteins affected by exposure to acrylamide and 1-bromopropane, suggesting a common mechanism of neurotoxicity for soft electrophiles.

Role of microglial activation and neuroinflammation in neurotoxicity of acrylamide in vivo and in vitro.

Acrylamide, a soft electrophile, is widely used in the industry and laboratories, and also contaminates certain foods. Neurotoxicity and neurodegenerative effects of acrylamide have been reported in humans and experimental animals, although the underlying mechanism remains obscure. Activation of microglia and neuroinflammation has been demonstrated in various neurodegenerative diseases as well as other pathologies of the brain. The present study aimed to investigate the role of microglial activation and neuroinflammation in acrylamide neurotoxicity. Male 10-week-old Wistar rats were exposed to acrylamide by gavage at 0, 0.2, 2, or 20 mg/kg BW, once per day for 5 weeks. The results showed that 5-week exposure to acrylamide induced inflammatory responses in the cerebral cortex, evident by upregulated mRNA and protein expression of pro-inflammatory cytokines IL-1ß, IL-6, and IL-18. Acrylamide also induced activation of microglia, indicated by increased expression of microglial markers, CD11b and CD40, and increased CD11b/c-positive microglial area and microglial process length. In vitro studies using BV-2 microglial cells confirmed microglial inflammatory response, as evident by time- (0-36 h; 50 µM) and dose- (0-500 µM; 24 h) dependent increase in mRNA expression of IL-1ß and IL-18, as well as the inflammatory marker iNOS. Furthermore, acrylamide-induced upregulation of pro-inflammatory cytokines was mediated through the NLRP3 inflammasome pathway, as evident by increased expression of NLRP3, caspase 1, and ASC in the rat cerebral cortex, and by the inhibitory effects of NLRP3 inflammasome inhibitor on the acrylamide-induced upregulation of NLRP3, caspase 1, IL-1ß, and IL-18 in BV-2 microglia.

Ablation of aryl hydrocarbon receptor promotes angiotensin II-induced cardiac fibrosis through enhanced c-Jun/HIF-1α signaling.

Aryl hydrocarbon receptor (AHR) is a transcription factor that binds to DNA as a heterodimer with the AHR nuclear translocator (ARNT) after interaction with ligands, such as polycyclic and halogenated aromatic hydrocarbons and other xenobiotics. The endogenous ligands and functions of AHR have been the subject of many investigations. In the present study, the potential role of AHR signaling in the development of left ventricular hypertrophy and cardiac fibrosis by angiotensin II (Ang II) infusion was investigated in mice lacking the AHR gene (Ahr-/-). We also assessed the hypothesis that fenofibrate, a peroxisome proliferator-activated receptor-α (PPARα) activator, reduces cardiac fibrosis through the c-Jun signaling. Male Ahr-/- and age-matched wild-type mice (n = 8 per group) were infused with Ang II at 100 ng/kg/min daily for 2 weeks. Treatment with Ang II increased systolic blood pressure to comparable levels in Ahr-/- and wild-type mice. However, Ahr-/- mice developed severe cardiac fibrosis after Ang II infusion compared with wild-type mice. Ang II infusion also significantly increased the expression of endothelin in the left ventricles of Ahr-/- mice, but not in wild-type mice, and significantly increased the c-Jun signaling in Ahr-/- mice. Ang II infusion also significantly enhanced the expression of hypoxia-inducible factor-1α (HIF-1α) and the downstream target vascular endothelial growth factor (VEGF) in the left ventricles of Ahr-/- mice. These results suggested pathogenic roles for the AHR signaling pathway in the development of cardiac fibrosis. Treatment with fenofibrate reduced cardiac fibrosis and abrogated the effects of Ang II on the expression of endothelin, HIF-1α, and VEGF. The inhibitory effect of fenofibrate on cardiac fibrosis was mediated by suppression of VEGF expression through modulation of c-Jun/HIF-1α signaling.

Toxicological Evaluation of SiO2 Nanoparticles by Zebrafish Embryo Toxicity Test.

As the use of nanoparticles (NPs) is increasing, the potential toxicity and behavior of NPs in living systems need to be better understood. Our goal was to evaluate the developmental toxicity and bio-distribution of two different sizes of fluorescently-labeled SiO2 NPs, 25 and 115 nm, with neutral surface charge or with different surface functionalization, rendering them positively or negatively charged, in order to predict the effect of NPs in humans. We performed a zebrafish embryo toxicity test (ZFET) by exposing the embryos to SiO2 NPs starting from six hours post fertilization (hpf). Survival rate, hatching time, and gross morphological changes were assessed at 12, 24, 36, 48, 60, and 72 hpf. We evaluated the effect of NPs on angiogenesis by counting the number of sub-intestinal vessels between the second and seventh intersegmental vessels and gene expression analysis of vascular endothelial growth factor (VEGF) and VEGF receptors at 72 hpf. SiO2 NPs did not show any adverse effects on survival rate, hatching time, gross morphology, or physiological angiogenesis. We found that SiO2 NPs were trapped by the chorion up until to the hatching stage. After chemical removal of the chorion (dechorionation), positively surface-charged SiO2 NPs (25 nm) significantly reduced the survival rate of the fish compared to the control group. These results indicate that zebrafish chorion acts as a physical barrier against SiO2 NPs, and removing the chorions in ZFET might be necessary for evaluation of toxicity of NPs.

MicroRNAs as Potential Mediators for Cigarette Smoking Induced Atherosclerosis.

Smoking increases the risk of atherosclerosis-related events, such as myocardial infarction and ischemic stroke. Recent studies have examined the expression levels of altered microRNAs (miRNAs) in various diseases. The profiles of tissue miRNAs can be potentially used in diagnosis or prognosis. However, there are limited studies on miRNAs following exposure to cigarette smoke (CS). The present study was designed to dissect the effects and cellular/molecular mechanisms of CS-induced atherosclerogenesis. Apolipoprotein E knockout (ApoE KO) mice were exposed to CS for five days a week for two months at low (two puffs/min for 40 min/day) or high dose (two puffs/min for 120 min/day). We measured the area of atherosclerotic plaques in the aorta, representing the expression of miRNAs after the exposure period. Two-month exposure to the high dose of CS significantly increased the plaque area in aortic arch, and significantly upregulated the expression of atherosclerotic markers (VCAM-1, ICAM-1, MCP1, p22phox, and gp91phox). Exposure to the high dose of CS also significantly upregulated the miRNA-155 level in the aortic tissues of ApoE KO mice. Moreover, the expression level of miR-126 tended to be downregulated and that of miR-21 tended to be upregulated in ApoE KO mice exposed to the high dose of CS, albeit statistically insignificant. The results suggest that CS induces atherosclerosis through increased vascular inflammation and NADPH oxidase expression and also emphasize the importance of miRNAs in the pathogenesis of CS-induced atherosclerosis. Our findings provide evidence for miRNAs as potential mediators of inflammation and atherosclerosis induced by CS.

Effect of 4-week inhalation exposure to 1-bromopropane on blood pressure in rats.

The pathophysiology of hypertension is complex and multifactorial, and includes exposure to various chemical substances. Several recent studies have documented the reproductive and neurological toxicities of 1-bromopropane (1-BP). Given that 1-BP increased reactive oxygen species in the brain of rats, we hypothesized that 1-BP also has cardiovascular toxicity through increased oxidative stress. To test this hypothesis, male F344 and Wistar Nagoya rats (n = 7-8 per group per test) were exposed to 0 or 1000 ppm of 1-BP via inhalation for 4 weeks (8 h per day, 7 days per week). The exposure to 1-BP increased systolic blood pressure. This effect was associated with a significant decrease in the reduced/oxidized glutathione ratio. A significant increase in nitrotyrosine levels, activation of the NADPH oxidase pathway, which was evidenced by upregulation of gp91phox, a NADPH oxidase subunit, and significant decreases in the expressions of antioxidant molecules such as Cu/Zn- and Mn-superoxide dismutase catalase, and nuclear factor erythroid 2-related factor 2, were observed in the aortas of Wistar Nagoya rats exposed to 1-BP. Our results indicate that subacute (4-week) inhalation exposure to 1-BP increases blood pressure and suggest that this cardiovascular toxic effect is due, at least in part, to increased oxidative stress mediated through activation of the NADPH oxidase pathway. Further study is needed to assess whether NADPH oxidase activation causes the increase in blood pressure in the rats exposed to 1-BP. Copyright © 2016 John Wiley & Sons, Ltd.

A meta-analysis of genome-wide association studies for adiponectin levels in East Asians identifies a novel locus near WDR11-FGFR2.

Blood levels of adiponectin, an adipocyte-secreted protein correlated with metabolic and cardiovascular risks, are highly heritable. Genome-wide association (GWA) studies for adiponectin levels have identified 14 loci harboring variants associated with blood levels of adiponectin. To identify novel adiponectin-associated loci, particularly those of importance in East Asians, we conducted a meta-analysis of GWA studies for adiponectin in 7827 individuals, followed by two stages of replications in 4298 and 5954 additional individuals. We identified a novel adiponectin-associated locus on chromosome 10 near WDR11-FGFR2 (P = 3.0 × 10(-14)) and provided suggestive evidence for a locus on chromosome 12 near OR8S1-LALBA (P = 1.2 × 10(-7)). Of the adiponectin-associated loci previously described, we confirmed the association at CDH13 (P = 6.8 × 10(-165)), ADIPOQ (P = 1.8 × 10(-22)), PEPD (P = 3.6 × 10(-12)), CMIP (P = 2.1 × 10(-10)), ZNF664 (P = 2.3 × 10(-7)) and GPR109A (P = 7.4 × 10(-6)). Conditional analysis at ADIPOQ revealed a second signal with suggestive evidence of association only after conditioning on the lead SNP (Pinitial = 0.020; Pconditional = 7.0 × 10(-7)). We further confirmed the independence of two pairs of closely located loci (<2 Mb) on chromosome 16 at CMIP and CDH13, and on chromosome 12 at GPR109A and ZNF664. In addition, the newly identified signal near WDR11-FGFR2 exhibited evidence of association with triglycerides (P = 3.3 × 10(-4)), high density lipoprotein cholesterol (HDL-C, P = 4.9 × 10(-4)) and body mass index (BMI)-adjusted waist-hip ratio (P = 9.8 × 10(-3)). These findings improve our knowledge of the genetic basis of adiponectin variation, demonstrate the shared allelic architecture for adiponectin with lipids and central obesity and motivate further studies of underlying mechanisms.

Single- and double-walled carbon nanotubes enhance atherosclerogenesis by promoting monocyte adhesion to endothelial cells and endothelial progenitor cell dysfunction.

BACKGROUND: The use of carbon nanotubes has increased lately. However, the cardiovascular effect of exposure to carbon nanotubes remains elusive. The present study investigated the effects of pulmonary exposure to single-walled carbon nanotubes (SWCNTs) and double-walled carbon nanotubes (DWCNTs) on atherosclerogenesis using normal human aortic endothelial cells (HAECs) and apolipoprotein E-deficient (ApoE-/-) mice, a model of human atherosclerosis. METHODS: HAECs were cultured and exposed to SWCNTs or DWCNTs for 16 h. ApoE-/- mice were exposed to SWCNTs or DWCNTs (10 or 40 µg/mouse) once every other week for 10 weeks by pharyngeal aspiration. RESULTS: Exposure to CNTs increased the expression level of adhesion molecule (ICAM-1) and enhanced THP-1 monocyte adhesion to HAECs. ApoE-/- mice exposed to CNTs showed increased plaque area in the aorta by oil red O staining and up-regulation of ICAM-1 expression in the aorta, compared with vehicle-treated ApoE-/- mice. Endothelial progenitor cells (EPCs) are mobilized from the bone marrow into the circulation and subsequently migrate to the site of endothelial damage and repair. Exposure of ApoE-/- mice to high-dose SWCNTs or DWCNTs reduced the colony-forming units of EPCs in the bone marrow and diminished their migration function. CONCLUSION: The results suggested that SWCNTs and DWCNTs enhanced atherosclerogenesis by promoting monocyte adhesion to endothelial cells and inducing EPC dysfunction.

Titanium Dioxide Particle Type and Concentration Influence the Inflammatory Response in Caco-2 Cells.

Titanium dioxide (TiO2) nanoparticles are widely used in cosmetics, sunscreens, biomedicine, and food products. When used as a food additive, TiO2 nanoparticles are used in significant amounts as white food-coloring agents. However, the effects of TiO2 nanoparticles on the gastrointestinal tract remain unclear. The present study was designed to determine the effects of five TiO2 particles of different crystal structures and sizes in human epithelial colorectal adenocarcinoma (Caco-2) cells and THP-1 monocyte-derived macrophages. Twenty-four-hour exposure to anatase (primary particle size: 50 and 100 nm) and rutile (50 nm) TiO2 particles reduced cellular viability in a dose-dependent manner in THP-1 macrophages, but in not Caco-2 cells. However, 72-h exposure of Caco-2 cells to anatase (50 nm) TiO2 particles reduced cellular viability in a dose-dependent manner. The highest dose (50 µg/mL) of anatase (100 nm), rutile (50 nm), and P25 TiO2 particles also reduced cellular viability in Caco-2 cells. The production of reactive oxygen species tended to increase in both types of cells, irrespective of the type of TiO2 particle. Exposure of THP-1 macrophages to 50 µg/mL of anatase (50 nm) TiO2 particles increased interleukin (IL)-1ß expression level, and exposure of Caco-2 cells to 50 µg/mL of anatase (50 nm) TiO2 particles also increased IL-8 expression. The results indicated that anatase TiO2 nanoparticles induced inflammatory responses compared with other TiO2 particles. Further studies are required to determine the in vivo relevance of these findings to avoid the hazards of ingested particles.

Epigenome-wide association study suggests that SNPs in the promoter region of RETN influence plasma resistin level via effects on DNA methylation at neighbouring sites.

AIMS/HYPOTHESIS: To investigate epigenetic regulation of the plasma concentration of resistin, we performed an epigenome-wide association study for this variable and DNA methylation (DNAm) in an elderly Japanese cohort and then assessed the relation of single nucleotide polymorphisms (SNPs) associated with the plasma resistin concentration to DNAm level at identified sites. METHODS: The association of plasma resistin level with DNAm status was examined in 191 nondiabetic elderly men with the Illumina Infinium HumanMethylation450 BeadChip array. The association between DNAm status at specific sites in the flanking region of the resistin gene (RETN) and RETN mRNA abundance was then evaluated with a public data set for 1202 monocyte samples from a multi-ethnic cohort. Finally, the association of DNAm status and SNPs in the promoter region of RETN was assessed in two cohorts comprising a total of 478 Japanese individuals. RESULTS: DNAm status at cg02346997 located in the RETN promoter region showed a negative genome-wide significant association with the plasma resistin level (p = 6.02 × 10(-10)). Four DNAm sites in the RETN promoter region including cg02346997 (p = 4.23 × 10(-70)) showed a negative genome-wide significant association with RETN mRNA abundance in monocytes. Furthermore, the number of minor alleles of the RETN promoter SNPs rs34861192 and rs3219175 was negatively associated with DNAm level at cg02346997 (p = 4.43 × 10(-17)). CONCLUSIONS/INTERPRETATION: Our results suggest that RETN promoter SNPs might influence the circulating resistin level through an effect on DNAm at cg02346997 and on RETN mRNA abundance in monocytes.