International regulatory uses of acute systemic toxicity data and integration of new approach methodologies.

Chemical regulatory authorities around the world require systemic toxicity data from acute exposures via the oral, dermal, and inhalation routes for human health risk assessment. To identify opportunities for regulatory uses of non-animal replacements for these tests, we reviewed acute systemic toxicity testing requirements for jurisdictions that participate in the International Cooperation on Alternative Test Methods (ICATM): Brazil, Canada, China, the European Union, Japan, South Korea, Taiwan, and the USA. The chemical sectors included in our review of each jurisdiction were cosmetics, consumer products, industrial chemicals, pharmaceuticals, medical devices, and pesticides. We found acute systemic toxicity data were most often required for hazard assessment, classification, and labeling, and to a lesser extent quantitative risk assessment. Where animal methods were required, animal reduction methods were typically recommended. For many jurisdictions and chemical sectors, non-animal alternatives are not accepted, but several jurisdictions provide guidance to support the use of test waivers to reduce animal use for specific applications. An understanding of international regulatory requirements for acute systemic toxicity testing will inform ICATM's strategy for the development, acceptance, and implementation of non-animal alternatives to assess the health hazards and risks associated with acute toxicity.

Air quality health index (AQHI) based on multiple air pollutants and mortality risks in Taiwan: Construction and validation.

The currently used air quality index (AQI) is not able to capture the additive effects of air pollution on health risks and reflect non-threshold concentration-response relationships, which has been criticized. We proposed the air quality health index (AQHI) based on daily air pollution-mortality associations, and compared its validity in predicting daily mortality and morbidity risks with the existing AQI. We examined the excess risk (ER) of daily elderly (≥65-year-old) mortality associated with 6 air pollutants (PM2.5, PM10, SO2, CO, NO2, and O3) in 72 townships across Taiwan from 2006 to 2014 by performing a time-series analysis using a Poisson regression model. Random effect meta-analysis was used to pool the township-specified ER for each air pollutant in the overall and seasonal scenarios. The integrated ERs for mortality were calculated and used to construct the AQHI. The association of the AQHI with daily mortality and morbidity were compared by calculating the percentage change per interquartile range (IQR) increase in the indices. The magnitude of the ER on the concentration-response curve was used to evaluate the performance of the AQHI and AQI, regarding specific health outcomes. Sensitivity analysis was conducted using coefficients from the single- and two-pollutant models. The coefficients of PM2.5, NO2, SO2, and O3 associated with mortality were included to form the overall and season-specific AQHI. An IQR increase in the overall AQHI at lag 0 was associated with 1.90%, 2.96%, and 2.68% increases in mortality, asthma, and respiratory outpatient visits, respectively. The AQHI had higher ERs for mortality and morbidity on the validity examinations than the current AQI. The AQHI, which captures the combined effects of air pollution, can serve as a health risk communication tool to the public.

Study Protocol for Radiation Exposure and Cancer Risk Assessment: The Taiwan Nuclear Power Plants and Epidemiology Cohort Study (TNPECS).

BACKGROUND: This cohort was established to evaluate whether 38-year radiation exposure (since the start of nuclear reactor operations) is related to cancer risk in residents near three nuclear power plants (NPPs). METHODS: This cohort study enrolled all residents who lived within 8 km of any of the three NPPs in Taiwan from 1978 to 2016 (n = 214,502; person-years = 4,660,189). The control population (n = 257,475; person-years = 6,282,390) from three towns comprised all residents having lived more than 15 km from all three NPPs. Radiation exposure will be assessed via computer programs GASPAR-II and LADTAP-II by following methodologies provided in the United States Nuclear Regulatory Commission regulatory guides. We calculated the cumulative individual tissue organ equivalent dose and cumulative effective dose for each resident. This study presents the number of new cancer cases and prevalence in the residence-nearest NPP group and control group in the 38-year research observation period. CONCLUSION: TNPECS provides a valuable platform for research and opens unique possibilities for testing whether radiation exposure since the start of operations of nuclear reactors will affect health across the life course. The release of radioactive nuclear species caused by the operation of NPPs caused residents to have an effective dose between 10-7 and 10-3 mSv/year. The mean cumulative medical radiation exposure dose between the residence-nearest NPP group and the control group was not different (7.69; standard deviation, 18.39 mSv and 7.61; standard deviation, 19.17 mSv; P = 0.114).

Additive cardiotoxicity of a bisphenol mixture in zebrafish embryos: The involvement of calcium channel and pump.

Bisphenol A (BPA) and its analogs, such as bisphenol F (BPF), bisphenol AF (BPAF), and bisphenol B (BPB), are often simultaneously detected in environmental and human specimens. Thus, assessing the toxicity of bisphenol (BP) mixtures is more relevant than assessing that of each BP type. Here, we found that BPs, individually or in a mixture, concentration-dependently and additively increased the mortality of zebrafish embryos (ZFEs) at 96 h post fertilization (hpf) and induced bradycardia (i.e., reduced heart rate) at 48 hpf, indicating their cardiotoxic potency. BPAF was the most potent, followed by BPB, BPA, and BPF. We then explored the mechanism underlying BP-induced bradycardia in ZFEs. Although BPs increased the mRNA expression of the estrogen-responsive gene, treatment with the estrogen receptor inhibitor ICI 182780 did not prevent BP-induced bradycardia. Because they did not change cardiomyocyte counts or heart development-related gene expression, BPs might not affect cardiomyocyte development. By contrast, BPs might impair calcium homeostasis during cardiac contraction and relaxation through the downregulation of the expression of the mRNAs for the pore-forming subunit of L-type Ca2+ channel (LTCC; cacna1c) and sarco/endoplasmic reticulum Ca2+-ATPase (SERCA; atp2a2a). BPs reduced SERCA activity significantly. BPs also potentiated the cardiotoxicity induced by the LTCC blocker nisoldipine, conceivably by inhibiting SERCA activity. In conclusion, BPs additively induced bradycardia in ZFEs, possibly by impeding calcium homeostasis during cardiac contraction and relaxation. BPs also potentiated the cardiotoxicity of calcium channel blockers.

Worldwide serum concentration-based probabilistic mixture risk assessment of perfluoroalkyl substances among pregnant women, infants, and children.

Pregnant women, infants, and children are particularly vulnerable to perfluoroalkyl substances (PFASs), yet little is known about related health risks. Here, we aimed to study the four main PFASs: perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorohexanesulfonic acid (PFHxS), and assess the mixture risks of co-exposure to PFASs for pregnant women and children as well as for infants associated with maternal PFAS exposure at national and global scales, based on biomonitoring data on serum. We conducted a literature search and aggregated 69 data sources across 22 countries/regions from 2010 to 2020 to profile the serum concentrations of these four PFASs in pregnant women and children. Based on toxicity assessments by regulatory authorities, we determined conservative reference levels (RfLs) in the serum for the primary adverse effects of PFASs, including hepatic, developmental, and immune effects. The cumulative hazard quotient (HQ) was combined with probabilistic analysis to compare serum levels with RfLs and to quantify mixture risks. Our analysis revealed that PFOS was the dominant PFAS in maternal and child serum worldwide, with median levels 2.5-10 times higher than those of PFOA, PFNA, and PFHxS. The estimated global median serum levels of PFOS were 6.17 ng/mL for pregnant women and 4.85 ng/mL for children, and their immune effects in pregnant women and children are concerning as their cumulative HQs could exceed 1. For infants, the cumulative HQs for both developmental and immune effects could also be > 1, suggesting that maternal exposure to PFASs during pregnancy and breastfeeding may pose concerns for infant development and immunity. Our national and global serum database and risk assessment offer additional insights into PFAS exposures and mixture risks in susceptible populations, serving as a reference for evaluating the effectiveness of ongoing regulatory mitigation measures.

Analysis of Furan and Its Derivatives in Food Matrices Using Solid Phase Extraction Coupled with Gas Chromatography-Tandem Mass Spectrometry.

The objective of this study was to develop a simultaneous analysis method of furan and its 10 derivatives in different food commodities. The results indicated that furan and its 10 derivatives could be separated within 9.5 min by using a HP-5MS column and gas chromatography-tandem mass spectrometry (GC-MS/MS) with multiple reaction monitoring mode for detection. Furthermore, this method could resolve several furan isomers, such as 2-methyl furan and 3-methyl furan, as well as 2,3-dimethyl furan and 2,5-dimethyl furan. The most optimal extraction conditions were: 5 g of the fruit or juice sample mixed with 5 mL of the saturated NaCl solution, separately, or 1 g of the canned oily fish sample mixed with 9 mL of the saturated NaCl solution, followed by the equilibration of each sample at 35 °C for 15 min, using a carboxen-polydimethylsiloxane SPME arrow to adsorb the analytes for 15 min at 35 °C for subsequent analysis by GC-MS/MS. For method validation of all the analytes in the different food matrices, the recovery was 76-117% and the limit of the quantitation was 0.003-0.675 ng/g, while the relative standard deviation (RSD%) of the intra-day variability range from 1-16%, and that of the inter-day variability was from 4-20%. The method validation data further demonstrated that a reliable method was established for the analysis of furan and its 10 derivatives in commercial foods.

Assessment of potential human health risks in aquatic products based on the heavy metal hazard decision tree.

BACKGROUND: Naturally existing and human-produced heavy metals are released into the environment and cannot be completely decomposed by microorganisms, but they continue to accumulate in water and sediments, causing organisms to be exposed to heavy metals. RESULTS: This study designs and proposes heavy metal hazard decision trees for aquatic products, which are divided into seven categories including pelagic fishes, inshore fishes, other fishes, crustaceans, shellfish, cephalopods, and algae. Based on these classifications, representative fresh and processed seafood products are at the root of the heavy metal hazard decision trees. This study uses 2,107 cases of eating 556 cooked fresh or processed seafood product samples. The constructions of the proposed decision trees consist of 12 heavy metals, which include inorganic arsenic (iAs), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), strontium (Sr), thallium (Tl), and zinc (Zn). The heavy metal concentrations in cooked fresh and processed seafood product samples are subjected to a food safety risk assessment. CONCLUSIONS: The results indicate the relationships among the seven categories of aquatic products, the relationships among 12 heavy metals in aquatic products, and the relationships among potential human health risks. Finally, the proposed heavy metal hazard decision trees for aquatic products can be used as a reference model for researchers and engineers.

Ensemble learning for predicting ex vivo human placental barrier permeability.

BACKGROUND: The placental barrier protects the fetus from exposure to some toxicants and is vital for drug development and risk assessment of environmental chemicals. However, in vivo experiments for assessing the placental barrier permeability of chemicals is not ethically acceptable. Although ex vivo placental perfusion methods provide good alternatives for the assessment of placental barrier permeability, the application to a large number of test chemicals could be time- and resource-consuming. Computational prediction models for ex vivo placental barrier permeability are therefore desirable. METHODS: A total of 87 chemicals and corresponding 1444 physicochemical properties were divided into training and test datasets. Three types of algorithms including linear regression, random forest, and ensemble models were applied to develop prediction models for ex vivo placental barrier permeability. RESULTS: Among the tested models, the ensemble model integrating the previous two methods performed best for predicting ex vivo human placental barrier permeability with correlation coefficients of 0.887 and 0.825 when considering the applicability domain. An additional test on seven newly curated chemicals from the literature showed a good correlation coefficient of 0.879 which was further improved to 0.921 by considering the variation of experiments. CONCLUSION: In this study, the first valid predicting model for ex vivo human placental barrier permeability was developed following the OECD guideline. The model is expected to be useful for assessing the human placental barrier permeability and can be integrated with developmental toxicity prediction models for investigating the toxic effects of chemicals on the fetus.

Proximity to petrochemical industrial parks and risk of chronic glomerulonephritis.

This study determined whether individuals residing near petrochemical industrial parks (PIPs) have a higher risk of chronic glomerulonephritis (CGN). We performed population-based 1:4 case-control study by using Taiwan's National Health Insurance Research Database from 2000 to 2016. The subjects were aged 20-65 years, residing in western Taiwan, and did not have a history of any renal or urinary system disease in 2000. The case cohort included those who had at least three outpatient visits or one hospitalization between 2001 and 2016 with codes for CGN as per International Classification of Diseases (ICD)-Ninth and Tenth Revisions. Controls were randomly sampled age-, sex-, and urbanization-matched individuals without renal and urinary system diseases. Petrochemical exposure was evaluated by the distance to the nearest PIP of the residential township, and petrochemical exposure probability was examined considering the monthly prevailing wind direction. Conditional logistic regression was used to determine the association between petrochemical exposure and CGN risk. A total of 320,935 subjects were included in the final analysis (64,187 cases and 256,748 controls). After adjustment for potential confounders, living in townships within a 3-km radius of PIPs was associated with a higher risk of CGN (adjusted odds ratio [aOR] = 1.32, 95% confidence interval [CI] = 1.28-1.37). Compared with townships more than 20 km away from PIPs, those within 10 km of PIPs were associated with significantly increased risks of CGN in a dose-dependent manner. When prevailing wind was considered, townships with high exposure probability were associated with a significantly increased risk of CGN. We found that those residing near PIPs or with high petrochemical exposure probability had a higher risk of CGN. These findings highlight the need for monitoring environmental nephrotoxic substances and the renal health of residents living near PIPs.

Living proximity to petrochemical industries and the risk of attention-deficit/hyperactivity disorder in children.

Evidence regarding the negative neurodevelopmental effects of compound exposure to petrochemicals remains limited. We aimed to evaluate the association between exposure to petrochemical facilities and generated emissions during early life and the risk of attention-deficit/hyperactivity disorder (ADHD) development in children. We conducted a population-based birth cohort study using the 2004 to 2014 Taiwanese Birth Certificate Database and verified diagnoses of ADHD using the National Health Insurance Database. The level of petrochemical exposure in each participant's residential township was evaluated using the following 3 measurements: distance to the nearest petrochemical industrial plant (PIP), petrochemical exposure probability (accounting for monthly prevailing wind measurements), and monthly benzene concentrations estimated using kriging-based land-use regression models. We applied Cox proportional hazard models to evaluate the association. During the study period, 48,854 out of 1,863,963 children were diagnosed as having ADHD. The results revealed that residents of townships in close proximity to PIPs (hazard ratio [HR] = 1.20, 95% confidence interval [CI]: 1.16-1.23, <3 vs. ≥10 km), highly affected by petrochemical-containing prevailing winds (HR = 1.12, 95% CI: 1.08-1.16, ≥40% vs. <10%), and with high benzene concentrations (HR = 1.26, 95% CI: 1.23-1.29, ≥0.75 vs. <0.55 ppb) were consistently associated with the increased risk of ADHD development in children. The findings of the sensitivity analysis remained robust, particularly for the 2004 to 2009 birth cohort and for models accounting for a longer duration of postnatal exposure. This work provided clear evidence that living near petrochemical plants increases the risk of ADHD development in children. Further studies are warranted to confirm our findings.

Aryl hydrocarbon receptor activation-mediated vascular toxicity of ambient fine particulate matter: contribution of polycyclic aromatic hydrocarbons and osteopontin as a biomarker.

BACKGROUND: Exposure to ambient fine particulate matter (PM2.5) is associated with vascular diseases. Polycyclic aromatic hydrocarbons (PAHs) in PM2.5 are highly hazardous; however, the contribution of PM2.5-bound PAHs to PM2.5-associated vascular diseases remains unclear. The ToxCast high-throughput in vitro screening database indicates that some PM2.5-bound PAHs activate the aryl hydrocarbon receptor (AhR). The present study investigated whether the AhR pathway is involved in the mechanism of PM2.5-induced vascular toxicity, identified the PAH in PM2.5 that was the major contributor of AhR activation, and identified a biomarker for vascular toxicity of PM2.5-bound PAHs. RESULTS: Treatment of vascular smooth muscle cells (VMSCs) with an AhR antagonist inhibited the PM2.5-induced increase in the cell migration ability; NF-κB activity; and expression of cytochrome P450 1A1 (CYP1A1), 1B1 (CYP1B1), interleukin-6 (IL-6), and osteopontin (OPN). Most PM2.5-bound PAHs were extracted into the organic fraction, which drastically enhanced VSMC migration and increased mRNA levels of CYP1A1, CYP1B1, IL-6, and OPN. However, the inorganic fraction of PM2.5 moderately enhanced VSMC migration and only increased IL-6 mRNA levels. PM2.5 increased IL-6 secretion through NF-κB activation; however, PM2.5 and its organic extract increased OPN secretion in a CYP1B1-dependent manner. Inhibiting CYP1B1 activity and silencing OPN expression prevented the increase in VSMC migration ability caused by PM2.5 and its organic extract. The AhR activation potencies of seven PM2.5-bound PAHs, reported in the ToxCast database, were strongly correlated with their capabilities of enhancing the migration ability of VSMCs. Benzo(k)fluoranthene (BkF) contributed the most to the AhR agonistic activity of ambient PM2.5-bound PAHs. The association between PM2.5-induced vascular toxicity, AhR activity, and OPN secretion was further verified in mice; PM2.5-induced intimal hyperplasia in pulmonary small arteries and OPN secretion were alleviated in mice with low AhR affinity. Finally, urinary concentrations of 1-hydroxypyrene, a major PAH metabolite, were positively correlated with plasma OPN levels in healthy humans. CONCLUSIONS: The present study offers in vitro, animal, and human evidences supporting the importance of AhR activation for PM2.5-induced vascular toxicities and that BkF was the major contributor of AhR activation. OPN is an AhR-dependent biomarker of PM2.5-induced vascular toxicity. The AhR activation potency may be applied in the risk assessment of vascular toxicity in PAH mixtures.

Maternal proximity to petrochemical industrial parks and risk of premature rupture of membranes.

BACKGROUND: Living near petrochemical industries has been reported to increase the risks of adverse birth outcomes, such as low birth weight and preterm delivery. However, evidence regarding the role of petrochemical exposure in pregnancy complications remains limited. This study evaluated the association between maternal proximity to petrochemical industrial parks (PIPs) during pregnancy and the occurrence of premature rupture of membranes (PROM). METHODS: We performed a population-based 1:3 case-control study by using the 2004-2014 Taiwanese Birth Certificate Database. Birth records reported as stillbirth or bearing congenital anomalies were excluded. Cases were newborns reported to have PROM, whereas controls were randomly sampled from those without any pregnancy complications by matching birth year and urbanization index of the residential township. The proximity to PIPs was evaluated by calculating the distance to the nearest PIP of the maternal residential township during pregnancy. Furthermore, petrochemical exposure opportunity, accounting for monthly prevailing wind direction, was quantified during the entire gestational period. We applied conditional logistic regression models to evaluate the associations. RESULTS: In total, 29371 PROM cases were reported during the study period, with a corresponding 88113 healthy controls sampled. The results revealed that living within a 3-km radius of PIPs during pregnancy would increase the risk of PROM (odds ratio [OR] = 1.76, 95% CI: 1.66-1.87). Furthermore, compared with the lowest exposed group, those with high petrochemical exposure opportunity had a significantly increased risk of PROM occurrence (OR = 1.69-1.75). The adverse effects remained robust in the subgroup analysis for both term- and preterm-PROM. CONCLUSIONS: The results of the present work provide evidence that living near PIPs during pregnancy would increase the risk of PROM, and additional studies are warranted to confirm our findings.

Conditioned Media of Adipose-Derived Stem Cells Suppresses Sidestream Cigarette Smoke Extract Induced Cell Death and Epithelial-Mesenchymal Transition in Lung Epithelial Cells.

The role of the epithelial-mesenchymal transition (EMT) in lung epithelial cells is increasingly being recognized as a key stage in the development of COPD, fibrosis, and lung cancers, which are all highly associated with cigarette smoking and with exposure to second-hand smoke. Using the exposure of human lung cancer epithelial A549 cells and non-cancerous Beas-2B cells to sidestream cigarette smoke extract (CSE) as a model, we studied the protective effects of adipose-derived stem cell-conditioned medium (ADSC-CM) against CSE-induced cell death and EMT. CSE dose-dependently induced cell death, decreased epithelial markers, and increased the expression of mesenchymal markers. Upstream regulator analysis of differentially expressed genes after CSE exposure revealed similar pathways as those observed in typical EMT induced by TGF-ß1. CSE-induced cell death was clearly attenuated by ADSC-CM but not by other control media, such as a pass-through fraction of ADSC-CM or A549-CM. ADSC-CM effectively inhibited CSE-induced EMT and was able to reverse the gradual loss of epithelial marker expression associated with TGF-ß1 treatment. CSE or TGF-ß1 enhanced the speed of A549 migration by 2- to 3-fold, and ADSC-CM was effective in blocking the cell migration induced by either agent. Future work will build on the results of this in vitro study by defining the molecular mechanisms through which ADSC-CM protects lung epithelial cells from EMT induced by toxicants in second-hand smoke.

Leveraging complementary computational models for prioritizing chemicals of developmental and reproductive toxicity concern: an example of food contact materials.

The evaluation of developmental and reproductive toxicity of food contact materials (FCMs) is an important task for food safety. Since traditional experiments are both time-consuming and labor-intensive, only a small number of FCMs have sufficient toxicological data for evaluating their effects on human health. While computational methods such as structural alerts and quantitative structure-activity relationships can serve as first-line tools for the identification of chemicals of high toxicity concern, models with binary outputs and unsatisfied accuracy and coverage prevent the use of computational methods for prioritizing chemicals of high concern. This study proposed a genetic algorithm-based method to develop a weight-of-evidence (WoE) model leveraging complementary methods of structural alerts, quantitative structure-activity relationships and in silico toxicogenomics models for chemical prioritization. The WoE model was applied to evaluate 623 food contact chemicals and identify 26 chemicals of high toxicity concern, where 13 chemicals have been reported to be developmental or reproductive toxic and further experiments are suggested for the remaining 13 chemicals without toxicity data related to developmental and reproductive effects. The proposed WoE model is potentially useful for prioritizing chemicals of high toxicity concern and the methodology may be applied to toxicities other than developmental and reproductive toxicity.

Exposure to Zinc Oxide Nanoparticles Disrupts Endothelial Tight and Adherens Junctions and Induces Pulmonary Inflammatory Cell Infiltration.

Zinc oxide nanoparticles (ZnONPs) are frequently encountered nanomaterials in our daily lives. Despite the benefits of ZnONPs in a variety of applications, many studies have shown potential health hazards of exposure to ZnONPs. We have shown that oropharyngeal aspiration of ZnONPs in mice increases lung inflammation. However, the detailed mechanisms underlying pulmonary inflammatory cell infiltration remain to be elucidated. Endothelium functions as a barrier between the blood stream and the blood vessel wall. Endothelial barrier dysfunction may increase infiltration of immune cells into the vessel wall and underlying tissues. This current study examined the effects of ZnONPs exposure on endothelial barriers. ZnONPs exposure increased leukocyte infiltration in the mouse lungs. In endothelial cells, ZnONPs reduced the continuity of tight junction proteins claudin-5 and zonula occludens-1 (ZO-1) at the cell junctions. ZnONPs induced adherens junction protein VE-cadherin internalization from membrane to cytosol and dissociation with ß-catenin, leading to reduced and diffused staining of VE-cadherin and ß-catenin at cell junctions. Our results demonstrated that ZnONPs disrupted both tight and adherens junctions, compromising the integrity and stability of the junction network, leading to inflammatory cell infiltration. Thus, ZnONPs exposure in many different settings should be carefully evaluated for vascular effects and subsequent health impacts.

Probabilistic Integrated Human Mixture Risk Assessment of Multiple Metals Through Seafood Consumption.

Inorganic arsenic (iAs), cadmium (Cd), lead (Pb), and methylmercury (MeHg) are toxic metals that cause substantial health concern and are present in various seafood items. This study linked probabilistic risk assessment to the interactive hazard index (HIINT ) approach to assess the human mixture risk posed by the dietary intake of iAs, Cd, Pb, and MeHg from seafood for different age populations, and joint toxic actions and toxic interactions among metals were also considered in the assessment. We found that, in combination, an iAs-Cd-Pb-MeHg mixture synergistically causes neurological toxicity. Furthermore, an iAs-Cd-Pb mixture antagonistically causes renal and hematological effects and additively causes cardiovascular effect. Our results demonstrated that if toxic interactions are not considered, the health risk may be overestimated or underestimated. The 50th percentile HIINT estimates in all age populations for neurological, renal, cardiovascular, and hematological effects were lower than 1; however, the 97.5th percentile HIINT estimates might exceed 1. In particular, toddlers and preschoolers had the highest neurological risk, with 0.16 and 0.19 probabilities, respectively, of neurological HIINT exceeding 1. Saltwater fish consumption was the principal contributor to the health risk. We suggest that regular monitoring of metal levels in seafood, more precise dietary surveys, further toxicological data, and risk-benefit analysis of seafood consumption are warranted to improve the accuracy of human mixture risk assessment and determine optimal consumption.

Persistent elevation of blood pressure by ambient coarse particulate matter after recovery from pulmonary inflammation in mice.

Exposure to ambient particulate matter (PM) is associated with hypertension and cardiovascular diseases. Recently, we reported that exposure to fine and coarse PM caused pulmonary inflammation and pulmonary small arterial remodeling in mice, and osteopontin (OPN) level was elevated following PM exposure. However, in the present study, cotreatment with 5-methoxytryptophan for 4 weeks partially reduced coarse PM-induced pulmonary inflammation without reducing pulmonary OPN secretion or recovery from pulmonary arterial remodeling in mice. Persistent vascular dysfunction may lead to vascular remodeling. Therefore, we further compared the relationship between coarse PM-induced inflammation and vascular dysfunction by exposing mice to PM before and after cessation of PM exposure. Oropharyngeal aspiration of PM for 8 weeks induced pulmonary inflammation and pulmonary small artery remodeling in mice, as well as increased serum C-reactive protein and OPN concentrations and systolic blood pressure (SBP). After the cessation of PM exposure for another 8 weeks, lung inflammation had recovered and vascular remodeling had partially recovered. Elevation of OPN, metalloproteinases (MMPs), and cytokines in bronchioalveolar lavage were significantly reduced. However, PM-induced systemic responses did not recover after the cessation of PM exposure. Notably, not only serum OPN and SBP remained significantly elevated; also, serum endothelin-1, MMP-9, and keratinocyte-derived chemokine concentrations were significantly increased after cessation of PM exposure for another 8 weeks. These data suggested that systemic inflammation and systemic vascular dysfunction might be important in PM-induced elevation of SBP. Furthermore, SBP elevation was persistent after cessation of PM exposure for 8 weeks.

Vanadium Derivative Exposure Promotes Functional Alterations of VSMCs and Consequent Atherosclerosis via ROS/p38/NF-κB-Mediated IL-6 Production.

Vanadium is a transition metal widely distributed in the Earth's crust, and is a major contaminant in fossil fuels. Its pathological effect and regulation in atherosclerosis remain unclear. We found that intranasal administration of the vanadium derivative NaVO3 significantly increased plasma and urinary vanadium levels and induced arterial lipid accumulation and atherosclerotic lesions in apolipoprotein E-deficient knockout mice (ApoE-/-) murine aorta compared to those in vehicle-exposed mice. This was accompanied by an increase in plasma reactive oxygen species (ROS) and interleukin 6 (IL-6) levels and a decrease in the vascular smooth muscle cell (VSMC) differentiation marker protein SM22α in the atherosclerotic lesions. Furthermore, exposure to NaVO3 or VOSO4 induced cytosolic ROS generation and IL-6 production in VSMCs and promoted VSMC synthetic differentiation, migration, and proliferation. The anti-oxidant N-acetylcysteine (NAC) not only suppresses IL-6 production and VSMC pathological responses including migration and proliferation but also prevents atherosclerosis in ApoE-/- mice. Inhibition experiments with NAC and pharmacological inhibitors demonstrated that NaVO3-induced IL-6 production is signaled by ROS-triggered p38-mediated NF-κB-dependent pathways. Neutralizing anti-IL-6 antibodies impaired NaVO3-mediated VSMC migration and proliferation. We concluded that NaVO3 exposure activates the ROS-triggering p38 signaling to selectively induce NF-κB-mediated IL-6 production. These signaling pathways induce VSMC synthetic differentiation, migration, and proliferation, leading to lipid accumulation and atherosclerosis.

A histone deacetylase inhibitor enhances expression of genes inhibiting Wnt pathway and augments activity of DNA demethylation reagent against nonsmall-cell lung cancer.

Development of new inhibitors targeting histone deacetylases (HDACs) with improved efficacy for solid tumor therapy is urgently needed. Here, we report the development of a novel HDAC inhibitor TMU-35435 and verify it as a single agent and in combination treatment with DNA demethylation reagent 5-aza-2'-deoxycytidine (5-aza-dC) in lung cancer preclinical models. TMU-35435 exerted cancer-specific cytotoxicity via mitochondria-mediated apoptosis. Expression microarrays revealed a unique TMU-35435-induced gene networks enriched in biological processes, including "negative regulation of cell proliferation" and "Wnt receptor signaling pathway" compared to FDA-approved HDAC inhibitor SAHA. TMU-35435 inhibited tumor growth with good pharmacokinetic properties and safety features in lung orthotopic and subcutaneously implanted xenograft models. TMU-35435 and 5-aza-dC showed synergistic antitumor effects through reactivation of tumor suppressor genes and those genes encoding negative regulators of Wnt signaling pathway in vitro and in vivo. Some genes showed additive inhibition of DNA methylation upon TMU-35435 and 5-aza-dC combined treatment. Our findings suggested that TMU-35435 is a potential HDAC inhibitor for lung cancer treatment as a single agent and in combination with 5-aza-dC.

Interleukin-24 as a target cytokine of environmental aryl hydrocarbon receptor agonist exposure in the lung.

Exposure to environmental aryl hydrocarbon receptor (AhR) agonists, such as halogenated aromatic hydrocarbons and polycyclic aromatic hydrocarbons (PAHs), has great impacts on the development of various lung diseases. As emerging molecular targets for AhR agonists, cytokines may contribute to the inflammatory or immunotoxic effects of environmental AhR agonists. However, general cytokine expression may not specifically indicate environmental AhR agonist exposure. By comparing cytokine and chemokine expression profiles in human lung adenocarcinoma cell line CL5 treated with AhR agonists and the non-AhR agonist polychlorinated biphenyl (PCB) 39, we identified a target cytokine of environmental AhR agonist exposure of in the lungs. Thirteen cytokine and chemokine genes were altered in the AhR agonists-treated cells, but none were altered in the PCB39-treated cells. Interleukin (IL)-24 was the most highly induced gene among AhR-modulated cytokines. Cotreatment with AhR antagonist completely prevented IL-24 induction by AhR agonists in the CL5 cells. Knockdown AhR expression with short-hairpin RNA (shRNA) significantly reduced benzo[a]pyrene (BaP)-induced IL-24 mRNA levels. We further confirmed that gene transcription, but not mRNA stability, was involved in IL-24 upregulation by BaP. Particulate matter (PM) in the ambient air contains some PAHs and is reported to activate AhR. Oropharyngeal aspiration of PM significantly increased IL-24 levels in lung epithelia and in bronchoalveolar lavage fluid of mice 4weeks after treatment. Thus, our data suggests that IL-24 is a pulmonary exposure target cytokine of environmental AhR agonists.