Faculty Bibliography

In this unit, the need for laboratory-based inhalation toxicology studies, the historical background on adverse health effects of airborne toxicants, and the benefits of advance planning for the building of analytic options into the study design to maximize the scientific gains to be derived from the investments in the study are outlined. The following methods are described: (1) the generation and characterization of exposure atmospheres for inhalation exposures in humans and laboratory animals; (2) the delivery and distribution into and within whole-body exposure chambers, head-only exposure chambers, face-masks, and mouthpieces or nasal catheters; (3) options for on-line functional assays during and between exposures; and (4) options for serial non-invasive assays of response. In doing so, a description beyond exposures to single agents and simple mixtures is presented, and included are methods for evaluating biological responses to complex environmental mixtures. It is also emphasized that great care should be taken in the design and execution of such studies so that the scientific returns can be maximized both initially, and in follow-up utilization of archived samples of the exposure atmospheres, excreta, and tissues collected for histology. (c) 2015 by John Wiley & Sons, Inc.

Abstract Comparing effects of inhaled particles across rodent test systems and between rodent test systems and humans is a key obstacle to the interpretation of common toxicological test systems for human risk assessment. These comparisons, correlation with effects and prediction of effects, are best conducted using measures of tissue dose in the respiratory tract. Differences in lung geometry, physiology and the characteristics of ventilation can give rise to differences in the regional deposition of particles in the lung in these species. Differences in regional lung tissue doses cannot currently be measured experimentally. Regional lung tissue dosimetry can however be predicted using models developed for rats, monkeys, and humans. A computational model of particle respiratory tract deposition and clearance was developed for BALB/c and B6C3F1 mice, creating a cross-species suite of available models for particle dosimetry in the lung. Airflow and particle transport equations were solved throughout the respiratory tract of these mice strains to obtain temporal and spatial concentration of inhaled particles from which deposition fractions were determined. Particle inhalability (Inhalable fraction, IF) and upper respiratory tract (URT) deposition were directly related to particle diffusive and inertial properties. Measurements of the retained mass at several post-exposure times following exposure to iron oxide nanoparticles, micro- and nanoscale C60 fullerene, and nanoscale silver particles were used to calibrate and verify model predictions of total lung dose. Interstrain (mice) and interspecies (mouse, rat and human) differences in particle inhalability, fractional deposition and tissue dosimetry are described for ultrafine, fine and coarse particles.

RATIONALE: Air pollution exposure has been shown to potentiate plaque progression in humans and animals. Our previous studies have suggested a role for oxidized lipids in mediating adverse vascular effect of air pollution. However, the types of oxidized lipids formed in response to air pollutants and how this occurs and their relevance to atherosclerosis are not fully understood. OBJECTIVE: To investigate the mechanisms by which particulate matter <2.5 mum (PM2.5) induces progression of atherosclerosis. METHODS AND RESULTS: Atherosclerosis-prone ApoE(-/-) or LDLR(-/-) mice were exposed to filtered air or concentrated ambient PM2.5 using a versatile aerosol concentrator enrichment system for 6 months. PM2.5 increased 7-ketocholesterol (7-KCh), an oxidatively modified form of cholesterol, in plasma intermediate density lipoprotein/low-density lipoprotein fraction and in aortic plaque concomitant with progression of atherosclerosis and increased CD36 expression in plaque macrophages from PM2.5-exposed mice. Macrophages isolated from PM2.5-exposed mice displayed increased uptake of oxidized lipids without alterations in their efflux capacity. Consistent with these finding, CD36-positive macrophages displayed a heightened capacity for oxidized lipid uptake. Deficiency of CD36 on hematopoietic cells diminished the effect of air pollution on 7-KCh accumulation, foam cell formation, and atherosclerosis. CONCLUSIONS: Our results suggest a potential role for CD36-mediated abnormal accumulations of oxidized lipids, such as 7-KCh, in air pollution-induced atherosclerosis progression.

Abstract Introduction: The discovery of endothelial progenitor cells (EPCs) may help to explain observed cardiovascular effects associated with inhaled nickel nanoparticle exposures, such as increases in vascular inflammation, generation of reactive oxygen species, altered vasomotor tone and potentiated atherosclerosis in murine species. METHODS: Following an acute whole body inhalation exposure to 500 microg/m(3) of nickel nanoparticles for 5 h, bone marrow EPCs from C57BL/6 mice were isolated. EPCs were harvested for their RNA or used in a variety of assays including chemotaxis, tube formation and proliferation. Gene expression was assessed for important receptors involved in EPC mobilization and homing using RT-PCR methods. EPCs, circulating endothelial progenitor cells (CEPCs), circulating endothelial cells (CECs) and endothelial microparticles (EMPs) were quantified on a BD FACSCalibur to examine endothelial damage and repair associated with the exposure. RESULTS AND CONCLUSIONS: Acute exposure to inhaled nickel nanoparticles significantly increased both bone marrow EPCs as well as their levels in circulation (CEPCs). CECs were significantly elevated indicating that endothelial damage occurred due to the exposure. There was no significant difference in EMPs between the two groups. Tube formation and chemotaxis, but not proliferation, of bone marrow EPCs was impaired in the nickel nanoparticle exposed group. These results coincided with a decrease in the mRNA of receptors involved in EPC mobilization and homing. These data provide new insight into how an acute nickel nanoparticle exposure to half of the current Occupational Safety & Health Administration (OSHA) permissible exposure limit may adversely affect EPCs and exacerbate cardiovascular disease states.

Airborne particulate matter (PM) exposure is a major environmental health concern and is linked to metabolic disorders, such as cardiovascular diseases (CVD) and diabetes, which are on the rise in the Kingdom of Saudi Arabia. This study investigated changes in mouse lung gene expression produced by administration of PM10 collected from Jeddah, Saudi Arabia. FVB/N mice were exposed to 100 mug PM10 or water by aspiration and euthanized 24 h later. The bronchoalveolar lavage fluid (BALF) was collected and analyzed for neutrophil concentration and tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 levels. RNA was extracted from lungs and whole transcript was analyzed using Affymetrix Mouse Gene 1.0 ST Array. Mice exposed to PM10 displayed an increase in neutrophil concentration and elevated TNF-alpha and IL-6 levels. Gene expression analysis revealed that mice exposed to PM10 displayed 202 genes that were significantly upregulated and 40 genes that were significantly downregulated. PM10 induced genes involved in inflammation, cholesterol and lipid metabolism, and atherosclerosis. This is the first study to demonstrate that Saudi Arabia PM10 increases in vivo expression of genes located in pathways associated with diseases involving metabolic syndrome and atherosclerosis.

BACKGROUND: Industrialization in the northwest provinces of the People's Republic of China is accelerating rapid increases in early life environmental exposures, yet no publications have assessed health care provider capacity to manage common hazards. METHODS: To assess provider attitudes and beliefs regarding the environment in children's health, determine self-efficacy in managing concerns, and identify common approaches to managing patients with significant exposures or environmentally-mediated conditions, a two-page survey was administered to pediatricians, child care specialists, and nurses in five provinces (Gansu, Shaanxi, Xinjiang, Qinghai, and Ningxia). Descriptive and multivariable analyses assessed predictors of strong self-efficacy, beliefs or attitudes. RESULTS: 960 surveys were completed with <5% refusal; 695 (72.3%) were valid for statistical analyses. The role of environment in health was rated highly (mean 4.35 on a 1-5 scale). Self-efficacy reported with managing lead, pesticide, air pollution, mercury, mold and polychlorinated biphenyl exposures were generally modest (2.22-2.52 mean). 95.4% reported patients affected with 11.9% reporting seeing >20 affected patients. Only 12.0% reported specific training in environmental history taking, and 12.0% reported owning a text on children's environmental health. Geographic disparities were most prominent in multivariable analyses, with stronger beliefs in environmental causation yet lower self-efficacy in managing exposures in the northwestern-most province. CONCLUSIONS: Health care providers in Northwest China have strong beliefs regarding the role of environment in children's health, and frequently identify affected children. Few are trained in environmental history taking or rate self-efficacy highly in managing common hazards. Enhancing provider capacity has promise for improving children's health in the region.

First responders (FRs) present at Ground Zero within the critical first 72 h after the World Trade Center (WTC) collapse have progressively exhibited significant respiratory injury. The majority (>96%) of WTC dusts were >10 mum and no studies have examined potential health effects of this size fraction. This study sought to develop a system to generate and deliver supercoarse (10-53 mum) WTC particles to a rat model in a manner that mimicked FR exposure scenarios. A modified Fishing Line generator was integrated onto an intratracheal inhalation (ITIH) system that allowed for a bypassing of the nasal passages so as to mimic FR exposures. Dust concentrations were measured gravimetrically; particle size distribution was measured via elutriation. Results indicate that the system could produce dusts with 23 mum mass median aerodynamic diameter (MMAD) at levels up to >/=1200 mg/m(3). To validate system utility, F344 rats were exposed for 2 h to approximately 100 mg WTC dust/m(3). Exposed rats had significantly increased lung weight and levels of select tracer metals 1 h after exposure. Using this system, it is now possible to conduct relevant inhalation exposures to determine adverse WTC dusts impacts on the respiratory system. Furthermore, this novel integrated Fishing Line-ITIH system could potentially be used in the analyses of a wide spectrum of other dusts/pollutants of sizes previously untested or delivered to the lungs in ways that did not reflect realistic exposure scenarios.

OBJECTIVES: Studies have shown that chronic exposure to ambient fine particulate matter (less than 2.5 microm in aerodynamic diameter, PM(2).(5)) pollution induces insulin resistance through alterations in inflammatory pathways. It is critical to study how the immune system responds to this stimulant, which has been linked to cardiovascular and autoimmune diseases, but few studies have been focused on such involvement of both neutrophils and monocytes in a timely manner. We hypothesized that the neutrophil was involved in the inflammatory response to air pollution. METHODS AND RESULTS: C57BL/6 mice were exposed to PM(2).(5) or filtered air (6 hours/day, 5 days/week) for 5, 14, and 21 days, respectively, in Columbus, OH. At the end of each of the exposure periods, we investigated the inflammatory response through flow cytometry, histology, intravital microscopy, and real-time PCR. PM(2).(5)-exposed mice demonstrated a significant inflammatory response after 5 days of exposure. In the lung tissue and bronchoalveolar lavage fluid, monocytes/macrophages showed a transient response, while neutrophils showed a cumulative response. In addition, exposure to PM(2).(5) resulted in elevation of the monocyte chemoattractant protein 1 (MCP-1) cytokine, a monocyte/macrophage attractant in blood, at an early stage of exposure. CONCLUSIONS: These findings suggest that PM(2).(5) exposure induces the inflammatory responses from both macrophages and neutrophils involvement.

Particulate matter (PM*), an ambient air criteria pollutant, is a complex mixture of chemical components; particle sizes range from nanometer-sized molecular clusters to dust particles that are too large to be aspirated into the lungs. Although particle composition is believed to affect health risks from PM exposure, our current health-based air quality standards for PM are limited to (1) the mass concentrations of PM2.5 (particles 2.5 microm or smaller in aerodynamic diameter), which are largely attributable to combustion products; and (2) PM10 (10 microm or smaller), which includes larger-sized mechanically generated dusts. Both of these particle size fractions are regulated under the National Ambient Air Quality Standards (NAAQS) and both have been associated with excess mortality and morbidity. We conducted four studies as part of HEI's integrated National Particle Component Toxicity (NPACT) Initiative research program. Since 1999, the Chemical Speciation Network (CSN), managed by the U.S. Environmental Protection Agency (U.S; EPA), has routinely gathered air monitoring data every third or sixth day for the concentrations of numerous components of PM2.5. Data from the CSN enabled us to conduct a limited time-series epidemiologic study of short-term morbidity and mortality (Ito study); and a study of the associations between long-term average pollutant concentrations and annual mortality (Thurston study). Both have illuminated the roles of PM2.5 chemical components and source-related mixtures as potentially causal agents. We also conducted a series of 6-month subchronic inhalation exposure studies (6 hours/day, 5 days/week) of PM2.5 concentrated (nominally) 10 x from ambient air (CAPs) with apolipoprotein E-deficient (ApoE(-/-)) mice (a mouse model of atherosclerosis) (Chen study). The CAPs studies were conducted in five different U.S. airsheds; we measured the daily mass concentrations of PM2.5, black carbon (BC), and 16 elemental components in order to identify their sources and their roles in eliciting both short- and long-term health-related responses. In addition, from the same five air-sheds we collected samples of coarse (PM10-2.5), fine (PM2.5-0.2), and ultrafine (PM0.2) particles. Aliquots of these samples were administered to cells in vitro and to mouse lungs in vivo (by aspiration) in order to determine their comparative acute effects (Gordon Study). The results of these four complementary studies, and the overall integrative analyses, provide a basis for guiding future research and for helping to determine more targeted emission controls for the PM components most hazardous to acute and chronic health. Application of the knowledge gained in this work may therefore contribute to an optimization of the public health benefits of future PM emission controls. The design of each NPACT study conducted at NYU was guided by our scientific hypotheses, which were based on our reviews of the background literature and our experience in conducting studies of associations between ambient PM and health-related responses. These hypotheses guided the development and conduct of the four studies. Hypothesis 1. Coarse, fine, and ultrafine PM are each capable of producing acute health effects of public health concern, but the effects may differ according to particle size and composition. (Applies to all studies.) Hypothesis 2. Long-term PM2.5 exposures are closely associated with chronic health effects. (Applies to studies 1 and 4.) Hypothesis 3. The source-apportionment techniques that we have developed and refined in recent years provide a useful basis for identifying major categories of sources of PM in ambient air and specific chemical components that have the greatest impacts on a variety of acute and chronic health effects. (Applies to all studies.) Hypothesis 4. The health effects due to ambient PM exposures can best be seen in sensitive subgroups within overall human populations and in animal models of such populations. (Applies to studies 1, 3, and 4.) Overall, the studies have demonstrated that the toxicity of PM is driven by a complex interaction of particle size range, geographic location, source category, and season. These findings suggest that the components of PM--associated with certain categories of sources--are responsible for the observed adverse health effects. Most importantly, the responsible components and source categories vary with the health-related endpoints being assessed. Across all studies, fossil-fuel combustion source categories were most consistently associated with both short- and long-term adverse effects of PM2.5 exposure. The components that originate from the Residual Oil Combustion and Traffic source categories were most closely associated with short-term effects; and components from the Coal Combustion category were more closely associated with long-term effects.

Exposure to ambient fine particulate matter (PM2.5) increases risks for cardiovascular disorders (CVD). However, the mechanisms and components responsible for the effects are poorly understood. Based on our previous murine exposure studies, a translational pilot study was conducted in female residents of Jinchang and Zhangye, China, to test the hypothesis that specific chemical component of PM2.5 is responsible for PM2.5 associated CVD. Daily ambient and personal exposures to PM2.5 and 35 elements were measured in the two cities. A total of 60 healthy nonsmoking adult women residents were recruited for measurements of inflammation biomarkers. In addition, circulating endothelial progenitor cells (CEPCs) were also measured in 20 subjects. The ambient levels of PM2.5 were comparable between Jinchang and Zhangye (47.4 and 54.5microg/m(3), respectively). However, the levels of nickel, copper, arsenic, and selenium in Jinchang were 82, 26, 12, and 6 fold higher than Zhangye, respectively. The levels of C-reactive protein (3.44+/-3.46 vs. 1.55+/-1.13), interleukin-6 (1.65+/-1.17 vs. 1.09+/-0.60), and vascular endothelial growth factor (117.6+/-217.0 vs. 22.7+/-21.3) were significantly higher in Jinchang. Furthermore, all phenotypes of CEPCs were significantly lower in subjects recruited from Jinchang than those from Zhangye. These results suggest that specific metals may be important components responsible for PM2.5-induced cardiovascular effects and that the reduced capacity of endothelial repair may play a critical role.