? Data for performing a preliminary risk assessment of manufactured nanomaterials are just beginning to emerge. However, early studies of nanomaterial toxicity in aqueous media have tended to be more observational than mechanistic, and have often focused on a single, advanced stage of toxicity that could yield contradictory results. Moreover, the ability to generalize findings to other nanomaterials is limited by the lack of a rational basis for categorizing nanomaterials. Elucidating the mechanisms of toxicity for a given nanomaterial will provide a basis for classifying materials for regulatory purposes, postulating dose-response curves, screening potential risks, and prescribing strategies for risk management. The primary objective of this work is to elucidate the mechanism(s) by which manufactured nanoparticles may induce toxicity in vitro and in vivo. Specifically, this study will consider fullerene-based materials, comparing them with, (i) reference standards (TiO2 and carbon black); (ii) ultrafine particles obtained from an urban airshed (well characterized by in vitro toxicology studies); We will explore a methodology for rapidly screening potentially toxic nanoparticles based on their propensity to generate ROS. The principal hypothesis is that certain classes of nanoparticles such as fullerenes induce ROS production, cellular oxidative stress and cytotoxicity. Fullerenes are selected based on the relatively novel properties (e.g. strength.arid electron affinity) that make them attractive for commercialization. The investigators propose that oxidative stress induced by fullerene derivatives occurs in several stages (tiers), beginning with the induction of phase II antioxidant defenses at the lowest tier of oxidative stress (tier 1), followed by pro-inflammatory (tier 2) and mitochondrion-mediated cytotoxic effects (tier 3) as the level of oxidative stress increases. Particle size, shape, surface area, charge, and chemical composition are important physical variables that could determine their ROS-generating or scavenging properties. Rapid physicochemical determination of ROS production might provide a paradigm to assess the possible toxicity of nanomaterials that act via these mechanisms. ? ? Specific Aim 1 will characterize commercial nanoparticles and their derivatives in terms of particle size, shape, surface area, charge, aqueous solubility, propensity to aggregate, and their ability to catalyze or quench ROS production in vitro. Materials will also be characterized in model solutions containing naturally occurring organic matter, proteins and ions at levels similar to those present in natural waters.
Aim 2 will determine whether various fullerenes can generate a hierarchical oxidative stress response in macrophages, bronchial epithelial cells, endothelial cells, neural cells and hepatocytes. This will be accomplished by comparing the effects of fullerenes and reference nanoparticles on, (i) phase II enzyme expression and activation of the heme oxygenase 1 (HO-1) promoter (tier 1); (ii) cytokine and chernokine expression as well as assays for MAP kinase activation (tier 2); (iii) mitochondria! perturbation and induction of cellular apoptosis (tier 3). These biological responses will be compared to the physicochemieal properties of nanomaterials elucidated in Aim 1.
Aim 3 will perform in vivo imaging of the oxidative stress-sensitive HO-1 promoter linked to a luciferase reporter in transgenic mice. Organs and tissues showing increased luciferase activity will be investigated for histological evidence of inflammation and cytotoxicity.
Aim 4 will compare the biologic responses elicited by each of the nano-scale particles with their ability to generate ROS abiotically, and test the hypothesis that ROS generation can be used to screen toxicity. ? ? By focusing on mechanisms of toxicity rather than outcomes alone, this work will provide the basis for classifying nanomaterials for regulatory purposes. Based on preliminary results presented in this proposal, we anticipate that ROS generation in solution and under UV radiation will be good predictors of nanoparticle toxicity and that ROS measurements can be adapted to screen nanomaterials. A broader assessment of nanomaterial toxicity in the context of the hierarchical oxidative stress response is likely to yield a more sensitive paradigm for toxicity testing, perhaps resolving inconsistencies reported in the literature. ? ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Research Project (R01)
Project #
5R01ES015498-02
Application #
7290383
Study Section
Special Emphasis Panel (ZES1-SET-D (D1))
Program Officer
Nadadur, Srikanth
Project Start
2006-09-30
Project End
2009-06-30
Budget Start
2007-07-01
Budget End
2008-06-30
Support Year
2
Fiscal Year
2007
Total Cost
$126,342
Indirect Cost
Name
University of California Los Angeles
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
092530369
City
Los Angeles
State
CA
Country
United States
Zip Code
90095
Ferris, Daniel P; Lu, Jie; Gothard, Chris et al. (2011) Synthesis of biomolecule-modified mesoporous silica nanoparticles for targeted hydrophobic drug delivery to cancer cells. Small 7:1816-26
Kovochich, Michael; Espinasse, Benjamin; Auffan, Melanie et al. (2009) Comparative toxicity of C60 aggregates toward mammalian cells: role of tetrahydrofuran (THF) decomposition. Environ Sci Technol 43:6378-84
Nel, Andre E; Mädler, Lutz; Velegol, Darrell et al. (2009) Understanding biophysicochemical interactions at the nano-bio interface. Nat Mater 8:543-57
Araujo, Jesus A; Nel, Andre E (2009) Particulate matter and atherosclerosis: role of particle size, composition and oxidative stress. Part Fibre Toxicol 6:24
Xia, Tian; Kovochich, Michael; Liong, Monty et al. (2009) Polyethyleneimine coating enhances the cellular uptake of mesoporous silica nanoparticles and allows safe delivery of siRNA and DNA constructs. ACS Nano 3:3273-86
Xia, Tian; Li, Ning; Nel, Andre E (2009) Potential health impact of nanoparticles. Annu Rev Public Health 30:137-50
Li, Ning; Wang, Meiying; Bramble, Lori A et al. (2009) The adjuvant effect of ambient particulate matter is closely reflected by the particulate oxidant potential. Environ Health Perspect 117:1116-23
Xia, Tian; Kovochich, Michael; Liong, Monty et al. (2008) Cationic polystyrene nanosphere toxicity depends on cell-specific endocytic and mitochondrial injury pathways. ACS Nano 2:85-96
Li, Ning; Xia, Tian; Nel, Andre E (2008) The role of oxidative stress in ambient particulate matter-induced lung diseases and its implications in the toxicity of engineered nanoparticles. Free Radic Biol Med 44:1689-99
Xia, Tian; Kovochich, Michael; Liong, Monty et al. (2008) Comparison of the mechanism of toxicity of zinc oxide and cerium oxide nanoparticles based on dissolution and oxidative stress properties. ACS Nano 2:2121-34

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