The Toxicologist - Society of Toxicology

8-oxo-deoxyguanosine (8-oxo-dG), a hallmark biomarker for oxidative stress in biological
systems. We conducted the current study to determine if levels of 8-oxodG
in the urine of smokers were differentiated by race, sex, or the smoking of menthol
cigarettes. Our study of 110 heavy smokers included 56 non-menthol smokers
and 54 menthol smokers whose usual brands had similar yields (~ 10 mg ‘‘tar’’ machine-measured
under the ISO protocol), comprised 63 female & 47 male subjects,
and 28 black & 82 white participants. Individuals were allowed to smoke their
usual brand ad libitum and averaged 31 cigarettes per day. There was no statistically
significant difference in 8-oxo-dG levels between smokers of menthol (median,
96.1 (25th, 75.8; 75th, 141.2) pg/mg creatinine) and smokers of non-menthol cigarettes
(105.1 (73.0, 155.2) pg/mg creatinine, p = 0.25). There was also no difference
between menthol and non-menthol smokers when further segregated by race
or by sex. Levels of urinary 8-oxo-dG were 14% higher among female smokers
(105.6 (79.8, 165.7) pg/mg creatinine) compared to male smokers (92.8 (63.4,
142.6) pg/mg creatinine, p < 0.05), and 22% higher among white smokers (105.6
(81.2, 165.7) pg/mg creatinine) compared to black smokers (86.5 (63.4, 113.6)
pg/mg creatinine, p < 0.05). Correlations between urinary biomarkers of exposure
and levels of 8-oxo-dG demonstrated a modest association with NNAL (r = 0.55),
trans-3’-hydroxycotinine (r = 0.56), and cotinine (r = 0.51). There was no apparent
correlation with urinary nicotine (r = 0.35) or blood COHb (r = 0.15). This study
findings indicate that urinary 8-oxo-dG levels were not differentiated by the smoking
of menthol cigarettes.
1289 IMBALANCED EPITHELIAL ANTI-VIRAL RESPONSES
INDUCED BY CIGARETTE SMOKE (CS).
S. Tao and Y. Chen. Pharmacology and Toxicology, School of Pharmacy, Tucson, AZ.
Historically, bacteria have been considered to be the main infectious cause of the
exacerbation of cigarette smoke (CS) related diseases such as chronic obstructive
pulmonary disease (COPD). However, the wide use of sensitive detection method
(e.g. PCR) has demonstrated that viruses are major contributors in almost 40% of
outpatient COPD exacerbations and an even higher percentage of patients with severe
exacerbations. Human Rhinovirus (RV) has been found to be a major viral
pathogen to induce COPD exacerbations. But the underlying mechanism is not
clear. Since airway epithelium is the primary encounter of CS exposure and also the
main route of RV infection, we used human airway epithelial cell culture (both cell
line and primary cell) as an in vitro model to examine the interaction between CS
exposure and RV infection. Interestingly, pre-exposure to CS synergistically increased
RV-induced pro-inflammatory cytokine production, while severely blocked
the Interferon (IFN) dependent anti-viral defense. The latter effect led to a significant
increase of RV production, which could further increase the inflammation and
exacerbate the symptom of the existing disease as what would happen in the airways
of COPD exacerbation.
1290 NITRITE AND METHEMOGLOBIN FORMATION
UPON NO2 EXPOSURE MAY TRIGGER OXIDANT
STRESS AND CARDIOVASCULAR DYSFUNCTION.
POSSIBLE MECHANISM FOR TRAFFIC-INDUCED
ADVERSE EFFECTS.
C. Monteil 1 , C. Crochemore 1 , V. Keravec 2 , D. Preterre 2 and J. Morin 1 . 1 U644,
INSERM, ROUEN, France and 2 CERTAM, CERTAM, Saint Eienne du Rouvray,
France. Sponsor: R. Forster.
Epidemiological study clearly associate atmospheric pollution and cardiorespiratory
diseases. Diesel engine emissions are clearly designated as an important trigger.
Beside particulate matter, NO2 seems to to be a major candidate for inducing tissular
oxidant damage. The use of oxidation catalyst as a diesel engine emission
after-treatment strategy proved to induce the highest oxidative damage on both in
vitro and in vivo systems during direct aerosol exposure. The observed oxidative
damage downstream oxidation catalyst closely correlates the NO2 concentrations
but failed to correlate particulate matter concentrations. We used CPH as a spin
probe to interact with potential ROS present in combustion emitted aerosols, CP*
was then assayed by electron spin resonance ESR. The occurrence of CP* closely
correlates aerosol NO2 concentrations but failed to correlate particulate matter. We
demonstrate the occurrence of CP* formation during the exposure of cell culture
medium for 60 min to a continuous flow of 5ppm NO2 which was inhibited by the
presence of anti-oxidant agents like GSH, ascorbate, MEG or sodium dithionite.
We also demonstrate the formation of nitrite and nitrate in the culture media exposed
to 5ppm NO2. Nitrite is known to react with hemoglobin to form methemoglobin
we thus exposed human and rat blood for 1 and 3 hours to a continuous
276 SOT 2011 ANNUAL MEETING
flow of NO2 and then assayed for methemoglobin formation. A concentration and
time dependent formation of methemoglobin was clearly evidenced from 3ppm
NO2 in the atmosphere. We suggest that beside the GSH depletion and oxidative
stress known to occur in lung tissue and BAL, gaseous NO2 when interacting with
blood in the alveolar area may produce nitrite and methemoglobin. Both nitrite
and methemoglobin formed upon NO2 exposure may trigger cardiovascular dysfunction
and contribute to the mechanisms of traffic induced adverse effects.
1291 PARTICULATE MATTER-INDUCED LIPID PROFILE
ALTERATIONS IN HUMAN ENDOTHELIAL CELLS.
L. Yu 1 and A. Jeng 2 . 1 Biomedical Sciences Program, Old Dominion University,
Norfolk, VA and 2 Community and Environmental Health, Old Dominion University,
Norfolk, VA.
Epidemiological and animal data have shown that exposure to ambient particulate
matter (PM) lead to enhanced atherosclerosis. PM can induce lipid peroxidation
and form bioactive lipids, which may be involved with the pathogenesis of atherosclerosis.
However, data on assessment of oxidized lipid formation induced by PM
are very limited due to low resolution of mass spectrometry methods. Taking advantage
of available Fourier Transform Ion Cyclotron Resonance Mass
Spectrometer (FTICR-MS) with 12 Tesla at Old Dominion University, this study
aims to assess lipid peroxidation induced by PM at 2.5 μm and how it alters the
lipid profile and oxidizes lipids in human coronary artery endothelial cells. The endothelial
cells were exposed to PM2.5 as a function of two variables: the dose of
PM2.5 and the duration time of exposure. Then, lipid peroxidation in cells was assessed,
and lipids were extracted for lipid species identification. After PM2.5 exposure,
malondialdehyde levels increased and correlated with reactive oxygen species
levels. The analysis of spectrum data from FT-ICR-MS showed changes of cellular
lipid profile in the exposed groups as compared to a control. Van Krevelen diagrams
revealed PM-exposed groups had cluster molecules, defined as lipids according to
the compound classes. Kendrick mass defect analysis was used to differentiate the
exact mass of the functional COO group; the homologous series falling on the same
line suggested oxidation was occurring. In conclusion, PM2.5 caused an oxidation
pathway to form oxidative lipids in cells. This study has advanced the analytical
ability to identify lipids and develop novel data analysis approaches that are applicable
in revealing oxidative lipid formation induced by PM2.5.
1292 HYDROXYL RADICAL FORMATION BY REDOX
CYCLING OF QUINONES IN DIESEL EXHAUST
PARTICLES.
R. G. Udasin 1 , K. C. Fussell 1 , Y. Wang 2 , V. Mishin 3 , D. E. Heck 4 , D. L.
Laskin 1, 3 and J. D. Laskin 1, 2 . 1 Joint Graduate Program in Toxicology, Rutgers
University/UMDNJ, Piscataway, NJ, 2 Environmental & Occupational Medicine,
UMDNJ-RW Johnson Med. Sch, Piscataway, NJ, 3 Pharmacology & Toxicology,
Rutgers University, Piscataway, NJ and 4 Department of Environmental Health
Science, New York Medical College, Valhalla, NY.
Epidemiologic studies have demonstrated a strong association between air pollution
and pulmonary morbidity and mortality. Of particular concern are fine particulate
matter (PM). Diesel exhaust particles (DEP) are a significant source of fine
PM in the atmosphere. Typically containing a carbon core that absorbs many organic
compounds including polycyclic aromatic hydrocarbons, aldehydes and
quinones, DEP are known to stimulate both macrophages and bronchial epithelial
cells to generate reactive oxygen species (ROS). Quinones are of particular interest
because of their ability to redox cycle and generate toxic hydroxyl radicals. In the
present studies, redox cycling of three quinones in DEP [1,2-naphthoquinone (1,2-
NQ), 1,4-naphthoquinone (1,4-NQ), and 9,10-phenanthrenequinone (PAQ)] was
compared in enzyme assays using rat liver microsomes. Hydroxyl radicals were
measured using terephthalate (TPT), a fluorescent hydroxyl radical trap. Quinone
redox cycling was NADPH-dependent and generated both superoxide anion and
hydrogen peroxide. Hydroxyl radicals were only formed in the presence of iron.
PAQ was efficient in generating hydroxyl radicals (Km = 0.37 μM, Vmax = 1.6
nmol 2-OH TPT/min/mg microsomal protein), followed by 1,4-NQ (Km = 0.87
μM, Vmax = 2.4) and 1,2-NQ (Km = 2.7 μM, Vmax = 4.2). Hydroxyl radical formation
was inhibited by diphenyleneiodonium, a flavoenzyme inhibitor, indicating
that cytochrome P450 or cytochrome b5 reductase mediated redox cycling.
Antioxidants such as DMSO, GSH, resveratrol and α-tocopherol blocked hydroxyl
formation. These data indicate that DEP-associated quinones are effective redox cycling
agents. Formation of cytotoxic ROS such as hydroxyl radicals have the potential
to contribute to PM-induced lung injury. Support: AR055073, ES004738,
CA093798, CA132624 and ES05022.