The Toxicologist - Society of Toxicology

2330 THE ROLE OF TRANSFORMING GROWTH FACTOR
BETA 1 (TGF-β1) IN TOBACCO-SMOKE-INDUCED
LUNG INJURIES.
L. L. Hoang and K. E. Pinkerton. Center for Health and the Environment,
University of California, Davis, Davis, CA.
Rationale: Chronic obstructive pulmonary disease (COPD) is the fourth leading
cause of death in the United States with 80-90% of all COPD cases attributed to
smoking. Clinical studies have shown strong correlations between the progression
of COPD and small airway remodeling indicated by increased small airway wall
thickness, airway inflammation, mucus hypersecretion, and increased airway
smooth muscle mass. However, the mechanism of small airway remodeling in
COPD remains elusive. Previous clinical research demonstrated increased TGF-β1
expression in the lungs of COPD patients. TGF-β1 could be critical to small airway
remodeling in COPD due to its ability to regulate both immune cells and airway
structural cells. Therefore, we used TGF-β1+/- mice exposed to tobacco smoke to
study the functions of TGF-β1 in tobacco smoke induced lung injury. Methods:
TGF-β1+/- mice were exposed to tobacco smoke at 150 mg/m3 for 6 hours/day, 5
days/week for one month. Lungs were lavaged for analysis of cell viability, number
and cell differential. Tracheas and lung lobes were frozen for qRT-PCR experiments.
Results: Compared to wild type mice, TGF-β1+/- mice exhibited an increase
in inflammatory cells recovered in the bronchoalveolar lavage fluid following
smoke exposure. TGF-β1+/- mice exposed to tobacco smoke also showed a reduction
in tracheal Muc5b mRNA expression. Smooth muscle alpha actin mRNA expression
was also found to be elevated in the lungs of TGF-β1+/- mice following
smoke exposure. Conclusions: We conclude TGF-β1 may protect the lungs from
tobacco smoke induced pulmonary inflammation. TGF-β1 may also play a critical
role to regulate mucus production and decrease airway smooth muscle hypertrophy
during tobacco smoke exposure. Funded by: NIEHS (ES 011634 and ES013932)
and TRDRP (18XT-0154)
2331 RESPIRATORY AND SYSTEMIC RESPONSES TO URBAN
SUMMER AND WINTER SUB-MICRON FINE AND
ULTRAFINE PARTICULATE MATTER.
L. E. Plummer 1 , C. M. Carosino 1 , K. J. Bein 2 , A. S. Wexler 2 and K. E.
Pinkerton 1 . 1 Center for Health and the Environment, University of California, Davis,
CA and 2 Civil and Environmental Engineering, University of California, Davis, CA.
Understanding seasonal impacts on adverse respiratory and systemic health effects
can lead to more effective targeting of sources for improved control of particulate
matter (PM) pollution, a concern for California’s San Joaquin Valley (SJV).
Toxicological evaluation of PM is critical in providing biological relevance for observed
effects. Therefore, we tested the pro-inflammatory potential of SJV summer
and winter PM sub-micron fine (SMF) and ultrafine (UF) from urban Fresno, CA
in the lungs and blood of healthy male Balb/C mice. Inflammatory cell profile and
cytotoxicity were measured 24 hours after intratracheal instillation of 25, 50 and
100 μg of PM/mouse. PM size distributions and oxidative potential were characterized
using dynamic light scattering (DLS) and the cell-free dithiothreitol (DTT)
assay, respectively. For all doses and both size-fractions, winter PM induced significantly
greater acute pulmonary inflammation than equivalent doses of summer PM
and was characterized by a robust, dose-dependent total leukocyte, neutrophil and
lymphocyte influx. On an equal mass basis, winter SMF PM was more pro-inflammatory
than winter UF PM however this difference was not statistically significant.
Dose-dependent increases in circulating inflammatory cells and hematologic
changes did not attain statistical significance. Particle measurements confirmed efficient
dispersion and higher oxidative potential of winter versus summer PM for
both size fractions. Pro-inflammatory potential of Fresno PM was significantly influenced
by size and season. The relative toxicity within the lung was ranked: winter
SMF > winter UF > summer SMF > summer UF. The potency of winter PM
may be associated with observed DTT activity of winter SMF and UF PM. These
studies are the initial results for source-oriented particle sampling and toxicity testing
designed to elucidate key source contributors to PM toxicity. Funded by
CARB/EPRI.
2332 PARTICLE UPTAKE OF GASEOUS AIR TOXICS
MODIFIES OBSERVED TOXICITY OF PM.
S. M. Ebersviller1 , K. Lichtveld1 , J. Zavala1 , Y. Lin1 , K. G. Sexton1 , I. Jaspers1, 2
and H. Jeffries1 . 1Environment Sciences . and Engineering, UNC-CH, Chapel Hill,
NC and 2CEMALB, UNC-CH, Chapel Hill, NC.
The National Research Council has called for efforts toward determining whether
‘effect modification’ occurs between particulate matter (PM) and gases that surround
it in the environment. Researchers have long known that gases and particles
interact via dynamic processes in the atmosphere. What has been unclear to this
point is if these interactions affect the actual toxicity of each phase. To investigate
these processes, a series of experiments was conducted in an outdoor smog chamber
capable of mimicking the ambient environment. In vitro cell cultures were exposed
to the gas and particle phases of air mixtures using gas and particle exposure systems
coupled directly to the chamber, thereby allowing exposures to occur without sampling
artifacts. Mineral oil aerosol (MOA) acted as a non-toxic analog to ambient
PM, as it possesses representative complexity in composition but lacks any inherent
toxicity that may interfere with observations. A mixture of 55 compounds was injected
into the chamber to represent a typical urban atmosphere. Exposures to the
fresh chamber contents were performed both with and without MOA present.
Chamber contents were allowed to react in natural sunlight for one day and exposures
were repeated, again with and without MOA. As observed in previous work,
the fresh mixture induced no response from exposed cells with either in vitro
method, while there was a dramatic increase in response from cells exposed to the
aged mixture using the gas-only system. For the system in which there was no PM
present, there was no response from the cells exposed with the particle-only
method. When MOA was added to the chamber after sundown, however, there was
more than 6X the inflammatory response than was observed for any controls or the
fresh exposure. As the MOA was added after sunset, the only source this increase in
toxicity was the uptake of toxic species from the air surrounding the aerosol. These
results together provide clear proof that ‘effect modification’ can, and is likely to,
occur in the ambient environment.
2333 CONTRIBUTIONS OF TRPV1 AND TRPM8 TO LUNG
INJURY BY COAL FLY ASH.
C. A. Reilly, C. E. Deering-Rice, M. E. Johansen, J. K. Roberts, E. G. Romero,
J. M. Veranth and G. S. Yost. Pharmacology and Toxicology, University of Utah, Salt
Lake City, UT.
Acute and long-term heath deficits are correlated with exposure to environmental
particulate pollutants (PM). However, the molecular sensors that detect, differentiate,
and respond to PM are often unknown. TRPV1 has been implicated as a sensor
of PM and activation of TRPV1 has been correlated with inflammation, cell
death, and altered cardiopulmonary function. This research investigated TRPV1
activation using a series of prototype PM, established a role for TRPV1 in pulmonary
injury following instillation of PM into lungs of mice, and identified
mechanisms of TRPV1 activation. A screen of TRPV1 activation by 8 prototype
PM identified a coal fly ash PM (CFAm), silica, and diesel exhaust PM (DEP) as
agonists. CFAm did not activate TRPA1, V3, or V4, but activated TRPM8. Like
capsaicin, CFAm induced the expression of CXCL-1/KC, CXCL-2/MIP-2α and
IL-6 in distal airways, and pro-apoptotic GADD153 in alveoli, consistent with
lung injury in C57Bl/6 mice. CFAm activated cultured mouse DRG neurons and
induced the expression of IL-6, IL-8, and GADD153 in primary human bronchial
epithelial (NHBE) cells, all of which were attenuated by the TRPV1 antagonist
LJO-328. Accordingly, CFAm-induced lung injury in TRPV1-/- mice was reduced.
Calcium flux in TRPV1 over-expressing human bronchial epithelial cells by CFAm
was inhibited by co-treatment by LJO-328 and by inhibition of cell surface TRPV1
using EGTA and ruthenium red. Responses were also exacerbated by enriching
TRPV1 at the cell surface. TRPV1 activation was attributable to the solid core fraction
of CFAm and occurred through an interaction with residues adjacent to the
pore-loop segment of TRPV1. These data show an additive role for sensory nerve
and non-neuronal TRPV1 in mediating lung injury by a model PM and reveal a
novel mechanism of activation involving PM contact with cell surface residues that
may also occur for other PM that activate TRPV1. Additionally, TRPM8 may also
contribute to lung injury by this PM. Support: ES017431 and HL069813.
2334 ACTIVATION OF HUMAN TRPA1 BY DIESEL EXHAUST
PARTICLES (DEP): ASSOCIATION WITH LUNG INJURY.
C. Deering-Rice, E. G. Romero, J. M. Veranth, G. S. Yost and C. A. Reilly.
Pharmacology/Toxicology, University of Utah, Salt Lake City, UT.
Inhalation exposure to environmental particulate air pollutants (PM) is correlated
with a number of adverse health effects in humans. However, the molecular “sensors”
that detect, differentiate, and initiate deleterious responses to PM that likely
culminate as compromised health are not known. TRPV1 and TRPA1 orchestrate
responses to a number of prototype respiratory toxicants including capsaicin,
acrolein, and crotonaldehyde. The hypothesis of this study was that TRPA1, and
not TRPV1, would be activated by specific forms of environmental PM in vitro
and that activation in vivo would result in lung injury. A screen of 6 prototype PM
revealed that diesel exhaust PM (DEP) activated TRPA1 and that bioactivity was
retained in ethanol extracts. Ethanol extracts of DEP failed to activate TRPM8, V1,
V3 and V4. The extract induced calcium flux in isolated mouse DRG neurons sensitive
to the prototype TRPA1 agonist AITC and were abolished by co-treatment
SOT 2011 ANNUAL MEETING 501