The Toxicologist - Society of Toxicology

(INH) BS causes more diffuse fibrosis in the lung. Similar to other inflammatory
models (i.e. LPS), INH administration has demonstrated a more distributed pattern
of injury which may closely mimic the human condition. Both models cause
7-10 days of pneumonia-like symptoms that resolve through 14-35 days for the
onset of PF. In this study, we compared the time-course of cellular mediators
(PMN, collagen, IL1beta, MCP-1, TNFalpha, IL4, IL6, IL10, GROKC, RANTES
and IFNgamma) associated with the manifestation of PF in male, F344 rats.
Animals were examined for in-life clinical signs, gross and microscopic pathology,
and changes in cellular mediators at the following endpoints: 5, 7, 10, 14, 21, 28
and 35 days post BS administration. Rats received 3.5-4.0 mg/kg BS on Day 0 and
were observed through 35 days. In these rat models, PMN, MCP1, IL1beta, IL6,
GROKC, and soluble collagen upregulation (or release) trends were similar between
models. By Day 21 inflammation as measured by PMN, MCP1, IL1beta,
GROKC, and IL6 returned to baseline levels. TNFalpha was consistently greater
than baseline through 14 days and then spiked again at 35 days. In parallel to the
inflammatory marks, IL10, IL4, and RANTES were suppressed compared to baseline
levels throughout the disease progression. Fibrotic lesions were grossly observed
beginning at 14 days – data supported by increases in lung collagen. Soluble collagen
was 2-3X baseline beginning at 5 days and stayed elevated through 35 days post
BS administration. Additional endpoints of interest under evaluation include
αSMA, CTGF, MMP7, LDH, and TGFbeta.
541 THE PATHOPHYSIOLOGY OF PROGRESSIVE
EXPOSURE TO TOBACCO SMOKE IN A RODENT
MODEL OF CHRONIC OBSTRUCTIVE PULMONARY
DISEASE (COPD).
L. Wang 1 , S. Bolton 2 and K. E. Pinkerton 1 . 1 Center for Health and the
Environment, University of California, Davis, Davis, CA and 2 Safety Assessment,
AstraZeneca R&D, Loughborough, United Kingdom.
Background: COPD is a leading cause of morbidity and mortality worldwide, however,
we are still far from understanding the complexity and progressive development
of this devastating disease. Objectives: To understand the interactive roles of
pulmonary inflammation, lung physiology and lung tissue remodeling in disease
progression in a rat model of COPD. Methods: Spontaneous hypertensive rats were
exposed to tobacco smoke (TS) (90 mg/m3) or filtered air (FA) for up to 12 weeks.
Timepoints of 4, 6, 8, 10 and 12 weeks for necropsy were chosen to define the
pathophysiological changes in the lung. Results: Bronchoalveolar lavage (BAL), cell
differential, histopathology and lung function tests were performed. Rats exposed
to TS demonstrated an enhanced BAL, airway and alveolar inflammatory responses
reflected by significant increases in macrophage, neutrophil and lymphocyte number
as well as inflammatory cytokines compared to FA at 4, 6, 8, 10 and 12 weeks.
The degree of inflammation increased temporally and peaked between week 6 and
week 8. Airway obstruction was noted by a significant elevation in central airway
resistance, tissue damping and a reduction in total respiratory compliance due to
TS exposure. Central airway resistance demonstrated a decrease at 4 weeks, an increase
at 8 weeks, peaking at 10 weeks and remaining elevated at 12 weeks.
Conclusions: These findings suggest a persistent, but dynamic airway inflammatory
response and airway obstruction in the rat model of COPD. Airway inflammation
alone can not explain the variance in physiological lung function impairment observed
in the TS rats, implying tissue repair and airway remodeling may also contribute
to the airflow limitation. This rat model of COPD could address critical
questions in the mechanistic progression of inflammation and tissue repair in
COPD, which could have implications for future therapy and new drugs. Funded
by AstraZeneca and California TRDRP
542 USE OF MOUSE MODEL AS AN EARLY SCREENING
TOOL FOR PDE4 INHIBITOR-INDUCED
GASTROINTESTINAL TOXICITY.
C. Chen, H. Sexton, K. Jarnagin, X. Fan, W. Bu, A. Wu, Y. Freund and S.
Chanda. Toxicology, Anacor Pharmaceuticals, Palo Alto, CA.
To allow rapid assessment of PDE4 inhibitors-related gastrointestinal (GI) toxicity,
an early in vivo screening model was developed in mice or rats. PDE4 inhibitors
have been reported to cause toxicities in various animal species including dogs, rats,
minipigs, and ferrets. However, limited toxicity studies have been conducted in
mice. Animals were dosed with candidate compounds for 5 consecutive days.
Toxicity evaluation included clinical observation, body weight, gross observation/GI
measurement at necropsy, hematology and fibrinogen analyses. In the
mouse, stomach enlargement was the primary GI finding, which correlated with
fibrinogen elevation. In the rat, GI effects were most severe in the jejunum and
ileum and the GI dilation was highly correlated with increases in neutrophils, white
blood cells and fibrinogen. In these two screening models, results revealed that rat
NOAEL for GI toxicity was 1/2 or 1/3 of that observed in mice treated with the
116 SOT 2011 ANNUAL MEETING
same test compound. The mouse model is considered to be a useful early screening
tool based on the following advantages: 1) milligram quantities of test article are
needed, 2) stomach enlargement and fibrinogen elevation are considered as the primary
indictors for PDE4-related GI toxicity. This mouse model was used to investigate
whether the PDE4 inhibitor-induced GI toxicity was associated with local or
systemic exposure. Mice were dosed once daily for 5 days either via subcutaneous
(sc) injection or oral gavage. Results indicated that the stomach enlargement was
not significantly reduced via sc injection compared to oral dosing, and the systemic
exposure of test compound was comparable between oral and sc dosing routes. The
results suggested that the PDE4-induced GI toxicity is correlated with systemic exposure
and compound affinity. In conclusion, the mouse toxicity screening model
is considered as a useful in vivo tool for the screening PDE4 inhibitors at an early
stage of drug development and was successfully used to evaluate GI toxicity of selected
PDE4 inhibitors.
543 EFFICACY OF PHARMACEUTICAL DRUG COCKTAILS
FOR TREATING CHLORINE VAPOR INDUCED
CUTANEOUS LESIONS.
J. Rhone 1 , J. L. Plahovinsak 1 , E. M. Benson 1 , R. C. Hamilton 1 , F. M. Reid 1 , J.
F. Dillman 2 and J. S. Graham 2 . 1 Biomedical Research Center, Battelle, Columbus,
OH and 2 U.S. Army Medical Research Institute of Chemical Defense, Aberdeen, MD.
Chlorine is an industrial chemical that potentially causes cutaneous burns. The unforeseen
exposure to highly hazardous toxic industrial chemicals has presented the
need to develop animal models for evaluating promising therapeutic compounds
against these chemicals. Battelle’s Biomedical Research Center and the U.S. Army
Medical Research Institute of Chemical Defense have aligned research efforts for efficacy
testing of FDA-approved candidate drugs to promote healing in cutaneous
chlorine vapor (CLV) injuries. A CLV exposure system was previously fabricated
and characterized to induce superficial dermal (SD) lesion sites on the ventral abdomen
of Yorkshire-cross weanling pigs. Sites were exposed to undiluted chlorine
vapor (2.9 g/L) for thirty minutes following the application of a simulated sweat
soaked filter paper. This model was used to assess the efficacy of topical anti-inflammatory
compounds: diclofenac sodium and clobetasol propionate with two
anti-cytokine drugs post-exposure. A third treatment group received topical treatments
only. Lesion assessments were conducted on Study Day 0 (infrared imagery
only), and Study Days 2, 3, and 7 to include digital photographs, wound size measurements,
modified Draize scoring, and non-invasive bioengineering methods (reflectance
colorimetry and infrared imagery). Histopathologic evaluations were performed
for wound healing parameters (re-epithelialization, dermal necrosis, and
fibroplasia) on Study Day 7. The administration of Enbrel and Kineret without
topical anti-inflammatories resulted in reduced lesion size, lower mean modified
Draize scores, and reduced erythema on Study Days 2 and 3. Complete re-epithelialization
was observed in the no treatment sites suggesting that CLV induced SD
lesions may heal without treatment by day 7 post-exposure.
544 EFFICACY OF PHARMACEUTICAL DRUG COCKTAILS
FOR AMELIORATION OF CUTANEOUS SULFUR
MUSTARD INJURIES.
F. M. Reid 1 , J. L. Plahovinsak 1 , M. D. Etheridge 1 , J. Rhone 1 , J. F. Dillman 2 and
J. S. Graham 2 . 1 Biomedical Research Center, Battelle, Columbus, OH and 2 U.S.
Army Medical Research Institute of Chemical Defense, Aberdeen, MD.
The vesicant agent, sulfur mustard [bis(2-chloroethyl)sulfide; SM], remains a threat
to warfighters and civilians worldwide via acts of war and terrorism. Battelle’s
Biomedical Research Center (BBRC), and the U.S. Army Medical Research
Institute of Chemical Defense (USAMRICD) have aligned research efforts for efficacy
testing of candidate drugs to promote wound healing of injuries induced by
SM. Recent work has focused on topical anti-inflammatory compounds: diclofenac
sodium and clobetasol propionate. Using an established SM dermal weanling swine
model, this study evaluated the efficacy of FDA-approved drugs in combination
with topical anti-inflammatory compounds for wound healing in superficial and
deep dermal cutaneous injuries. Two different anti-cytokine drugs were administered
to animals post- exposure in combination with the topical anti-inflammatory
compounds. A third treatment group received the topical compounds only.
Treatment was initiated at 2 hours post exposure. Lesion assessments were conducted
on Study Days 0 (infrared imagery only), 2, 3, and 7. Assessments included
digital photographs, wound size measurements, modified Draize scoring, reflectance
colorimetry, and infrared imagery (day 0 only). Histopathologic evaluations
were performed for wound healing parameters (re-epithelialization, dermal
necrosis, and fibroplasia) on Study Day 7. The administration of both Enbrel and
Thalidomide showed promise in healing HD-induced lesions particularly when
used with both topical anti-inflammatory drugs. This was confirmed histopathologically
by decreased necrosis and increased re-epithelialization. Follow on efforts
will examine additional FDA-approved drugs in combination with topical anti-inflammatory
drugs as determined from the canonical pathway analysis.