The Toxicologist - Society of Toxicology

821 KIDNEY INJURY MOLECULE-2 GENE DEFICIENT
MICE ARE MORE SUSCEPTIBLE TO CISPLATIN
INDUCED KIDNEY TOXICITY.
A. Krishnamoorthy, E. O’Leary, J. V. Bonventre and V. S. Vaidya. Medicine, Renal
Division, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA.
Kidney injury molecule-2 (Kim-2) or T cell, Ig domain, mucin domain (Tim-2)
belongs to the receptor family of cell surface molecules expressed on kidney, liver
and T cells. Previous studies have revealed that Kim-2-deficient mice (Kim-2 -/- ) are
more susceptible to Th2 mediated immune response. Here we investigated the phenotypic
response of Kim-2 -/- mice to cisplatin-induced inflammation, apoptosis
and mitochondrial damage in the kidney. Male Balb C wild type (Kim-2 +/+ ) and
knockout (Kim-2 -/- ) mice (25-29 g) were administered with 20 mg/kg cisplatin ip
and were sacrificed at 0, 24, 48 and 72 hours (n=4/group/time point). A lethality
study (n=10) suggested that a 20 % lethal dose of cisplatin (20 mg/kg) in wild type
mice resulted in 70 % mortality of Kim-2-/- mice after 72 h. The Kim-2 -/- mice
showed ~ 2-fold higher injury as estimated by blood urea nitrogen and serum creatinine
at 48 h that further escalated at 72 h as compared to Kim-2 +/+ . Histologically,
the outer stripe of outer medulla showed more pronounced apoptosis and necrosis
in the proximal tubules in the Kim-2 -/- as compared to Kim-2 +/+ . A significant increase
in the number of apoptotic cells (TUNEL staining) was observed by 48 h
further escalating by 72 h in the Kim-2 -/- mice as compared to Kim-2 +/+ mice. The
kidney tubular cell proliferation (Ki67 staining) in both groups decreased at 24 h
and peaked at 72 h with no difference amongst the two groups. Further analysis of
genes involved in inflammation and apoptosis revealed early expression of interleukin
1 β (IL1β) by 48 h and ~ 5 fold upregulation of transforming growth factor
β (TGFβ) by 72 h in the Kim-2 -/- mice as compared to wild type. In conclusion the
increased expression of the proinflammatory and proapoptotic genes IL1β, TGFβ,
higher number of apoptotic cells and pronounced increase in injury and mortality
of the Kim-2 deficient mice suggests a protective role of Kim-2 in cisplatin induced
nephrotoxicity.
822 COMPARATIVE NEPHROTOXICITY OF LOW-
OSMOLAR AND ISO-OSMOLAR IODINATED
CONTRAST AGENTS.
L. A. Gardiner 1 , R. C. Burghardt 2 and A. R. Parrish 1 . 1 Systems Biology and
Translational Medicine, Texas A&M Health Science Center, College Station, TX and
2
Veterinary Integrated Biosciences, Texas A&M Health Science Center, College
Station, TX.
Contrast-induced nephropathy (CIN) is the third leading cause of hospital-acquired
renal failure, responsible for 11% of cases. CIN is associated with prolonged
hospitalization and the mortality rate of CIN may be as high as 6-35%. While the
overall incidence of CIN is roughly 3%, it may approach 50% in patients with
multiple risk factors, including CKD, diabetes, and advanced age. Given the clinical
impact of CIN, a number of strategies to reduce the incidence and severity have
been investigated that have reduced the rate of CIN. A major factor has been the
development of contrast medium with reduced nephrotoxicity. Nonionic low-osmolar
agents (LOCM) have fewer renal effects than high-osmolar contrast medium
(HOCM). The generation of iso-osmolar contrast agents (IOCM) was postulated
to be another important step to reduced nephrotoxicity. In the current study, immortalized
mouse (TKPTS) or rat (NRK-52E) proximal tubular epithelial cell lines
were challenged with iohexol, a LOCM or iodixanol, an IOCM. Cells were exposed
to equal iodine concentrations, 25-100 mgI/ml for 3-24 hr. Both iohexol and
iodixanol induced loss of significant loss of viability in a dose-dependent manner
following challenge in both cell lines at all timepoints; at 6 hr the percent viability
for 50, 75 and 100 mgI/ml was 82, 56 and 43 for iohexol and 49, 41, and 32 for
iodixanol in TKPTS cells; similar results were seen at 12 and 24 hr and in NRK
cells. Interestingly, a trend toward increased nephrotoxicity was seen with iodixanol,
the iso-osmolar agent, despite the fact that hyperosmolarity alone (mannitol)
was also associated with loss of viability. These results are in agreement with the
emerging clinical studies suggesting that IOCM may not reduce CIN as compared
to LOCM agents.
823 EVALUATION OF CADMIUM EXPOSURE AND KIDNEY
FUNCTION IN OCCUPATIONALLY NON-EXPOSED
POPULATION.
J. Park, M. Huang, B. Choi, D. Kim, N. Kim and H. Bae. Preventive Medicine,
Chung-Ang University, Seoul, Republic of Korea.
Cadmium (Cd) is a non-essential toxic metal which is widely distributed in the environment.
General population are exposed to the low level Cd chronically and the
kidney is the most sensitive organ to the Cd toxicity. This study was performed to
estimate the level of Cd exposure and affecting factors. Furthermore, we evaluated
the kidney function and oxidative stress biomarkers in the study population. The
study subjects, 643 adults (239 males and 404 females) were interviewed for demographic
characteristics, lifestyles and diets during the last 24 hours. We estimated
daily Cd intake by diet in study subjects who had not been occupationally exposed
to Cd. Whole blood and spot urine samples were collected. We analyzed the concentrations
of Cd in whole blood and urine, kidney function indices (β2-MG,
NAG, MT) and oxidative stress indices (MDA, 8-OHdG). The daily Cd intake
from diet was 7.11 μg/day, the mean concentration of Cd was 1.21 μg/L in blood
and 0.98 μg/L, 0.95 μg/g creatinine in urine. Blood Cd was affected by age, sex,
smoking and dietary Cd intakes. Urinary Cd was affected by age, sex and blood Cd.
The level of MT, NAG activity, MDA and 8-OHdG in urine was positively correlated
with Cd in urine, respectively, while not with blood Cd. The NAG was the
most sensitive to the environmental Cd exposure, which was affected by age, hypertension
and diabetes. However, urinary MT was responded to the urinary Cd only.
These findings suggest that MT might be more specific than NAG to Cd of chronic
and low level exposure. In summary, the human exposure to Cd, chronic and low
level, is affected by environmental and genetic factors, which might eventually
cause to tubular damage in the kidney through the oxidative stress mechanism.
824 THE COMPARISON OF GLOBAL GENE EXPRESSION
IN ACUTE AND CHRONIC CADMIUM EXPOSURE IN
CULTURES OF HUMAN PROXIMAL TUBULE CELLS.
S. H. Garrett, S. Somji, M. Sens and D. A. Sens. Pathology, University of North
Dakota, Grand Forks, ND.
Exposure to the heavy metal cadmium is known to have detrimental effects on the
kidney with acute poisoning causing proximal tubule necrosis. It is gradually being
accepted that even low levels of cadmium exposure may have significant renal toxicological
consequences for many individuals in the general population. Mortal cultures
of human proximal tubule cells have been an excellent in vitro model to study
the toxic effects of this metal and can be used as a model for long-term chronic
studies. In this study, this cell culture system was utilized to study global gene expression
differences during the commonly employed short term exposure (24 h)
and a 13 day long-term exposure. Three doses of cadmium ranging from non-toxic
to sub-lethal concentrations for the 24 h (9, 27, and 45 μM) and the 13 day longterm
exposure (4.5, 9, and 27 μM) were used to model acute and chronic cadmium
exposure respectively. Total RNA was purified from exposed cultures and subjected
to global gene expression analysis using the Affymetrix 133 Plus 2.0 array. There
were a total of 1,421 differentially expressed genes specific to acute exposure, 536
specific to chronic exposure, and 387 differentially expressed genes common to
both exposure conditions. Acute cadmium exposure elicited many genes in the
stress response such as the heat shock group, proliferative genes, and many genes associated
with cell cycle, apoptosis, and cell cycle check points. The majority of these
genes did not remain differentially expressed at the later 13 day exposure time.
Many of the differentially expressed genes specific to chronic cadmium exposure
were found to be members of a wide range of developmental pathways from neuronal
and skeletal development to differentiation pathways. The results of these
studies show a fundamental difference in the global gene expression pattern despite
the fact that there was sub-lethal toxicity during both exposure conditions.
825 REGULATION OF BISPHENOL A-INDUCED
APOPTOSIS IN HUMAN EMBRYONIC KIDNEY CELLS.
H. Kim 1 , S. Yang 2 , M. P. Shakajian 1 , A. M. Vetrano 2 , M. T. Lalloo 1 , J. D.
Laskin 2 and D. E. Heck 1 . 1 Environmental Health Science, New York Medical
College, Valhalla, NY and 2 Environmental and Occupational Medicine, UMDNJ-
RW Johnson Medical School, Piscataway, NJ.
Bisphenol A (BPA) is an environmental contaminant and putative endocrine disruptor.
Although emerging evidence indicates that exposure to BPA modulates
human endocrine responses, little is understood about the mechanisms underlying
these effects. Our laboratory has been studying cellular responses to BPA. Using
human embryonic HEK293 kidney cells we found that BPA (1-30 microM) induces
apoptosis. Expression of transforming growth factor (TGF) beta, an inhibitor
of kidney cell apoptosis, was also diminished. Previous reports indicate that peroxisome
proliferator-activated receptors (PPAR) regulate cellular responses including
apoptosis and glucose metabolism in individuals with metabolic disorders such as
progressive kidney disease. BPA treatment increased expression of PPARbeta
mRNA three-fold; mRNA levels remained elevated for 48 hr. The activity of PPARs
requires intracellular calcium. To examine potential crosstalk between calcium signaling
and PPAR expression following BPA exposure, we established a stable
human embryonic kidney cell line over expressing a ligand-sensitive calcium-permeable
membrane channel (HEK/TRPV1). Both wild type and HEK/TRPV1 cells
SOT 2010 ANNUAL MEETING 175