1. Introduction & Hypothesis
Effects of the Trichloroethylene Metabolite S-(1,2-Dichlorovinyl)-L-Cysteine on Mitochondrial Function in Human Cytotrophoblasts
Authors: Elana R. Elkin, MPH and Rita Loch-Caruso, PhD
P42 Superfund Research Center
Presented By: Elana Elkin
Background: The PROTECT Center
Figure 6. DCVC induced concentration-dependent changes in mitochondrial oxygen consumption rate (OCR).
The PROTECT Center studies exposure to environmental contamination in Puerto Rico and its contribution to preterm births. Preterm birth is the leading cause of neonatal mortality in the U.S., and is associated with chronic health conditions and developmental disabilities. Puerto Rico preterm birth is one of the highest in the world (as high as 20% in 2008) and faces extensive contamination problems (more than 200 contaminated sites). The overarching goal of PROTECT is to employ an integrated, cross-disciplinary approach to study the fate, transport, exposure, health impact and remediation of contaminants, such as phthalates and chlorinated solvents as both suspect and model agents in the high preterm birth rates. To achieve that goal, PROTECT encompasses five research projects, and 6 cores.
Introduction & Hypothesis A. B.
Trichloroethylene (TCE), an industrial degreaser, is a common environmental contaminant found in more than 800 Environmental Protection Agency-designated Superfunds sites across the United States. Recently classified as a “known human carcinogen,” it has been shown to be a potent renal and hepatic toxicant through its metabolites such as S-(1, 2-dichlorovinyl)-L-cysteine (DCVC). Despite its known toxicity, effects of TCE on the human placenta have only minimally been explored. Placenta, the ephemeral organ that supports and protects growing fetuses during pregnancy, is a likely candidate for toxicity because of its high perfusion rate and ability to metabolize toxicants. This study assessed the effects of DCVC exposure on mitochondrial function in human placental cells.
During the process of placentation, extravillous trophoblasts of fetal origin invade the maternal uterine wall, facilitating the remodeling of tissue and spiral arteries, which become the primary maternal blood supply for the placenta. Altered placental trophoblast function resulting from toxicity can jeopardize placental development potentially leading to adverse pregnancy outcomes such as preeclampsia. Placental trophoblasts have high metabolic activity and energy requirements during maternal uterine invasion and tissue remodeling. Recently, our lab demonstrated that DCVC causes oxidative stress and loss of mitochondrial membrane potential, indicating DCVC-induced mitochondrial toxicity.
Puerto Rico
Low income
Latino population
DCVC induced concentration-dependent decreases in basal respiration (A) and oxidative phosphorylation-linked ATP production (B). In addition, these data may indicate a drop in the availability of biofuel sources within the cell.
> 200
Contaminated Sites 16
Superfund Sites C. D.
Potential Contribution To
Figure 1. Illustrated depiction of placental villi and trophoblast invasion of the uterus [1]. B.
Figure 3. Illustrations of Seahorse XF24 analyzer array. (A) Probes for measuring oxygen and pH of media surrounding intact cells and (B) electron transport targets for mitochondrial complex inhibitors and uncoupler [2].
A..
DCVC decreased maximum respiratory capacity (C) and spare respiratory capacity (D). These data suggest that DCVC may decreases the bioenergetic limit at which the cell can operate, thereby limiting the cells’ ability to respond to stressful conditions requiring large oxygen consumption. F. G.
Basal Respiration: Baseline oxygen consumption
ATP Production: Oxygen consumption linked to aerobic ATP production
Maximum Respiratory Capacity: Maximum amount of oxygen consumed by the cell through cellular respiration
Spare Respiratory Capacity: The difference between maximum respiration and the basal respiration; flexibility of respiration processes
Coupling Efficiency: Proportion of the oxygen consumed during substrate oxidation used to drive ATP phosphorylation
H+ Leak: Permeability of the mitochondrial membrane to protons
Non-mitochondrial Respiration: Oxygen consumed by non-mitochondrial sources
Objective
Heading:
This study assessed the effects of DCVC exposure on mitochondrial function in human placental cells.
Figure 4. Sample oxygen consumption rate (OCR) profile. Illustrated to define measurements and calculated parameters [2].
DCVC decreased coupling efficiency, suggesting changes in electron transport chain substrate oxidation patterns (F). Changes in proton leak were not statistically significant (G).
Materials and Methods
Conclusions
The TCE metabolite DCVC induced concentration-dependent mitochondrial dysfunction in first-trimester placental cells as indicated by multiple key parameters.
These data agree with our previous study showing a DCVC-induced decrease of mitochondrial membrane potential.
Future research will evaluate the significance of DCVC-stimulated mitocondrial dysfunction on overall placental cellular function in the larger context of pregnancy.
Results
Figure 5. DCVC-induced aberrations in overall oxygen consumption profile. DCVC demonstrates a concentration- dependent decrease in OCR responsiveness to the mitochondrial complex V inhibitor oligomycin, indicating a drop in oxygen-linked ATP production. The profile also demonstrates a concentration-dependent decrease in OCR following exposure to the membrane uncoupler FCCP, indicating a drop in the cells’ ability to respond to stressful situations requiring high oxygen utilization to maintain homeostasis.
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Figure 2. HTR-8/Svneo cells are extravillous trophoblasts derived from first trimester human placenta.
References
[1] Robbins, J. R., K. M. Skrzypczynska, V. B. Zeldovich, M. Kapidzic and A. I. Bakardjiev (2010). "Placental syncytiotrophoblast constitutes a major barrier to vertical transmission of Listeria monocytogenes." PLoS Pathog 6(1): e
[2] Seahorse XF Cell Mito Stress Test Kit User Guide, Agilent Technologies.
This poster was supported by Award Number P42ES from the National Institute Of Environmental Health Sciences. The content is solely the responsibility of the authors and does not necessarily represent the official views of the  National Institute Of Environmental Health Sciences or the National Institutes of Health.
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