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Oleic acid exposure of cultured endothelial cells alters lipid mediator production
Citation:
Bass, V. AND M. Madden. Oleic acid exposure of cultured endothelial cells alters lipid mediator production. Society of Toxicology Meeting, New Orleans, LA, March 13 - 17, 2016.
Impact/Purpose:
The project will inform the Agency as to the cardiovascular effects of copollutant exposures with one pollutant being a fatty acid, which is present in many/most combustion sources. Additionally the project aims overlap with other ACE projects including altering dietary fatty acid intake and examination of the effects on cardiac injury induced by PM exposure.
Description:
Diesel, biodiesel, and other combustion sources contain free fatty acid (FFA) components capable of entering the body through particulate inhalation. FFA can also be endogenously released into circulation in response to stress. When in circulation, bioactive FFA may interact with cells lining the blood vessels, potentially inducing endothelial dysfunction. To examine the effects of FFA on vascular cells, human umbilical vein endothelial cells (HUVEC) were exposed to oleic acid (OA) with one of two vehicles, either bovine serum albumin (OA-BSA) or ethanol (OA-EtOH). Dose-dependent cytotoxicity was noted at 4hr with an increase in LDH activity at 250µM OA-BSA (25% above controls), increasing to 50% in HUVEC exposed to 1mM OA-BSA for 48hr. These observations were confirmed through dose-response testing of viability (MTT assay), which yielded a 20% reduction in viability relative to controls at 1mM OA-BSA. These data demonstrate that the threshold for direct OA-induced cytotoxicity is approximately 100µM OA-BSA at 24hr. HUVEC were also exposed to methylated-OA at similar doses, which yielded no increase in LDH release, suggesting that the carboxyl group on OA is necessary to induce cytotoxic effects. 14C-OA cellular uptake experiments showed that 80% of labeled OA-EtOH became associated with HUVEC, versus only 8% of OA-BSA at 24hr. Analysis of soluble mediator release from HUVEC showed a dose-dependent increase in prostaglandin F2α, a lipid involved in control of vascular tone, at 24 hours (85% above controls) after OA-BSA exposure. RT-PCR analysis revealed increased endothelin-1 mRNA in OA-BSA exposed HUVEC. Together, these data demonstrate that circulating FFA may be capable of inducing cytotoxic effects and altering expression of mediators of vascular function. [This is an abstract of a proposed presentation and may not reflect official US EPA policy.]