Barrier Function of Brain Microvascular Endothelial Cells is Compromised by Oil Dispersant COREXIT®

Abstract

An outcome of oilspills is the introduction of volatile organic compounds from crude oil and oildispersants into the environment. These compounds can have narcotic andcarcinogenic effects for humans and terrestrial vertebrates. While the grossmorphological, physiological, and toxicological effects of oil‐derived compoundsand oil dispersants are being intensively studied, the more subtle effects onbehavior are poorly understood. While there are many mechanisms by whichtoxicants can affect behavior, the blood‐brain barrier represents an importantdefense in keeping toxicants and other neurologically active substances frompenetrating and disrupting the central nervous system. Consequently, anysubstance that disrupts the integrity of the blood‐brain barrier has thepotential for altering behavior. Severalsuch substances have been detected off‐gassing from oil after a spill, includingthe model polycyclic aromatic hydrocarbon (PAH), benzo[a]pyrene (BaP). Wehypothesized that BaP, and oil dispersant, COREXIT®, will significantly disruptbarrier function of mouse brain microvascular endothelial cells (BMECs) – oneof the primary constituents of the blood‐brain barrier. We cultured monolayersof BMECs in 96‐well plates that were fitted with printed circuits to continuouslymeasure the transendothelial electrical resistance (TEER) of the monolayer usingthe Applied BioPhysics ECIS system. After the cell monolayer reached maximalconfluency, cells were treated with BaP (0, 0.1, 1, 10, 100, 1000, or 10000 nM;n=4/concentration) or COREXIT® (0, 2.5, 5, 10, 20, 40, 80, or 160 ppm;n=4/concentration), and TEER was measured for the next 20 hours. None of the BaP concentrations produced asignificant reduction in TEER. Incontrast, COREXIT® caused a concentration‐dependent decrease in TEER(p<0.05), with a 70% reduction occurring within 5 hours after treatment of160 ppm. We further hypothesized thatcell proliferation, and gene expression of endothelial cell activation marker Icam‐1, and junction protein Cldn5 of BMECs will be significantlymodified by COREXIT®, but not BaP. BMECswere cultured in 96‐ or 24‐ well plates to measure cell proliferation by MTTassay, and gene expression of Icam‐1,and Cldn5 after BaP or COREXIT® treatment at concentrations used previously (n=3/concentration). Interestingly, COREXIT® caused a concentration‐dependent decrease in both Icam‐1 and Cldn5 expression(p<0.05), despite causing an increase in cell proliferation at treatmentrange of 2.5 to 80 ppm (p<0.05), and a sharp reduction at 160 ppm(p<0.05). These data suggest that exposure to COREXIT® concentrations below80 ppm promoted cell proliferation to buffer disruption of junction proteinexpression, and reduction of overall barrier function. BaP had no significanteffect on BMEC proliferation or gene expression. These experiments confirm that oildispersants used to treat oil spills have the potential for producing subtlebehavioral as well as morphological and physiological effects in mammalsthrough interference with the blood‐brain barrier's integrity. In follow‐onstudies, we plan to examine the potential synergistic effect of oil dispersantand PAHs on blood‐brain barrier function and behavior.Support or Funding InformationFunding provided by the Gulf of Mexico Research Initiative, and National Science Foundation to W.W.B., and the U.S. Army to D.H.H.The views expressed in thispresentation are those of the authors and do not reflect the official policy orposition of the Department of the Army, the Department of Defense, or the U.S.Government.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.