Comparison of the Acute Immunotoxicity of Nonfractionated and Fractionated Oil Sands Process-Affected Water Using Mammalian Macrophages

Abstract

OSPW is a complex mixture of inorganic and organic substances and its principal toxic components have yet to be fully characterized. Previously, we showed in vitro that the oil sands process-affected water (OSPW) organic fraction (OF) caused a concentration-dependent immunotoxicity in mammals. In the present study we further explore the immunotoxicological properties of OSPW in mammals using a series of in vitro bioassays. Specifically, using the RAW 264.7 mouse macrophage cell line we show that whole OSPW containing naphthenic acid (NA) concentrations ranging from 12 to 18 mg/L, significantly inhibited cell proliferation, reduced cell viability, and was directly cytotoxic, whereas the exposure of cells to equivalent doses of the OSPW-OF had no measurable effects. Whole OSPW exposures also caused morphological changes in RAW 264.7 cells, and at sublethal doses (i.e., 10 mg/L) it induced the early expression of the stress genes hmox1 and gadd45. In addition, at NA concentrations of 10 mg/L, whole OSPW but not the OSPW-OF had significant effects on pro-inflammatory cytokine mRNA levels and cytokine protein secretion activities. Finally, whole OSPW also impaired the ability of RAW 264.7 cells to perform phagocytosis. Overall, we demonstrate that exposure to whole OSPW (at NA doses ranging from 10 to 20 mg/L), but not the OSPW-OF caused both cytotoxic and immunomodulatory changes in mouse macrophages. This suggests that the complex mixture of inorganic and organic components found in whole OSPW are acutely toxic at much lower doses than we previously reported for the OSPW-OF (i.e., 50 mg/L) due to unknown additive and/or synergistic interactions that likely occur between the various components present in whole OSPW.

Effect of amino acid composition of elastin‐like polypeptide nanoparticles on nonspecific protein adsorption, macrophage cell viability and phagocytosis

“…RAW 264.7 cells were obtained from American Type Culture Collection (ATCC; RAW 264.7 TIB‐71) and have been extensively characterized in previous studies using molecular and gene expression analysis, functional cell response assays that are specific for RAW 264.7 immune cells, and thoroughly imaged (confocal, SEM, brightfield) to visualize morphological features characteristic of phagocytic RAW 264.7 cells. [ 33–37 ] The cells were grown to confluence at 37°C with 5% CO 2 in culture media consisting of DMEM with Earle's balanced salt solution (Sigma‐Aldrich, Canada) supplemented with 1% 2 mM l ‐glutamine, 1% penicillin/streptomycin and 10% heat‐inactivated FBS. Cells were passed every 36 hours by harvesting cells in a harvest buffer medium (1.5 mM EDTA, 135 mM NaCl, 20 mM HEPES, 5 mM KCl, pH 7.4) at 37 °C with 5% CO 2 for 10 minutes.…”

Overview of Existing Science to Inform Oil Sands Process Water Release: A Technical Workshop Summary

“…Studies involving mammals have been conducted and allow for the potential impacts of OSPW on reclaimed landscapes to be considered (Garcia-Garcia, Pun et al 2011;Garcia-Garcia et al 2012;Fu et al 2017). Additionally, mammalian studies that involve exposure to OSPW focusing on liver and immune responses as indicators of metabolism and excretion have relevance to, and can inform, human health implications (Rogers et al 2002;Garcia-Garcia, Ge et al 2011;Garcia-Garcia et al 2012).…”

A Light Touch: Solar Photocatalysis Detoxifies Oil Sands Process-Affected Waters Prior to Significant Treatment of Naphthenic Acids

“…A number of standard toxicological assays have been developed by Environment & Climate Change Canada for WET testing, of which fish assays are among the most acutely sensitive to OSPW organics (and hence were selected for use herein); ,,− other WET outcomes may be different. While standardized testing has merit for situating results within a broader environmental and toxicological context, toxicity testing beyond these selected organisms (e.g., with native fauna, , cell-line assays) remains important for developing a comprehensive assessment of OSPW toxicity.…”