Immunotoxic effects ofin vitroexposure of dolphin lymphocytes to Louisiana sweet crude oil and Corexit™

Abstract

The Deepwater Horizon oil spill was one of the worst environmental disasters on record in the United States. Response efforts to reduce the magnitude of the oil slick included the use of thousands of gallons of the chemical dispersant Corexit™ in surface and deep-water environments. The immunotoxicity of Louisiana sweet crude oil and the chemical dispersant Corexit was examined using lymphocyte proliferation (LP) and natural killer cell (NK) assays as measures of impact on the adaptive (LP) and innate (NK) immune response in bottlenose dolphins. Study results show that both high-energy media-accommodated fractions (MAF) and chemically enhanced MAF (CEMAF) mixtures modulate immune function. Following exposure to Louisiana sweet crude, both B- and T-cell proliferation of white blood cells was increased for all exposure concentrations, compared to control; however, this increase was only significant for the 50% and 100% treatments. In contrast, exposure of white blood cells to the CEMAF mixture significantly decreased both T- and B-cell proliferation in the 25%, 50% and 100% treatments. NK cell activity was enhanced significantly by CEMAF mixtures for the 50% and 100% treatments. The immunosuppression of LP at environmentally relevant concentrations of oil and dispersant suggests that marine mammals may be unable to mount an adequate defense against xenobiotic threats following exposure to oil and dispersant, leaving them more susceptible to disease. In contrast, NK cell activity was significantly enhanced, which may increase an organism's tumor or viral surveillance ability by mounting an enhanced immune response. Copyright © 2016 John Wiley & Sons, Ltd.

Bottlenose dolphins (Tursiops truncatus) do also cast neutrophil extracellular traps against the apicomplexan parasite Neospora caninum

“…Investigations on the dolphin adaptive immune system are quite abundant in literature ( Romano et al., 1992 , De Guise et al., 2002 , Mancia et al., 2007 , Beineke et al., 2010 , Sitt et al., 2010 , Zafra et al., 2015 , White et al., 2017 ). Conversely, investigations on the cetacean innate immune system are less commonly found ( Kato and Perrin, 2009 , Schwacke et al., 2010 , Keogh et al., 2011 ) despite the fact that PMN are at the forefront of defense against infection ( Brinkmann and Zychlinsky, 2012 , Silva et al., 2016 ), resolution of inflammation and wound healing ( Rodríguez-Espinosa et al., 2015 ).…”

Review of petroleum toxicity and identifying common endpoints for future research on diluted bitumen toxicity in marine mammals

“…2. Cetaceans experience immune responses (De Guise et al 2017;White et al 2017) and DNA damage (Carvan et al 1995). Of the cetaceans, petroleum exposure in bottlenose dolphins was linked to lung diseases, bacterial pneumonia, adrenal dysfunction, impaired stress response, lethargy, reduced reproductive success, and mortality (Schwacke et al 2014;Lane et al 2015;Venn-Watson et al 2015a;Kellar et al 2017;Smith et al 2017;Wilkin et al 2017).…”

“…Additionally, chronic ingestion of fuel oil elicited multiple immune responses in American mink including elevation of various white blood cells, a significant increase in the absolute numbers of specific peripheral blood lymphocyte subsets, and increases in expression of both functionally significant cell surface proteins and mitogen-induced mononuclear cell proliferative responses (Schwartz et al 2004b). Modulation of immune function also occurred in bottlenose dolphin lymphocytes following in vitro exposure to environmentally relevant concentrations of Louisiana sweet crude oil (1 liter/ 1 gram media/oil) causing both B-and T-cell proliferation of white blood cells to increase (White et al 2017). Health assessments on bottlenose dolphins from DWH oil contaminated regions likewise revealed an increase in B and T lymphocyte proliferation as compared to conspecifics from unoiled regions (De Guise et al 2017).…”

“…Aubin et al 1985;Harvey and Dahlheim 1994), and a rare study involving three polar bears (Øritsland et al 1981). More recently, however, petroleum toxicity studies are limited to use of surrogates such as mink in place of sea otters (Bickham et al 1998;Mazet et al 2001;Schwartz et al 2004aSchwartz et al , 2004b and in vitro studies (Carvan et al 1995;Reichert et al 1999;Frouin et al 2010;Wise et al 2014;White et al 2017;Wise et al 2018a). The following sections review common impacts of petroleum exposure to marine mammals from both laboratory studies and oil spills.…”

Crude Oil and Dispersant Cause Acute Clinicopathological Abnormalities in Hatchling Loggerhead Sea Turtles (Caretta caretta)

“…Corexit alone after 4 days exposure was associated with more abnormalities than crude oil exposure alone. Combinations of crude oil and Corexit have exhibited enhanced toxicity in a wide range of organisms and cells, including rotifers, corals, fish embryos, juvenile mullet, lymphoproliferative response of dolphins, and others (1, 35–39). Corexit by itself damages epithelia (38), which could include skin, conjunctiva and gastrointestinal epithelia, consistent with observed hydration-related clinicopathological abnormalities.…”