Oxidative stress indicators in human and bottlenose dolphin leukocytes in response to a pro-inflammatory challenge

Marine mammals undergo cycles of tissue ischemia and reperfusion during the dive response.Reperfusion injury can result in oxidative tissue damage and the activation of a pro-inflammatory immune response.The risk of oxidative damage is reduced by antioxidants.Our hypothesis is that the reported higher antioxidant defenses within marine mammal tissues provide additional protection in situations that produce oxidative stress,like inflammation,in comparison to terrestrial mammal tissues.Leukocytes were isolated from the whole blood of Pacific bottlenose dolphins(Tursiops truncatus gilli)and humans(Homo sapiens)and were exposed to lipopolysaccharides(LPS,10μg/mL)in vitro to simulate a pro-inflammatory challenge.Oxidative stress indicators,including superoxide radical(O_(2)^(•−))production,activities of superoxide dismutase(SOD),catalase(CAT),glutathione peroxidase(GPx),glutathione reductase(GR),and glutathione S-transferase(GST),as well as oxidative protein damage,were quantified by spectrophotometry.Following 48 h under experimental conditions,bottlenose dolphin leukocytes produced 1.9 times more O_(2)^(•−)but displayed 2.0 times lower protein carbonyl concentrations compared to human leukocytes.Following 48 h under experimental conditions,bottlenose dolphin leukocytes displayed 7.9,2.0,11.1,and 3.3 times more activities of CAT,GPx,GR,and GST,respectively,compared to human leukocytes.These results suggest that,under cell culture conditions,the antioxidant defenses in bottlenose dolphin leukocytes provide additional protection against pro-inflammatory challenges in comparison to human leukocytes,likely as an adaptive advantage.