PR001477 (Project)

Description:The fungal disease of bats, white-nose syndrome (WNS), is caused by the pathogen Pseudogymnoascus destructans (Pd). WNS-positive little brown bats (Myotis lucifugus) can exhibit an immune response during infection that include increases in cytokine and pro-inflammatory mediator gene levels. While bioactive lipid mediators (oxylipins) formed by enzymatic oxidation of polyunsaturated fatty acids (PUFAs) can contribute to this type of immune response, their role in WNS pathophysiology have not been investigated. Nonenzymatic conversion of PUFAs can also occur due to reactive oxygen species (ROS), however, these enantiomeric isomers will lack the same signaling properties. In this study, we performed a series of targeted lipidomic approaches on laboratory Pd-inoculated bats to assess changes in their splenic lipidome, including the formation of lipid mediators at early stages of WNS. Hepatic lipids previously identified were also resolved to a higher structural detail. We compared WNS-susceptible M. lucifugus to a WNS-resistant species, the big brown bat (Eptesicus fuscus). Altered splenic lipid levels were only observed in M. lucifugus, with lower total levels of glycerophospholipids (GPs) and free fatty acids (FFAs) in the Pd-inoculated group compared to the sham-inoculated group. Lower concentrations of splenic GPs were observed in lipid compounds containing 18:2 or saturated acyl chains. Differences in splenic FFAs included both omega-3 (including docosahexaenoic acid [DHA]) and omega-6 compounds. Increased levels of an enantiomeric monohydroxy DHA (4-hydroxydocosahexaenoic [HDoHE], 10-HDoHE, and 13-HDoHE) mixture, suggesting nonenzymatic formation, along with 6-keto-PGF1a were found. Changes in previously identified hepatic lipids were confined to omega-3 constituents. Together, these results suggest that increased oxidative stress, but not an inflammatory response, is occurring in bats at early stages of WNS that proceeds fat depletion.