Abstract
IntroductionPhotosensitization is a common clinical sign in cows suffering from liver damage caused by the mycotoxin sporidesmin. This disease, called facial eczema (FE), is of major importance in New Zealand. Current techniques for diagnosing animals with subclinical sporidesmin-induced liver damage (i.e. without photosensitization) are nonspecific. In addition, little is known of the mechanisms involved in sporidesmin resistance, nor the early effects seen following low-dose sporidesmin intoxication.ObjectiveThe objective of this study was to identify individual metabolites or metabolic profiles that could be used as serum markers for early stage FE in lactating cows.MethodsResults are presented from a 59-day sporidesmin challenge in Friesian-cross dairy cows. Serum metabolite profiles were obtained using reversed phase ultra-performance liquid chromatography (UPLC) electrospray ionization mass spectrometry (MS) and UPLC tandem MS. Multivariate and time series analyses were used to assess the data.ResultsStatistical analysis, both with and without the temporal component, could distinguish the profiles of animals with clinical signs from the others, but not those affected subclinically. An increase in the concentrations of a combination of taurine- and glycine-conjugated secondary bile acids (BAs) was the most likely cause of the separation. This is the first time that MS methods have been applied to FE and that bile acids changes have been detected in cattle exposed to sporidesmin.ConclusionsIt is well known that BA concentrations increase during cholestasis due to damage to bile ducts and leakage of the bile. This is the first study to investigate metabolomic changes in serum following a sporidesmin challenge. Further work to establish the significance of the elevation of individual BAs concentrations in the serum of early-stage sporidesmin-poisoned cows is necessary.
Highlights
Photosensitization is a common clinical sign in cows suffering from liver damage caused by the mycotoxin sporidesmin
Sporidesmin, a mycotoxin produced by the saprophytic fungus, Pithomyces chartarum, is the cause of liver and bile duct damage that leads to elevated blood phytoporphyrin concentrations and a secondary photosensitization disease known as facial eczema (FE)
There is a clear difference between groups (p < 0.0001) when compared to a baseline model with a common trend for all groups and this is primarily due to the clinical group differing (Fig. 1) from other groups
Summary
Photosensitization is a common clinical sign in cows suffering from liver damage caused by the mycotoxin sporidesmin This disease, called facial eczema (FE), is of major importance in New Zealand. An increase in the concentrations of a combination of taurine- and glycine-conjugated secondary bile acids (BAs) was the most likely cause of the separation This is the first time that MS methods have been applied to FE and that bile acids changes have been detected in cattle exposed to sporidesmin. Conclusions It is well known that BA concentrations increase during cholestasis due to damage to bile ducts and leakage of the bile This is the first study to investigate metabolomic changes in serum following a sporidesmin challenge. Sporidesmin, a mycotoxin produced by the saprophytic fungus, Pithomyces chartarum, is the cause of liver and bile duct damage that leads to elevated blood phytoporphyrin concentrations and a secondary photosensitization disease known as facial eczema (FE). No data has been published on FE research using the modern techniques of metabolomics
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