Abstract
Equine atypical myopathy (AM) is a severe environmental intoxication linked to the ingestion of protoxins contained in seeds and seedlings of the sycamore maple (Acer pseudoplatanus) in Europe. The toxic metabolites cause a frequently fatal rhabdomyolysis syndrome in grazing horses. Since these toxic metabolites can also be present in cograzing horses, it is still unclear as to why, in a similar environmental context, some horses show signs of AM, whereas others remain clinically healthy. Label-free proteomic analyses on the serum of 26 diseased AM, 23 cograzers, and 11 control horses were performed to provide insights into biological processes and pathways. A total of 43 and 44 differentially abundant proteins between "AM vs cograzing horses" and "AM vs control horses" were found. Disease-linked changes in the proteome of different groups were found to correlate with detected amounts of toxins, and principal component analyses were performed to identify the 29 proteins representing a robust AM signature. Among the pathway-specific changes, the glycolysis/gluconeogenesis pathway, the coagulation/complement cascade, and the biosynthesis of amino acids were affected. Sycamore maple poisoning results in a combination of inflammation, oxidative stress, and impaired lipid metabolism, which is trying to be counteracted by enhanced glycolysis.