Sphingolipidomics of Bovine Pink Eye: A Pilot Study

SIMPLE SUMMARY: The liquid tear film, which protects the eye from the environment, is a dynamic fluid containing a large number of complex lipids. Disruptions of these lipids by infections can result in damage to the eye and ultimately blindness. In this study we characterized various lipid subfamilies present in the tear film of the eye and the effect of pink eye infections in cattle. Our findings demonstrate that the pink eye infections dramatically decrease the levels of lipids in the tear film covering the eye and suggest that this is a major factor in the development of blindness in infected cattle. ABSTRACT: Sphingolipids are essential structural components of tear film that protect the surface of the eye from dehydration. A detailed analysis of the effects of pink eye infections on the sphingolipidome in cattle has not previously been undertaken. We recently published a new assay utilizing high-resolution mass spectrometric monitoring of the chloride adducts of sphingolipids that provides enhanced sensitivity and specificity. Utilizing this assay, we monitored decreases in the levels of tear film ceramides with short-chain fatty acids, hydroxy-ceramides, phytoceramides, and hydroxy-phytoceramides. Dihydroceramide levels were unaltered and increased levels of ceramides with long-chain fatty acids (24:0 and 24:1) were monitored in cattle with pink eye. The data from this pilot study (n = 8 controls and 8 pink eye) demonstrate a major disruption of the lipid tear film layer in pink eye disease, that can result in severe eye irritation and damage.