Plasma Lipidomic and Inflammatory Cytokine Profiles of Horses With Equine Metabolic Syndrome

Abstract

Equine metabolic syndrome (EMS) is a growing problem in the equine industry, particularly considering it is a risk factor for the development of laminitis. Equine metabolic syndrome is similar to metabolic syndrome in humans, which is associated with abnormal circulating plasma lipid concentrations. Thus, our objectives were to characterize the plasma lipid profiles, or lipidome, of horses with EMS compared to non-EMS controls and to further characterize the inflammatory state of these horses. Twenty-three horses of mixed breed and sex were selected. Of these, 14 were classified as EMS and 9 as non-EMS controls. Equine metabolic syndrome was determined by insulin resistance, general or regional adiposity, and a history of or predisposition to laminitis. Fasting serum and plasma samples were collected via jugular venipuncture. Serum samples were used to determine insulin, leptin, triglyceride, cholesterol, and nonesterified fatty acid concentrations. Heparinized plasma samples were used to isolate peripheral blood mononuclear cells for inflammatory cytokine determination and ethylenediaminetetraacetic acid plasma to analyze lipidomes. Equine metabolic syndrome horses had increased serum leptin and triglycerides. Plasma lipidomic analysis indicated that EMS horses had elevated triacylglycerides, diacylglycerides, monoacylglycerides, and ceramide compared to control horses. They had lower plasma sphingomyelins, suflatide, and choline plasmalogens. Peripheral blood mononuclear cell analysis for cytokine protein concentration via flow cytometry and gene transcription via real-time polymerase chain reaction showed no differences between the two groups; however, high variability may have influenced results. These data demonstrate that EMS horses have differences in their plasma lipidome compared to controls, similar to what has been observed in humans with metabolic syndrome.