99 Characterization of lipid and inflammatory profiles in horses with equine metabolic syndrome

Abstract

s / Journal of Equine Veterinary Science 35 (2015) 418e436 426 99 Characterization of lipid and inflammatory profiles in horses with equine metabolic syndrome S.E. Elzinga*, P.L. Wood , and A.A. Adams 1 University of Kentucky, Lexington, KY, USA; 2 Lincoln Memorial University, Harrogate, TN, USA Equine metabolic syndrome (EMS) is a growing problem in the equine industry that is linked to the potentially devastating condition laminitis. One of the defining characteristics of EMS is obesity. In humans and mice, a relationship between obesity, lipid profiles, and inflammation has been observed. As such, focus has shifted to using lipidomics to classify lipid profiles of individuals with metabolic dysfunction, but this technique has yet to be utilized in the horse. Moreover, previous work has yielded conflicting results about the inflammatory state of EMS animals. Considering that abnormal lipid profiles may contribute to altered cell signaling or increased inflammation, our goal was to examine possible differences in plasma lipid profiles of EMS horses compared with controls, as well as better understand their inflammatory state. To accomplish this, 23 age-matched mixed sex and breed horses (13 ± 3 years old) were selected in the spring of 2014 from the University of Kentucky’s herd. Of the horses, 9 were classified controls and 14 EMS. EMS was determined by the presence of hyperinsulinemia, general or regional obesity, and history of laminitis. All horses were maintained on a diet of mixed grass hay and had access to water and a mineral block ad libitum. Prior to blood sample collection horses were weighed, and average body condition (BCS) and cresty neck score (CNS) was calculated from 3 trained investigators. Following fasting, serum and plasma sample collection was performed via jugular venipuncture and an oral sugar test was administered. Serum was analyzed for insulin, leptin, triglyceride, cholesterol, and nonesterified fatty acid (NEFA) concentrations. Plasma samples were used to isolate peripheral blood mononuclear cells for cytokine protein concentration via flow cytometry and gene transcription via RT-PCR. Plasma was utilized for lipidomic analysis. Data were analyzed using SIGMASTAT version 3.1 by 2 way ANOVAwith fixed effects set as EMS vs control and age. As expected, EMS horses had increased BCS, CNS, basal insulin, and insulin post administration of oral sugar (P 0.05) differences between the 2 groups, however high variability may have influenced results. Lipidomics analysis revealed significantly elevated (P < 0.05) plasma tri-, di-, mono-acylglycerides, and ceramide in EMS horses, but lower sphingomyelins, suflatides, and choline plasmalogens. Thus, EMS horses have differences in their lipid profiles compared with controls.