Evaluation of Peripheral Blood Neutrophil Functions after an Oral Carbohydrate Overload in Obese and Insulin Resistant Horses

Abstract

Background: Obesity and insulin resistance (IR) are conditions of increasing prevalence in populations of equids worldwide. The immune impairment described in metabolic dysfunction status in humans has been extensively reported with minimal data regarding horses. The objective of the study was to evaluate the effect of obesity as an isolated factor and in association with insulin resistance on apoptosis, phagocytosis and oxidative burst activity of neutrophils isolated from peripheral blood of lean and obese adult horses with or without insulin resistance, basally and after induction of hyperglycemia through an oral glucose test. Results: No differences in apoptosis were observed between experimental groups at any time point. Phagocytic capacity was significantly diminished at baseline in the obese-IR group (P<0.05) but increased after stimulation of hyperglycemia (P=0.007). Basal reactive oxygen species production differed significantly (P=0.0001) between the obese-insulin sensitive (IS) and lean-IS or obese-IR groups, and decreased significantly after stimulation of hyperglycemia in the lean-IS and obese-IS groups (P<0.05).Conclusions: Results from this study showed that both metabolic status itself, and acute hyperglycemia, are factors that influence PMNs functionality in horses, specifically phagocytosis and oxidative burst. This indicates the need for close monitoring of immune function in horses with inflammatory disease and concurrent obesity and insulin resistance.