2016 ACVIM Forum Research Abstract Program

The basal expression characterized by these data provide a foundation for future research into the roles of specific miRNAs in equine inflammatory responses. miR-155 is the principal LPSinduced miRNA in horses, as in humans and mice. This miRNA has documented roles in TLR4 signaling regulation, including enhancement of TNFa translation and suppression of intermediate signal transduction proteins. It is thus likely to influence the magnitude and nature of the acute inflammatory response to LPS in the horse, and could be a target for immune modulatory interventions. It may also prove a useful marker of TLR activation. Further research will be necessary to validate expression changes in a wider sample set, investigate targets and functions of these miR-NAs in horses, and to establish roles in naturally occurring disease. Airway neutrophilia is a characteristic finding of severe equine asthma (heaves), a common and incurable condition of horses. However, how polymorphonuclear neutrophils (PMNs) contribute to the disease remains poorly understood. "Low-Density Granulocytes" (LDGs), a subpopulation of PMNs, have been suggested to have strong pro-inflammatory properties, which can promote the recruitment of PMNs in an autocrine manner and thus amplifying the inflammatory response. We therefore hypothesized that LDGs are increased in the blood of heaves-affected horses compared to healthy subjects.