Microarray Analysis of Gene Expression in Laminar Tissue From Horses After Carbohydrate Overload

s Vol 30, No 2 (2010) 109 the disease process and that could serve as new targets for therapeutic intervention. Laminar Inflammatory Gene Expression in the Carbohydrate Overload Model of Equine Laminitis B.S. Leise, P.J. Johnson, R.R. Faleiros, S.J. Black, and J.K. Belknap, The Ohio State University College of Veterinary Medicine, Columbus, OH, University of Missouri College of Veterinary Medicine, Columbia, MO, Universidade Federal de Minas Gerais, Brazil, University of Massachusetts, Amherst, MA TAKE HOME MESSAGE Laminar inflammation is present but delayed in the CHO model of laminitis when compared to BWE. INTRODUCTION The purpose of this study was to determine if a similar pattern of laminar inflammation characterized by pro-inflammatory mediator expression occurs in the CHO model of laminitis as previously described in the BWE model. MATERIALS AND METHODS Real time-quantitative PCR for selected pro-inflammatory mediators was performed on laminar samples from sixteen horses administered carbohydrate (DEV group, n 1⁄4 8[onset of fever], OG1 group, n 1⁄4 8 [onest of lameness]), and eight horses administered water (CON) 24 hours after administration of deionized water. RESULTS Increased mRNA concentrations (P < 0.05) for IL-1b IL6, IL-12p35, COX-2, E-selectin, and ICAM-1 were present in laminae from horses with OG1 lameness, but not at the DEV time, when compared to the CON horses. No differences between the groups were found for IL-2, IL-10, TNFa, IFNg, or COX-1 at either the DEV or OG1 time points. DISCUSSION There is a marked difference in the temporal pattern of inflammatory events between the BWE and CHO, with many events peaking early in the developmental stages in the BWE model compared to the majority of events appearing to occur simultaneously at the onset of lameness in the CHO model. This suggests that, in addition to circulating inflammatory molecules, there may be a local phenomenon (i.e. alterations in blood flow or hypoxia) in the CHO model resulting in the simultaneous onset of multiple laminar events including endothelial activation, leukocyte emigration, and pro-inflammatory cytokine expression. CLINICAL RELEVANCE The delayed onset of laminar inflammatory events in the CHO laminitis model may indicate that the clinician has a substantial time period to address inflammatory signaling in septic horses at risk of laminitis prior to the onset of irreversible inflammatory injury. CONCLUSIONS Although the onset of cytokine expression is delayed in the CHO model compared to the BWE model a similar prominent laminar inflammatory response occurs at onset of lameness, further supporting the need to address inflammatory signaling in the acute clinical case of laminitis. Laminar Regulation of STAT1 and STAT3 in the Black Walnut Extract and Carbohydrate Induced Models of Laminitis B.S. Leise, M. Watts, E. Tanhoff, C. Yin, A. Pettigrew, P. Johnson, S. Black, and J. Belknap, The Ohio State University College of Veterinary Medicine, Columbus, OH, University of Missouri College of Veterinary Medicine, Columbia, MO, University of Massachusetts, Amherst, MA TAKE HOME MESSAGE Activation of STAT1 and STAT3 occurs in both the BWE and CHO model of laminitis and is a possible therapeutic target in laminitis. INTRODUCTION Similar to sepsis-related organ injury in humans, laminar injury in experimental models of laminitis is associated with marked increases in cytokine expression. JAK-STATs are well known cytokine activated signaling pathways that are reported to play an important role in regulating sepsis-related inflammation and damage in other species. The objective of this study was to determine the regulation of STAT1 and 3 signaling in the laminae in the BWE and CHO model of laminitis. MATERIALS AND METHODS Western hybridization analysis was performed to determine concentrations of tyrosineand serine-phosphorylated STAT1 and STAT3 from archived laminar tissue samples from previous BWE and CHO overload protocols. Real time-quantitative PCR was also performed to assess