Genome-Wide Transcriptome Profiling of Laminar Tissue During Early Stages of Carbohydrate Overload-Induced Equine Laminitis

Abstract

s Vol 30, No 2 (2010) 105 Veterinary Science, The University of Queensland, St. Lucia, Queensland, Australia TAKE HOME MESSAGE Proteomic analysis of lamellar tissue is a useful tool for investigating the molecular mechanisms of laminitis pathogenesis. INTRODUCTION Hyperinsulinemia resulting from the prolonged euglycemic-hyperinsulinemic clamp (pEHC) induces laminitis within 48 h in horses. However, the molecular mechanism linking hyperinsulinemia to lamellar pathology is unknown. MATERIALS & METHODS (INCLUDING STATISTICAL ANALYSES) Four Standardbred horses were subjected to pEHC and 4 matched controls were sham-treated with saline. Horses were euthanized at 48h and lamellar tissue was extracted and frozen in liquid nitrogen. Protein was extracted from frozen tissue, separated by SDS-PAGE, and proteins with a molecular weight between 20 50 kDa were trypsin digested and peptides identified by HPLC/MS/MS and search of the equine protein database. Proteins were identified with probabilities R99%, and counts of peptide spectra for each protein were used to quantitate differences in protein abundance using Scaffold 2 software and differences between groups were determined by independent t tests. RESULTS 670 proteins were identified and 17 proteins were differentially expressed between treatment and control groups (P < 0.05). Differences in protein expression were indicative of increased translation, intracellular trafficking, immune response, oxidative stress, and cellular proliferation; and decreased post-translational modifications and structural or cell adhesion proteins. DISCUSSION Further investigation into proteomic changes during laminitis, including expanding the range of molecular weights analyzed and evaluating additional time points and models of laminitis, will provide invaluable data for determining the molecular mechanisms of laminitis pathogenesis. CLINICAL RELEVANCE Understanding the mechanisms of laminitis pathogenesis will facilitate the prevention, management and treatment of this devastating disease. CONCLUSION Differences in lamellar protein expression occur during hyperinsulinemia-induced laminitis. Genome-Wide Transcriptome Profiling of Laminar Tissue During Early Stages of Carbohydrate Overload-Induced Equine Laminitis Jixin Wang, Britta Leise, Ashley Gustafson, Bindu Nanduri, James Belknap, and Bhanu Chowdhary, Department of Veterinary Integrative Biosciences, College of Veterinary Medicine & Biomedical Sciences, Texas AM p value < 0.01) were identified to detect biological pathways and networks (Ingenuity Pathway Analysis IPA). RESULTS Approximately 250 DE genes were identified: response to stimulus, apoptotic program and immune-related genes were among those over-represented. The IPA analysis depicted pathways potentially involved in laminitis, including dysregulation of glycolysis and gluconeogenesis. Fifteen DE genes were validated by quantitative real-time PCR. DISCUSSION Discerning the potential role of DE genes in relevant pathways and networks reveals potential mechanisms of disease pathogenesis. Analysis of earlier timepoints will be useful in understanding the sequence of events underlying laminitis pathogenesis. CLINICAL RELEVANCE Identification of key genes associated with progression and severity of laminitis can serve as potential targets for novel therapeutic interventions. CONCLUSION This preliminary study provides a genomewide overview of differences in gene expression patterns in laminitic tissue at 48h of hyperinsulinemia, relative to controls. Clinical and Matrix Metalloproteinase Inhibitory Effects of Pentoxifylline on Carbohydrate Overload Laminitis: Preliminary Results Lee Ann Fugler, DVM, PhD, Susan C. Eades, DVM, PhD, Catherine E. Koch, MA, and Mike L. Keowen, Equine Health Studies Program, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA TAKE HOME MESSAGE Preliminary data suggests that the intravenous administration of PTX may be effective in the prevention and/or treatment of CHO-induced equine laminitis. INTRODUCTION MMPs are increased in equine laminitis, and PTX is a potent MMP inhibitor. Therefore, we hypothesized that the intravenous administration of PTX would prevent or decrease the severity of lameness during CHO laminitis. MATERIALS AND METHODS Data has been collected from 10 Thoroughbred geldings (n 1⁄4 5 control, n 1⁄4 5 PTX) administered a carbohydrate gruel via nasogastric tube. Clinical parameters and digital venous samples were collected for 60 hours following