Endocrine Abstracts

Laminitis, an inflammatory condition of the sensitive and specialised architecture (the laminae) in the equine hoof, can be induced by over-ingestion of non-structural carbohydrates (NSC) from spring/summer pasture. Some equids that are predisposed to laminitis appear to share characteristics described in human patients with metabolic syndrome. We investigated if adipose tissue from laminitis prone equids (LP) functions differently from non-laminitis prone equids (NL), by examining gene expression in subcutaneous adipose tissue from healthy LP and NL (n=6 each group), obtained in the summer and winter (season) and following increased NSC consumption (dietary intervention: 7 days in the winter). Genes and signalling pathways that differed between group and season/dietary intervention were compared using a 44K equine expression microarray. Data were analysed in GeneSpring and Ingenuity Pathway Analysis. Genes with greater than twofold, P<0.01 were considered significant. The most significant differences in global gene expression were observed between summer and winter, with 244 and 174 genes differentially expressed in the NL and LP respectively. The LP and NL groups showed significant differences between groups in the summer (141 genes), whereas the two groups were more similar in the winter (40 genes significantly different) when laminitis is uncommon. Eight of the top ten upregulated molecules and three of the top five canonical pathways that differed between LP and NL in the summer were associated with inflammation and/or immunity. There were significantly fewer changes in gene expression following dietary intervention (27 and 44 genes in PL and NL respectively), and only 23 genes differed between the groups after dietary intervention. LP ponies appear to have a different adipose tissue profile to NL, particularly in the summer. Inflammatory genes and pathways were significantly over-represented in the LP group suggesting higher baseline levels of inflammation or priming of inflammatory pathways may contribute to a predisposition to laminitis.