Temporal aspects of laminar gene expression during the developmental stages of equine laminitis.

The research investigates the activities of various genes during the early stages of equine laminitis, a painful and debilitating condition affecting a horse’s foot. Using 3000 gene transcripts, the study maps changes in gene expression caused by a laminitis-inducing agent against a control over different time intervals.

Objectives and Methodology

• The study aimed to understand the molecular mechanisms behind the development of equine laminitis, a disease that weakens the bond between the hoof wall and distal phalanx of a horse.
• An equine-specific cDNA microarray was used, which consisted of transcripts for over 3,000 genes. The objective was to observe the changes in gene expression in the horse’s laminar tissues between 1.5, 3, and 12 hours after administration of either a laminitis-causing agent such as black walnut heartwood extract (BWHE), or an equal volume of water as a control.

Findings

• As early as 1.5h after BWHE administration, pro-inflammatory genes associated with leukocyte activation and emigration, including MCP-3/CCL7, MCP-1/CCL2, IP-10/CXCL10 and ICAM-1 were up-regulated in the test subjects.
• The experiment also discovered that the expression of B-cell-specific transcripts such as Ig-gamma 3, Ig-gamma 1, and lambda-light chain, were decreased in the laminar tissues at both 1.5 and 3 hours after BWHE administration.
• Interestingly, at the outset of Obel grade 1 lameness in horses given BWHE, an increase in the expression of other genes involved in inflammatory processes was observed. These include genes that regulate inflammation such as serum amyloid A, calgranulin C, NFAT-activation molecule 1, and inter-alpha-trypsin inhibitor, amongst others.
• Also, genes that work to counterbalance the destructive effects of inflammation, such as those active in antioxidant responses, matrix turnover, and anti-microbial responses, were found to be up-regulated.

Conclusion

• The study concludes that certain pro-inflammatory genes, those that promote activation and extrication of leukocytes, antimicrobial activities, and destruction of the lamellar basement membrane, are induced during the development of laminitis in response to administration of BWHE.
• This research provides important insights into the molecular basis of equine laminitis that can aid in the development of better diagnostic techniques and treatment modalities.