Research produces valuable insights into the cause of laminitis
Laminitis is the inflammation of the laminae, the soft tissue structures that connect the hoof wall to the coffin bone and other structures in the horse’s foot. The inflammation and damage to the laminae can cause extreme pain and leads to instability in the foot which can be fatal in severe cases.
The cause of endocrine laminitis (the most common form of this disease) has been linked to high levels of the hormone insulin for some time. This has been seen horses and ponies at risk of laminitis producing large spikes of insulin in their blood after consuming carbohydrates, particularly starch and simple sugars. However, the mechanism by which insulin (a hormone which clears glucose from the blood), can lead to laminitis has been the subject of much academic debate in recent years. What has puzzled researchers, is that hormones like insulin must interact with a specific receptor on the surface of cells but there appears to be no insulin receptors on the hoof lamellar cells.
However, recent research conducted by world leading equine expert Professor Simon Bailey and PhD candidate Courtnay Baskerville in conjunction with the Waltham Centre for Pet Nutrition has focused on growth factor IGF-1, which has a similar structure to insulin and exists on the lamellar cells. By developing a method of culturing lamellar epithelial cells in the laboratory, they were able to test the effect of increasing concentrations of insulin. The results showed that insulin cross stimulated IGF-1 receptors, which subsequently caused the lamellar cells to proliferate. Additionally, it was found that this effect could be prevented using an antibody that specifically blocks the IGF-1 receptor.
The findings from this study provide one possible explanation of how insulin may directly affect lamellar epithelial cells, which is promising for future work looking to reduce the severity and impact of laminitis by targeting the IGF-1 receptors.