Horses are exposed every day to the risk of injury or infection but, because their bodies
respond by creating protective inflammation, they can naturally repair injured tissue and
deal with the cause of the problem without veterinary intervention.
Neutrophils, a type of white blood cell, play a vital role in this process. However, if the accumulation and activation of these neutrophils is not properly regulated by the animal's body, they can actually become part of the problem, particularly in inflammatory diseases such as colic, laminitis and heaves.
The Horse Trust is funding a project, led by Dr Fiona Cunningham at the Royal Veterinary College, which will look at how movement of horse neutrophils out of the circulatory system and through tissue to the site of inflammation are controlled by two chemical mediators produced naturally in the horse's body: interleukin-8, which is produced in inflamed tissue, and annexin 1, much of which is stored in the neutrophils. Both are thought to modulate this migration of neutrophils to the site of inflammation.
A link between the amount of annexin 1 in neutrophils and circulating levels of cortisol will also be investigated, as this naturally occurring anti-inflammatory steroid - like other steroids of the same type - acts, in part, by releasing annexin 1.
The third part of the project will investigate the role played by protein kinase C, a family of intracellular enzymes, in relation to the actions of Interleukin-8. In humans, it is involved in the signalling process and may have the same function in the horse's immune response.
The studies will help to establish if neutrophil accumulation can be regulated in new ways that could be used eventually to design different approaches to treating inappropriate inflammatory responses associated with some common diseases of the horse.
Further, if a correlation with cortisol is established, the measurement of neutrophil annexin 1 could provide a way of identifying individual animals in whom the protective inflammatory response is less effective and for which early veterinary intervention will be beneficial.
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