Characterisation and distribution of epidermal growth factor receptors in equine hoof wall laminar tissue: comparison of normal horses and horses affected with chronic laminitis.

This research article investigates the presence and role of epidermal growth factor (EGF) receptors in the hoof wall laminar tissue of horses, comparing healthy horses with those affected by chronic laminitis. The study found that EGF receptors are notably absent in horses suffering from chronic laminitis and are primarily located in the secondary epidermal laminae in normal horses. The researchers propose the possibility of an EGF-mediated response contributing to the hyperproliferative response characteristic of chronic laminitis.

Epidermal Growth Factor Receptors in Equine Hoof Wall Laminar Tissue

• The research paper details an investigation into the presence of EGF receptors in the hoof wall laminar tissue of horses. These receptors were found at concentrations comparable to those in the horse’s liver.
• Through Scatchard analysis, it was found that there were two classes of EGF binding sites in the plasma membranes from clinically normal horses: a high-affinity class and a more numerous low-affinity class.
• The dissociation constant of the low-affinity EGF-specific receptors is reported to be comparable with previously determined values for the EGF receptor, implying that the concentrations found in the hoof wall laminar tissue are usual and expected.

Variability in the High-Affinity Receptor Class

• However, significant variability was noticed between individual estimates for the dissociation constant of the high-affinity receptor class, meaning the researchers couldn’t accurately estimate these values.
• A discussion is noted on the possible reasons for this variability, although the specific details aren’t mentioned in the abstract.

Occurrence in Horses Affected by Chronic Laminitis

• The high-affinity binding sites were completely absent in the plasma membranes of horses affected by chronic laminitis.
• Also, it was seen that EGF receptors in tissues from horses with chronic laminitis were distributed uniformly over the hyperplastic epidermal keratinocytes, differing from their localisation primarily to the secondary epidermal laminae in healthy horses.
• Very little label was associated with the dermal or the keratinised primary epidermal laminae, which can contrast with the uniform distribution noted in tissues from horses with chronic laminitis.

Implications of the Research

• The findings from the research suggest that an EGF-mediated response might be involved in the hyperproliferative response, a characteristic of chronic laminitis.
• This could point towards an underlying mechanism of this disease progression, presenting potential targets for therapeutic intervention in the future.