Ultrastructural examination of basement membrane pathology in horses with insulin-induced laminitis.

The research article investigates the changes in the ultrastructure and morphometry of the lamellar basement membrane in horses during the acute phase of insulin-induced laminitis.

Introduction and Aim

• The research focuses on laminitis, a disease affecting horses where the lamellae – a dermoepidermal layer in the hooves – fails. The basement membrane (BM), an interface between the epidermis and dermis, shows signs of pathology during acute laminitis.
• Interestingly, there seems to be less basement membrane damage in ponies with insulin-associated laminitis. The aim of the study, therefore, was to explore changes in the lamellar basement membrane’s ultrastructure and morphometry during the acute phase of insulin-induced laminitis in horses.

Methods

• The researchers examined lamellar tissue from the left forefoot of three horses with acute hyperinsulinemic laminitis. This was then compared to tissue from normal horses.
• The team used transmission electron microscopy to investigate the lamellar BM width and the density of hemidesmosome (HD), a type of protein structure. These assessments were made every 5 micrometers along approximately 200 micrometers of secondary epidermal lamellar BM.

Results

• The findings indicate extensive disorganization in the BM zone of treated horses, marked by a loss of uniformity of the lamina lucida and lamina densa, fragmentation and disorientation of HDs, and cytoskeletal disengagement of the HDs.
• The average lamellar BM width was found to be twice as large in treated horses as in the control group. Similarly, the average HD density was halved in the treatment group compared to the controls.
• The reduced number of HDs may contribute to the weakening of the dermoepidermal junction and lamellar failure.

Conclusion and Further Implications

• The disassembly of HDs during excessive cellular proliferation, secondary to hyperinsulinemia, could explain the loss of HDs.
• Overall, more research into the cause and effect of BM dysfunction during hyperinsulinemic laminitis in horses could lead to a better understanding of the disease and potentially improved treatments.