Unilateral basement membrane zone alteration of the regenerated laminar region in equine chronic laminitis.

This research explores how the basement membrane zone (BMZ) in the foot of horses changes due to chronic laminitis, a common hoof disease, particularly during the recovery phase of this disease. The study reinforces that alterations in the BMZ are linked to both the development and recovery outcome of laminitis.

Research Context

• The basement membrane zone (BMZ) is found between the laminar epidermis and the laminar dermis of the laminar region in a horse’s foot. It consists of a basement membrane and various elements such as hemidesmosome and anchoring fibril.
• In the case of equine laminitis, a common and often debilitating hoof disease, alterations in the structure and features of this BMZ have been observed.
• The researchers aim to understand the structural changes in the BMZ during the post-laminitis recovery phase.

Methodology

• Three cases of equine chronic laminitis were studied at different time intervals – two weeks, four weeks, and three months after the onset of the disease. The researchers used pathological, immunohistochemical, and electron microscopic techniques for their assessment.
• They mainly examined the structure of regenerated laminar epidermis, the BMZ, and the presence of certain antibodies.

Key Findings

• In all three cases of laminitis, there was a regenerated laminar epidermis with proliferating keratinocytes. Yet, a structure called undeveloped secondary epidermal laminae (ud-SELs) was found in one side of primary epidermal laminae, especially in the deep area of the laminar region.
• The BMZ showed positive results for anti-type IV collagen, anti-type VII collagen, and anti-laminin 5 antibodies. This indicates a certain level of recovery in the BMZ.
• However, in partial BMZs adjacent to the ud-SELs, the BMZ was negative for the anti-type VII collagen and anti-laminin 5 antibodies. This indicates incomplete recovery in these specific regions.
• Also, key elements of the BMZ such as the anchoring fibrils and the hemidesmosomes were either absent or found in reduced levels. This again points to the lack of complete recovery.

Conclusions

• The study concludes that in chronic laminitis, even though there is an attempt to regenerate the BMZ, complete recovery does not occur, particularly on the unilateral side of laminar epidermis.
• This incomplete recovery may also be associated with the recurrence of the disease.