Equine laminitis: cleavage of laminin 5 associated with basement membrane dysadhesion.

The study focuses on laminitis in horses, a condition where the hoof’s laminar dermal-epidermal interface separates due to alterations in the structural proteins present in the basement membrane zone. The researchers used microscopy to examine damage in lamellar tissues, and they suggest that inhibiting certain proteins could prevent the progression of laminitis.

Research Objectives and Methods

• The study targeted an investigation into the harm to lamellar hemidesmosome and cytoskeleton, and how basement membrane dysadhesion occurs. The tools for these observations were light microscopy (LM) and immunofluorescence microscopy (IFM).
• The study used cryostat sections of lamellar tissues from 2 control and 6 Standardbred horses suffering from laminitis, which was induced using oligofructose. The specimens were observed using LM and IFM.
• The antibodies of Plectin, integrin alpha6, and BP230 were used to label intracellular plaque proteins of hemidesmosome. Meanwhile, anti-BP180 and anti-laminin 5 (L5) were used for labelling anchoring filament (AF) proteins. The cytoskeleton intermediate filaments were labelled with anti-cytokeratin 14.
• The primary antibodies of selected sections were double labelled to show protein co-localisation.

Results

• Laminitis was found to result in the reduction of transmembrane integrin alpha6, along with the AF proteins BP180 and L5. There was also a failure of co-localisation of BP180 and L5. However, proteins of the inner hemidesmosomal plaque, which are plectin and BP230, remained unaffected.
• The loss of co-localisation of L5 and BP180 suggests that during the acute phase of laminitis, L5 is cleaved. As a result, the AFs connecting the epidermis to the dermis fail, leading to separation at the lamellar dermo-epidermal junction.

Conclusions

• Based on the study’s findings, suppressing or inhibiting metalloproteinase activity may prevent L5 cleavage, and thereby the lamellar dermo-epidermal separation of laminitis. By showing how specific proteins function and are altered during laminitis, these insights could lead to potential therapeutic approaches to treat this condition in horses.