Objectives: To determine the temporal progression of lamellar BM changes and whether laminin-332 (Ln-332) 2 cleavage products are generated during laminitis development.
Methods: Eight clinically normal Standardbred horses were allocated into treatment (n = 5) or sham (n = 3) groups. The treatment group received, via nasogastric intubation, an oligofructose (OF) bolus (10 g/kg bwt) while the sham group was given water. Laminitis induction proceeded for 48 h followed by euthanasia. Lamellar biopsies were obtained prior to dosing and at intervals during the treatment period for analysis (at 12, 18, 24, 30 and 36 h and at 48 h following euthanasia).
Results: Changes in lamellar collagen type IV and Ln-332 were first observed at 12 h post dosing. A unique pattern of reactivity for the Ln-332 2 antibody D4B5 occurred, in which reactivity was observed only in lamellar tissue affected by laminitis. No bioactive Ln-332 2 proteolytic fragments were detected in lamellar samples.
Conclusions: Basement membrane changes occurred early during the laminitis process. Direct Ln-332 2 cleavage to release biologically active products did not appear to occur. Thus loss of stability or protein interaction of the BM is probably responsible for the 2 specific reactivity observed.
Potential relevance: Basement membrane changes may a first step in lamellar failure occurring prior to detection with conventional methods. Thus, more sensitive detection methods of BM changes are required to study laminitis development.
