Differences in extracellular matrix proteins between Friesan horses with aortic rupture, unaffected Friesans and Warmblood horses
Ploeg, A. Gröne, C. H. A. van de Lest, V. Saey, L. Duchateau, P. Wolsein, K. Chiers, R. Ducatelle, P. R. van Weeren, M. de Bruijn and C. Delesalle
This post-mortem study aimed to determine whether there is a breed-related defect in the extracellular matrix (ECM) in Friesans which predisposes them to aortic rupture. Tissue from 18 affected Friesans, 10 unaffected Friesans and 30 Warmblood horses (in which aortic rupture is uncommon) was analysed. ECM components (amino acids concentrations, collagen cross-linking, metalloproteinase activity and glycosaminoglycan content) were measured in the aortic wall and the deep digital flexor tendon (DDFT).
There was no difference in total collagen content between the three groups. At the aortic rupture site in affected Friesans collagen hydroxylation, MMP activity, elastin and collagen cross-linking were significantly higher than at the same site in unaffected horses. There were no differences in the aorta ECM between Warmbloods and unaffected Friesans.
Collagen lysine hydroxylation was significantly lower in the DDFT of unaffected Friesans compared to Warmbloods suggesting significant differences in collagen metabolism between the two breeds. There was no difference at the DDFT site between affected and unaffected Friesans, with differences only seen at the aortic rupture site, suggesting the absence of a generalised ECM disorder in the breed.
Significant remodelling has been demonstrated at the site of aortic rupture in Friesans; these changes are not present at other sites in the body or in unaffected Friesans. Potential differences in collagen metabolism between Friesans and other breeds warrant further investigation.