The Effectiveness of Specific Collagen Peptides on Osteoarthritis in Dogs-Impact on Metabolic Processes in Canine Chondrocytes

In clinical trials over the past decade, the beneficial effect of orally administered collagen peptides in osteoarthritic dogs has been clearly demonstrated [1] [2] [3]. Although a statistically significant improvement in the lameness and vitality of dogs in general has been documented, the mode of action of the collagen peptide treatment is still under discussion. A previous study [3] indicated that the reduction in lameness and increased mobility in dogs after collagen peptide treatment were associated with a statistically significantly lowered plasma content of MMP-3, which is involved in collagen degradation. In addition, the content of the MMP-antagonist TIMP-1 increased slightly after collagen peptide supplementation, suggesting a direct impact on the cartilage metabolism, particularly on the decrease of extracellular matrix degradation. Based on these findings, the impact of specific collagen peptides (PETA-GILE?) on cartilage metabolism was tested in canine chondrocytes in the current investigation. In addition to the biosynthesis of various matrix molecules (type II collagen, aggrecan and elastin), the RNA profile of inflammatory cytokines and degenerative matrix molecules was investigated. The results showed clearly that the supplementation of specific collagen peptides reduced catabolic processes, as indicated by a statistically significant decrease in inflammatory cytokines and proteases in canine chondrocytes compared with untreated control experiments. In addition, a statistically significantly enhanced biosynthesis of type II collagen, elastin, and aggrecan was observed. Hence, the current data supports the suggested anti-inflammatory effect of specific collagen peptides, but also clearly demonstrates a pronounced stimulatory impact on matrix molecule synthesis. A combination of both observed effects might help to explain the previously reported clinical improvements after collagen peptide supplementation. Furthermore, the beneficial effect of the specific collagen peptides was also confirmed in case reports on osteoarthritic dogs that demonstrated decreased lameness and increased vitality in the affected animals after PETAGILE treatment.

Interaction of the α2A domain of integrin with small collagen fragments

We here present a detailed study of the ligand-receptor interactions between single and triple-helical strands of collagen and the α2A domain of integrin(α2A),providing valuable new insights into the mechanisms and dynamics of collagen-integrin binding at a sub-molecular level.The occurrence of single and triple-helical strands of the collagen fragments was scrutinized with atom force microscopy(AFM)techniques.Strong interactions of the triple-stranded fragments comparable to those of collagen can only be detected for the 42mer triple-helical collagen-like peptide under study(which contains 42 amino acid residues per strand)by solid phase assays as well as by surface plasmon resonance(SPR)measurements.However,changes in NMR signals during titration and characteristic saturation transfer difference(STD)NMR signals are also detectable whenα2A is added to a solution of the 21mer single-stranded collagen fragment.Molecular dynamics(MD)simulations employing different sets of force field parameters were applied to study the interaction between triple-helical or single-stranded collagen fragments withα2A.It is remarkable that even single-stranded collagen fragments can form various complexes withα2A showing significant differences in the complex stability with identical ligands.The results of MD simulations are in agreement with the signal alterations in our NMR experiments,which are indicative of the formation of weak complexes between single-stranded collagen andα2A in solution.These results provide useful information concerning possible interactions ofα2A with small collagen fragments that are of relevance to the design of novel therapeutic A-domain inhibitors.