Collagen is an
extracellular matrix protein present in the skin, tendon, cartilage and bone.
Collagen peptides (CP) are produced by the hydrolysis of
gelatin (heat-denatured
collagen) by
proteases and are utilized as a component of nutraceuticals. The current study investigated the effect of CP on the articular cartilage of OA by evaluating the serum levels of
biomarkers (CTX-II for
type II collagen degradation and CPII for
type II collagen synthesis), histopathological changes (Mankin score, based on the
toluidine blue staining of
proteoglycans), and immunohistochemical staining of
matrix metalloproteinase (MMP)-13 and
type II collagen, using a rat experimental
osteoarthritis (OA) model. Anterior cruciate ligament transection (ACLT) was performed on the right knee joint to surgically induce OA. Animals were divided into four groups: Control group (Control),
sham-operated group (
Sham), ACLT group without
collagen peptide (ACLT group) and ACLT group with
oral administration of CP (CP group). ACLT induced histological damages and significantly increased the Mankin score (P<0.05). However, CP administration markedly suppressed the Mankin score, although this difference was not significant. In addition, serum CTX-II levels were significantly decreased in CP group compared with those in the ACLT group (P<0.05). By contrast, serum CPII levels did not differ significantly among the four groups. Moreover, immunohistochemical staining of
type II collagen and MMP-13 (an important
type II collagen-degrading
enzyme) indicated that the amount of
type II collagen increased, whereas the number of MMP-13 positive chondrocytes decreased in the CP group compared with ACLT group. These observations suggest that CP has the potential to exert chondroprotective action on OA by inhibiting MMP-13 expression and
type II collagen degeneration.