The aim of the study was to correlate the immunohistochemical expression of cartilage intermediate layer protein 2 (CILP-2) and discoidin domain receptor 2 (DDR2), and the ultrastructural changes in the cartilage with the degree of articular cartilage damage in osteoarthritis (OA) patients. Cartilage samples were obtained from twenty patients aged from 46 to 68 years undergoing total knee arthroplasty. In each patient, medial and lateral tibial plateau samples were analysed applying OARSI histopathology grading. Positive correlation was noted between the extent of CILP-2 staining intensity and OARSI grades. Abundant staining for CILP-2 was found in the superficial and middle layers and in the pericellular matrix (PCM) of the deep zone. Transmission electron microscopy studies demonstrated strong damage of chondrocytes, the organelles were often diminished or focally aggregated. As a characteristic finding, PCM was frequently expanded, which may reflect a pathogenic step in OA progression. In conclusion, CILP-2 may potentially be a relevant marker of OA progression as its expression correlated better with cartilage damage than the known marker of articular cartilage damage, DDR2.
Keywords: CILP-2; Chondrocyte; DDR2; Immunohistochemistry; Osteoarthritis; Transmission electron microscopy.
© 2022. The Author(s) under exclusive licence to The Japanese Society for Clinical Molecular Morphology.