Recombinant lubricin improves anti-adhesive, wear protection, and lubrication of collagen II surface

Camptodactyly-arthropathy-coxa vara-pericarditis syndrome (CACP) is a joint disease caused by a lack of lubricin, resulting in failed lubrication and abnormal deposition at the cartilage surface. Injection of recombinant lubricin (R-LUB) is a promising approach to improve the symptoms of the disease. However, the antifouling and lubrication properties of R-LUB on cartilage surfaces have not yet been studied. Here, the adsorption and lubrication behavior of a type II collagen (COL II) mimicking the cartilage surface upon R-LUB injection was followed by surface plasmon resonance spectroscopy and surface forces apparatus. The results indicated R-LUB can bind well on a COL II surface and COL II/R-LUB complex layer exhibited ultralow nonspecific adsorption of BSA (3.25 ng/cm²) and LYS (0.26 ng/cm²) compared to those of the COL II layer (32.7 ng/cm², 7.26 ng/cm²). Normal force measurements indicated there was always a repulsive force between COL II/R-LUB complex and different surfaces with -COO^-, -NH₃^+, and -CH₃ groups. Likewise, COL II had a high coefficient of friction (∼0.48) with surface damage at 2 µm/s and a wear pressure of 1.56 MPa, while that of COL II/R-LUB complex was down to ∼0.008-0.13 with surface damage at 13 µm/s and a wear pressure of 11.96 MPa, which was 7.7 times higher than for COL II. Hence, R-LUB may act as an anti-adhesive and lubrication layer adsorbed on COL II surfaces to prevent direct contact. Our findings provide fundamental insights into the adsorption and lubrication behavior for understanding biological lubrication, especially the potential supplementation of R-LUB for treating CACP disease.