Natural joint lubricant may work in arthritis treatment

Researchers at Duke University's Pratt School of Engineering have found new evidence that explains how the body's natural joint lubricant prevents the wear and tear that can lead to osteoarthritis. The team, lead by Stefan Zauscher, an assistant professor of mechanical engineering and materials science at Duke's Pratt School, hopes that these findings may lead to new methods for treating arthritis.

The three constituents of joint fluid, lubricin, hyaluronic acid (HA) and lipids, are thought to play a role in mediating the friction incurred by joint motion. While scientists had speculated that lubricin contributes to the unique frictional properties of the joint, the mechanism by which it prevents wear and tear has been controversial.

A new method using atomic force microscopy (AFM) allowed the researchers to directly measurements of the forces on model joints. AFM is a cutting-edge technique for analyzing forces on the surface of materials on the molecular level. The researchers tested the lubricating effects of mixtures containing varying concentrations of lubricin on the forces between a tiny bead and a glass slide. For the purposes of the study, both the beat and the glasses had their surfaces chemically modified surfaces in order to mimick those found in joints.

Using these realistic models of joints, the team found that lubricin forms a very thin barrier that repels joint surfaces to prevent contact. The researchers further found that lubricin, in combination with HA, produces an even greater protective effect than either of the components alone. The role of lubricin is not to reduce friction, then, but rather to protect sliding surfaces from wear by forming a protective barrier between them.

The findings have important clinical implications for the development of future therapies for osteoarthritis, as well as for patients with a rare genetic disease, in which their joints cannot produce functional lubricin. In the past, osteoarthritis has been especially difficult to treat since the complex chemical and structural properties of joint surfaces were uncertain. Now, however, with this new evidence in hand, the team will next examine the lubricant's role in keeping joints limber in hopes of someday developing a viable treatment for arthritis sufferers.

Article References
Lubricin research points to future therapies for osteoarthritis, site accessed on 4/11/06.